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Sample records for scanning laser polarimetry

  1. Scanning laser polarimetry in glaucoma.

    Science.gov (United States)

    Dada, Tanuj; Sharma, Reetika; Angmo, Dewang; Sinha, Gautam; Bhartiya, Shibal; Mishra, Sanjay K; Panda, Anita; Sihota, Ramanjit

    2014-11-01

    Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.

  2. Determination of foveal location using scanning laser polarimetry.

    Science.gov (United States)

    VanNasdale, Dean A; Elsner, Ann E; Weber, Anke; Miura, Masahiro; Haggerty, Bryan P

    2009-03-25

    The fovea is the retinal location responsible for our most acute vision. There are several methods used to localize the fovea, but the fovea is not always easily identifiable. Landmarks used to determine the foveal location are variable in normal subjects and localization becomes even more difficult in instances of retinal disease. In normal subjects, the photoreceptor axons that make up the Henle fiber layer are cylindrical and the radial orientation of these fibers is centered on the fovea. The Henle fiber layer exhibits form birefringence, which predictably changes polarized light in scanning laser polarimetry imaging. In this study 3 graders were able to repeatably identify the fovea in 35 normal subjects using near infrared image types with differing polarization content. There was little intra-grader, inter-grader, and inter-image variability in the graded foveal position for 5 of the 6 image types examined, with accuracy sufficient for clinical purposes. This study demonstrates that scanning laser polarimetry imaging can localize the fovea by using structural properties inherent in the central macula.

  3. Retinal nerve fiber layer assessment by scanning laser polarimetry and standardized photography

    NARCIS (Netherlands)

    Niessen, A. G.; van den Berg, T. J.; Langerhorst, C. T.; Greve, E. L.

    1996-01-01

    To determine whether, in a clinical setting, scanning laser polarimetry and retinal nerve fiber layer photography provide equivalent information on the retinal nerve fiber layer. We prospectively studied 60 patients with glaucoma or ocular hypertension and 24 healthy subjects. With scanning laser

  4. Laser polarimetry

    International Nuclear Information System (INIS)

    Goldstein, D.H.

    1989-01-01

    Polarimetry, or transmission ellipsometry, is an important experimental technique for the determination of polarization properties of bulk materials. In this technique, source radiation of known polarization is passed through bulk samples to determine, for example, natural or induced birefringence and dichroism. The laser is a particularly appropriate source for this technique because of its monochromaticity, collimation, and radiant intensity. Lasers of many different wavelengths in different spectral regions are now available. Laser polarimetry can be done in any of these wavelength regions where polarizing elements are available. In this paper, polarimetry is reviewed with respect to applications, sources used, and polarization state generator and analyzer configurations. Scattering ellipsometry is also discussed insofar as the forward scattering measurement is related to polarimetry. The authors then describe an infrared laser polarimeter which we have designed and constructed. This instrument can operate over large wavelength regions with only a change in source. Polarization elements of the polarimeter are in a dual rotating retarder configuration. Computer controlled rotary stages and computer monitored detectors automate the data collection. The Mueller formulation is used to process the polarization information. Issues and recent progress with this instrument are discussed

  5. Scanning laser topography and scanning laser polarimetry: comparing both imaging methods at same distances from the optic nerve head.

    Science.gov (United States)

    Kremmer, Stephan; Keienburg, Marcus; Anastassiou, Gerasimos; Schallenberg, Maurice; Steuhl, Klaus-Peter; Selbach, J Michael

    2012-01-01

    To compare the performance of scanning laser topography (SLT) and scanning laser polarimetry (SLP) on the rim of the optic nerve head and its surrounding area and thereby to evaluate whether these imaging technologies are influenced by other factors beyond the thickness of the retinal nerve fiber layer (RNFL). A total of 154 eyes from 5 different groups were examined: young healthy subjects (YNorm), old healthy subjects (ONorm), patients with normal tension glaucoma (NTG), patients with open-angle glaucoma and early glaucomatous damage (OAGE) and patients with open-angle glaucoma and advanced glaucomatous damage (OAGA). SLT and SLP measurements were taken. Four concentric circles were superimposed on each of the images: the first one measuring at the rim of the optic nerve head (1.0 ONHD), the next measuring at 1.25 optic nerve head diameters (ONHD), at 1.5 ONHD and at 1.75 ONHD. The aligned images were analyzed using GDx/NFA software. Both methods showed peaks of RNFL thickness in the superior and inferior segments of the ONH. The maximum thickness, registered by the SLT device was at the ONH rim where the SLP device tended to measure the lowest values. SLT measurements at the ONH were influenced by other tissues besides the RNFL like blood vessels and glial tissues. SLT and SLP were most strongly correlated at distances of 1.25 and 1.5 ONHD. While both imaging technologies are valuable tools in detecting glaucoma, measurements at the ONH rim should be interpreted critically since both methods might provide misleading results. For the assessment of the retinal nerve fiber layer we would like to recommend for both imaging technologies, SLT and SLP, measurements in 1.25 and 1.5 ONHD distance of the rim of the optic nerve head.

  6. Diagnostic capability of scanning laser polarimetry with and without enhanced corneal compensation and optical coherence tomography.

    Science.gov (United States)

    Benítez-del-Castillo, Javier; Martinez, Antonio; Regi, Teresa

    2011-01-01

    To compare the abilities of the current commercially available versions of scanning laser polarimetry (SLP) and optical coherence tomography (OCT), SLP-variable corneal compensation (VCC), SLP-enhanced corneal compensation (ECC), and high-definition (HD) OCT, in discriminating between healthy eyes and those with early-to-moderate glaucomatous visual field loss. Healthy volunteers and patients with glaucoma who met the eligibility criteria were consecutively enrolled in this prospective, cross-sectional, observational study. Subjects underwent complete eye examination, automated perimetry, SLP-ECC, SLP-VCC, and HD-OCT. Scanning laser polarimetry parameters were recalculated in 90-degree segments (quadrants) in the calculation circle to be compared. Areas under the receiver operating characteristic curve (AUROCs) were calculated for every parameter in order to compare the ability of each imaging modality to differentiate between normal and glaucomatous eyes. Fifty-five normal volunteers (mean age 59.1 years) and 33 patients with glaucoma (mean age 63.8 years) were enrolled. Average visual field mean deviation was -6.69 dB (95% confidence interval -8.07 to -5.31) in the glaucoma group. The largest AUROCs were associated with nerve fiber indicator (0.880 and 0.888) for the SLP-VCC and SLP-ECC, respectively, and with the average thickness in the HD-OCT (0.897). The best performing indices for the SLP-VCC, SLP-ECC, and HD OCT gave similar AUROCs, showing moderate diagnostic accuracy in patients with early to moderate glaucoma. Further studies are needed to evaluate the ability of these technologies to discriminate between normal and glaucomatous eyes.

  7. Optical coherence tomography, scanning laser polarimetry and confocal scanning laser ophthalmoscopy in retinal nerve fiber layer measurements of glaucoma patients.

    Science.gov (United States)

    Fanihagh, Farsad; Kremmer, Stephan; Anastassiou, Gerasimos; Schallenberg, Maurice

    2015-01-01

    To determine the correlations and strength of association between different imaging systems in analyzing the retinal nerve fiber layer (RNFL) of glaucoma patients: optical coherence tomography (OCT), scanning laser polarimetry (SLP) and confocal scanning laser ophthalmoscopy (CSLO). 114 eyes of patients with moderate open angle glaucoma underwent spectral domain OCT (Topcon SD-OCT 2000 and Zeiss Cirrus HD-OCT), SLP (GDx VCC and GDx Pro) and CSLO (Heidelberg Retina Tomograph, HRT 3). Correlation coefficients were calculated between the structural parameters yielded by these examinations. The quantitative relationship between the measured RNFL thickness globally and for the four regions (superior, inferior, nasal, temporal) were evaluated with different regression models for all used imaging systems. The strongest correlation of RNFL measurements was found between devices using the same technology like GDx VCC and GDx Pro as well as Topcon OCT and Cirrus OCT. In glaucoma patients, the strongest associations (R²) were found between RNFL measurements of the two optical coherence tomography devices Topcon OCT and Cirrus OCT (R² = 0.513) and between GDx VCC and GDx Pro (R² = 0.451). The results of the OCTs and GDX Pro also had a strong quantitative relationship (Topcon OCT R² = 0.339 and Cirrus OCT R² = 0.347). GDx VCC and the OCTs showed a mild to moderate association (Topcon OCT R² = 0.207 and Cirrus OCT R² = 0.258). The confocal scanning laser ophthalmoscopy (HRT 3) had the lowest association to all other devices (Topcon OCT R² = 0.254, Cirrus OCT R² = 0.158, GDx Pro R² = 0.086 and GDx VCC R² = 0.1). The measurements of the RNFL in glaucoma patients reveal a high correlation of OCT and GDx devices because OCTs can measure all major retinal layers and SLP can detect nerve fibers allowing a comparison between the results of this devices. However, CSLO by means of HRT topography can only measure height values of the retinal surface but it cannot distinguish

  8. Structure-function relationships using spectral-domain optical coherence tomography: comparison with scanning laser polarimetry.

    Science.gov (United States)

    Aptel, Florent; Sayous, Romain; Fortoul, Vincent; Beccat, Sylvain; Denis, Philippe

    2010-12-01

    To evaluate and compare the regional relationships between visual field sensitivity and retinal nerve fiber layer (RNFL) thickness as measured by spectral-domain optical coherence tomography (OCT) and scanning laser polarimetry. Prospective cross-sectional study. One hundred and twenty eyes of 120 patients (40 with healthy eyes, 40 with suspected glaucoma, and 40 with glaucoma) were tested on Cirrus-OCT, GDx VCC, and standard automated perimetry. Raw data on RNFL thickness were extracted for 256 peripapillary sectors of 1.40625 degrees each for the OCT measurement ellipse and 64 peripapillary sectors of 5.625 degrees each for the GDx VCC measurement ellipse. Correlations between peripapillary RNFL thickness in 6 sectors and visual field sensitivity in the 6 corresponding areas were evaluated using linear and logarithmic regression analysis. Receiver operating curve areas were calculated for each instrument. With spectral-domain OCT, the correlations (r(2)) between RNFL thickness and visual field sensitivity ranged from 0.082 (nasal RNFL and corresponding visual field area, linear regression) to 0.726 (supratemporal RNFL and corresponding visual field area, logarithmic regression). By comparison, with GDx-VCC, the correlations ranged from 0.062 (temporal RNFL and corresponding visual field area, linear regression) to 0.362 (supratemporal RNFL and corresponding visual field area, logarithmic regression). In pairwise comparisons, these structure-function correlations were generally stronger with spectral-domain OCT than with GDx VCC and with logarithmic regression than with linear regression. The largest areas under the receiver operating curve were seen for OCT superior thickness (0.963 ± 0.022; P polarimetry, and was better expressed logarithmically than linearly. Measurements with these 2 instruments should not be considered to be interchangeable. Copyright © 2010 Elsevier Inc. All rights reserved.

  9. Scanning laser polarimetry retinal nerve fiber layer thickness measurements after LASIK.

    Science.gov (United States)

    Zangwill, Linda M; Abunto, Teresa; Bowd, Christopher; Angeles, Raymund; Schanzlin, David J; Weinreb, Robert N

    2005-02-01

    To compare retinal nerve fiber layer (RNFL) thickness measurements before and after LASIK. Cohort study. Twenty participants undergoing LASIK and 14 normal controls. Retinal nerve fiber layer thickness was measured before LASIK and approximately 3 months after surgery in one eye each of 20 patients using a scanning laser polarimeter (GDx Nerve Fiber Analyzer) with fixed corneal compensation (FCC), one with variable corneal compensation (GDx VCC), and optical coherence tomography (OCT). Fourteen normal controls also were tested at baseline and approximately 3 months later. Retinal nerve fiber layer thicknesses measured with the GDx FCC, GDx VCC, and OCT. At baseline, mean (95% confidence interval [CI]) RNFL thicknesses for the GDx FCC, GDx VCC, and OCT were 78.1 microm (72.2-83.9), 54.3 microm (52.7-56.0), and 96.8 microm (93.2-100.5), respectively. In both LASIK and control groups, there were no significant changes between baseline and follow-up examinations in GDx VCC and OCT RNFL thickness measurements globally or in the superior and inferior quadrants (mean change, FCC measurements between baseline and follow-up. In LASIK patients, significant reductions were observed in GDx FCC RNFL measurements. Average absolute values of the mean (95% CI) change in thickness were 12.4 microm (7.7-17.2), 15.3 microm (9.6-20.9), and 12.9 microm (7.6-18.1) for GDx FCC RNFL measurements superiorly, inferiorly, and globally, respectively (all Ps FCC RNFL thickness measurements after LASIK is a measurement artifact and is most likely due to erroneous compensation for corneal birefringence. With scanning laser polarimetry, it is mandatory to compensate individually for change in corneal birefringence after LASIK to ensure accurate RNFL assessment.

  10. Structure-function correlations using scanning laser polarimetry in primary angle-closure glaucoma and primary open-angle glaucoma.

    Science.gov (United States)

    Lee, Pei-Jung; Liu, Catherine Jui-Ling; Wojciechowski, Robert; Bailey-Wilson, Joan E; Cheng, Ching-Yu

    2010-05-01

    To assess the correlations between retinal nerve fiber layer (RNFL) thickness measured with scanning laser polarimetry and visual field (VF) sensitivity in primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). Prospective, comparative, observational cases series. Fifty patients with POAG and 56 patients with PACG were examined using scanning laser polarimetry with variable corneal compensation (GDx VCC; Laser Diagnostic Technologies, Inc.) and Humphrey VF analyzer (Carl Zeiss Meditec, Inc.) between August 2005 and July 2006 at Taipei Veterans General Hospital. Correlations between RNFL thickness and VF sensitivity, expressed as mean sensitivity in both decibel and 1/Lambert scales, were estimated by the Spearman rank correlation coefficient (r(s)) and multivariate median regression models (pseudo R(2)). The correlations were determined globally and for 6 RNFL sectors and their corresponding VF regions. The correlation between RNFL thickness and mean sensitivity (in decibels) was weaker in the PACG group (r(s) = 0.38; P = .004; pseudo R(2) = 0.17) than in the POAG group (r(s) = 0.51; P polarimetry. Compared with eyes with POAG, fewer RNFL sectors have significant structure-function correlations in eyes with PACG. Copyright 2010 Elsevier Inc. All rights reserved.

  11. Retinal degeneration in progressive supranuclear palsy measured by optical coherence tomography and scanning laser polarimetry.

    Science.gov (United States)

    Stemplewitz, Birthe; Kromer, Robert; Vettorazzi, Eik; Hidding, Ute; Frings, Andreas; Buhmann, Carsten

    2017-07-13

    This cross-sectional study compared the retinal morphology between patients with progressive supranuclear palsy (PSP) and healthy controls. (The retinal nerve fiber layer (RNFL) around the optic disc and the retina in the macular area of 22 PSP patients and 151 controls were investigated by spectral domain optical coherence tomography (SD-OCT). Additionally, the RNFL and the nerve fiber index (NFI) were measured by scanning laser polarimetry (SLP). Results of RNFL measurements with SD-OCT and SLP were compared to assess diagnostic discriminatory power. Applying OCT, PSP patients showed a smaller RNFL thickness in the inferior nasal and inferior temporal areas. The macular volume and the thickness of the majority of macular sectors were reduced compared to controls. SLP data showed a thinner RNFL thickness and an increase in the NFI in PSP patients. Sensitivity and specificity to discriminate PSP patients from controls were higher applying SLP than SD-OCT. Retinal changes did not correlate with disease duration or severity in any OCT or SLP measurement. PSP seems to be associated with reduced thickness and volume of the macula and reduction of the RNFL, independent of disease duration or severity. Retinal imaging with SD-OCT and SLP might become an additional tool in PSP diagnosis.

  12. Retinal nerve fiber layer measurements by scanning laser polarimetry with enhanced corneal compensation in healthy subjects.

    Science.gov (United States)

    Rao, Harsha L; Venkatesh, Chirravuri R; Vidyasagar, Kelli; Yadav, Ravi K; Addepalli, Uday K; Jude, Aarthi; Senthil, Sirisha; Garudadri, Chandra S

    2014-12-01

    To evaluate the (i) effects of biological (age and axial length) and instrument-related [typical scan score (TSS) and corneal birefringence] parameters on the retinal nerve fiber layer (RNFL) measurements and (ii) repeatability of RNFL measurements with the enhanced corneal compensation (ECC) protocol of scanning laser polarimetry (SLP) in healthy subjects. In a cross-sectional study, 140 eyes of 73 healthy subjects underwent RNFL imaging with the ECC protocol of SLP. Linear mixed modeling methods were used to evaluate the effects of age, axial length, TSS, and corneal birefringence on RNFL measurements. One randomly selected eye of 48 subjects from the cohort underwent 3 serial scans during the same session to determine the repeatability. Age significantly influenced all RNFL measurements. RNFL measurements decreased by 1 µm for every decade increase in age. TSS affected the overall average RNFL measurement (β=-0.62, P=0.003), whereas residual anterior segment retardance affected the superior quadrant measurement (β=1.14, P=0.01). Axial length and corneal birefringence measurements did not influence RNFL measurements. Repeatability, as assessed by the coefficient of variation, ranged between 1.7% for the overall average RNFL measurement and 11.4% for th nerve fiber indicator. Age significantly affected all RNFL measurements with the ECC protocol of SLP, whereas TSS and residual anterior segment retardance affected the overall average and the superior average RNFL measurements, respectively. Axial length and corneal birefringence measurements did not influence any RNFL measurements. RNFL measurements had good intrasession repeatability. These results are important while evaluating the change in structural measurements over time in glaucoma patients.

  13. Atypical retardation patterns in scanning laser polarimetry are associated with low peripapillary choroidal thickness.

    Science.gov (United States)

    Tornow, Ralf P; Schrems, Wolfgang A; Bendschneider, Delia; Horn, Folkert K; Mayer, Markus; Mardin, Christian Y; Lämmer, Robert

    2011-09-29

    Scanning laser polarimetry (SLP) results can be affected by an atypical retardation pattern (ARP). One reason for an ARP is the birefringence of the sclera. The purpose of this study was to investigate the influence of the peripapillary choroidal thickness (pChTh) on the occurrence of ARP. One hundred ten healthy subjects were investigated with SLP and spectral domain OCT. pChTh was measured in B-scan images at 768 positions using semiautomatic software. Values were averaged to 32 sectors and the total peripapillary mean. Subjects were divided into four groups according to the typical scan score (TSS) provided by the GDxVCC: group 1 TSS, 100; group 2 TSS, 90-99; group 3 TSS, 80-89; group 4 TSS, <80. Mean pChTh (± SD) in 110 healthy subjects was 141 μm (±49 μm). There was a significant correlation between pChTh and TSS (r = 0.608; P < 0.001). In TSS groups 1 to 4, mean pChTh was 168 μm (±38 μm), 148 μm (± 48 μm), 119 μm (±35 μm), and 92 (±42 μm). Mean pChTh of TSS groups 3 and 4 was significantly lower than that of TSS group 1 (P < 0.001). Low values of TSS resulting from the appearance of ARP in SLP are associated with low peripapillary choroidal thickness. Reduced choroidal thickness may result in an increased amount of confounding light getting to the SLP light detectors.

  14. Scanning Laser Polarimetry and Optical Coherence Tomography for Detection of Retinal Nerve Fiber Layer Defects

    Science.gov (United States)

    Oh, Jong-Hyun

    2009-01-01

    Purpose To compare the ability of scanning laser polarimetry with variable corneal compensation (GDx-VCC) and Stratus optical coherence tomography (OCT) to detect photographic retinal nerve fiber layer (RNFL) defects. Methods This retrospective cross-sectional study included 45 eyes of 45 consecutive glaucoma patients with RNFL defects in red-free fundus photographs. The superior and inferior temporal quadrants in each eye were included for data analysis separately. The location and presence of RNFL defects seen in red-free fundus photographs were compared with those seen in GDx-VCC deviation maps and OCT RNFL analysis maps for each quadrant. Results Of the 90 quadrants (45 eyes), 31 (34%) had no apparent RNFL defects, 29 (32%) had focal RNFL defects, and 30 (33%) had diffuse RNFL defects in red-free fundus photographs. The highest agreement between GDx-VCC and red-free photography was 73% when we defined GDx-VCC RNFL defects as a cluster of three or more color-coded squares (p<5%) along the traveling line of the retinal nerve fiber in the GDx-VCC deviation map (kappa value, 0.388; 95% confidence interval (CI), 0.195 to 0.582). The highest agreement between OCT and red-free photography was 85% (kappa value, 0.666; 95% CI, 0.506 to 0.825) when a value of 5% outside the normal limit for the OCT analysis map was used as a cut-off value for OCT RNFL defects. Conclusions According to the kappa values, the agreement between GDx-VCC deviation maps and red-free photography was poor, whereas the agreement between OCT analysis maps and red-free photography was good. PMID:19794943

  15. Combining Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry for Glaucoma Detection.

    Science.gov (United States)

    Mwanza, Jean-Claude; Warren, Joshua L; Hochberg, Jessica T; Budenz, Donald L; Chang, Robert T; Ramulu, Pradeep Y

    2015-01-01

    To determine the ability of frequency doubling technology (FDT) and scanning laser polarimetry with variable corneal compensation (GDx-VCC) to detect glaucoma when used individually and in combination. One hundred ten normal and 114 glaucomatous subjects were tested with FDT C-20-5 screening protocol and the GDx-VCC. The discriminating ability was tested for each device individually and for both devices combined using GDx-NFI, GDx-TSNIT, number of missed points of FDT, and normal or abnormal FDT. Measures of discrimination included sensitivity, specificity, area under the curve (AUC), Akaike's information criterion (AIC), and prediction confidence interval lengths. For detecting glaucoma regardless of severity, the multivariable model resulting from the combination of GDx-TSNIT, number of abnormal points on FDT (NAP-FDT), and the interaction GDx-TSNIT×NAP-FDT (AIC: 88.28, AUC: 0.959, sensitivity: 94.6%, specificity: 89.5%) outperformed the best single-variable model provided by GDx-NFI (AIC: 120.88, AUC: 0.914, sensitivity: 87.8%, specificity: 84.2%). The multivariable model combining GDx-TSNIT, NAP-FDT, and interaction GDx-TSNIT×NAP-FDT consistently provided better discriminating abilities for detecting early, moderate, and severe glaucoma than the best single-variable models. The multivariable model including GDx-TSNIT, NAP-FDT, and the interaction GDx-TSNIT×NAP-FDT provides the best glaucoma prediction compared with all other multivariable and univariable models. Combining the FDT C-20-5 screening protocol and GDx-VCC improves glaucoma detection compared with using GDx or FDT alone.

  16. Comparison of Optical Coherence Tomography and Scanning Laser Polarimetry Measurements in Patients with Multiple Sclerosis

    Science.gov (United States)

    Quelly, Amanda; Cheng, Han; Laron, Michal; Schiffman, Jade S.; Tang, Rosa A.

    2010-01-01

    Purpose To compare optical coherence tomography (OCT) and scanning laser polarimetry (GDx) measurements of the retinal nerve fiber layer (RNFL) in multiple sclerosis (MS) patients with and without optic neuritis (ON). Methods OCT and GDx were performed on 68 MS patients. Qualifying eyes were divided into two groups: 51 eyes with an ON history ≥ 6 months prior (ON eyes), and 65 eyes with no history of ON (non-ON eyes). Several GDx and OCT parameters and criteria were used to define an eye as abnormal, for example, GDx nerve fiber indicator (NFI) above 20 or 30, OCT average RNFL thickness and GDx temporal-superior-nasal-inferior-temporal average (TSNIT) below 5% or 1% of the instruments’ normative database. Agreement between OCT and GDx parameters was reported as percent of observed agreement, along with the AC1 statistic. Linear regression analyses were used to examine the relationship between OCT average RNFL thickness and GDx NFI and TSNIT. Results All OCT and GDx measurements showed significantly more RNFL damage in ON than in non-ON eyes. Agreement between OCT and GDx parameters ranged from 69–90% (AC1 0.37–0.81) in ON eyes, and 52–91% (AC1 = 0.21–0.90) in non-ON eyes. Best agreement was observed between OCT average RNFL thickness (P 30) in ON eyes (90%, AC1 = 0.81), and between OCT average RNFL thickness (P < 0.01) and GDx TSNIT average (P < 0.01) in non-ON eyes (91%, AC1 = 0.90). In ON eyes, the OCT average RNFL thickness showed good linear correlation with NFI (R2 = 0.69, P < 0.0001) and TSNIT (R2 = 0.55, P < 0.0001). Conclusions OCT and GDx show good agreement and can be useful in detecting RNFL loss in MS/ON eyes. PMID:20495500

  17. Evaluation of retinal nerve fiber layer thickness parameters in myopic population using scanning laser polarimetry (GDxVCC).

    Science.gov (United States)

    Dada, Tanuj; Aggarwal, A; Bali, S J; Sharma, A; Shah, B M; Angmo, D; Panda, A

    2013-01-01

    Myopia presents a significant challenge to the ophthalmologist as myopic discs are often large, tilted, with deep cups and have a thinner neuroretinal rim all of which may mimic glaucomatous optic nerve head changes causing an error in diagnosis. To evaluate the retinal fiber layer (RNFL) thickness in low, moderate and high myopia using scanning laser polarimetry with variable corneal compensation (GDxVCC). One hundred eyes of 100 emmetropes, 30 eyes of low myopes (0 to - 4 D spherical equivalent(SE), 45 eyes with moderate myopia (- 4 to - 8D SE), and 30 eyes with high myopia (- 8 to - 15D SE) were subjected to retinal nerve fiber layer assessment using the scanning laser polarimetry (GDxVCC) in all subjects using the standard protocol. Subjects with IOP > 21 mm Hg, optic nerve head or visual field changes suggestive of glaucoma were excluded from the study. The major outcome parameters were temporal-superior-nasal-inferiortemporal (TSNIT) average, the superior and inferior average and the nerve fibre indicator (NFI). The TSNIT average (p = 0.009), superior (p = 0.001) and inferior average (p = 0.008) were significantly lower; the NFI was higher (P less than 0.001) in moderate myopes as compared to that in emmetropes. In high myopia the RNFL showed supranormal values; the TSNIT average, superior and inferior average was significantly higher(p less than 0.001) as compared to that in emmetropes. The RNFL measurements on scanning laser polarimetry are affected by the myopic refractive error. Moderate myopes show a significant thinning of the RNFL. In high myopia due to peripapillary chorioretinal atrophy and contribution of scleral birefringence, the RNFL values are abnormally high. These findings need to be taken into account while assessing and monitoring glaucoma damage in moderate to high myopes on GDxVCC. © NEPjOPH.

  18. Predictive Factors for Visual Field Conversion: Comparison of Scanning Laser Polarimetry and Optical Coherence Tomography.

    Science.gov (United States)

    Diekmann, Theresa; Schrems-Hoesl, Laura M; Mardin, Christian Y; Laemmer, Robert; Horn, Folkert K; Kruse, Friedrich E; Schrems, Wolfgang A

    2018-02-01

    The purpose of this study was to compare the ability of scanning laser polarimetry (SLP) and spectral-domain optical coherence tomography (SD-OCT) to predict future visual field conversion of subjects with ocular hypertension and early glaucoma. All patients were recruited from the Erlangen glaucoma registry and examined using standard automated perimetry, 24-hour intraocular pressure profile, and optic disc photography. Peripapillary retinal nerve fiber layer thickness (RNFL) measurements were obtained by SLP (GDx-VCC) and SD-OCT (Spectralis OCT). Positive and negative predictive values (PPV, NPV) were calculated for morphologic parameters of SLP and SD-OCT. Kaplan-Meier survival curves were plotted and log-rank tests were performed to compare the survival distributions. Contingency tables and Venn-diagrams were calculated to compare the predictive ability. The study included 207 patients-75 with ocular hypertension, 85 with early glaucoma, and 47 controls. Median follow-up was 4.5 years. A total of 29 patients (14.0%) developed visual field conversion during follow-up. SLP temporal-inferior RNFL [0.667; 95% confidence interval (CI), 0.281-0.935] and SD-OCT temporal-inferior RNFL (0.571; 95% CI, 0.317-0.802) achieved the highest PPV; nerve fiber indicator (0.923; 95% CI, 0.876-0.957) and SD-OCT mean (0.898; 95% CI, 0.847-0.937) achieved the highest NPV of all investigated parameters. The Kaplan-Meier curves confirmed significantly higher survival for subjects within normal limits of measurements of both devices (P<0.001). Venn diagrams tested with McNemar test statistics showed no significant difference for PPV (P=0.219) or NPV (P=0.678). Both GDx-VCC and SD-OCT demonstrate comparable results in predicting future visual field conversion if taking typical scans for GDx-VCC. In addition, the likelihood ratios suggest that GDx-VCC's nerve fiber indicator<30 may be the most useful parameter to confirm future nonconversion. (http://www.ClinicalTrials.gov number, NTC

  19. Effect of cataract surgery on retinal nerve fiber layer thickness parameters using scanning laser polarimetry (GDxVCC).

    Science.gov (United States)

    Dada, Tanuj; Behera, Geeta; Agarwal, Anand; Kumar, Sanjeev; Sihota, Ramanjit; Panda, Anita

    2010-01-01

    To study the effect of cataract extraction on the retinal nerve fiber layer (RNFL) thickness, and assessment by scanning laser polarimetry (SLP), with variable corneal compensation (GDx VCC), at the glaucoma service of a tertiary care center in North India. Thirty-two eyes of 32 subjects were enrolled in the study. The subjects underwent RNFL analysis by SLP (GDx VCC) before undergoing phacoemulsification cataract extraction with intraocular lens (IOL) implantation (Acrysof SA 60 AT) four weeks following cataract surgery. The RNFL thickness parameters evaluated both before and after surgery included temporal, superior, nasal, inferior, temporal (TSNIT) average, superior average, inferior average, and nerve fiber index (NFI). The mean age of subjects was 57.6 +/- 11.7 years (18 males, 14 females). Mean TSNIT average thickness (microm) pre- and post-cataract surgery was 49.2 +/- 14.1 and 56.5 +/- 7.6 ( P = 0.001). There was a statistically significant increase in RNFL thickness parameters (TSNIT average, superior average, and inferior average) and decrease in NFI post-cataract surgery as compared to the baseline values. Mean NFI pre- and post-cataract surgery was 41.3 +/- 15.3 and 21.6 +/- 11.8 ( P = 0.001). Measurement of RNFL thickness parameters by scanning laser polarimetry is significantly altered following cataract surgery. Post the cataract surgery, a new baseline needs to be established for assessing the longitudinal follow-up of a glaucoma patient. The presence of cataract may lead to an underestimation of the RNFL thickness, and this should be taken into account when analyzing progression in a glaucoma patient.

  20. Detection of Progressive Retinal Nerve Fiber Layer Loss in Glaucoma Using Scanning Laser Polarimetry with Variable Corneal Compensation

    Science.gov (United States)

    Medeiros, Felipe A.; Alencar, Luciana M.; Zangwill, Linda M.; Bowd, Christopher; Vizzeri, Gianmarco; Sample, Pamela A.; Weinreb, Robert N.

    2010-01-01

    Purpose To evaluate the ability of scanning laser polarimetry with variable corneal compensation to detect progressive retinal nerve fiber layer (RNFL) loss in glaucoma patients and patients suspected of having the disease. Methods This was an observational cohort study that included 335 eyes of 195 patients. Images were obtained annually with the GDx VCC scanning laser polarimeter, along with optic disc stereophotographs and standard automated perimetry (SAP) visual fields. The median follow-up time was 3.94 years. Progression was determined using commercial software for SAP and by masked assessment of optic disc stereophotographs performed by expert graders. Random coefficient models were used to evaluate the relationship between RNFL thickness measurements over time and progression as determined by SAP and/or stereophotographs. Results From the 335 eyes, 34 (10%) showed progression over time by stereophotographs and/or SAP. Average GDx VCC measurements decreased significantly over time for both progressors as well as non-progressors. However, the rate of decline was significantly higher in the progressing group (−0.70 μm/year) compared to the non-progressing group (−0.14 μm/year; P = 0.001). Black race and male sex were significantly associated with higher rates of RNFL loss during follow-up. Conclusions The GDx VCC scanning laser polarimeter was able to identify longitudinal RNFL loss in eyes that showed progression in optic disc stereophotographs and/or visual fields. These findings suggest that this technology could be useful to detect and monitor progressive disease in patients with established diagnosis of glaucoma or suspected of having the disease. PMID:19029038

  1. Comparative study of the retinal nerve fibre layer thickness performed with optical coherence tomography and GDx scanning laser polarimetry in patients with primary open-angle glaucoma.

    Science.gov (United States)

    Wasyluk, Jaromir T; Jankowska-Lech, Irmina; Terelak-Borys, Barbara; Grabska-Liberek, Iwona

    2012-03-01

    We compared the parameters of retinal nerve fibre layer in patients with advanced glaucoma with the use of different OCT (Optical Coherence Tomograph) devices in relation to analogical measurements performed with GDx VCC (Nerve Fiber Analyzer with Variable Corneal Compensation) scanning laser polarimetry. Study subjects had advanced primary open-angle glaucoma, previously treated conservatively, diagnosed and confirmed by additional examinations (visual field, ophthalmoscopy of optic nerve, gonioscopy), A total of 10 patients were enrolled (9 women and 1 man), aged 18-70 years of age. Nineteen eyes with advanced glaucomatous neuropathy were examined. 1) Performing a threshold perimetry Octopus, G2 strategy and ophthalmoscopy of optic nerve to confirm the presence of advanced primary open-angle glaucoma; 2) performing a GDx VCC scanning laser polarimetry of retinal nerve fibre layer; 3) measuring the retinal nerve fibre layer thickness with 3 different optical coherence tomographs. The parameters of the retinal nerve fibre layer thickness are highly correlated between the GDx and OCT Stratus and 3D OCT-1000 devices in mean retinal nerve fibre layer thickness, retinal nerve fibre layer thickness in the upper sector, and correlation of NFI (GDx) with mean retinal nerve fibre layer thickness in OCT examinations. Absolute values of the retinal nerve fibre layer thickness (measured in µm) differ significantly between GDx and all OCT devices. Examination with OCT devices is a sensitive diagnostic method of glaucoma, with good correlation with the results of GDx scanning laser polarimetry of the patients.

  2. Analysis of the Origin of Atypical Scanning Laser Polarimetry Patterns by Polarization-Sensitive Optical Coherence Tomography

    Science.gov (United States)

    Götzinger, Erich; Pircher, Michael; Baumann, Bernhard; Hirn, Cornelia; Vass, Clemens; Hitzenberger, Christoph K.

    2010-01-01

    Purpose To analyze the physical origin of atypical scanning laser polarimetry (SLP) patterns. To compare polarization-sensitive optical coherence tomography (PS-OCT) scans to SLP images. To present a method to obtain pseudo-SLP images by PS-OCT that are free of atypical artifacts. Methods Forty-one eyes of healthy subjects, subjects with suspected glaucoma, and patients with glaucoma were imaged by SLP (GDx VCC) and a prototype spectral domain PS-OCT system. The PS-OCT system acquires three-dimensional (3D) datasets of intensity, retardation, and optic axis orientation simultaneously within 3 seconds. B-scans of intensity and retardation and en face maps of retinal nerve fiber layer (RNFL) retardation were derived from the 3D PS-OCT datasets. Results were compared with those obtained by SLP. Results Twenty-two eyes showed atypical retardation patterns, and 19 eyes showed normal patterns. From the 22 atypical eyes, 15 showed atypical patterns in both imaging modalities, five were atypical only in SLP images, and two were atypical only in PS-OCT images. In most (15 of 22) atypical cases, an increased penetration of the probing beam into the birefringent sclera was identified as the source of atypical patterns. In such cases, the artifacts could be eliminated in PS-OCT images by depth segmentation and exclusion of scleral signals. Conclusions PS-OCT provides deeper insight into the contribution of different fundus layers to SLP images. Increased light penetration into the sclera can distort SLP retardation patterns of the RNFL. PMID:19036999

  3. Evaluation of baseline structural factors for predicting glaucomatous visual-field progression using optical coherence tomography, scanning laser polarimetry and confocal scanning laser ophthalmoscopy.

    Science.gov (United States)

    Sehi, M; Bhardwaj, N; Chung, Y S; Greenfield, D S

    2012-12-01

    The objective of this study is to assess whether baseline optic nerve head (ONH) topography and retinal nerve fiber layer thickness (RNFLT) are predictive of glaucomatous visual-field progression in glaucoma suspect (GS) and glaucomatous eyes, and to calculate the level of risk associated with each of these parameters. Participants with ≥28 months of follow-up were recruited from the longitudinal Advanced Imaging for Glaucoma Study. All eyes underwent standard automated perimetry (SAP), confocal scanning laser ophthalmoscopy (CSLO), time-domain optical coherence tomography (TDOCT), and scanning laser polarimetry using enhanced corneal compensation (SLPECC) every 6 months. Visual-field progression was assessed using pointwise linear-regression analysis of SAP sensitivity values (progressor) and defined as significant sensitivity loss of >1 dB/year at ≥2 adjacent test locations in the same hemifield at P<0.01. Cox proportional hazard ratios (HR) were calculated to determine the predictive ability of baseline ONH and RNFL parameters for SAP progression using univariate and multivariate models. Seventy-three eyes of 73 patients (43 GS and 30 glaucoma, mean age 63.2±9.5 years) were enrolled (mean follow-up 51.5±11.3 months). Four of 43 GS (9.3%) and 6 of 30 (20%) glaucomatous eyes demonstrated progression. Mean time to progression was 50.8±11.4 months. Using multivariate models, abnormal CSLO temporal-inferior Moorfields classification (HR=3.76, 95% confidence interval (CI): 1.02-6.80, P=0.04), SLPECC inferior RNFLT (per -1 μm, HR=1.38, 95% CI: 1.02-2.2, P=0.02), and TDOCT inferior RNFLT (per -1 μm, HR=1.11, 95% CI: 1.04-1.2, P=0.001) had significant HRs for SAP progression. Abnormal baseline ONH topography and reduced inferior RNFL are predictive of SAP progression in GS and glaucomatous eyes.

  4. Atypical birefringence pattern and the diagnostic ability of scanning laser polarimetry with enhanced corneal compensation in glaucoma.

    Science.gov (United States)

    Rao, Harsha L; Yadav, Ravi K; Begum, Viquar U; Addepalli, Uday K; Senthil, Sirisha; Choudhari, Nikhil S; Garudadri, Chandra S

    2015-03-01

    To evaluate the effect of typical scan score (TSS), when within the acceptable limits, on the diagnostic performance of retinal nerve fibre layer (RNFL) parameters with the enhanced corneal compensation (ECC) protocol of scanning laser polarimetry (SLP) in glaucoma. In a cross-sectional study, 203 eyes of 160 glaucoma patients and 140 eyes of 104 control subjects underwent RNFL imaging with the ECC protocol of SLP. TSS was used to quantify atypical birefringence pattern (ABP) images. Influence of TSS on the diagnostic ability of SLP parameters was evaluated by receiver operating characteristic (ROC) regression models after adjusting for the effect of disease severity [based on mean deviation (MD)] on standard automated perimetry). Diagnostic abilities of all RNFL parameters of SLP increased when the TSS values were higher. This effect was statistically significant for TSNIT (coefficient: 0.08, p<0.001) and inferior average parameters (coefficient: 0.06, p=0.002) but not for nerve fibre indicator (NFI, coefficient: 0.03, p=0.21). In early glaucoma (MD of -5 dB), predicted area under ROC curve (AUC) for TSNIT average parameter improved from 0.642 at a TSS of 90 to 0.845 at a TSS of 100. In advanced glaucoma (MD of -15 dB), AUC for TSNIT average improved from 0.832 at a TSS of 90 to 0.947 at 100. Diagnostic performances of TSNIT and inferior average RNFL parameters with ECC protocol of SLP were significantly influenced by TSS even when the TSS values were within the acceptable limits. Diagnostic ability of NFI was unaffected by TSS values. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  5. Scanning laser polarimetry and spectral domain optical coherence tomography for the detection of retinal changes in Parkinson's disease.

    Science.gov (United States)

    Stemplewitz, Birthe; Keserü, Matthias; Bittersohl, Diana; Buhmann, Carsten; Skevas, Christos; Richard, Gisbert; Hassenstein, Andrea

    2015-12-01

    Whether retinal degeneration is part of the degenerative processes in patients with Parkinson's disease (PD) is still unclear. This cross-sectional study was undertaken to compare the retinal morphology of patients with PD and healthy controls using spectral domain optical coherence tomography (SD-OCT) and scanning laser polarimetry (SLP). Both eyes of patients with PD (n = 108) and healthy controls (n = 165) were examined using SD-OCT and SLP on the same day. Data on the thickness of the retinal nerve fibre layer (RNFL) of all quadrants and the macular area were acquired by OCT (Cirrus, Zeiss). The SLP device (Glaucoma diagnostics (GDx), Zeiss) measured the RNFL and calculated the nerve fibre index (NFI). All patients and probands were checked for concomitant ocular disorders by an ophthalmologist. Visual acuity, intraocular pressure (IOP), objective refraction and the anterior and posterior segment were assessed. Patients with PD showed a reduced macular volume and a reduced central subfield thickness in OCT examinations. The RNFL in the different quadrants did not differ significantly from that of controls. SLP data showed a reduced average RNFL thickness, a decreased thickness of the inferior quadrant and an increase of the NFI in patients with PD. PD may be associated with reduced thickness and volume of the macula and a reduced thickness of the RNFL in the inferior quadrant of the retina. Investigations using SD-OCT and SLP revealed distinct but significant differences between patients with PD and healthy controls. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  6. Glaucoma progression detection by retinal nerve fiber layer measurement using scanning laser polarimetry: event and trend analysis.

    Science.gov (United States)

    Moon, Byung Gil; Sung, Kyung Rim; Cho, Jung Woo; Kang, Sung Yong; Yun, Sung-Cheol; Na, Jung Hwa; Lee, Youngrok; Kook, Michael S

    2012-06-01

    To evaluate the use of scanning laser polarimetry (SLP, GDx VCC) to measure the retinal nerve fiber layer (RNFL) thickness in order to evaluate the progression of glaucoma. Test-retest measurement variability was determined in 47 glaucomatous eyes. One eye each from 152 glaucomatous patients with at least 4 years of follow-up was enrolled. Visual field (VF) loss progression was determined by both event analysis (EA, Humphrey guided progression analysis) and trend analysis (TA, linear regression analysis of the visual field index). SLP progression was defined as a reduction of RNFL exceeding the predetermined repeatability coefficient in three consecutive exams, as compared to the baseline measure (EA). The slope of RNFL thickness change over time was determined by linear regression analysis (TA). Twenty-two eyes (14.5%) progressed according to the VF EA, 16 (10.5%) by VF TA, 37 (24.3%) by SLP EA and 19 (12.5%) by SLP TA. Agreement between VF and SLP progression was poor in both EA and TA (VF EA vs. SLP EA, k = 0.110; VF TA vs. SLP TA, k = 0.129). The mean (±standard deviation) progression rate of RNFL thickness as measured by SLP TA did not significantly differ between VF EA progressors and non-progressors (-0.224 ± 0.148 µm/yr vs. -0.218 ± 0.151 µm/yr, p = 0.874). SLP TA and EA showed similar levels of sensitivity when VF progression was considered as the reference standard. RNFL thickness as measurement by SLP was shown to be capable of detecting glaucoma progression. Both EA and TA of SLP showed poor agreement with VF outcomes in detecting glaucoma progression.

  7. Scanning laser polarimetry, but not optical coherence tomography predicts permanent visual field loss in acute nonarteritic anterior ischemic optic neuropathy.

    Science.gov (United States)

    Kupersmith, Mark J; Anderson, Susan; Durbin, Mary; Kardon, Randy

    2013-08-15

    Scanning laser polarimetry (SLP) reveals abnormal retardance of birefringence in locations of the edematous peripapillary retinal nerve fiber layer (RNFL), which appear thickened by optical coherence tomography (OCT), in nonarteritic anterior ischemic optic neuropathy (NAION). We hypothesize initial sector SLP RNFL abnormalities will correlate with long-term regional visual field loss due to ischemic injury. We prospectively performed automated perimetry, SLP, and high definition OCT (HD-OCT) of the RNFL in 25 eyes with acute NAION. We grouped visual field threshold and RNFL values into Garway-Heath inferior/superior disc sectors and corresponding superior/inferior field regions. We compared sector SLP RNFL thickness with corresponding visual field values at presentation and at >3 months. At presentation, 12 eyes had superior sector SLP reduction, 11 of which had inferior field loss. Six eyes, all with superior field loss, had inferior sector SLP reduction. No eyes had reduced OCT-derived RNFL acutely. Eyes with abnormal field regions had corresponding SLP sectors thinner (P = 0.003) than for sectors with normal field regions. During the acute phase, the SLP-derived sector correlated with presentation (r = 0.59, P = 0.02) and with >3-month after presentation (r = 0.44, P = 0.02) corresponding superior and inferior field thresholds. Abnormal RNFL birefringence occurs in sectors corresponding to regional visual field loss during acute NAION when OCT-derived RNFL shows thickening. Since the visual field deficits show no significant recovery, SLP can be an early marker for axonal injury, which may be used to assess recovery potential at RNFL locations with respect to new treatments for acute NAION.

  8. Structure-Function Correlations using Scanning Laser Polarimetry in Primary Angle-Closure Glaucoma and Primary Open Angle Glaucoma

    Science.gov (United States)

    Lee, Pei-Jung; Liu, Catherine Jui-Ling.; Wojciechowski, Robert; Bailey-Wilson, Joan E.; Cheng, Ching-Yu

    2010-01-01

    Purpose To assess the correlations between retinal nerve fiber layer (RNFL) thickness measured with scanning laser polarimetry (SLP) and visual field (VF) sensitivity in primary open angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). Design Prospective, comparative, observational cases series Methods Fifty patients with POAG and 56 with PACG were examined using SLP with variable corneal compensation (GDx VCC) and Humphrey VF analyzer between August 2005 and July 2006 at Taipei Veterans General Hospital. Correlations between RNFL thickness and VF sensitivity, expressed as mean sensitivity (MS) in both decibel (dB) and 1/Lambert (L) scales, were estimated by Spearman's rank correlation coefficient (rs) and multivariate median regression models (pseudo R2). The correlations were determined globally and for six RNFL sectors and their corresponding VF regions. Results The correlation between RNFL thickness and MS (in dB) was weaker in the PACG group (rs = 0.38, P = 0.004, pseudo R2 = 0.17) than in the POAG group (rs = 0.51, P <0.001, pseudo R2 = 0.31), but the difference in the magnitude of correlation was not significant (P = 0.42).With Bonferroni correction, the structure-function correlation was significant in the superotemporal (rs = 0.62), superonasal (rs = 0.56), inferonasal (rs = 0.53), and inferotemporal (rs = 0.50) sectors in the POAG group (all P <0.001), while it was significant only in the superotemporal (rs = 0.53) and inferotemporal (rs = 0.48) sectors in the PACG group (both P <0.001). The results were similar when MS was expressed as 1/L scale. Conclusions Both POAG and PACG eyes had moderate structure-function correlations using SLP. Compared to eyes with POAG, fewer RNFL sectors have significant structure-function correlations in eyes with PACG. PMID:20202618

  9. Relevance Vector Machine and Support Vector Machine Classifier Analysis of Scanning Laser Polarimetry Retinal Nerve Fiber Layer Measurements

    Science.gov (United States)

    Bowd, Christopher; Medeiros, Felipe A.; Zhang, Zuohua; Zangwill, Linda M.; Hao, Jiucang; Lee, Te-Won; Sejnowski, Terrence J.; Weinreb, Robert N.; Goldbaum, Michael H.

    2010-01-01

    Purpose To classify healthy and glaucomatous eyes using relevance vector machine (RVM) and support vector machine (SVM) learning classifiers trained on retinal nerve fiber layer (RNFL) thickness measurements obtained by scanning laser polarimetry (SLP). Methods Seventy-two eyes of 72 healthy control subjects (average age = 64.3 ± 8.8 years, visual field mean deviation =−0.71 ± 1.2 dB) and 92 eyes of 92 patients with glaucoma (average age = 66.9 ± 8.9 years, visual field mean deviation =−5.32 ± 4.0 dB) were imaged with SLP with variable corneal compensation (GDx VCC; Laser Diagnostic Technologies, San Diego, CA). RVM and SVM learning classifiers were trained and tested on SLP-determined RNFL thickness measurements from 14 standard parameters and 64 sectors (approximately 5.6° each) obtained in the circumpapillary area under the instrument-defined measurement ellipse (total 78 parameters). Tenfold cross-validation was used to train and test RVM and SVM classifiers on unique subsets of the full 164-eye data set and areas under the receiver operating characteristic (AUROC) curve for the classification of eyes in the test set were generated. AUROC curve results from RVM and SVM were compared to those for 14 SLP software-generated global and regional RNFL thickness parameters. Also reported was the AUROC curve for the GDx VCC software-generated nerve fiber indicator (NFI). Results The AUROC curves for RVM and SVM were 0.90 and 0.91, respectively, and increased to 0.93 and 0.94 when the training sets were optimized with sequential forward and backward selection (resulting in reduced dimensional data sets). AUROC curves for optimized RVM and SVM were significantly larger than those for all individual SLP parameters. The AUROC curve for the NFI was 0.87. Conclusions Results from RVM and SVM trained on SLP RNFL thickness measurements are similar and provide accurate classification of glaucomatous and healthy eyes. RVM may be preferable to SVM, because it provides a

  10. Retinal nerve fiber layer analysis with scanning laser polarimetry and RTVue-OCT in patients of retinitis pigmentosa.

    Science.gov (United States)

    Xue, Kang; Wang, Min; Chen, Junyi; Huang, Xin; Xu, Gezhi

    2013-01-01

    To measure the thickness of the retinal nerve fiber layer (RNFL) of patients with retinitis pigmentosa (RP) and that of normal controls by scanning laser polarimetry with enhanced corneal compensation (GDxECC) and RTVue-optical coherence tomography (OCT). Fifty-two eyes of 26 patients were included. All patients underwent complete ophthalmological examinations and testing with GDxECC. Twenty-eight of 52 eyes of RP patients underwent RTVue-OCT measurements. A group of 50 eyes of 25 normal subjects (controls) was also included. GDxECC measured RNFL thickness in the peripapillary area in all subjects as well as temporal-superior-nasal-inferior-temporal (TSNIT) parameters, including TSNIT means, superior and inferior region means, TSNIT standard deviation (SD), inter-eye symmetry and nerve fiber indicator (NFI). RTVue-OCT measured the mean, superior, inferior, temporal and nasal quadrant RNFL thickness. In RP patients and controls, TSNIT means by GDxECC were, respectively, 65.00 ± 7.35 and 55.32 ± 5.20. Mean superior quadrant thicknesses were 80.56 ± 10.93 and 69.54 ± 7.45. Mean inferior thicknesses were 80.58 ± 9.34 and 69.12 ± 7.78. SDs were 27.92 ± 5.21 and 28.23 ± 4.01. Inter-eye symmetries were 0.82 ± 0.17 and 0.87 ± 0.09. NFIs were 9.74 ± 8.73 and 16.81 ± 8.13. The differences between mean TSNIT, mean superior and mean inferior quadrant thicknesses and NFIs were statistically significant (p < 0.001). In RTVue-OCT measurements, the differences between mean, superior, inferior and temporal quadrant RNFL thicknesses were statistically significant (p = 0.0322, 0.0213, 0.0387, 0.0005). The RNFL measured by GDxECC was significantly thicker in RP patients than in controls. RNFL thickness measured by RTVue-OCT was significantly greater in RP patients than in controls in the superior, inferior and temporal regions. This contribution provides information on RNFL thickness and discusses the mechanism underlying this phenomenon. Copyright © 2012 S. Karger AG

  11. Discriminação entre olhos normais e glaucomatosos mediante polarimetria de varredura a laser Discrimination between normal and glaucomatous eyes by scanning laser polarimetry

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    Leopoldo Magacho

    2004-04-01

    Full Text Available OBJETIVOS: Avaliar a capacidade da polarimetria de varredura a laser de discriminar entre olhos normais e glaucomatosos. MÉTODOS: Cento e doze pacientes com glaucoma primário de ângulo aberto e 88 indivíduos normais foram incluídos no estudo. Todos os indivíduos foram submetidos a exame oftalmológico completo, perimetria computadorizada (Humphrey 24-2, full threshold, avaliando-se Mean Deviation (MD e Correct Pattern Standard Deviation (CPSD e exame com GDx. Curvas ROC foram criadas e novos pontos de corte para cada parâmetro individual do GDx estabelecidos para estabelecer uma melhor relação sensibilidade/especificidade (Se/Es no diagnóstico do glaucoma. A seguir, uma função discriminante com 2 parâmetros do GDx (ellipse modulation e the number e idade por meio da análise logística multivariada foi criada com o mesmo propósito. RESULTADOS: Os parâmetros individuais do GDx com melhor relação Se/Es foram: the number (Se: 79,5%, Es: 81,8%, área abaixo da curva ROC: 0,870, maximum modullation (Se: 83,0%, Es: 76,1%, área abaixo da curva ROC: 0,842 e ellipse modulation (Se: 65,2%, Es: 88,6%, área abaixo da curva ROC: 0,831. A função discriminante criada obteve resultados superiores a qualquer parâmetro do GDx isolado (Se: 85,7%, Es: 90,9%, a área abaixo da curva ROC: 0,920. CONCLUSÃO: A combinação de dois ou mais fatores em uma função logística multivariada aumenta a capacidade da polarimetria de varredura a laser de discriminar entre olhos normais e glaucomatosos.PURPOSE: To test the ability of the scanning laser polarimetry to discriminate between normal and glaucomatous eyes. METHODS: One-hundred and twelve patients with primary open-angle glaucoma and 88 normal individuals were enrolled in the study. All individuals underwent a complete ophthalmic evaluation, a 24-2 full threshold Humphrey visual field and a GDx examination. Cutoff points were selected, ROC curves were created, and the sensitivity (Se and

  12. Scanning laser polarimetry in glaucomatous and nonglaucomatous Brazilian subjects Polarimetria de varredura a laser em grupos de brasileiros glaucomatosos e não glaucomatosos

    Directory of Open Access Journals (Sweden)

    Christiane Rolim de Moura

    2003-12-01

    Full Text Available PURPOSE: To compare the results of scanning laser polarimetry of the retinal nerve fiber layer obtained by using the GDx Scanning Laser System® in primary open angle glaucoma (POAG and nonglaucomatous Brazilian subjects over 40 years, also analyzing the differences between the data obtained from right and left eyes. METHODS: Forty-six POAG patients and 44 normal subjects were enrolled in this study. Retardation data were assessed by the GDx Scanning Laser System®. The medians of the parameters printed in the result were compared in these two groups, separately in the right and left eyes, using Mann-Whitney's test. Also the frequencies of outside normal parameters and quadrants of deviation from normal graph were compared in these two groups, using chi-square or Fisher's exact test. RESULTS: All parameters obtained by GDx differed in a statistically significant way between the two groups, except symmetry for left eyes. The frequency of inferior quadrant with pOBJETIVOS: Comparar os resultados da polarimetria de varredura a laser da camada de fibras nervosas obtidas por meio do GDx Scanning Laser System® em brasileiros portadores de glaucoma primário de ângulo aberto e indivíduos não glaucomatosos acima de 40 anos, analisando também as diferenças obtidas entre olhos direitos e esquerdos. MÉTODOS: Foram incluídos neste estudo 46 pacientes portadores de glaucoma primário de ângulo aberto e 44 pacientes normais. Os dados de retardo polarimétrico foram obtidos por meio do GDx Scanning Laser System®. As medianas dos parâmetros impressos no resultado foram comparadas nesses dois grupos, separadamente para olhos direitos e esquerdos, usando o teste de Mann-Whitney. A freqüência de parâmetros impressa como fora da normalidade e quadrantes estatisticamente alterados do gráfico "deviation from normal" foram comparados nesses dois grupos usando chi-quadrado e o teste exato de Fischer. RESULTADOS: Todos os parâmetros obtidos pelo GDx

  13. Repeatability and Reproducibility of Retinal Nerve Fiber Layer Parameters Measured by Scanning Laser Polarimetry with Enhanced Corneal Compensation in Normal and Glaucomatous Eyes.

    Science.gov (United States)

    Ara, Mirian; Ferreras, Antonio; Pajarin, Ana B; Calvo, Pilar; Figus, Michele; Frezzotti, Paolo

    2015-01-01

    To assess the intrasession repeatability and intersession reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness parameters measured by scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) in healthy and glaucomatous eyes. One randomly selected eye of 82 healthy individuals and 60 glaucoma subjects was evaluated. Three scans were acquired during the first visit to evaluate intravisit repeatability. A different operator obtained two additional scans within 2 months after the first session to determine intervisit reproducibility. The intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) were calculated for all SLP parameters in both groups. ICCs ranged from 0.920 to 0.982 for intravisit measurements and from 0.910 to 0.978 for intervisit measurements. The temporal-superior-nasal-inferior-temporal (TSNIT) average was the highest (0.967 and 0.946) in normal eyes, while nerve fiber indicator (NFI; 0.982) and inferior average (0.978) yielded the best ICC in glaucomatous eyes for intravisit and intervisit measurements, respectively. All COVs were under 10% in both groups, except NFI. TSNIT average had the lowest COV (2.43%) in either type of measurement. Intervisit TRT ranged from 6.48 to 12.84. The reproducibility of peripapillary RNFL measurements obtained with SLP-ECC was excellent, indicating that SLP-ECC is sufficiently accurate for monitoring glaucoma progression.

  14. Influence of atypical retardation pattern on the peripapillary retinal nerve fibre distribution assessed by scanning laser polarimetry and optical coherence tomography.

    Science.gov (United States)

    Schrems, W A; Laemmer, R; Hoesl, L M; Horn, F K; Mardin, C Y; Kruse, F E; Tornow, R P

    2011-10-01

    To investigate the influence of atypical retardation pattern (ARP) on the distribution of peripapillary retinal nerve fibre layer (RNFL) thickness measured with scanning laser polarimetry in healthy individuals and to compare these results with RNFL thickness from spectral domain optical coherence tomography (OCT) in the same subjects. 120 healthy subjects were investigated in this study. All volunteers received detailed ophthalmological examination, GDx variable corneal compensation (VCC) and Spectralis-OCT. The subjects were divided into four subgroups according to their typical scan score (TSS): very typical with TSS=100, typical with 99 ≥ TSS ≥ 91, less typical with 90 ≥ TSS ≥ 81 and atypical with TSS ≤ 80. Deviations from very typical normal values were calculated for 32 sectors for each group. There was a systematic variation of the RNFL thickness deviation around the optic nerve head in the atypical group for the GDxVCC results. The highest percentage deviation of about 96% appeared temporal with decreasing deviation towards the superior and inferior sectors, and nasal sectors exhibited a deviation of 30%. Percentage deviations from very typical RNFL values decreased with increasing TSS. No systematic variation could be found if the RNFL thickness deviation between different TSS-groups was compared with the OCT results. The ARP has a major impact on the peripapillary RNFL distribution assessed by GDx VCC; thus, the TSS should be included in the standard printout.

  15. Laser Imaging Polarimetry of Nacre.

    Science.gov (United States)

    Jones, Joshua A; Metzler, Rebecca A; D'Addario, Anthony J; Burgess, Carrie; Regan, Brian; Spano, Samantha; Cvarch, Ben A; Galvez, Enrique J

    2018-03-25

    Nacre is a complex biomaterial made of aragonite-tablet bricks and organic mortar that is considerably resilient against breakage. Nacre has been studied with a wide range of laboratory techniques, leading to understanding key fundamentals, and informing the creation of bio-inspired materials. In this article we present an optical polarimetric technique to investigate nacre, taking advantage of the translucence and birefringence of its micro-components. We focus our study on three classes of mollusks that have nacreous shells: bivalve (Pinctada fucata), gastropod (Haliotis asisina and Haliotis rufescens) and cephalopod (Nautilus pompilius). We sent polarized light from a laser through thin samples of nacre and did imaging polarimetry of the transmitted light. We observed clear distinctions between the structures of bivalve and gastropod, due to the spatial variation of their birefringence. The patterns for cephalopod were more similar to bivalve than gastropod. Bleaching of the samples disrupted the transmitted light. Subsequent refilling of the bivalve and gastropod nacre samples with oil produced optical patterns similar to those of unbleached samples. In cephalopod samples we found that bleaching produced irreversible changes in the optical pattern. This article is protected by copyright. All rights reserved.

  16. The retinal nerve fibre layer thickness in glaucomatous hydrophthalmic eyes assessed by scanning laser polarimetry with variable corneal compensation in comparison with age-matched healthy children.

    Science.gov (United States)

    Hložánek, Martin; Ošmera, Jakub; Ležatková, Pavlína; Sedláčková, Petra; Filouš, Aleš

    2012-12-01

    To compare the thickness of the retinal nerve fibre layer (RNFL) in hydrophthalmic glaucomatous eyes in children with age-matched healthy controls using scanning laser polarimetry with variable corneal compensation (GDxVCC). Twenty hydrophthalmic eyes of 20 patients with the mean age of 10.64 ± 3.02 years being treated for congenital or infantile glaucoma were included in the analysis. Evaluation of RNFL thickness measured by GDxVCC in standard Temporal-Superior-Nasal-Inferior-Temporal (TSNIT) parameters was performed. The results were compared to TSNIT values of an age-matched control group of 120 healthy children published recently as referential values. The correlation between horizontal corneal diameter and RNFL thickness in hydrophthalmic eyes was also investigated. The mean ± SD values in TSNIT Average, Superior Average, Inferior Average and TSNIT SD in hydrophthalmic eyes were 52.3 ± 11.4, 59.7 ± 17.1, 62.0 ± 15.6 and 20.0 ± 7.8 μm, respectively. All these values were significantly lower compared to referential TSNIT parameters of age-matched healthy eyes (p = 0.021, p = 0.001, p = 0.003 and p = 0.018, respectively). A substantial number of hydrophthalmic eyes laid below the level of 5% probability of normality in respective TSNIT parameters: 30% of the eyes in TSNIT average, 50% of the eyes in superior average, 30% of the eyes in inferior average and 45% of the eyes in TSNIT SD. No significant correlation between enlarged corneal diameter and RNFL thickness was found. The mean values of all standard TSNIT parameters assessed using GDxVCC in hydrophthalmic glaucomatous eyes in children were significantly lower in comparison with referential values of healthy age-matched children. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

  17. Measurement of retinal nerve fiber layer thickness in eyes with optic disc swelling by using scanning laser polarimetry and optical coherence tomography.

    Science.gov (United States)

    Hata, Masayuki; Miyamoto, Kazuaki; Oishi, Akio; Kimura, Yugo; Nakagawa, Satoko; Horii, Takahiro; Yoshimura, Nagahisa

    2014-01-01

    The retinal nerve fiber layer thickness (RNFLT) in patients with optic disc swelling of different etiologies was compared using scanning laser polarimetry (SLP) and spectral-domain optical coherence tomography (OCT). Forty-seven patients with optic disc swelling participated in the cross-sectional study. Both GDx SLP (enhanced corneal compensation) and Spectralis spectral-domain OCT measurements of RNFLT were made in 19 eyes with papilledema (PE), ten eyes with optic neuritis (ON), and 18 eyes with nonarteritic anterior ischemic optic neuropathy (NAION) at the neuro-ophthalmology clinic at Kyoto University Hospital. Differences in SLP (SLP-RNFLT) and OCT (OCT-RNFLT) measurements among different etiologies were investigated. No statistical differences in average OCT-RNFLT among PE, ON, and NAION patients were noted. Average SLP-RNFLT in NAION patients was smaller than in PE (P<0.01) or ON (P=0.02) patients. When RNFLT in each retinal quadrant was compared, no difference among etiologies was noted on OCT, but on SLP, the superior quadrant was thinner in NAION than in PE (P<0.001) or ON (P=0.001) patients. Compared with age-adjusted normative data of SLP-RNFLT, average SLP-RNFLT in PE (P<0.01) and ON (P<0.01) patients was greater. Superior SLP-RNFLT in NAION patients was smaller (P=0.026). The ratio of average SLP-RNFLT to average OCT-RNFLT was smaller in NAION than in PE (P=0.001) patients. In the setting of RNFL thickening, despite increased light retardance in PE and ON eyes, SLP revealed that NAION eyes have less retardance, possibly associated with ischemic axonal loss.

  18. Retinal nerve fiber layer in primary open-angle glaucoma with high myopia determined by optical coherence tomography and scanning laser polarimetry.

    Science.gov (United States)

    Wang, Xiao-en; Wang, Xiao-yu; Gu, Yang-shun; Huang, Zhu

    2013-01-01

    Fundus changes associated with high myopia (HM) may mask those associated with primary open-angle glaucoma (POAG). This study aim to determine the characteristics of RNFL thickness changes in patients with both POAG and HM and compare these to changes in patients with only HM. The diagnostic capabilities of both OCT and GDxVCC in this subset of patients are also evaluated. Twenty-two eyes with POAG and HM (spherical equivalent (SE) between -6.0 and -12.0 D) were evaluated, and 22 eyes with HM were used for comparison. Characteristic retinal nerve fiber layer (RNFL) thickness profiles in patients with POAG and HM were examined using optical coherence tomography (OCT) and scanning laser polarimetry with variable corneal compensation (GDxVCC), and the diagnostic capabilities of these imaging modalities were compared. RNFL parameters evaluated included superior average (Savg-GDx), inferior average (Iavg-GDx), temporal-superior-nasal- inferior-temporal (TSNIT) average, and nerve fiber indicator (NFI) on GDxVCC and superior average (Savg-OCT), inferior average (Iavg-OCT), nasal average (Navg-OCT), temporal average (Tavg-OCT), and average thickness (AvgThick-OCT) on OCT (fast RNFL scan). Visual field testing was performed and defects were evaluated using mean defect (MD) and pattern standard deviation (PSD). The RNFL parameters (P < 0.05) significantly different between groups included Savg-GDx, Iavg-GDx, TSNIT average, NFI, Savg-OCT, Iavg-OCT, Tavg-OCT, and AvgThick-OCT. Significant correlations existed between TSNIT average and AvgThick-OCT (r = 0.778), TSNIT average and MD (r = 0.749), AvgThick-OCT and MD (r = 0.647), TSNIT average and PSD (r = -0.756), and AvgThick-OCT and PSD (r = -0.784). The area under the receiver operating characteristic curve (AUROC) values of TSNIT average, Savg-GDx, Iavg-GDx, NFI, Savg-OCT, Iavg-OCT, Navg-OCT, Tavg-OCT, and AvgThick-OCT were 0.947, 0.962, 0.973, 0.994, 0.909, 0.917, 0.511, 0.906, and 0.913, respectively. The NFI AUROC was the

  19. Polarimetry

    Science.gov (United States)

    Nagendra, K. N.; Bagnulo, Stefano; Centeno, Rebecca; Jesús Martínez González, María.

    2015-08-01

    Preface; 1. Solar and stellar surface magnetic fields; 2. Future directions in astrophysical polarimetry; 3. Physical processes; 4. Instrumentation for astronomical polarimetry; 5. Data analysis techniques for polarization observations; 6. Polarization diagnostics of atmospheres and circumstellar environments; 7. Polarimetry as a tool for discovery science; 8. Numerical modeling of polarized emission; Author index.

  20. Structure-function relationship between the octopus perimeter cluster mean sensitivity and sector retinal nerve fiber layer thickness measured with the RTVue optical coherence tomography and scanning laser polarimetry.

    Science.gov (United States)

    Naghizadeh, Farzaneh; Garas, Anita; Vargha, Péter; Holló, Gábor

    2014-01-01

    To determine structure-function relationship between each of 16 Octopus perimeter G2 program clusters and the corresponding 16 peripapillary sector retinal nerve fiber layer thickness (RNFLT) values measured with the RTVue-100 Fourier-domain optical coherence tomography (RTVue OCT) and scanning laser polarimetry with variable corneal compensation (GDx-VCC) and enhanced corneal compensation (GDx-ECC) corneal compensation. One eye of 110 white patients (15 healthy, 20 ocular hypertensive, and 75 glaucoma eyes) were investigated. The Akaike information criterion and the F test were used to identify the best fitting model. Parabolic relationship with logarithmic cluster mean sensitivity and linear sector RNFLT values provided the best fit. For RTVue OCT, significant (P0.05) was found for the control eyes. Mean sensitivity of the Octopus visual field clusters showed significant parabolic relationship with the corresponding peripapillary RNFLT sectors. The relationship was more general with the RTVue OCT than GDx-VCC or GDx-ECC. The results show that visual field clusters of the Octopus G program can be applied for detailed structure-function research.

  1. Laser Compton polarimetry of proton beams

    International Nuclear Information System (INIS)

    Stillman, A.

    1995-01-01

    A need exists for non-destructive polarization measurements of the polarized proton beams in the AGS and, in the future, in RHIC. One way to make such measurements is to scatter photons from the polarized beams. Until now, such measurements were impossible because of the extremely low Compton scattering cross section from protons. Modern lasers now can provide enough photons per laser pulse not only to scatter from proton beams but also, at least in RHIC, to analyze their polarization

  2. Laser Scanning in Forests

    Directory of Open Access Journals (Sweden)

    Håkan Olsson

    2012-09-01

    Full Text Available The introduction of Airborne Laser Scanning (ALS to forests has been revolutionary during the last decade. This development was facilitated by combining earlier ranging lidar discoveries [1–5], with experience obtained from full-waveform ranging radar [6,7] to new airborne laser scanning systems which had components such as a GNSS receiver (Global Navigation Satellite System, IMU (Inertial Measurement Unit and a scanning mechanism. Since the first commercial ALS in 1994, new ALS-based forest inventory approaches have been reported feasible for operational activities [8–12]. ALS is currently operationally applied for stand level forest inventories, for example, in Nordic countries. In Finland alone, the adoption of ALS for forest data collection has led to an annual savings of around 20 M€/year, and the work is mainly done by companies instead of governmental organizations. In spite of the long implementation times and there being a limited tradition of making changes in the forest sector, laser scanning was commercially and operationally applied after about only one decade of research. When analyzing high-ranked journal papers from ISI Web of Science, the topic of laser scanning of forests has been the driving force for the whole laser scanning research society over the last decade. Thus, the topic “laser scanning in forests” has provided a significant industrial, societal and scientific impact. [...

  3. Comparison of particle size measurements of some aqueous suspensions by laser polarimetry and dynamic light scattering

    International Nuclear Information System (INIS)

    Chirikov, S N

    2016-01-01

    The results of the size distributions measurements of the particles of aqueous suspensions of ZnO, CuO, TiO 2 , and BaTiO 3 by methods of laser polarimetry and dynamic light scattering are considered. These measurements are compared with the results obtained by electron microscopy. It is shown that a laser polarimetry method gives more accurate results for size parameter values more than 1-2. (paper)

  4. A Study of Laser System Requirements for Application in Beam Diagnostics And Polarimetry at the ILC

    Energy Technology Data Exchange (ETDEWEB)

    Dixit, S.; Delerue, N.; Foster, B.; Howell, D.F.; Peach, K.; Quelch, G.; Qureshi, M.; Reichold, A.; /Oxford U.; Hirst, G.; Ross, I.; /Rutherford; Urakawa, J.; /KEK,; Soskov, V.; Variola, A.; Zomer, F.; /Orsay, LAL; Blair, G.A.; Boogert, S.T.; Boorman, G.; Bosco, A.; Driouichi, C.; Karataev, P.; /Royal Holloway, U. of London; Brachmann,; /SLAC

    2007-02-12

    Advanced laser systems will be essential for a range of diagnostics devices and polarimetry at the ILC. High average power, high beam quality, excellent stability and reliability will be crucial in order to deliver the information required to attain the necessary ILC luminosity as well as for efficient polarimetry. The key parameters are listed together with the R & D required to achieve the necessary laser system performance.

  5. Scanning laser Doppler vibrometry

    DEFF Research Database (Denmark)

    Brøns, Marie; Thomsen, Jon Juel

    With a Scanning Laser Doppler Vibrometer (SLDV) a vibrating surface is automatically scanned over predefined grid points, and data processed for displaying vibration properties like mode shapes, natural frequencies, damping ratios, and operational deflection shapes. Our SLDV – a PSV-500H from...

  6. Scanning Color Laser Microscope

    Science.gov (United States)

    Awamura, D.; Ode, T.; Yonezawa, M.

    1988-01-01

    A confocal color laser microscope which utilizes a three color laser light source (Red: He-Ne, Green: Ar, Blue: Ar) has been developed and is finding useful applications in the semiconductor field. The color laser microscope, when compared to a conventional microscope, offers superior color separation, higher resolution, and sharper contrast. Recently some new functions including a Focus Scan Memory, a Surface Profile Measurement System, a Critical Dimension Measurement system (CD) and an Optical Beam Induced Current Function (OBIC) have been developed for the color laser microscope. This paper will discuss these new features.

  7. Análise de Fourier para detecção de defeitos localizados na camada de fibras nervosas da retina com a polarimetria a laser Fourier analysis for the detection of localized nerve fiber layer defects using scanning laser polarimetry

    Directory of Open Access Journals (Sweden)

    Felipe Andrade Medeiros

    2003-12-01

    this study, we performed Fourier analysis of retinal nerve fiber layer (RNFL thickness measurements obtained with scanning laser polarimetry and evaluated the ability of this method to detect localized nerve fiber layer defects in glaucomatous patients. METHODS: The study included 40 eyes of 40 glaucomatous patients with localized RNFL defects identified by slit-lamp biomicroscopy or RNFL photography and 43 eyes of 43 normal patients. The patients were submitted to RNFL thickness measurements using the GDx® - Nerve Fiber Analyzer. Fourier analysis was applied to the polarimetry data. Fourier coefficients and GDx parameters were compared between the two groups. A linear discriminant function was developed to identify and combine the most useful Fourier coefficients to separate the two groups. ROC curves were obtained for each measurement and sensitivity values (at fixed specificities were calculated. RESULTS: The combination of Fourier coefficients resulted in a sensitivity of 80% for a specificity set at higher than 90%. For the same specificity, the GDx parameters had sensitivities ranging from 15% to 48%. The area under the ROC curve (AUC for the combination of Fourier coefficients was 0.90, significantly higher than the AUC for the parameter The Number (0.76. CONCLUSION: Fourier analysis of RNFL polarimetry data had a better diagnostic performance than standard GDx parameters to identify localized retinal nerve fiber layer defects in glaucomatous patients.

  8. Laser Compton polarimetry at JLab and MAMI. A status report

    International Nuclear Information System (INIS)

    Diefenbach, J.; Imai, Y.; Han Lee, J.; Maas, F.; Taylor, S.

    2007-01-01

    For modern parity violation experiments it is crucial to measure and monitor the electron beam polarization continuously. In the recent years different high-luminosity concepts, for precision Compton backscattering polarimetry, have been developed, to be used at modern CW electron beam accelerator facilities. As Compton backscattering polarimetry is free of intrinsic systematic uncertainties, it can be a superior alternative to other polarimetry techniques such as Moeller and Mott scattering. State-of-the-art high-luminosity Compton backscattering designs currently in use and under development at JLab and Mainz are compared to each other. The latest results from the Mainz A4 Compton polarimeter are presented. (orig.)

  9. Reprodutibilidade do exame de medida da camada de fibras nervosas da retina por meio da polarimetria de varredura a laser Reproducibility of retinal nerve fiber layer measurement by scanning laser polarimetry

    Directory of Open Access Journals (Sweden)

    Fernanda Bon Duarte

    1999-10-01

    ,02, nferior/temporal (p = 0,03 e temporal/nasal (p = 0,007 e superior/inferior (p = 0,037 e para as médias de espessura nos quadrantes inferior (p = 0,04 e temporal (p = 0,003. Conclusões: A análise dos dados indica ótima reprodutibilidade do exame intra-observador, e na avaliação inter-observador os melhores resultados de reprodutibilidade são obtidos quando a média das imagens fornecida pelo programa do equipamento é empregada.Purpose: To analyze the intra- and inter-observer reprodu-cibility of retinal fiber layer measurements. Methods: Twenty-six normal eyes underwent retinal nerve fiber layer thickness measurements with the GDx scanning system. Three images of each eye were taken by three different observers. For each case, each observer was asked to choose the best image and also to use the mean of the three images for each case. Comparisons were made using the best image and also the mean image provided by the software. The mean thickness values in each quadrant and their ratios were compared using Friedman rank analysis of variance. Results: The comparison of results obtained from the three images taken by the same observer (intraobserver reprodu-tibility did not show any statistically significant difference. The analysis of the data by the R (resident, T (technician and G (ophthalmologist specialized in glaucoma observers revealed respective-ly: pR( S = 0.89; I = 0.24; T = 0.89; N = 0.30, pT( S = 0.76; I = 0.70; T = 0.22; N = 0.63, and pG( S = 0.48; I = 0.89; T = 0.30; N = 0.89. Regarding the isolated values (superior, inferior, temporal and nasal, the analysis of the results considering the values obtained from the mean image did not reveal a statistically significant difference between the three investigators. But when relationships were considered a statistically significant difference was observed regarding the superior/inferior ratio (p S/I = 0.037. Statistically significant differences were detected when considering the best image. Inferior and

  10. Hyperchromatic laser scanning cytometry

    Science.gov (United States)

    Tárnok, Attila; Mittag, Anja

    2007-02-01

    In the emerging fields of high-content and high-throughput single cell analysis for Systems Biology and Cytomics multi- and polychromatic analysis of biological specimens has become increasingly important. Combining different technologies and staining methods polychromatic analysis (i.e. using 8 or more fluorescent colors at a time) can be pushed forward to measure anything stainable in a cell, an approach termed hyperchromatic cytometry. For cytometric cell analysis microscope based Slide Based Cytometry (SBC) technologies are ideal as, unlike flow cytometry, they are non-consumptive, i.e. the analyzed sample is fixed on the slide. Based on the feature of relocation identical cells can be subsequently reanalyzed. In this manner data on the single cell level after manipulation steps can be collected. In this overview various components for hyperchromatic cytometry are demonstrated for a SBC instrument, the Laser Scanning Cytometer (Compucyte Corp., Cambridge, MA): 1) polychromatic cytometry, 2) iterative restaining (using the same fluorochrome for restaining and subsequent reanalysis), 3) differential photobleaching (differentiating fluorochromes by their different photostability), 4) photoactivation (activating fluorescent nanoparticles or photocaged dyes), and 5) photodestruction (destruction of FRET dyes). With the intelligent combination of several of these techniques hyperchromatic cytometry allows to quantify and analyze virtually all components of relevance on the identical cell. The combination of high-throughput and high-content SBC analysis with high-resolution confocal imaging allows clear verification of phenotypically distinct subpopulations of cells with structural information. The information gained per specimen is only limited by the number of available antibodies and by sterical hindrance.

  11. Morphological characteristics of the optic nerve evaluated by confocal laser tomography (HRT3) and laser polarimetry (GDx-VCC) in a normal population from the city of Barcelona.

    Science.gov (United States)

    Fallon, M; Pazos, M; Morilla, A; Sebastián, M A; Xancó, R; Mora, C; Calderón, B; Vega, Z; Antón, A

    2015-11-01

    To evaluate morphological parameters of optic disc and retinal nerve fiber layer (RNFL) examined with confocal laser tomography (HRT3) and laser polarimetry (GDx-VCC) in a normal population, and analyze correlations of these parameters with demographic variables. Cross-sectional study in the context of a glaucoma screening campaign in the primary care center of Barcelona. The individuals selected were non-hypertensive Mediterranean Caucasians with risk for glaucoma development (individuals≥60 years old or≥40 years old with family history of glaucoma or intraocular pressure or myopia>3diopter). All subjects underwent a complete ophthalmic examination, confocal laser tomography (HRT3) and scanning laser polarimetry (GDX-VCC), subjects with results within normal limits only being included. Structural parameters were analyzed along with age, refraction, and pachymetry based on the Spearman rank correlation test. A total of 224 subjects included, with a mean age of 63.4±11.1 years. Disc areas, excavation and ring area were 2.14±0.52mm(2), 0.44±0.34mm (2) and 1.69±0.38mm(2), respectively. The mean RNFL (GDX) was 55.9±6.9μm. Age was correlated with lower ring volume, highest rate of cup shape measure, largest mean and maximum cup depth, lower nerve fiber index (NFI) and RNFL (all p-values below .05). The mean values and distribution of several parameters of the papilla and the RNFL in normal Mediterranean Caucasians population are presented. A loss of thickness of the RNFL, ring thinning, and enlarged cup was observed with increased age. Copyright © 2014 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  12. Scanning laser polarimetry in eyes with exfoliation syndrome.

    Science.gov (United States)

    Dimopoulos, Antonios T; Katsanos, Andreas; Mikropoulos, Dimitrios G; Giannopoulos, Theodoros; Empeslidis, Theodoros; Teus, Miguel A; Holló, Gábor; Konstas, Anastasios G P

    2013-01-01

    To compare retinal nerve fiber layer thickness (RNFLT) of normotensive eyes with exfoliation syndrome (XFS) and healthy eyes.
 Sixty-four consecutive individuals with XFS and normal office-time intraocular pressure (IOP) and 72 consecutive healthy controls were prospectively enrolled for a cross-sectional analysis in this hospital-based observational study. The GDx-VCC parameters (temporal-superior-nasal-inferior-temporal [TSNIT] average, superior average, inferior average, TSNIT standard deviation (SD), and nerve fiber indicator [NFI]) were compared between groups. Correlation between various clinical parameters and RNFLT parameters was investigated with Spearman coefficient. 
 The NFI, although within normal limits for both groups, was significantly greater in the XFS group compared to controls: the respective median and interquartile range (IQR) values were 25.1 (22.0-29.0) vs 15.0 (12.0-20.0), ppolarimetry-determined RNFLT was lower in XFS eyes with normal IOP. Therefore, close monitoring of RNFLT may facilitate early identification of those XFS eyes that convert to exfoliative glaucoma.

  13. Sensitivity and specificity of scanning laser polarimetry using the GDx.

    Science.gov (United States)

    Munkwitz, S; Funk, J; Loeffler, K U; Harbarth, U; Kremmer, S

    2004-09-01

    To determine the sensitivity and the specificity of the GDx in the detection of (1) advanced glaucoma, (2) early glaucoma, and (3) nerve fibre bundle defects (NFBD). Group A comprised 20 eyes with reproducible glaucomatous visual field defects confirmed by octopus perimetry, group B consisted of 10 eyes with normal visual fields but either glaucomatous NFBD or deterioration of the disc over time clearly visible upon flicker comparison, and group C included 16 eyes with glaucomatous or non-glaucomatous NFBD clearly visible on red free photographs. Forty four eyes of 22 healthy volunteers served as controls. The GDx printouts of all subjects were evaluated by three independent observers in a masked fashion and without the clinical picture of the optic disc. Two of the three observers (SK, UH) were GDx experts, one (KUL) was an untrained GDx user. Among the GDx experts, sensitivity/specificity was 100%/100% (SK) and 90%/100% (UH) in detecting advanced glaucoma, and 100%/100% (SK) and 90%/100% (UH) in detecting early glaucoma. The sensitivity in detecting NFBD was only 37.5% (SK and UH). For the untrained GDx user the corresponding values were 50%/100% (group A), 20%/100% (group B), and 12.5%/91% (group C). Detection of (early) glaucoma damage by the GDx, evaluated by trained experts, can be extremely high. To optimise its benefit in clinical routine training in interpreting GDx printouts is highly recommended. Detection of localised NFBD is crucial, even for experts.

  14. Influência da redução medicamentosa da pressão intra-ocular na medida da espessura da camada de fibras nervosas da retina de olhos hipertensos e glaucomatosos pela polarimetria de varredura a laser The influence of intraocular pressure reduction with medication on retinal nerve fiber layer thickness measurements obtained with scanning laser polarimetry in glaucomatous and hypertensive eyes

    Directory of Open Access Journals (Sweden)

    Rodrigo Rezende Gomes Avelino

    2006-10-01

    Full Text Available OBJETIVO: Avaliar o efeito da redução da pressão intra-ocular (PIO obtido com o uso de terapia medicamentosa na espessura da camada de fibras nervosas da retina medida pela polarimetria de varredura a laser (PVL em pacientes glaucomatosos ou hipertensos oculares. MÉTODOS: Trinta e sete olhos de 37 pacientes foram prospectivamente incluídos no estudo e avaliados com a PVL sem uso de medicação ocular hipotensora e num período entre 15 e 30 dias após a instituição de medicação ocular hipotensora, que resultou em redução da PIO de pelo menos 25%. Os parâmetros medidos pela PVL antes e após a redução da PIO foram comparados com o teste t de Student pareado. RESULTADOS: A PIO média dos 37 pacientes diminuiu significativamente de 26,57±4,23 mmHg para 16,54±2,92 mmHg (p0,05. CONCLUSÃO: A redução da PIO com o uso de medicação ocular hipotensora não altera a medida da espessura da camada de fibras nervosas da retina pela PVL em pacientes com glaucoma ou hipertensão ocular.PURPOSE: To evaluate changes in retinal nerve fiber layer thickness as measured by scanning laser polarimetry (SLP after the use of medication to reduce intraocular pressure (IOP in glaucomatous or ocular hypertensive patients. METHODS: The authors prospectively enrolled 37 eyes of 37 patients in whom IOP was reduced by more than 25% after the use of medication. The images were obtained before and 15 to 30 days after the introduction of medication. The SLP parameters measured before and after the use of medication were compared using paired Student's t Test. RESULTS: The mean IOP was significantly reduced from 26.57±4.23 mmHg to 16.54 ±2.92 mmHg after the use of medication (p0.05. CONCLUSION: The retinal nerve fiber layer thickness, as measured by SLP, is not affected by the reduction of IOP with medication in patients with glaucoma or ocular hypertension.

  15. Handbook of optical and laser scanning

    CERN Document Server

    Marshall, Gerald F

    2011-01-01

    From its initial publication titled Laser Beam Scanning in 1985 to Handbook of Optical and Laser Scanning, now in its second edition, this reference has kept professionals and students at the forefront of optical scanning technology. Carefully and meticulously updated in each iteration, the book continues to be the most comprehensive scanning resource on the market. It examines the breadth and depth of subtopics in the field from a variety of perspectives. The Second Edition covers: Technologies such as piezoelectric devices Applications of laser scanning such as Ladar (laser radar) Underwater

  16. QUANTITATIVE CONFOCAL LASER SCANNING MICROSCOPY

    Directory of Open Access Journals (Sweden)

    Merete Krog Raarup

    2011-05-01

    Full Text Available This paper discusses recent advances in confocal laser scanning microscopy (CLSM for imaging of 3D structure as well as quantitative characterization of biomolecular interactions and diffusion behaviour by means of one- and two-photon excitation. The use of CLSM for improved stereological length estimation in thick (up to 0.5 mm tissue is proposed. The techniques of FRET (Fluorescence Resonance Energy Transfer, FLIM (Fluorescence Lifetime Imaging Microscopy, FCS (Fluorescence Correlation Spectroscopy and FRAP (Fluorescence Recovery After Photobleaching are introduced and their applicability for quantitative imaging of biomolecular (co-localization and trafficking in live cells described. The advantage of two-photon versus one-photon excitation in relation to these techniques is discussed.

  17. Laser scanning of experimental solar cells

    Science.gov (United States)

    Plunkett, B. C.; Lasswell, P. G.

    1980-01-01

    A description is presented of a laser scanning instrument which makes it possible to display and measure the spatial response of a solar cell. Examples are presented to illustrate the use of generated micrographs in the isolation of flaws and features of the cell. The laser scanner system uses a 4 mW, CW helium-neon laser, operating a wavelength of 0.633 micrometers. The beam is deflected by two mirror galvanometers arranged to scan in orthogonal directions. After being focused on the solar cell by the beam focusing lens, the moving light spot raster scans the specimen. The current output of the photovoltaic device under test, as a function of the scan dot position, can be displayed in several modes. The laser scanner has proved to be a very useful diagnostic tool in optimizing the process design of transparent metal film photovoltaic devices on Zn3P2, a relatively new photovoltaic material.

  18. Multicolor Scanning Laser Imaging in Diabetic Retinopathy.

    Science.gov (United States)

    Ahmad, Mohammad S Z; Carrim, Zia Iqbal

    2017-11-01

    Diabetic retinopathy is a common cause of blindness in individuals younger than 60 years. Screening for retinopathy is undertaken using conventional color fundus photography and relies on the identification of hemorrhages, vascular abnormalities, exudates, and cotton-wool spots. These can sometimes be difficult to identify. Multicolor scanning laser imaging, a new imaging modality, may have a role in improving screening outcomes, as well as facilitating treatment decisions. Observational case series comprising two patients with known diabetes who were referred for further examination after color fundus photography revealed abnormal findings. Multicolor scanning laser imaging was undertaken. Features of retinal disease from each modality were compared. Multicolor scanning laser imaging provides superior visualization of retinal anatomy and pathology, thereby facilitating risk stratification and treatment decisions. Multicolor scanning laser imaging is a novel imaging technique offering the potential for improving the reliability of screening for diabetic retinopathy. Validation studies are warranted.

  19. Laser scanning camera inspects hazardous area

    International Nuclear Information System (INIS)

    Fryatt, A.; Miprode, C.

    1985-01-01

    Main operational characteristics of a new laser scanning camera are presented. The camera is intended primarily for low level high resolution viewing inside nuclear reactors. It uses a He-Ne laser beam raster; by detecting the reflected light by means of a phomultiplier, the subject under observation can be reconstructed in an electronic video store and reviewed on a conventional monitor screen

  20. Scanning laser microscope for imaging nanostructured superconductors

    International Nuclear Information System (INIS)

    Ishida, Takekazu; Arai, Kohei; Akita, Yukio; Miyanari, Mitsunori; Minami, Yusuke; Yotsuya, Tsutomu; Kato, Masaru; Satoh, Kazuo; Uno, Mayumi; Shimakage, Hisashi; Miki, Shigehito; Wang, Zhen

    2010-01-01

    The nanofabrication of superconductors yields various interesting features in superconducting properties. A variety of different imaging techniques have been developed for probing the local superconducting profiles. A scanning pulsed laser microscope has been developed by the combination of the XYZ piezo-driven stages and an optical fiber with an aspheric focusing lens. The scanning laser microscope is used to understand the position-dependent properties of a superconducting MgB 2 stripline of length 100 μm and width of 3 μm under constant bias current. Our results show that the superconducting stripline can clearly be seen in the contour image of the scanning laser microscope on the signal voltage. It is suggested from the observed image that the inhomogeneity is relevant in specifying the operating conditions such as detection efficiency of the sensor.

  1. Scanning laser microscope for imaging nanostructured superconductors

    Science.gov (United States)

    Ishida, Takekazu; Arai, Kohei; Akita, Yukio; Miyanari, Mitsunori; Minami, Yusuke; Yotsuya, Tsutomu; Kato, Masaru; Satoh, Kazuo; Uno, Mayumi; Shimakage, Hisashi; Miki, Shigehito; Wang, Zhen

    2010-10-01

    The nanofabrication of superconductors yields various interesting features in superconducting properties. A variety of different imaging techniques have been developed for probing the local superconducting profiles. A scanning pulsed laser microscope has been developed by the combination of the XYZ piezo-driven stages and an optical fiber with an aspheric focusing lens. The scanning laser microscope is used to understand the position-dependent properties of a superconducting MgB 2 stripline of length 100 μm and width of 3 μm under constant bias current. Our results show that the superconducting stripline can clearly be seen in the contour image of the scanning laser microscope on the signal voltage. It is suggested from the observed image that the inhomogeneity is relevant in specifying the operating conditions such as detection efficiency of the sensor.

  2. RADIOMETRIC CALIBRATION OF AIRBORNE LASER SCANNING DATA

    OpenAIRE

    Pilarska Magdalena

    2016-01-01

    Airborne laser scanning (ALS) is widely used passive remote sensing technique. The radiometric calibration of ALS data is presented in this article. This process is a necessary element in data processing since it eliminates the influence of the external factors on the obtained values of radiometric features such as range and incidence angle. The datasets were captured with three different laser scanners; since each of these operates at a different wavelength (532, 106 4 and 1550 nm) th...

  3. Multiplatform Mobile Laser Scanning: Usability and Performance

    Directory of Open Access Journals (Sweden)

    Yuwei Chen

    2012-08-01

    Full Text Available Mobile laser scanning is an emerging technology capable of capturing three-dimensional data from surrounding objects. With state-of-the-art sensors, the achieved point clouds capture object details with good accuracy and precision. Many of the applications involve civil engineering in urban areas, as well as traffic and other urban planning, all of which serve to make 3D city modeling probably the fastest growing market segment in this field. This article outlines multiplatform mobile laser scanning solutions such as vehicle- and trolley-operated urban area data acquisition, and boat-mounted equipment for fluvial environments. Moreover, we introduce a novel backpack version of mobile laser scanning equipment for surveying applications in the field of natural sciences where the requirements include precision and mobility in variable terrain conditions. In addition to presenting a technical description of the systems, we discuss the performance of the solutions in the light of various applications in the fields of urban mapping and modeling, fluvial geomorphology, snow-cover characterization, precision agriculture, and in monitoring the effects of climate change on permafrost landforms. The data performance of the mobile laser scanning approach is described by the results of an evaluation of the ROAMER on a permanent MLS test field. Furthermore, an in situ accuracy assessment using a field of spherical 3D targets for the newly-introduced Akhka backpack system is conducted and reported on.

  4. Polarized differential-phase laser scanning microscope

    International Nuclear Information System (INIS)

    Chou Chien; Lyu, C.-W.; Peng, L.-C.

    2001-01-01

    A polarized differential-phase laser scanning microscope, which combines a polarized optical heterodyne Mach-Zehnder interferometer and a differential amplifier to scan the topographic image of a surface, is proposed. In the experiment the differential amplifier, which acts as a PM-AM converter, in the experiment, converting phase modulation (PM) into amplitude modulation (AM). Then a novel, to our knowledge, phase demodulator was proposed and implemented for the differential-phase laser scanning microscope. An optical grating (1800 lp/mm) was imaged. The lateral and the depth resolutions of the imaging system were 0.5 μm and 1 nm, respectively. The detection accuracy, which was limited by the reflectivity variation of the test surface, is discussed

  5. Imaging Polarimetry in Age-Related Macular Degeneration

    Science.gov (United States)

    Miura, Masahiro; Yamanari, Masahiro; Iwasaki, Takuya; Elsner, Ann E.; Makita, Shuichi; Yatagai, Toyohiko; Yasuno, Yoshiaki

    2010-01-01

    PURPOSE To evaluate the birefringence properties of eyes with age-related macular degeneration (AMD). To compare the information from two techniques—scanning laser polarimetry (GDx) and polarization-sensitive spectral-domain optical coherence tomography (OCT)—and investigate how they complement each other. METHODS The authors prospectively examined the eyes of two healthy subjects and 13 patients with exudative AMD. Using scanning laser polarimetry, they computed phase-retardation maps, average reflectance images, and depolarized light images. To obtain polarimetry information with improved axial resolution, they developed a fiber-based, polarization-sensitive, spectral-domain OCT system and measured the phase retardation associated with birefringence in the same eyes. RESULTS Both GDx and polarization-sensitive spectral-domain optical coherence tomography detected abnormal birefringence at the locus of exudative lesions. Polarization-sensitive, spectral-domain OCT showed that in the old lesions with fibrosis, phase-retardation values were significantly larger than in the new lesions (P = 0.020). Increased scattered light and altered polarization scramble were associated with portions of the lesions. CONCLUSIONS GDx and polarization-sensitive spectral-domain OCT are complementary in probing birefringence properties in exudative AMD. Polarimetry findings in exudative AMD emphasized different features and were related to the progression of the disease, potentially providing a noninvasive tool for microstructure in exudative AMD. PMID:18515594

  6. Scanning laser ophthalmoscope design with adaptive optics

    OpenAIRE

    Laut, SP; Jones, SM; Olivier, SS; Werner, JS

    2005-01-01

    A design for a high-resolution scanning instrument is presented for in vivo imaging of the human eye at the cellular scale. This system combines adaptive optics technology with a scanning laser ophthalmoscope (SLO) to image structures with high lateral (∼2 μm) resolution. In this system, the ocular wavefront aberrations that reduce the resolution of conventional SLOs are detected by a Hartmann-Shack wavefront sensor, and compensated with two deformable mirrors in a closed-loop for dynamic cor...

  7. Mobile Laser Scanning for Indoor Modelling

    Directory of Open Access Journals (Sweden)

    C. Thomson

    2013-10-01

    Full Text Available The process of capturing and modelling buildings has gained increased focus in recent years with the rise of Building Information Modelling (BIM. At the heart of BIM is a process change for the construction and facilities management industries whereby a BIM aids more collaborative working through better information exchange, and as a part of the process Geomatic/Land Surveyors are not immune from the changes. Terrestrial laser scanning has been proscribed as the preferred method for rapidly capturing buildings for BIM geometry. This is a process change from a traditional measured building survey just with a total station and is aided by the increasing acceptance of point cloud data being integrated with parametric building models in BIM tools such as Autodesk Revit or Bentley Architecture. Pilot projects carried out previously by the authors to investigate the geometry capture and modelling of BIM confirmed the view of others that the process of data capture with static laser scan setups is slow and very involved requiring at least two people for efficiency. Indoor Mobile Mapping Systems (IMMS present a possible solution to these issues especially in time saved. Therefore this paper investigates their application as a capture device for BIM geometry creation over traditional static methods through a fit-for-purpose test.

  8. Mobile Laser Scanning for Indoor Modelling

    Science.gov (United States)

    Thomson, C.; Apostolopoulos, G.; Backes, D.; Boehm, J.

    2013-10-01

    The process of capturing and modelling buildings has gained increased focus in recent years with the rise of Building Information Modelling (BIM). At the heart of BIM is a process change for the construction and facilities management industries whereby a BIM aids more collaborative working through better information exchange, and as a part of the process Geomatic/Land Surveyors are not immune from the changes. Terrestrial laser scanning has been proscribed as the preferred method for rapidly capturing buildings for BIM geometry. This is a process change from a traditional measured building survey just with a total station and is aided by the increasing acceptance of point cloud data being integrated with parametric building models in BIM tools such as Autodesk Revit or Bentley Architecture. Pilot projects carried out previously by the authors to investigate the geometry capture and modelling of BIM confirmed the view of others that the process of data capture with static laser scan setups is slow and very involved requiring at least two people for efficiency. Indoor Mobile Mapping Systems (IMMS) present a possible solution to these issues especially in time saved. Therefore this paper investigates their application as a capture device for BIM geometry creation over traditional static methods through a fit-for-purpose test.

  9. Compton Polarimetry at ELSA

    International Nuclear Information System (INIS)

    Hillert, Wolfgang; Aurand, Bastian; Wittschen, Juergen

    2009-01-01

    Part of the future polarization program performed at the Bonn accelerator facility ELSA will rely on precision Compton polarimetry of the stored transversely polarized electron beam. Precise and fast polarimetry poses high demands on the light source and the detector which were studied in detail performing numerical simulations of the Compton scattering process. In order to experimentally verify these calculations, first measurements were carried out using an argon ion laser as light source and a prototype version of a counting silicon microstrip detector. Calculated and measured intensity profiles of backscattered photons are presented and compared, showing excellent agreement. Background originating from beam gas radiation turned out to be the major limitation of the polarimeter performance. In order to improve the situation, a new polarimeter was constructed and is currently being set up. Design and expected performance of this polarimeter upgrade are presented.

  10. 2. Interferometry and polarimetry. 2.1. Principle of interferometry and polarimetry

    International Nuclear Information System (INIS)

    Kawahata, Kazuo; Okajima, Shigeki

    2000-01-01

    Laser interferometry and polarimetry are useful diagnostics for measuring electron density and the internal magnetic field distribution in the plasma. In this section, principles of interferometry and polarimetry and their applications to plasma diagnostics on LHD (section 2.2) and JT-60 (section 2.3) are descried. (author)

  11. Evaluation of 3-D Laser Scanning Equipment : 2018 Final Report

    Science.gov (United States)

    2018-05-01

    As a follow-up to ICT Project R27-030, Evaluation of 3-D Laser Scanning, this report provides findings of an evaluation of 3-D laser scanning equipment to determine the tangible costs versus benefits and the manpower savings realized by using the equ...

  12. Structural monitoring of tunnels using terrestrial laser scanning

    NARCIS (Netherlands)

    Lindenbergh, R.C.; Uchanski, L.; Bucksch, A.; Van Gosliga, R.

    2009-01-01

    In recent years terrestrial laser scanning is rapidly evolving as a surveying technique for the monitoring of engineering objects like roof constructions, mines, dams, viaducts and tunnels. The advantage of laser scanning above traditional surveying methods is that it allows for the rapid

  13. Heterodyne polarimetry technology for inspection of critical dimensions

    Directory of Open Access Journals (Sweden)

    Protopopov V.

    2010-06-01

    Full Text Available Heterodyne polarimetry is based on the analysis of phases and polarization states of two frequency shifted cross-polarized waves, generated by Zeeman lasers and their analogs [1]. In semiconductor industry, manufacturing of memory chips depends on the width and aspect ratio of a great number of identical parallel vertical and horizontal word and bit address lines. Such a structure may be considered as a wire grid polarizer for visible optics, and it is reasonable to expect that polarimetry techniques may be efficient for detecting tiny variations in this type of structures on masks and wafers. Currently, both imaging and non-imaging modalities are considered as complementary inspection technologies. The talk will focus on instrumentation, theory, and experimental results of two different inspection tools: scanning polarimeters for mapping variations of critical dimensions over lithography masks and semiconductor wafers, and polarization-controlled dual-channel heterodyne microscope with super-resolution capabilities.

  14. Stellar Polarimetry

    CERN Document Server

    Clarke, David

    2009-01-01

    Written by an experienced teacher and author, this must-have source for work with polarimetric equipment and polarimetry in astronomy conveys the knowledge of the technology and techniques needed to measure and interpret polarizations. As such, this monograph offers a brief introduction and refresher, while also covering in detail statistics and data treatment as well as telescope optics. For astronomers, physicists and those working in the optical industry.

  15. Laser safety in design of near-infrared scanning LIDARs

    Science.gov (United States)

    Zhu, X.; Elgin, D.

    2015-05-01

    3D LIDARs (Light Detection and Ranging) with 1.5μm nanosecond pulse lasers have been increasingly used in different applications. The main reason for their popularity is that these LIDARs have high performance while at the same time can be made eye-safe. Because the laser hazard effect on eyes or skin at this wavelength region (industrial mining applications. We have incorporated the laser safety requirements in the LIDAR design and conducted laser safety analysis for different operational scenarios. While 1.5μm is normally said to be the eye-safe wavelength, in reality a high performance 3D LIDAR needs high pulse energy, small beam size and high pulse repetition frequency (PRF) to achieve long range, high resolution and high density images. The resulting radiant exposure of its stationary beam could be many times higher than the limit for a Class 1 laser device. Without carefully choosing laser and scanning parameters, including field-of-view, scan speed and pattern, a scanning LIDAR can't be eye- or skin-safe based only on its wavelength. This paper discusses the laser safety considerations in the design of eye-safe scanning LIDARs, including laser pulse energy, PRF, beam size and scanning parameters in two basic designs of scanning mechanisms, i.e. galvanometer based scanner and Risley prism based scanner. The laser safety is discussed in terms of device classification, nominal ocular hazard distance (NOHD) and safety glasses optical density (OD).

  16. Application of Confocal Laser Scanning Microscopy in Biology and Medicine

    OpenAIRE

    I. A. Volkov; N. V. Frigo; L. F. Znamenskaya; O. R. Katunina

    2014-01-01

    Fluorescence confocal laser scanning microscopy and reflectance confocal laser scanning microscopy are up-to-date highend study methods. Confocal microscopy is used in cell biology and medicine. By using confocal microscopy, it is possible to study bioplasts and localization of protein molecules and other compounds relative to cell or tissue structures, and to monitor dynamic cell processes. Confocal microscopes enable layer-by-layer scanning of test items to create demonstrable 3D models. As...

  17. A laser sheet self-calibration method for scanning PIV

    Science.gov (United States)

    Knutsen, Anna N.; Lawson, John M.; Dawson, James R.; Worth, Nicholas A.

    2017-10-01

    Knowledge of laser sheet position, orientation, and thickness is a fundamental requirement of scanning PIV and other laser-scanning methods. This paper describes the development and evaluation of a new laser sheet self-calibration method for stereoscopic scanning PIV, which allows the measurement of these properties from particle images themselves. The approach is to fit a laser sheet model by treating particles as randomly distributed probes of the laser sheet profile, whose position is obtained via a triangulation procedure enhanced by matching particle images according to their variation in brightness over a scan. Numerical simulations and tests with experimental data were used to quantify the sensitivity of the method to typical experimental error sources and validate its performance in practice. The numerical simulations demonstrate the accurate recovery of the laser sheet parameters over range of different seeding densities and sheet thicknesses. Furthermore, they show that the method is robust to significant image noise and camera misalignment. Tests with experimental data confirm that the laser sheet model can be accurately reconstructed with no impairment to PIV measurement accuracy. The new method is more efficient and robust in comparison with the standard (self-) calibration approach, which requires an involved, separate calibration step that is sensitive to experimental misalignments. The method significantly improves the practicality of making accurate scanning PIV measurements and broadens its potential applicability to scanning systems with significant vibrations.

  18. Maritime Laser Scanning as the Source for Spatial Data

    Directory of Open Access Journals (Sweden)

    Szulwic Jakub

    2015-12-01

    Full Text Available The rapid development of scanning technology, especially mobile scanning, gives the possibility to collect spatial data coming from maritime measurement platforms and autonomous manned or unmanned vehicles. Presented solution is derived from the mobile scanning. However we should keep in mind that the specificity of laser scanning at sea and processing collected data should be in the form acceptable in Geographical Information Systems, especially typical for the maritime needs. At the same time we should be aware that data coming from maritime mobile scanning constitutes a new approach to the describing of maritime environment and brings a new perspective that is completely different than air and terrestrial scanning.

  19. SAR Polarimetry

    Science.gov (United States)

    vanZyl, Jakob J.

    2012-01-01

    Radar Scattering includes: Surface Characteristics, Geometric Properties, Dielectric Properties, Rough Surface Scattering, Geometrical Optics and Small Perturbation Method Solutions, Integral Equation Method, Magellan Image of Pancake Domes on Venus, Dickinson Impact Crater on Venus (Magellan), Lakes on Titan (Cassini Radar, Longitudinal Dunes on Titan (Cassini Radar), Rough Surface Scattering: Effect of Dielectric Constant, Vegetation Scattering, Effect of Soil Moisture. Polarimetric Radar includes: Principles of Polarimetry: Field Descriptions, Wave Polarizations: Geometrical Representations, Definition of Ellipse Orientation Angles, Scatter as Polarization Transformer, Scattering Matrix, Coordinate Systems, Scattering Matrix, Covariance Matrix, Pauli Basis and Coherency Matrix, Polarization Synthesis, Polarimeter Implementation.

  20. IR and FIR laser polarimetry as a diagnostic tool in high-. beta. and Tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, D; Machida, M; Scalabrin, A

    1986-03-01

    The change of the polarization state of an electromagnetic wave (EMW) propagating across a magnetized plasma may be used to determine plasma parameters. In a plasma machine of the Tokamak type, the Faraday rotation of the EMW allows for the determination of the product of the plasma electronic density by the poloidal magnetic field. A novel optical configuration which permits simultaneous measurements of these two parameters without the use of an auxiliary interferometric set up is proposed. By choosing appropriate laser wave length this method can be used in Tokamaks (lambda >= 1mm) and also in theta-pinch plasmas (lambda approx. 10..mu..m). The application of these results is discussed to plasma machines now in operation in Brazil, like the Tokamak/USP and theta-pinch/UNICAMP, using lasers developed at UNICAMP.

  1. New possibilities for using laser polarimetry technology to study electron paramagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, E V; Zapasskii, V S

    1982-01-01

    Optical methods of recording electron paramagnetic resonance which arose in the early 50's as applied to the problem of recording the magnetic resonance of excited atoms is at the present time widely used in studying the electron paramagnetic resonance of the ground and excited states of free atoms and paramagnetic centers in condensed media. At the present time attention is devoted to the additional possibilities of optical methods of electron paramagnetic resonance which are realized using laser sources.

  2. Shot-noise-limited optical Faraday polarimetry with enhanced laser noise cancelling

    International Nuclear Information System (INIS)

    Li, Jiaming; Luo, Le; Carvell, Jeff; Cheng, Ruihua; Lai, Tianshu; Wang, Zixin

    2014-01-01

    We present a shot-noise-limited measurement of optical Faraday rotations with sub-ten-nanoradian angular sensitivity. This extremely high sensitivity is achieved by using electronic laser noise cancelling and phase sensitive detection. Specially, an electronic laser noise canceller with a common mode rejection ratio of over 100 dB was designed and built for enhanced laser noise cancelling. By measuring the Faraday rotation of ambient air, we demonstrate an angular sensitivity of up to 9.0×10 −9  rad/√(Hz), which is limited only by the shot-noise of the photocurrent of the detector. To date, this is the highest angular sensitivity ever reported for Faraday polarimeters in the absence of cavity enhancement. The measured Verdet constant of ambient air, 1.93(3)×10 −9 rad/(G cm) at 633 nm wavelength, agrees extremely well with the earlier experiments using high finesse optical cavities. Further, we demonstrate the applications of this sensitive technique in materials science by measuring the Faraday effect of an ultrathin iron film

  3. Power Measurements for Microvision, Inc., Aircrew Integrated Helmet System Scanning Laser Helmet-Mounted Display

    National Research Council Canada - National Science Library

    Rash, Clarence

    2002-01-01

    ...) technology based on scanning lasers. Under this program, Microvision, Inc., Bothell, Washington, has developed a scanning laser HMD prototype for use with the Aircrew Integrated Helmet System (AIHS...

  4. Structure, function and progression analysis in glaucoma : a study with scanning laser polarimetry

    NARCIS (Netherlands)

    Mai, Thê' Anh

    2008-01-01

    Glaucoma is currently a serious global challenge. It is the second leading cause of blindness worldwide after cataract, and accounts for up to 12.3 % of all blindness (i.e., approximately 4.5 million people). As the size of the world population aged 50 years or older increases, the number of people,

  5. Application of Stark Tuned Laser for Interferometry and Polarimetry in Plasmas

    International Nuclear Information System (INIS)

    H.K. Park; K.C. Lee; B. Deng; C.W. Domier; M. Johnson; B. Nathan; N.C. Luhmann, Jr.

    2001-01-01

    A Stark-tuned optically pumped far-infrared CH(subscript ''3'')OH laser at 119 mm has been successfully applied in the Far Infrared Tangential Interferometer/Polarimeter (FIReTIP) system for the National Spherical Torus Experiment (NSTX). The system will provide temporally and radially resolved 2-D electron density profile [n(subscript ''e'')(r,t)] and toroidal field profile [B(subscript ''T'')(r,t)] data. In the 2001 campaign, a single channel interferometer system has been operated and tested for the Faraday rotation measurement. A plan for improvement and upgrading of the FIReTIP is discussed

  6. scanning speed influence on the physical properties of laser metal

    African Journals Online (AJOL)

    user

    2017-01-01

    Jan 1, 2017 ... result of the preliminary study that produces full dense and pore free deposits. ... Keywords: Additive manufacturing, Laser metal deposition (LMD), Material efficiency, Titanium alloy. 1. ... parts. Ti6Al4V is the most commonly produced titanium alloy ... In this study, effect of laser transverse speed or scanning.

  7. Multicolor pattern scan laser for diabetic retinopathy with cataract

    Institute of Scientific and Technical Information of China (English)

    Takao; Hirano; Yasuhiro; Iesato; Toshinori; Murata

    2014-01-01

    · AIM: To evaluate the ability of various laser wavelengths in delivering sufficient burns to the retina in eyes with cataract using a new multicolor pattern scan laser with green(532 nm), yellow(577 nm), and red(647 nm)lasers.·METHODS: The relationship between the Emery-Little(EL) degree of cataract severity and the laser wavelength required to deliver adequate burns was investigated in102 diabetic eyes. Treatment time, total number of laser shots, and intra-operative pain were assessed as well.·RESULTS: All EL-1 grade eyes and 50% of EL-2 eyes were successfully treated with the green laser, while 50%of EL-2 eyes, 96% of EL-3 eyes, and 50% of EL-4 eyes required the yellow laser. The red laser was effective in the remaining 4% of EL-3 and 50% of EL-4 eyes.·CONCLUSION: Longer wavelength lasers are more effective in delivering laser burns through cataract when we use a multicolor pattern scan laser system.

  8. Facial recognition and laser surface scan: a pilot study

    DEFF Research Database (Denmark)

    Lynnerup, Niels; Clausen, Maja-Lisa; Kristoffersen, Agnethe May

    2009-01-01

    Surface scanning of the face of a suspect is presented as a way to better match the facial features with those of a perpetrator from CCTV footage. We performed a simple pilot study where we obtained facial surface scans of volunteers and then in blind trials tried to match these scans with 2D...... photographs of the faces of the volunteers. Fifteen male volunteers were surface scanned using a Polhemus FastSCAN Cobra Handheld Laser Scanner. Three photographs were taken of each volunteer's face in full frontal, profile and from above at an angle of 45 degrees and also 45 degrees laterally. Via special...

  9. Evolution of laser skin resurfacing: from scanning to fractional technology.

    Science.gov (United States)

    Aslam, Arif; Alster, Tina S

    2014-11-01

    Laser skin resurfacing was popularized for photoaged and scarred skin 2 decades ago. Since then, several technologic advancements have led to a new generation of delivery systems that produce excellent clinical outcomes with reduced treatment risks and faster recovery times. To review the evolution of laser skin resurfacing from pulsed and scanned infrared laser technology to the latest techniques of nonablative and ablative fractional photothermolysis. All published literature regarding laser skin resurfacing was analyzed and collated. A comprehensive review of laser skin resurfacing was outlined and future developments in the field of fractionated laser skin treatment were introduced. Laser skin resurfacing has evolved such that excellent clinical outcomes in photodamaged and scarred skin are achieved with rapid wound healing. As newer devices are developed, the applications of this technology will have a dramatic effect on the delivery of medical and aesthetic dermatology.

  10. Influence of laser frequency noise on scanning Fabry-Perot interferometer based laser Doppler velocimetry

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Pedersen, Christian

    2014-01-01

    n this work, we study the performance of a scanning Fabry-Perot interferometer based laser Doppler velocimeter (sFPILDV) and compare two candidate 1.5 um single-frequency laser sources for the system – a fiber laser (FL) and a semiconductor laser (SL). We describe a straightforward calibration...... procedure for the sFPI-LDV and investigate the effect of different degrees of laser frequency noise between the FL and the SL on the velocimeter’s performance...

  11. Modifying a Rodenstock scanning laser ophthalmoscope for imaging densitometry.

    Science.gov (United States)

    Tornow, R P; Beuel, S; Zrenner, E

    1997-08-01

    The necessary modifications and technical requirements are described for using a commercially available scanning laser ophthalmoscope (Rodenstock Model 101 SLO) as an imaging densitometer to assess human photopigment distribution. The main requirements are a linear detector amplifier, fast shutters for the laser beams, and a trigger unit. Images must be compensated for varying laser intensity. Both rod and cone photopigments are measured with the 514-nm argon laser of the SLO. Discrimination is possible owing to the different spatial distribution. The cone pigment density peaks in the foveal center (D = 0.40) with a steep decrease with increasing eccentricity E (full width at half-maximum, 2.5 degrees ). Rod photopigment increases with increasing eccentricity (D = 0.23 for E = 11 degrees ). These values are in agreement with previous reported results obtained with scanning laser ophthalmoscopes specially designed for retinal densitometry and high stability.

  12. 3D Laser Scanning in Technology Education.

    Science.gov (United States)

    Flowers, Jim

    2000-01-01

    A three-dimensional laser scanner can be used as a tool for design and problem solving in technology education. A hands-on experience can enhance learning by captivating students' interest and empowering them with creative tools. (Author/JOW)

  13. Aspects of Radar Polarimetry

    OpenAIRE

    LÜNEBURG, Ernst

    2002-01-01

    This contribution is a tutorial introduction to the phenomenological theory of radar polarimetry for the coherent scatter case emphasizing monostatic backscattering and forward scattering (transmission). Characteristic similarities and differences between radar polarimetry and optical polarimetry and the role of linear and antilinear operators (time-reversal) are pointed out and typical polarimetric invariants are identified.

  14. BENCHMARKING MOBILE LASER SCANNING SYSTEMS USING A PERMANENT TEST FIELD

    Directory of Open Access Journals (Sweden)

    H. Kaartinen

    2012-07-01

    Full Text Available The objective of the study was to benchmark the geometric accuracy of mobile laser scanning (MLS systems using a permanent test field under good coverage of GNSS. Mobile laser scanning, also called mobile terrestrial laser scanning, is currently a rapidly developing area in laser scanning where laser scanners, GNSS and IMU are mounted onboard a moving vehicle. MLS can be considered to fill the gap between airborne and terrestrial laser scanning. Data provided by MLS systems can be characterized with the following technical parameters: a point density in the range of 100-1000 points per m2 at 10 m distance, b distance measurement accuracy of 2-5 cm, and c operational scanning range from 1 to 100 m. Several commercial, including e.g. Riegl, Optech and others, and some research mobile laser scanning systems surveyed the test field using predefined driving speed and directions. The acquired georeferenced point clouds were delivered for analyzing. The geometric accuracy of the point clouds was determined using the reference targets that could be identified and measured from the point cloud. Results show that in good GNSS conditions most systems can reach an accuracy of 2 cm both in plane and elevation. The accuracy of a low cost system, the price of which is less than tenth of the other systems, seems to be within a few centimetres at least in ground elevation determination. Inaccuracies in the relative orientation of the instruments lead to systematic errors and when several scanners are used, in multiple reproductions of the objects. Mobile laser scanning systems can collect high density point cloud data with high accuracy. A permanent test field suits well for verifying and comparing the performance of different mobile laser scanning systems. The accuracy of the relative orientation between the mapping instruments needs more attention. For example, if the object is seen double in the point cloud due to imperfect boresight calibration between two

  15. HOVE-Wedge-Filtering of Geomorphologic Terrestrial Laser Scan Data

    Directory of Open Access Journals (Sweden)

    Helmut Panholzer

    2018-02-01

    Full Text Available Terrestrial laser scanning has become an important surveying technique in many fields such as natural hazard assessment. To analyse earth surface processes, it is useful to generate a digital terrain model originated from laser scan point cloud data. To determine the terrain surface as precisely as possible, it is often necessary to filter out points that do not represent the terrain surface. Examples are vegetation, vehicles, and animals. In mountainous terrain with a small-structured topography, filtering is very difficult. Here, automatic filtering solutions usually designed for airborne laser scan data often lead to unsatisfactory results. In this work, we further develop an existing approach for automated filtering of terrestrial laser scan data, which is based on the assumption that no other surface point can be located in the area above a direct line of sight between scanner and another measured point. By taking into account several environmental variables and a repetitive calculation method, the modified method leads to significantly better results. The root-mean-square-error (RSME for the same test measurement area could be reduced from 5.284 to 1.610. In addition, a new approach for filtering and interpolation of terrestrial laser scanning data is presented using a grid with horizontal and vertical angular data and the measurement length.

  16. In situ laser processing in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Nicholas A.; Magel, Gregory A.; Hartfield, Cheryl D.; Moore, Thomas M.; Fowlkes, Jason D.; Rack, Philip D. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States) and Omniprobe, Inc., an Oxford Instruments Company, 10410 Miller Rd., Dallas, Texas 75238 (United States); Omniprobe, Inc., an Oxford Instruments Company, 10410 Miller Rd., Dallas, Texas 75238 (United States); Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States) and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2012-07-15

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {mu}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  17. 2. Interferometry and polarimetry. 2.3. Polarimetry on JT-60U

    International Nuclear Information System (INIS)

    Kawano, Yasunori

    2000-01-01

    In order to establish an electron density measurement method with high reliability and stability for magnetic-confinement fusion devices, studies on infrared polarimetry have been carried out in JT-60U. Electron density measurement based on tangential Faraday rotation has been verified using a CO 2 laser polarimeter developed for JT-60U. In this article, basic ideas of studies, results from polarimetry experiments, and suggestions for future devices are presented. (author)

  18. Precision electron polarimetry

    International Nuclear Information System (INIS)

    Chudakov, E.

    2013-01-01

    A new generation of precise Parity-Violating experiments will require a sub-percent accuracy of electron beam polarimetry. Compton polarimetry can provide such accuracy at high energies, but at a few hundred MeV the small analyzing power limits the sensitivity. Mo/ller polarimetry provides a high analyzing power independent on the beam energy, but is limited by the properties of the polarized targets commonly used. Options for precision polarimetry at 300 MeV will be discussed, in particular a proposal to use ultra-cold atomic hydrogen traps to provide a 100%-polarized electron target for Mo/ller polarimetry

  19. Scanning Laser Infrared Molecular Spectrometer (SLIMS)

    Science.gov (United States)

    Scott, David C.; Rickey, Kelly; Ksendzov, Alexander; George, Warren P.; Aljabri, Abdullah S.; Steinkraus, Joel M.

    2012-01-01

    This prototype innovation is a novel design that achieves very long, effective laser path lengths that are able to yield ppb (parts per billion) and sub-ppb measurements of trace gases. SLIMS can also accommodate multiple laser channels covering a wide range of wavelengths, resulting in detection of more chemicals of interest. The mechanical design of the mirror cell allows for the large effective path length within a small footprint. The same design provides a robust structure that lends itself to being immune to some of the alignment challenges that similar cells face. By taking a hollow cylinder and by cutting an elliptically or spherically curved surface into its inner wall, the basic geometry of a reflecting ring is created. If the curved, inner surface is diamond-turned and highly polished, a surface that is very highly reflective can be formed. The surface finish can be further improved by adding a thin chrome or gold film over the surface. This creates a high-quality, curved, mirrored surface. A laser beam, which can be injected from a small bore hole in the wall of the cylinder, will be able to make many low-loss bounces around the ring, creating a large optical path length. The reflecting ring operates on the same principle as the Herriott cell. The difference exists in the mirror that doesn't have to be optically aligned, and which has a relatively large, internal surface area that lends itself to either open air or evacuated spectroscopic measurements. This solid, spherical ring mirror removes the possibility of mirror misalignment caused by thermal expansion or vibrations, because there is only a single, solid reflecting surface. Benefits of the reflecting ring come into play when size constraints reduce the size of the system, especially for space missions in which mass is at a premium.

  20. Bus bays inventory using a terrestrial laser scanning system

    Directory of Open Access Journals (Sweden)

    Bobkowska Katarzyna

    2017-01-01

    Full Text Available This article presents the use of laser scanning technology for the assessment of bus bay geo-location. Ground laser scanning is an effective tool for collecting three-dimensional data. Moreover, the analysis of a point cloud dataset can be a source of a lot of information. The authors have outlined an innovative use of data collection and analysis using the TLS regarding information on the flatness of bus bays. The results were finalized in the form of colour three-dimensional maps of deviations and pavement type.

  1. Using a laser scanning camera for reactor inspection

    International Nuclear Information System (INIS)

    Armour, I.A.; Adrain, R.S.; Klewe, R.C.

    1984-01-01

    Inspection of nuclear reactors is normally carried out using TV or film cameras. There are, however, several areas where these cameras show considerable shortcomings. To overcome these difficulties, laser scanning cameras have been developed. This type of camera can be used for general visual inspection as well as the provision of high resolution video images with high ratio on and off-axis zoom capability. In this paper, we outline the construction and operation of a laser scanning camera and give examples of how it has been used in various power stations, and indicate future potential developments. (author)

  2. Fluence scan: an unexplored property of a laser beam

    International Nuclear Information System (INIS)

    Chalupsky, Jaromir; Hajkova, Vera; Burian, Tomas; Juha, Libor; Polcar, Tomas; Gaudin, Jerome; Nagasono, Mitsuru; Yabashi, Makina; Sobierajski, Ryszard; Krzywinski, Jacek

    2013-01-01

    We present an extended theoretical background of so-called fluence scan (f-scan or F-scan) method, which is frequently being used for offline characterization of focused short-wavelength (EUV, soft X-ray, and hard X-ray) laser beams [J. Chalupsky et al., Opt. Express 18, 27836 (2010)]. The method exploits ablative imprints in various solids to visualize iso-fluence beam contours at different fluence and/or clip levels. An f-scan curve (clip level as a function of the corresponding iso-fluence contour area) can be generated for a general non-Gaussian beam. As shown in this paper, fluence scan encompasses important information about energy distribution within the beam profile, which may play an essential role in laser-matter interaction research employing intense non-ideal beams. Here we for the first time discuss fundamental properties of the f-scan function and its inverse counterpart (if-scan). Furthermore, we extensively elucidate how it is related to the effective beam area, energy distribution, and to the so called Liu's dependence [J.M. Liu, Opt. Lett. 7, 196 (1982)]. A new method of the effective area evaluation based on weighted inverse f-scan fit is introduced and applied to real data obtained at the SCSS (SPring-8 Compact SASE Source) facility. (authors)

  3. A high-finesse Fabry–Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

    International Nuclear Information System (INIS)

    Rakhman, A.; Hafez, M.; Nanda, S.; Benmokhtar, F.; Camsonne, A.; Cates, G.D.; Dalton, M.M.; Franklin, G.B.; Friend, M.; Michaels, R.W.; Nelyubin, V.; Parno, D.S.; Paschke, K.D.; Quinn, B.P.

    2016-01-01

    A high-finesse Fabry–Perot cavity with a frequency-doubled continuous wave green laser (532 nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064 nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO_3 crystal. The maximum achieved green power at 5 W infrared pump power is 1.74 W with a total conversion efficiency of 34.8%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7 kW with a corresponding enhancement of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0% precision in polarization measurements of an electron beam with energy and current of 1.06 GeV and 50 μA.

  4. A high-finesse Fabry–Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Rakhman, A., E-mail: rahim@ornl.gov [Syracuse University, Department of Physics, Syracuse, NY 13244 (United States); Research Accelerator Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Hafez, M. [Old Dominion University, Applied Research Center, Norfolk, VA 23529 (United States); Nanda, S. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Benmokhtar, F. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); Duquesne University, Pittsburgh, PA 15282 (United States); Camsonne, A. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Cates, G.D. [University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Dalton, M.M. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Franklin, G.B. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); Friend, M. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Michaels, R.W. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Nelyubin, V. [University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Parno, D.S. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); University of Washington, Center for Experimental Nuclear Physics and Astrophysics and Department of Physics, Seattle, WA 98195 (United States); Paschke, K.D. [University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Quinn, B.P. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); and others

    2016-06-21

    A high-finesse Fabry–Perot cavity with a frequency-doubled continuous wave green laser (532 nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064 nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO{sub 3} crystal. The maximum achieved green power at 5 W infrared pump power is 1.74 W with a total conversion efficiency of 34.8%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7 kW with a corresponding enhancement of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0% precision in polarization measurements of an electron beam with energy and current of 1.06 GeV and 50 μA.

  5. Optomechatronics Design and Control for Confocal Laser Scanning Microscopy

    NARCIS (Netherlands)

    Yoo, H.W.

    2015-01-01

    Confocal laser scanning microscopy (CLSM) is considered as one of the major advancements in microscopy in the last century and is widely accepted as a 3D fluorescence imaging tool for biological studies. For the emerging biological questions CLSM requires fast imaging to detect rapid biological

  6. USE OF LASER SCANNING FOR CULTURAL HERITAGE DOCUMENTATION

    Directory of Open Access Journals (Sweden)

    Gulhan BENLI

    2013-01-01

    Full Text Available In terms of raising an awareness of the historical, national and cultural properties in our country and ensuring a transfer of information to posterity, it is of vital importance to take inventory of the cultural and natural real properties located in protected sites. Many fields, such as medical science, construction, ground engineering, geodetic engineering, and architecture, make use of the present-day laser scanning technology. Even if contemporary and current scientific methods are used for the inventory and documentation studies related to cultural and natural real properties in the PROTECTED SITES in the field of architecture; acquiring data of the entirety of a protected site using these methods is a time consuming process. Among the scientific methods applied, laser scanning technology has the utmost importance in the latest years. The laser scanning devices for the detection of cultural, natural and historical properties in archeological, historical, urban or mixed protected sites in Turkey, eliminate challenges such as the enormity of sites, the difficulty of working in the sites, intense work hours, and the necessity of having a thorough knowledge of the site. In the scope of this study, the usage, application, facilities, advantages and attainments of geodetic laser scanning systems in conducting surveys on facade, street or avenue silhouettes in the protected sites, where historical buildings within field of architecture are widespread, will be examined.

  7. Data acquisition considerations for Terrestrial Laser Scanning of forest plots

    NARCIS (Netherlands)

    Wilkes, Phil; Lau Sarmiento, Alvaro; Disney, Mathias; Calders, Kim; Burt, Andrew; Gonzalez De Tanago Meñaca, J.; Bartholomeus, Harm; Brede, Benjamin; Herold, Martin

    2017-01-01

    The poor constraint of forest Above Ground Biomass (AGB) is responsible, in part, for large uncertainties in modelling future climate scenarios. Terrestrial Laser Scanning (TLS) can be used to derive unbiased and non-destructive estimates of tree structure and volume and can, therefore, be used to

  8. Accuracy assessment of airborne laser scanning strips using planar features

    NARCIS (Netherlands)

    Soudarissanane, S.S.; Van der Sande, C.J.; Khoshelham, K.

    2010-01-01

    Airborne Laser Scanning (ALS) is widely used in many applications for its high measurement accuracy, fast acquisition capability, and large spatial coverage. Accuracy assessment of the ALS data usually relies on comparing corresponding tie elements, often points or lines, in the overlapping strips.

  9. Single scan vector prediction in selective laser melting

    NARCIS (Netherlands)

    Wits, Wessel Willems; Bruins, R.; Terpstra, L.; Huls, R.A.; Geijselaers, Hubertus J.M.

    2015-01-01

    In selective laser melting (SLM) products are built by melting layers of metal powder successively. Optimal process parameters are usually obtained by scanning single vectors and subsequently determining which settings lead to a good compromise between product density and build speed. This paper

  10. Volumetry of human taste buds using laser scanning microscopy.

    Science.gov (United States)

    Just, T; Srur, E; Stachs, O; Pau, H W

    2009-10-01

    In vivo laser scanning confocal microscopy is a relatively new, non-invasive method for assessment of oral cavity epithelia. The penetration depth of approximately 200-400 microm allows visualisation of fungiform papillae and their taste buds. This paper describes the technique of in vivo volumetry of human taste buds. Confocal laser scanning microscopy used a diode laser at 670 nm for illumination. Digital laser scanning confocal microscopy equipment consisted of the Heidelberg Retina Tomograph HRTII and the Rostock Cornea Module. Volume scans of fungiform papillae were used for three-dimensional reconstruction of the taste bud. This technique supplied information on taste bud structure and enabled measurement and calculation of taste bud volume. Volumetric data from a 23-year-old man over a nine-day period showed only a small deviation in values. After three to four weeks, phenomenological changes in taste bud structures were found (i.e. a significant increase in volume, followed by disappearance of the taste bud and appearance of a new taste bud). The data obtained indicate the potential application of this non-invasive imaging modality: to evaluate variation of taste bud volume in human fungiform papillae with ageing; to study the effects of chorda tympani nerve transection on taste bud volume; and to demonstrate recovery of taste buds in patients with a severed chorda tympani nerve who show recovery of gustatory sensibility after surgery.

  11. COMPARISON OF RETINAL PATHOLOGY VISUALIZATION IN MULTISPECTRAL SCANNING LASER IMAGING.

    Science.gov (United States)

    Meshi, Amit; Lin, Tiezhu; Dans, Kunny; Chen, Kevin C; Amador, Manuel; Hasenstab, Kyle; Muftuoglu, Ilkay Kilic; Nudleman, Eric; Chao, Daniel; Bartsch, Dirk-Uwe; Freeman, William R

    2018-03-16

    To compare retinal pathology visualization in multispectral scanning laser ophthalmoscope imaging between the Spectralis and Optos devices. This retrospective cross-sectional study included 42 eyes from 30 patients with age-related macular degeneration (19 eyes), diabetic retinopathy (10 eyes), and epiretinal membrane (13 eyes). All patients underwent retinal imaging with a color fundus camera (broad-spectrum white light), the Spectralis HRA-2 system (3-color monochromatic lasers), and the Optos P200 system (2-color monochromatic lasers). The Optos image was cropped to a similar size as the Spectralis image. Seven masked graders marked retinal pathologies in each image within a 5 × 5 grid that included the macula. The average area with detected retinal pathology in all eyes was larger in the Spectralis images compared with Optos images (32.4% larger, P < 0.0001), mainly because of better visualization of epiretinal membrane and retinal hemorrhage. The average detection rate of age-related macular degeneration and diabetic retinopathy pathologies was similar across the three modalities, whereas epiretinal membrane detection rate was significantly higher in the Spectralis images. Spectralis tricolor multispectral scanning laser ophthalmoscope imaging had higher rate of pathology detection primarily because of better epiretinal membrane and retinal hemorrhage visualization compared with Optos bicolor multispectral scanning laser ophthalmoscope imaging.

  12. Preliminary testing of the Scanning Laser Environmental Airborne Fluorosensor

    International Nuclear Information System (INIS)

    Brown, C.E.; Marois, R.; Fingas, M.F.; Mullin, J.V.

    2000-01-01

    The installation and testing program of the Scanning Laser Environmental Airborne Fluorosensor (SLEAF) on Environment Canada's DC-3 aircraft was described and the capabilities of the new system were presented. SLEAF is a new generation of laser fluorosensor designed to provide prompt reliable detection and mapping of oil pollution in different marine and terrestrial environments. It consists of a high-power excimer laser, high-resolution range-gated intensified diode-array spectrometer, and a pair of variable speed and angular displacement scanning mirrors. SLEAF is capable of detecting narrow bands of oil that can pile up along the high tide lines of beaches and shorelines, including those that contain ice and snow. It also has the added benefit of providing real-time detection. SLEAF will be declared operational for emergency response personnel when the initial test flight program will be completed in the near future. 9 refs., 2 figs

  13. Fluence scan: an unexplored property of a laser beam

    Czech Academy of Sciences Publication Activity Database

    Chalupský, Jaromír; Burian, Tomáš; Hájková, Věra; Juha, Libor; Polcar, T.; Gaudin, J.; Nagasono, M.; Sobierajski, R.; Yabashi, M.; Krzywinski, J.

    2013-01-01

    Roč. 21, č. 22 (2013), s. 26363-26375 ISSN 1094-4087 R&D Projects: GA ČR(CZ) GAP108/11/1312; GA ČR GA13-28721S; GA MŠk(CZ) LG13029; GA ČR GAP208/10/2302; GA ČR GAP205/11/0571; GA MŠk EE2.3.30.0057 Grant - others:AVČR(CZ) M100101221; OP VK 4 POSTDOK(XE) CZ.1.07/2.3.00/30.0057 Institutional support: RVO:68378271 Keywords : free-electron lasers (FELs) * UV * EUV * x-ray lasers * laser beam characterization * F-scan Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.525, year: 2013

  14. Polarimetry of random fields

    Science.gov (United States)

    Ellis, Jeremy

    On temporal, spatial and spectral scales which are small enough, all fields are fully polarized. In the optical regime, however, instantaneous fields can rarely be examined, and, instead, only average quantities are accessible. The study of polarimetry is concerned with both the description of electromagnetic fields and the characterization of media a field has interacted with. The polarimetric information is conventionally presented in terms of second order field correlations which are averaged over the ensemble of field realizations. Motivated by the deficiencies of classical polarimetry in dealing with specific practical situations, this dissertation expands the traditional polarimetric approaches to include higher order field correlations and the description of fields fluctuating in three dimensions. In relation to characterization of depolarizing media, a number of fourth-order correlations are introduced in this dissertation. Measurements of full polarization distributions, and the subsequent evaluation of Stokes vector element correlations and Complex Degree of Mutual Polarization demonstrate the use of these quantities for material discrimination and characterization. Recent advancements in detection capabilities allow access to fields near their sources and close to material boundaries, where a unique direction of propagation is not evident. Similarly, there exist classical situations such as overlapping beams, focusing, or diffusive scattering in which there is no unique transverse direction. In this dissertation, the correlation matrix formalism is expanded to describe three dimensional electromagnetic fields, providing a definition for the degree of polarization of such a field. It is also shown that, because of the dimensionality of the problem, a second parameter is necessary to fully describe the polarimetric properties of three dimensional fields. Measurements of second-order correlations of a three dimensional field are demonstrated, allowing the

  15. Laser Ultrasound Spectroscopy Scanning for 3D Printed Parts

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, Guendalyn Kendra [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-04

    One of the challenges of additive manufacturing is quality control due to the possibility of unseen flaws in the final product. The current methods of inspection are lacking in detail, too slow for practical use, or unable to validate internal structure. This report examines the use of laser ultrasound spectroscopy in layer by layer scans of 3D printed parts as they are created. The result is fast and detailed quality control. An additional advantage of this method is the ability to cancel a print as soon as a defect is detected, therefore saving materials and time. This technique, though simple in concept, has been a challenge to implement. I discuss tweaking the 3D printer configuration, and finding the optimal settings for laser scanning small parts made of ABS plastic, as well as the limits of how small of a detail the laser can detect. These settings include the frequency of the ultrasonic transducer, the speed of the laser, and the distance from the laser to the part.

  16. Laser scanning of a recirculation zone on the Bolund escarpment

    DEFF Research Database (Denmark)

    Mann, Jakob; Angelou, Nikolas; Sjöholm, Mikael

    2012-01-01

    Rapid variations in the height of the recirculation zone are measured with a scanning wind lidar over a small escarpment on the Bolund Peninsula. The lidar is essentially a continuous-wave laser Doppler anemometer with the capability of rapidly changing the focus distance and the beam direction....... The instrument measures the line-ofsight velocity 390 times per second and scans ten wind profiles from the ground up to seven meters per second. The results will be used to test computational fluid dynamics models for flow over terrain, and has relevance for wind energy. The development of multiple lidar...

  17. Laser scanning of a recirculation zone on the Bolund escarpment

    DEFF Research Database (Denmark)

    Mann, Jakob; Angelou, Nikolas; Sjöholm, Mikael

    2014-01-01

    Rapid variations in the height of the recirculation zone are measured with a scanning wind lidar over a small escarpment on the Bolund Peninsula. The lidar is essentially a continuous-wave laser Doppler anemometer with the capability of rapidly changing the focus distance and the beam direction....... The instrument measures the line-of-sight velocity 390 times per second and scans ten wind profiles from the ground up to seven meters per second. We observe a sharp interface between slow and fast moving fluid after the escarpment, and the interface is moving rapidly up and down. This implies that the position...

  18. Visual Evoked Potential and Magnetic Resonance Imaging are More Effective Markers of Multiple Sclerosis Progression than Laser Polarimetry with Variable Corneal Compensation.

    Science.gov (United States)

    Kantorová, Ema; Ziak, Peter; Kurča, Egon; Koyšová, Mária; Hladká, Mária; Zeleňák, Kamil; Michalik, Jozef

    2014-01-01

    The aim of our study was to assess the role of laser polarimetry and visual evoked potentials (VEP) as potential biomarkers of disease progression in multiple sclerosis (MS). A total of 41 patients with MS (82 eyes) and 22 age-related healthy volunteers (44 eyes) completed the study. MS patients were divided into two groups, one (ON) with a history of optic neuritis (17 patients, 34 eyes) and another group (NON) without it (24 patients, 48 eyes). The MS patients and controls underwent laser polarimetry (GDx) examination of the retinal nerve fiber layer (RNFL). In the MS group, we also examined: Kurtzke "expanded disability status scale" (EDSS), the duration of the disorder, VEP - latency and amplitude, and conventional brain magnetic resonance imaging (MRI). Our results were statistically analyzed using ANOVA, Mann-Whitney, and Spearman correlation analyses. In the MS group, brain atrophy and new T2 brain lesions in MRI correlated with both VEP latencies and amplitudes. Separate comparisons revealed VEP latency testing to be less sensitive in ON than in NON-patients. In ON patients, VEP amplitudes correlated mildly with brain atrophy (r = -0.15) and strongly with brain new MRI lesions (r = -0.8). In NON-patients, highly significant correlation of new MRI brain lesions with VEP latencies (r = 0.63, r = 0.6) and amplitudes (r = -0.3, r = -4.2) was found. EDSS also correlated with brain atrophy in this group (r = 0.5). Our study did not find a correlation of GDx measures with MRI tests. The GDx method was not able to detect whole brain demyelinization and the degeneration process, but was only able to reveal the involvement of optic nerves in ON and NON-patients. In our study, we found that both methods (VEP and GDx) can be used for the detection of optic nerve damage, but VEP was found to be superior in evaluating whole brain demyelinization and axonal degeneration. Both VEP and MRI, but not GDx, have an important role in monitoring

  19. Visual evoked potential and magnetic resonance imaging are more effective markers of multiple sclerosis progression than laser polarimetry with variable corneal compensation

    Directory of Open Access Journals (Sweden)

    Ema eKantorová

    2014-01-01

    Full Text Available Backround: The aim of our study was to assess the role of laser polarimetry and visual evoked potentials as potential biomarkers of disease progression in multiple sclerosis (MS. Participants: A total of 41 patients with MS (82 eyes and 22 age-related healthy volunteers (44 eyes completed the study. MS patients were divided into two groups, one (ON with a history of optic neuritis (17 patients, 34 eyes and another group (NON without it (24 patients, 48 eyes. The MS patients and controls underwent laser polarimetry (GDx examination of the retinal nerve fibre layer (RNFL. In the MS group we also examined: Kurtzke Expanded disability status scale (EDSS, the duration of the disorder, visual evoked potentials (VEP – latency and amplitude – and conventional brain MRI. Results: In the MS group, brain atrophy and new T2 brain lesions in MRI correlated with both VEP latencies and amplitudes. Separate comparisons revealed VEP latency testing to be less sensitive in ON than in NON patients. In ON patients, VEP amplitudes correlated mildly with brain atrophy (r =-0.15 and strongly with brain new MRI lesions (r = -0.8. In NON patients, highly significant correlation of new MRI brain lesions with VEP latencies (r = 0.63, r = 0.6, and amplitudes ( r = -0.3, r = -4.2 was found. EDSS also correlated with brain atrophy in this group (r = 0.5. Our study did not find a correlation of GDx measures with MRI tests. The GDx method was not able to detect whole brain demyelinisation and the degeneration process, but was only able to reveal the involvement of optic nerves in ON and NON patients.Conclusions: In our study, we found that both methods (VEP and GDx can be used for detection of optic nerve damage, but VEP was found to be superior in evaluating whole brain demyelinisation and axonal degeneration. Both VEP and MRI, but not GDx, have an important role in monitoring disease progression in MS patients, independent of the ON history.

  20. A New Multichannel Spectral Imaging Laser Scanning Confocal Microscope

    Directory of Open Access Journals (Sweden)

    Yunhai Zhang

    2013-01-01

    Full Text Available We have developed a new multichannel spectral imaging laser scanning confocal microscope for effective detection of multiple fluorescent labeling in the research of biological tissues. In this paper, the design and key technologies of the system are introduced. Representative results on confocal imaging, 3-dimensional sectioning imaging, and spectral imaging are demonstrated. The results indicated that the system is applicable to multiple fluorescent labeling in biological experiments.

  1. Modeling 3D Objects for Navigation Purposes Using Laser Scanning

    Directory of Open Access Journals (Sweden)

    Cezary Specht

    2016-07-01

    Full Text Available The paper discusses the creation of 3d models and their applications in navigation. It contains a review of available methods and geometric data sources, focusing mostly on terrestrial laser scanning. It presents detailed description, from field survey to numerical elaboration, how to construct accurate model of a typical few storey building as a hypothetical reference in complex building navigation. Hence, the paper presents fields where 3d models are being used and their potential new applications.

  2. Quality Assurance By Laser Scanning And Imaging Techniques

    Science.gov (United States)

    SchmalfuB, Harald J.; Schinner, Karl Ludwig

    1989-03-01

    Laser scanning systems are well established in the world of fast industrial in-process quality inspection systems. The materials inspected by laser scanning systems are e.g. "endless" sheets of steel, paper, textile, film or foils. The web width varies from 50 mm up to 5000 mm or more. The web speed depends strongly on the production process and can reach several hundred meters per minute. The continuous data flow in one of different channels of the optical receiving system exceeds ten Megapixels/sec. Therefore it is clear that the electronic evaluation system has to process these data streams in real time and no image storage is possible. But sometimes (e.g. first installation of the system, change of the defect classification) it would be very helpful to have the possibility for a visual look on the original, i.e. not processed sensor data. At first we show the principle set up of a standard laser scanning system. Then we will introduce a large image memory especially designed for the needs of high-speed inspection sensors. This image memory co-operates with the standard on-line evaluation electronics and provides therefore an easy comparison between processed and non-processed data. We will discuss the basic system structure and we will show the first industrial results.

  3. Calibration technology in application of robot-laser scanning system

    Science.gov (United States)

    Ren, YongJie; Yin, ShiBin; Zhu, JiGui

    2012-11-01

    A system composed of laser sensor and 6-DOF industrial robot is proposed to obtain complete three-dimensional (3-D) information of the object surface. Suitable for the different combining ways of laser sensor and robot, a new method to calibrate the position and pose between sensor and robot is presented. By using a standard sphere with known radius as a reference tool, the rotation and translation matrices between the laser sensor and robot are computed, respectively in two steps, so that many unstable factors introduced in conventional optimization methods can be avoided. The experimental results show that the accuracy of the proposed calibration method can be achieved up to 0.062 mm. The calibration method is also implemented into the automated robot scanning system to reconstruct a car door panel.

  4. Improving Completeness of Geometric Models from Terrestrial Laser Scanning Data

    Directory of Open Access Journals (Sweden)

    Clemens Nothegger

    2011-12-01

    Full Text Available The application of terrestrial laser scanning for the documentation of cultural heritage assets is becoming increasingly common. While the point cloud by itself is sufficient for satisfying many documentation needs, it is often desirable to use this data for applications other than documentation. For these purposes a triangulated model is usually required. The generation of topologically correct triangulated models from terrestrial laser scans, however, still requires much interactive editing. This is especially true when reconstructing models from medium range panoramic scanners and many scan positions. Because of residual errors in the instrument calibration and the limited spatial resolution due to the laser footprint, the point clouds from different scan positions never match perfectly. Under these circumstances many of the software packages commonly used for generating triangulated models produce models which have topological errors such as surface intersecting triangles, holes or triangles which violate the manifold property. We present an algorithm which significantly reduces the number of topological errors in the models from such data. The algorithm is a modification of the Poisson surface reconstruction algorithm. Poisson surfaces are resilient to noise in the data and the algorithm always produces a closed manifold surface. Our modified algorithm partitions the data into tiles and can thus be easily parallelized. Furthermore, it avoids introducing topological errors in occluded areas, albeit at the cost of producing models which are no longer guaranteed to be closed. The algorithm is applied to scan data of sculptures of the UNESCO World Heritage Site Schönbrunn Palace and data of a petrified oyster reef in Stetten, Austria. The results of the method’s application are discussed and compared with those of alternative methods.

  5. Categorisation of full waveform data provided by laser scanning devices

    Science.gov (United States)

    Ullrich, Andreas; Pfennigbauer, Martin

    2011-11-01

    In 2004, a laser scanner device for commercial airborne laser scanning applications, the RIEGL LMS-Q560, was introduced to the market, making use of a radical alternative approach to the traditional analogue signal detection and processing schemes found in LIDAR instruments so far: digitizing the echo signals received by the instrument for every laser pulse and analysing these echo signals off-line in a so-called full waveform analysis in order to retrieve almost all information contained in the echo signal using transparent algorithms adaptable to specific applications. In the field of laser scanning the somewhat unspecific term "full waveform data" has since been established. We attempt a categorisation of the different types of the full waveform data found in the market. We discuss the challenges in echo digitization and waveform analysis from an instrument designer's point of view and we will address the benefits to be gained by using this technique, especially with respect to the so-called multi-target capability of pulsed time-of-flight LIDAR instruments.

  6. Stellar photometry and polarimetry

    International Nuclear Information System (INIS)

    Golay, M.; Serkowski, K.

    1976-01-01

    A critical review of progress made in stellar photometry and polarimetry over the period 1973-1975 is presented. Reports of photometric measurements from various observatories throughout the world are summarized. The summary of work on stellar polarimetry lists the review papers, the catalogues and lists of standard stars, and descriptions of new observing techniques. (B.R.H.)

  7. Measurement Axis Searching Model for Terrestrial Laser Scans Registration

    Directory of Open Access Journals (Sweden)

    Shaoxing Hu

    2016-01-01

    Full Text Available Nowadays, terrestrial Lidar scans can cover rather a large area; the point densities are strongly varied because of the line-of-sight measurement principle in potential overlaps with scans taken from different viewpoints. Most of the traditional methods focus on registration algorithm and ignore searching model. Sometimes the traditional methods are directly used to align two point clouds; a large critically unsolved problem of the large biases will be created in areas distant from the overlaps while the local overlaps are often aligned well. So a novel measurement axis searching model (MASM has been proposed in this paper. The method includes four steps: (1 the principal axis fitting, (2 the measurement axis generation, (3 low-high-precision search, and (4 result generation. The principal axis gives an orientation to the point cloud; the search scope is limited by the measurement axis. The point cloud orientation can be adjusted gradually until the achievement of the global optimum using low- and high-precision search. We perform some experiments with simulated point clouds and real terrestrial laser scans. The results of simulated point clouds have shown the processing steps of our method, and the results of real terrestrial laser scans have shown the sensitivity of the approach with respect to the indoor and outdoor scenes.

  8. How the confocal laser scanning microscope entered biological research.

    Science.gov (United States)

    Amos, W B; White, J G

    2003-09-01

    A history of the early development of the confocal laser scanning microscope in the MRC Laboratory of Molecular Biology in Cambridge is presented. The rapid uptake of this technology is explained by the wide use of fluorescence in the 80s. The key innovations were the scanning of the light beam over the specimen rather than vice-versa and a high magnification at the level of the detector, allowing the use of a macroscopic iris. These were followed by an achromatic all-reflective relay system, a non-confocal transmission detector and novel software for control and basic image processing. This design was commercialized successfully and has been produced and developed over 17 years, surviving challenges from alternative technologies, including solid-state scanning systems. Lessons are pointed out from the unusual nature of the original funding and research environment. Attention is drawn to the slow adoption of the instrument in diagnostic medicine, despite promising applications.

  9. Laser cutting of irregular shape object based on stereo vision laser galvanometric scanning system

    Science.gov (United States)

    Qi, Li; Zhang, Yixin; Wang, Shun; Tang, Zhiqiang; Yang, Huan; Zhang, Xuping

    2015-05-01

    Irregular shape objects with different 3-dimensional (3D) appearances are difficult to be shaped into customized uniform pattern by current laser machining approaches. A laser galvanometric scanning system (LGS) could be a potential candidate since it can easily achieve path-adjustable laser shaping. However, without knowing the actual 3D topography of the object, the processing result may still suffer from 3D shape distortion. It is desirable to have a versatile auxiliary tool that is capable of generating 3D-adjusted laser processing path by measuring the 3D geometry of those irregular shape objects. This paper proposed the stereo vision laser galvanometric scanning system (SLGS), which takes the advantages of both the stereo vision solution and conventional LGS system. The 3D geometry of the object obtained by the stereo cameras is used to guide the scanning galvanometers for 3D-shape-adjusted laser processing. In order to achieve precise visual-servoed laser fabrication, these two independent components are integrated through a system calibration method using plastic thin film target. The flexibility of SLGS has been experimentally demonstrated by cutting duck feathers for badminton shuttle manufacture.

  10. Laser sintering of metal powders on top of sintered layers under multiple-line laser scanning

    International Nuclear Information System (INIS)

    Xiao Bin; Zhang Yuwen

    2007-01-01

    A three-dimensional numerical model for multiple-line sintering of loose powders on top of multiple sintered layers under the irradiation of a moving Gaussian laser beam is carried out. The overlaps between vertically deposited layers and adjacent lines which strengthen bonding are taken into account. The energy equation is formulated using the temperature transforming model and solved by the finite volume method. The effects of the number of the existing sintered layers, porosity and initial temperature coupled with the optimal combination laser intensity and scanning velocity are presented. The results show that the liquid pool moves slightly towards the negative scanning direction and the shape of the liquid pool becomes shallower with higher scanning velocity. A higher laser intensity is needed to achieve the required overlaps when the number of the existing sintered layers increases. Increasing porosity or initial temperature enhances the sintering process and thus less intensity is needed for the overlap requirement

  11. Land-Based Mobile Laser Scanning Systems: a Review

    Science.gov (United States)

    Puente, I.; González-Jorge, H.; Arias, P.; Armesto, J.

    2011-09-01

    Mobile mapping has been using various photogrammetric techniques for many years. In recent years, there has been an increase in the number of mobile mapping systems using laser scanners available in the market, partially because of the improvement in GNSS/INS performance for direct georeferencing. In this article, some of the most important land-based mobile laser scanning (MLS) systems are reviewed. Firstly, the main characteristics of MLS systems vs. airborne (ALS) and terrestrial laser scanning (TLS) systems are compared. Secondly, a short overview of the mobile mapping technology is also provided so that the reader can fully grasp the complexity and operation of these devices. As we put forward in this paper, a comparison of different systems is briefly carried out regarding specifications provided by the manufacturers. Focuses on the current research are also addressed with emphasis on the practical applications of these systems. Most of them have been utilized for data collection on road infrastructures or building façades. This article shows that MLS technology is nowadays well established and proven, since the demand has grown to the point that there are several systems suppliers offering their products to satisfy this particular market.

  12. Codification of scan path parameters and development of perimeter scan strategies for 3D bowl-shaped laser forming

    Science.gov (United States)

    Tavakoli, A.; Naeini, H. Moslemi; Roohi, Amir H.; Gollo, M. Hoseinpour; Shahabad, Sh. Imani

    2018-01-01

    In the 3D laser forming process, developing an appropriate laser scan pattern for producing specimens with high quality and uniformity is critical. This study presents certain principles for developing scan paths. Seven scan path parameters are considered, including: (1) combined linear or curved path; (2) type of combined linear path; (3) order of scan sequences; (4) the position of the start point in each scan; (5) continuous or discontinuous scan path; (6) direction of scan path; and (7) angular arrangement of combined linear scan paths. Regarding these path parameters, ten combined linear scan patterns are presented. Numerical simulations show continuous hexagonal, scan pattern, scanning from outer to inner path, is the optimized. In addition, it is observed the position of the start point and the angular arrangement of scan paths is the most effective path parameters. Also, further experimentations show four sequences due to creat symmetric condition enhance the height of the bowl-shaped products and uniformity. Finally, the optimized hexagonal pattern was compared with the similar circular one. In the hexagonal scan path, distortion value and standard deviation rather to edge height of formed specimen is very low, and the edge height despite of decreasing length of scan path increases significantly compared to the circular scan path. As a result, four-sequence hexagonal scan pattern is proposed as the optimized perimeter scan path to produce bowl-shaped product.

  13. Deriving structural forest parameters using airborne laser scanning

    International Nuclear Information System (INIS)

    Morsdorf, F.

    2011-01-01

    Airborne laser scanning is a relatively young and precise technology to directly measure surface elevations. With today's high scanning rates, dense 3-D pointclouds of coordinate triplets (xyz) can be provided, in which many structural aspects of the vegetation are contained. The challenge now is to transform this data, as far as possible automatically, into manageable information relevant to the user. In this paper we present two such methods: the first extracts automatically the geometry of individual trees, with a recognition rate of over 70% and a systematic underestimation of tree height of only 0.6 metres. The second method derives a pixel map of the canopy density from the pointcloud, in which the spatial patterns of vegetation cover are represented. These patterns are relevant for habitat analysis and ecosystem studies. The values derived by this method correlate well with field measurements, giving a measure of certainty (R 2 ) of 0.8. The greatest advantage of airborne laser scanning is that it provides spatially extensive, direct measurements of vegetation structure which show none of the extrapolation errors of spot measurements. A large challenge remains in integrating these new products into the user's processing chains and workflows, be it in the realm of forestry or in that of ecosystem research. (author) [de

  14. Application of Laser Scanning for Creating Geological Documentation

    Directory of Open Access Journals (Sweden)

    Buczek Michał

    2018-01-01

    Full Text Available A geological documentation is based on the analyses obtained from boreholes, geological exposures, and geophysical methods. It consists of text and graphic documents, containing drilling sections, vertical crosssections through the deposit and various types of maps. The surveying methods (such as LIDAR can be applied in measurements of exposed rock layers, presented in appendices to the geological documentation. The laser scanning allows obtaining a complete profile of exposed surfaces in a short time and with a millimeter accuracy. The possibility of verifying the existing geological cross-section with laser scanning was tested on the example of the AGH experimental mine. The test field is built of different lithological rocks. Scans were taken from a single station, under favorable measuring conditions. The analysis of the signal intensity allowed to divide point cloud into separate geological layers. The results were compared with the geological profiles of the measured object. The same approach was applied to the data from the Vietnamese hard coal open pit mine Coc Sau. The thickness of exposed coal bed deposits and gangue layers were determined from the obtained data (point cloud in combination with the photographs. The results were compared with the geological cross-section.

  15. Scanning laser beam displays based on a 2D MEMS

    Science.gov (United States)

    Niesten, Maarten; Masood, Taha; Miller, Josh; Tauscher, Jason

    2010-05-01

    The combination of laser light sources and MEMS technology enables a range of display systems such as ultra small projectors for mobile devices, head-up displays for vehicles, wearable near-eye displays and projection systems for 3D imaging. Images are created by scanning red, green and blue lasers horizontally and vertically with a single two-dimensional MEMS. Due to the excellent beam quality of laser beams, the optical designs are efficient and compact. In addition, the laser illumination enables saturated display colors that are desirable for augmented reality applications where a virtual image is used. With this technology, the smallest projector engine for high volume manufacturing to date has been developed. This projector module has a height of 7 mm and a volume of 5 cc. The resolution of this projector is WVGA. No additional projection optics is required, resulting in an infinite focus depth. Unlike with micro-display projection displays, an increase in resolution will not lead to an increase in size or a decrease in efficiency. Therefore future projectors can be developed that combine a higher resolution in an even smaller and thinner form factor with increased efficiencies that will lead to lower power consumption.

  16. AUTOMATIC RAILWAY POWER LINE EXTRACTION USING MOBILE LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    S. Zhang

    2016-06-01

    Full Text Available Research on power line extraction technology using mobile laser point clouds has important practical significance on railway power lines patrol work. In this paper, we presents a new method for automatic extracting railway power line from MLS (Mobile Laser Scanning data. Firstly, according to the spatial structure characteristics of power-line and trajectory, the significant data is segmented piecewise. Then, use the self-adaptive space region growing method to extract power lines parallel with rails. Finally use PCA (Principal Components Analysis combine with information entropy theory method to judge a section of the power line whether is junction or not and which type of junction it belongs to. The least squares fitting algorithm is introduced to model the power line. An evaluation of the proposed method over a complicated railway point clouds acquired by a RIEGL VMX450 MLS system shows that the proposed method is promising.

  17. Resolution Enhancement of Scanning Laser Acoustic Microscope Using Transverse Wave

    International Nuclear Information System (INIS)

    Ko, D. S.; Park, J. S.; Kim, Y. H.

    1997-01-01

    We studied the resolution enhancement of a novel scanning laser acoustic microscope (SLAM) using transverse waves. Mode conversion of the ultrasonic wave takes place at the liquid-solid interface and some energy of the insonifying longitudinal waves in the water will convert to transverse wave energy within the solid specimen. The resolution of SLAM depends on the size of detecting laser spot and the wavelength of the insonifying ultrasonic waves. Science the wavelength of the transverse wave is shorter than that of the longitudinal wave, we are able to achieve the high resolution by using transverse waves. In order to operate SLAM in the transverse wave mode, we made wedge for changing the incident angle. Our experimental results with model 2140 SLAM and an aluminum specimen showed higher contrast of the SLAM image in the transverse wave mode than that in the longitudinal wave mode

  18. 2-photon laser scanning microscopy on native human cartilage

    Science.gov (United States)

    Martini, Joerg; Toensing, Katja; Dickob, Michael; Anselmetti, Dario

    2005-08-01

    Native hyaline cartilage from a human knee joint was directly investigated with laser scanning microscopy via 2-photon autofluorescence excitation with no additional staining or labelling protocols in a nondestructive and sterile manner. Using a femtosecond, near-infrared (NIR) Ti:Sa laser for 2-photon excitation and a dedicated NIR long distance objective, autofluorescence imaging and measurements of the extracellular matrix (ECM) tissue with incorporated chondrocytes were possible with a penetration depth of up to 460 μm inside the sample. Via spectral autofluorescence separation these experiments allowed the discrimination of chondrocytes from the ECM and therefore an estimate of chondrocytic cell density within the cartilage tissue to approximately 0.2-2•107cm3. Furthermore, a comparison of the relative autofluorescence signals between nonarthritic and arthritic cartilage tissue exhibited distinct differences in tissue morphology. As these morphological findings are in keeping with the macroscopic diagnosis, our measurement has the potential of being used in future diagnostic applications.

  19. Surface characterization of weathered wood using a laser scanning system

    International Nuclear Information System (INIS)

    Arnold, M.; Lemaster, R.L.; Dost, W.A.

    1992-01-01

    Most of the existing methods to assess the effect of weathering on wood surfaces have some drawbacks that limit their use to specific tasks. The amount of surface erosion is often used as a measure for the weathering action. The application of a laser scanning system to reproduce surface profiles and to measure weathering erosion was tested on various samples and was found to be a very useful and superior alternative to existing methods. Further improvements of the system used can be made by refinements of the calibration procedures and by more comprehensive profile analyses. (author)

  20. Automatic Indoor Building Reconstruction from Mobile Laser Scanning Data

    Science.gov (United States)

    Xie, L.; Wang, R.

    2017-09-01

    Indoor reconstruction from point clouds is a hot topic in photogrammetry, computer vision and computer graphics. Reconstructing indoor scene from point clouds is challenging due to complex room floorplan and line-of-sight occlusions. Most of existing methods deal with stationary terrestrial laser scanning point clouds or RGB-D point clouds. In this paper, we propose an automatic method for reconstructing indoor 3D building models from mobile laser scanning point clouds. The method includes 2D floorplan generation, 3D building modeling, door detection and room segmentation. The main idea behind our approach is to separate wall structure into two different types as the inner wall and the outer wall based on the observation of point distribution. Then we utilize a graph cut based optimization method to solve the labeling problem and generate the 2D floorplan based on the optimization result. Subsequently, we leverage an ?-shape based method to detect the doors on the 2D projected point clouds and utilize the floorplan to segment the individual room. The experiments show that this door detection method can achieve a recognition rate at 97% and the room segmentation method can attain the correct segmentation results. We also evaluate the reconstruction accuracy on the synthetic data, which indicates the accuracy of our method is comparable to the state-of-the art.

  1. Adaptive optics scanning laser ophthalmoscope imaging: technology update

    Directory of Open Access Journals (Sweden)

    Merino D

    2016-04-01

    Full Text Available David Merino, Pablo Loza-Alvarez The Institute of Photonic Sciences (ICFO, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain Abstract: Adaptive optics (AO retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it. Keywords: high-resolution, in vivo retinal imaging, AOSLO

  2. Application of terrestrial laser scanning for measuring tree crown structures

    International Nuclear Information System (INIS)

    Pretzsch, H.; Seifert, S.; Huang, P.

    2011-01-01

    This paper addresses the potential of terrestrial laser scanning (TLS) for describing and modelling of tree crown structure and dynamics. We first present a general approach for the metabolic and structural scaling of tree crowns. Out of this approach we emphasize those normalization and scaling parameters which become accessible by TLS. For example we show how the individual tree leaf area index, convex hull, and its space-filling by leaves can be extracted out of laser scan data. This contributes to a theoretical and empirical substantiation of crown structure models which were missing so far for e.g. quantification of structural and species diversity in forest stands, inventory of crown biomass, species detection by remote sensing, and understanding of self- and alien-thinning in pure and mixed stands. Up to now works on this topic delivered a rather scattered empirical knowledge mainly by single inventories of trees and stands. In contrast, we recommend to start with a model approach, and to complete existing data with repeated TLS inventories in order to come to a consistent and theoretically based model of tree crowns. (author) [de

  3. Test field for airborne laser scanning in Finland

    Science.gov (United States)

    Ahokas, E.; Kaartinen, H.; Kukko, A.; Litkey, P.

    2014-11-01

    Airborne laser scanning (ALS) is a widely spread operational measurement tool for obtaining 3D coordinates of the ground surface. There is a need for calibrating the ALS system and a test field for ALS was established at the end of 2013. The test field is situated in the city of Lahti, about 100 km to the north of Helsinki. The size of the area is approximately 3.5 km × 3.2 km. Reference data was collected with a mobile laser scanning (MLS) system assembled on a car roof. Some streets were measured both ways and most of them in one driving direction only. The MLS system of the Finnish Geodetic Institute (FGI) consists of a navigation system (NovAtel SPAN GNSS-IMU) and a laser scanner (FARO Focus3D 120). In addition to the MLS measurements more than 800 reference points were measured using a Trimble R8 VRS-GNSS system. Reference points are along the streets, on parking lots, and white pedestrian crossing line corners which can be used as reference targets. The National Land Survey of Finland has already used this test field this spring for calibrating their Leica ALS-70 scanner. Especially it was easier to determine the encoder scale factor parameter using this test field. Accuracy analysis of the MLS points showed that the point height RMSE is 2.8 cm and standard deviation is 2.6 cm. Our purpose is to measure both more MLS data and more reference points in the test field area to get a better spatial coverage. Calibration flight heights are planned to be 1000 m and 2500 m above ground level. A cross pattern, southwest-northeast and northwest-southeast, will be flown both in opposite directions.

  4. Innovation and optimization of a method of pump-probe polarimetry with pulsed laser beams in view of a precise measurement of parity violation in atomic cesium

    International Nuclear Information System (INIS)

    Chauvat, D.

    1997-10-01

    While Parity Violation (PV) experiments on highly forbidden transitions have been using detection of fluorescence signals; our experiment uses a pump-probe scheme to detect the PV signal directly on a transmitted probe beam. A pulsed laser beam of linear polarisation ε 1 excites the atoms on the 6S-7S cesium transition in a colinear electric field E || k(ex). The probe beam (k(pr) || k(ex)) of linear polarisation ε 2 tuned to the transition 7S-6P(3/2) is amplified. The small asymmetry (∼ 10 -6 ) in the gain that depends on the handedness of the tri-hedron (E, ε 1 , ε 2 ) is the manifestation of the PV effect. This is measured as an E-odd apparent rotation of the plane of polarization of the probe beam; using balanced mode polarimetry. New criteria of selection have been devised, that allow us to distinguish the true PV-signal against fake rotations due to electromagnetic interferences, geometrical effects, polarization imperfections, or stray transverse electric and magnetic fields. These selection criteria exploit the symmetry of the PV-rotation - linear dichroism - and the revolution symmetry of the experiment. Using these criteria it is not only possible to reject fake signals, but also to elucidate the underlying physical mechanisms and to measure the relevant defects of the apparatus. The present signal-to-noise ratio allows embarking in PV measurements to reach the 10% statistical accuracy. A 1% measurement still requires improvements. Two methods have been demonstrated. The first one exploits the amplification of the asymmetry at high gain - one major advantage provided by our detection method based on stimulated emission. The second method uses both a much higher incident intensity and a special dichroic component which magnifies tiny polarization rotations. (author)

  5. Pavement cracking measurements using 3D laser-scan images

    International Nuclear Information System (INIS)

    Ouyang, W; Xu, B

    2013-01-01

    Pavement condition surveying is vital for pavement maintenance programs that ensure ride quality and traffic safety. This paper first introduces an automated pavement inspection system which uses a three-dimensional (3D) camera and a structured laser light to acquire dense transverse profiles of a pavement lane surface when it carries a moving vehicle. After the calibration, the 3D system can yield a depth resolution of 0.5 mm and a transverse resolution of 1.56 mm pixel −1 at 1.4 m camera height from the ground. The scanning rate of the camera can be set to its maximum at 5000 lines s −1 , allowing the density of scanned profiles to vary with the vehicle's speed. The paper then illustrates the algorithms that utilize 3D information to detect pavement distress, such as transverse, longitudinal and alligator cracking, and presents the field tests on the system's repeatability when scanning a sample pavement in multiple runs at the same vehicle speed, at different vehicle speeds and under different weather conditions. The results show that this dedicated 3D system can capture accurate pavement images that detail surface distress, and obtain consistent crack measurements in repeated tests and under different driving and lighting conditions. (paper)

  6. Resonance γ-ray polarimetry

    International Nuclear Information System (INIS)

    Gonser, U.; Fischer, H.

    1981-01-01

    The topics are: Intensity and polarization of radiation in Moessbauer transitions, hyperfine interactions in 57 Fe, polarized γ-rays, polarimetry, γ-ray rotation polarimeters, Birefringence polarimetry. (WL)

  7. Research on calibration algorithm in laser scanning projection system

    Science.gov (United States)

    Li, Li Juan; Qu, Song; Hou, Mao Sheng

    2017-10-01

    Laser scanning projection technology can project the image defined by the existing CAD digital model to the working surface, in the form of a laser harness profile. This projection is in accordance with the ratio of 1: 1. Through the laser harness contours with high positioning quality, the technical staff can carry out the operation with high precision. In a typical process of the projection, in order to determine the relative positional relationship between the laser projection instrument and the target, it is necessary to place several fixed reference points on the projection target and perform the calibration of projection. This position relationship is the transformation from projection coordinate system to the global coordinate system. The entire projection work is divided into two steps: the first step, the calculation of the projector six position parameters is performed, that is, the projector calibration. In the second step, the deflection angle is calculated by the known projector position parameter and the known coordinate points, and then the actual model is projected. Typically, the calibration requires the establishment of six reference points to reduce the possibility of divergence of the nonlinear equations, but the whole solution is very complex and the solution may still diverge. In this paper, the distance is detected combined with the calculation so that the position parameters of the projector can be solved by using the coordinate values of three reference points and the distance of at least one reference point to the projector. The addition of the distance measurement increases the stability of the solution of the nonlinear system and avoids the problem of divergence of the solution caused by the reference point which is directly under the projector. Through the actual analysis and calculation, the Taylor expansion method combined with the least squares method is used to obtain the solution of the system. Finally, the simulation experiment is

  8. Terrestrial Laser Scanning-Based Bridge Structural Condition Assessment : Tech Transfer Summaries

    Science.gov (United States)

    2016-05-01

    Problem Statement : While several state departments of transportation (DOTs) have used : terrestrial laser scanning (TLS) in the project planning phase, limited : research has been conducted on employing laser scanners to detect : cracks for bridge c...

  9. Classification of Mobile Laser Scanning Point Clouds from Height Features

    Science.gov (United States)

    Zheng, M.; Lemmens, M.; van Oosterom, P.

    2017-09-01

    The demand for 3D maps of cities and road networks is steadily growing and mobile laser scanning (MLS) systems are often the preferred geo-data acquisition method for capturing such scenes. Because MLS systems are mounted on cars or vans they can acquire billions of points of road scenes within a few hours of survey. Manual processing of point clouds is labour intensive and thus time consuming and expensive. Hence, the need for rapid and automated methods for 3D mapping of dense point clouds is growing exponentially. The last five years the research on automated 3D mapping of MLS data has tremendously intensified. In this paper, we present our work on automated classification of MLS point clouds. In the present stage of the research we exploited three features - two height components and one reflectance value, and achieved an overall accuracy of 73 %, which is really encouraging for further refining our approach.

  10. Signal and noise modeling in confocal laser scanning fluorescence microscopy.

    Science.gov (United States)

    Herberich, Gerlind; Windoffer, Reinhard; Leube, Rudolf E; Aach, Til

    2012-01-01

    Fluorescence confocal laser scanning microscopy (CLSM) has revolutionized imaging of subcellular structures in biomedical research by enabling the acquisition of 3D time-series of fluorescently-tagged proteins in living cells, hence forming the basis for an automated quantification of their morphological and dynamic characteristics. Due to the inherently weak fluorescence, CLSM images exhibit a low SNR. We present a novel model for the transfer of signal and noise in CLSM that is both theoretically sound as well as corroborated by a rigorous analysis of the pixel intensity statistics via measurement of the 3D noise power spectra, signal-dependence and distribution. Our model provides a better fit to the data than previously proposed models. Further, it forms the basis for (i) the simulation of the CLSM imaging process indispensable for the quantitative evaluation of CLSM image analysis algorithms, (ii) the application of Poisson denoising algorithms and (iii) the reconstruction of the fluorescence signal.

  11. Monitoring of Progressive Damage in Buildings Using Laser Scan Data

    Science.gov (United States)

    Puente, I.; Lindenbergh, R.; Van Natijne, A.; Esposito, R.; Schipper, R.

    2018-05-01

    Vulnerability of buildings to natural and man-induced hazards has become a main concern for our society. Ensuring their serviceability, safety and sustainability is of vital importance and the main reason for setting up monitoring systems to detect damages at an early stage. In this work, a method is presented for detecting changes from laser scan data, where no registration between different epochs is needed. To show the potential of the method, a case study of a laboratory test carried out at the Stevin laboratory of Delft University of Technology was selected. The case study was a quasi-static cyclic pushover test on a two-story high unreinforced masonry structure designed to simulate damage evolution caused by cyclic loading. During the various phases, we analysed the behaviour of the masonry walls by monitoring the deformation of each masonry unit. First a plane is fitted to the selected wall point cloud, consisting of one single terrestrial laser scan, using Principal Component Analysis (PCA). Second, the segmentation of individual elements is performed. Then deformations with respect to this plane model, for each epoch and specific element, are determined by computing their corresponding rotation and cloud-to-plane distances. The validation of the changes detected within this approach is done by comparison with traditional deformation analysis based on co-registered TLS point clouds between two or more epochs of building measurements. Initial results show that the sketched methodology is indeed able to detect changes at the mm level while avoiding 3D point cloud registration, which is a main issue in computer vision and remote sensing.

  12. AUTOMATIC EXTRACTION OF ROAD MARKINGS FROM MOBILE LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    H. Ma

    2017-09-01

    Full Text Available Road markings as critical feature in high-defination maps, which are Advanced Driver Assistance System (ADAS and self-driving technology required, have important functions in providing guidance and information to moving cars. Mobile laser scanning (MLS system is an effective way to obtain the 3D information of the road surface, including road markings, at highway speeds and at less than traditional survey costs. This paper presents a novel method to automatically extract road markings from MLS point clouds. Ground points are first filtered from raw input point clouds using neighborhood elevation consistency method. The basic assumption of the method is that the road surface is smooth. Points with small elevation-difference between neighborhood are considered to be ground points. Then ground points are partitioned into a set of profiles according to trajectory data. The intensity histogram of points in each profile is generated to find intensity jumps in certain threshold which inversely to laser distance. The separated points are used as seed points to region grow based on intensity so as to obtain road mark of integrity. We use the point cloud template-matching method to refine the road marking candidates via removing the noise clusters with low correlation coefficient. During experiment with a MLS point set of about 2 kilometres in a city center, our method provides a promising solution to the road markings extraction from MLS data.

  13. Automatic Extraction of Road Markings from Mobile Laser Scanning Data

    Science.gov (United States)

    Ma, H.; Pei, Z.; Wei, Z.; Zhong, R.

    2017-09-01

    Road markings as critical feature in high-defination maps, which are Advanced Driver Assistance System (ADAS) and self-driving technology required, have important functions in providing guidance and information to moving cars. Mobile laser scanning (MLS) system is an effective way to obtain the 3D information of the road surface, including road markings, at highway speeds and at less than traditional survey costs. This paper presents a novel method to automatically extract road markings from MLS point clouds. Ground points are first filtered from raw input point clouds using neighborhood elevation consistency method. The basic assumption of the method is that the road surface is smooth. Points with small elevation-difference between neighborhood are considered to be ground points. Then ground points are partitioned into a set of profiles according to trajectory data. The intensity histogram of points in each profile is generated to find intensity jumps in certain threshold which inversely to laser distance. The separated points are used as seed points to region grow based on intensity so as to obtain road mark of integrity. We use the point cloud template-matching method to refine the road marking candidates via removing the noise clusters with low correlation coefficient. During experiment with a MLS point set of about 2 kilometres in a city center, our method provides a promising solution to the road markings extraction from MLS data.

  14. PEDESTRIAN DETECTION BY LASER SCANNING AND DEPTH IMAGERY

    Directory of Open Access Journals (Sweden)

    A. Barsi

    2016-06-01

    Full Text Available Pedestrian flow is much less regulated and controlled compared to vehicle traffic. Estimating flow parameters would support many safety, security or commercial applications. Current paper discusses a method that enables acquiring information on pedestrian movements without disturbing and changing their motion. Profile laser scanner and depth camera have been applied to capture the geometry of the moving people as time series. Procedures have been developed to derive complex flow parameters, such as count, volume, walking direction and velocity from laser scanned point clouds. Since no images are captured from the faces of pedestrians, no privacy issues raised. The paper includes accuracy analysis of the estimated parameters based on video footage as reference. Due to the dense point clouds, detailed geometry analysis has been conducted to obtain the height and shoulder width of pedestrians and to detect whether luggage has been carried or not. The derived parameters support safety (e.g. detecting critical pedestrian density in mass events, security (e.g. detecting prohibited baggage in endangered areas and commercial applications (e.g. counting pedestrians at all entrances/exits of a shopping mall.

  15. Pedestrian Detection by Laser Scanning and Depth Imagery

    Science.gov (United States)

    Barsi, A.; Lovas, T.; Molnar, B.; Somogyi, A.; Igazvolgyi, Z.

    2016-06-01

    Pedestrian flow is much less regulated and controlled compared to vehicle traffic. Estimating flow parameters would support many safety, security or commercial applications. Current paper discusses a method that enables acquiring information on pedestrian movements without disturbing and changing their motion. Profile laser scanner and depth camera have been applied to capture the geometry of the moving people as time series. Procedures have been developed to derive complex flow parameters, such as count, volume, walking direction and velocity from laser scanned point clouds. Since no images are captured from the faces of pedestrians, no privacy issues raised. The paper includes accuracy analysis of the estimated parameters based on video footage as reference. Due to the dense point clouds, detailed geometry analysis has been conducted to obtain the height and shoulder width of pedestrians and to detect whether luggage has been carried or not. The derived parameters support safety (e.g. detecting critical pedestrian density in mass events), security (e.g. detecting prohibited baggage in endangered areas) and commercial applications (e.g. counting pedestrians at all entrances/exits of a shopping mall).

  16. Mechanisms of biliary stent clogging: confocal laser scanning and scanning electron microscopy.

    Science.gov (United States)

    van Berkel, A M; van Marle, J; Groen, A K; Bruno, M J

    2005-08-01

    Endoscopic insertion of plastic biliary endoprostheses is a well-established treatment for obstructive jaundice. The major limitation of this technique is late stent occlusion. In order to compare events involved in biliary stent clogging and identify the distribution of bacteria in unblocked stents, confocal laser scanning (CLS) and scanning electron microscopy (SEM) were carried out on two different stent materials - polyethylene (PE) and hydrophilic polymer-coated polyurethane (HCPC). Ten consecutive patients with postoperative benign biliary strictures were included in the study. Two 10-Fr stents 9 cm in length, one made of PE and the other of HCPC, were inserted. The stents were electively exchanged after 3 months and examined using CLS and SEM. No differences were seen between the two types of stent. The inner stent surface was covered with a uniform amorphous layer. On top of this layer, a biofilm of living and dead bacteria was found, which in most cases was unstructured. The lumen was filled with free-floating colonies of bacteria and crystals, surrounded by mobile laminar structures of mucus. An open network of large dietary fibers was seen in all of the stents. The same clogging events occurred in both PE and HCPC stents. The most remarkable observation was the identification of networks of large dietary fibers, resulting from duodenal reflux, acting as a filter. The build-up of this intraluminal framework of dietary fibers appears to be a major factor contributing to the multifactorial process of stent clogging.

  17. Long-term efficacy of linear-scanning 808 nm diode laser for hair removal compared to a scanned alexandrite laser.

    Science.gov (United States)

    Grunewald, Sonja; Bodendorf, Marc Oliver; Zygouris, Alexander; Simon, Jan Christoph; Paasch, Uwe

    2014-01-01

    Alexandrite and diode lasers are commonly used for hair removal. To date, the available spot sizes and repetition rates are defining factors in terms of penetration depth, treatment speed, and efficacy. Still, larger treatment areas and faster systems are desirable. To compare the efficacy, tolerability, and subject satisfaction of a continuously linear-scanning 808 nm diode laser with an alexandrite 755 nm laser for axillary hair removal. A total of 31 adults with skin types I-IV received 6 treatments at 4-week intervals with a 755 nm alexandrite laser (right axilla) and a continuously linear-scanning 808 nm diode laser (left axilla). Axillary hair density was assessed using a computerized hair detection system. There was a significant reduction in axillary hair after the 6th treatment (P lasers was not significant, but both were persistant at 18 months follow-up (left: hair clearance of 73.71%; right: hair clearance of 71.90%). Erythema and perifollicular edema were more common after alexandrite laser treatment, but all side effects were transient. While 62.50% of patients reported more pain in response to treatment with the new diode laser, all patients rated treatment with either laser tolerable. Treatment with either the alexandrite or the linear-scanning diode laser results in significant, comparable, persistent (at least 18 months) axillary hair reduction among individuals with skin types I-IV. © 2013 Wiley Periodicals, Inc.

  18. Deformation Monitoring of Motorway Underpasses Using Laser Scanning Data

    Science.gov (United States)

    Puente, I.; González-Jorge, H.; Riveiro, B.; Arias, P.

    2012-07-01

    is a Optech Lynx mobile LiDAR. This laser scanner is based on time of flight technology and presents an accuracy of 6 mm in the determination of the geometrical coordinates. This accuracy can be improved to around 1 mm using fitting post-processing techniques and makes this technology very useful for studies related with deformation monitoring. The laser scanner, in comparison with other geodetic techniques as total stations, allows the control of all the structure, including unexpected deformations. Reflective targets are permanently positioned over the small walls of the structure to allow the 3D orientation of the different scans. Two main scans are made for this study, before and after the backfilling process. Backfilling takes about 10 days for the construction companies. The scans need a time of approximately 12 minutes. Construction works do not need to be interrupted during the scans. Point clouds are then post-processed using QT Modeler Software. First, the point cloud is cleaned to use only the data directly related with the structure under study. Then, using the target coordinates, both point clouds are moved to the same coordinate system. Finally, the deformation of the underpass is studied using two algorithms specifically developed using Matlab software. First algorithm fits a geometrical surface to the point cloud of the first scan and evaluates the residuals of both scans for this fitting surface. Differences in the residuals give the deformation map of the structure. Second algorithm takes a portion of the point cloud from the top of the structure, where it is located the joining point between the voussoirs. The joining between two voussoirs shows a height step that in an ideal case must tend to zero. Deformations produced by the loading of the structure are measured as a comparison between the steps before and after the backfilling process. The analysis of the results show as some deformation occurs in the structure in the joining point of the

  19. DEFORMATION MONITORING OF MOTORWAY UNDERPASSES USING LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    I. Puente

    2012-07-01

    deformation monitoring is a Optech Lynx mobile LiDAR. This laser scanner is based on time of flight technology and presents an accuracy of 6 mm in the determination of the geometrical coordinates. This accuracy can be improved to around 1 mm using fitting post-processing techniques and makes this technology very useful for studies related with deformation monitoring. The laser scanner, in comparison with other geodetic techniques as total stations, allows the control of all the structure, including unexpected deformations. Reflective targets are permanently positioned over the small walls of the structure to allow the 3D orientation of the different scans. Two main scans are made for this study, before and after the backfilling process. Backfilling takes about 10 days for the construction companies. The scans need a time of approximately 12 minutes. Construction works do not need to be interrupted during the scans. Point clouds are then post-processed using QT Modeler Software. First, the point cloud is cleaned to use only the data directly related with the structure under study. Then, using the target coordinates, both point clouds are moved to the same coordinate system. Finally, the deformation of the underpass is studied using two algorithms specifically developed using Matlab software. First algorithm fits a geometrical surface to the point cloud of the first scan and evaluates the residuals of both scans for this fitting surface. Differences in the residuals give the deformation map of the structure. Second algorithm takes a portion of the point cloud from the top of the structure, where it is located the joining point between the voussoirs. The joining between two voussoirs shows a height step that in an ideal case must tend to zero. Deformations produced by the loading of the structure are measured as a comparison between the steps before and after the backfilling process. The analysis of the results show as some deformation occurs in the structure in the joining

  20. HIGH ENERGY HADRON POLARIMETRY

    International Nuclear Information System (INIS)

    BUNCE, G.

    2007-01-01

    Proton polarimetry at RHIC uses the interference of electromagnetic (EM) and hadronic scattering amplitudes. The EM spin-flip amplitude for protons is responsible for the proton's anomalous magnetic moment, and is large. This then generates a significant analyzing power for small angle elastic scattering. RHIC polarimetry has reached a 5% uncertainty on the beam polarization, and seem capable of reducing this uncertainty further. Polarized neutron beams ax also interesting for RHIC and for a polarized electron-polarized proton/ion collider in the fume. In this case, deuterons, for example, have a very small anomalous magnetic moment, making the approach used for protons impractical. Although it might be possible to use quasielastic scattering from the protons in the deuteron to monitor the polarization. 3-He beams can provide polarized neutrons, and do have a large anomalous magnetic moment, making a similar approach to proton polarimetry possible

  1. Surveying a fossil oyster reef using terrestrial laser scanning

    Science.gov (United States)

    Haring, A.; Exner, U.; Harzhauser, M.

    2009-04-01

    The Korneuburg Basin, situated north-west of Vienna, is well known to contain a rich variety of fossils from the Early Miocene (16.5 ma) and therefore has been investigated extensively by scientists in the past decades. An exceptional discovery was made in 2005: a large fossil oyster reef has been excavated and documented carefully during the last years. Aside from the giant-sized oyster (Crassostrea gryphoides), the excavation site contains numerous species of molluscs along with teeth of sharks and rays and even isolated bones of sea cows. The oysters, having lengths of up to 80 cm, are protruding from the ground surface, which is more or less a tilted plane (25˚ ) with a size of about 300 m2. The entire site is crosscut by a network of geological faults, often also offsetting individual oyster shells. Displacements along the normal faults do not exceed ~ 15 cm. The faulted fossils offer a unique opportunity to measure displacement distribution along the faults in great detail and provide insight in deformation mechanisms in porous, barely lithified sediments. In order to get a precise 3D model of the oyster reef, the terrestrial laser scanner system Leica HDS 6000 is used. It is a phase-based laser scanner, i.e. the distance measurement is performed using the phase-shift principle. Compared to the time-of-flight principle, this method is generally more appropriate to projects like this one, where the distances to be measured are relatively small (< 35 m) and where a high point density (point spacing of about 1 cm) and precision (some mm) is required for capturing the oysters adequately. However, due to fact that they occlude each other, one single scan is not sufficient to get all sides of their surface. Therefore, scans from different positions had to be acquired. These scans have to be merged, which involves the problem of sensor orientation as well as sampling of the entire 3D point cloud. Furthermore, a representation of the surface data is required that

  2. Estimation of forest resources from a country wide laser scanning survey and national forest inventory data

    DEFF Research Database (Denmark)

    Nord-Larsen, Thomas; Schumacher, Johannes

    2012-01-01

    Airborne laser scanning may provide a means for assessing local forest biomass resources. In this study, national forest inventory (NFI) data was used as reference data for modeling forest basal area, volume, aboveground biomass, and total biomass from laser scanning data obtained in a countrywid...

  3. Tree Classification with Fused Mobile Laser Scanning and Hyperspectral Data

    Science.gov (United States)

    Puttonen, Eetu; Jaakkola, Anttoni; Litkey, Paula; Hyyppä, Juha

    2011-01-01

    Mobile Laser Scanning data were collected simultaneously with hyperspectral data using the Finnish Geodetic Institute Sensei system. The data were tested for tree species classification. The test area was an urban garden in the City of Espoo, Finland. Point clouds representing 168 individual tree specimens of 23 tree species were determined manually. The classification of the trees was done using first only the spatial data from point clouds, then with only the spectral data obtained with a spectrometer, and finally with the combined spatial and hyperspectral data from both sensors. Two classification tests were performed: the separation of coniferous and deciduous trees, and the identification of individual tree species. All determined tree specimens were used in distinguishing coniferous and deciduous trees. A subset of 133 trees and 10 tree species was used in the tree species classification. The best classification results for the fused data were 95.8% for the separation of the coniferous and deciduous classes. The best overall tree species classification succeeded with 83.5% accuracy for the best tested fused data feature combination. The respective results for paired structural features derived from the laser point cloud were 90.5% for the separation of the coniferous and deciduous classes and 65.4% for the species classification. Classification accuracies with paired hyperspectral reflectance value data were 90.5% for the separation of coniferous and deciduous classes and 62.4% for different species. The results are among the first of their kind and they show that mobile collected fused data outperformed single-sensor data in both classification tests and by a significant margin. PMID:22163894

  4. Experimental verification of subthreshold laser therapy using conventional pattern scan laser.

    Directory of Open Access Journals (Sweden)

    Tomoyasu Shiraya

    Full Text Available Leading-edge therapeutic laser technologies are not available at every medical facility; therefore, alternative approaches incorporating novel advances in digital and laser technology into more readily available conventional methods have generated significant research interest. Using a rabbit model, this study investigated whether the algorithm used in the Endpoint Management (EM software system of the latest devices could enable subthreshold laser treatment in conventional retinal tissue laser therapy systems.Two types of devices were used, the PASCAL Streamline 577 and the MC 500-Vixi™, and the laser method was classified into three categories: EM; single-shot using PASCAL with arbitrary energy settings (PSS-SDM; and MC500-VixiTM (VX-SDM, which were performed in eight eyes from four Dutch-Belted rabbits. In EM, 100 mW (100% was set as a landmark, and the laser energy parameters were gradually decreased to 80%, 60%, 50%, 40%, 30%, 20%, and 10%, using a 2 × 3 square pattern. In PSS-SDM and VX-SDM, as control, the laser energy was gradually decreased to 100, 80, 60, 50, 40, 30, 20, and 10 mW. The laser settings were fixed at 200 μm, 20 ms, and a wavelength of 577 μm. To identify and compare the extent of tissue damage at each spot size, optical coherence tomography (OCT and histological findings were used to construct a three-dimensional histopathology image using a confocal laser scanning fluorescence microscope.The spot size at 50% setting on EM was 7183 μm2; PSS-SDM required 50 mW (5503 μm2 to 60 mW (10279 μm2 and VX-SDM required 50 mW (7423 μm2 to create the approximate spot size. Furthermore, at 50 mW of PSS-SDM and VX-SDM, the extent of tissue damage in all three methods was generally in accord with the outer nuclear layer by OCT and inner nuclear layer by histopathological imaging.These findings suggest that it may be possible to perform subthreshold laser therapy using approximations from the EM algorithm.

  5. Pattern scan laser versus single spot laser in panretinal photocoagulation treatment for proliferative diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Shu Zhang

    2017-02-01

    Full Text Available AIM: To investigate the efficacy of 577-nm pattern scan laser in panretinal photocoagulation(PRPtreatment in newly diagnosed proliferative diabetic retinopathy(PDR.METHODS:Prospective and comparative observation was performed in totally 32 patients with high-risk PDR. They were randomly divided into group 1(using pattern scan laser, PSLand 2(using single spot laser, SSL, each containing 16 subjects to which totally 20 eyes received PRP. Non-perfusion region was identified with fundus fluorescein angiography(FFAbefore and 3mo after final PRP. The advantage of PSL was verified in terms of the number and the duration of PRP sessions needed for satisfactory outcomes, and the pain score.RESULTS: Three PRP sessions were needed for each eye to complete the treatment using PSL, while 4 sessions were needed using SSL. The duration of each session with PSL in group 1 was 7.3±2.3min, which was significantly shorter than that with SSL in group 2(13.2±4.1, t38=5.596, PPCONCLUSION: PSL showed clear advantages over SSL in the PRP treatment of PDR, not only in the improved efficacy, but also in the reduction of pain and the improvement of effectiveness.

  6. Laser scanning dental probe for endodontic root canal treatment

    Science.gov (United States)

    Blank, Molly A. B.; Friedrich, Michal; Hamilton, Jeffrey D.; Lee, Peggy; Berg, Joel; Seibel, Eric J.

    2011-03-01

    Complications that arise during endodontic procedures pose serious threats to the long-term integrity and health of the tooth. Potential complexities of root canals include residual pulpal tissue, cracks, mesial-buccal 2 and accessory canals. In the case of a failed root canal, a successful apicoectomy can be jeopardized by isthmuses, accessory canals, and root microfracture. Confirming diagnosis using a small imaging probe would allow proper treatment and prevent retreatment of endodontic procedures. An ultrathin and flexible laser scanning endoscope of 1.2 to 1.6mm outer diameter was used in vitro to image extracted teeth with varied root configurations. Teeth were opened using a conventional bur and high speed drill. Imaging within the opened access cavity clarified the location of the roots where canal filing would initiate. Although radiographs are commonly used to determine the root canal size, position, and shape, the limited 2D image perspective leaves ambiguity that could be clarified if used in conjunction with a direct visual imaging tool. Direct visualization may avoid difficulties in locating the root canal and reduce the number of radiographs needed. A transillumination imaging device with the separated illumination and light collection functions rendered cracks visible in the prepared teeth that were otherwise indiscernible using reflected visible light. Our work demonstrates that a small diameter endoscope with high spatial resolution may significantly increase the efficiency and success of endodontic procedures.

  7. AN AUTOMATED ROAD ROUGHNESS DETECTION FROM MOBILE LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    P. Kumar

    2017-05-01

    Full Text Available Rough roads influence the safety of the road users as accident rate increases with increasing unevenness of the road surface. Road roughness regions are required to be efficiently detected and located in order to ensure their maintenance. Mobile Laser Scanning (MLS systems provide a rapid and cost-effective alternative by providing accurate and dense point cloud data along route corridor. In this paper, an automated algorithm is presented for detecting road roughness from MLS data. The presented algorithm is based on interpolating smooth intensity raster surface from LiDAR point cloud data using point thinning process. The interpolated surface is further processed using morphological and multi-level Otsu thresholding operations to identify candidate road roughness regions. The candidate regions are finally filtered based on spatial density and standard deviation of elevation criteria to detect the roughness along the road surface. The test results of road roughness detection algorithm on two road sections are presented. The developed approach can be used to provide comprehensive information to road authorities in order to schedule maintenance and ensure maximum safety conditions for road users.

  8. An Automated Road Roughness Detection from Mobile Laser Scanning Data

    Science.gov (United States)

    Kumar, P.; Angelats, E.

    2017-05-01

    Rough roads influence the safety of the road users as accident rate increases with increasing unevenness of the road surface. Road roughness regions are required to be efficiently detected and located in order to ensure their maintenance. Mobile Laser Scanning (MLS) systems provide a rapid and cost-effective alternative by providing accurate and dense point cloud data along route corridor. In this paper, an automated algorithm is presented for detecting road roughness from MLS data. The presented algorithm is based on interpolating smooth intensity raster surface from LiDAR point cloud data using point thinning process. The interpolated surface is further processed using morphological and multi-level Otsu thresholding operations to identify candidate road roughness regions. The candidate regions are finally filtered based on spatial density and standard deviation of elevation criteria to detect the roughness along the road surface. The test results of road roughness detection algorithm on two road sections are presented. The developed approach can be used to provide comprehensive information to road authorities in order to schedule maintenance and ensure maximum safety conditions for road users.

  9. Measuring Leaf Water Content Using Multispectral Terrestrial Laser Scanning

    Science.gov (United States)

    Junttila, S.; Vastaranta, M.; Linnakoski, R.; Sugano, J.; Kaartinen, H.; Kukko, A.; Holopainen, M.; Hyyppä, H.; Hyyppä, J.

    2017-10-01

    Climate change is increasing the amount and intensity of disturbance events, i.e. drought, pest insect outbreaks and fungal pathogens, in forests worldwide. Leaf water content (LWC) is an early indicator of tree stress that can be measured remotely using multispectral terrestrial laser scanning (MS-TLS). LWC affects leaf reflectance in the shortwave infrared spectrum which can be used to predict LWC from spatially explicit MS-TLS intensity data. Here, we investigated the relationship between LWC and MS-TLS intensity features at 690 nm, 905 nm and 1550 nm wavelengths with Norway spruce seedlings in greenhouse conditions. We found that a simple ratio of 905 nm and 1550 nm wavelengths was able to explain 84 % of the variation (R2) in LWC with a respective prediction accuracy of 0.0041 g/cm2. Our results showed that MS-TLS can be used to estimate LWC with a reasonable accuracy in environmentally stable conditions.

  10. Hierarchical extraction of urban objects from mobile laser scanning data

    Science.gov (United States)

    Yang, Bisheng; Dong, Zhen; Zhao, Gang; Dai, Wenxia

    2015-01-01

    Point clouds collected in urban scenes contain a huge number of points (e.g., billions), numerous objects with significant size variability, complex and incomplete structures, and variable point densities, raising great challenges for the automated extraction of urban objects in the field of photogrammetry, computer vision, and robotics. This paper addresses these challenges by proposing an automated method to extract urban objects robustly and efficiently. The proposed method generates multi-scale supervoxels from 3D point clouds using the point attributes (e.g., colors, intensities) and spatial distances between points, and then segments the supervoxels rather than individual points by combining graph based segmentation with multiple cues (e.g., principal direction, colors) of the supervoxels. The proposed method defines a set of rules for merging segments into meaningful units according to types of urban objects and forms the semantic knowledge of urban objects for the classification of objects. Finally, the proposed method extracts and classifies urban objects in a hierarchical order ranked by the saliency of the segments. Experiments show that the proposed method is efficient and robust for extracting buildings, streetlamps, trees, telegraph poles, traffic signs, cars, and enclosures from mobile laser scanning (MLS) point clouds, with an overall accuracy of 92.3%.

  11. Monitoring Riverbank Erosion in Mountain Catchments Using Terrestrial Laser Scanning

    Directory of Open Access Journals (Sweden)

    Laura Longoni

    2016-03-01

    Full Text Available Sediment yield is a key factor in river basins management due to the various and adverse consequences that erosion and sediment transport in rivers may have on the environment. Although various contributions can be found in the literature about sediment yield modeling and bank erosion monitoring, the link between weather conditions, river flow rate and bank erosion remains scarcely known. Thus, a basin scale assessment of sediment yield due to riverbank erosion is an objective hard to be reached. In order to enhance the current knowledge in this field, a monitoring method based on high resolution 3D model reconstruction of riverbanks, surveyed by multi-temporal terrestrial laser scanning, was applied to four banks in Val Tartano, Northern Italy. Six data acquisitions over one year were taken, with the aim to better understand the erosion processes and their triggering factors by means of more frequent observations compared to usual annual campaigns. The objective of the research is to address three key questions concerning bank erosion: “how” erosion happens, “when” during the year and “how much” sediment is eroded. The method proved to be effective and able to measure both eroded and deposited volume in the surveyed area. Finally an attempt to extrapolate basin scale volume for bank erosion is presented.

  12. MEASURING LEAF WATER CONTENT USING MULTISPECTRAL TERRESTRIAL LASER SCANNING

    Directory of Open Access Journals (Sweden)

    S. Junttila

    2017-10-01

    Full Text Available Climate change is increasing the amount and intensity of disturbance events, i.e. drought, pest insect outbreaks and fungal pathogens, in forests worldwide. Leaf water content (LWC is an early indicator of tree stress that can be measured remotely using multispectral terrestrial laser scanning (MS-TLS. LWC affects leaf reflectance in the shortwave infrared spectrum which can be used to predict LWC from spatially explicit MS-TLS intensity data. Here, we investigated the relationship between LWC and MS-TLS intensity features at 690 nm, 905 nm and 1550 nm wavelengths with Norway spruce seedlings in greenhouse conditions. We found that a simple ratio of 905 nm and 1550 nm wavelengths was able to explain 84 % of the variation (R2 in LWC with a respective prediction accuracy of 0.0041 g/cm2. Our results showed that MS-TLS can be used to estimate LWC with a reasonable accuracy in environmentally stable conditions.

  13. Confocal laser scanning microscopy in study of bone calcification

    Science.gov (United States)

    Nishikawa, Tetsunari; Kokubu, Mayu; Kato, Hirohito; Imai, Koichi; Tanaka, Akio

    2012-12-01

    Bone regeneration in mandible and maxillae after extraction of teeth or tumor resection and the use of rough surface implants in bone induction must be investigated to elucidate the mechanism of calcification. The calcified tissues are subjected to chemical decalcification or physical grinding to observe their microscopic features with light microscopy and transmission electron microscopy where the microscopic tissue morphology is significantly altered. We investigated the usefulness of confocal laser scanning microscopy (CLSM) for this purpose. After staggering the time of administration of calcein and alizarin red to experimental rats and dogs, rat alveolar bone and dog femur grafted with coral as scaffold or dental implants were observed with CLSM. In rat alveolar bone, the calcification of newly-formed bone and net-like canaliculi was observed at the mesial bone from the roots progressed at the rate of 15 μm/day. In dog femur grafted with coral, newly-formed bones along the space of coral were observed in an orderly manner. In dog femur with dental implants, after 8 weeks, newly-formed bone proceeded along the rough surface of the implants. CLSM produced high-magnification images of newly-formed bone and thin sections were not needed.

  14. Wetland Microtopographic Structure is Revealed with Terrestrial Laser Scanning

    Science.gov (United States)

    Diamond, J.; Stovall, A. E.; Mclaughlin, D. L.; Slesak, R.

    2017-12-01

    Wetland microtopographic structure and its function has been the subject of research for decades, and several investigations suggest that microtopography is generated by autogenic ecohydrologic processes. But due to the difficulty of capturing the true spatial variability of wetland microtopography, many of the hypotheses for self-organization have remained elusive to test. We employ a novel method of Terrestrial Laser Scanning (TLS) that reveals an unprecedented high-resolution (structure of wetland microtopography in 10 black ash (Fraxinus nigra) stands of northern Minnesota, USA. Here we present the first efforts to synthesize this information and show that TLS provides a good representation of real microtopographic structure, where TLS accurately measured hummock height, but occlusion of low points led to a slight negative bias. We further show that TLS can accurately locate microtopographic high points (hummocks), as well as estimate their height and area. Using these new data, we estimate distributions in both microtopographic elevation and hummock area in each wetland and relate these to monitored hydrologic regime; in doing so, we test hypotheses linking emergent microtopographic patterns to putative hydrologic controls. Finally, we discuss future efforts to enumerate consequent influences of microtopography on wetland systems (soil properties and vegetation composition).

  15. Detecting Terrain Stoniness From Airborne Laser Scanning Data †

    Directory of Open Access Journals (Sweden)

    Paavo Nevalainen

    2016-08-01

    Full Text Available Three methods to estimate the presence of ground surface stones from publicly available Airborne Laser Scanning (ALS point clouds are presented. The first method approximates the local curvature by local linear multi-scale fitting, and the second method uses Discrete-Differential Gaussian curvature based on the ground surface triangulation. The third baseline method applies Laplace filtering to Digital Elevation Model (DEM in a 2 m regular grid data. All methods produce an approximate Gaussian curvature distribution which is then vectorized and classified by logistic regression. Two training data sets consisted of 88 and 674 polygons of mass-flow deposits, respectively. The locality of the polygon samples is a sparse canopy boreal forest, where the density of ALS ground returns is sufficiently high to reveal information about terrain micro-topography. The surface stoniness of each polygon sample was categorized for supervised learning by expert observation on the site. The leave-pair-out (L2O cross-validation of the local linear fit method results in the area under curve A U C = 0 . 74 and A U C = 0 . 85 on two data sets, respectively. This performance can be expected to suit real world applications such as detecting coarse-grained sediments for infrastructure construction. A wall-to-wall predictor based on the study was demonstrated.

  16. Laser scanning measurements on trees for logging harvesting operations.

    Science.gov (United States)

    Zheng, Yili; Liu, Jinhao; Wang, Dian; Yang, Ruixi

    2012-01-01

    Logging harvesters represent a set of high-performance modern forestry machinery, which can finish a series of continuous operations such as felling, delimbing, peeling, bucking and so forth with human intervention. It is found by experiment that during the process of the alignment of the harvesting head to capture the trunk, the operator needs a lot of observation, judgment and repeated operations, which lead to the time and fuel losses. In order to improve the operation efficiency and reduce the operating costs, the point clouds for standing trees are collected with a low-cost 2D laser scanner. A cluster extracting algorithm and filtering algorithm are used to classify each trunk from the point cloud. On the assumption that every cross section of the target trunk is approximate a standard circle and combining the information of an Attitude and Heading Reference System, the radii and center locations of the trunks in the scanning range are calculated by the Fletcher-Reeves conjugate gradient algorithm. The method is validated through experiments in an aspen forest, and the optimized calculation time consumption is compared with the previous work of other researchers. Moreover, the implementation of the calculation result for automotive capturing trunks by the harvesting head during the logging operation is discussed in particular.

  17. RANSAC approach for automated registration of terrestrial laser scans using linear features

    Directory of Open Access Journals (Sweden)

    K. Al-Durgham

    2013-10-01

    Full Text Available The registration process of terrestrial laser scans (TLS targets the problem of how to combine several laser scans in order to attain better information about features than what could be obtained through single scan. The main goal of the registration process is to estimate the parameters which determine geometrical variation between the origins of datasets collected from different locations. Scale, shifts, and rotation parameters are usually used to describe such variation. This paper presents a framework for the registration of overlapping terrestrial laser scans by establishing an automatic matching strategy that uses 3D linear features. More specifically, invariant separation characteristics between 3D linear features extracted from laser scans will be used to establish hypothesized conjugate linear features between the laser scans. These candidate matches are then used to geo-reference scans relative to a common reference frame. The registration workflow simulates the well-known RANndom Sample Consensus method (RANSAC for determining the registration parameters, whereas the iterative closest projected point (ICPP is utilized to determine the most probable solution of the transformation parameters from several solutions. The experimental results prove that the proposed methodology can be used for the automatic registration of terrestrial laser scans using linear features.

  18. Confocal laser scanning microscopy in study of bone calcification

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, Tetsunari, E-mail: tetsu-n@cc.osaka-dent.ac.jp [Department of Oral Pathology, Osaka Dental University, Osaka (Japan); Kokubu, Mayu; Kato, Hirohito [Department of Oral Pathology, Osaka Dental University, Osaka (Japan); Imai, Koichi [Department of Biomaterials, Osaka Dental University, Osaka (Japan); Tanaka, Akio [Department of Oral Pathology, Osaka Dental University, Osaka (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer High-magnification images with depth selection, and thin sections were observed using CLSM. Black-Right-Pointing-Pointer The direction and velocity of calcification of the bone was observed by administration of 2 fluorescent dyes. Black-Right-Pointing-Pointer In dog femora grafted with coral blocks, newly-formed bone was observed in the coral block space with a rough surface. Black-Right-Pointing-Pointer Twelve weeks after dental implant was grafted in dog femora, the space between screws was filled with newly-formed bones. - Abstract: Bone regeneration in mandible and maxillae after extraction of teeth or tumor resection and the use of rough surface implants in bone induction must be investigated to elucidate the mechanism of calcification. The calcified tissues are subjected to chemical decalcification or physical grinding to observe their microscopic features with light microscopy and transmission electron microscopy where the microscopic tissue morphology is significantly altered. We investigated the usefulness of confocal laser scanning microscopy (CLSM) for this purpose. After staggering the time of administration of calcein and alizarin red to experimental rats and dogs, rat alveolar bone and dog femur grafted with coral as scaffold or dental implants were observed with CLSM. In rat alveolar bone, the calcification of newly-formed bone and net-like canaliculi was observed at the mesial bone from the roots progressed at the rate of 15 {mu}m/day. In dog femur grafted with coral, newly-formed bones along the space of coral were observed in an orderly manner. In dog femur with dental implants, after 8 weeks, newly-formed bone proceeded along the rough surface of the implants. CLSM produced high-magnification images of newly-formed bone and thin sections were not needed.

  19. Confocal laser scanning microscopy in study of bone calcification

    International Nuclear Information System (INIS)

    Nishikawa, Tetsunari; Kokubu, Mayu; Kato, Hirohito; Imai, Koichi; Tanaka, Akio

    2012-01-01

    Highlights: ► High-magnification images with depth selection, and thin sections were observed using CLSM. ► The direction and velocity of calcification of the bone was observed by administration of 2 fluorescent dyes. ► In dog femora grafted with coral blocks, newly-formed bone was observed in the coral block space with a rough surface. ► Twelve weeks after dental implant was grafted in dog femora, the space between screws was filled with newly-formed bones. - Abstract: Bone regeneration in mandible and maxillae after extraction of teeth or tumor resection and the use of rough surface implants in bone induction must be investigated to elucidate the mechanism of calcification. The calcified tissues are subjected to chemical decalcification or physical grinding to observe their microscopic features with light microscopy and transmission electron microscopy where the microscopic tissue morphology is significantly altered. We investigated the usefulness of confocal laser scanning microscopy (CLSM) for this purpose. After staggering the time of administration of calcein and alizarin red to experimental rats and dogs, rat alveolar bone and dog femur grafted with coral as scaffold or dental implants were observed with CLSM. In rat alveolar bone, the calcification of newly-formed bone and net-like canaliculi was observed at the mesial bone from the roots progressed at the rate of 15 μm/day. In dog femur grafted with coral, newly-formed bones along the space of coral were observed in an orderly manner. In dog femur with dental implants, after 8 weeks, newly-formed bone proceeded along the rough surface of the implants. CLSM produced high-magnification images of newly-formed bone and thin sections were not needed.

  20. Development of Smart Precision Forest in Conifer Plantation in Japan Using Laser Scanning Data

    Science.gov (United States)

    Katoh, M.; Deng, S.; Takenaka, Y.; Cheung, K.; Oono, K.; Horisawa, M.; Hyyppä, J.; Yu, X.; Liang, X.; Wang, Y.

    2017-10-01

    Currently, the authors are planning to launch a consortium effort toward Japan's first smart precision forestry project using laser data and to develop this technology throughout the country. Smart precision forestry information gathered using the Nagano model (laser scanning from aircraft, drone, and backpack) is being developed to improve the sophistication of forest information, reduce labor-intensive work, maintain sustainable timber productivity, and facilitate supply chain management by laser sensing information in collaboration with industry, academia, and government. In this paper, we outline the research project and the technical development situation of unmanned aerial vehicle laser scanning.

  1. DEVELOPMENT OF SMART PRECISION FOREST IN CONIFER PLANTATION IN JAPAN USING LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    M. Katoh

    2017-10-01

    Full Text Available Currently, the authors are planning to launch a consortium effort toward Japan’s first smart precision forestry project using laser data and to develop this technology throughout the country. Smart precision forestry information gathered using the Nagano model (laser scanning from aircraft, drone, and backpack is being developed to improve the sophistication of forest information, reduce labor-intensive work, maintain sustainable timber productivity, and facilitate supply chain management by laser sensing information in collaboration with industry, academia, and government. In this paper, we outline the research project and the technical development situation of unmanned aerial vehicle laser scanning.

  2. Periodic and uniform nanogratings formed on cemented carbide by femtosecond laser scanning

    International Nuclear Information System (INIS)

    Lian, Yunsong; Deng, Jianxin; Xing, Youqiang; Lei, Shuting; Yu, Xiaoming

    2013-01-01

    Periodic and uniform nanogratings are fabricated by femtosecond laser scanning on cemented carbide. Specifically, three experiments are designed to study the influence of single pulse energy, scanning speed, and scanning spacing on the period and the uniformity of the formed nanogratings. The results show that the sample with single pulse energy of 2 μJ, scanning speed of 1000 μm/s, and scanning spacing of 5 μm shows the best quality of nanogratings among all the tested samples at different processing parameters. The uniformity of the nanogratings is largely determined by single pulse energy, scanning speed, and scanning spacing. Single pulse energy and scanning speed significantly affect the period of the nanogratings, whereas the period of the nanogratings maintains a fixed value under different scanning spacings. The period of the nanogratings increases gradually with the decrease of the single pulse energy and the increase of the scanning speed, respectively.

  3. Retinal Oximetry with Scanning Laser Ophthalmoscope in Infants.

    Directory of Open Access Journals (Sweden)

    Wouter B Vehmeijer

    Full Text Available Dual wavelength retinal oximetry has been developed for adults, but is not available for infants. Retinal oximetry may provide insight into the pathophysiology of oxygen-mediated diseases like retinopathy of prematurity. More insight in the oxygen metabolism of the retina in infants may provide valuable clues for better understanding and subsequent prevention or treatment of the disease. The measurements of oxygen saturation are obtained with two fundus images simultaneously captured in two different wavelengths of light. The comparison in light absorption of oxygenated and deoxygenated hemoglobin can be used to estimate the oxygen saturation within the retinal vessels by means of a software algorithm. This study aims to make retinal oximetry available for neonates. The first step towards estimating retinal oxygen saturation is determining the optical density ratio. Therefore, the purpose of this study is to image healthy newborn infants with a scanning laser ophthalmoscope and determine the optical density ratio for retinal oximetry analysis.Images of the retina of full-term healthy infants were obtained with an SLO, Optomap 200Tx (Optos, with two laser wavelengths (532nm and 633nm. The infant lay face down on the lower arm of the parent, while the parent supported the chest and chin with one hand, and stabilized the back with the other hand. No mydriatics or eyelid specula were used during this study. The images were analyzed with modified Oxymap Analyzer software for calculation of the Optical Density Ratio (ODR and vessel width. The ODR is inversely and approximately linearly related to the oxygen saturation. Measurements were included from the superotemporal vessel pair. A paired t-test was used for statistical analysis.Fifty-nine infants, (58% female, were included with mean gestational age of 40 ± 1.3 weeks (mean ± SD and mean post-natal age of 16 ± 4.8 days. A total of 28 images were selected for retinal oximetry analysis. The ODR was

  4. Clinical applications of in vivo fluorescence confocal laser scanning microscopy

    Science.gov (United States)

    Oh, Chilhwan; Park, Sangyong; Kim, Junhyung; Ha, Seunghan; Park, Gyuman; Lee, Gunwoo; Lee, Onseok; Chun, Byungseon; Gweon, Daegab

    2008-02-01

    Living skin for basic and clinical research can be evaluated by Confocal Laser Scanning Microscope (CLSM) non-invasively. CLSM imaging system can achieve skin image its native state either "in vivo" or "fresh biopsy (ex vivo)" without fixation, sectioning and staining that is necessary for routine histology. This study examines the potential fluorescent CLSM with a various exogenous fluorescent contrast agent, to provide with more resolution images in skin. In addition, in vivo fluorescent CLSM researchers will be extended a range of potential clinical application. The prototype of our CLSM system has been developed by Prof. Gweon's group. The operating parameters are composed of some units, such as illuminated wavelength 488 nm, argon illumination power up to 20mW on the skin, objective lens, 0.9NA oil immersion, axial resolution 1.0μm, field of view 200μm x 100μm (lateral resolution , 0.3μm). In human volunteer, fluorescein sodium was administrated topically and intradermally. Animal studies were done in GFP transgenic mouse, IRC mouse and pig skin. For imaging of animal skin, fluorescein sodium, acridine orange, and curcumine were used for fluorescein contrast agent. We also used the GFP transgenic mouse for fluorescein CLSM imaging. In intact skin, absorption of fluorescein sodium by individual corneocyte and hair. Intradermal administrated the fluorescein sodium, distinct outline of keratinocyte cell border could be seen. Curcumin is a yellow food dye that has similar fluorescent properties to fluorescein sodium. Acridin Orange can be highlight nuclei in viable keratinocyte. In vivo CLSM of transgenic GFP mouse enable on in vivo, high resolution view of GFP expressing skin tissue. GFP signals are brightest in corneocyte, kertinocyte, hair and eccrine gland. In intact skin, absorption of fluorescein sodium by individual corneocyte and hair. Intradermal administrated the fluorescein sodium, distinct outline of keratinocyte cell border could be seen. In

  5. Quantification of aggregate grain shape characteristics using 3-D laser scanning technology

    CSIR Research Space (South Africa)

    Mgangira, Martin B

    2013-07-01

    Full Text Available to identify the differences between individual aggregates. It was possible to quantify differences in particle shape characteristics at the small particle scale. The study has demonstrated the advantages of the innovative 3-D laser scanning technology...

  6. Three-dimensional laser scanning technique to quantify aggregate and ballast shape properties

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2013-06-01

    Full Text Available methods towards a more accurate and automated techniques to quantify aggregate shape properties. This paper validates a new flakiness index equation using three-dimensional (3-D) laser scanning data of aggregate and ballast materials obtained from...

  7. Visualization of carbon nanotubes dispersion in composite by using confocal laser scanning microscopy

    Czech Academy of Sciences Publication Activity Database

    Ilčíková, M.; Danko, M.; Doroshenko, M.; Best, A.; Mrlík, M.; Csomorová, K.; Šlouf, Miroslav; Chorvát Jr., D.; Koynov, K.; Mosnáček, J.

    2016-01-01

    Roč. 79, June (2016), s. 187-197 ISSN 0014-3057 Institutional support: RVO:61389013 Keywords : confocal laser scanning microscopy * composites * carbon nanotubes dispersion Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.531, year: 2016

  8. [Results of therapy of children with amblyopia by scanning stimulating laser].

    Science.gov (United States)

    Chentsova, O B; Magaramova, M D; Grechanyĭ, M P

    1997-01-01

    A new effective method for the treatment of amblyopia was used in 113 children: stimulation with ophthalmological SLSO-208A scanning laser by two methods differing by the transmission coefficient and scanning pattern. Good results were attained, the best when laser exposure was combined with traditional therapy for amblyopia and in the patients with the central fixation. The results were assessed by the main parameters of visual functions and the stability of the effect.

  9. Application of Mobile Laser Scanning for Lean and Rapid Highway Maintenance and Construction

    Science.gov (United States)

    2015-08-28

    Mobile Terrestrial Laser Scanning (MTLS) is an emerging technology that combines the use of a laser scanner(s), the Global Navigation Satellite System (GNSS), and an Inertial Measurement Unit (IMU) on a vehicle to collect geo-spatial data. The overal...

  10. An improved three-dimensional non-scanning laser imaging system based on digital micromirror device

    Science.gov (United States)

    Xia, Wenze; Han, Shaokun; Lei, Jieyu; Zhai, Yu; Timofeev, Alexander N.

    2018-01-01

    Nowadays, there are two main methods to realize three-dimensional non-scanning laser imaging detection, which are detection method based on APD and detection method based on Streak Tube. However, the detection method based on APD possesses some disadvantages, such as small number of pixels, big pixel interval and complex supporting circuit. The detection method based on Streak Tube possesses some disadvantages, such as big volume, bad reliability and high cost. In order to resolve the above questions, this paper proposes an improved three-dimensional non-scanning laser imaging system based on Digital Micromirror Device. In this imaging system, accurate control of laser beams and compact design of imaging structure are realized by several quarter-wave plates and a polarizing beam splitter. The remapping fiber optics is used to sample the image plane of receiving optical lens, and transform the image into line light resource, which can realize the non-scanning imaging principle. The Digital Micromirror Device is used to convert laser pulses from temporal domain to spatial domain. The CCD with strong sensitivity is used to detect the final reflected laser pulses. In this paper, we also use an algorithm which is used to simulate this improved laser imaging system. In the last, the simulated imaging experiment demonstrates that this improved laser imaging system can realize three-dimensional non-scanning laser imaging detection.

  11. Assessment of Relative Accuracy of AHN-2 Laser Scanning Data Using Planar Features

    NARCIS (Netherlands)

    Khoshelham, K.; Soudarissanane, S.; Van der Sande, C.

    2010-01-01

    AHN-2 is the second part of the Actueel Hoogtebestand Nederland project, which concerns the acquisition of high-resolution altimetry data over the entire Netherlands using airborne laser scanning. The accuracy assessment of laser altimetry data usually relies on comparing corresponding tie elements,

  12. Laser line scan underwater imaging by complementary metal-oxide-semiconductor camera

    Science.gov (United States)

    He, Zhiyi; Luo, Meixing; Song, Xiyu; Wang, Dundong; He, Ning

    2017-12-01

    This work employs the complementary metal-oxide-semiconductor (CMOS) camera to acquire images in a scanning manner for laser line scan (LLS) underwater imaging to alleviate backscatter impact of seawater. Two operating features of the CMOS camera, namely the region of interest (ROI) and rolling shutter, can be utilized to perform image scan without the difficulty of translating the receiver above the target as the traditional LLS imaging systems have. By the dynamically reconfigurable ROI of an industrial CMOS camera, we evenly divided the image into five subareas along the pixel rows and then scanned them by changing the ROI region automatically under the synchronous illumination by the fun beams of the lasers. Another scanning method was explored by the rolling shutter operation of the CMOS camera. The fun beam lasers were turned on/off to illuminate the narrow zones on the target in a good correspondence to the exposure lines during the rolling procedure of the camera's electronic shutter. The frame synchronization between the image scan and the laser beam sweep may be achieved by either the strobe lighting output pulse or the external triggering pulse of the industrial camera. Comparison between the scanning and nonscanning images shows that contrast of the underwater image can be improved by our LLS imaging techniques, with higher stability and feasibility than the mechanically controlled scanning method.

  13. Distance measurement using frequency scanning interferometry with mode-hoped laser

    Science.gov (United States)

    Medhat, M.; Sobee, M.; Hussein, H. M.; Terra, O.

    2016-06-01

    In this paper, frequency scanning interferometry is implemented to measure distances up to 5 m absolutely. The setup consists of a Michelson interferometer, an external cavity tunable diode laser, and an ultra-low expansion (ULE) Fabry-Pérot (FP) cavity to measure the frequency scanning range. The distance is measured by acquiring simultaneously the interference fringes from, the Michelson and the FP interferometers, while scanning the laser frequency. An online fringe processing technique is developed to calculate the distance from the fringe ratio while removing the parts result from the laser mode-hops without significantly affecting the measurement accuracy. This fringe processing method enables accurate distance measurements up to 5 m with measurements repeatability ±3.9×10-6 L. An accurate translation stage is used to find the FP cavity free-spectral-range and therefore allow accurate measurement. Finally, the setup is applied for the short distance calibration of a laser distance meter (LDM).

  14. 3D laser scanning in civil engineering - measurements of volume of earth masses

    Science.gov (United States)

    Pawłowicz, J. A.; Szafranko, E.; Harasymiuk, J.

    2018-03-01

    Considering the constant drive to improve and accelerate building processes as well as possible applications of the latest technological achievements in civil engineering practice, the author has proposed to use 3D laser scanning in the construction industry. For example, data achieved through a 3D laser scanning process will facilitate making inventories of parameters of buildings in a very short time, will enable one to check irregularly shaped masses of earth, heavy and practically impossible to calculate precisely using traditional techniques. The other part of the research, performed in the laboratory, consisted of measurements of a model mound of earth. All the measurements were made with a 3D SkanStation C10 laser scanner manufactured by Leica. The data were analyzed. The results suggest that there are great opportunities for using the laser scanning technology in civil engineering

  15. 3D Laser Scanning Assisted by Ordinary Plane Mirror for Non-direct Viewing Area

    Directory of Open Access Journals (Sweden)

    ZHANG Fan

    2017-12-01

    Full Text Available Terrestrial 3D laser scanning is one of principal methods to get the geometric information of object surface,and the integrity of the scanned object is a basic requirement in data acquisition. In order to solve the missing point cloud problem due to the scanning dead angle caused by confined working space,this paper proposes a method using ordinary plane mirror to obtain laser scanning data for non-direct viewing area according to the plane mirror reflection principle,analyzes the influence mechanism of the ordinary plane mirror on the propagation path and distance of laser beam,deduces the coordinate equation of the object point corresponding to the image point reflected by ordinary plane mirror in laser scanning. Given the laser scanning characteristic,this paper introduces a mirror reflection system included target balls and ordinary plane mirror,and expounds the system construction,system calibration and constructing method of system coordinate system. The feasibility and precision of the method are verified by experiments.

  16. Distribution and avoidance of debris on epoxy resin during UV ns-laser scanning processes

    Science.gov (United States)

    Veltrup, Markus; Lukasczyk, Thomas; Ihde, Jörg; Mayer, Bernd

    2018-05-01

    In this paper the distribution of debris generated by a nanosecond UV laser (248 nm) on epoxy resin and the prevention of the corresponding re-deposition effects by parameter selection for a ns-laser scanning process were investigated. In order to understand the mechanisms behind the debris generation, in-situ particle measurements were performed during laser treatment. These measurements enabled the determination of the ablation threshold of the epoxy resin as well as the particle density and size distribution in relation to the applied laser parameters. The experiments showed that it is possible to reduce debris on the surface with an adapted selection of pulse overlap with respect to laser fluence. A theoretical model for the parameter selection was developed and tested. Based on this model, the correct choice of laser parameters with reduced laser fluence resulted in a surface without any re-deposited micro-particles.

  17. A vision-based system for fast and accurate laser scanning in robot-assisted phonomicrosurgery.

    Science.gov (United States)

    Dagnino, Giulio; Mattos, Leonardo S; Caldwell, Darwin G

    2015-02-01

    Surgical quality in phonomicrosurgery can be improved by open-loop laser control (e.g., high-speed scanning capabilities) with a robust and accurate closed-loop visual servoing systems. A new vision-based system for laser scanning control during robot-assisted phonomicrosurgery was developed and tested. Laser scanning was accomplished with a dual control strategy, which adds a vision-based trajectory correction phase to a fast open-loop laser controller. The system is designed to eliminate open-loop aiming errors caused by system calibration limitations and by the unpredictable topology of real targets. Evaluation of the new system was performed using CO(2) laser cutting trials on artificial targets and ex-vivo tissue. This system produced accuracy values corresponding to pixel resolution even when smoke created by the laser-target interaction clutters the camera view. In realistic test scenarios, trajectory following RMS errors were reduced by almost 80 % with respect to open-loop system performances, reaching mean error values around 30 μ m and maximum observed errors in the order of 60 μ m. A new vision-based laser microsurgical control system was shown to be effective and promising with significant positive potential impact on the safety and quality of laser microsurgeries.

  18. IOT Overview Polarimetry

    Science.gov (United States)

    Ageorges, N.

    This contribution concentrates on the polarimetric modes offered by different instruments at ESO. In the introduction, I will demonstrate the importance of polarimetry, the kind of science it permits to achieve and list the instruments which offer these modes. Sects. 2 and 3 will present the involved modes in more details as well as the currently related calibrations, as part of the calibration plans.ESO does not offer any pure polarimetric instrument. As a consequence the polarimetric modes are just one (or more) mode(s) of the given instruments. Polarimetric modes might be mentioned in the related IOT but are not followed up thoroughly as is e.g. spectroscopy.

  19. Structural modification of silica glass by laser scanning

    International Nuclear Information System (INIS)

    Zhao Jian; Sullivan, James; Zayac, John; Bennett, Ted D.

    2004-01-01

    The thermophysical nature of rapid CO 2 laser heating of silica glass is explored using a numerical simulation that considers the structural state of the glass, as characterized by the fictive temperature. The fictive temperature reflects the thermodynamic temperature at which the glass structure would be in equilibrium. To demonstrate that the thermophysical model can accurately predict the structural change in the glass, the fictive temperature is measured experimentally utilizing the fact that the fictive temperature change corresponds to a change of glass properties that can be revealed through wet chemical etching. The relationship between the etch rate and the fictive temperature is determined by preparing and etching samples of known fictive temperature. Wet chemical etching is used to measure the fictive temperature over the entire laser affected zone and the results are found to compare favorably with the results of the thermophysical model. The model and experimental measurements demonstrate that rapid laser processing results in an increased fictive temperature near the surface of the glass. The fictive temperature increase is about 1000 K and is uniform to within 5% over the laser affected zone. Near the boundary of this zone, the fictive temperature transitions abruptly to the value of the surrounding untreated glass

  20. Unsynchronized scanning with a low-cost laser range finder for real-time range imaging

    Science.gov (United States)

    Hatipoglu, Isa; Nakhmani, Arie

    2017-06-01

    Range imaging plays an essential role in many fields: 3D modeling, robotics, heritage, agriculture, forestry, reverse engineering. One of the most popular range-measuring technologies is laser scanner due to its several advantages: long range, high precision, real-time measurement capabilities, and no dependence on lighting conditions. However, laser scanners are very costly. Their high cost prevents widespread use in applications. Due to the latest developments in technology, now, low-cost, reliable, faster, and light-weight 1D laser range finders (LRFs) are available. A low-cost 1D LRF with a scanning mechanism, providing the ability of laser beam steering for additional dimensions, enables to capture a depth map. In this work, we present an unsynchronized scanning with a low-cost LRF to decrease scanning period and reduce vibrations caused by stop-scan in synchronized scanning. Moreover, we developed an algorithm for alignment of unsynchronized raw data and proposed range image post-processing framework. The proposed technique enables to have a range imaging system for a fraction of the price of its counterparts. The results prove that the proposed method can fulfill the need for a low-cost laser scanning for range imaging for static environments because the most significant limitation of the method is the scanning period which is about 2 minutes for 55,000 range points (resolution of 250x220 image). In contrast, scanning the same image takes around 4 minutes in synchronized scanning. Once faster, longer range, and narrow beam LRFs are available, the methods proposed in this work can produce better results.

  1. The geometry of terrestrial laser scanning; identification of errors, modeling and mitigation of scanning geometry

    NARCIS (Netherlands)

    Soudarissanane, S.S.

    2016-01-01

    Over the past few decades, Terrestrial Laser Scanners are increasingly being used in a broad spectrum of applications, from surveying to civil engineering, medical modeling and forensics. Especially surveying applications require on one hand a quickly obtainable, high resolution point cloud but also

  2. High-efficient Nd:YAG microchip laser for optical surface scanning

    Science.gov (United States)

    Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

    2017-12-01

    A CW operating, compact, high-power, high-efficient diode pumped 1064nm laser, based on Nd:YAG active medium, was developed for optical surface scanning and mapping applications. To enhance the output beam quality, laser stability, and compactness, a microchip configuration was used. In this arrangement the resonator mirrors were deposited directly on to the laser crystal faces. The Nd-doping concentration was 1 at.% Nd/Y. The Nd:YAG crystal was 5mm long. The laser resonator without pumping radiation recuperation was investigated {the output coupler was transparent for pumping radiation. For the generated laser radiation the output coupler reflectivity was 95%@1064 nm. The diameter of the samples was 5 mm. For the laser pumping two arrangements were investigated. Firstly, a fibre coupled laser diode operating at wavelength 808nm was used in CW mode. The 400 ¹m fiber was delivering up to 14W of pump power amplitude to the microchip laser. The maximum CW output power of 7.2W @ 1064nm in close to TEM00 beam was obtained for incident pumping power 13.7W @ 808 nm. The differential efficiency in respect to the incident pump power reached 56 %. Secondly, a single-emitter, 1W laser diode operating at 808nm was used for Nd:YAG microchip pumping. The laser pumping was directly coupled into the microchip laser using free-space lens optics. Slope efficiency up to 70% was obtained in stable, high-quality, 1064nm laser beam with CW power up to 350mW. The system was successfully used for scanning of super-Gaussian laser mirrors reflectivity profile.

  3. Three-Dimensional Laser Scanning for Geometry Documentation and Construction Management of Highway Tunnels during Excavation

    Science.gov (United States)

    Gikas, Vassilis

    2012-01-01

    Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered. PMID:23112655

  4. Recommendations for the design and the installation of large laser scanning microscopy systems

    Science.gov (United States)

    Helm, P. Johannes

    2012-03-01

    Laser Scanning Microscopy (LSM) has since the inventions of the Confocal Scanning Laser Microscope (CLSM) and the Multi Photon Laser Scanning Microscope (MPLSM) developed into an essential tool in contemporary life science and material science. The market provides an increasing number of turn-key and hands-off commercial LSM systems, un-problematic to purchase, set up and integrate even into minor research groups. However, the successful definition, financing, acquisition, installation and effective use of one or more large laser scanning microscopy systems, possibly of core facility character, often requires major efforts by senior staff members of large academic or industrial units. Here, a set of recommendations is presented, which are helpful during the process of establishing large systems for confocal or non-linear laser scanning microscopy as an effective operational resource in the scientific or industrial production process. Besides the description of technical difficulties and possible pitfalls, the article also illuminates some seemingly "less scientific" processes, i.e. the definition of specific laboratory demands, advertisement of the intention to purchase one or more large systems, evaluation of quotations, establishment of contracts and preparation of the local environment and laboratory infrastructure.

  5. SOME ASPECTS OF SCANNING LASER OPHTHALMOSCOPY IN THE DIAGNOSTICS OF OPHTHALMOPATHOLOGY

    Directory of Open Access Journals (Sweden)

    S. A. Kochergin

    2017-01-01

    Full Text Available The exact diagnosis of the fundus pathology requires the most modern equipment use. This is mandatory for the selection of the most complete therapy and monitoring of ongoing treatment. At present, the method of scanning laser ophthalmoscopy is widely spread. However, for the earliest detection of the smallest pathological changes, data of the normal ocular fundus state using a scanning laser ophthalmoscope is necessary. Thus, the purpose of our research becomes relevant. Purpose: to give a characteristic of the fundus in patients without concomitant pathology with using various modes of a scanning laser ophthalmoscope. Patients and methods. 116 people (232 eyes at the age from 17 to 71 years (mean age 32.5±12 years were examined. The patients were divided into two groups. Group I: 81 patients (162 eyes with different ophthalmopathology. Group II: 35 people (70 eyes — practically healthy and did not have an anamnesis of consulting an ophthalmologist. Diagnosis of the patients’ fundus was performed using a scanning laser ophthalmoscopy with retro-mode imaging and autofluorescence registration. Results. After the conducted research features and regularities of the reflectivity distribution of laser beams from the fundus structures are revealed. Also a characteristic of various anatomical formations and zones of the fundus in the normal conditions is given when examined by a scanning laser ophthalmoscope. An algorithm for examining patients and analyzing the images was developed. Conclusion. The use of scanning laser ophthalmoscopy made possible to take a fresh look at the algorithms of diagnosing patients with fundus pathology. Understanding the normal conditions ofundus allowed an earlier detection of the smallest pathological changes in the retina. 

  6. Experimental validation of a newly designed 6 degrees of freedom scanning laser head: Application to three-dimensional beam structure

    International Nuclear Information System (INIS)

    Di Maio, D.; Copertaro, E.

    2013-01-01

    A new scanning laser head is designed to use single Laser Doppler Vibrometer (LDV) for performing measurements up to 6 degrees of freedom (DOF) at a target. The scanning head is supported by a rotating hollow shaft, which allows the laser beam to travel up to the scanning head from an opposite direction where an LDV is set up. The scanning head is made of a set of two mirrors, which deflects the laser beam with an angle so that the rotation of the scanning head produces a conical scan. When measurements are performed at the focal point of the conical scan then three translational vibration components can be measured, otherwise the very small circle scan, before and after the focal point, can measure up to 6 degrees of freedom, including three translations and three rotations. This paper presents the 6DOF scanning head and the measurements of 3D operational deflection shapes of a test structure

  7. High-frequency fluctuation measurements by far-infrared laser Faraday-effect polarimetry-interferometry and forward scattering system on MST.

    Science.gov (United States)

    Ding, W X; Lin, L; Duff, J R; Brower, D L

    2014-11-01

    Magnetic fluctuation-induced transport driven by global tearing modes has been measured by Faraday-effect polarimetry and interferometry (phase measurements) in the MST reversed field pinch. However, the role of small-scale broadband magnetic and density turbulence in transport remains unknown. In order to investigate broadband magnetic turbulence, we plan to upgrade the existing detector system by using planar-diode fundamental waveguide mixers optimized for high sensitivity. Initial tests indicate these mixers have ×10 sensitivity improvement compared to currently employed corner-cube Schottky-diode mixers and ×5 lower noise. Compact mixer design will allow us to resolve the wavenumbers up to k ∼ 1-2 cm(-1) for beam width w = 1.5 cm and 15 cm(-1) for beam width w = 2 mm. The system can also be used to measure the scattered signal (amplitude measurement) induced by both plasma density and magnetic fluctuations.

  8. Slope excavation quality assessment and excavated volume calculation in hydraulic projects based on laser scanning technology

    Directory of Open Access Journals (Sweden)

    Chao Hu

    2015-04-01

    Full Text Available Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak, cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laser-scanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation quality assessment with the laser scanning technology can be reduced by 70%–90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.

  9. Towards Robust Self-Calibration for Handheld 3d Line Laser Scanning

    Science.gov (United States)

    Bleier, M.; Nüchter, A.

    2017-11-01

    This paper studies self-calibration of a structured light system, which reconstructs 3D information using video from a static consumer camera and a handheld cross line laser projector. Intersections between the individual laser curves and geometric constraints on the relative position of the laser planes are exploited to achieve dense 3D reconstruction. This is possible without any prior knowledge of the movement of the projector. However, inaccurrately extracted laser lines introduce noise in the detected intersection positions and therefore distort the reconstruction result. Furthermore, when scanning objects with specular reflections, such as glossy painted or metalic surfaces, the reflections are often extracted from the camera image as erroneous laser curves. In this paper we investiagte how robust estimates of the parameters of the laser planes can be obtained despite of noisy detections.

  10. Cellular scanning strategy for selective laser melting: Generating reliable, optimized scanning paths and processing parameters

    DEFF Research Database (Denmark)

    Mohanty, Sankhya; Hattel, Jesper Henri

    2015-01-01

    method based uncertainty and reliability analysis. The reliability of the scanning paths are established using cumulative probability distribution functions for process output criteria such as sample density, thermal homogeneity, etc. A customized genetic algorithm is used along with the simulation model...

  11. Functional and ophthalmoscopic observations in human laser accident cases using scanning-laser ophthalmoscopy

    Science.gov (United States)

    Zwick, Harry; Lund, David J.; Gagliano, Donald A.; Stuck, Bruce E.

    1994-06-01

    A scanning laser ophthalmoscope (SLO) equipped with an acousto- optical modulator (ACM) was used to make focal acuity and contrast sensitivity measurements in individuals with macular damage. The depth of modulation achieved by the ACM was determined by imaging the SLO raster pattern onto a Pulnix TM 745 video camera and evaluating the intensity distribution with a Big Sky BVA10 beam view analyzer. Contrast levels remained approximately constant over the entire range of SLO input raster power settings. A delta Technologies image processing system produced Landolt ring test stimuli at the center of the raster pattern. Contrast thresholds were determined at various retinal locations by having subjects fixate a specific location on a fixed grid imaged on the raster pattern. This procedure insured that the test stimuli were always imaged in the center of the raster pattern thereby avoiding peripheral variations in the raster pattern intensity distribution. Measurements of contrast sensitivity where focal test targets fell within the macular damage area demonstrated elevated contrast thresholds relative to retinal locations where focal test targets evaluated the border regions between normal and pathological retina.

  12. Scanning vs. single spot laser ablation (λ=213 nm) inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Gonzalez, Jhanis J.; Fernandez, Alberto; Mao Xianglei; Russo, Richard E.

    2004-01-01

    Sampling strategy is defined in this work as the interaction of a repetitively pulsed laser beam with a fixed position on a sample (single spot) or with a moving sample (scan). Analytical performance of these sampling strategies was compared by using 213 nm laser ablation ICP-MS. A geological rock (Tuff) was quantitatively analyzed based on NIST series 610-616 glass standard reference materials. Laser ablation data were compared to ICP-MS analysis of the dissolved samples. The scan strategy (50 μm/s) produced a flat, steady temporal ICP-MS response whereas the single spot strategy produced a signal that decayed with time (after 60 s). Single-spot sampling provided better accuracy and precision than the scan strategy when the first 15 s of the sampling time was eliminated from the data analysis. In addition, the single spot strategy showed less matrix dependence among the four NIST glasses

  13. Il laser scanning e CloudCUBE per le grotte di Naica

    Directory of Open Access Journals (Sweden)

    Erminio Paolo Canevese

    2008-03-01

    Full Text Available Laser scanning and CloudCube for Naica caves On May 2007, Virtualgeo, a geomatic software development and communication company, took part in the first official expedition to Mexico. The Project, coined "Naica", involves researchers from ten universities, four companies and several laboratories. Virtualgeo carried out the survey by applying laser scanning technology to hypogeal caves covered with selenite crystals. The data was processed using CloudCUBE, a proprietary software designed to manage and model 3D point clouds. The first results of the laser scanning survey of a spectacular “forest of crystals” are presented here.

  14. Il laser scanning e CloudCUBE per le grotte di Naica

    Directory of Open Access Journals (Sweden)

    Erminio Paolo Canevese

    2008-03-01

    Full Text Available Laser scanning and CloudCube for Naica cavesOn May 2007, Virtualgeo, a geomatic software development and communication company, took part in the first official expedition to Mexico. The Project, coined "Naica", involves researchers from ten universities, four companies and several laboratories. Virtualgeo carried out the survey by applying laser scanning technology to hypogeal caves covered with selenite crystals. The data was processed using CloudCUBE, a proprietary software designed to manage and model 3D point clouds. The first results of the laser scanning survey of a spectacular “forest of crystals” are presented here.

  15. Rapid Prototyping — A Tool for Presenting 3-Dimensional Digital Models Produced by Terrestrial Laser Scanning

    Directory of Open Access Journals (Sweden)

    Juho-Pekka Virtanen

    2014-07-01

    Full Text Available Rapid prototyping has received considerable interest with the introduction of affordable rapid prototyping machines. These machines can be used to manufacture physical models from three-dimensional digital mesh models. In this paper, we compare the results obtained with a new, affordable, rapid prototyping machine, and a traditional professional machine. Two separate data sets are used for this, both of which were acquired using terrestrial laser scanning. Both of the machines were able to produce complex and highly detailed geometries in plastic material from models based on terrestrial laser scanning. The dimensional accuracies and detail levels of the machines were comparable, and the physical artifacts caused by the fused deposition modeling (FDM technique used in the rapid prototyping machines could be found in both models. The accuracy of terrestrial laser scanning exceeded the requirements for manufacturing physical models of large statues and building segments at a 1:40 scale.

  16. A multiphoton laser scanning microscope setup for transcranial in vivo brain imaging on mice

    Science.gov (United States)

    Nase, Gabriele; Helm, P. Johannes; Reppen, Trond; Ottersen, Ole Petter

    2005-12-01

    We describe a multiphoton laser scanning microscope setup for transcranial in vivo brain imaging in mice. The modular system is based on a modified industrial standard Confocal Scanning Laser Microscope (CSLM) and is assembled mainly from commercially available components. A special multifunctional stage, which is optimized for both laser scanning microscopic observation and preparative animal surgery, has been developed and built. The detection unit includes a highly efficient photomultiplier tube installed in a Peltier-cooled thermal box shielding the detector from changes in room temperature and from distortions caused by external electromagnetic fields. The images are recorded using a 12-bit analog-to-digital converter. Depending on the characteristics of the staining, individual nerve cells can be imaged down to at least 100μm below the intact cranium and down to at least 200μm below the opened cranium.

  17. Laser scanning confocal microscope with programmable amplitude, phase, and polarization of the illumination beam.

    Science.gov (United States)

    Boruah, B R; Neil, M A A

    2009-01-01

    We describe the design and construction of a laser scanning confocal microscope with programmable beam forming optics. The amplitude, phase, and polarization of the laser beam used in the microscope can be controlled in real time with the help of a liquid crystal spatial light modulator, acting as a computer generated hologram, in conjunction with a polarizing beam splitter and two right angled prisms assembly. Two scan mirrors, comprising an on-axis fast moving scan mirror for line scanning and an off-axis slow moving scan mirror for frame scanning, configured in a way to minimize the movement of the scanned beam over the pupil plane of the microscope objective, form the XY scan unit. The confocal system, that incorporates the programmable beam forming unit and the scan unit, has been implemented to image in both reflected and fluorescence light from the specimen. Efficiency of the system to programmably generate custom defined vector beams has been demonstrated by generating a bottle structured focal volume, which in fact is the overlap of two cross polarized beams, that can simultaneously improve both the lateral and axial resolutions if used as the de-excitation beam in a stimulated emission depletion confocal microscope.

  18. Automatic concrete cracks detection and mapping of terrestrial laser scan data

    Directory of Open Access Journals (Sweden)

    Mostafa Rabah

    2013-12-01

    The current paper submits a method for automatic concrete cracks detection and mapping from the data that was obtained during laser scanning survey. The method of cracks detection and mapping is achieved by three steps, namely the step of shading correction in the original image, step of crack detection and finally step of crack mapping and processing steps. The detected crack is defined in a pixel coordinate system. To remap the crack into the referred coordinate system, a reverse engineering is used. This is achieved by a hybrid concept of terrestrial laser-scanner point clouds and the corresponding camera image, i.e. a conversion from the pixel coordinate system to the terrestrial laser-scanner or global coordinate system. The results of the experiment show that the mean differences between terrestrial laser scan and the total station are about 30.5, 16.4 and 14.3 mms in x, y and z direction, respectively.

  19. Graph Structure-Based Simultaneous Localization and Mapping Using a Hybrid Method of 2D Laser Scan and Monocular Camera Image in Environments with Laser Scan Ambiguity

    Directory of Open Access Journals (Sweden)

    Taekjun Oh

    2015-07-01

    Full Text Available Localization is an essential issue for robot navigation, allowing the robot to perform tasks autonomously. However, in environments with laser scan ambiguity, such as long corridors, the conventional SLAM (simultaneous localization and mapping algorithms exploiting a laser scanner may not estimate the robot pose robustly. To resolve this problem, we propose a novel localization approach based on a hybrid method incorporating a 2D laser scanner and a monocular camera in the framework of a graph structure-based SLAM. 3D coordinates of image feature points are acquired through the hybrid method, with the assumption that the wall is normal to the ground and vertically flat. However, this assumption can be relieved, because the subsequent feature matching process rejects the outliers on an inclined or non-flat wall. Through graph optimization with constraints generated by the hybrid method, the final robot pose is estimated. To verify the effectiveness of the proposed method, real experiments were conducted in an indoor environment with a long corridor. The experimental results were compared with those of the conventional GMappingapproach. The results demonstrate that it is possible to localize the robot in environments with laser scan ambiguity in real time, and the performance of the proposed method is superior to that of the conventional approach.

  20. Centimeter-scale MEMS scanning mirrors for high power laser application

    Science.gov (United States)

    Senger, F.; Hofmann, U.; v. Wantoch, T.; Mallas, C.; Janes, J.; Benecke, W.; Herwig, Patrick; Gawlitza, P.; Ortega-Delgado, M.; Grune, C.; Hannweber, J.; Wetzig, A.

    2015-02-01

    A higher achievable scan speed and the capability to integrate two scan axes in a very compact device are fundamental advantages of MEMS scanning mirrors over conventional galvanometric scanners. There is a growing demand for biaxial high speed scanning systems complementing the rapid progress of high power lasers for enabling the development of new high throughput manufacturing processes. This paper presents concept, design, fabrication and test of biaxial large aperture MEMS scanning mirrors (LAMM) with aperture sizes up to 20 mm for use in high-power laser applications. To keep static and dynamic deformation of the mirror acceptably low all MEMS mirrors exhibit full substrate thickness of 725 μm. The LAMM-scanners are being vacuum packaged on wafer-level based on a stack of 4 wafers. Scanners with aperture sizes up to 12 mm are designed as a 4-DOF-oscillator with amplitude magnification applying electrostatic actuation for driving a motor-frame. As an example a 7-mm-scanner is presented that achieves an optical scan angle of 32 degrees at 3.2 kHz. LAMM-scanners with apertures sizes of 20 mm are designed as passive high-Q-resonators to be externally excited by low-cost electromagnetic or piezoelectric drives. Multi-layer dielectric coatings with a reflectivity higher than 99.9 % have enabled to apply cw-laser power loads of more than 600 W without damaging the MEMS mirror. Finally, a new excitation concept for resonant scanners is presented providing advantageous shaping of intensity profiles of projected laser patterns without modulating the laser. This is of interest in lighting applications such as automotive laser headlights.

  1. [Application Progress of Three-dimensional Laser Scanning Technology in Medical Surface Mapping].

    Science.gov (United States)

    Zhang, Yonghong; Hou, He; Han, Yuchuan; Wang, Ning; Zhang, Ying; Zhu, Xianfeng; Wang, Mingshi

    2016-04-01

    The booming three-dimensional laser scanning technology can efficiently and effectively get spatial three-dimensional coordinates of the detected object surface and reconstruct the image at high speed,high precision and large capacity of information.Non-radiation,non-contact and the ability of visualization make it increasingly popular in three-dimensional surface medical mapping.This paper reviews the applications and developments of three-dimensional laser scanning technology in medical field,especially in stomatology,plastic surgery and orthopedics.Furthermore,the paper also discusses the application prospects in the future as well as the biomedical engineering problems it would encounter with.

  2. D Model of AL Zubarah Fortress in Qatar - Terrestrial Laser Scanning VS. Dense Image Matching

    Science.gov (United States)

    Kersten, T.; Mechelke, K.; Maziull, L.

    2015-02-01

    In September 2011 the fortress Al Zubarah, built in 1938 as a typical Arabic fortress and restored in 1987 as a museum, was recorded by the HafenCity University Hamburg using terrestrial laser scanning with the IMAGER 5006h and digital photogrammetry for the Qatar Museum Authority within the framework of the Qatar Islamic Archaeology and Heritage Project. One goal of the object recording was to provide detailed 2D/3D documentation of the fortress. This was used to complete specific detailed restoration work in the recent years. From the registered laser scanning point clouds several cuttings and 2D plans were generated as well as a 3D surface model by triangle meshing. Additionally, point clouds and surface models were automatically generated from digital imagery from a Nikon D70 using the open-source software Bundler/PMVS2, free software VisualSFM, Autodesk Web Service 123D Catch beta, and low-cost software Agisoft PhotoScan. These outputs were compared with the results from terrestrial laser scanning. The point clouds and surface models derived from imagery could not achieve the same quality of geometrical accuracy as laser scanning (i.e. 1-2 cm).

  3. MULTISPECTRAL AIRBORNE LASER SCANNING - A NEW TREND IN THE DEVELOPMENT OF LIDAR TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Bakuła Krzysztof

    2015-12-01

    Full Text Available Airborne laser scanning (ALS is the one of the most accurate remote sensing techniques for data acquisition where the terrain and its coverage is concerned. Modern scanners have been able to scan in two or more channels (frequencies of the laser recently. This gives the rise to the possibility of obtaining diverse information about an area with the different spectral properties of objects. The paper presents an example of a multispectral ALS system - Titan by Optech - with the possibility of data including the analysis of digital elevation models accuracy and data density. As a result of the study, the high relative accuracy of LiDAR acquisition in three spectral bands was proven. The mean differences between digital terrain models (DTMs were less than 0.03 m. The data density analysis showed the influence of the laser wavelength. The points clouds that were tested had average densities of 25, 23 and 20 points per square metre respectively for green (G, near-infrared (NIR and shortwave-infrared (SWIR lasers. In this paper, the possibility of the generation of colour composites using orthoimages of laser intensity reflectance and its classification capabilities using data from airborne multispectral laser scanning for land cover mapping are also discussed and compared with conventional photogrammetric techniques.

  4. A flexible 3D laser scanning system using a robotic arm

    Science.gov (United States)

    Fei, Zixuan; Zhou, Xiang; Gao, Xiaofei; Zhang, Guanliang

    2017-06-01

    In this paper, we present a flexible 3D scanning system based on a MEMS scanner mounted on an industrial arm with a turntable. This system has 7-degrees of freedom and is able to conduct a full field scan from any angle, suitable for scanning object with the complex shape. The existing non-contact 3D scanning system usually uses laser scanner that projects fixed stripe mounted on the Coordinate Measuring Machine (CMM) or industrial robot. These existing systems can't perform path planning without CAD models. The 3D scanning system presented in this paper can scan the object without CAD models, and we introduced this path planning method in the paper. We also propose a practical approach to calibrating the hand-in-eye system based on binocular stereo vision and analyzes the errors of the hand-eye calibration.

  5. Polarimetry diagnostic on OMEGA EP using a 10-ps, 263-nm probe beam

    International Nuclear Information System (INIS)

    Davies, A.; Haberberger, D.; Boni, R.; Ivancic, S.; Brown, R.; Froula, D. H.

    2014-01-01

    A polarimetry diagnostic was built and characterized for magnetic-field measurements in laser-plasma experiments on the OMEGA EP laser. This diagnostic was built into the existing 4ω (263-nm) probe system that employs a 10-ps laser pulse collected with an f/4 imaging system. The diagnostic measures the rotation of the probe beam's polarization. The polarimeter uses a Wollaston prism to split the probe beam into orthogonal polarization components. Spatially localized intensity variations between images indicate polarization rotation. Magnetic fields can be calculated by combining the polarimetry data with the measured plasma density profile obtained from angular filter refractometry

  6. Polarimetry diagnostic on OMEGA EP using a 10-ps, 263-nm probe beam.

    Science.gov (United States)

    Davies, A; Haberberger, D; Boni, R; Ivancic, S; Brown, R; Froula, D H

    2014-11-01

    A polarimetry diagnostic was built and characterized for magnetic-field measurements in laser-plasma experiments on the OMEGA EP laser. This diagnostic was built into the existing 4ω (263-nm) probe system that employs a 10-ps laser pulse collected with an f/4 imaging system. The diagnostic measures the rotation of the probe beam's polarization. The polarimeter uses a Wollaston prism to split the probe beam into orthogonal polarization components. Spatially localized intensity variations between images indicate polarization rotation. Magnetic fields can be calculated by combining the polarimetry data with the measured plasma density profile obtained from angular filter refractometry.

  7. Polarimetry diagnostic on OMEGA EP using a 10-ps, 263-nm probe beam

    Energy Technology Data Exchange (ETDEWEB)

    Davies, A., E-mail: adavies@lle.rochester.edu; Haberberger, D.; Boni, R.; Ivancic, S.; Brown, R.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

    2014-11-15

    A polarimetry diagnostic was built and characterized for magnetic-field measurements in laser-plasma experiments on the OMEGA EP laser. This diagnostic was built into the existing 4ω (263-nm) probe system that employs a 10-ps laser pulse collected with an f/4 imaging system. The diagnostic measures the rotation of the probe beam's polarization. The polarimeter uses a Wollaston prism to split the probe beam into orthogonal polarization components. Spatially localized intensity variations between images indicate polarization rotation. Magnetic fields can be calculated by combining the polarimetry data with the measured plasma density profile obtained from angular filter refractometry.

  8. Characterization of photonic structures using visible and infrared polarimetry

    Directory of Open Access Journals (Sweden)

    Kral Z.

    2010-06-01

    Full Text Available Photonic Crystals are materials with a spatial periodic variation of the refractive index on the wavelength scale. This confers these materials interesting photonic properties such as the existence of photonic bands and forbidden photon frequency ranges, the photonic band gaps. Among their applications it is worth mentioning the achievement of low-threshold lasers and high-Q resonant cavities. A particular case of the Photonic Crystals is well-known and widely studied since a long time: the periodic thin film coatings. The characterization of thin film coatings is a classical field of study with a very well established knowledge. However, characterization of 2D and 3D photonic crystals needs to be studied in detail as it poses new problems that have to be solved. In this sense, Polarimetry is a specially suited tool given their inherent anisotropy: photonic bands depend strongly on the propagation direction and on polarization. In this work we show how photonic crystal structures can be characterized using polarimetry equipment. We compare the numerical modeling of the interaction of the light polarization with the photonic crystal with the polarimetry measurements. With the S-Matrix formalism, the Mueller matrix of a Photonic Crystal for a given wavelength, angle of incidence and propagation direction can be obtained. We will show that useful information from polarimetry (and also from spectrometry can be obtained when multivariate spectra are considered. We will also compare the simulation results with Polarimetry measurements on different kinds of samples: macroporous silicon photonic crystals in the near-IR range and Laser-Interference-Lithography nanostructured photoresist.

  9. Remote defect imaging for plate-like structures based on the scanning laser source technique

    Science.gov (United States)

    Hayashi, Takahiro; Maeda, Atsuya; Nakao, Shogo

    2018-04-01

    In defect imaging with a scanning laser source technique, the use of a fixed receiver realizes stable measurements of flexural waves generated by laser at multiple rastering points. This study discussed the defect imaging by remote measurements using a laser Doppler vibrometer as a receiver. Narrow-band burst waves were generated by modulating laser pulse trains of a fiber laser to enhance signal to noise ratio in frequency domain. Averaging three images obtained at three different frequencies suppressed spurious distributions due to resonance. The experimental system equipped with these newly-devised means enabled us to visualize defects and adhesive objects in plate-like structures such as a plate with complex geometries and a branch pipe.

  10. Validation of a new noniterative method for accurate position determination of a scanning laser vibrometer

    Science.gov (United States)

    Pauwels, Steven; Boucart, Nick; Dierckx, Benoit; Van Vlierberghe, Pieter

    2000-05-01

    The use of a scanning laser Doppler vibrometer for vibration testing is becoming a popular instrument. The scanning laser Doppler vibrometer is a non-contacting transducer that can measure many points at a high spatial resolution in a short time. Manually aiming the laser beam at the points that need to be measured is very time consuming. In order to use it effectively, the position of the laser Doppler vibrometer needs to be determined relative to the structure. If the position of the laser Doppler vibrometer is known, any visible point on the structure can be hit and measured automatically. A new algorithm for this position determination is developed, based on a geometry model of the structure. After manually aiming the laser beam at 4 or more known points, the laser position and orientation relative to the structure is determined. Using this calculated position and orientation a list with the mirror angles for every measurement point is generated, which is used during the measurement. The algorithm is validated using 3 practical cases. In the first case a plate is used of which the points are measured very accurately, so the geometry model is assumed to be perfect. The second case is a brake disc. Here the geometry points are measured with a ruler, thus not so accurate. The final validation is done on a body in white of a car. A reduced finite element model is used as geometry model. This calibration shows that the new algorithm is very effective and practically usable.

  11. Efficient green lasers for high-resolution scanning micro-projector displays

    Science.gov (United States)

    Bhatia, Vikram; Bauco, Anthony S.; Oubei, Hassan M.; Loeber, David A. S.

    2010-02-01

    Laser-based projectors are gaining increased acceptance in mobile device market due to their low power consumption, superior image quality and small size. The basic configuration of such micro-projectors is a miniature mirror that creates an image by raster scanning the collinear red, blue and green laser beams that are individually modulated on a pixel-bypixel basis. The image resolution of these displays can be limited by the modulation bandwidth of the laser sources, and the modulation speed of the green laser has been one of the key limitations in the development of these displays. We will discuss how this limitation is fundamental to the architecture of many laser designs and then present a green laser configuration which overcomes these difficulties. In this green laser architecture infra-red light from a distributed Bragg-reflector (DBR) laser diode undergoes conversion to green light in a waveguided second harmonic generator (SHG) crystal. The direct doubling in a single pass through the SHG crystal allows the device to operate at the large modulation bandwidth of the DBR laser. We demonstrate that the resultant product has a small footprint (9% electrical-to-optical conversion) and large modulation bandwidth (>100 MHz).

  12. Topographic laser ranging and scanning principles and processing

    CERN Document Server

    Shan, Jie

    2008-01-01

    A systematic, in-depth introduction to theories and principles of Light Detection and Ranging (LiDAR) technology is long overdue, as it is the most important geospatial data acquisition technology to be introduced in recent years. An advanced discussion, this text fills the void.Professionals in fields ranging from geology, geography and geoinformatics to physics, transportation, and law enforcement will benefit from this comprehensive discussion of topographic LiDAR principles, systems, data acquisition, and data processing techniques. The book covers ranging and scanning fundamentals, and broad, contemporary analysis of airborne LiDAR systems, as well as those situated on land and in space. The authors present data collection at the signal level in terms of waveforms and their properties; at the system level with regard to calibration and georeferencing; and at the data level to discuss error budget, quality control, and data organization. They devote the bulk of the book to LiDAR data processing and inform...

  13. Two-photon excitation laser scanning microscopy of rabbit nasal septal cartilage following Nd:YAG-laser-mediated stress relaxation

    Science.gov (United States)

    Kim, Charlton C.; Wallace, Vincent P.; Coleno, Mariah L.; Dao, Xavier; Tromberg, Bruce J.; Wong, Brian J.

    2000-04-01

    Laser irradiation of hyaline cartilage result in stable shape changes due to temperature dependent stress relaxation. In this study, we determined the structural changes in chondrocytes within rabbit nasal septal cartilage tissue over a 12-day period using a two-photon laser scanning microscope (TPM) following Nd:YAG laser irradiation. During laser irradiation surface temperature, stress relaxation, and diffuse reflectance, were measured dynamically. Each specimen received one or two sequential laser exposures. The cartilage reached a peak surface temperature of about 61 degrees C during irradiation. Cartilage denatured in 50 percent EtOH was used as a positive control. TPM was performed to detect the fluorescence emission from the chondrocytes. Images of chondrocytes were obtained at depths up to 150 microns, immediately following laser exposure, and also following 12 days in culture. Few differences in the pattern or intensity of fluorescence was observed between controls and irradiated specimens imaged immediately following exposure, regardless of the number of laser pulses. However, following twelve days in tissue culture, the irradiated specimens increase, whereas the native tissue diminishes, in intensity and distribution of fluorescence in the cytoplasm. In contrast, the positive control shows only extracellular matrices and empty lacuna, feature consistent with cell membrane lysis.

  14. Fan-beam scanning laser optical computed tomography for large volume dosimetry

    Science.gov (United States)

    Dekker, K. H.; Battista, J. J.; Jordan, K. J.

    2017-05-01

    A prototype scanning-laser fan beam optical CT scanner is reported which is capable of high resolution, large volume dosimetry with reasonable scan time. An acylindrical, asymmetric aquarium design is presented which serves to 1) generate parallel-beam scan geometry, 2) focus light towards a small acceptance angle detector, and 3) avoid interference fringe-related artifacts. Preliminary experiments with uniform solution phantoms (11 and 15 cm diameter) and finger phantoms (13.5 mm diameter FEP tubing) demonstrate that the design allows accurate optical CT imaging, with optical CT measurements agreeing within 3% of independent Beer-Lambert law calculations.

  15. Fan-beam scanning laser optical computed tomography for large volume dosimetry

    International Nuclear Information System (INIS)

    Dekker, K H; Battista, J J; Jordan, K J

    2017-01-01

    A prototype scanning-laser fan beam optical CT scanner is reported which is capable of high resolution, large volume dosimetry with reasonable scan time. An acylindrical, asymmetric aquarium design is presented which serves to 1) generate parallel-beam scan geometry, 2) focus light towards a small acceptance angle detector, and 3) avoid interference fringe-related artifacts. Preliminary experiments with uniform solution phantoms (11 and 15 cm diameter) and finger phantoms (13.5 mm diameter FEP tubing) demonstrate that the design allows accurate optical CT imaging, with optical CT measurements agreeing within 3% of independent Beer-Lambert law calculations. (paper)

  16. Glacier Snowline Determination from Terrestrial Laser Scanning Intensity Data

    Directory of Open Access Journals (Sweden)

    Hannah Prantl

    2017-07-01

    Full Text Available Accurately identifying the extent of surface snow cover on glaciers is important for extrapolating end of year mass balance measurements, constraining the glacier surface radiative energy balance and evaluating model simulations of snow cover. Here, we use auxiliary information from Riegl VZ-6000 Terrestrial Laser Scanner (TLS return signals to accurately map the snow cover over a glacier throughout an ablation season. Three classification systems were compared, and we find that supervised classification based on TLS signal intensity alone is outperformed by a rule-based classification employing intensity, surface roughness and an associated optical image, which achieves classification accuracy of 68–100%. The TLS intensity signal shows no meaningful relationship with surface or bulk snow density. Finally, we have also compared our Snow Line Altitude (SLA derived from TLS with SLA derived from the model output, as well as one Landsat image. The results of the model output track the SLA from TLS well, however with a positive bias. In contrast, automatic Landsat-derived SLA slightly underestimates the SLA from TLS. To conclude, we demonstrate that the snow cover extent can be mapped successfully using TLS, although the snow mass remains elusive.

  17. Application of 3D Laser Scanning Technology in Complex Rock Foundation Design

    Science.gov (United States)

    Junjie, Ma; Dan, Lu; Zhilong, Liu

    2017-12-01

    Taking the complex landform of Tanxi Mountain Landscape Bridge as an example, the application of 3D laser scanning technology in the mapping of complex rock foundations is studied in this paper. A set of 3D laser scanning technologies are formed and several key engineering problems are solved. The first is 3D laser scanning technology of complex landforms. 3D laser scanning technology is used to obtain a complete 3D point cloud data model of the complex landform. The detailed and accurate results of the surveying and mapping decrease the measuring time and supplementary measuring times. The second is 3D collaborative modeling of the complex landform. A 3D model of the complex landform is established based on the 3D point cloud data model. The super-structural foundation model is introduced for 3D collaborative design. The optimal design plan is selected and the construction progress is accelerated. And the last is finite-element analysis technology of the complex landform foundation. A 3D model of the complex landform is introduced into ANSYS for building a finite element model to calculate anti-slide stability of the rock, and provides a basis for the landform foundation design and construction.

  18. Real-time depth monitoring and control of laser machining through scanning beam delivery system

    International Nuclear Information System (INIS)

    Ji, Yang; Grindal, Alexander W; Fraser, James M; Webster, Paul J L

    2015-01-01

    Scanning optics enable many laser applications in manufacturing because their low inertia allows rapid movement of the process beam across the sample. We describe our method of inline coherent imaging for real-time (up to 230 kHz) micron-scale (7–8 µm axial resolution) tracking and control of laser machining depth through a scanning galvo-telecentric beam delivery system. For 1 cm trench etching in stainless steel, we collect high speed intrapulse and interpulse morphology which is useful for further understanding underlying mechanisms or comparison with numerical models. We also collect overall sweep-to-sweep depth penetration which can be used for feedback depth control. For trench etching in silicon, we show the relationship of etch rate with average power and scan speed by computer processing of depth information without destructive sample post-processing. We also achieve three-dimensional infrared continuous wave (modulated) laser machining of a 3.96 × 3.96 × 0.5 mm 3 (length × width × maximum depth) pattern on steel with depth feedback. To the best of our knowledge, this is the first successful demonstration of direct real-time depth monitoring and control of laser machining with scanning optics. (paper)

  19. A STUDY ABOUT TERRESTRIAL LASER SCANNING FOR RECONSTRUCTION OF PRECAST CONCRETE TO SUPPORT QLASSIC ASSESSMENT

    Directory of Open Access Journals (Sweden)

    M. A. Aziz

    2016-09-01

    Full Text Available Nowadays, terrestrial laser scanning shows the potential to improve construction productivity by measuring the objects changes using real-time applications. This paper presents the process of implementation of an efficient framework for precast concrete using terrestrial laser scanning that enables contractors to acquire accurate data and support Quality Assessment System in Construction (QLASSIC. Leica Scanstation C10, black/white target, Autodesk Revit and Cyclone software were used in this study. The results were compared with the dimensional of based model precast concrete given by the company as a reference with the AutoDesk Revit model from the terrestrial laser scanning data and conventional method (measuring tape. To support QLASSIC, the tolerance dimensions of cast in-situ & precast elements is +10mm / -5mm. The results showed that the root mean square error for a Revit model is 2.972mm while using measuring tape is 13.687mm. The accuracy showed that terrestrial laser scanning has an advantage in construction jobs to support QLASSIC.

  20. INITIAL TESTS AND ACCURACY ASSESMENT OF A COMPACT MOBILE LASER SCANNING SYSTEM

    Directory of Open Access Journals (Sweden)

    K. Julge

    2016-06-01

    Full Text Available Mobile laser scanning (MLS is a faster and cost-effective alternative to static laser scanning, even though there is a slight trade-off in accuracy. This contribution describes a compact mobile laser scanning system mounted on a vehicle. The technical parameters of the used system components, i.e. a small LIDAR sensor Velodyne VLP-16 and a dual antenna GNSS/INS system Advanced Navigation Spatial Dual, are reviewed, along with the integration of these components for spatial data acquisition. Calculation principles of 3D coordinates from the real-time data of all the involved sensors are discussed. The field tests were carried out in a controlled environment of a parking lot and at different velocities. Experiments were carried out to test the ability of the GNSS/INS system to cope with difficult conditions, e.g. sudden movements due to cornering or swerving. The accuracy of the resulting MLS point cloud is evaluated with respect to high-accuracy static terrestrial laser scanning data. Problems regarding combining LIDAR, GNSS and INS sensors are outlined, as well as the initial accuracy assessments. Initial tests revealed errors related to insufficient quality of inertial data and a need for the trajectory post-processing calculations. Although this study was carried out while the system was mounted on a car, there is potential for operating the system on an unmanned aerial vehicle, all-terrain vehicle or in a backpack mode due to its relatively compact size.

  1. Better Visualisation of Air-borne Laser Scanning for geomorphological and archaeological interpretation

    DEFF Research Database (Denmark)

    Ljungberg, Thomas; Scott, D; Kristiansen, Søren Munch

    Digital elevation models derived from high-precision Air-borne Laser Scanning (ALS or LiDAR) point clouds are becoming increasingly available throughout the world. These elevation models presents a very valuable tool for locating and interpreting geomorphological as well as archaeological features...

  2. Method for quantifying percentage wood failure in block-shear specimens by a laser scanning profilometer

    Science.gov (United States)

    C. T. Scott; R. Hernandez; C. Frihart; R. Gleisner; T. Tice

    2005-01-01

    A new method for quantifying percentage wood failure of an adhesively bonded block-shear specimen has been developed. This method incorporates a laser displacement gage with an automated two-axis positioning system that functions as a highly sensitive profilometer. The failed specimen is continuously scanned across its width to obtain a surface failure profile. The...

  3. Transient gels in colloid-polymer mixtures studied with fluorescence confocal scanning laser microscopy

    NARCIS (Netherlands)

    Verhaegh, N.A.M.; Asnaghi, D.; Lekkerkerker, H.N.W.

    1999-01-01

    We study the structure and the time evolution of transient gels formed in colloid-polymer mixtures, by means of uorescence Confocal Scanning Laser Microscopy (CSLM). This technique is used in conjunction with novel colloidal silica particles containing a uorescent core. The confocal micrographs

  4. Musculature of Notholca acuminata (Rotifera : Ploima : Brachionidae) revealed by confocal scanning laser microscopy

    DEFF Research Database (Denmark)

    Sørensen, M.V.; Funch, P.; Hooge, M.

    2003-01-01

    The body-wall and visceral musculature of Notholca acuminata was visualized using phalloidin-linked fluorescent dye under confocal laser scanning microscopy. The body-wall musculature includes dorsal, lateral, and ventral pairs of longitudinally oriented body retractor muscles, two pairs of head...

  5. An evaluation of the efficiency of laser scanning technology in the ...

    African Journals Online (AJOL)

    Green-Blue (RGB) intensity values for each point. Point clouds of data can now be imported into a CAD package and compared to design specifications. In the case where “as-built” specifications differ for the initial design, laser scanning allows ...

  6. Initial Tests and Accuracy Assesment of a Compact Mobile Laser Scanning System

    Science.gov (United States)

    Julge, K.; Ellmann, A.; Vajakas, T.; Kolka, R.

    2016-06-01

    Mobile laser scanning (MLS) is a faster and cost-effective alternative to static laser scanning, even though there is a slight trade-off in accuracy. This contribution describes a compact mobile laser scanning system mounted on a vehicle. The technical parameters of the used system components, i.e. a small LIDAR sensor Velodyne VLP-16 and a dual antenna GNSS/INS system Advanced Navigation Spatial Dual, are reviewed, along with the integration of these components for spatial data acquisition. Calculation principles of 3D coordinates from the real-time data of all the involved sensors are discussed. The field tests were carried out in a controlled environment of a parking lot and at different velocities. Experiments were carried out to test the ability of the GNSS/INS system to cope with difficult conditions, e.g. sudden movements due to cornering or swerving. The accuracy of the resulting MLS point cloud is evaluated with respect to high-accuracy static terrestrial laser scanning data. Problems regarding combining LIDAR, GNSS and INS sensors are outlined, as well as the initial accuracy assessments. Initial tests revealed errors related to insufficient quality of inertial data and a need for the trajectory post-processing calculations. Although this study was carried out while the system was mounted on a car, there is potential for operating the system on an unmanned aerial vehicle, all-terrain vehicle or in a backpack mode due to its relatively compact size.

  7. Laser Scanning Technology as Part of a Comprehensive Condition Assessment for Covered Bridges

    Science.gov (United States)

    Brian K. Brashaw; Samuel Anderson; Robert J. Ross

    2015-01-01

    New noncontact technologies have been developed and implemented for determining as-built condition and current dimensions for a wide variety of objects and buildings. In this study, a three-dimensional laser scanner was used to determine the dimensions and visual condition of a historic bridge in the Amnicon Falls State Park in northern Wisconsin. 3D scanning provides...

  8. Light propagation studies on laser modified waveguides using scanning near-field optical microscopy

    DEFF Research Database (Denmark)

    Borrise, X.; Berini, Abadal Gabriel; Jimenez, D.

    2001-01-01

    By means of direct laser writing on Al, a new method to locally modify optical waveguides is proposed. This technique has been applied to silicon nitride waveguides, allowing modifications of the optical propagation along the guide. To study the formed structures, a scanning near-held optical mic...

  9. a Study about Terrestrial Laser Scanning for Reconstruction of Precast Concrete to Support Qlassic Assessment

    Science.gov (United States)

    Aziz, M. A.; Idris, K. M.; Majid, Z.; Ariff, M. F. M.; Yusoff, A. R.; Luh, L. C.; Abbas, M. A.; Chong, A. K.

    2016-09-01

    Nowadays, terrestrial laser scanning shows the potential to improve construction productivity by measuring the objects changes using real-time applications. This paper presents the process of implementation of an efficient framework for precast concrete using terrestrial laser scanning that enables contractors to acquire accurate data and support Quality Assessment System in Construction (QLASSIC). Leica Scanstation C10, black/white target, Autodesk Revit and Cyclone software were used in this study. The results were compared with the dimensional of based model precast concrete given by the company as a reference with the AutoDesk Revit model from the terrestrial laser scanning data and conventional method (measuring tape). To support QLASSIC, the tolerance dimensions of cast in-situ & precast elements is +10mm / -5mm. The results showed that the root mean square error for a Revit model is 2.972mm while using measuring tape is 13.687mm. The accuracy showed that terrestrial laser scanning has an advantage in construction jobs to support QLASSIC.

  10. Multimodal scanning laser ophthalmoscopy for image guided treatment of age-related macular degeneration

    Science.gov (United States)

    Hammer, Daniel X.; Ferguson, R. D.; Patel, Ankit H.; Iftimia, Nicusor V.; Mujat, Mircea; Husain, Deeba

    2009-02-01

    Subretinal neovascular membranes (SRNM) are a deleterious complication of laser eye injury and retinal diseases such as age-related macular degeneration (AMD), choroiditis, and myopic retinopathy. Photodynamic therapy (PDT) and anti-vascular endothelial growth factor (VEGF) drugs are approved treatment methods. PDT acts by selective dye accumulation, activation by laser light, and disruption and clotting of the new leaky vessels. However, PDT surgery is currently not image-guided, nor does it proceed in an efficient or automated manner. This may contribute to the high rate of re-treatment. We have developed a multimodal scanning laser ophthalmoscope (SLO) for automated diagnosis and image-guided treatment of SRNMs associated with AMD. The system combines line scanning laser ophthalmoscopy (LSLO), fluorescein angiography (FA), indocyanine green angiography (ICGA), PDT laser delivery, and retinal tracking in a compact, efficient platform. This paper describes the system hardware and software design, performance characterization, and automated patient imaging and treatment session procedures and algorithms. Also, we present initial imaging and tracking measurements on normal subjects and automated lesion demarcation and sizing analysis of previously acquired angiograms. Future pre-clinical testing includes line scanning angiography and PDT treatment of AMD subjects. The automated acquisition procedure, enhanced and expedited data post-processing, and innovative image visualization and interpretation tools provided by the multimodal retinal imager may eventually aid in the diagnosis, treatment, and prognosis of AMD and other retinal diseases.

  11. ANALYSIS OF TERRESTRIAL LASER SCANNING AND PHOTOGRAMMETRY DATA FOR DOCUMENTATION OF HISTORICAL ARTIFACTS

    Directory of Open Access Journals (Sweden)

    R. A. Kuçak

    2016-10-01

    Full Text Available Historical artifacts living from the past until today exposed to many destructions non-naturally or naturally. For this reason, The protection and documentation studies of Cultural Heritage to inform the next generations are accelerating day by day in the whole world. The preservation of historical artifacts using advanced 3D measurement technologies becomes an efficient tool for mapping solutions. There are many methods for documentation and restoration of historic structures. In addition to traditional methods such as simple hand measurement and tachometry, terrestrial laser scanning is rapidly becoming one of the most commonly used techniques due to its completeness, accuracy and fastness characteristics. This study evaluates terrestrial laser scanning(TLS technology and photogrammetry for documenting the historical artifacts facade data in 3D Environment. PhotoModeler software developed by Eos System was preferred for Photogrammetric method. Leica HDS 6000 laser scanner developed by Leica Geosystems and Cyclone software which is the laser data evaluation software belonging to the company is preferred for Terrestrial Laser Scanning method. Taking into account the results obtained with this software product is intended to provide a contribution to the studies for the documentation of cultural heritage.

  12. Automatic Stem Mapping by Merging Several Terrestrial Laser Scans at the Feature and Decision Levels

    Directory of Open Access Journals (Sweden)

    Juha Hyyppä

    2013-01-01

    Full Text Available Detailed up-to-date ground reference data have become increasingly important in quantitative forest inventories. Field reference data are conventionally collected at the sample plot level by means of manual measurements, which are both labor-intensive and time-consuming. In addition, the number of attributes collected from the tree stem is limited. More recently, terrestrial laser scanning (TLS, using both single-scan and multi-scan techniques, has proven to be a promising solution for efficient stem mapping at the plot level. In the single-scan method, the laser scanner is placed at the center of the plot, creating only one scan, and all trees are mapped from the single-scan point cloud. Consequently, the occlusion of stems increases as the range of the scanner increases, depending on the forest’s attributes. In the conventional multi-scan method, several scans are made simultaneously inside and outside of the plot to collect point clouds representing all trees within the plot, and these scans are accurately co-registered by using artificial reference targets manually placed throughout the plot. The additional difficulty of applying the multi-scan method is due to the point-cloud registration of several scans not being fully automated yet. This paper proposes a multi-single-scan (MSS method to map the sample plot. The method does not require artificial reference targets placed on the plot or point-level registration. The MSS method is based on the fully automated processing of each scan independently and on the merging of the stem positions automatically detected from multiple scans to accurately map the sample plot. The proposed MSS method was tested on five dense forest plots. The results show that the MSS method significantly improves the stem-detection accuracy compared with the single-scan approach and achieves a mapping accuracy similar to that achieved with the multi-scan method, without the need for the point-level registration.

  13. Tritium Removal from Codeposits on Carbon Tiles by a Scanning Laser

    International Nuclear Information System (INIS)

    C.H. Skinner; C.A. Gentile; A. Carpe; G. Guttadora; S. Langish; K.M. Young; W.M. Shu; H. Nakamura

    2001-01-01

    A novel method for tritium release has been demonstrated on codeposited layers on graphite and carbon-fiber-composite tiles from the Tokamak Fusion Test Reactor (TFTR). A scanning continuous wave Nd laser beam heated the codeposits to a temperature of 1200-2300 degrees C for 10 to 200 milliseconds in an argon atmosphere. The temperature rise of the codeposit was significantly higher than that of the manufactured tile material (e.g., 1770 degrees C cf. 1080 degrees C). A major fraction of tritium was thermally desorbed with minimal change to the surface appearance at a laser intensity of 8 kW/cm(superscript ''2''), peak temperatures above 1230 degrees C and heating duration 10-20 milliseconds. In two experiments, 46% and 84% of the total tritium was released during the laser scan. The application of this method for tritium removal from a tokamak reactor appears promising and has significant advantages over oxidative techniques

  14. Forest Resource Measurements by Combination of Terrestrial Laser Scanning and Drone Use

    Science.gov (United States)

    Cheung, K.; Katoh, M.; Horisawa, M.

    2017-10-01

    Using terrestrial laser scanning (TLS), forest attributes such as diameter at breast height (DBH) and tree location can be measured accurately. However, due to low penetration of laser pulses to tree tops, tree height measurements are typically underestimated. In this study, data acquired by TLS and drones were combined; DBH and tree locations were determined by TLS, and tree heights were measured by drone use. The average tree height error and root mean square error (RMSE) of tree height were 0.8 and 1.2 m, respectively, for the combined method, and -0.4 and 1.7 m using TLS alone. The tree height difference was compared using airborne laser scanning (ALS). Furthermore, a method to acquire 100 % tree detection rate based on TLS data is suggested in this study.

  15. A novel near real-time laser scanning device for geometrical determination of pleural cavity surface.

    Science.gov (United States)

    Kim, Michele M; Zhu, Timothy C

    2013-02-02

    During HPPH-mediated pleural photodynamic therapy (PDT), it is critical to determine the anatomic geometry of the pleural surface quickly as there may be movement during treatment resulting in changes with the cavity. We have developed a laser scanning device for this purpose, which has the potential to obtain the surface geometry in real-time. A red diode laser with a holographic template to create a pattern and a camera with auto-focusing abilities are used to scan the cavity. In conjunction with a calibration with a known surface, we can use methods of triangulation to reconstruct the surface. Using a chest phantom, we are able to obtain a 360 degree scan of the interior in under 1 minute. The chest phantom scan was compared to an existing CT scan to determine its accuracy. The laser-camera separation can be determined through the calibration with 2mm accuracy. The device is best suited for environments that are on the scale of a chest cavity (between 10cm and 40cm). This technique has the potential to produce cavity geometry in real-time during treatment. This would enable PDT treatment dosage to be determined with greater accuracy. Works are ongoing to build a miniaturized device that moves the light source and camera via a fiber-optics bundle commonly used for endoscopy with increased accuracy.

  16. Error analysis of motion correction method for laser scanning of moving objects

    Science.gov (United States)

    Goel, S.; Lohani, B.

    2014-05-01

    The limitation of conventional laser scanning methods is that the objects being scanned should be static. The need of scanning moving objects has resulted in the development of new methods capable of generating correct 3D geometry of moving objects. Limited literature is available showing development of very few methods capable of catering to the problem of object motion during scanning. All the existing methods utilize their own models or sensors. Any studies on error modelling or analysis of any of the motion correction methods are found to be lacking in literature. In this paper, we develop the error budget and present the analysis of one such `motion correction' method. This method assumes availability of position and orientation information of the moving object which in general can be obtained by installing a POS system on board or by use of some tracking devices. It then uses this information along with laser scanner data to apply correction to laser data, thus resulting in correct geometry despite the object being mobile during scanning. The major application of this method lie in the shipping industry to scan ships either moving or parked in the sea and to scan other objects like hot air balloons or aerostats. It is to be noted that the other methods of "motion correction" explained in literature can not be applied to scan the objects mentioned here making the chosen method quite unique. This paper presents some interesting insights in to the functioning of "motion correction" method as well as a detailed account of the behavior and variation of the error due to different sensor components alone and in combination with each other. The analysis can be used to obtain insights in to optimal utilization of available components for achieving the best results.

  17. A confocal scanning laser ophthalmoscope for retinal vessel oximetry

    Science.gov (United States)

    Lompado, Arthur

    Measurement of a person's blood oxygen saturation has long been recognized as a useful metric for the characterizing ailments ranging from chronic respiratory disorders to acute, potentially life threatening, traumas. The ubiquity of oxygen saturation monitors in the medical field, including portable pulse oximeters and laboratory based CO-oximeters, is a testament to the importance of this technique. The work presented here documents the design, fabrication and development of a unique type of oxygen saturation monitor, a confocal scanning retinal vessel oximeter, with the potential to expand the usefulness of the present devices. A large part of the knowledge base required to construct the instrument comes from the consideration of light scattering by red blood cells in a blood vessel. Therefore, a substantial portion of this work is devoted to the process of light scattering by whole human blood and its effects on the development of a more accurate oximeter. This light scattering effect has been both measured and modeled stochastically to determine its contribution to the measured oximeter signal. It is shown that, although well accepted in the published literature, the model only correlates marginally to the measurements due to inherent limitations imposed by the model assumptions. Nonetheless, enough material has been learned about the scattering to allow development of a mathematical model for the interaction of light with blood in a vessel, and this knowledge has been applied to the data reduction of the present oximeter. This data reduction technique has been tested in a controlled experiment employing a model eye with a blood filled mock retinal vessel. It will be shown that the presently developed technique exhibited strong correlation between the known blood oxygen saturation and that calculated by the new system.

  18. Self-mixing laser diode included in scanning microwave microscope to the control of probe nanodisplacement

    Science.gov (United States)

    Usanov, D. A.; Skripal, A. V.; Astakhov, E. I.; Dobdin, S. Y.

    2018-04-01

    The possibilities of self-mixing interferometry for measuring nanodisplacement of a probe included in a near-field scanning microwave microscope have been considered. The features of the formation of a laser interference signal at current modulation of the wavelength of laser radiation have been investigated. Experimental responses of a semiconductor laser system included in scanning microwave microscope to control nanodisplacement of the probe have been demonstrated.To register the nanodisplacement of the probe, it is proposed to use the method of determining the stationary phase of a laser interference signal by low-frequency spectrum of a semiconductor laser. The change of the amplitudes of the spectral components in the spectrum of the interference signal due to creation of the standing wave in the external resonator of the laser self-mixing system has been shown. The form of the interference signal at current modulation of the radiation wavelength was experimentally obtained when the probe moves with a step of 80 nm. The results of measuring nanodisplacements of an electromagnetic translator STANDA 8MVT40-13 have been demonstrated. Deviation of the nanodisplacement of the proposed method does not exceed 15%.

  19. Automated inspection of gaps on the free-form shape parts by laser scanning technologies

    Science.gov (United States)

    Zhou, Sen; Xu, Jian; Tao, Lei; An, Lu; Yu, Yan

    2018-01-01

    In industrial manufacturing processes, the dimensional inspection of the gaps on the free-form shape parts is critical and challenging, and is directly associated with subsequent assembly and terminal product quality. In this paper, a fast measuring method for automated gap inspection based on laser scanning technologies is presented. The proposed measuring method consists of three steps: firstly, the relative position is determined according to the geometric feature of measuring gap, which considers constraints existing in a laser scanning operation. Secondly, in order to acquire a complete gap profile, a fast and effective scanning path is designed. Finally, the range dimension of the gaps on the free-form shape parts including width, depth and flush, correspondingly, is described in a virtual environment. In the future, an appliance machine based on the proposed method will be developed for the on-line dimensional inspection of gaps on the automobile or aerospace production line.

  20. Capturing and modelling high-complex alluvial topography with UAS-borne laser scanning

    Science.gov (United States)

    Mandlburger, Gottfried; Wieser, Martin; Pfennigbauer, Martin

    2015-04-01

    Due to fluvial activity alluvial forests are zones of highest complexity and relief energy. Alluvial forests are dominated by new and pristine channels in consequence of current and historic flood events. Apart from topographic features, the vegetation structure is typically very complex featuring, both, dense under story as well as high trees. Furthermore, deadwood and debris carried from upstream during periods of high discharge within the river channel are deposited in these areas. Therefore, precise modelling of the micro relief of alluvial forests using standard tools like Airborne Laser Scanning (ALS) is hardly feasible. Terrestrial Laser Scanning (TLS), in turn, is very time consuming for capturing larger areas as many scan positions are necessary for obtaining complete coverage due to view occlusions in the forest. In the recent past, the technological development of Unmanned Arial Systems (UAS) has reached a level that light-weight survey-grade laser scanners can be operated from these platforms. For capturing alluvial topography this could bridge the gap between ALS and TLS in terms of providing a very detailed description of the topography and the vegetation structure due to the achievable very high point density of >100 points per m2. In our contribution we demonstrate the feasibility to apply UAS-borne laser scanning for capturing and modelling the complex topography of the study area Neubacher Au, an alluvial forest at the pre-alpine River Pielach (Lower Austria). The area was captured with Riegl's VUX-1 compact time-of-flight laser scanner mounted on a RiCopter (X-8 array octocopter). The scanner features an effective scan rate of 500 kHz and was flown in 50-100 m above ground. At this flying height the laser footprint is 25-50 mm allowing mapping of very small surface details. Furthermore, online waveform processing of the backscattered laser energy enables the retrieval of multiple targets for single laser shots resulting in a dense point cloud of

  1. Keypoint-based 4-Points Congruent Sets - Automated marker-less registration of laser scans

    Science.gov (United States)

    Theiler, Pascal Willy; Wegner, Jan Dirk; Schindler, Konrad

    2014-10-01

    We propose a method to automatically register two point clouds acquired with a terrestrial laser scanner without placing any markers in the scene. What makes this task challenging are the strongly varying point densities caused by the line-of-sight measurement principle, and the huge amount of data. The first property leads to low point densities in potential overlap areas with scans taken from different viewpoints while the latter calls for highly efficient methods in terms of runtime and memory requirements. A crucial yet largely unsolved step is the initial coarse alignment of two scans without any simplifying assumptions, that is, point clouds are given in arbitrary local coordinates and no knowledge about their relative orientation is available. Once coarse alignment has been solved, scans can easily be fine-registered with standard methods like least-squares surface or Iterative Closest Point matching. In order to drastically thin out the original point clouds while retaining characteristic features, we resort to extracting 3D keypoints. Such clouds of keypoints, which can be viewed as a sparse but nevertheless discriminative representation of the original scans, are then used as input to a very efficient matching method originally developed in computer graphics, called 4-Points Congruent Sets (4PCS) algorithm. We adapt the 4PCS matching approach to better suit the characteristics of laser scans. The resulting Keypoint-based 4-Points Congruent Sets (K-4PCS) method is extensively evaluated on challenging indoor and outdoor scans. Beyond the evaluation on real terrestrial laser scans, we also perform experiments with simulated indoor scenes, paying particular attention to the sensitivity of the approach with respect to highly symmetric scenes.

  2. Function analysis of working integrated circuit with scanning laser microscope. Laser kenbikyo ni yoru IC no dosa kansatsu

    Energy Technology Data Exchange (ETDEWEB)

    Ode, T. (Lasertec Corp., Kanagawa (Japan))

    1992-10-20

    By scanning a laser light, the reaction of a specimen against the light is detected in some means. The optical effect can be visualized by displaying that on the CRT or the like in synchronism with the scanning. Among these, an image formed and visualized by internal photoelectric effect by light is called OBIC image, and chiefly used for evaluating and analyzing semiconductor devices. Observing this OBIC image by a high speed scanning laser microscope has been spotlighted these days as an effective means for observing the state of p-n junction of an IC in operation. This paper descries the principle, the observing method, the detecting circuit, etc. of the semiconductor observing method using a laser microscope. Further, actual examples of detecting defects of an IC by means of OBIC image are shown. As for the problem, since leak parts are displayed as negative contrast in the OBIC image to affect finding work of leak part, the necessity of improvement is pointed out. 39 refs., 11 figs.

  3. Comparison of 3d Reconstruction Services and Terrestrial Laser Scanning for Cultural Heritage Documentation

    Science.gov (United States)

    Rasztovits, S.; Dorninger, P.

    2013-07-01

    Terrestrial Laser Scanning (TLS) is an established method to reconstruct the geometrical surface of given objects. Current systems allow for fast and efficient determination of 3D models with high accuracy and richness in detail. Alternatively, 3D reconstruction services are using images to reconstruct the surface of an object. While the instrumental expenses for laser scanning systems are high, upcoming free software services as well as open source software packages enable the generation of 3D models using digital consumer cameras. In addition, processing TLS data still requires an experienced user while recent web-services operate completely automatically. An indisputable advantage of image based 3D modeling is its implicit capability for model texturing. However, the achievable accuracy and resolution of the 3D models is lower than those of laser scanning data. Within this contribution, we investigate the results of automated web-services for image based 3D model generation with respect to a TLS reference model. For this, a copper sculpture was acquired using a laser scanner and using image series of different digital cameras. Two different webservices, namely Arc3D and AutoDesk 123D Catch were used to process the image data. The geometric accuracy was compared for the entire model and for some highly structured details. The results are presented and interpreted based on difference models. Finally, an economical comparison of the generation of the models is given considering the interactive and processing time costs.

  4. 3D laser scanning and modelling of the Dhow heritage for the Qatar National Museum

    Science.gov (United States)

    Wetherelt, A.; Cooper, J. P.; Zazzaro, C.

    2014-08-01

    Curating boats can be difficult. They are complex structures, often demanding to conserve whether in or out of the water; they are usually large, difficult to move on land, and demanding of gallery space. Communicating life on board to a visiting public in the terra firma context of a museum can be difficult. Boats in their native environment are inherently dynamic artifacts. In a museum they can be static and divorced from the maritime context that might inspire engagement. New technologies offer new approaches to these problems. 3D laser scanning and digital modeling offers museums a multifaceted means of recording, monitoring, studying and communicating watercraft in their care. In this paper we describe the application of 3D laser scanning and subsequent digital modeling. Laser scans were further developed using computer-generated imagery (CGI) modeling techniques to produce photorealistic 3D digital models for development into interactive, media-based museum displays. The scans were also used to generate 2D naval lines and orthographic drawings as a lasting curatorial record of the dhows held by the National Museum of Qatar.

  5. Inspection of float glass using a novel retroreflective laser scanning system

    Science.gov (United States)

    Holmes, Jonathan D.

    1997-07-01

    Since 1988, Image Automation has marketed a float glass inspection system using a novel retro-reflective laser scanning system. The (patented) instrument scans a laser beam by use of a polygon through the glass onto a retro-reflective screen, and collects the retro-reflected light off the polygon, such that a stationary image of the moving spot on the screen is produced. The spot image is then analyzed for optical effects introduced by defects within the glass, which typically distort and attenuate the scanned laser beam, by use of suitable detectors. The inspection system processing provides output of defect size, shape and severity, to the factory network for use in rejection or sorting of glass plates to the end customer. This paper briefly describes the principles of operation, the system architecture, and limitations to sensitivity and measurement repeatability. New instruments based on the retro-reflective scanning method have recently been developed. The principles and implementation are described. They include: (1) Simultaneous detection of defects within the glass and defects in a mirror coating on the glass surface using polarized light. (2) A novel distortion detector for very dark glass. (3) Measurement of optical quality (flatness/refractive homogeneity) of the glass using a position sensitive detector.

  6. Wafer-level vacuum packaged resonant micro-scanning mirrors for compact laser projection displays

    Science.gov (United States)

    Hofmann, Ulrich; Oldsen, Marten; Quenzer, Hans-Joachim; Janes, Joachim; Heller, Martin; Weiss, Manfred; Fakas, Georgios; Ratzmann, Lars; Marchetti, Eleonora; D'Ascoli, Francesco; Melani, Massimiliano; Bacciarelli, Luca; Volpi, Emilio; Battini, Francesco; Mostardini, Luca; Sechi, Francesco; De Marinis, Marco; Wagner, Bernd

    2008-02-01

    Scanning laser projection using resonant actuated MEMS scanning mirrors is expected to overcome the current limitation of small display size of mobile devices like cell phones, digital cameras and PDAs. Recent progress in the development of compact modulated RGB laser sources enables to set up very small laser projection systems that become attractive not only for consumer products but also for automotive applications like head-up and dash-board displays. Within the last years continuous progress was made in increasing MEMS scanner performance. However, only little is reported on how mass-produceability of these devices and stable functionality even under harsh environmental conditions can be guaranteed. Automotive application requires stable MEMS scanner operation over a wide temperature range from -40° to +85°Celsius. Therefore, hermetic packaging of electrostatically actuated MEMS scanning mirrors becomes essential to protect the sensitive device against particle contamination and condensing moisture. This paper reports on design, fabrication and test of a resonant actuated two-dimensional micro scanning mirror that is hermetically sealed on wafer level. With resonant frequencies of 30kHz and 1kHz, an achievable Theta-D-product of 13mm.deg and low dynamic deformation <20nm RMS it targets Lissajous projection with SVGA-resolution. Inevitable reflexes at the vacuum package surface can be seperated from the projection field by permanent inclination of the micromirror.

  7. Nano-pulsed laser irradiation scanning system for phase-change materials

    International Nuclear Information System (INIS)

    Kim, Sookyung; Li Xuezhe; Lee, Sangbin; Kim, Kyung-Ho; Lee, Seung-Yop

    2008-01-01

    Recently, the demand of a laser irradiation tester is increasing for phase change random access memory (PRAM) as well as conventional optical storage media. In this study, a nano-pulsed laser irradiation system is developed to characterize the optical property and writing performance of phase-change materials, based on a commercially available digital versatile disk (DVD) optical pick-up. The precisely controlled focusing and scanning on the material's surface are implemented using the auto-focusing mechanism and a voice coil motor (VCM) of the commercial DVD pick-up. The laser irradiation system provides various writing and reading functions such as adjustable laser power, pulse duration, recording pattern (spot, line and area), and writing/reading repetition, phase transition, and in situ reflectivity measurement before/after irradiation. Measurements of power time effect (PTE) diagram and reflectivity map of Ge 2 Sb 2 Te 5 samples show that the proposed laser irradiation system provides the powerful scanning tool to quantify the optical characteristics of phase-change materials

  8. Laser scanning endoscope via an imaging fiber bundle for fluorescence imaging

    Science.gov (United States)

    Yeboah, Lorenz D.; Nestler, Dirk; Steiner, Rudolf W.

    1994-12-01

    Based on a laser scanning endoscope via an imaging fiber bundle, a new approach for a tumor diagnostic system has been developed to assist physicians in the diagnosis before the actual PDT is carried out. Laser induced, spatially resolved fluorescence images of diseased tissue can be compared with images received by video endoscopy using a white light source. The set- up is required to produce a better contrast between infected and healthy tissue and might serve as a constructive diagnostic help for surgeons. The fundamental idea is to scan a low-power laser beam on an imaging fiber bundle and to achieve a spatially resolved projection on the tissue surface. A sufficiently high laser intensity from the diode laser is concentrated on each single spot of the tissue exciting fluorescence when a dye has previously been accumulated. Subsequently, video image of the tissue is recorded and stored. With an image processing unit, video and fluorescence images are overlaid producing a picture of the fluorescence intensity in the environment of the observed tissue.

  9. New opportunities for astronomical polarimetry

    International Nuclear Information System (INIS)

    Hough, J.H.

    2007-01-01

    Polarimetry has played an important role in many areas of astronomy, through the direct production of polarized flux in synchrotron and cyclotron radiation and the polarized emission from a medium of aligned dust grains (dichroic emission), and its production in secondary processes such as scattering and selective absorption in a medium of aligned grains (dichroic absorption). Future polarimetry at optical and infrared wavelengths, with the new generation of large telescopes and the use of adaptive optics, will provide important advances from the nearby universe to very high redshifts

  10. Correlative Analysis of Immunoreactivity in Confocal Laser-Scanning Microscopy and Scanning Electron Microscopy with Focused Ion Beam Milling

    Directory of Open Access Journals (Sweden)

    Takahiro eSonomura

    2013-02-01

    Full Text Available Three-dimensional reconstruction of ultrastructure of rat brain with minimal effort has recently been realized by scanning electron microscopy combined with focused ion beam milling (FIB-SEM. Because application of immunohistochemical staining to electron microscopy has a great advantage in that molecules of interest are specifically localized in ultrastructures, we here tried to apply immunocytochemistry to FIB-SEM and correlate immunoreactivity in confocal laser-scanning microcopy (CF-LSM with that in FIB-SEM. The dendrites of medium-sized spiny neurons in rat neostriatum were visualized with a recombinant viral vector, which labeled the infected neurons with membrane-targeted GFP in a Golgi stain-like fashion, and thalamostriatal afferent terminals were immunolabeled with Cy5 fluorescence for vesicular glutamate transporter 2 (VGluT2. After detecting the sites of terminals apposed to the dendrites in CF-LSM, GFP and VGluT2 immunoreactivities were further developed for electron microscopy by the immunogold/silver enhancement and immunoperoxidase/diaminobenzidine (DAB methods, respectively. In the contrast-inverted FIB-SEM images, silver precipitation and DAB deposits were observed as fine dark grains and diffuse dense profiles, respectively, indicating that these immunoreactivities were easily recognizable as in the images of transmission electron microscopy. In the sites of interest, some appositions were revealed to display synaptic specialization of asymmetric type. The present method is thus useful in the three-dimensional analysis of immunocytochemically differentiated synaptic connection in the central neural circuit.

  11. Generation of 3D Virtual Geographic Environment Based on Laser Scanning Technique

    Institute of Scientific and Technical Information of China (English)

    DU Jie; CHEN Xiaoyong; FumioYamazaki

    2003-01-01

    This paper demonstrates an experiment on the generation of 3D virtual geographic environment on the basis of experimental flight laser scanning data by a set of algorithms and methods that were developed to automatically interpret range images for extracting geo-spatial features and then to reconstruct geo-objects. The algorithms and methods for the interpretation and modeling of laser scanner data include triangulated-irregular-network (TIN)-based range image interpolation ; mathematical-morphology(MM)-based range image filtering,feature extraction and range image segmentation, feature generalization and optimization, 3D objects reconstruction and modeling; computergraphics (CG)-based visualization and animation of geographic virtual reality environment.

  12. Brief communication "Application of mobile laser scanning in snow cover profiling"

    Directory of Open Access Journals (Sweden)

    S. Kaasalainen

    2011-03-01

    Full Text Available We present a snowmobile-based mobile mapping system and its first application to snow cover roughness and change detection measurement. The ROAMER mobile mapping system, constructed at the Finnish Geodetic Institute, consists of the positioning and navigating systems, a terrestrial laser scanner, and the carrying platform (a snowmobile sledge in this application. We demonstrate the applicability of the instrument to snow cover roughness profiling and change detection by presenting preliminary results from a mobile laser scanning (MLS campaign. The results show the potential of MLS for fast and efficient snow profiling from large areas in a millimetre scale.

  13. The Investigation of Accuracy of 3 Dimensional Models Generated From Point Clouds with Terrestrial Laser Scanning

    Science.gov (United States)

    Gumus, Kutalmis; Erkaya, Halil

    2013-04-01

    In Terrestrial laser scanning (TLS) applications, it is necessary to take into consideration the conditions that affect the scanning process, especially the general characteristics of the laser scanner, geometric properties of the scanned object (shape, size, etc.), and its spatial location in the environment. Three dimensional models obtained with TLS, allow determining the geometric features and relevant magnitudes of the scanned object in an indirect way. In order to compare the spatial location and geometric accuracy of the 3-dimensional model created by Terrestrial laser scanning, it is necessary to use measurement tools that give more precise results than TLS. Geometric comparisons are performed by analyzing the differences between the distances, the angles between surfaces and the measured values taken from cross-sections between the data from the 3-dimensional model created with TLS and the values measured by other measurement devices The performance of the scanners, the size and shape of the scanned objects are tested using reference objects the sizes of which are determined with high precision. In this study, the important points to consider when choosing reference objects were highlighted. The steps up to processing the point clouds collected by scanning, regularizing these points and modeling in 3 dimensions was presented visually. In order to test the geometric correctness of the models obtained by Terrestrial laser scanners, sample objects with simple geometric shapes such as cubes, rectangular prisms and cylinders that are made of concrete were used as reference models. Three dimensional models were generated by scanning these reference models with Trimble Mensi GS 100. The dimension of the 3D model that is created from point clouds was compared with the precisely measured dimensions of the reference objects. For this purpose, horizontal and vertical cross-sections were taken from the reference objects and generated 3D models and the proximity of

  14. Multi-objective optimization of cellular scanning strategy in selective laser melting

    DEFF Research Database (Denmark)

    Ahrari, Ali; Deb, Kalyanmoy; Mohanty, Sankhya

    2017-01-01

    The scanning strategy for selective laser melting - an additive manufacturing process - determines the temperature fields during the manufacturing process, which in turn affects residual stresses and distortions, two of the main sources of process-induced defects. The goal of this study is to dev......The scanning strategy for selective laser melting - an additive manufacturing process - determines the temperature fields during the manufacturing process, which in turn affects residual stresses and distortions, two of the main sources of process-induced defects. The goal of this study......, the problem is a combination of combinatorial and choice optimization, which makes the problem difficult to solve. On a process simulation domain consisting of 32 cells, our multi-objective evolutionary method is able to find a set of trade-off solutions for the defined conflicting objectives, which cannot...

  15. Development of Large Concrete Object Geometrical Model Based on Terrestrial Laser Scanning

    Directory of Open Access Journals (Sweden)

    Zaczek-Peplinska Janina

    2015-02-01

    Full Text Available The paper presents control periodic measurements of movements and survey of concrete dam on Dunajec River in Rożnów, Poland. Topographical survey was conducted using laser scanning technique. The goal of survey was data collection and creation of a geometrical model. Acquired cross- and horizontal sections were utilised to create a numerical model of object behaviour at various load depending of changing level of water in reservoir. Modelling was accomplished using finite elements technique. During the project an assessment was conducted to terrestrial laser scanning techniques for such type of research of large hydrotechnical objects such as gravitational water dams. Developed model can be used to define deformations and displacement prognosis.

  16. Microstructures and Microhardness Properties of CMSX-4® Additively Fabricated Through Scanning Laser Epitaxy (SLE)

    Science.gov (United States)

    Basak, Amrita; Holenarasipura Raghu, Shashank; Das, Suman

    2017-12-01

    Epitaxial CMSX-4® deposition is achieved on CMSX-4® substrates through the scanning laser epitaxy (SLE) process. A thorough analysis is performed using various advanced material characterization techniques, namely high-resolution optical microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction, and Vickers microhardness measurements, to characterize and compare the quality of the SLE-fabricated CMSX-4® deposits to the CMSX-4® substrates. The results show that the CMSX-4® deposits have smaller primary dendritic arm spacing, finer γ/ γ' size, weaker elemental segregation, and higher microhardness compared to the investment cast CMSX-4® substrates. The results presented here demonstrate that CMSX-4® is an attractive material for laser-based AM processing and, therefore, can be used in the fabrication of gas turbine hot-section components through AM processing.

  17. As- built inventory of the office building with the use of terrestrial laser scanning

    Science.gov (United States)

    Przyborski, Marek; Tysiąc, Paweł

    2018-01-01

    Terrestrial Laser Scanning (TLS) is an efficient tool for building inventories. Based on the red- laser beam technology it is possible to provide the high accuracy data with complete spatial information about a scanned object. In this article, authors present the solution of use a TLS in as-built inventory of the office building. Based on the provided data, it is possible to evaluate the correctness of built details of a building and provide information for further construction works, for example an area needed for Styrofoam installation. The biggest problem in this research is that an error which equals over 1cm could generate costs, which could be a problem to cover by a constructor. Based on a complicated place of the construction works (centre of a city) it was a challenge to maintain the accuracy.

  18. As- built inventory of the office building with the use of terrestrial laser scanning

    Directory of Open Access Journals (Sweden)

    Przyborski Marek

    2018-01-01

    Full Text Available Terrestrial Laser Scanning (TLS is an efficient tool for building inventories. Based on the red- laser beam technology it is possible to provide the high accuracy data with complete spatial information about a scanned object. In this article, authors present the solution of use a TLS in as-built inventory of the office building. Based on the provided data, it is possible to evaluate the correctness of built details of a building and provide information for further construction works, for example an area needed for Styrofoam installation. The biggest problem in this research is that an error which equals over 1cm could generate costs, which could be a problem to cover by a constructor. Based on a complicated place of the construction works (centre of a city it was a challenge to maintain the accuracy.

  19. Damage Detection on Thin-walled Structures Utilizing Laser Scanning and Standing Waves

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Se Hyeok; Jeon, Jun Young; Kim, Du Hwan; Park, Gyuhae [Chonnam Nat’l Univ., Gwangju (Korea, Republic of); Kang, To; Han, Soon Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-05-15

    This paper describes wavenumber filtering for damage detection using single-frequency standing wave excitation and laser scanning sensing. An embedded piezoelectric sensor generates ultrasonic standing waves, and the responses are measured using a laser Doppler vibrometer and mirror tilting device. After scanning, newly developed damage detection techniques based on wavenumber filtering are applied to the full standing wave field. To demonstrate the performance of the proposed techniques, several experiments were performed on composite plates with delamination and aluminum plates with corrosion damage. The results demonstrated that the developed techniques could be applied to various structures to localize the damage, with the potential to improve the damage detection capability at a high interrogation speed.

  20. Application of the laser scanning confocal microscope in fluorescent film sensor research

    Science.gov (United States)

    Zhang, Hongyan; Liu, Wei-Min; Zhao, Wen-Wen; Dai, Qing; Wang, Peng-Fei

    2010-10-01

    Confocal microscopy offers several advantages over conventional optical microscopy; we show an experimental investigation laser scanning confocal microscope as a tool to be used in cubic boron nitride (cBN) film-based fluorescent sensor research. Cubic boron nitride cBN film sensors are modified with dansyl chloride and rhodamine B isothiocyanate respectively. Fluorescent modification quality on the cubic boron nitride film is clearly express and the sensor ability to Hg2+ cations and pH are investigated in detail. We evidence the rhodamine B isothiocyanate modified quality on cBN surface is much better than that of dansyl chloride. And laser scanning confocal microscope has potential application lighttight fundus film fluorescent sensor research.

  1. In vivo visualization of microneedle conduits in human skin using laser scanning microscopy

    International Nuclear Information System (INIS)

    Bal, S; Kruithof, A C; Bouwstra, J; Liebl, H; Tomerius, M; Lademann, J; Meinke, M

    2010-01-01

    Solid microneedles enhance the penetration of drugs into the viable skin but little is known about the geometry of the conduits in vivo. Therefore, laser scanning microscopy was used to visualize the conduits of a microneedle system with needles at a length of 300 μm in 6 healthy subjects over a period of time. The model drug, a fluorescent dye was applied before and after piercing. Laser scanning microscopy was evaluated as being an excellent method to monitor the geometry and closure of the conduits over time. The used microneedle system was evaluated as suitable to enhance the transport of model drugs into the viable epidermis without bleeding and a short closure time of the conduits at the skin surface

  2. In vivo visualization of microneedle conduits in human skin using laser scanning microscopy

    Science.gov (United States)

    Bal, S.; Kruithof, A. C.; Liebl, H.; Tomerius, M.; Bouwstra, J.; Lademann, J.; Meinke, M.

    2010-03-01

    Solid microneedles enhance the penetration of drugs into the viable skin but little is known about the geometry of the conduits in vivo. Therefore, laser scanning microscopy was used to visualize the conduits of a microneedle system with needles at a length of 300 μm in 6 healthy subjects over a period of time. The model drug, a fluorescent dye was applied before and after piercing. Laser scanning microscopy was evaluated as being an excellent method to monitor the geometry and closure of the conduits over time. The used microneedle system was evaluated as suitable to enhance the transport of model drugs into the viable epidermis without bleeding and a short closure time of the conduits at the skin surface.

  3. Analysis of femtosecond laser assisted capsulotomy cutting edges and manual capsulorhexis using environmental scanning electron microscopy.

    Science.gov (United States)

    Serrao, Sebastiano; Lombardo, Giuseppe; Desiderio, Giovanni; Buratto, Lucio; Schiano-Lomoriello, Domenico; Pileri, Marco; Lombardo, Marco

    2014-01-01

    Purpose. To investigate the structure and irregularity of the capsulotomy cutting edges created by two femtosecond (FS) laser platforms in comparison with manual continuous circular capsulorhexis (CCC) using environmental scanning electron microscopy (eSEM). Methods. Ten anterior capsulotomies were obtained using two different FS laser cataract platforms (LenSx, n = 5, and Victus, n = 5). In addition, five manual CCC (n = 5) were obtained using a rhexis forceps. The specimens were imaged by eSEM (FEI Quanta 400, OR, USA). Objective metrics, which included the arithmetic mean deviation of the surface (Sa) and the root-mean-square deviation of the surface (Sq), were used to evaluate the irregularity of both the FS laser capsulotomies and the manual CCC cutting edges. Results. Several microirregularities were shown across the FS laser capsulotomy cutting edges. The edges of manually torn capsules were shown, by comparison of Sa and Sq values, to be smoother (P < 0.05) than the FS laser capsulotomy edges. Conclusions. Work is needed to understand whether the FS laser capsulotomy edge microirregularities, not seen in manual CCC, may act as focal points for the concentration of stress that would increase the risk of capsular tear during phacoemulsification as recently reported in the literature.

  4. Analysis of Femtosecond Laser Assisted Capsulotomy Cutting Edges and Manual Capsulorhexis Using Environmental Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Sebastiano Serrao

    2014-01-01

    Full Text Available Purpose. To investigate the structure and irregularity of the capsulotomy cutting edges created by two femtosecond (FS laser platforms in comparison with manual continuous circular capsulorhexis (CCC using environmental scanning electron microscopy (eSEM. Methods. Ten anterior capsulotomies were obtained using two different FS laser cataract platforms (LenSx, n=5, and Victus, n=5. In addition, five manual CCC (n=5 were obtained using a rhexis forceps. The specimens were imaged by eSEM (FEI Quanta 400, OR, USA. Objective metrics, which included the arithmetic mean deviation of the surface (Sa and the root-mean-square deviation of the surface (Sq, were used to evaluate the irregularity of both the FS laser capsulotomies and the manual CCC cutting edges. Results. Several microirregularities were shown across the FS laser capsulotomy cutting edges. The edges of manually torn capsules were shown, by comparison of Sa and Sq values, to be smoother (P<0.05 than the FS laser capsulotomy edges. Conclusions. Work is needed to understand whether the FS laser capsulotomy edge microirregularities, not seen in manual CCC, may act as focal points for the concentration of stress that would increase the risk of capsular tear during phacoemulsification as recently reported in the literature.

  5. Three-Dimensional Digital Documentation of Heritage Sites Using Terrestrial Laser Scanning and Unmanned Aerial Vehicle Photogrammetry

    Science.gov (United States)

    Jo, Y. H.; Kim, J. Y.

    2017-08-01

    Three-dimensional digital documentation is an important technique for the maintenance and monitoring of cultural heritage sites. This study focuses on the three-dimensional digital documentation of the Magoksa Temple, Republic of Korea, using a combination of terrestrial laser scanning and unmanned aerial vehicle (UAV) photogrammetry. Terrestrial laser scanning mostly acquired the vertical geometry of the buildings. In addition, the digital orthoimage produced by UAV photogrammetry had higher horizontal data acquisition rate than that produced by terrestrial laser scanning. Thus, the scanning and UAV photogrammetry were merged by matching 20 corresponding points and an absolute coordinate system was established using seven ground control points. The final, complete threedimensional shape had perfect horizontal and vertical geometries. This study demonstrates the potential of integrating terrestrial laser scanning and UAV photogrammetry for three-dimensional digital documentation. This new technique is expected to contribute to the three-dimensional digital documentation and spatial analysis of cultural heritage sites.

  6. Surface modification of ceramic and metallic alloy substrates by laser raster-scanning

    Science.gov (United States)

    Ramos Grez, Jorge Andres

    This work describes the feasibility of continuous wave laser-raster scan-processing under controlled atmospheric conditions as employed in three distinct surface modification processes: (a) surface roughness reduction of indirect-Selective Laser Sintered 420 martensitic stainless steel-40 wt. % bronze infiltrated surfaces; (b) Si-Cr-Hf-C coating consolidation over 3D carbon-carbon composites cylinders; (c) dendritic solidification structures of Mar-M 247 confined powder precursor grown from polycrystalline Alloy 718 substrates. A heat transfer model was developed to illustrate that the aspect ratio of the laser scanned pattern and the density of scanning lines play a significant role in determining peak surface temperature, heating and cooling rates and melt resident times. Comprehensive characterization of the surface of the processed specimens was performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), optical metallography, X-ray diffraction (XRD), and, in certain cases, tactile profilometry. In Process (a), it was observed that a 24% to 37% roughness Ra reduction could be accomplished from the as-received value of 2.50+/-0.10 microns for laser energy densities ranging from 350 to 500 J/cm2. In Process (b), complete reactive wetting of carbon-carbon composite cylinders surface was achieved by laser melting a Si-Cr-Hf-C slurry. Coatings showed good thermal stability at 1000°C in argon, and, when tested in air, a percent weight reduction rate of -6.5 wt.%/hr was achieved. A soda-glass overcoat applied over the coated specimens by conventional means revealed a percent weight reduction rate between -1.4 to -2.2 wt.%/hr. Finally, in Process (c), microstructure of the Mar-M 247 single layer deposits, 1 mm in height, grown on Alloy 718 polycrystalline sheets, resulted in a sound metallurgical bond, low porosity, and uniform thickness. Polycrystalline dendrites grew preferentially along the [001] direction from the substrate up to 400

  7. Functional characterization of planar sensors with active edges using laser and X-ray beam scans

    International Nuclear Information System (INIS)

    Povoli, M.; Bagolini, A.; Boscardin, M.; Dalla Betta, G.-F.; Giacomini, G.; Hasi, J.; Oh, A.; Zorzi, N.

    2013-01-01

    We report on the functional characterization of planar sensors with active edges fabricated at Fondazione Bruno Kessler (FBK), Trento, Italy. The measurements here reported were performed by means of laser and X-ray beam scans mainly focusing on the signal efficiency of the edge region of the devices. Results are very encouraging and show very good sensitivity up to few microns away from the device physical edge

  8. Functional characterization of planar sensors with active edges using laser and X-ray beam scans

    Energy Technology Data Exchange (ETDEWEB)

    Povoli, M., E-mail: povoli@disi.unitn.it [Dipartimento di Ingegneria e Scienza dell' Informazione, Università di Trento, Via Sommarive, 14, I-38123 Povo di Trento (Italy); INFN, Sezione di Padova (Gruppo Collegato di Trento),Via Sommarive, 14, I-38123 Povo di Trento (Italy); Bagolini, A.; Boscardin, M. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi (FBK-CMM), Via Sommarive, 18, I-38123 Povo di Trento (Italy); Dalla Betta, G.-F. [Dipartimento di Ingegneria e Scienza dell' Informazione, Università di Trento, Via Sommarive, 14, I-38123 Povo di Trento (Italy); INFN, Sezione di Padova (Gruppo Collegato di Trento),Via Sommarive, 14, I-38123 Povo di Trento (Italy); Giacomini, G. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi (FBK-CMM), Via Sommarive, 18, I-38123 Povo di Trento (Italy); Hasi, J. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025-7015 (United States); Oh, A. [The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Zorzi, N. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi (FBK-CMM), Via Sommarive, 18, I-38123 Povo di Trento (Italy)

    2013-08-01

    We report on the functional characterization of planar sensors with active edges fabricated at Fondazione Bruno Kessler (FBK), Trento, Italy. The measurements here reported were performed by means of laser and X-ray beam scans mainly focusing on the signal efficiency of the edge region of the devices. Results are very encouraging and show very good sensitivity up to few microns away from the device physical edge.

  9. Methods for studying biofilm formation: flow cells and confocal laser scanning microscopy

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2014-01-01

    In this chapter methods for growing and analyzing biofilms under hydrodynamic conditions in flow cells are described. Use of flow cells allows for direct microscopic investigation of biofilm formation. The flow in these chambers is essentially laminar, which means that the biofilms can be grown u......, inoculation of the flow cells, running of the system, confocal laser scanning microscopy and image analysis, and disassembly and cleaning of the system....

  10. Adaptive optics scanning laser ophthalmoscopy in fundus imaging, a review and update

    OpenAIRE

    Zhang, Bing; Li, Ni; Kang, Jie; He, Yi; Chen, Xiao-Ming

    2017-01-01

    Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has been a promising technique in funds imaging with growing popularity. This review firstly gives a brief history of adaptive optics (AO) and AO-SLO. Then it compares AO-SLO with conventional imaging methods (fundus fluorescein angiography, fundus autofluorescence, indocyanine green angiography and optical coherence tomography) and other AO techniques (adaptive optics flood-illumination ophthalmoscopy and adaptive optics optical coherenc...

  11. Close-range laser scanning in forests: towards physically based semantics across scales.

    Science.gov (United States)

    Morsdorf, F; Kükenbrink, D; Schneider, F D; Abegg, M; Schaepman, M E

    2018-04-06

    Laser scanning with its unique measurement concept holds the potential to revolutionize the way we assess and quantify three-dimensional vegetation structure. Modern laser systems used at close range, be it on terrestrial, mobile or unmanned aerial platforms, provide dense and accurate three-dimensional data whose information just waits to be harvested. However, the transformation of such data to information is not as straightforward as for airborne and space-borne approaches, where typically empirical models are built using ground truth of target variables. Simpler variables, such as diameter at breast height, can be readily derived and validated. More complex variables, e.g. leaf area index, need a thorough understanding and consideration of the physical particularities of the measurement process and semantic labelling of the point cloud. Quantified structural models provide a framework for such labelling by deriving stem and branch architecture, a basis for many of the more complex structural variables. The physical information of the laser scanning process is still underused and we show how it could play a vital role in conjunction with three-dimensional radiative transfer models to shape the information retrieval methods of the future. Using such a combined forward and physically based approach will make methods robust and transferable. In addition, it avoids replacing observer bias from field inventories with instrument bias from different laser instruments. Still, an intensive dialogue with the users of the derived information is mandatory to potentially re-design structural concepts and variables so that they profit most of the rich data that close-range laser scanning provides.

  12. STRUCTURED-LIGHT BASED 3D LASER SCANNING OF SEMI-SUBMERGED STRUCTURES

    Directory of Open Access Journals (Sweden)

    J. van der Lucht

    2018-05-01

    Full Text Available In this work we look at 3D acquisition of semi-submerged structures with a triangulation based underwater laser scanning system. The motivation is that we want to simultaneously capture data above and below water to create a consistent model without any gaps. The employed structured light scanner consist of a machine vision camera and a green line laser. In order to reconstruct precise surface models of the object it is necessary to model and correct for the refraction of the laser line and camera rays at the water-air boundary. We derive a geometric model for the refraction at the air-water interface and propose a method for correcting the scans. Furthermore, we show how the water surface is directly estimated from sensor data. The approach is verified using scans captured with an industrial manipulator to achieve reproducible scanner trajectories with different incident angles. We show that the proposed method is effective for refractive correction and that it can be applied directly to the raw sensor data without requiring any external markers or targets.

  13. Structured-Light Based 3d Laser Scanning of Semi-Submerged Structures

    Science.gov (United States)

    van der Lucht, J.; Bleier, M.; Leutert, F.; Schilling, K.; Nüchter, A.

    2018-05-01

    In this work we look at 3D acquisition of semi-submerged structures with a triangulation based underwater laser scanning system. The motivation is that we want to simultaneously capture data above and below water to create a consistent model without any gaps. The employed structured light scanner consist of a machine vision camera and a green line laser. In order to reconstruct precise surface models of the object it is necessary to model and correct for the refraction of the laser line and camera rays at the water-air boundary. We derive a geometric model for the refraction at the air-water interface and propose a method for correcting the scans. Furthermore, we show how the water surface is directly estimated from sensor data. The approach is verified using scans captured with an industrial manipulator to achieve reproducible scanner trajectories with different incident angles. We show that the proposed method is effective for refractive correction and that it can be applied directly to the raw sensor data without requiring any external markers or targets.

  14. Atomic force microscopy and confocal laser scanning microscopy on the cytoskeleton of permeabilised and embedded cells

    International Nuclear Information System (INIS)

    Meller, Karl; Theiss, Carsten

    2006-01-01

    We describe a technical method of cell permeabilisation and embedding to study the organisation and distribution of intracellular proteins with aid of atomic force microscopy and confocal laser scanning microscopy in identical areas. While confocal laser scanning microscopy is useful for the identification of certain proteins subsequent labelling with markers or antibodies, atomic force microscopy allows the observation of macromolecular structures in fixed and living cells. To demonstrate the field of application of this preparatory technique, cells were permeabilised, fixed, and the actin cytoskeleton was stained with phalloidin-rhodamine. Confocal laser scanning microscopy was used to show the organisation of these microfilaments, e.g. geodesic dome structures. Thereafter, cells were embedded in Durcupan water-soluble resin, followed by UV-polymerisation of resin at 4 o C. This procedure allowed intracellular visualisation of the cell nucleus or cytoskeletal elements by atomic force microscopy, for instance to analyse the globular organisation of actin filaments. Therefore, this method offers a great potential to combine both microscopy techniques in order to understand and interpret intracellular protein relations, for example, the biochemical and morphological interaction of the cytoskeleton

  15. Geometric validation of a mobile laser scanning system for urban applications

    Science.gov (United States)

    Guan, Haiyan; Li, Jonathan; Yu, Yongtao; Liu, Yan

    2016-03-01

    Mobile laser scanning (MLS) technologies have been actively studied and implemented over the past decade, as their application fields are rapidly expanding and extending beyond conventional topographic mapping. Trimble's MX-8, as one of the MLS systems in the current market, generates rich survey-grade laser and image data for urban surveying. The objective of this study is to evaluate whether Trimble MX-8 MLS data satisfies the accuracy requirements of urban surveying. According to the formula of geo-referencing, accuracies of navigation solution and laser scanner determines the accuracy of the collected LiDAR point clouds. Two test sites were selected to test the performance of Trimble MX-8. Those extensive tests confirm that Trimble MX-8 offers a very promising tool to survey complex urban areas.

  16. Improving quality of laser scanning data acquisition through calibrated amplitude and pulse deviation measurement

    Science.gov (United States)

    Pfennigbauer, Martin; Ullrich, Andreas

    2010-04-01

    Newest developments in laser scanner technologies put surveyors in the position to comply with the ever increasing demand of high-speed, high-accuracy, and highly reliable data acquisition from terrestrial, mobile, and airborne platforms. Echo digitization in pulsed time-of-flight laser ranging has demonstrated its superior performance in the field of bathymetry and airborne laser scanning for more than a decade, however at the cost of somewhat time consuming off line post processing. State-of-the-art online waveform processing as implemented in RIEGL's V-Line not only saves users post-processing time to obtain true 3D point clouds, it also adds the assets of calibrated amplitude and reflectance measurement for data classification and pulse deviation determination for effective and reliable data validation. We present results from data acquisitions in different complex target situations.

  17. Innovation and optimization of a method of pump-probe polarimetry with pulsed laser beams in view of a precise measurement of parity violation in atomic cesium; Innovation et optimisation d'une methode de polarimetrie pompe-sonde avec des faisceaux laser impulsionnels en vue d'une mesure precise de violation de la parite dans l'atome de cesium

    Energy Technology Data Exchange (ETDEWEB)

    Chauvat, D

    1997-10-15

    While Parity Violation (PV) experiments on highly forbidden transitions have been using detection of fluorescence signals; our experiment uses a pump-probe scheme to detect the PV signal directly on a transmitted probe beam. A pulsed laser beam of linear polarisation {epsilon}{sub 1} excites the atoms on the 6S-7S cesium transition in a colinear electric field E || k(ex). The probe beam (k(pr) || k(ex)) of linear polarisation {epsilon}{sub 2} tuned to the transition 7S-6P(3/2) is amplified. The small asymmetry ({approx} 10{sup -6}) in the gain that depends on the handedness of the tri-hedron (E, {epsilon}{sub 1}, {epsilon}{sub 2}) is the manifestation of the PV effect. This is measured as an E-odd apparent rotation of the plane of polarization of the probe beam; using balanced mode polarimetry. New criteria of selection have been devised, that allow us to distinguish the true PV-signal against fake rotations due to electromagnetic interferences, geometrical effects, polarization imperfections, or stray transverse electric and magnetic fields. These selection criteria exploit the symmetry of the PV-rotation - linear dichroism - and the revolution symmetry of the experiment. Using these criteria it is not only possible to reject fake signals, but also to elucidate the underlying physical mechanisms and to measure the relevant defects of the apparatus. The present signal-to-noise ratio allows embarking in PV measurements to reach the 10% statistical accuracy. A 1% measurement still requires improvements. Two methods have been demonstrated. The first one exploits the amplification of the asymmetry at high gain - one major advantage provided by our detection method based on stimulated emission. The second method uses both a much higher incident intensity and a special dichroic component which magnifies tiny polarization rotations. (author)

  18. Modeling Main Body of Overcrossing Bridge Based on Vehicle-Borne Laser Scanning Data

    Science.gov (United States)

    Chen, X.; Chen, M.; Wei, Z.; Zhong, R.

    2017-09-01

    Vehicle-borne laser scanning (VBLS) is widely used to collect urban data for various mapping and modelling systems. This paper proposes a strategy of feature extraction and 3d model reconstruction for main body of overcrossing bridges based on VBLS point clouds. As the bridges usually have a large span, and the clouds data is often affected by obstacles, we have to use round-trip cloud data to avoid missing part. To begin with, pick out the cloud of the bridge body by an interactive clip-box, and group points by scan-line, then sort the points by scanning angle on each scan line. Since the position under the vehicle have a fixed scan-angle, a virtual path can be obtained. Secondly, extract horizontal line segments perpendicular to the virtual path along adjacent scan-lines, and then cluster line segments into long line-strings, which represent the top and bottom edge. Finally, regularize the line-strings and build 3d surface model of the bridge body. Experimental studies have demonstrated its efficiency and accuracy in case of building bridge model. Modelling the stairs at the both end of the bridge will be the direction of the next step.

  19. MODELING MAIN BODY OF OVERCROSSING BRIDGE BASED ON VEHICLE-BORNE LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    X. Chen

    2017-09-01

    Full Text Available Vehicle-borne laser scanning (VBLS is widely used to collect urban data for various mapping and modelling systems. This paper proposes a strategy of feature extraction and 3d model reconstruction for main body of overcrossing bridges based on VBLS point clouds. As the bridges usually have a large span, and the clouds data is often affected by obstacles, we have to use round-trip cloud data to avoid missing part. To begin with, pick out the cloud of the bridge body by an interactive clip-box, and group points by scan-line, then sort the points by scanning angle on each scan line. Since the position under the vehicle have a fixed scan-angle, a virtual path can be obtained. Secondly, extract horizontal line segments perpendicular to the virtual path along adjacent scan-lines, and then cluster line segments into long line-strings, which represent the top and bottom edge. Finally, regularize the line-strings and build 3d surface model of the bridge body. Experimental studies have demonstrated its efficiency and accuracy in case of building bridge model. Modelling the stairs at the both end of the bridge will be the direction of the next step.

  20. Comparison of tissue damage caused by various laser systems with tissue tolerable plasma by light and laser scan microscopy

    International Nuclear Information System (INIS)

    Vandersee, Staffan; Lademann, Jürgen; Richter, Heike; Patzelt, Alexa; Lange-Asschenfeldt, Bernhard

    2013-01-01

    Tissue tolerable plasma (TTP) represents a novel therapeutic method with promising capabilities in the field of dermatological interventions, in particular disinfection but also wound antisepsis and regeneration. The energy transfer by plasma into living tissue is not easily educible, as a variety of features such as the medium’s actual molecule-stream, the ions, electrons and free radicals involved, as well as the emission of ultraviolet, visible and infrared light contribute to its increasingly well characterized effects. Thus, relating possible adversary effects, especially of prolonged exposure to a single component of the plasma’s mode of action, is difficult. Until now, severe adverse events connected to plasma exposure have not been reported when conducted according to existing therapeutic protocols. In this study, we have compared the tissue damage-potential of CO 2 and dye lasers with TTP in a porcine model. After exposure of pig ear skin to the three treatment modalities, all specimens were examined histologically and by means of laser scan microscopy (LSM). Light microscopical tissue damage could only be shown in the case of the CO 2 laser, whereas dye laser and plasma treatment resulted in no detectable impairment of the specimens. In the case of TTP, LSM examination revealed only an impairment of the uppermost corneal layers of the skin, thus stressing its safety when used in vivo. (letter)

  1. Automated detection of delamination and disbond from wavefield images obtained using a scanning laser vibrometer

    International Nuclear Information System (INIS)

    Sohn, H; Yang, J Y; Dutta, D; DeSimio, M; Olson, S; Swenson, E

    2011-01-01

    The paper presents signal and image processing algorithms to automatically detect delamination and disbond in composite plates from wavefield images obtained using a scanning laser Doppler vibrometer (LDV). Lamb waves are excited by a lead zirconate titanate transducer (PZT) mounted on the surface of a composite plate, and the out-of-plane velocity field is measured using an LDV. From the scanned time signals, wavefield images are constructed and processed to study the interaction of Lamb waves with hidden delaminations and disbonds. In particular, the frequency–wavenumber (f–k) domain filter and the Laplacian image filter are used to enhance the visibility of defects in the scanned images. Thereafter, a statistical cluster detection algorithm is used to identify the defect location and distinguish damaged specimens from undamaged ones

  2. New methods for precision Moeller polarimetry*

    International Nuclear Information System (INIS)

    Gaskell, D.; Meekins, D.G.; Yan, C.

    2007-01-01

    Precision electron beam polarimetry is becoming increasingly important as parity violation experiments attempt to probe the frontiers of the standard model. In the few GeV regime, Moeller polarimetry is well suited to high-precision measurements, however is generally limited to use at relatively low beam currents (<10 μA). We present a novel technique that will enable precision Moeller polarimetry at very large currents, up to 100 μA. (orig.)

  3. Three-Dimensional Geometry of Collagenous Tissues by Second Harmonic Polarimetry.

    Science.gov (United States)

    Reiser, Karen; Stoller, Patrick; Knoesen, André

    2017-06-01

    Collagen is a biological macromolecule capable of second harmonic generation, allowing label-free detection in tissues; in addition, molecular orientation can be determined from the polarization dependence of the second harmonic signal. Previously we reported that in-plane orientation of collagen fibrils could be determined by modulating the polarization angle of the laser during scanning. We have now extended this method so that out-of-plane orientation angles can be determined at the same time, allowing visualization of the 3-dimensional structure of collagenous tissues. This approach offers advantages compared with other methods for determining out-of-plane orientation. First, the orientation angles are directly calculated from the polarimetry data obtained in a single scan, while other reported methods require data from multiple scans, use of iterative optimization methods, application of fitting algorithms, or extensive post-optical processing. Second, our method does not require highly specialized instrumentation, and thus can be adapted for use in almost any nonlinear optical microscopy setup. It is suitable for both basic and clinical applications. We present three-dimensional images of structurally complex collagenous tissues that illustrate the power of such 3-dimensional analyses to reveal the architecture of biological structures.

  4. Effective Data-Driven Calibration for a Galvanometric Laser Scanning System Using Binocular Stereo Vision.

    Science.gov (United States)

    Tu, Junchao; Zhang, Liyan

    2018-01-12

    A new solution to the problem of galvanometric laser scanning (GLS) system calibration is presented. Under the machine learning framework, we build a single-hidden layer feedforward neural network (SLFN)to represent the GLS system, which takes the digital control signal at the drives of the GLS system as input and the space vector of the corresponding outgoing laser beam as output. The training data set is obtained with the aid of a moving mechanism and a binocular stereo system. The parameters of the SLFN are efficiently solved in a closed form by using extreme learning machine (ELM). By quantitatively analyzing the regression precision with respective to the number of hidden neurons in the SLFN, we demonstrate that the proper number of hidden neurons can be safely chosen from a broad interval to guarantee good generalization performance. Compared to the traditional model-driven calibration, the proposed calibration method does not need a complex modeling process and is more accurate and stable. As the output of the network is the space vectors of the outgoing laser beams, it costs much less training time and can provide a uniform solution to both laser projection and 3D-reconstruction, in contrast with the existing data-driven calibration method which only works for the laser triangulation problem. Calibration experiment, projection experiment and 3D reconstruction experiment are respectively conducted to test the proposed method, and good results are obtained.

  5. Effective Data-Driven Calibration for a Galvanometric Laser Scanning System Using Binocular Stereo Vision

    Directory of Open Access Journals (Sweden)

    Junchao Tu

    2018-01-01

    Full Text Available A new solution to the problem of galvanometric laser scanning (GLS system calibration is presented. Under the machine learning framework, we build a single-hidden layer feedforward neural network (SLFN)to represent the GLS system, which takes the digital control signal at the drives of the GLS system as input and the space vector of the corresponding outgoing laser beam as output. The training data set is obtained with the aid of a moving mechanism and a binocular stereo system. The parameters of the SLFN are efficiently solved in a closed form by using extreme learning machine (ELM. By quantitatively analyzing the regression precision with respective to the number of hidden neurons in the SLFN, we demonstrate that the proper number of hidden neurons can be safely chosen from a broad interval to guarantee good generalization performance. Compared to the traditional model-driven calibration, the proposed calibration method does not need a complex modeling process and is more accurate and stable. As the output of the network is the space vectors of the outgoing laser beams, it costs much less training time and can provide a uniform solution to both laser projection and 3D-reconstruction, in contrast with the existing data-driven calibration method which only works for the laser triangulation problem. Calibration experiment, projection experiment and 3D reconstruction experiment are respectively conducted to test the proposed method, and good results are obtained.

  6. MICROSTRUCTURING OF SILICON SINGLE CRYSTALS BY FIBER LASER IN HIGH-SPEED SCANNING MODE

    Directory of Open Access Journals (Sweden)

    T. A. Trifonova

    2015-11-01

    Full Text Available Subject of Study. The surface structure of the silicon wafers (substrate with a thermally grown silicon dioxide on the surface (of SiO2/Si is studied after irradiation by pulse fiber laser of ILI-1-20 type. The main requirements for exposure modes of the system are: the preservation of the integrity of the film of silicon dioxide in the process of microstructuring and the absence of interference of surrounding irradiated areas of the substrate. Method. Studies were carried out on silicon wafers KEF-4,5 oriented in the crystallographic plane (111 with the source (natural silicon dioxide (SiO2 with thickness of about 4 nm, and SiO2 with 40 nm and 150 nm thickness, grown by thermal oxidation in moist oxygen. Also, wafers KHB-10 oriented in the plane (100 with 500 nm thickness of thermal oxide were investigated. Irradiation of SiO2/Si system was produced by laser complex based on ytterbium fiber pulse laser ILI-1-20. Nominal output power of the laser was 20 W, and the laser wavelength was λ = 1062 nm. Irradiation was carried out by a focused beam spot with a diameter of 25 microns and a pulse repetition rate of 99 kHz. The samples with 150 nm and 40 nm thickness of SiO2 were irradiated at a power density equal to 1,2·102 W/cm2, and the samples of SiO2 with 500 nm thickness were irradiated at a power density equal to 2,0·102 W/cm2. Scanning was performed using a two-axis Coordinate Scanning Device based on VM2500+ drives with control via a PC with the software package "SinMarkTM." Only one scan line was used at the maximum speed of the beam equal to 8750 mm/s. Morphology control of the irradiated samples was conducted by an optical microscope ZeissA1M with high-resolution CCD array. A scanning probe microscope Nanoedicator of the NT-MDT company was used for structural measurements. Main Results. It has been shown that at a single exposure of high-frequency pulsed laser radiation on SiO2/Si system, with maintaining the integrity of the SiO2 film

  7. Selective Removal of Residual Orthodontic Composite Using a Rapidly Scanned Carbon Dioxide Laser with Spectral Feedback

    Science.gov (United States)

    Hirasuna, Krista

    Background and Objective: Excessive heat accumulation within the tooth, incomplete removal of composite, and variable damage to the enamel are shortcomings of using conventional burs to remove residual orthodontic composite after debonding fixed appliances. The objective of this study was to determine if composite could be selectively removed from the enamel surface using a rapidly scanned carbon dioxide laser controlled by spectral feedback. Materials and Methods: A carbon dioxide laser operating at a wavelength of 9.3 microm with a pulse duration of 10-15 micros and a pulse repetition rate of ˜ 200 Hz was used to selectively remove composite from the buccal surfaces of 21 extracted teeth. GrenGloo(TM) composite was used to better visualize residual composite and the amount of enamel lost was measured with optical microscopy. A spectral feedback system utilizing a miniature spectrometer was used to control the laser scanning system. Pulpal temperature measurements were performed during composite removal to determine if there was excessive heat accumulation. Results: The amount of enamel lost averaged 22.7microm +/- 8.9 and 25.3 microm +/- 9.4 for removal at 3.8 and 4.2 J/cm2, respectively. An average maximum temperature rise of 1.9°C +/- 1.5 was recorded, with no teeth approaching the critical value of 5.5°C. The average time of composite removal was 19.3 +/- 4.1 seconds. Conclusions: Residual orthodontic composite can be rapidly removed from the tooth surface using a rapidly scanned CO2 laser with spectral feedback, with minimal temperature rise within the pulp and with minimal damage to the underlying enamel surface.

  8. FROM THE CONTINUOS TO THE DISCRETE MODEL: A LASER SCANNING APPLICATION TO CONSERVATION PROJECTS

    Directory of Open Access Journals (Sweden)

    A. Cardaci

    2012-09-01

    Full Text Available This paper aims to demonstrate the usage of laser scanning (in particular through a methodology based on the integrated use of the software "FARO© Scene" and "GEXCEL JRC-3D Reconstructor" as a valid alternative to traditional surveying techniques, especially when finalized to the restoration and conservation repair of historical buildings. The need to recreate the complex and often irregular shapes of the ancient architecture, by acting quickly and also being accurate, as well as the subsequent implementation of FEM (Finite Element Method for structural analysis, have made nowadays the laser scanning survey a very useful technique. The point cloud obtained by laser scanning can be a flexible tool for every need; not a finished product, but a huge database from which it is possible to extract different information at different times. The use of numerical methods in data processing allows wide opportunities of further investigations starting from the fitting equations. The numerical model lends by itself to the possibility of usage in many applications, such as modelization and structure analysis software. This paper presents the case study of the Church of the Assumption and Saint Michael the Archangel, located in Borgo di Terzo (Italy, a magnificent 18th century's building that presented several structural problems like as the overturning of the façade, the cracking of part of the vaulted ceiling. The survey, carried out by laser scanner (FARO© Photon 120 allowed the reconstruction of the exact geometry of the church, offering the basis for performing structural analysis supported by a realistic model (and not an idealized regular one, useful also in the design of repair interventions.

  9. Novel 755-nm diode laser vs. conventional 755-nm scanned alexandrite laser: Side-by-side comparison pilot study for thorax and axillary hair removal.

    Science.gov (United States)

    Paasch, Uwe; Wagner, Justinus A; Paasch, Hartmut W

    2015-01-01

    Alexandrite (755 nm) and diode lasers (800-810 nm) are commonly used for hair removal. The alexandrite laser technology is somewhat cumbersome whereas new diode lasers are more robust. Recently, alexandrite-like 755 nm wavelength diodes became available. To compare the efficacy, tolerability, and subject satisfaction of a 755 nm diode laser operated in conventional (HR) and non-conventional in-motion (SHR) modes with a conventional scanned alexandrite 755 nm laser for chest and axillary hair removal. A prospective, single-center, proof of principle study was designed to evaluate the safety, efficacy and handling of a 755 nm diode laser system in comparison to a standard alexandrite 755 nm scanning hair removal laser. The new 755 nm diode is suitable to be used in SHR and HR mode and has been tested for its safety, efficacy and handling in a volunteer with success. Overall, both systems showed a high efficacy in hair reduction (88.8% 755 nm diode laser vs. 77.7% 755 nm alexandrite laser). Also, during the study period, no severe adverse effects were reported. The new 755 nm diode laser is as effective and safe as the traditional 755 nm alexandrite laser. Additionally, treatment with the 755 nm diode laser with HR and SHR modes was found to be less painful.

  10. Scanning Laser Ophthalmoscope Measurement of Local Fundus Reflectance and Autofluorescence Changes Arising from Rhodopsin Bleaching and Regeneration

    OpenAIRE

    Morgan, Jessica I. W.; Pugh, Edward N.

    2013-01-01

    Rhodopsin was measured locally in the retina with a widely available, dual wavelength scanning laser ophthalmoscope that does not require pupil dilation. Increased autofluorescence attendant bleaching arises largely from transient removal of rhodopsin's screening of autofluorescent fluorochromes.

  11. 3D camera assisted fully automated calibration of scanning laser Doppler vibrometers

    International Nuclear Information System (INIS)

    Sels, Seppe; Ribbens, Bart; Mertens, Luc; Vanlanduit, Steve

    2016-01-01

    Scanning laser Doppler vibrometers (LDV) are used to measure full-field vibration shapes of products and structures. In most commercially available scanning laser Doppler vibrometer systems the user manually draws a grid of measurement locations on a 2D camera image of the product. The determination of the correct physical measurement locations can be a time consuming and diffcult task. In this paper we present a new methodology for product testing and quality control that integrates 3D imaging techniques with vibration measurements. This procedure allows to test prototypes in a shorter period because physical measurements locations will be located automatically. The proposed methodology uses a 3D time-of-flight camera to measure the location and orientation of the test-object. The 3D image of the time-of-flight camera is then matched with the 3D-CAD model of the object in which measurement locations are pre-defined. A time of flight camera operates strictly in the near infrared spectrum. To improve the signal to noise ratio in the time-of-flight measurement, a time-of-flight camera uses a band filter. As a result of this filter, the laser spot of most laser vibrometers is invisible in the time-of-flight image. Therefore a 2D RGB-camera is used to find the laser-spot of the vibrometer. The laser spot is matched to the 3D image obtained by the time-of-flight camera. Next an automatic calibration procedure is used to aim the laser at the (pre)defined locations. Another benefit from this methodology is that it incorporates automatic mapping between a CAD model and the vibration measurements. This mapping can be used to visualize measurements directly on a 3D CAD model. Secondly the orientation of the CAD model is known with respect to the laser beam. This information can be used to find the direction of the measured vibration relatively to the surface of the object. With this direction, the vibration measurements can be compared more precisely with numerical

  12. 3D camera assisted fully automated calibration of scanning laser Doppler vibrometers

    Energy Technology Data Exchange (ETDEWEB)

    Sels, Seppe, E-mail: Seppe.Sels@uantwerpen.be; Ribbens, Bart; Mertens, Luc; Vanlanduit, Steve [Op3Mech Research Group, University of Antwerp, Salesianenlaan 90, 2660 Antwerp (Belgium)

    2016-06-28

    Scanning laser Doppler vibrometers (LDV) are used to measure full-field vibration shapes of products and structures. In most commercially available scanning laser Doppler vibrometer systems the user manually draws a grid of measurement locations on a 2D camera image of the product. The determination of the correct physical measurement locations can be a time consuming and diffcult task. In this paper we present a new methodology for product testing and quality control that integrates 3D imaging techniques with vibration measurements. This procedure allows to test prototypes in a shorter period because physical measurements locations will be located automatically. The proposed methodology uses a 3D time-of-flight camera to measure the location and orientation of the test-object. The 3D image of the time-of-flight camera is then matched with the 3D-CAD model of the object in which measurement locations are pre-defined. A time of flight camera operates strictly in the near infrared spectrum. To improve the signal to noise ratio in the time-of-flight measurement, a time-of-flight camera uses a band filter. As a result of this filter, the laser spot of most laser vibrometers is invisible in the time-of-flight image. Therefore a 2D RGB-camera is used to find the laser-spot of the vibrometer. The laser spot is matched to the 3D image obtained by the time-of-flight camera. Next an automatic calibration procedure is used to aim the laser at the (pre)defined locations. Another benefit from this methodology is that it incorporates automatic mapping between a CAD model and the vibration measurements. This mapping can be used to visualize measurements directly on a 3D CAD model. Secondly the orientation of the CAD model is known with respect to the laser beam. This information can be used to find the direction of the measured vibration relatively to the surface of the object. With this direction, the vibration measurements can be compared more precisely with numerical

  13. Early intraocular pressure change after peripheral iridotomy with ultralow fluence pattern scanning laser and Nd:YAG laser in primary angle-closure suspect: Kowloon East Pattern Scanning Laser Study Report No. 3.

    Science.gov (United States)

    Chan, Jeffrey Chi Wang; Choy, Bonnie Nga Kwan; Chan, Orlando Chia Chieh; Li, Kenneth Kai Wang

    2018-02-01

    Our purpose was to assess the early intraocular pressure (IOP) changes of ultralow fluence laser iridotomy using pattern scanning laser followed by neodymium:yttrium-aluminum-gamet (Nd:YAG) laser. This is a prospective interventional study. Thirty-three eyes of 33 adult Chinese primary angle-closure suspect subjects were recruited for prophylactic laser peripheral iridotomy. Sequential laser peripheral iridotomy was performed using pattern scanning laser followed by Nd:YAG laser. Visual acuity (VA) and IOP were measured before treatment, at 1 h, 1 day, 1 week, 1 month, 3 months and 6 months after laser. Laser energy used and complications were documented. Corneal endothelial cell count was examined at baseline and 6 months. Patency of the iridotomy was assessed at each follow-up visit. All subjects achieved patent iridotomy in a single session. The mean energy used was 0.335+/-0.088 J for the pattern scanning laser, and 4.767+/-5.780 mJ for the Nd:YAG laser. The total mean energy was 0.339+/-0.089 J. None of the eyes developed a clinically significant IOP spike (≥ 8 mmHg) at 1 h and 1 day after laser use. Only four eyes developed higher IOP at 1 h and all were ≤3 mmHg compared to baseline. The mean IOP was 13.8+/-2.5 mmHg at 1 h and 11.5+/-2.2 mmHg at 1 day, both were significantly lower than baseline (15.8+/-2.1 mmHg) (P laser compared to baseline (0.23 vs 0.26). There was also no statistically significant difference in mean VA at other follow-up visits compared to baseline. Peripheral iridotomy closure was encountered in two (6.1%) eyes, one at 1 month and another at 6 months follow-up. There were no complications including hyphema, peripheral anterior synechia formation nor prolonged inflammation throughout the follow-up period. There was no significant loss in corneal endothelial cell counts at 6 months (2255+/-490) compared to baseline (2303+/-386) (P = 0.347). Sequential LPI using an ultralow fluence pattern scanning laser

  14. Intradermal indocyanine green for in vivo fluorescence laser scanning microscopy of human skin: a pilot study.

    Directory of Open Access Journals (Sweden)

    Constanze Jonak

    Full Text Available BACKGROUND: In clinical diagnostics, as well as in routine dermatology, the increased need for non-invasive diagnosis is currently satisfied by reflectance laser scanning microscopy. However, this technique has some limitations as it relies solely on differences in the reflection properties of epidermal and dermal structures. To date, the superior method of fluorescence laser scanning microscopy is not generally applied in dermatology and predominantly restricted to fluorescein as fluorescent tracer, which has a number of limitations. Therefore, we searched for an alternative fluorophore matching a novel skin imaging device to advance this promising diagnostic approach. METHODOLOGY/PRINCIPAL FINDINGS: Using a Vivascope®-1500 Multilaser microscope, we found that the fluorophore Indocyanine-Green (ICG is well suited as a fluorescent marker for skin imaging in vivo after intradermal injection. ICG is one of few fluorescent dyes approved for use in humans. Its fluorescence properties are compatible with the application of a near-infrared laser, which penetrates deeper into the tissue than the standard 488 nm laser for fluorescein. ICG-fluorescence turned out to be much more stable than fluorescein in vivo, persisting for more than 48 hours without significant photobleaching whereas fluorescein fades within 2 hours. The well-defined intercellular staining pattern of ICG allows automated cell-recognition algorithms, which we accomplished with the free software CellProfiler, providing the possibility of quantitative high-content imaging. Furthermore, we demonstrate the superiority of ICG-based fluorescence microscopy for selected skin pathologies, including dermal nevi, irritant contact dermatitis and necrotic skin. CONCLUSIONS/SIGNIFICANCE: Our results introduce a novel in vivo skin imaging technique using ICG, which delivers a stable intercellular fluorescence signal ideal for morphological assessment down to sub-cellular detail. The application of

  15. Fabrication of SLM NiTi Shape Memory Alloy via Repetitive Laser Scanning

    Science.gov (United States)

    Khoo, Zhong Xun; Liu, Yong; Low, Zhi Hong; An, Jia; Chua, Chee Kai; Leong, Kah Fai

    2018-01-01

    Additive manufacturing has the potential to overcome the poor machinability of NiTi shape-memory alloy in fabricating smart structures of complex geometry. In recent years, a number of research activities on selective laser melting (SLM) of NiTi have been carried out to explore the optimal parameters for producing SLM NiTi with the desired phase transformation characteristics and shape-memory properties. Different effects of energy density and processing parameters on the properties of SLM NiTi were reported. In this research, a new approach—repetitive laser scanning—is introduced to meet these objectives as well. The results suggested that the laser absorptivity and heat conductivity of materials before and after the first scan significantly influence the final properties of SLM NiTi. With carefully controlled repetitive scanning process, the fabricated samples have demonstrated shape-memory effect of as high as 5.11% (with an average value of 4.61%) and exhibited comparable transformation characteristics as the NiTi powder used. These results suggest the potential for fabricating complex NiTi structures with similar properties to that of the conventionally produced NiTi parts.

  16. Scanning mid-IR laser apparatus with eye tracking for refractive surgery

    Science.gov (United States)

    Telfair, William B.; Yoder, Paul R., Jr.; Bekker, Carsten; Hoffman, Hanna J.; Jensen, Eric F.

    1999-06-01

    A robust, real-time, dynamic eye tracker has been integrated with the short pulse mid-infrared laser scanning delivery system previously described. This system employs a Q- switched Nd:YAG laser pumped optical parametric oscillator operating at 2.94 micrometers. Previous ablation studies on human cadaver eyes and in-vivo cat eyes demonstrated very smooth ablations with extremely low damage levels similar to results with an excimer. A 4-month healing study with cats indicated no adverse healing effects. In order to treat human eyes, the tracker is required because the eyes move during the procedure due to both voluntary and involuntary motions such as breathing, heartbeat, drift, loss of fixation, saccades and microsaccades. Eye tracking techniques from the literature were compared. A limbus tracking system was best for this application. Temporal and spectral filtering techniques were implemented to reduce tracking errors, reject stray light, and increase signal to noise ratio. The expanded-capability system (IRVision AccuScan 2000 Laser System) has been tested in the lab on simulated eye targets, glass eyes, cadaver eyes, and live human subjects. Circular targets ranging from 10-mm to 14-mm diameter were successfully tracked. The tracker performed beyond expectations while the system performed myopic photorefractive keratectomy procedures on several legally blind human subjects.

  17. High Heat Flux Interactions and Tritium Removal from Plasma Facing Components by a Scanning Laser

    International Nuclear Information System (INIS)

    Skinner, C.H.; Gentile, C.A.; Hassanein, A.

    2002-01-01

    A new technique for studying high heat flux interactions with plasma facing components is presented. The beam from a continuous wave 300 W neodymium laser was focused to 80 W/mm2 and scanned at high speed over the surface of carbon tiles. These tiles were previously used in the TFTR [Tokamak Fusion Test Reactor] inner limiter and have a surface layer of amorphous hydrogenated carbon that was codeposited during plasma operations. Laser scanning released up to 84% of the codeposited tritium. The temperature rise of the codeposit on the tiles was significantly higher than that of the manufactured material. In one experiment, the codeposit surface temperature rose to 1,770 C while for the same conditions, the manufactured surface increased to only 1,080 C. The peak temperature did not follow the usual square-root dependence on heat pulse duration. Durations of order 100 ms resulted in brittle destruction and material loss from the surface, while a duration of approximately 10 ms showed minimal change. A digital microscope imaged the codeposit before, during, and after the interaction with the laser and revealed hot spots on a 100-micron scale. These results will be compared to analytic modeling and are relevant to the response of plasma facing components to disruptions and vertical displacement events (VDEs) in next-step magnetic fusion devices

  18. Additive Manufacturing of Nickel-Base Superalloy IN100 Through Scanning Laser Epitaxy

    Science.gov (United States)

    Basak, Amrita; Das, Suman

    2018-01-01

    Scanning laser epitaxy (SLE) is a laser powder bed fusion (LPBF)-based additive manufacturing process that uses a high-power laser to consolidate metal powders facilitating the fabrication of three-dimensional objects. In the present study, SLE is used to produce samples of IN100, a high-γ' non-weldable nickel-base superalloy on similar chemistry substrates. A thorough analysis is performed using various advanced material characterization techniques such as high-resolution optical microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and Vickers microhardness measurements to characterize and compare the quality of the SLE-fabricated IN100 deposits with the investment cast IN100 substrates. The results show that the IN100 deposits have a finer γ/γ' microstructure, weaker elemental segregation, and higher microhardness compared with the substrate. Through this study, it is demonstrated that the SLE process has tremendous potential in the repair and manufacture of gas turbine hot-section components.

  19. Fabrication of SLM NiTi Shape Memory Alloy via Repetitive Laser Scanning

    Science.gov (United States)

    Khoo, Zhong Xun; Liu, Yong; Low, Zhi Hong; An, Jia; Chua, Chee Kai; Leong, Kah Fai

    2018-03-01

    Additive manufacturing has the potential to overcome the poor machinability of NiTi shape-memory alloy in fabricating smart structures of complex geometry. In recent years, a number of research activities on selective laser melting (SLM) of NiTi have been carried out to explore the optimal parameters for producing SLM NiTi with the desired phase transformation characteristics and shape-memory properties. Different effects of energy density and processing parameters on the properties of SLM NiTi were reported. In this research, a new approach—repetitive laser scanning—is introduced to meet these objectives as well. The results suggested that the laser absorptivity and heat conductivity of materials before and after the first scan significantly influence the final properties of SLM NiTi. With carefully controlled repetitive scanning process, the fabricated samples have demonstrated shape-memory effect of as high as 5.11% (with an average value of 4.61%) and exhibited comparable transformation characteristics as the NiTi powder used. These results suggest the potential for fabricating complex NiTi structures with similar properties to that of the conventionally produced NiTi parts.

  20. A Green Fabry-Perot Cavity for Jefferson Lab Hall A Compton Polarimetry

    International Nuclear Information System (INIS)

    Rakhman, Abdurahim; Souder, Paul; Nanda, Sirish

    2009-01-01

    A green laser (CW, 532 nm) based Fabry-Perot cavity for high precision Compton Polarimetry is under development in Hall A of the Jefferson Laboratory. In this paper, we present the principle and the preliminary studies for our test cavity.

  1. A Combination of Stop-and-Go and Electro-Tricycle Laser Scanning Systems for Rural Cadastral Surveys

    Directory of Open Access Journals (Sweden)

    Liang Zhong

    2016-09-01

    Full Text Available Over the past decade, land-based laser scanning technologies have been actively studied and implemented, in response to the need for detailed three-dimensional (3D data about our rural and urban environment for topographic mapping, cadastral mapping, and other street-level features, which are difficult and time consuming to measure by other instruments. For rural areas in China, the complex terrain and poor planning limit the applicability of this advanced technology. To improve the efficiency of rural surveys, we present two SSW (Shoushi and SiWei laser scanning systems for rapid topographic mapping: stop-and-go and electro-tricycle laser scanning systems. The objective of this paper is to evaluate whether laser scanning data collected by the developed SSW systems meet the accuracy requirements for rural homestead mapping. We investigated the performance of the two laser scanning systems on Ma’anshan Village, a small, typical village in Hubei Province, China. To obtain full coverage of the village, we fused the stop-and-go and electro-tricycle laser scanning data. The performance of the developed SSW systems is described by the results of building contours extracted from the fused data against the established building vector map.

  2. Semi-Automatic Registration of Airborne and Terrestrial Laser Scanning Data Using Building Corner Matching with Boundaries as Reliability Check

    Directory of Open Access Journals (Sweden)

    Liang Cheng

    2013-11-01

    Full Text Available Data registration is a prerequisite for the integration of multi-platform laser scanning in various applications. A new approach is proposed for the semi-automatic registration of airborne and terrestrial laser scanning data with buildings without eaves. Firstly, an automatic calculation procedure for thresholds in density of projected points (DoPP method is introduced to extract boundary segments from terrestrial laser scanning data. A new algorithm, using a self-extending procedure, is developed to recover the extracted boundary segments, which then intersect to form the corners of buildings. The building corners extracted from airborne and terrestrial laser scanning are reliably matched through an automatic iterative process in which boundaries from two datasets are compared for the reliability check. The experimental results illustrate that the proposed approach provides both high reliability and high geometric accuracy (average error of 0.44 m/0.15 m in horizontal/vertical direction for corresponding building corners for the final registration of airborne laser scanning (ALS and tripod mounted terrestrial laser scanning (TLS data.

  3. Intercomparison of Terrestrial Laser Scanning Instruments for Assessing Forested Ecosystems: A Brisbane Field Experiment

    Science.gov (United States)

    Armston, J.; Newnham, G.; Strahler, A. H.; Schaaf, C.; Danson, M.; Gaulton, R.; Zhang, Z.; Disney, M.; Sparrow, B.; Phinn, S. R.; Schaefer, M.; Burt, A.; Counter, S.; Erb, A.; Goodwin, N.; Hancock, S.; Howe, G.; Johansen, K.; Li, Z.; Lollback, G.; Martel, J.; Muir, J.; Paynter, I.; Saenz, E.; Scarth, P.; Tindall, D.; Walker, L.; Witte, C.; Woodgate, W.; Wu, S.

    2013-12-01

    During 28th July - 3rd August, 2013, an international group of researchers brought five terrestrial laser scanners (TLS) to long-term monitoring plots in three eucalyptus-dominated woodland sites near Brisbane, Queensland, Australia, to acquire scans at common locations for calibration and intercomparison.They included: DWEL - a dual-wavelength full-waveform laser scanner (Boston U., U. Massachusetts Lowell, U. Massachusetts Boston, USA) SALCA - a dual-wavelength full-waveform laser scanner (U. Salford, UK) CBL - a canopy biomass lidar, a small ultraportable low-cost multiple discrete return scanner (U. Massachusetts Boston, USA) Riegl VZ400 - a survey-grade commercial waveform scanner (Queensland Government and TERN, U. Queensland, Australia) FARO Focus 3D - a lightweight commercial phase-shift ranging laser scanner (U. Southern Queensland) Two plots were scanned at Karawatha Forest Park, a Terrestrial Ecosystem Research Network (TERN) Supersite, and one plot at D'Aguilar National Park. At each 50 x 100 m plot, a center scan point was surrounded by four scan points located 25 m away in a cross pattern allowing for 3-D reconstructions of scan sites in the form of point clouds. At several center points, multiple instrument configurations (i.e. different beam divergence, angular resolution, pulse rate) were acquired to test the impact of instrument specifications on separation of woody and non-woody materials and estimation of vegetation structure parameters. Three-dimensional Photopoint photographic panoramas were also acquired, providing reconstructions of stems in the form of point clouds using photogrammetric correlation methods. Calibrated reflectance targets were also scanned to compare instrument geometric and radiometric performance. Ancillary data included hemispherical photos, TRAC LAI/clumping measurements, spectra of leaves, bark, litter, and other target components. Wet and dry leaf weights determined water content. Planned intercomparison topics and

  4. I.R. and F.I.R. laser polarimetry as a diagnostic tool in high-β and Tokamak plasmas

    International Nuclear Information System (INIS)

    Pereira, D.; Machida, M.; Scalabrin, A.

    1986-01-01

    The change of the polarization state of an electromagnetic wave (E.M.W.) propagating across a magnetized plasma may be used to determine plasma parameters. In a plasma machine of the Tokamak type, the Faraday rotation of the E.M.W. allows for the determination of the product of the plasma electronic density by the poloidal magnetic field. A novel optical configuration which permits simultaneous measurements of these two parameters without the use of an auxiliary interferometric set up is proposed. By choosing appropriate laser wave length this method can be used in Tokamaks (lambda >= 1mm) and also in theta-Pinches plasmas (lambda approx. 10μm). The application of these results is discussed to plasma machines now in operation in Brazil, like the Tokamak/USP and theta-Pinch/UNICAMP, using lasers developed at UNICAMP. (Author) [pt

  5. Effect of laser power and scanning speed on laser deposited Ti6Al4V/TiB2 matrix composites

    CSIR Research Space (South Africa)

    Mokgalaka, MN

    2012-10-01

    Full Text Available Additive Manufacturing in Industry Conference, Kwa Maritane, Pilanesberg National Park, 31 October-2 November 2012 EFFECT OF LASER POWER AND SCANNING SPEED ON LASER DEPOSITED Ti6Al4V/TiB2 MATRIX COMPOSITES M.N. Mokgalaka2,1, S.L. Pityana1,2, A.P.I...

  6. Validation of phalanx bone three-dimensional surface segmentation from computed tomography images using laser scanning

    Energy Technology Data Exchange (ETDEWEB)

    DeVries, Nicole A.; Gassman, Esther E.; Kallemeyn, Nicole A. [The University of Iowa, Department of Biomedical Engineering, Center for Computer Aided Design, Iowa City, IA (United States); Shivanna, Kiran H. [The University of Iowa, Center for Computer Aided Design, Iowa City, IA (United States); Magnotta, Vincent A. [The University of Iowa, Department of Biomedical Engineering, Department of Radiology, Center for Computer Aided Design, Iowa City, IA (United States); Grosland, Nicole M. [The University of Iowa, Department of Biomedical Engineering, Department of Orthopaedics and Rehabilitation, Center for Computer Aided Design, Iowa City, IA (United States)

    2008-01-15

    To examine the validity of manually defined bony regions of interest from computed tomography (CT) scans. Segmentation measurements were performed on the coronal reformatted CT images of the three phalanx bones of the index finger from five cadaveric specimens. Two smoothing algorithms (image-based and Laplacian surface-based) were evaluated to determine their ability to represent accurately the anatomic surface. The resulting surfaces were compared with laser surface scans of the corresponding cadaveric specimen. The average relative overlap between two tracers was 0.91 for all bones. The overall mean difference between the manual unsmoothed surface and the laser surface scan was 0.20 mm. Both image-based and Laplacian surface-based smoothing were compared; the overall mean difference for image-based smoothing was 0.21 mm and 0.20 mm for Laplacian smoothing. This study showed that manual segmentation of high-contrast, coronal, reformatted, CT datasets can accurately represent the true surface geometry of bones. Additionally, smoothing techniques did not significantly alter the surface representations. This validation technique should be extended to other bones, image segmentation and spatial filtering techniques. (orig.)

  7. Validation of phalanx bone three-dimensional surface segmentation from computed tomography images using laser scanning

    International Nuclear Information System (INIS)

    DeVries, Nicole A.; Gassman, Esther E.; Kallemeyn, Nicole A.; Shivanna, Kiran H.; Magnotta, Vincent A.; Grosland, Nicole M.

    2008-01-01

    To examine the validity of manually defined bony regions of interest from computed tomography (CT) scans. Segmentation measurements were performed on the coronal reformatted CT images of the three phalanx bones of the index finger from five cadaveric specimens. Two smoothing algorithms (image-based and Laplacian surface-based) were evaluated to determine their ability to represent accurately the anatomic surface. The resulting surfaces were compared with laser surface scans of the corresponding cadaveric specimen. The average relative overlap between two tracers was 0.91 for all bones. The overall mean difference between the manual unsmoothed surface and the laser surface scan was 0.20 mm. Both image-based and Laplacian surface-based smoothing were compared; the overall mean difference for image-based smoothing was 0.21 mm and 0.20 mm for Laplacian smoothing. This study showed that manual segmentation of high-contrast, coronal, reformatted, CT datasets can accurately represent the true surface geometry of bones. Additionally, smoothing techniques did not significantly alter the surface representations. This validation technique should be extended to other bones, image segmentation and spatial filtering techniques. (orig.)

  8. Highly Accurate Tree Models Derived from Terrestrial Laser Scan Data: A Method Description

    Directory of Open Access Journals (Sweden)

    Jan Hackenberg

    2014-05-01

    Full Text Available This paper presents a method for fitting cylinders into a point cloud, derived from a terrestrial laser-scanned tree. Utilizing high scan quality data as the input, the resulting models describe the branching structure of the tree, capable of detecting branches with a diameter smaller than a centimeter. The cylinders are stored as a hierarchical tree-like data structure encapsulating parent-child neighbor relations and incorporating the tree’s direction of growth. This structure enables the efficient extraction of tree components, such as the stem or a single branch. The method was validated both by applying a comparison of the resulting cylinder models with ground truth data and by an analysis between the input point clouds and the models. Tree models were accomplished representing more than 99% of the input point cloud, with an average distance from the cylinder model to the point cloud within sub-millimeter accuracy. After validation, the method was applied to build two allometric models based on 24 tree point clouds as an example of the application. Computation terminated successfully within less than 30 min. For the model predicting the total above ground volume, the coefficient of determination was 0.965, showing the high potential of terrestrial laser-scanning for forest inventories.

  9. 3-D reconstruction of neurons from multichannel confocal laser scanning image series.

    Science.gov (United States)

    Wouterlood, Floris G

    2014-04-10

    A confocal laser scanning microscope (CLSM) collects information from a thin, focal plane and ignores out-of-focus information. Scanning of a specimen, with stepwise axial (Z-) movement of the stage in between each scan, produces Z-series of confocal images of a tissue volume, which then can be used to 3-D reconstruct structures of interest. The operator first configures separate channels (e.g., laser, filters, and detector settings) for each applied fluorochrome and then acquires Z-series of confocal images: one series per channel. Channel signal separation is extremely important. Measures to avoid bleaching are vital. Post-acquisition deconvolution of the image series is often performed to increase resolution before 3-D reconstruction takes place. In the 3-D reconstruction programs described in this unit, reconstructions can be inspected in real time from any viewing angle. By altering viewing angles and by switching channels off and on, the spatial relationships of 3-D-reconstructed structures with respect to structures visualized in other channels can be studied. Since each brand of CLSM, computer program, and 3-D reconstruction package has its own proprietary set of procedures, a general approach is provided in this protocol wherever possible. Copyright © 2014 John Wiley & Sons, Inc.

  10. Measurement of shape property distributions of quartzite aggregate from different crushers using 3D laser scanning system

    CSIR Research Space (South Africa)

    Mgangira, MB

    2016-01-01

    Full Text Available four crushers. In this paper, a description is provided on the quantification of particle shapes using data from a 3-D laser scanning device. The images from the laser were fully utilized in quantifying the shape descriptors in order to identify...

  11. Characterizing the geomorphic setting of precariously balanced rocks using terrestrial laser scanning technology

    Science.gov (United States)

    Haddad, D. E.; Arrowsmith, R.

    2009-12-01

    Terrestrial laser scanning (TLS) technology is rapidly becoming an effective three-dimensional imaging tool. Precariously balanced rocks are a subset of spheroidally weathered boulders. They are balanced on bedrock pedestals and are formed in upland drainage basins and pediments of exhumed plutons. Precarious rocks are used as negative evidence of earthquake-driven extreme ground motions. Field surveys of PBRs are coupled with cosmogenic radionuclide (CRN) surface exposure dating techniques to determine their exhumation rates. These rates are used in statistical simulations to estimate the magnitudes and recurrences of earthquake-generated extreme ground shaking as a means to physically validate seismic hazard analyses. However, the geomorphic setting of PBRs in the landscape is poorly constrained when interpreting their exhumation rates from CRN surface exposure dates. Are PBRs located on steep or gentle hillslopes? Are they located near drainages or hillslope crests? What geomorphic processes control the spatial distribution of PBRs in a landscape, and where do these processes dominate? Because the fundamental hillslope transport laws are largely controlled by local hillslope gradient and contributing area, the location of a PBR is controlled by the geomorphic agents and their rates acting on it. Our latest efforts involve using a combination of TLS and airborne laser swath mapping (ALSM) to characterize the geomorphic situation of PBRs. We used a Riegl LPM 800i (LPM 321) terrestrial laser scanner to scan a ~1.5 m tall by ~1 m wide precariously balanced rock in the Granite Dells, central Arizona. The PBR was scanned from six positions, and the scans were aligned to a point cloud totaling 3.4M points. We also scanned a ~50 m by ~150 m area covering PBR hillslopes from five scan positions. The resulting 5.5M points were used to create a digital terrain model of precarious rocks and their hillslopes. Our TLS- and ALSM-generated surface models and DEMs provide a

  12. Image-based tracking system for vibration measurement of a rotating object using a laser scanning vibrometer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongkyu, E-mail: akein@gist.ac.kr; Khalil, Hossam; Jo, Youngjoon; Park, Kyihwan, E-mail: khpark@gist.ac.kr [School of Mechatronics, Gwangju Institute of Science and Technology, Buk-gu, Gwangju, South Korea, 500-712 (Korea, Republic of)

    2016-06-28

    An image-based tracking system using laser scanning vibrometer is developed for vibration measurement of a rotating object. The proposed system unlike a conventional one can be used where the position or velocity sensor such as an encoder cannot be attached to an object. An image processing algorithm is introduced to detect a landmark and laser beam based on their colors. Then, through using feedback control system, the laser beam can track a rotating object.

  13. Efficacy of patterned scan laser in treatment of macular edema and retinal neovascularization

    Directory of Open Access Journals (Sweden)

    Dimple Modi

    2009-08-01

    -term follow-up. PASCAL® photocoagulation can be performed quicker with less discomfort for patients.Keywords: diabetic retinopathy, laser, macular edema, PASCAL, patterned scan laser, photocoagulation, retinal neovascularization

  14. The rf sigmameter: A digital phase-locked technique for accurate long-range laser scanning

    International Nuclear Information System (INIS)

    Zhu, M.; Hall, J.L.

    1986-01-01

    The authors use a new version of a sigmameter, the two-channel field-widened rf sigmameter, to map optical frequency into the phase of an rf signal. This enables them to lock the laser frequency on the interferometer by using a phase-locked loop (PLL). Controlling the reference phase of the PLL electronically, they are able to scan the laser frequency over a long range step by step or with substeps. The systematic error of each substep is cancelled automatically when the authors change one step (which is ten substeps, for example), and that of each step is cancelled when they change the reference phase by 2π (which corresponds to 256 steps in their scheme)

  15. Investigation of the petrophysical properties of a porous sandstone sample using confocal scanning laser microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Petford, N. [Kingston Univ., Centre for Earth and Environmental Science Research, Kingston (United Kingdom); Davidson, G. [University Coll., Dept. of Electronic and Electrical Engineering, London (United Kingdom); Miller, J.A. [Cambridge Univ., Dept. of Earth Sciences, Cambridge (United Kingdom)

    2001-05-01

    Confocal scanning laser microscopy (CSLM) is used to produce images of the two- and three-dimensional distribution and geometry of pore space in a reservoir sandstone and measure the 2D distribution of pore throat radii. Non-destructive serial sectioning of the rock using laser light at 100% illumination, combined with image thresholding and histogram equalization techniques allow the pore volume structure of the uppermost 100 {mu}m of the sample to be reconstructed. Negative imaging of the pore volume gave superior depth and feature resolution compared to positive (reflection) imaging. Artefacts encountered in applying classical Medial Axial Transforms to CSLM images include branch networks dominated by coordination numbers of 3. Skeletonization using Euclidean distance maps gives increased accuracy in the description of the pore network. Measured pore throat size distribution in the rock is strongly exponential and described by the expression y 219e{sup -0.25x} where y is the number of pore throats. (Author)

  16. SENSOR-TOPOLOGY BASED SIMPLICIAL COMPLEX RECONSTRUCTION FROM MOBILE LASER SCANNING

    Directory of Open Access Journals (Sweden)

    S. Guinard

    2018-05-01

    Full Text Available We propose a new method for the reconstruction of simplicial complexes (combining points, edges and triangles from 3D point clouds from Mobile Laser Scanning (MLS. Our main goal is to produce a reconstruction of a scene that is adapted to the local geometry of objects. Our method uses the inherent topology of the MLS sensor to define a spatial adjacency relationship between points. We then investigate each possible connexion between adjacent points and filter them by searching collinear structures in the scene, or structures perpendicular to the laser beams. Next, we create triangles for each triplet of self-connected edges. Last, we improve this method with a regularization based on the co-planarity of triangles and collinearity of remaining edges. We compare our results to a naive simplicial complexes reconstruction based on edge length.

  17. Sensor-Topology Based Simplicial Complex Reconstruction from Mobile Laser Scanning

    Science.gov (United States)

    Guinard, S.; Vallet, B.

    2018-05-01

    We propose a new method for the reconstruction of simplicial complexes (combining points, edges and triangles) from 3D point clouds from Mobile Laser Scanning (MLS). Our main goal is to produce a reconstruction of a scene that is adapted to the local geometry of objects. Our method uses the inherent topology of the MLS sensor to define a spatial adjacency relationship between points. We then investigate each possible connexion between adjacent points and filter them by searching collinear structures in the scene, or structures perpendicular to the laser beams. Next, we create triangles for each triplet of self-connected edges. Last, we improve this method with a regularization based on the co-planarity of triangles and collinearity of remaining edges. We compare our results to a naive simplicial complexes reconstruction based on edge length.

  18. Low temperature laser scanning microscopy of a superconducting radio-frequency cavity

    Science.gov (United States)

    Ciovati, G.; Anlage, Steven M.; Baldwin, C.; Cheng, G.; Flood, R.; Jordan, K.; Kneisel, P.; Morrone, M.; Nemes, G.; Turlington, L.; Wang, H.; Wilson, K.; Zhang, S.

    2012-03-01

    An apparatus was developed to obtain, for the first time, 2D maps of the surface resistance of the inner surface of an operating superconducting radio-frequency niobium cavity by a low-temperature laser scanning microscopy technique. This allows identifying non-uniformities of the surface resistance with a spatial resolution of about 2.4 mm and surface resistance resolution of ˜1 μΩ at 3.3 GHz. A signal-to-noise ratio of about 10 dB was obtained with 240 mW laser power and 1 Hz modulation frequency. The various components of the apparatus, the experimental procedure and results are discussed in detail in this contribution.

  19. Low temperature laser scanning microscopy of a superconducting radio-frequency cavity.

    Science.gov (United States)

    Ciovati, G; Anlage, Steven M; Baldwin, C; Cheng, G; Flood, R; Jordan, K; Kneisel, P; Morrone, M; Nemes, G; Turlington, L; Wang, H; Wilson, K; Zhang, S

    2012-03-01

    An apparatus was developed to obtain, for the first time, 2D maps of the surface resistance of the inner surface of an operating superconducting radio-frequency niobium cavity by a low-temperature laser scanning microscopy technique. This allows identifying non-uniformities of the surface resistance with a spatial resolution of about 2.4 mm and surface resistance resolution of ~1 μΩ at 3.3 GHz. A signal-to-noise ratio of about 10 dB was obtained with 240 mW laser power and 1 Hz modulation frequency. The various components of the apparatus, the experimental procedure and results are discussed in detail in this contribution.

  20. THE USE OF COMPUTER VISION ALGORITHMS FOR AUTOMATIC ORIENTATION OF TERRESTRIAL LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    J. S. Markiewicz

    2016-06-01

    Full Text Available The paper presents analysis of the orientation of terrestrial laser scanning (TLS data. In the proposed data processing methodology, point clouds are considered as panoramic images enriched by the depth map. Computer vision (CV algorithms are used for orientation, which are applied for testing the correctness of the detection of tie points and time of computations, and for assessing difficulties in their implementation. The BRISK, FASRT, MSER, SIFT, SURF, ASIFT and CenSurE algorithms are used to search for key-points. The source data are point clouds acquired using a Z+F 5006h terrestrial laser scanner on the ruins of Iłża Castle, Poland. Algorithms allowing combination of the photogrammetric and CV approaches are also presented.

  1. The Use of Computer Vision Algorithms for Automatic Orientation of Terrestrial Laser Scanning Data

    Science.gov (United States)

    Markiewicz, Jakub Stefan

    2016-06-01

    The paper presents analysis of the orientation of terrestrial laser scanning (TLS) data. In the proposed data processing methodology, point clouds are considered as panoramic images enriched by the depth map. Computer vision (CV) algorithms are used for orientation, which are applied for testing the correctness of the detection of tie points and time of computations, and for assessing difficulties in their implementation. The BRISK, FASRT, MSER, SIFT, SURF, ASIFT and CenSurE algorithms are used to search for key-points. The source data are point clouds acquired using a Z+F 5006h terrestrial laser scanner on the ruins of Iłża Castle, Poland. Algorithms allowing combination of the photogrammetric and CV approaches are also presented.

  2. Scanning laser techniques for dynamic thermo-magnetic recording onto stationary media

    Energy Technology Data Exchange (ETDEWEB)

    Clegg, Warwick; Jenkins, David; Helian, Na; Windmill, James; Windmill, Robert; Atkinson, Ron; Hendren, Bill; Wright, C. David

    2002-09-01

    Scanning laser microscopes (SLMs) have been used to characterise the magnetic properties of materials for some time (J. Magn. Magn. Mater. 95(1) (1991); IEEE Trans. Magn. 31(6 Pt. 1) (1995)). An SLM has been designed to facilitate a number of operating modes: both for writing and reading magneto-optical data. The current SLM is capable of thermo-magnetically recording bits onto magneto-optical thin films. Unlike previous SLMs, the current instrument has been designed to write bits both statically and dynamically onto stationary media. It will be used to write to magneto-optic (MO) disk material thermo-magnetically prior to imaging. Images may be derived from the longitudinal and polar magneto-optic Kerr effects, which are wavelength dependent, using the appropriate laser wavelength. In this paper the two configurations for dynamic recording are described.

  3. Scanning laser techniques for dynamic thermo-magnetic recording onto stationary media

    International Nuclear Information System (INIS)

    Clegg, Warwick; Jenkins, David; Helian, Na; Windmill, James; Windmill, Robert; Atkinson, Ron; Hendren, Bill; Wright, C. David

    2002-01-01

    Scanning laser microscopes (SLMs) have been used to characterise the magnetic properties of materials for some time (J. Magn. Magn. Mater. 95(1) (1991); IEEE Trans. Magn. 31(6 Pt. 1) (1995)). An SLM has been designed to facilitate a number of operating modes: both for writing and reading magneto-optical data. The current SLM is capable of thermo-magnetically recording bits onto magneto-optical thin films. Unlike previous SLMs, the current instrument has been designed to write bits both statically and dynamically onto stationary media. It will be used to write to magneto-optic (MO) disk material thermo-magnetically prior to imaging. Images may be derived from the longitudinal and polar magneto-optic Kerr effects, which are wavelength dependent, using the appropriate laser wavelength. In this paper the two configurations for dynamic recording are described

  4. Application of laser scanning technique in earthquake protection of Istanbul's historical heritage buildings

    Science.gov (United States)

    Çaktı, Eser; Ercan, Tülay; Dar, Emrullah

    2017-04-01

    Istanbul's vast historical and cultural heritage is under constant threat of earthquakes. Historical records report repeated damages to the city's landmark buildings. Our efforts towards earthquake protection of several buildings in Istanbul involve earthquake monitoring via structural health monitoring systems, linear and non-linear structural modelling and analysis in search of past and future earthquake performance, shake-table testing of scaled models and non-destructive testing. More recently we have been using laser technology in monitoring structural deformations and damage in five monumental buildings which are Hagia Sophia Museum and Fatih, Sultanahmet, Süleymaniye and Mihrimah Sultan Mosques. This presentation is about these efforts with special emphasis on the use of laser scanning in monitoring of edifices.

  5. THE BENEFITS OF TERRESTRIAL LASER SCANNING AND HYPERSPECTRAL DATA FUSION PRODUCTS

    Directory of Open Access Journals (Sweden)

    S. J. Buckley

    2012-10-01

    Full Text Available Close range hyperspectral imaging is a developing method for the analysis and identification of material composition in many applications, such as in within the earth sciences. Using compact imaging devices in the field allows near-vertical topography to be imaged, thus bypassing the key limitations of viewing angle and resolution that preclude the use of airborne and spaceborne platforms. Terrestrial laser scanning allows 3D topography to be captured with high precision and spatial resolution. The combination of 3D geometry from laser scanning, and material properties from hyperspectral imaging allows new fusion products to be created, adding new information for solving application problems. This paper highlights the advantages of terrestrial lidar and hyperspectral integration, focussing on the qualitative and quantitative aspects, with examples from a geological field application. Accurate co-registration of the two data types is required. This allows 2D pixels to be linked to the 3D lidar geometry, giving increased quantitative analysis as classified material vectors are projected to 3D space for calculation of areas and examination of spatial relationships. User interpretation of hyperspectral results in a spatially-meaningful manner is facilitated using visual methods that combine the geometric and mineralogical products in a 3D environment. Point cloud classification and the use of photorealistic modelling enhance qualitative validation and interpretation, and allow image registration accuracy to be checked. A method for texture mapping of lidar meshes with multiple image textures, both conventional digital photos and hyperspectral results, is described. The integration of terrestrial laser scanning and hyperspectral imaging is a valuable means of providing new analysis methods, suitable for many applications requiring linked geometric and chemical information.

  6. a New Approach for Subway Tunnel Deformation Monitoring: High-Resolution Terrestrial Laser Scanning

    Science.gov (United States)

    Li, J.; Wan, Y.; Gao, X.

    2012-07-01

    With the improvement of the accuracy and efficiency of laser scanning technology, high-resolution terrestrial laser scanning (TLS) technology can obtain high precise points-cloud and density distribution and can be applied to high-precision deformation monitoring of subway tunnels and high-speed railway bridges and other fields. In this paper, a new approach using a points-cloud segmentation method based on vectors of neighbor points and surface fitting method based on moving least squares was proposed and applied to subway tunnel deformation monitoring in Tianjin combined with a new high-resolution terrestrial laser scanner (Riegl VZ-400). There were three main procedures. Firstly, a points-cloud consisted of several scanning was registered by linearized iterative least squares approach to improve the accuracy of registration, and several control points were acquired by total stations (TS) and then adjusted. Secondly, the registered points-cloud was resampled and segmented based on vectors of neighbor points to select suitable points. Thirdly, the selected points were used to fit the subway tunnel surface with moving least squares algorithm. Then a series of parallel sections obtained from temporal series of fitting tunnel surfaces were compared to analysis the deformation. Finally, the results of the approach in z direction were compared with the fiber optical displacement sensor approach and the results in x, y directions were compared with TS respectively, and comparison results showed the accuracy errors of x, y, z directions were respectively about 1.5 mm, 2 mm, 1 mm. Therefore the new approach using high-resolution TLS can meet the demand of subway tunnel deformation monitoring.

  7. A NEW APPROACH FOR SUBWAY TUNNEL DEFORMATION MONITORING: HIGH-RESOLUTION TERRESTRIAL LASER SCANNING

    Directory of Open Access Journals (Sweden)

    J. Li

    2012-07-01

    Full Text Available With the improvement of the accuracy and efficiency of laser scanning technology, high-resolution terrestrial laser scanning (TLS technology can obtain high precise points-cloud and density distribution and can be applied to high-precision deformation monitoring of subway tunnels and high-speed railway bridges and other fields. In this paper, a new approach using a points-cloud segmentation method based on vectors of neighbor points and surface fitting method based on moving least squares was proposed and applied to subway tunnel deformation monitoring in Tianjin combined with a new high-resolution terrestrial laser scanner (Riegl VZ-400. There were three main procedures. Firstly, a points-cloud consisted of several scanning was registered by linearized iterative least squares approach to improve the accuracy of registration, and several control points were acquired by total stations (TS and then adjusted. Secondly, the registered points-cloud was resampled and segmented based on vectors of neighbor points to select suitable points. Thirdly, the selected points were used to fit the subway tunnel surface with moving least squares algorithm. Then a series of parallel sections obtained from temporal series of fitting tunnel surfaces were compared to analysis the deformation. Finally, the results of the approach in z direction were compared with the fiber optical displacement sensor approach and the results in x, y directions were compared with TS respectively, and comparison results showed the accuracy errors of x, y, z directions were respectively about 1.5 mm, 2 mm, 1 mm. Therefore the new approach using high-resolution TLS can meet the demand of subway tunnel deformation monitoring.

  8. Volumetric evolution of Surtsey, Iceland, from topographic maps and scanning airborne laser altimetry

    Science.gov (United States)

    Garvin, J.B.; Williams, R.S.; Frawley, J.J.; Krabill, W.B.

    2000-01-01

    The volumetric evolution of Surtsey has been estimated on the basis of digital elevation models derived from NASA scanning airborne laser altimeter surveys (20 July 1998), as well as digitized 1:5,000-scale topographic maps produced by the National Land Survey of Iceland and by Norrman. Subaerial volumes have been computed from co-registered digital elevation models (DEM's) from 6 July 1968, 11 July 1975, 16 July 1993, and 20 July 1998 (scanning airborne laser altimetry), as well as true surface area (above mean sea level). Our analysis suggests that the subaerial volume of Surtsey has been reduced from nearly 0.100 km3 on 6 July 1968 to 0.075 km3 on 20 July 1998. Linear regression analysis of the temporal evolution of Surtsey's subaerial volume indicates that most of its subaerial surface will be at or below mean sea-level by approximately 2100. This assumes a conservative estimate of continuation of the current pace of marine erosion and mass-wasting on the island, including the indurated core of the conduits of the Surtur I and Surtur II eruptive vents. If the conduits are relatively resistant to marine erosion they will become sea stacks after the rest of the island has become a submarine shoal, and some portions of the island could survive for centuries. The 20 July 1998 scanning laser altimeter surveys further indicate rapid enlargement of erosional canyons in the northeastern portion of the partial tephra ring associated with Surtur I. Continued airborne and eventually spaceborne topographic surveys of Surtsey are planned to refine the inter-annual change of its subaerial volume.

  9. Confocal laser scanning microscopy to estimate nanoparticles’ human skin penetration in vitro

    Directory of Open Access Journals (Sweden)

    Zou Y

    2017-10-01

    Full Text Available Ying Zou,1,2,* Anna Celli,2,3,* Hanjiang Zhu,2,* Akram Elmahdy,2 Yachao Cao,2 Xiaoying Hui,2 Howard Maibach2 1Skin & Cosmetic Research Department, Shanghai Skin Disease Hospital, Shanghai, People’s Republic of China; 2Department of Dermatology, School of Medicine, University of California San Francisco, San Francisco, CA, USA; 3San Francisco Veterans Medical Center, San Francisco, CA, USA *These authors contributed equally to this work Objective: With rapid development of nanotechnology, there is increasing interest in nanoparticle (NP application and its safety and efficacy on human skin. In this study, we utilized confocal laser scanning microscopy to estimate NP skin penetration.Methods: Three different-sized polystyrene NPs marked with red fluorescence were applied to human skin, and Calcium Green 5N was used as a counterstain. Dimethyl sulfoxide (DMSO and ethanol were used as alternative vehicles for NPs. Tape stripping was utilized as a barrier-damaged skin model. Skin biopsies dosed with NPs were incubated at 4°C or 37°C for 24 hours and imaged using confocal laser scanning microscopy.Results: NPs were localized in the stratum corneum (SC and hair follicles without penetrating the epidermis/dermis. Barrier alteration with tape stripping and change in incubation temperature did not induce deeper penetration. DMSO enhanced NP SC penetration but ethanol did not.Conclusion: Except with DMSO vehicle, these hydrolyzed polystyrene NPs did not penetrate intact or barrier-damaged human “viable” epidermis. For further clinical relevance, in vivo human skin studies and more sensitive analytic chemical methodology are suggested. Keywords: nanoparticles, skin penetration, stratum corneum, confocal laser scanning microscopy, tape stripping

  10. ANALYSIS OF MOBILE LASER SCANNING DATA AND MULTI-VIEW IMAGE RECONSTRUCTION

    Directory of Open Access Journals (Sweden)

    C. Briese

    2012-07-01

    Full Text Available The combination of laser scanning (LS, active, direct 3D measurement of the object surface and photogrammetry (high geometric and radiometric resolution is widely applied for object reconstruction (e.g. architecture, topography, monitoring, archaeology. Usually the results are a coloured point cloud or a textured mesh. The geometry is typically generated from the laser scanning point cloud and the radiometric information is the result of image acquisition. In the last years, next to significant developments in static (terrestrial LS and kinematic LS (airborne and mobile LS hardware and software, research in computer vision and photogrammetry lead to advanced automated procedures in image orientation and image matching. These methods allow a highly automated generation of 3D geometry just based on image data. Founded on advanced feature detector techniques (like SIFT (Scale Invariant Feature Transform very robust techniques for image orientation were established (cf. Bundler. In a subsequent step, dense multi-view stereo reconstruction algorithms allow the generation of very dense 3D point clouds that represent the scene geometry (cf. Patch-based Multi-View Stereo (PMVS2. Within this paper the usage of mobile laser scanning (MLS and simultaneously acquired image data for an advanced integrated scene reconstruction is studied. For the analysis the geometry of a scene is generated by both techniques independently. Then, the paper focuses on the quality assessment of both techniques. This includes a quality analysis of the individual surface models and a comparison of the direct georeferencing of the images using positional and orientation data of the on board GNSS-INS system and the indirect georeferencing of the imagery by automatic image orientation. For the practical evaluation a dataset from an archaeological monument is utilised. Based on the gained knowledge a discussion of the results is provided and a future strategy for the integration of

  11. Street-side vehicle detection, classification and change detection using mobile laser scanning data

    Science.gov (United States)

    Xiao, Wen; Vallet, Bruno; Schindler, Konrad; Paparoditis, Nicolas

    2016-04-01

    Statistics on street-side car parks, e.g. occupancy rates, parked vehicle types, parking durations, are of great importance for urban planning and policy making. Related studies, e.g. vehicle detection and classification, mostly focus on static images or video. Whereas mobile laser scanning (MLS) systems are increasingly utilized for urban street environment perception due to their direct 3D information acquisition, high accuracy and movability. In this paper, we design a complete system for car park monitoring, including vehicle recognition, localization, classification and change detection, from laser scanning point clouds. The experimental data are acquired by an MLS system using high frequency laser scanner which scans the streets vertically along the system's moving trajectory. The point clouds are firstly classified as ground, building façade, and street objects which are then segmented using state-of-the-art methods. Each segment is treated as an object hypothesis, and its geometric features are extracted. Moreover, a deformable vehicle model is fitted to each object. By fitting an explicit model to the vehicle points, detailed information, such as precise position and orientation, can be obtained. The model parameters are also treated as vehicle features. Together with the geometric features, they are applied to a supervised learning procedure for vehicle or non-vehicle recognition. The classes of detected vehicles are also investigated. Whether vehicles have changed across two datasets acquired at different times is detected to estimate the durations. Here, vehicles are trained pair-wisely. Two same or different vehicles are paired up as training samples. As a result, the vehicle recognition, classification and change detection accuracies are 95.9%, 86.0% and 98.7%, respectively. Vehicle modelling improves not only the recognition rate, but also the localization precision compared to bounding boxes.

  12. Weld quality inspection using laser-EMAT ultrasonic system and C-scan method

    Science.gov (United States)

    Yang, Lei; Ume, I. Charles

    2014-02-01

    Laser/EMAT ultrasonic technique has attracted more and more interests in weld quality inspection because of its non-destructive and non-contact characteristics. When ultrasonic techniques are used to detect welds joining relative thin plates, the dominant ultrasonic waves present in the plates are Lamb waves, which propagate all through the thickness. Traditional Time of Flight(ToF) method loses its power. The broadband nature of laser excited ultrasound plus dispersive and multi-modal characteristic of Lamb waves make the EMAT acquired signals very complicated in this situation. Challenge rises in interpreting the received signals and establishing relationship between signal feature and weld quality. In this paper, the laser/EMAT ultrasonic technique was applied in a C-scan manner to record full wave propagation field over an area close to the weld. Then the effect of weld defect on the propagation field of Lamb waves was studied visually by watching an movie resulted from the recorded signals. This method was proved to be effective to detect the presence of hidden defect in the weld. Discrete wavelet transform(DWT) was applied to characterize the acquired ultrasonic signals and ideal band-pass filter was used to isolate wave components most sensitive to the weld defect. Different interactions with the weld defect were observed for different wave components. Thus this C-Scan method, combined with DWT and ideal band-pass filter, proved to be an effective methodology to experimentally study interactions of various laser excited Lamb Wave components with weld defect. In this work, the method was demonstrated by inspecting a hidden local incomplete penetration in weld. In fact, this method can be applied to study Lamb Wave interactions with any type of structural inconsistency. This work also proposed a ideal filtered based method to effectively reduce the total experimental time.

  13. Motion Detection from Mobile Robots with Fuzzy Threshold Selection in Consecutive 2D Laser Scans

    Directory of Open Access Journals (Sweden)

    María A. Martínez

    2015-01-01

    Full Text Available Motion detection and tracking is a relevant problem for mobile robots during navigation to avoid collisions in dynamic environments or in applications where service robots interact with humans. This paper presents a simple method to distinguish mobile obstacles from the environment that is based on applying fuzzy threshold selection to consecutive two-dimensional (2D laser scans previously matched with robot odometry. The proposed method has been tested with the Auriga-α mobile robot in indoors to estimate the motion of nearby pedestrians.

  14. Distinguishing Buried Objects in Extremely Shallow Underground by Frequency Response Using Scanning Laser Doppler Vibrometer

    Science.gov (United States)

    Touma Abe,; Tsuneyoshi Sugimoto,

    2010-07-01

    A sound wave vibration using a scanning laser Doppler vibrometer are used as a method of exploring and imaging an extremely shallow underground. Flat speakers are used as a vibration source. We propose a method of distinguishing a buried object using a response range of a frequencies corresponding to a vibration velocities. Buried objects (plastic containers, a hollow steel can, an unglazed pot, and a stone) are distinguished using a response range of frequencies. Standardization and brightness imaging are used as methods of discrimination. As a result, it was found that the buried objects show different response ranges of frequencies. From the experimental results, we confirmed the effectiveness of our proposed method.

  15. High-resolution adaptive optics scanning laser ophthalmoscope with multiple deformable mirrors

    Science.gov (United States)

    Chen, Diana C.; Olivier, Scot S.; Jones; Steven M.

    2010-02-23

    An adaptive optics scanning laser ophthalmoscopes is introduced to produce non-invasive views of the human retina. The use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the MEMS mirror alone, and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. The large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

  16. Low temperature laser scanning microscopy of a superconducting radio-frequency cavity

    OpenAIRE

    Ciovati, G.; Anlage, Steven M.; Baldwin, C.; Cheng, G.; Flood, R.; Jordan, K.; Kneisel, P.; Morrone, M.; Nemes, G.; Turlington, L.; Wang, H.; Wilson, K.; Zhang, S.

    2012-01-01

    An apparatus was developed to obtain, for the first time, 2D maps of the surface resistance of the inner surface of an operating superconducting radio-frequency niobium cavity by a low-temperature laser scanning microscopy technique. This allows identifying non-uniformities of the surface resistance with a spatial resolution of about one order of magnitude better than with earlier methods and surface resistance resolution of ~ 1 micro-Ohm at 3.3 GHz. A signal-to-noise ratio of about 10 dB was...

  17. Observation of microorganism colonies using a scanning-laser-beam pH-sensing microscope

    International Nuclear Information System (INIS)

    Nakao, M.; Inoue, S.; Oishi, R.; Yoshinobu, T.; Iwasaki, H.

    1995-01-01

    The extracellular pH-distribution of colonies of Saccharomyces cerevisiae (yeast) and Escherichia coli (E. coli) were observed using a newly-developed scanning-laser-beam pH-sensing microscope. Colonies were incubated either on top of agarose plates or between the pH-sensing surface and the agar. In the latter case, colony growth was observed in-situ. The colonies could be observed within a period as short as 8 h for E. coli. The pH-distribution profiles by the colonies were found to be very sharp, in agreement with simulation results. (author)

  18. A novel cryogenic scanning laser microscope tested on Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Holm, Jesper; Mygind, Jesper

    1995-01-01

    to a very localized heating induced by irradiation with 675 nm wavelength light from a semiconductor laser. The hot spot is moved by a specially designed piezoelectric scanner sweeping the tip of a single-mode optical fiber a few µm above the circuit. Depending on the scanner design the scanning area can...... be as large as 50×500 µm2 at 4.2 K. The microscope can be operated in the temperature range 2–300 K using a standard temperature controller. The central microscope body is mounted inside the vacuum can of a dip-stick-type cryoprobe. A damped spring system is used to reduce interference from extraneous...

  19. Confocal laser scanning microscopy in vivo for diagnosing melanocytic skin neoplasms

    Directory of Open Access Journals (Sweden)

    A. A. Kubanova

    2014-01-01

    Full Text Available The authors discuss the use of confocal laser scanning microscopy in vivo (CLSM for diagnosing melanocytic skin neoplasms and its value for early diagnostics of melanoma. CLSM is an innovation noninvasive visual examination method for real-time multiple and painless examinations of the patient’s skin without injuring the skin integument. The method ensures early diagnostics of skin melanomas with high sensitivity and specificity, which makes it possible to use CLSM for screening melanocytic skin neoplasms for the sake of the early onset of treatment to save patient life and health.

  20. Ti-6Al-4V electron beam weld qualification using laser scanning confocal microscopy

    International Nuclear Information System (INIS)

    Wanjara, P.; Brochu, M.; Jahazi, M.

    2005-01-01

    Processing conditions for manufacturing Ti-6Al-4V components by welding using an electron beam source are known to influence the transformation microstructure in the narrow fusion and heat-affected zones of the weld region. This work examined the effect of multiple-sequence welding on the characteristics of the transformed beta microstructure, using laser scanning confocal microscopy to resolve the Widmanstaetten alpha-beta structure in the fusion zone. The evolution in the alpha interlamellar spacing and plate thickness with processing was then related to microhardness measurements in the weld region

  1. Integrating Airborne and Terrestrial Laser Scanning data to monitor active landsliding

    Science.gov (United States)

    Székely, B.; Molnár, G.; Roncat, A.; Lehner, H.; Gaisecker, Th.; Drexel, P.

    2009-04-01

    Active slope processes often endanger various built-up objects and, as a consequence, sometimes human lives as well. Data acquision on the status and evolution of such slopes, especially those that had already affected by landsliding, therefore is a primary target for engineering geomorphic research. The method of laser scanning provides an appropriate data collection technique with the requested accuracy. Data from repeated Airborne Laser Scanning (ALS) campaigns are suitable to be analysed for the slow, incipient movements of the slope. The problem of this surveying technique is that repetition time is strongly dependent on the financial resources of the monitoring project, and often the requested recurrence of flight campaigns cannot be achieved. A possible solution to densify the data acquisition in time is the application of Terrestrial Laser Scanning (TLS) and intergration of its data with ALS data sets. TLS has the advantage of flexibility and shorter observation distances compared to ALS. This technique needs special considerations and tedious processing since the geometric setting of the data acquision considerably differ in TLS and ALS. Furthermore, obstacles in the landscape may partly hamper the data acqusition which rarely the case in ALS. Our case study area is a several-decade-long active landsliding in Doren (Federal State Vorarlberg, Austria) that as it develops, it is about to endangers houses of the locality. The site is especially suitable for the project, because multi-temporal data sets (from ALS flight campaigns in 2003, 2006 and 2007, respectively) of this area are available. The data integration is carried out in the form of production of point clouds (sensed from various points of the valley sides) and we compared the results with the results of the previous ALS campaigns. With the planned repetition of the TLS measurements new and detailed insights can be achieved concerning the evolution of the incipient and on-going slow motions. This

  2. Investigation of strain heterogeneities by laser scanning extensometry in strain ageing materials: application to zirconium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Graff, S.; Forest, S.; Strudel, J.L. [Centre des Materiaux / UMR 7633, Ecole des Mines de Paris / CNRS, BP 87, 91003 Evry (France); Dierke, H.; Neuhauser, H. [Institut fur Physik der Kondensierten Materie, 38106 Braunschweig (Germany); Prioul, C. [MSSMAT, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Chatenay-Malabry (France); Bechade, J.L. [SRMA, CEA Saclay, 91191 Gif sur Yvette (France)

    2005-07-01

    Laser scanning extensometry was used to detect and characterize propagating plastic instabilities such as the Luders bands at the millimeter scale. Spatio-temporal plastic heterogeneities are due to either static or dynamic strain ageing (SSA and DSA) phenomena. Regarding zirconium alloys, different type of heterogeneities were observed: their features strongly depended on mechanical test conditions. In one case, they appeared to be non propagating but preserved along the stress-strain curve and were associated with SSA effects such as stress peaks after relaxation periods or after unloading steps with waiting times. In other case, they appeared as non propagating but were not associated with SSA effects. (authors)

  3. Investigation of strain heterogeneities by laser scanning extensometry in strain ageing materials: application to zirconium alloys

    International Nuclear Information System (INIS)

    Graff, S.; Forest, S.; Strudel, J.L.; Dierke, H.; Neuhauser, H.; Prioul, C.; Bechade, J.L.

    2005-01-01

    Laser scanning extensometry was used to detect and characterize propagating plastic instabilities such as the Luders bands at the millimeter scale. Spatio-temporal plastic heterogeneities are due to either static or dynamic strain ageing (SSA and DSA) phenomena. Regarding zirconium alloys, different type of heterogeneities were observed: their features strongly depended on mechanical test conditions. In one case, they appeared to be non propagating but preserved along the stress-strain curve and were associated with SSA effects such as stress peaks after relaxation periods or after unloading steps with waiting times. In other case, they appeared as non propagating but were not associated with SSA effects. (authors)

  4. Scanning cross-correlator for monitoring uniform 3D ellipsoidal laser beams

    CERN Document Server

    Zelenogorskii, V V; Gacheva, E I; Gelikonov, G V; Krasilnikov, M; Mart'yanov, M A; Mironov, S Yu; Potemkin, A K; Syresin, E M; Stephan, F; Khazanov, E A

    2014-01-01

    The specific features of experimental implementation of a cross-correlator with a scan rate above 1600 cm s(-1) and a spatial delay amplitude of more than 15 mm are considered. The possibility of measuring the width of femtosecond pulses propagating in a train 300 mu s in duration with a repetition rate of 1 MHz is demonstrated. A time resolution of 300 fs for the maximum time window of 50 ps is attained.The cross-correlator is aimed at testing 3D pulses of a laser driver of an electron photo-injector.

  5. Documenting Bronze Age Akrotiri on Thera Using Laser Scanning, Image-Based Modelling and Geophysical Prospection

    Science.gov (United States)

    Trinks, I.; Wallner, M.; Kucera, M.; Verhoeven, G.; Torrejón Valdelomar, J.; Löcker, K.; Nau, E.; Sevara, C.; Aldrian, L.; Neubauer, E.; Klein, M.

    2017-02-01

    The excavated architecture of the exceptional prehistoric site of Akrotiri on the Greek island of Thera/Santorini is endangered by gradual decay, damage due to accidents, and seismic shocks, being located on an active volcano in an earthquake-prone area. Therefore, in 2013 and 2014 a digital documentation project has been conducted with support of the National Geographic Society in order to generate a detailed digital model of Akrotiri's architecture using terrestrial laser scanning and image-based modeling. Additionally, non-invasive geophysical prospection has been tested in order to investigate its potential to explore and map yet buried archaeological remains. This article describes the project and the generated results.

  6. Research on Mechanical Properties of Concrete Constructs Based on Terrestrial Laser Scanning Measurement

    Directory of Open Access Journals (Sweden)

    Hao Yang

    2016-05-01

    Full Text Available Terrestrial laser scanning (TLS technology is broadly accepted as a structural health monitoring device for reinforced concrete (RC composite structures. Both experiments and numerical analysis are considered. In this submit, measurements were conducted for the composite concrete beams. The emphasis in numerical simulation is given on finite element methods (FEM which is corrected by the response surface methodology (RSM. Aspects considered are effects of material parameters and variation in geometry. This paper describes our recent progress on FEM modeling of damages in concrete composite structures based on the TLS measurement. We also focus on the research about mechanical properties of concrete constructs here.

  7. Surface reconstruction and deformation monitoring of stratospheric airship based on laser scanning technology

    Science.gov (United States)

    Guo, Kai; Xie, Yongjie; Ye, Hu; Zhang, Song; Li, Yunfei

    2018-04-01

    Due to the uncertainty of stratospheric airship's shape and the security problem caused by the uncertainty, surface reconstruction and surface deformation monitoring of airship was conducted based on laser scanning technology and a √3-subdivision scheme based on Shepard interpolation was developed. Then, comparison was conducted between our subdivision scheme and the original √3-subdivision scheme. The result shows our subdivision scheme could reduce the shrinkage of surface and the number of narrow triangles. In addition, our subdivision scheme could keep the sharp features. So, surface reconstruction and surface deformation monitoring of airship could be conducted precisely by our subdivision scheme.

  8. Fabrication of microstructures in aviation components with a femtosecond laser based on PZT scanning

    International Nuclear Information System (INIS)

    Yang, Xiaojun; Zhao, Wei; Li, Ming; Yang, Yong; Cheng, Guanghua; Zhao, Hualong; Li, Peng; Zhang, Huixing

    2013-01-01

    Thermal defects and low precision are the main disadvantages of fabricating micro-holes, irregular holes, and micro-slots in thermostable aviation materials. We demonstrate a manufacturing method employing a femtosecond laser and piezoelectric ceramic (PZT). The production process parameters were optimized according to the metallographic and dimensional accuracy of the microstructure, which was measured by phase-contrast microscopy and scanning electron microscopy. The limitations in a conventional aeroengine, such as in the recast layer, recrystallization, and micro-cracks, which degrade the performance and service life, were resolved with a simple, controllable, and commercial method. (paper)

  9. Embryological study of Herminium monorchis (Orchidaceae) using confocal scanning laser microscopy

    International Nuclear Information System (INIS)

    Fredrikson, M.

    1990-01-01

    The embryology of Herminium monorchis (Orchidaceae) was studied using confocal scanning laser microscopy (CSLM), a new technique for embryological studies. This technique may contribute new information to plant embryology. Herminium monorchis has a monosporic embryo sac development. The mature embryo sac is 8-nucleate. Two integuments, both 2-layered, are formed, but only the inner takes part in formation of the micropyle. Double fertilization takes place. The primary endosperm nucleus does not divide, but remains alive at least at the 3-celled stage of embryo development. The three antipodals do not show any sign of degeneration at this stage. (author)

  10. Evaluation of Yogurt Microstructure Using Confocal Laser Scanning Microscopy and Image Analysis

    DEFF Research Database (Denmark)

    Skytte, Jacob Lercke; Ghita, Ovidiu; Whelan, Paul F.

    2015-01-01

    The microstructure of protein networks in yogurts defines important physical properties of the yogurt and hereby partly its quality. Imaging this protein network using confocal scanning laser microscopy (CSLM) has shown good results, and CSLM has become a standard measuring technique for fermented...... to image texture description. Here, CSLM images from a yogurt fermentation study are investigated, where production factors including fat content, protein content, heat treatment, and incubation temperature are varied. The descriptors are evaluated through nearest neighbor classification, variance analysis...... scanning microscopy images can be used to provide information on the protein microstructure in yogurt products. For large numbers of microscopy images, subjective evaluation becomes a difficult or even impossible approach, if the images should be incorporated in any form of statistical analysis alongside...

  11. A cryogenic scanning laser microscope for investigation of dynamical states in long Josephson junctions

    DEFF Research Database (Denmark)

    Holm, Jesper; Mygind, Jesper

    1995-01-01

    on measurements on different oscillator samples, performed with a novel Cryogenic Scanning Laser Microscope (CSLM) having a spatial resolution of less than ±2.5 μm over a 500 μm×50 μm wide scanning area in the temperature range 2 K-300 K. Even though the dynamical states are extremely sensitive to external noise...... tunnel current is one of the most important internal junction parameters which together with the boundary conditions determine the dynamics, it is of vital importance to experimentally determine the current density throughout the entire junction with high spatial resolution. Here we report...... this microscope enables us to make stable in-situ measurements on operating Josephson junctions. Recent results are presented and discussed....

  12. 3D model assisted fully automated scanning laser Doppler vibrometer measurements

    Science.gov (United States)

    Sels, Seppe; Ribbens, Bart; Bogaerts, Boris; Peeters, Jeroen; Vanlanduit, Steve

    2017-12-01

    In this paper, a new fully automated scanning laser Doppler vibrometer (LDV) measurement technique is presented. In contrast to existing scanning LDV techniques which use a 2D camera for the manual selection of sample points, we use a 3D Time-of-Flight camera in combination with a CAD file of the test object to automatically obtain measurements at pre-defined locations. The proposed procedure allows users to test prototypes in a shorter time because physical measurement locations are determined without user interaction. Another benefit from this methodology is that it incorporates automatic mapping between a CAD model and the vibration measurements. This mapping can be used to visualize measurements directly on a 3D CAD model. The proposed method is illustrated with vibration measurements of an unmanned aerial vehicle

  13. Analysis of polymer grafted inside the porous hydrogel using confocal laser scanning microscopy

    Directory of Open Access Journals (Sweden)

    2007-04-01

    Full Text Available Graft polymerization of glycidyl methacrylate onto the pore surface of polyacrylamide macroporous gel was implemented in DMSO-aqueous solution using diperiodatocuprate(III complexes as an initiator. The grafting densities up to 410% were achieved. The graft polymerization was confirmed by gravimetrical methods and FTIR. The graft polymerization of polymer inside the pores of the macroporous gel resulted in increased flow resistance through the gel matrix. The distribution of grafted polymer on the gel pore surface material was studied by scanning electron microscopy (SEM and confocal laser scanning microscopy (CLSM. CLSM is an alternative method for studying morphology of gel surface with grafted polymer having the advantages over the SEM allowing to investigate the distribution of grafted polymer inside the hydrogel in a native hydrated state. The microscopic techniques demonstrated uneven distribution of the grafted polymer inside the gel pores as a result of initiating the graft polymerization by insoluble initiator deposited on the pore surface.

  14. Use of laser-scan technology to analyse topography and flow in a weir pool

    Directory of Open Access Journals (Sweden)

    P. E. Dresel

    2012-08-01

    Full Text Available The development of laser-scan techniques provides opportunity for detailed terrain analysis in hydrologic studies. Ground based scans were used to model the ground surface elevation in the area of a stream gauge weir over an area of 240 m2 at a resolution of 0.05 m. The terrain model was used to assess the possibility of flow bypassing the weir and to calculate stream flow during filling of the weir pool, prior to flow through the weir notch. The mapped surface shows a subtle low-lying area at the south end of the structure where flow could bypass the weir. The flow calculations quantify low-flows that do not reach the weir notch during small rain events and flow at the beginning of larger events in the ephemeral stream.

  15. Static terrestrial laser scanning of juvenile understory trees for field phenotyping

    Science.gov (United States)

    Wang, Huanhuan; Lin, Yi

    2014-11-01

    This study was to attempt the cutting-edge 3D remote sensing technique of static terrestrial laser scanning (TLS) for parametric 3D reconstruction of juvenile understory trees. The data for test was collected with a Leica HDS6100 TLS system in a single-scan way. The geometrical structures of juvenile understory trees are extracted by model fitting. Cones are used to model trunks and branches. Principal component analysis (PCA) is adopted to calculate their major axes. Coordinate transformation and orthogonal projection are used to estimate the parameters of the cones. Then, AutoCAD is utilized to simulate the morphological characteristics of the understory trees, and to add secondary branches and leaves in a random way. Comparison of the reference values and the estimated values gives the regression equation and shows that the proposed algorithm of extracting parameters is credible. The results have basically verified the applicability of TLS for field phenotyping of juvenile understory trees.

  16. A cost-effective laser scanning method for mapping stream channel geometry and roughness

    Science.gov (United States)

    Lam, Norris; Nathanson, Marcus; Lundgren, Niclas; Rehnström, Robin; Lyon, Steve

    2015-04-01

    In this pilot project, we combine an Arduino Uno and SICK LMS111 outdoor laser ranging camera to acquire high resolution topographic area scans for a stream channel. The microprocessor and imaging system was installed in a custom gondola and suspended from a wire cable system. To demonstrate the systems capabilities for capturing stream channel topography, a small stream (< 2m wide) in the Krycklan Catchment Study was temporarily diverted and scanned. Area scans along the stream channel resulted in a point spacing of 4mm and a point cloud density of 5600 points/m2 for the 5m by 2m area. A grain size distribution of the streambed material was extracted from the point cloud using a moving window, local maxima search algorithm. The median, 84th and 90th percentiles (common metrics to describe channel roughness) of this distribution were found to be within the range of measured values while the largest modelled element was approximately 35% smaller than its measured counterpart. The laser scanning system captured grain sizes between 30mm and 255mm (coarse gravel/pebbles and boulders based on the Wentworth (1922) scale). This demonstrates that our system was capable of resolving both large-scale geometry (e.g. bed slope and stream channel width) and small-scale channel roughness elements (e.g. coarse gravel/pebbles and boulders) for the study area. We further show that the point cloud resolution is suitable for estimating ecohydraulic parameters such as Manning's n and hydraulic radius. Although more work is needed to fine-tune our system's design, these preliminary results are encouraging, specifically for those with a limited operational budget.

  17. Deriving Fuel Mass by Size Class in Douglas-fir (Pseudotsuga menziesii Using Terrestrial Laser Scanning

    Directory of Open Access Journals (Sweden)

    Lloyd Queen

    2011-08-01

    Full Text Available Requirements for describing coniferous forests are changing in response to wildfire concerns, bio-energy needs, and climate change interests. At the same time, technology advancements are transforming how forest properties can be measured. Terrestrial Laser Scanning (TLS is yielding promising results for measuring tree biomass parameters that, historically, have required costly destructive sampling and resulted in small sample sizes. Here we investigate whether TLS intensity data can be used to distinguish foliage and small branches (≤0.635 cm diameter; coincident with the one-hour timelag fuel size class from larger branchwood (>0.635 cm in Douglas-fir (Pseudotsuga menziesii branch specimens. We also consider the use of laser density for predicting biomass by size class. Measurements are addressed across multiple ranges and scan angles. Results show TLS capable of distinguishing fine fuels from branches at a threshold of one standard deviation above mean intensity. Additionally, the relationship between return density and biomass is linear by fuel type for fine fuels (r2 = 0.898; SE 22.7% and branchwood (r2 = 0.937; SE 28.9%, as well as for total mass (r2 = 0.940; SE 25.5%. Intensity decays predictably as scan distances increase; however, the range-intensity relationship is best described by an exponential model rather than 1/d2. Scan angle appears to have no systematic effect on fine fuel discrimination, while some differences are observed in density-mass relationships with changing angles due to shadowing.

  18. Micron-scale mapping of megagauss magnetic fields using optical polarimetry to probe hot electron transport in petawatt-class laser-solid interactions.

    Science.gov (United States)

    Chatterjee, Gourab; Singh, Prashant Kumar; Robinson, A P L; Blackman, D; Booth, N; Culfa, O; Dance, R J; Gizzi, L A; Gray, R J; Green, J S; Koester, P; Kumar, G Ravindra; Labate, L; Lad, Amit D; Lancaster, K L; Pasley, J; Woolsey, N C; Rajeev, P P

    2017-08-21

    The transport of hot, relativistic electrons produced by the interaction of an intense petawatt laser pulse with a solid has garnered interest due to its potential application in the development of innovative x-ray sources and ion-acceleration schemes. We report on spatially and temporally resolved measurements of megagauss magnetic fields at the rear of a 50-μm thick plastic target, irradiated by a multi-picosecond petawatt laser pulse at an incident intensity of ~10 20 W/cm 2 . The pump-probe polarimetric measurements with micron-scale spatial resolution reveal the dynamics of the magnetic fields generated by the hot electron distribution at the target rear. An annular magnetic field profile was observed ~5 ps after the interaction, indicating a relatively smooth hot electron distribution at the rear-side of the plastic target. This is contrary to previous time-integrated measurements, which infer that such targets will produce highly structured hot electron transport. We measured large-scale filamentation of the hot electron distribution at the target rear only at later time-scales of ~10 ps, resulting in a commensurate large-scale filamentation of the magnetic field profile. Three-dimensional hybrid simulations corroborate our experimental observations and demonstrate a beam-like hot electron transport at initial time-scales that may be attributed to the local resistivity profile at the target rear.

  19. Efficient Ways to Learn Weather Radar Polarimetry

    Science.gov (United States)

    Cao, Qing; Yeary, M. B.; Zhang, Guifu

    2012-01-01

    The U.S. weather radar network is currently being upgraded with dual-polarization capability. Weather radar polarimetry is an interdisciplinary area of engineering and meteorology. This paper presents efficient ways to learn weather radar polarimetry through several basic and practical topics. These topics include: 1) hydrometeor scattering model…

  20. Accuracy assessment of modeling architectural structures and details using terrestrial laser scanning

    Directory of Open Access Journals (Sweden)

    M. Kedzierski

    2015-08-01

    Full Text Available One of the most important aspects when performing architectural documentation of cultural heritage structures is the accuracy of both the data and the products which are generated from these data: documentation in the form of 3D models or vector drawings. The paper describes an assessment of the accuracy of modelling data acquired using a terrestrial phase scanner in relation to the density of a point cloud representing the surface of different types of construction materials typical for cultural heritage structures. This analysis includes the impact of the scanning geometry: the incidence angle of the laser beam and the scanning distance. For the purposes of this research, a test field consisting of samples of different types of construction materials (brick, wood, plastic, plaster, a ceramic tile, sheet metal was built. The study involved conducting measurements at different angles and from a range of distances for chosen scanning densities. Data, acquired in the form of point clouds, were then filtered and modelled. An accuracy assessment of the 3D model was conducted by fitting it with the point cloud. The reflection intensity of each type of material was also analyzed, trying to determine which construction materials have the highest reflectance coefficients, and which have the lowest reflection coefficients, and in turn how this variable changes for different scanning parameters. Additionally measurements were taken of a fragment of a building in order to compare the results obtained in laboratory conditions, with those taken in field conditions.

  1. Cryogenic scanning laser microscopy. Investigation of large BSCCO mesas and development of a polarizing microscope

    International Nuclear Information System (INIS)

    Guenon, Stefan Alexander

    2011-01-01

    This thesis is divided into two parts. Concerning the first part: Motivated by the discovery of coherent Terahertz emission from large sized Bi_2Sr_2CaCu_2O_8 stacks of intrinsic Josephson Junctions by Ozyuzer et al., low-temperature laser scanning microscopy (LTSLM) was used to investigate similar samples. In LTSLM a focused laser beam at position (x,y) is heating the sample in its vicinity. Simultaneously the electrical resistance of the sample is monitored by 4- or 2-wire sensing. By blanking the laser beam and using lock-in technique the response, i.e., the beam induced voltage change ΔV(x,y) to the heat distribution at the location (x,y) can be detected. Scanning the laser beam and mapping the response ΔV(x,y) leads to the so-called voltage image of the sample. Depending on the sample under investigation this voltage image is a map of all kinds of physical properties. This experimental technique was used with two objectives. First, the plasma wave causing the THz emission should be imaged, and second, the phenomenon of self-heating, which is considerable for large mesas, should be investigated. Indeed, it was possible to map a standing wave pattern at bias points with low currents, where Ozyuzer et al. have detected THz radiation. At high currents, where the back bending in the current-voltage relation indicates strong self heating, a feature appears in the LTSLM voltage images, which was clearly identified as an electro-thermal domain (hot spot) created by the temperature dependence of the c-axis resistivity in the Bi_2Sr_2CaCu_2O_8-mesa. In this bias interval a standing wave pattern appears beside this feature at certain bias points. In order to investigate whether this standing wave pattern is associated with THz emission, a simple interferometer with a bolometer as detector was realized. With the help of this set-up it was possible to detect THz radiation from mesas at high bias currents (hot spot bias regime) and to determine its frequency. It could be

  2. Nonperturbative measurement of the local magnetic field using pulsed polarimetry for fusion reactor conditions (invited)

    International Nuclear Information System (INIS)

    Smith, Roger J.

    2008-01-01

    A novel diagnostic technique for the remote and nonperturbative sensing of the local magnetic field in reactor relevant plasmas is presented. Pulsed polarimetry [Patent No. 12/150,169 (pending)] combines optical scattering with the Faraday effect. The polarimetric light detection and ranging (LIDAR)-like diagnostic has the potential to be a local B pol diagnostic on ITER and can achieve spatial resolutions of millimeters on high energy density (HED) plasmas using existing lasers. The pulsed polarimetry method is based on nonlocal measurements and subtle effects are introduced that are not present in either cw polarimetry or Thomson scattering LIDAR. Important features include the capability of simultaneously measuring local T e , n e , and B || along the line of sight, a resiliency to refractive effects, a short measurement duration providing near instantaneous data in time, and location for real-time feedback and control of magnetohydrodynamic (MHD) instabilities and the realization of a widely applicable internal magnetic field diagnostic for the magnetic fusion energy program. The technique improves for higher n e B || product and higher n e and is well suited for diagnosing the transient plasmas in the HED program. Larger devices such as ITER and DEMO are also better suited to the technique, allowing longer pulse lengths and thereby relaxing key technology constraints making pulsed polarimetry a valuable asset for next step devices. The pulsed polarimetry technique is clarified by way of illustration on the ITER tokamak and plasmas within the magnetized target fusion program within present technological means.

  3. Scanning pattern angle effect on the resulting properties of selective laser sintered monolayers of Cu-Sn-Ni powder

    Science.gov (United States)

    Sabelle, Matías; Walczak, Magdalena; Ramos-Grez, Jorge

    2018-01-01

    Laser-based layer manufacturing of metals, also known as additive manufacturing, is a growing research field of academic and industrial interest. However, in the associated laser-driven processes (i.e. selective laser sintering (SLS) or melting (SLM)), optimization of some parameters has not been fully explored. This research aims at determining how the angle of laser scanning pattern (i.e. build orientation) in SLS affects the mechanical properties and structure of an individual Cu-Sn-Ni alloy metallic layer sintered in the process. Experiments consist in varying the angle of the scanning pattern (0°, 30°, 45° 60° and 90° relative to the transverse dimension of the piece), at constant scanning speed and laser beam power, producing specimens of different thicknesses. A noticeable effect of the scan angle on the mechanical strength and degree of densification of the sintered specimens is found. Thickness of the resulting monolayer correlates negatively with increasing scan angle, whereas relative density correlates positively. A minimum porosity and maximum UTS are found at the angle of 60°. It is concluded that angle of the scanning pattern angle plays a significant role in SLS of metallic monolayers.

  4. Not all trees sleep the same - High temporal resolution terrestrial laser scanning shows differences in nocturnal plant movement

    DEFF Research Database (Denmark)

    Zlinszky, András; Barfod, Anders; Molnár, Bence

    2017-01-01

    Circadian leaf movements are widely known in plants, but nocturnal movement of tree branches were only recently discovered by using terrestrial laser scanning (TLS), a high resolution three-dimensional surveying technique. TLS uses a pulsed laser emitted in a regular scan pattern for rapid...... surveyed a series of 18 full scans over a 12-h night period to measure nocturnal changes in shape simultaneously for an experimental setup of 22 plants representing different species. Resulting point clouds were evaluated by comparing changes in height percentiles of laser scanning points belonging...... to the canopy. Changes in crown shape were observed for all studied trees, but clearly distinguishable sleep movements are apparently rare. Ambient light conditions were continuously dark between sunset (7:30 p.m.) and sunrise (6:00 a.m.), but most changes in movement direction occurred during this period, thus...

  5. TESTING OF LAND COVER CLASSIFICATION FROM MULTISPECTRAL AIRBORNE LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    K. Bakuła

    2016-06-01

    Full Text Available Multispectral Airborne Laser Scanning provides a new opportunity for airborne data collection. It provides high-density topographic surveying and is also a useful tool for land cover mapping. Use of a minimum of three intensity images from a multiwavelength laser scanner and 3D information included in the digital surface model has the potential for land cover/use classification and a discussion about the application of this type of data in land cover/use mapping has recently begun. In the test study, three laser reflectance intensity images (orthogonalized point cloud acquired in green, near-infrared and short-wave infrared bands, together with a digital surface model, were used in land cover/use classification where six classes were distinguished: water, sand and gravel, concrete and asphalt, low vegetation, trees and buildings. In the tested methods, different approaches for classification were applied: spectral (based only on laser reflectance intensity images, spectral with elevation data as additional input data, and spectro-textural, using morphological granulometry as a method of texture analysis of both types of data: spectral images and the digital surface model. The method of generating the intensity raster was also tested in the experiment. Reference data were created based on visual interpretation of ALS data and traditional optical aerial and satellite images. The results have shown that multispectral ALS data are unlike typical multispectral optical images, and they have a major potential for land cover/use classification. An overall accuracy of classification over 90% was achieved. The fusion of multi-wavelength laser intensity images and elevation data, with the additional use of textural information derived from granulometric analysis of images, helped to improve the accuracy of classification significantly. The method of interpolation for the intensity raster was not very helpful, and using intensity rasters with both first and

  6. Effect of Laser Power and Scan Speed on Melt Pool Characteristics of Commercially Pure Titanium (CP-Ti)

    Science.gov (United States)

    Kusuma, Chandrakanth; Ahmed, Sazzad H.; Mian, Ahsan; Srinivasan, Raghavan

    2017-07-01

    Selective laser melting (SLM) is an additive manufacturing technique that creates complex parts by selectively melting metal powder layer-by-layer using a laser. In SLM, the process parameters decide the quality of the fabricated component. In this study, single beads of commercially pure titanium (CP-Ti) were melted on a substrate of the same material using an in-house built SLM machine. Multiple combinations of laser power and scan speed were used for single bead fabrication, while the laser beam diameter and powder layer thickness were kept constant. This experimental study investigated the influence of laser power, scan speed, and laser energy density on the melt pool formation, surface morphology, geometry (width and height), and hardness of solidified beads. In addition, the observed unfavorable effect such as inconsistency in melt pool width formation is discussed. The results show that the quality, geometry, and hardness of solidified melt pool are significantly affected by laser power, scanning speed, and laser energy density.

  7. Iris ultrastructure in patients with synechiae as revealed by in vivo laser scanning confocal microscopy : In vivo iris ultrastructure in patients with Synechiae by Laser Scanning Confocal Microscopy.

    Science.gov (United States)

    Li, Ming; Cheng, Hongbo; Guo, Ping; Zhang, Chun; Tang, Song; Wang, Shusheng

    2016-04-26

    Iris plays important roles in ocular physiology and disease pathogenesis. Currently it is technically challenging to noninvasively examine the human iris ultrastructure in vivo. The purpose of the current study is to reveal human iris ultrastructure in patients with synechiae by using noninvasive in vivo laser scanning confocal microscopy (LSCM). The ultrastructure of iris in thirty one patients, each with synechiae but transparent cornea, was examined by in vivo LSCM. Five characteristic iris ultrastructures was revealed in patients with synechiae by in vivo LSCM, which include: 1. tree trunk-like structure; 2. tree branch/bush-like structure; 3. Fruit-like structure; 4. Epithelioid-like structure; 5. deep structure. Pigment granules can be observed as a loose structure on the top of the arborization structure. In iris-associated diseases with Tyndall's Phenomenon and keratic precipitates, the pigment particles are more likely to fall off from the arborization structure. The ultrastructure of iris in patients with synechiae has been visualized using in vivo LSCM. Five iris ultrastructures can be clearly observed, with some of the structures maybe disease-associated. The fall-off of the pigment particles may cause the Tyndall's Phenomenon positive. In vivo LSCM provides a non-invasive approach to observe the human iris ultrastructure under certain eye disease conditions, which sets up a foundation to visualize certain iris-associated diseases in the future.

  8. Comparison of the external physical damages between laser-assisted and mechanical immobilized human sperm using scanning electronic microscopy.

    Directory of Open Access Journals (Sweden)

    David Y L Chan

    Full Text Available We aim to visualize the external physical damages and distinct external phenotypic effects between mechanical and laser-assisted immobilized human spermatozoa using scanning electronic microscopy (SEM. Human spermatozoa were immobilized mechanically or with laser assistance for SEM examination and the membrane integrities were checked on both types of immobilized spermatozoa. We found evidence of external damages at SEM level on mechanically kinked sperm, but not on laser-assisted immobilized sperm. Although no external damage was found on laser-assist immobilized sperm, there were two distinct types of morphological changes when spermatozoa were stricken by infra-red laser. Coiled tails were immediately formed when Laser pulse was applied to the sperm end piece area, whereas laser applied to the sperm principal piece area resulted in a sharp bend of sperm tails. Sperm immobilized by laser did not exhibit any morphological change if the laser did not hit within the on-screen central target zone or if the laser hit the sperm mid piece or head. Our modified membrane integrity assay revealed that the external membrane of more than half of the laser-assisted immobilized sperm remained intact. In conclusion, mechanical immobilization produced membrane damages whilst laser-assisted immobilization did not result in any external membrane damages besides morphological changes at SEM level.

  9. A counting silicon microstrip detector for precision compton polarimetry

    CERN Document Server

    Doll, D W; Hillert, W; Krüger, H; Stammschroer, K; Wermes, N

    2002-01-01

    A detector for the detection of laser photons backscattered off an incident high-energy electron beam for precision Compton polarimetry in the 3.5 GeV electron stretcher ring ELSA at Bonn University has been developed using individual photon counting. The photon counting detector is based on a silicon microstrip detector system using dedicated ASIC chips. The produced hits by the pair converted Compton photons are accumulated rather than individually read out. A transverse profile displacement can be measured with mu m accuracy rendering a polarization measurement of the order of 1% on the time scale of 10-15 min possible.

  10. LIDAR AND INS FUSION IN PERIODS OF GPS OUTAGES FOR MOBILE LASER SCANNING MAPPING SYSTEMS

    Directory of Open Access Journals (Sweden)

    I. Klein

    2012-09-01

    Full Text Available Mobile laser scanning systems are becoming an increasingly popular means to obtain 3D coverage on a large scale. To perform the mapping, the exact position of the vehicle must be known throughout the trajectory. Exact position is achieved via integration of Global Positioning Systems (GPS and Inertial Navigation Systems (INS. Yet, in urban environments, cases of complete or even partial GPS outages may occur leaving the navigation solution to rely only on the INS. The INS navigation solution degrades with time as the Inertial Measurement Unit (IMU measurements contains noise, which permeates into the navigation equations. Degradation of the position determination leads to loss of data in such segments. To circumvent such drift and its effects, we propose fusing INS with lidar data by using building edges. This detection of edges is then translated into position data, which is used as an aiding to the INS. It thereby enables the determination of the vehicle position with a satisfactory level accuracy, sufficient to perform the laser-scanning based mapping in those outage periods.

  11. Assessment of Light Environment Variability in Broadleaved Forest Canopies Using Terrestrial Laser Scanning

    Directory of Open Access Journals (Sweden)

    Dimitry Van der Zande

    2010-06-01

    Full Text Available Light availability inside a forest canopy is of key importance to many ecosystem processes, such as photosynthesis and transpiration. Assessment of light availability and within-canopy light variability enables a more detailed understanding of these biophysical processes. The changing light-vegetation interaction in a homogeneous oak (Quercus robur L. stand was studied at different moments during the growth season using terrestrial laser scanning datasets and ray tracing technology. Three field campaigns were organized at regular time intervals (24 April 2008; 07 May 2008; 23 May 2008 to monitor the increase of foliage material. The laser scanning data was used to generate 3D representations of the forest stands, enabling structure feature extraction and light interception modeling, using the Voxel-Based Light Interception Model (VLIM. The VLIM is capable of estimating the relative light intensity or Percentage of Above Canopy Light (PACL at any arbitrary point in the modeled crown space. This resulted in a detailed description of the dynamic light environments inside the canopy. Mean vertical light extinction profiles were calculated for the three time frames, showing significant differences in light attenuation by the canopy between April 24 on the one hand, and May 7 and May 23 on the other hand. The proposed methodology created the opportunity to link these within-canopy light distributions to the increasing amount of photosynthetically active leaf material and its distribution in the considered 3D space.

  12. HIGH RESOLUTION AIRBORNE LASER SCANNING AND HYPERSPECTRAL IMAGING WITH A SMALL UAV PLATFORM

    Directory of Open Access Journals (Sweden)

    M. Gallay

    2016-06-01

    Full Text Available The capabilities of unmanned airborne systems (UAS have become diverse with the recent development of lightweight remote sensing instruments. In this paper, we demonstrate our custom integration of the state-of-the-art technologies within an unmanned aerial platform capable of high-resolution and high-accuracy laser scanning, hyperspectral imaging, and photographic imaging. The technological solution comprises the latest development of a completely autonomous, unmanned helicopter by Aeroscout, the Scout B1-100 UAV helicopter. The helicopter is powered by a gasoline two-stroke engine and it allows for integrating 18 kg of a customized payload unit. The whole system is modular providing flexibility of payload options, which comprises the main advantage of the UAS. The UAS integrates two kinds of payloads which can be altered. Both payloads integrate a GPS/IMU with a dual GPS antenna configuration provided by OXTS for accurate navigation and position measurements during the data acquisition. The first payload comprises a VUX-1 laser scanner by RIEGL and a Sony A6000 E-Mount photo camera. The second payload for hyperspectral scanning integrates a push-broom imager AISA KESTREL 10 by SPECIM. The UAS was designed for research of various aspects of landscape dynamics (landslides, erosion, flooding, or phenology in high spectral and spatial resolution.

  13. Characterization of particle deformation during compression measured by confocal laser scanning microscopy.

    Science.gov (United States)

    Guo, H X; Heinämäki, J; Yliruusi, J

    1999-09-20

    Direct compression of riboflavin sodium phosphate tablets was studied by confocal laser scanning microscopy (CLSM). The technique is non-invasive and generates three-dimensional (3D) images. Tablets of 1% riboflavin sodium phosphate with two grades of microcrystalline cellulose (MCC) were individually compressed at compression forces of 1.0 and 26.8 kN. The behaviour and deformation of drug particles on the upper and lower surfaces of the tablets were studied under compression forces. Even at the lower compression force, distinct recrystallized areas in the riboflavin sodium phosphate particles were observed in both Avicel PH-101 and Avicel PH-102 tablets. At the higher compression force, the recrystallization of riboflavin sodium phosphate was more extensive on the upper surface of the Avicel PH-102 tablet than the Avicel PH-101 tablet. The plastic deformation properties of both MCC grades reduced the fragmentation of riboflavin sodium phosphate particles. When compressed with MCC, riboflavin sodium phosphate behaved as a plastic material. The riboflavin sodium phosphate particles were more tightly bound on the upper surface of the tablet than on the lower surface, and this could also be clearly distinguished by CLSM. Drug deformation could not be visualized by other techniques. Confocal laser scanning microscopy provides valuable information on the internal mechanisms of direct compression of tablets.

  14. Feasibility of Machine Learning Methods for Separating Wood and Leaf Points from Terrestrial Laser Scanning Data

    Science.gov (United States)

    Wang, D.; Hollaus, M.; Pfeifer, N.

    2017-09-01

    Classification of wood and leaf components of trees is an essential prerequisite for deriving vital tree attributes, such as wood mass, leaf area index (LAI) and woody-to-total area. Laser scanning emerges to be a promising solution for such a request. Intensity based approaches are widely proposed, as different components of a tree can feature discriminatory optical properties at the operating wavelengths of a sensor system. For geometry based methods, machine learning algorithms are often used to separate wood and leaf points, by providing proper training samples. However, it remains unclear how the chosen machine learning classifier and features used would influence classification results. To this purpose, we compare four popular machine learning classifiers, namely Support Vector Machine (SVM), Na¨ıve Bayes (NB), Random Forest (RF), and Gaussian Mixture Model (GMM), for separating wood and leaf points from terrestrial laser scanning (TLS) data. Two trees, an Erytrophleum fordii and a Betula pendula (silver birch) are used to test the impacts from classifier, feature set, and training samples. Our results showed that RF is the best model in terms of accuracy, and local density related features are important. Experimental results confirmed the feasibility of machine learning algorithms for the reliable classification of wood and leaf points. It is also noted that our studies are based on isolated trees. Further tests should be performed on more tree species and data from more complex environments.

  15. FEASIBILITY OF MACHINE LEARNING METHODS FOR SEPARATING WOOD AND LEAF POINTS FROM TERRESTRIAL LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    D. Wang

    2017-09-01

    Full Text Available Classification of wood and leaf components of trees is an essential prerequisite for deriving vital tree attributes, such as wood mass, leaf area index (LAI and woody-to-total area. Laser scanning emerges to be a promising solution for such a request. Intensity based approaches are widely proposed, as different components of a tree can feature discriminatory optical properties at the operating wavelengths of a sensor system. For geometry based methods, machine learning algorithms are often used to separate wood and leaf points, by providing proper training samples. However, it remains unclear how the chosen machine learning classifier and features used would influence classification results. To this purpose, we compare four popular machine learning classifiers, namely Support Vector Machine (SVM, Na¨ıve Bayes (NB, Random Forest (RF, and Gaussian Mixture Model (GMM, for separating wood and leaf points from terrestrial laser scanning (TLS data. Two trees, an Erytrophleum fordii and a Betula pendula (silver birch are used to test the impacts from classifier, feature set, and training samples. Our results showed that RF is the best model in terms of accuracy, and local density related features are important. Experimental results confirmed the feasibility of machine learning algorithms for the reliable classification of wood and leaf points. It is also noted that our studies are based on isolated trees. Further tests should be performed on more tree species and data from more complex environments.

  16. Non-Linear Structural Dynamics Characterization using a Scanning Laser Vibrometer

    Science.gov (United States)

    Pai, P. F.; Lee, S.-Y.

    2003-01-01

    This paper presents the use of a scanning laser vibrometer and a signal decomposition method to characterize non-linear dynamics of highly flexible structures. A Polytec PI PSV-200 scanning laser vibrometer is used to measure transverse velocities of points on a structure subjected to a harmonic excitation. Velocity profiles at different times are constructed using the measured velocities, and then each velocity profile is decomposed using the first four linear mode shapes and a least-squares curve-fitting method. From the variations of the obtained modal \\ielocities with time we search for possible non-linear phenomena. A cantilevered titanium alloy beam subjected to harmonic base-excitations around the second. third, and fourth natural frequencies are examined in detail. Influences of the fixture mass. gravity. mass centers of mode shapes. and non-linearities are evaluated. Geometrically exact equations governing the planar, harmonic large-amplitude vibrations of beams are solved for operational deflection shapes using the multiple shooting method. Experimental results show the existence of 1:3 and 1:2:3 external and internal resonances. energy transfer from high-frequency modes to the first mode. and amplitude- and phase- modulation among several modes. Moreover, the existence of non-linear normal modes is found to be questionable.

  17. Tritium Removal from JET and TFTR Tiles by a Scanning Laser; TOPICAL

    International Nuclear Information System (INIS)

    C.H. Skinner; N. Bekris; J.P. Coad; C.A. Gentile; M. Glugla

    2002-01-01

    Fast and efficient tritium removal is needed for future D-T machines with carbon plasma-facing components. A novel method for tritium release has been demonstrated on co-deposited layers on tiles retrieved from the Tokamak Fusion Test Reactor (TFTR) and from the Joint European Torus (JET). A scanning continuous wave neodymium laser beam was focused to=100 W/mm2 and scanned at high speed over the co-deposits, heating them to temperatures=2000 C for about 10 ms in either air or argon atmospheres. Fiber optic coupling between the laser and scanner was implemented. Up to 87% of the co-deposited tritium was thermally desorbed from the JET and TFTR samples. This technique appears to be a promising in-situ method for tritium removal in a next-step D-T device as it avoids oxidation, the associated de-conditioning of the plasma-facing surfaces, and the expense of processing large quantities of tritium oxide

  18. Tritium Removal from JET and TFTR Tiles by a Scanning Laser

    International Nuclear Information System (INIS)

    Skinner, C.H.; Bekris, N.; Coad, J.P.; Gentile, C.A.; Glugla, M.

    2002-01-01

    Fast and efficient tritium removal is needed for future D-T machines with carbon plasma-facing components. A novel method for tritium release has been demonstrated on co-deposited layers on tiles retrieved from the Tokamak Fusion Test Reactor (TFTR) and from the Joint European Torus (JET). A scanning continuous wave neodymium laser beam was focused to =100 W/mm2 and scanned at high speed over the co-deposits, heating them to temperatures =2000 C for about 10 ms in either air or argon atmospheres. Fiber optic coupling between the laser and scanner was implemented. Up to 87% of the co-deposited tritium was thermally desorbed from the JET and TFTR samples. This technique appears to be a promising in-situ method for tritium removal in a next-step D-T device as it avoids oxidation, the associated de-conditioning of the plasma-facing surfaces, and the expense of processing large quantities of tritium oxide

  19. Application of scanning laser Doppler vibrometry for delamination detection in composite structures

    Science.gov (United States)

    Kudela, Pawel; Wandowski, Tomasz; Malinowski, Pawel; Ostachowicz, Wieslaw

    2017-12-01

    In this paper application of scanning laser Doppler vibrometry for delamination detection in composite structures was presented. Delamination detection was based on a guided wave propagation method. In this papers results from numerical and experimental research were presented. In the case of numerical research, the Spectral Element Method (SEM) was utilized, in which a mesh was composed of 3D spectral elements. SEM model included also a piezoelectric transducer. In the experimental research guided waves were excited using the piezoelectric transducer whereas the sensing process was conducted using scanning laser Doppler vibrometer (SLDV). Analysis of guided wave propagation and its interaction with delamination was based on a full wavefield approach. Attention was focused on interactions of guided waves with delamination manifested by A0 mode reflection, A0 mode entrapment, and S0/A0 mode conversion. Delamination was simulated by a teflon insert located between plies of composite material. Results of interaction with symmetrically and nonsymmetrical placed delamination (in respect to the composite sample thickness) were presented. Moreover, the authors investigated different size of delaminations. Damage detection was based on a new signal processing algorithm proposed by the authors. In this approach the weighted RMS was utilized selectively. It means that the summation in RMS formula was performed only for a specially selected time instances. Results for simple composite panels, panel with honeycomb core, and real stiffened composite panel from the aircraft were presented.

  20. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting

    Science.gov (United States)

    Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-01-01

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material. PMID:29443912

  1. Automatic segmentation of cell nuclei from confocal laser scanning microscopy images

    International Nuclear Information System (INIS)

    Kelemen, A.; Reist, H.W.

    1997-01-01

    A newly developed experimental method combines the possibility of irradiating more than a thousand cells simultaneous with an efficient colony-forming ability and with the capability of localizing a particle track through a cell nucleus together with the assessment of the energy transfer by digital superposition of the image containing the track with that of the cells. To assess the amount of energy deposition by particles traversing the cell nucleus the intersection lengths of the particle tracks have to be known. Intersection lengths can be obtained by determining the 3D surface contours of the irradiated cell nuclei. Confocal laser scanning microscopy using specific DNA fluorescent dye offers a possible way for the determination of the 3D shape of individual nuclei. Unfortunately, such experiments cannot be performed on living cells. One solution to this problem can be provided by building a statistical model of the shape of the nuclei of the exposed cells. In order to build such a statistical model, a large number of cell nuclei have to be identified and segmented from confocal laser scanning microscopy images. The present paper describes a method to perform this 3D segmentation in an automatic manner in order to create a solid basis for the statistical model. (author) 2 figs., 4 refs

  2. Application of laser scan microscopy in vivo for wound healing characterization

    International Nuclear Information System (INIS)

    Czaika, V; Koch, S; Alborova, A; Sterry, W; Lademann, J

    2010-01-01

    Considering the advancing age of the population, wound healing disturbances are becoming increasingly important in clinical routine. The development of wound healing creams and lotions as well as therapy control require an objective evaluation of the wound healing process, which represents the destruction of the barrier. Therefore, transepidermal water loss measurements are often carried out. These measurements have the disadvantage that they are disturbed by the interstitial fluid, which is located on the surface of chronic wounds and also by water components of the creams and lotions. Additionally, the TEWL measurements are very sensitive to temperature changes and to the anxiety of the volunteers. In the present study, in vivo laser scanning microscopy was used to analyze the reepithelialization and barrier recovery of standardized wounds produced by the suction blister technique. It was demonstrated that this non-invasive, on-line spectroscopic method allows the evaluation of the wound healing process, without any disturbances. It was found that the wound healing starts not only from the edges of the wound, but also out of the hair follicles. The in vivo laser scanning microscopy is well suited to evaluate the efficacy of wound healing creams and for therapy control

  3. Application of laser scan microscopy in vivo for wound healing characterization

    Science.gov (United States)

    Czaika, V.; Alborova, A.; Sterry, W.; Lademann, J.; Koch, S.

    2010-09-01

    Considering the advancing age of the population, wound healing disturbances are becoming increasingly important in clinical routine. The development of wound healing creams and lotions as well as therapy control require an objective evaluation of the wound healing process, which represents the destruction of the barrier. Therefore, transepidermal water loss measurements are often carried out. These measurements have the disadvantage that they are disturbed by the interstitial fluid, which is located on the surface of chronic wounds and also by water components of the creams and lotions. Additionally, the TEWL measurements are very sensitive to temperature changes and to the anxiety of the volunteers. In the present study, in vivo laser scanning microscopy was used to analyze the reepithelialization and barrier recovery of standardized wounds produced by the suction blister technique. It was demonstrated that this non-invasive, on-line spectroscopic method allows the evaluation of the wound healing process, without any disturbances. It was found that the wound healing starts not only from the edges of the wound, but also out of the hair follicles. The in vivo laser scanning microscopy is well suited to evaluate the efficacy of wound healing creams and for therapy control.

  4. Confocal laser scanning microscopy to estimate nanoparticles' human skin penetration in vitro.

    Science.gov (United States)

    Zou, Ying; Celli, Anna; Zhu, Hanjiang; Elmahdy, Akram; Cao, Yachao; Hui, Xiaoying; Maibach, Howard

    2017-01-01

    With rapid development of nanotechnology, there is increasing interest in nanoparticle (NP) application and its safety and efficacy on human skin. In this study, we utilized confocal laser scanning microscopy to estimate NP skin penetration. Three different-sized polystyrene NPs marked with red fluorescence were applied to human skin, and Calcium Green 5N was used as a counterstain. Dimethyl sulfoxide (DMSO) and ethanol were used as alternative vehicles for NPs. Tape stripping was utilized as a barrier-damaged skin model. Skin biopsies dosed with NPs were incubated at 4°C or 37°C for 24 hours and imaged using confocal laser scanning microscopy. NPs were localized in the stratum corneum (SC) and hair follicles without penetrating the epidermis/dermis. Barrier alteration with tape stripping and change in incubation temperature did not induce deeper penetration. DMSO enhanced NP SC penetration but ethanol did not. Except with DMSO vehicle, these hydrolyzed polystyrene NPs did not penetrate intact or barrier-damaged human "viable" epidermis. For further clinical relevance, in vivo human skin studies and more sensitive analytic chemical methodology are suggested.

  5. Confocal laser scanning microscopy to estimate nanoparticles’ human skin penetration in vitro

    Science.gov (United States)

    Elmahdy, Akram; Cao, Yachao; Hui, Xiaoying; Maibach, Howard

    2017-01-01

    Objective With rapid development of nanotechnology, there is increasing interest in nanoparticle (NP) application and its safety and efficacy on human skin. In this study, we utilized confocal laser scanning microscopy to estimate NP skin penetration. Methods Three different-sized polystyrene NPs marked with red fluorescence were applied to human skin, and Calcium Green 5N was used as a counterstain. Dimethyl sulfoxide (DMSO) and ethanol were used as alternative vehicles for NPs. Tape stripping was utilized as a barrier-damaged skin model. Skin biopsies dosed with NPs were incubated at 4°C or 37°C for 24 hours and imaged using confocal laser scanning microscopy. Results NPs were localized in the stratum corneum (SC) and hair follicles without penetrating the epidermis/dermis. Barrier alteration with tape stripping and change in incubation temperature did not induce deeper penetration. DMSO enhanced NP SC penetration but ethanol did not. Conclusion Except with DMSO vehicle, these hydrolyzed polystyrene NPs did not penetrate intact or barrier-damaged human “viable” epidermis. For further clinical relevance, in vivo human skin studies and more sensitive analytic chemical methodology are suggested. PMID:29184403

  6. Fine Deformation Monitoring of Ancient Building Based on Terrestrial Laser Scanning Technologies

    International Nuclear Information System (INIS)

    Wei, Zhou; Huadong, Guo; Qi, Li; Tianhua, Hong

    2014-01-01

    Laser scanning technology has been widely used to build high-precision three dimensional models in the preservation of ancient buildings. In this paper, we take the Tower of Buddhist Incense in the Summer Palace as our research subject. Combining laser scanning technologies with close-range photogrammetry, GIS and virtual reality technologies, we acquired comprehensive and high accuracy geospatial data of the tower, and built the 3D models with an average measurement error of a single point less than 2 millimeters and a registration error of 3D data less than 5 millimeters. After data registration of the whole tower with high-precision, deformation monitoring was conducted. Having been repaired many times, the cross-sections of the tower's pillars are not in a circular shape. In order to know the dip and dip direction of each pillar exactly, ellipse fitting algorithm was used to calculate the location of the centre of every pillar. And then, the coordinates of the pillars' centre points, the major and minor axes of the ellipses, and rotation angles were calculated. The technologies and methodology used in this paper could significantly contribute towards the long-term protection of endangered cultural relics using measurements and modelling with high-levels of scientific precision

  7. Effective Detection of Sub-Surface Archeological Features from Laser Scanning Point Clouds and Imagery Data

    Science.gov (United States)

    Fryskowska, A.; Kedzierski, M.; Walczykowski, P.; Wierzbicki, D.; Delis, P.; Lada, A.

    2017-08-01

    The archaeological heritage is non-renewable, and any invasive research or other actions leading to the intervention of mechanical or chemical into the ground lead to the destruction of the archaeological site in whole or in part. For this reason, modern archeology is looking for alternative methods of non-destructive and non-invasive methods of new objects identification. The concept of aerial archeology is relation between the presence of the archaeological site in the particular localization, and the phenomena that in the same place can be observed on the terrain surface form airborne platform. One of the most appreciated, moreover, extremely precise, methods of such measurements is airborne laser scanning. In research airborne laser scanning point cloud with a density of 5 points/sq. m was used. Additionally unmanned aerial vehicle imagery data was acquired. Test area is located in central Europe. The preliminary verification of potentially microstructures localization was the creation of digital terrain and surface models. These models gave an information about the differences in elevation, as well as regular shapes and sizes that can be related to the former settlement/sub-surface feature. The paper presents the results of the detection of potentially sub-surface microstructure fields in the forestry area.

  8. EFFECTIVE DETECTION OF SUB-SURFACE ARCHEOLOGICAL FEATURES FROM LASER SCANNING POINT CLOUDS AND IMAGERY DATA

    Directory of Open Access Journals (Sweden)

    A. Fryskowska

    2017-08-01

    Full Text Available The archaeological heritage is non-renewable, and any invasive research or other actions leading to the intervention of mechanical or chemical into the ground lead to the destruction of the archaeological site in whole or in part. For this reason, modern archeology is looking for alternative methods of non-destructive and non-invasive methods of new objects identification. The concept of aerial archeology is relation between the presence of the archaeological site in the particular localization, and the phenomena that in the same place can be observed on the terrain surface form airborne platform. One of the most appreciated, moreover, extremely precise, methods of such measurements is airborne laser scanning. In research airborne laser scanning point cloud with a density of 5 points/sq. m was used. Additionally unmanned aerial vehicle imagery data was acquired. Test area is located in central Europe. The preliminary verification of potentially microstructures localization was the creation of digital terrain and surface models. These models gave an information about the differences in elevation, as well as regular shapes and sizes that can be related to the former settlement/sub-surface feature. The paper presents the results of the detection of potentially sub-surface microstructure fields in the forestry area.

  9. QUANTIFICATION OF BIOFILMS IN MULTI-SPECTRAL DIGITAL1 VOLUMES FROM CONFOCAL LASER-SCANNING MICROSCOPES

    Directory of Open Access Journals (Sweden)

    Karsten Rodenacker

    2011-05-01

    Full Text Available Populations of bacteria in sludge flocs and biofilm marked by fluorescence marked with fluorescent probes are digitised with a confocal laser scanning microscope. These data are used to analyse the microbial community structure, to obtain information on the localisation of specific bacterial groups and to examine gene expression. This information is urgently required for an in-depth understanding of the function and, more generally, the microbial ecology of biofilms. Methods derived from quantitative image analysis are applied to digitised data from confocal laser scanning microscopes to obtain quantitative descriptions of volumetric, topological (and topographical properties of different compartments of the components under research. In addition to free-moving flocs, also biofilms attached to a substratum in an experimental environment are analysed. Growth form as well as interaction of components are quantitatively described. Classical measurements of volume and intensity (shape, distribution and distance dependent interaction measurements using methods from mathematical morphology are performed. Mainly image (volume processing methods are outlined. Segmented volumes are globally and individually (in terms of 3Dconnected components measured and used for distance mapping transform as well as for estimation of geodesic distances from the substrate. All transformations are applied on the 3D data set. Resulting distance distributions are quantified and related to information on the identity and activity of the probe-identified bacteria.

  10. MICROSTRUCTURE AND MECHANICAL STRENGTH OF SURFACE ODS TREATED ZIRCALOY-4 SHEET USING LASER BEAM SCANNING

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    HYUN-GIL KIM

    2014-08-01

    Full Text Available The surface modification of engineering materials by laser beam scanning (LBS allows the improvement of properties in terms of reduced wear, increased corrosion resistance, and better strength. In this study, the laser beam scan method was applied to produce an oxide dispersion strengthened (ODS structure on a zirconium metal surface. A recrystallized Zircaloy-4 alloy sheet with a thickness of 2 mm, and Y2O3 particles of 10 μm were selected for ODS treatment using LBS. Through the LBS method, the Y2O3 particles were dispersed in the Zircaloy-4 sheet surface at a thickness of 0.4 mm, which was about 20% when compared to the initial sheet thickness. The mean size of the dispersive particles was 20 nm, and the yield strength of the ODS treated plate at 500°C was increased more than 65 % when compared to the initial state. This strength increase was caused by dispersive Y2O3 particles in the matrix and the martensite transformation of Zircaloy-4 matrix by the LBS.

  11. Performance analysis of a compact and low-cost mapping-grade mobile laser scanning system

    Science.gov (United States)

    Julge, Kalev; Vajakas, Toivo; Ellmann, Artu

    2017-10-01

    The performance of a low-cost, self-contained, compact, and easy to deploy mapping-grade mobile laser scanning (MLS) system, which is composed of a light detection and ranging sensor Velodyne VLP-16 and a dual antenna global navigation satellite system/inertial navigation system SBG Systems Ellipse-D, is analyzed. The field tests were carried out in car-mounted and backpack modes for surveying road engineering structures (such as roads, parking lots, underpasses, and tunnels) and coastal erosion zones, respectively. The impact of applied calculation principles on trajectory postprocessing, direct georeferencing, and the theoretical accuracy of the system is analyzed. A calibration method, based on Bound Optimization BY Quadratic Approximation, for finding the boresight angles of an MLS system is proposed. The resulting MLS point clouds are compared with high-accuracy static terrestrial laser scanning data and survey-grade MLS data from a commercially manufactured MLS system. The vertical, horizontal, and relative accuracy are assessed-the root-mean-square error (RMSE) values were determined to be 8, 15, and 3 cm, respectively. Thus, the achieved mapping-grade accuracy demonstrates that this relatively compact and inexpensive self-assembled MLS can be successfully used for surveying the geometry and deformations of terrain, buildings, road, and other engineering structures.

  12. Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

    Science.gov (United States)

    Gallay, Michal; Hochmuth, Zdenko; Kaňuk, Ján; Hofierka, Jaroslav

    2016-05-01

    The change of hydrological conditions during the evolution of caves in carbonate rocks often results in a complex subterranean geomorphology, which comprises specific landforms such as ceiling channels, anastomosing half tubes, or speleothems organized vertically in different levels. Studying such complex environments traditionally requires tedious mapping; however, this is being replaced with terrestrial laser scanning technology. Laser scanning overcomes the problem of reaching high ceilings, providing new options to map underground landscapes with unprecedented level of detail and accuracy. The acquired point cloud can be handled conveniently with dedicated software, but applying traditional geomorphometry to analyse the cave surface is limited. This is because geomorphometry has been focused on parameterization and analysis of surficial terrain. The theoretical and methodological concept has been based on two-dimensional (2-D) scalar fields, which are sufficient for most cases of the surficial terrain. The terrain surface is modelled with a bivariate function of altitude (elevation) and represented by a raster digital elevation model. However, the cave is a 3-D entity; therefore, a different approach is required for geomorphometric analysis. In this paper, we demonstrate the benefits of high-resolution cave mapping and 3-D modelling to better understand the palaeohydrography of the Domica cave in Slovakia. This methodological approach adopted traditional geomorphometric methods in a unique manner and also new methods used in 3-D computer graphics, which can be applied to study other 3-D geomorphological forms.

  13. Scanning laser optical tomography for in toto imaging of the murine cochlea.

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    Lena Nolte

    Full Text Available The mammalian cochlea is a complex macroscopic structure due to its helical shape and the microscopic arrangements of the individual layers of cells. To improve the outcomes of hearing restoration in deaf patients, it is important to understand the anatomic structure and composition of the cochlea ex vivo. Hitherto, only one histological technique based on confocal laser scanning microscopy and optical clearing has been developed for in toto optical imaging of the murine cochlea. However, with a growing size of the specimen, e.g., human cochlea, this technique reaches its limitations. Here, we demonstrate scanning laser optical tomography (SLOT as a valuable imaging technique to visualize the murine cochlea in toto without any physical slicing. This technique can also be applied in larger specimens up to cm3 such as the human cochlea. Furthermore, immunolabeling allows visualization of inner hair cells (otoferlin or spiral ganglion cells (neurofilament within the whole cochlea. After image reconstruction, the 3D dataset was used for digital segmentation of the labeled region. As a result, quantitative analysis of position, length and curvature of the labeled region was possible. This is of high interest in order to understand the interaction of cochlear implants (CI and cells in more detail.

  14. Axial Fan Blade Vibration Assessment under Inlet Cross-Flow Conditions Using Laser Scanning Vibrometry

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    Till Heinemann

    2017-08-01

    Full Text Available In thermal power plants equipped with air-cooled condensers (ACCs, axial cooling fans operate under the influence of ambient flow fields. Under inlet cross-flow conditions, the resultant asymmetric flow field is known to introduce additional harmonic forces to the fan blades. This effect has previously only been studied numerically or by using blade-mounted strain gauges. For this study, laser scanning vibrometry (LSV was used to assess fan blade vibration under inlet cross-flow conditions in an adapted fan test rig inside a wind tunnel test section. Two co-rotating laser beams scanned a low-pressure axial fan, resulting in spectral, phase-resolved surface vibration patterns of the fan blades. Two distinct operating points with flow coefficients of 0.17 and 0.28 were examined, with and without inlet cross-flow influence. While almost identical fan vibration patterns were found for both reference operating points, the overall blade vibration increased by 100% at the low fan flow rate as a result of cross-flow, and by 20% at the high fan flow rate. While numerically predicted natural frequency modes could be confirmed from experimental data as minor peaks in the vibration amplitude spectrum, they were not excited significantly by cross-flow. Instead, primarily higher rotation-rate harmonics were amplified; that is, a synchronous blade-tip flapping was strongly excited at the blade-pass frequency.

  15. Extraction of Vertical Walls from Mobile Laser Scanning Data for Solar Potential Assessment

    Directory of Open Access Journals (Sweden)

    Martin Rutzinger

    2011-03-01

    Full Text Available In recent years there has been an increasing demand among home owners for cost effective sustainable energy production such as solar energy to provide heating and electricity. A lot of research has focused on the assessment of the incoming solar radiation on roof planes acquired by, e.g., Airborne Laser Scanning (ALS. However, solar panels can also be mounted on building facades in order to increase renewable energy supply. Due to limited reflections of points from vertical walls, ALS data is not suitable to perform solar potential assessment of vertical building facades. This paper focuses on a new method for automatic solar radiation modeling of facades acquired by Mobile Laser Scanning (MLS and uses the full 3D information of the point cloud for both the extraction of vertical walls covered by the survey and solar potential analysis. Furthermore, a new method isintroduced determining the interior and exterior face, respectively, of each detected wall in order to calculate its slope and aspect angles that are of crucial importance for solar potential assessment. Shadowing effects of nearby objects are considered by computing the 3D horizon of each point of a facade segment within the 3D point cloud.

  16. Compact Multipurpose Mobile Laser Scanning System — Initial Tests and Results

    Directory of Open Access Journals (Sweden)

    Craig Glennie

    2013-01-01

    Full Text Available We describe a prototype compact mobile laser scanning system that may be operated from a backpack or unmanned aerial vehicle. The system is small, self-contained, relatively inexpensive, and easy to deploy. A description of system components is presented, along with the initial calibration of the multi-sensor platform. The first field tests of the system, both in backpack mode and mounted on a helium balloon for real-world applications are presented. For both field tests, the acquired kinematic LiDAR data are compared with highly accurate static terrestrial laser scanning point clouds. These initial results show that the vertical accuracy of the point cloud for the prototype system is approximately 4 cm (1σ in balloon mode, and 3 cm (1σ in backpack mode while horizontal accuracy was approximately 17 cm (1σ for the balloon tests. Results from selected study areas on the Sacramento River Delta and San Andreas Fault in California demonstrate system performance, deployment agility and flexibility, and potential for operational production of high density and highly accurate point cloud data. Cost and production rate trade-offs place this system in the niche between existing airborne and tripod mounted LiDAR systems.

  17. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting.

    Science.gov (United States)

    Koutny, Daniel; Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-02-14

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material.

  18. Characterisation of Intensity Values on Terrestrial Laser Scanning for Recording Enhancement

    Science.gov (United States)

    Balaguer-Puig, M.; Molada-Tebar, A.; Marqués-Mateu, A.; Lerma, J. L.

    2017-08-01

    Mapping surveys based on terrestrial laser scanning (TLS) are common nowadays for different purposes such as documentation of cultural heritage assets. The chance to extract relevant information from TLS surveys depends not only on the fast acquisition of XYZ coordinates, but also on the meaningful intensity values of the fired objects. TLS behaviour depends on several known factors such as distance, texture, roughness, colour and albedo. This paper seeks to find out the mathematical relationship between the TLS intensity values and the colorimetric data using a colour chart. In order to do so, objective colour specification based on well-known colour spaces is needed. The approach used here started with scanning a colour chart containing a number of colour patches with known chromatic and reflection characteristics. After several transformations, the results allowed us to characterise the intensity behaviour of a time-of-flight laser scanner. The characterisation of the intensity values are tested indoor on the colour chart and outdoor on an archaeological shelter. Promising results are obtained to enhance the behaviour of the intensity values coming from the TLS.

  19. A spatio-temporal index for aerial full waveform laser scanning data

    Science.gov (United States)

    Laefer, Debra F.; Vo, Anh-Vu; Bertolotto, Michela

    2018-04-01

    Aerial laser scanning is increasingly available in the full waveform version of the raw signal, which can provide greater insight into and control over the data and, thus, richer information about the scanned scenes. However, when compared to conventional discrete point storage, preserving raw waveforms leads to vastly larger and more complex data volumes. To begin addressing these challenges, this paper introduces a novel bi-level approach for storing and indexing full waveform (FWF) laser scanning data in a relational database environment, while considering both the spatial and the temporal dimensions of that data. In the storage scheme's upper level, the full waveform datasets are partitioned into spatial and temporal coherent groups that are indexed by a two-dimensional R∗-tree. To further accelerate intra-block data retrieval, at the lower level a three-dimensional local octree is created for each pulse block. The local octrees are implemented in-memory and can be efficiently written to a database for reuse. The indexing solution enables scalable and efficient three-dimensional (3D) spatial and spatio-temporal queries on the actual pulse data - functionalities not available in other systems. The proposed FWF laser scanning data solution is capable of managing multiple FWF datasets derived from large flight missions. The flight structure is embedded into the data storage model and can be used for querying predicates. Such functionality is important to FWF data exploration since aircraft locations and orientations are frequently required for FWF data analyses. Empirical tests on real datasets of up to 1 billion pulses from Dublin, Ireland prove the almost perfect scalability of the system. The use of the local 3D octree in the indexing structure accelerated pulse clipping by 1.2-3.5 times for non-axis-aligned (NAA) polyhedron shaped clipping windows, while axis-aligned (AA) polyhedron clipping was better served using only the top indexing layer. The distinct

  20. Automatic registration of panoramic image sequence and mobile laser scanning data using semantic features

    Science.gov (United States)

    Li, Jianping; Yang, Bisheng; Chen, Chi; Huang, Ronggang; Dong, Zhen; Xiao, Wen

    2018-02-01

    Inaccurate exterior orientation parameters (EoPs) between sensors obtained by pre-calibration leads to failure of registration between panoramic image sequence and mobile laser scanning data. To address this challenge, this paper proposes an automatic registration method based on semantic features extracted from panoramic images and point clouds. Firstly, accurate rotation parameters between the panoramic camera and the laser scanner are estimated using GPS and IMU aided structure from motion (SfM). The initial EoPs of panoramic images are obtained at the same time. Secondly, vehicles in panoramic images are extracted by the Faster-RCNN as candidate primitives to be matched with potential corresponding primitives in point clouds according to the initial EoPs. Finally, translation between the panoramic camera and the laser scanner is refined by maximizing the overlapping area of corresponding primitive pairs based on the Particle Swarm Optimization (PSO), resulting in a finer registration between panoramic image sequences and point clouds. Two challenging urban scenes were experimented to assess the proposed method, and the final registration errors of these two scenes were both less than three pixels, which demonstrates a high level of automation, robustness and accuracy.

  1. Simulated full-waveform lidar compared to Riegl VZ-400 terrestrial laser scans

    Science.gov (United States)

    Kim, Angela M.; Olsen, Richard C.; Béland, Martin

    2016-05-01

    A 3-D Monte Carlo ray-tracing simulation of LiDAR propagation models the reflection, transmission and ab- sorption interactions of laser energy with materials in a simulated scene. In this presentation, a model scene consisting of a single Victorian Boxwood (Pittosporum undulatum) tree is generated by the high-fidelity tree voxel model VoxLAD using high-spatial resolution point cloud data from a Riegl VZ-400 terrestrial laser scanner. The VoxLAD model uses terrestrial LiDAR scanner data to determine Leaf Area Density (LAD) measurements for small volume voxels (20 cm sides) of a single tree canopy. VoxLAD is also used in a non-traditional fashion in this case to generate a voxel model of wood density. Information from the VoxLAD model is used within the LiDAR simulation to determine the probability of LiDAR energy interacting with materials at a given voxel location. The LiDAR simulation is defined to replicate the scanning arrangement of the Riegl VZ-400; the resulting simulated full-waveform LiDAR signals compare favorably to those obtained with the Riegl VZ-400 terrestrial laser scanner.

  2. Observation of clinical efficacy of pattern scan laser photocoagulation on diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Zhi-Hua Peng

    2013-08-01

    Full Text Available AIM: To evaluate the clinical efficacy of pattern scan laser photocoagulation(Pascalon proliferative diabetic retinopathy(PDR.METHODS: A total of 93 patients with retinopathy(186 eyeswere randomly divided into treatment group(96 eyes of 48 patientswho treated with panretinal photocoagulation(PRPusing Pascal at one time and control group(90 eyes of 45 patientswho treated with PRP using multi-wavelength krypton laser in 4-5 times. The visual acuity, FFA, OCT, visual field will be evaluated of each patient before and after the treatment.RESULTS: The visual acuity findings were stated as below: the overall effective rate of visual acuity in treatment group is 85.4% while it is 82.2% in control group. The overall effective rate in two groups has no significant difference. The retinal sensitivity has no significant decrease in the treatment group while which decreased significantly in the control group.CONCLUSION: The clinical efficacy of Pascal on treating the PDR is better than which of the regular argon laser. The field of vision has no significant narrowed after the Pascal treatment which can efficiently shorten the length of treatment and reduce the pain sensation.

  3. CO-REGISTRATION OF DSMs GENERATED BY UAV AND TERRESTRIAL LASER SCANNING SYSTEMS

    Directory of Open Access Journals (Sweden)

    R. A. Persad

    2016-06-01

    Full Text Available An approach for the co-registration of Digital Surface Models (DSMs derived from Unmanned Aerial Vehicles (UAVs and Terrestrial Laser Scanners (TLS is proposed. Specifically, a wavelet-based feature descriptor for matching surface keypoints on the 2.5D DSMs is developed. DSMs are useful in wide-scope of various applications such as 3D building modelling and reconstruction, cultural heritage, urban and environmental planning, aircraft navigation/path routing, accident and crime scene reconstruction, mining as well as, topographic map revision and change detection. For these listed applications, it is not uncommon that there will be a need for automatically aligning multi-temporal DSMs which may have been acquired from multiple sensors, with different specifications over a period of time, and may have various overlaps. Terrestrial laser scanners usually capture urban facades in an accurate manner; however this is not the case for building roof structures. On the other hand, vertical photography from UAVs can capture the roofs. Therefore, the automatic fusion of UAV and laser-scanning based DSMs is addressed here as it serves various geospatial applications.

  4. Local annealing of shape memory alloys using laser scanning and computer vision

    Science.gov (United States)

    Hafez, Moustapha; Bellouard, Yves; Sidler, Thomas C.; Clavel, Reymond; Salathe, Rene-Paul

    2000-11-01

    A complete set-up for local annealing of Shape Memory Alloys (SMA) is proposed. Such alloys, when plastically deformed at a given low temperature, have the ability to recover a previously memorized shape simply by heating up to a higher temperature. They find more and more applications in the fields of robotics and micro engineering. There is a tremendous advantage in using local annealing because this process can produce monolithic parts, which have different mechanical behavior at different location of the same body. Using this approach, it is possible to integrate all the functionality of a device within one piece of material. The set-up is based on a 2W-laser diode emitting at 805nm and a scanner head. The laser beam is coupled into an optical fiber of 60(mu) in diameter. The fiber output is focused on the SMA work-piece using a relay lens system with a 1:1 magnification, resulting in a spot diameter of 60(mu) . An imaging system is used to control the position of the laser spot on the sample. In order to displace the spot on the surface a tip/tilt laser scanner is used. The scanner is positioned in a pre-objective configuration and allows a scan field size of more than 10 x 10 mm2. A graphical user interface of the scan field allows the user to quickly set up marks and alter their placement and power density. This is achieved by computer controlling X and Y positions of the scanner as well as the laser diode power. A SMA micro-gripper with a surface area less than 1 mm2 and an opening of the jaws of 200(mu) has been realized using this set-up. It is electrically actuated and a controlled force of 16mN can be applied to hold and release small objects such as graded index micro-lenses at a cycle time of typically 1s.

  5. REGISTRATION OF LASER SCANNING POINT CLOUDS AND AERIAL IMAGES USING EITHER ARTIFICIAL OR NATURAL TIE FEATURES

    Directory of Open Access Journals (Sweden)

    P. Rönnholm

    2012-07-01

    Full Text Available Integration of laser scanning data and photographs is an excellent combination regarding both redundancy and complementary. Applications of integration vary from sensor and data calibration to advanced classification and scene understanding. In this research, only airborne laser scanning and aerial images are considered. Currently, the initial registration is solved using direct orientation sensors GPS and inertial measurements. However, the accuracy is not usually sufficient for reliable integration of data sets, and thus the initial registration needs to be improved. A registration of data from different sources requires searching and measuring of accurate tie features. Usually, points, lines or planes are preferred as tie features. Therefore, the majority of resent methods rely highly on artificial objects, such as buildings, targets or road paintings. However, in many areas no such objects are available. For example in forestry areas, it would be advantageous to be able to improve registration between laser data and images without making additional ground measurements. Therefore, there is a need to solve registration using only natural features, such as vegetation and ground surfaces. Using vegetation as tie features is challenging, because the shape and even location of vegetation can change because of wind, for example. The aim of this article was to compare registration accuracies derived by using either artificial or natural tie features. The test area included urban objects as well as trees and other vegetation. In this area, two registrations were performed, firstly, using mainly built objects and, secondly, using only vegetation and ground surface. The registrations were solved applying the interactive orientation method. As a result, using artificial tie features leaded to a successful registration in all directions of the coordinate system axes. In the case of using natural tie features, however, the detection of correct heights was

  6. The potential to characterize ecological data with terrestrial laser scanning in Harvard Forest, MA

    Science.gov (United States)

    Boucher, P.; Saenz, E.; Li, Z.

    2018-01-01

    Contemporary terrestrial laser scanning (TLS) is being used widely in forest ecology applications to examine ecosystem properties at increasing spatial and temporal scales. Harvard Forest (HF) in Petersham, MA, USA, is a long-term ecological research (LTER) site, a National Ecological Observatory Network (NEON) location and contains a 35 ha plot which is part of Smithsonian Institution's Forest Global Earth Observatory (ForestGEO). The combination of long-term field plots, eddy flux towers and the detailed past historical records has made HF very appealing for a variety of remote sensing studies. Terrestrial laser scanners, including three pioneering research instruments: the Echidna Validation Instrument, the Dual-Wavelength Echidna Lidar and the Compact Biomass Lidar, have already been used both independently and in conjunction with airborne laser scanning data and forest census data to characterize forest dynamics. TLS approaches include three-dimensional reconstructions of a plot over time, establishing the impact of ice storm damage on forest canopy structure, and characterizing eastern hemlock (Tsuga canadensis) canopy health affected by an invasive insect, the hemlock woolly adelgid (Adelges tsugae). Efforts such as those deployed at HF are demonstrating the power of TLS as a tool for monitoring ecological dynamics, identifying emerging forest health issues, measuring forest biomass and capturing ecological data relevant to other disciplines. This paper highlights various aspects of the ForestGEO plot that are important to current TLS work, the potential for exchange between forest ecology and TLS, and emphasizes the strength of combining TLS data with long-term ecological field data to create emerging opportunities for scientific study. PMID:29503723

  7. The potential to characterize ecological data with terrestrial laser scanning in Harvard Forest, MA.

    Science.gov (United States)

    Orwig, D A; Boucher, P; Paynter, I; Saenz, E; Li, Z; Schaaf, C

    2018-04-06

    Contemporary terrestrial laser scanning (TLS) is being used widely in forest ecology applications to examine ecosystem properties at increasing spatial and temporal scales. Harvard Forest (HF) in Petersham, MA, USA, is a long-term ecological research (LTER) site, a National Ecological Observatory Network (NEON) location and contains a 35 ha plot which is part of Smithsonian Institution's Forest Global Earth Observatory (ForestGEO). The combination of long-term field plots, eddy flux towers and the detailed past historical records has made HF very appealing for a variety of remote sensing studies. Terrestrial laser scanners, including three pioneering research instruments: the Echidna Validation Instrument, the Dual-Wavelength Echidna Lidar and the Compact Biomass Lidar, have already been used both independently and in conjunction with airborne laser scanning data and forest census data to characterize forest dynamics. TLS approaches include three-dimensional reconstructions of a plot over time, establishing the impact of ice storm damage on forest canopy structure, and characterizing eastern hemlock ( Tsuga canadensis ) canopy health affected by an invasive insect, the hemlock woolly adelgid ( Adelges tsugae ). Efforts such as those deployed at HF are demonstrating the power of TLS as a tool for monitoring ecological dynamics, identifying emerging forest health issues, measuring forest biomass and capturing ecological data relevant to other disciplines. This paper highlights various aspects of the ForestGEO plot that are important to current TLS work, the potential for exchange between forest ecology and TLS, and emphasizes the strength of combining TLS data with long-term ecological field data to create emerging opportunities for scientific study.

  8. Continuous-scanning laser Doppler vibrometry: Extensions to arbitrary areas, multi-frequency and 3D capture

    International Nuclear Information System (INIS)

    Weekes, B.; Ewins, D.; Acciavatti, F.

    2014-01-01

    To date, differing implementations of continuous scan laser Doppler vibrometry have been demonstrated by various academic institutions, but since the scan paths were defined using step or sine functions from function generators, the paths were typically limited to 1D line scans or 2D areas such as raster paths or Lissajous trajectories. The excitation was previously often limited to a single frequency due to the specific signal processing performed to convert the scan data into an ODS. In this paper, a configuration of continuous-scan laser Doppler vibrometry is demonstrated which permits scanning of arbitrary areas, with the benefit of allowing multi-frequency/broadband excitation. Various means of generating scan paths to inspect arbitrary areas are discussed and demonstrated. Further, full 3D vibration capture is demonstrated by the addition of a range-finding facility to the described configuration, and iteratively relocating a single scanning laser head. Here, the range-finding facility was provided by a Microsoft Kinect, an inexpensive piece of consumer electronics

  9. A walk by the river: three-dimensional reconstruction of surface sedimentology and topography using wearable laser scanning

    Science.gov (United States)

    Williams, R.; Lamy, M. L.; Stott, E.; Maniatis, G.

    2017-12-01

    In the last two decades, quantification of fluvial topography has been transformed by a number of geomatics technologies that have enabled the acquisition of data with unprecedented spatial resolution. Hyperscale surveys with spatial extents of <1 km2 have been widely demonstrated, by means of Terrestrial Laser Scanning (TLS) and Structure-from-Motion (SfM) photogrammetry. Recent advances in the development and integration of GNSS, IMU, lightweight laser scanning and SLAM technologies are now resulting in the emergence of wearable, mobile laser scanning systems that have the potential to increase data acquisition and processing rates by 1-2 orders of magnitude compared to TLS/SfM, and thus challenge the recent dominance of these two geomatics technologies. In this study we describe the methods and results of a comparison between a wearable laser scanning survey, using a Leica Pegasus Backpack, and a multi-station static TLS survey, using a Riegl VZ-1000 scanner. The evaluation is undertaken on a 600 m long reach of the braided River Feshie, Scotland, using data acquired in June 2017. Comparison between the DEMs produced from static and mobile laser scanning, across non-vegetated areas, revealed a Mean Error (ME) of -0.002 m and a Standard Deviation Error (SDE) of 0.109 m. Comparison to 100 independent check point resulted in a similar ME and SDE for static (ME = 0.061m; SDE = 0.030 m) and mobile (ME = 0.044 m; SDE = 0.029 m) laser scanning. Empirical relationships between sub-metre topographic variability and median sediment grain size (10-100 mm), across 14 grid-by-number samples, were similar and demonstrate that surface roughness from wearable laser scanning can be used to derive reach-scale maps of median grain size. These results demonstrate that wearable laser scanning generates hyperscale topographic models that are comparable in quality to more time-consuming multi-station TLS setups. Wearable laser scanning is likely to be commonly adopted for fluvial

  10. Safety, efficacy, predictability and stability of laser in situ keratomileusis (LASIK) with a 1000-Hz scanning spot excimer laser.

    Science.gov (United States)

    Khoramnia, Ramin; Salgado, Josefina P; Wuellner, Christian; Donitzky, Christof; Lohmann, Chris P; Winkler von Mohrenfels, Christoph

    2012-09-01

    To evaluate the safety, efficacy, predictability and stability of laser in situ keratomileusis (LASIK) with a 1000-Hz scanning spot excimer laser (Concept System 1000; WaveLight GmbH, Erlangen, Germany). LASIK was performed on twenty eyes with myopia or myopic astigmatism (mean spherical equivalent refraction: -3.97±1.72 dioptres (D); mean cylinder: -0.84±0.77 D) using a microkeratome for flap creation and the Concept System 1000 for photoablation. Patients were examined preoperatively as well as 1, 3 and 6 months after the treatment. Manifest sphere and cylinder, uncorrected (UCDVA) and best corrected (BCDVA) distance visual acuity, corneal topography and pachymetry were analysed. We observed no adverse events that might have been associated with the use of a repetition rate of 1000 Hz. All eyes maintained or had improved BCDVA at 6 months after treatment when compared to preoperative values. Six months after LASIK, UCDVA was 20/20 or better in 85% and 20/25 or better in 100% of the eyes. The spherical equivalent refraction was within ±0.50 D in 95% of the eyes at 6 months after surgery. The refraction stayed stable over time; 95% of the eyes changedLASIK with the prototype 1000-Hz excimer laser was safe, efficient and predictable. The postoperative refraction was stable over time. There were no specific clinical side-effects that might be associated with the use of such a high repetition rate. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

  11. Laser Scanning in Engineering Surveying: Methods of Measurement and Modeling of Structures

    Directory of Open Access Journals (Sweden)

    Lenda Grzegorz

    2016-06-01

    Full Text Available The study is devoted to the uses of laser scanning in the field of engineering surveying. It is currently one of the main trends of research which is developed at the Department of Engineering Surveying and Civil Engineering at the Faculty of Mining Surveying and Environmental Engineering of AGH University of Science and Technology in Krakow. They mainly relate to the issues associated with tower and shell structures, infrastructure of rail routes, or development of digital elevation models for a wide range of applications. These issues often require the use of a variety of scanning techniques (stationary, mobile, but the differences also regard the planning of measurement stations and methods of merging point clouds. Significant differences appear during the analysis of point clouds, especially when modeling objects. Analysis of the selected parameters is already possible basing on ad hoc measurements carried out on a point cloud. However, only the construction of three-dimensional models provides complete information about the shape of structures, allows to perform the analysis in any place and reduces the amount of the stored data. Some structures can be modeled in the form of simple axes, sections, or solids, for others it becomes necessary to create sophisticated models of surfaces, depicting local deformations. The examples selected for the study allow to assess the scope of measurement and office work for a variety of uses related to the issue set forth in the title of this study. Additionally, the latest, forward-looking technology was presented - laser scanning performed from Unmanned Aerial Vehicles (drones. Currently, it is basically in the prototype phase, but it might be expected to make a significant progress in numerous applications in the field of engineering surveying.

  12. High-speed automated NDT device for niobium plate using scanning laser acoustic microscopy

    International Nuclear Information System (INIS)

    Oravecz, M.G.; Yu, B.Y.; Riney, K.; Kessler, L.W.; Padamsee, H.

    1988-01-01

    This paper presents a nondestructive testing (NDT) device which rapidly and automatically identifies defects throughout the volume of a 23.4 cm x 23.4 cm x 0.3 cm, pure niobium plate using Scanning Laser Acoustic Microscope (SLAM), high-resolution, 60 MHz, ultrasonic images. A principle advantage of the SLAM technique is that it combines a video scan rate with a high scan density (130 lines/mm at 60 MHz). To automate the inspection system they integrated under computer control the following: the SLAM RS-170/330 video output, a computerized XY plate scanner, a real-time video digitizer/integrator, a computer algorithm for defect detection, a digital mass storage device, and a hardcopy output device. The key element was development of an efficient, reliable defect detection algorithm using a variance filter with a locally determined threshold. This algorithm is responsible for recognizing valid flaws in the midst of random texture. This texture was seen throughout the acoustic images and was caused by the niobium microstructure. The images, as analyzed, contained 128 x 120 pixels with 64 grey levels per pixel. This system allows economical inspection of the large quantities (eg. 100 tons) of material needed for future particle accelerators based on microwave superconductivity. Rapid nondestructive inspection of pure niobium sheet is required because current accelerator performance is largely limited by the quality of commercially available material. Previous work documented critical flaws that are detectable by SLAM techniques. 15 references, 9 figures

  13. Towards simultaneous Talbot bands based optical coherence tomography and scanning laser ophthalmoscopy imaging.

    Science.gov (United States)

    Marques, Manuel J; Bradu, Adrian; Podoleanu, Adrian Gh

    2014-05-01

    We report a Talbot bands-based optical coherence tomography (OCT) system capable of producing longitudinal B-scan OCT images and en-face scanning laser ophthalmoscopy (SLO) images of the human retina in-vivo. The OCT channel employs a broadband optical source and a spectrometer. A gap is created between the sample and reference beams while on their way towards the spectrometer's dispersive element to create Talbot bands. The spatial separation of the two beams facilitates collection by an SLO channel of optical power originating exclusively from the retina, deprived from any contribution from the reference beam. Three different modes of operation are presented, constrained by the minimum integration time of the camera used in the spectrometer and by the galvo-scanners' scanning rate: (i) a simultaneous acquisition mode over the two channels, useful for small size imaging, that conserves the pixel-to-pixel correspondence between them; (ii) a hybrid sequential mode, where the system switches itself between the two regimes and (iii) a sequential "on-demand" mode, where the system can be used in either OCT or SLO regimes for as long as required. The two sequential modes present varying degrees of trade-off between pixel-to-pixel correspondence and independent full control of parameters within each channel. Images of the optic nerve and fovea regions obtained in the simultaneous (i) and in the hybrid sequential mode (ii) are presented.

  14. The effect of short ground vegetation on terrestrial laser scans at a local scale

    Science.gov (United States)

    Fan, Lei; Powrie, William; Smethurst, Joel; Atkinson, Peter M.; Einstein, Herbert

    2014-09-01

    Terrestrial laser scanning (TLS) can record a large amount of accurate topographical information with a high spatial accuracy over a relatively short period of time. These features suggest it is a useful tool for topographical survey and surface deformation detection. However, the use of TLS to survey a terrain surface is still challenging in the presence of dense ground vegetation. The bare ground surface may not be illuminated due to signal occlusion caused by vegetation. This paper investigates vegetation-induced elevation error in TLS surveys at a local scale and its spatial pattern. An open, relatively flat area vegetated with dense grass was surveyed repeatedly under several scan conditions. A total station was used to establish an accurate representation of the bare ground surface. Local-highest-point and local-lowest-point filters were applied to the point clouds acquired for deriving vegetation height and vegetation-induced elevation error, respectively. The effects of various factors (for example, vegetation height, edge effects, incidence angle, scan resolution and location) on the error caused by vegetation are discussed. The results are of use in the planning and interpretation of TLS surveys of vegetated areas.

  15. Cosmic polarimetry in magnetoactive plasmas

    CERN Document Server

    Giovannini, Massimo

    2009-01-01

    Polarimetry of the Cosmic Microwave Background (CMB) represents one of the possible diagnostics aimed at testing large-scale magnetism at the epoch of the photon decoupling. The propagation of electromagnetic disturbances in a magnetized plasma leads naturally to a B-mode polarization whose angular power spectrum is hereby computed both analytically and numerically. Combined analyses of all the publicly available data on the B-mode polarization are presented, for the first time, in the light of the magnetized $\\Lambda$CDM scenario. Novel constraints on pre-equality magnetism are also derived in view of the current and expected sensitivities to the B-mode polarization.

  16. 3D laser scanning techniques applying to tunnel documentation and geological mapping at Aespoe hard rock laboratory, Sweden

    International Nuclear Information System (INIS)

    Feng, Q.; Wang, G.; Roeshoff, K.

    2008-01-01

    3D terrestrial laser scanning is nowadays one of the most attractive methods to applying for 3D mapping and documentation of rock faces and tunnels, and shows the most potential to improve the data quality and provide some good solutions in rock engineering projects. In this paper, the state-of-the-art methods are described for different possibility to tunnel documentation and geological mapping based on 3D laser scanning data. Some results are presented from the case study performed at the Hard Rock Laboratory, Aespoe run by SKB, Swedish Nuclear Fuel and Waste Management Co. Comparing to traditional methods, 3D laser scanning techniques can not only provide us with a rapid and 3D digital way for tunnel documentation, but also create a potential chance to achieve high quality data, which might be beneficial to different rock engineering project procedures, including field data acquisition, data processing, data retrieving and management, and also modeling and design. (authors)

  17. Impact of multiple sub-melt laser scans on the activation and diffusion of shallow Boron junctions

    DEFF Research Database (Denmark)

    Rosseel, E.; Vandervorst, W.; Clarysse, T.

    2008-01-01

    , careful process optimization is required. While macroscopic variations can easily be addressed using the proper spatial power compensation it is more difficult to completely eliminate the micro scale non-uniformity which is intimately linked to the laser beam profile, the amount of overlaps and the scan...... pitch. In this work, we will present micro scale sheet resistance uniformity measurements for shallow 0.5 keV B junctions and zoom in on the underlying effect of multiple subsequent laser scans. A variety of characterization techniques are used to extract the relevant junction parameters and the role...... of different implantation and anneal parameters will be explored. It turns out that the observed sheet resistance decrease with increasing number of laser scans is caused on one hand by a temperature dependent increase of the activation level, and on the other hand, by a non-negligible temperature...

  18. Forest Inventory with Terrestrial LiDAR: A Comparison of Static and Hand-Held Mobile Laser Scanning

    Directory of Open Access Journals (Sweden)

    Sébastien Bauwens

    2016-06-01

    Full Text Available The application of static terrestrial laser scanning (TLS in forest inventories is becoming more effective. Nevertheless, the occlusion effect is still limiting the processing efficiency to extract forest attributes. The use of a mobile laser scanner (MLS would reduce this occlusion. In this study, we assessed and compared a hand-held mobile laser scanner (HMLS with two TLS approaches (single scan: SS, and multi scan: MS for the estimation of several forest parameters in a wide range of forest types and structures. We found that SS is competitive to extract the ground surface of forest plots, while MS gives the best result to describe the upper part of the canopy. The whole cross-section at 1.3 m height is scanned for 91% of the trees (DBH > 10 cm with the HMLS leading to the best results for DBH estimates (bias of −0.08 cm and RMSE of 1.11 cm, compared to no fully-scanned trees for SS and 42% fully-scanned trees for MS. Irregularities, such as bark roughness and non-circular cross-section may explain the negative bias encountered for all of the scanning approaches. The success of using MLS in forests will allow for 3D structure acquisition on a larger scale and in a time-efficient manner.

  19. Radar Polarimetry and Interferometry (La polarimetrie et l'interferometrie radar) (CD-ROM)

    National Research Council Canada - National Science Library

    Keydel, W; Boerner, W. M; Pottier, E; Lee, J. S; Ferro-Famil, L; Hellmann, M; Cloude, S. R

    2005-01-01

    ...: Scientists and engineers already engaged in the fields of radar surveillance, reconnaissance and scattering measurements, for instance, generally gain their specialist knowledge in both polarimetry...

  20. EIC Electron Beam Polarimetry Workshop Summary

    International Nuclear Information System (INIS)

    Lorenzon, W.

    2008-01-01

    A summary of the Precision Electron Beam Polarimetry Workshop for a future Electron Ion Collider (EIC) is presented. The workshop was hosted by the University of Michigan Physics Department in Ann Arbor on August 23-24, 2007 with the goal to explore and study the electron beam polarimetry issues associated with the EIC to achieve sub-1% precision in polarization determination. Ideas are being presented that were exchanged among experts in electron polarimetry and source and accelerator design to examine existing and novel electron beam polarization measurement schemes

  1. Evaluation of positional plagiocephaly: Conventional anthropometric measurement versus laser scanning method.

    Science.gov (United States)

    Nahles, Susanne; Klein, Martin; Yacoub, Anke; Neyer, Julia

    2018-01-01

    The incidence of plagiocephaly has increased in the 25 years since the "Back to Sleep" campaign in 1991 to prevent sudden infant death. Plagiocephaly is not considered to be a pathological condition. It is more of an esthetic impairment and could have potentially negative psychological or psychosocial consequences; therefore, treatment is recommended. The aim of this study is to compare conventional anthropometry and laser scanning - two different measurement methods - as diagnostic instruments for plagiocephaly. The present study also tests the measurement time of both methods and whether one method is easier on the patient than the other. A total of 44 children (21 girls, 23 boys) with a mean age of 8.8 months were involved in the present study. Of all patients, the following parameters were routinely evaluated using a standard protocol with the conventional anthropometric method and the scan method: head circumference, head length, head width, head diagonals, and distances ex-t. Furthermore, the time required to obtain measurements and the behavior of the children during measurement were documented. For statistical analysis, a t-test and a Wilcoxon test were used to analyze differences between the two methods. The results for head circumference showed a mean of 441.5 mm for the anthropometric measurements and 441.6 mm for the scan method, with no significant difference between the two methods. A significant difference was found regarding the head width, head length, diagonals, and distance ex-t. The measurement process using the scan method needed a mean of 579.6 s in contrast to the manual anthropometric method, which required a mean time of 180.5 s. In comparison with the conventional anthropometric method, measurements made with a 3D laser scanner yield inconsistent results. Moreover, the current state of technology of 3D cephalometry has no advantages compared with the conventional anthropometric method. Disadvantages worth mentioning appear to be the

  2. The reality of virtual anthropology: Comparing digitizer and laser scan data collection methods for the quantitative assessment of the cranium.

    Science.gov (United States)

    Algee-Hewitt, Bridget F B; Wheat, Amber D

    2016-05-01

    The use of geometric morphometry to study cranial variation has steadily grown in appeal over the past decade in biological anthropology. Publication trends suggest that the most popular methods for three-dimensional data acquisition involve landmark-based coordinate data collection using a digitizer. Newer laser scan approaches are seeing increasing use, owing to the benefits that densely sampled data offer. While both of these methods have their utility, research that investigates their compatibility is lacking. The purpose of this project is to compare, quantitatively, craniometrics collected with a digitizer against data extracted from laser scans using the same individuals and laboratory conditions. Three-dimensional (x,y,z) coordinates and traditional inter-landmark distances (ILDs) were obtained with a Microscribe digitizer and 360° color models produced from NextEngine laser scans for 38 adult crania representing five cemeteries from the ADBOU skeletal collection in Denmark. Variance-based tests were performed to evaluate the disagreement between data collected with a digitizer and from laser scan models. Consideration was given to differences among landmarks by type, between ILDs calculated from landmark coordinates, and in morphology for the cemetery populations. Further, the reliability of laser scan data collection was assessed by intra-observer error tests. Researchers should be aware of the potential error associated with the use of Types II and III landmarks and the limitations on reliability imposed by object-to-scanner placement. This project reveals how laser scans can provide a valuable digital archive of cranial material that can be reasonably exploited for the "virtual" collection of coordinates and the calculation of ILDs. © 2015 Wiley Periodicals, Inc.

  3. Photonic crystal fibre enables short-wavelength two-photon laser scanning fluorescence microscopy with fura-2

    International Nuclear Information System (INIS)

    McConnell, Gail; Riis, Erling

    2004-01-01

    We report on a novel and compact reliable laser source capable of short-wavelength two-photon laser scanning fluorescence microscopy based on soliton self-frequency shift effects in photonic crystal fibre. We demonstrate the function of the system by performing two-photon microscopy of smooth muscle cells and cardiac myocytes from the rat pulmonary vein and Chinese hamster ovary cells loaded with the fluorescent calcium indicator fura-2/AM

  4. A simple but precise method for quantitative measurement of the quality of the laser focus in a scanning optical microscope.

    Science.gov (United States)

    Trägårdh, J; Macrae, K; Travis, C; Amor, R; Norris, G; Wilson, S H; Oppo, G-L; McConnell, G

    2015-07-01

    We report a method for characterizing the focussing laser beam exiting the objective in a laser scanning microscope. This method provides the size of the optical focus, the divergence of the beam, the ellipticity and the astigmatism. We use a microscopic-scale knife edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide, and a light-collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, a beam profile in the form of an error function can be obtained and by repeating this with the knife edge at different axial positions relative to the beam waist, the divergence and astigmatism of the postobjective laser beam can be obtained. The measured divergence can be used to quantify how much of the full numerical aperture of the lens is used in practice. We present data of the beam radius, beam divergence, ellipticity and astigmatism obtained with low (0.15, 0.7) and high (1.3) numerical aperture lenses and lasers commonly used in confocal and multiphoton laser scanning microscopy. Our knife-edge method has several advantages over alternative knife-edge methods used in microscopy including that the knife edge is easy to prepare, that the beam can be characterized also directly under a cover slip, as necessary to reduce spherical aberrations for objectives designed to be used with a cover slip, and it is suitable for use with commercial laser scanning microscopes where access to the laser beam can be limited. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  5. Application of terrestrial laser scanning to the development and updating of the base map

    Directory of Open Access Journals (Sweden)

    Klapa Przemysław

    2017-06-01

    Full Text Available The base map provides basic information about land to individuals, companies, developers, design engineers, organizations, and government agencies. Its contents include spatial location data for control network points, buildings, land lots, infrastructure facilities, and topographic features. As the primary map of the country, it must be developed in accordance with specific laws and regulations and be continuously updated. The base map is a data source used for the development and updating of derivative maps and other large scale cartographic materials such as thematic or topographic maps. Thanks to the advancement of science and technology, the quality of land surveys carried out by means of terrestrial laser scanning (TLS matches that of traditional surveying methods in many respects.

  6. Investigation of phosphatidylcholine enhancing FITC-insulin across buccal mucosa by confocal laser scanning microscopy

    Science.gov (United States)

    Tian, Weiqun; Su, Li; Zeng, Shaoqun; Luo, Qingming; Gao, Qiuhua; Xu, Huibi

    2002-04-01

    The aim was to characterize the transport of fluorescein isothiocyanate (FITC)-labeled dextran and insulin with different resoluble compounds for peptides and proteins through buccal mucosa. The penetration rate of insulin molecules through porcine buccal mucosa (a nonkeratinized epithelium, comparable to human buccal mucosa) was investigated by measuring transbuccal fluxes and by analyzing the distribution of the fluorescent probe in the rabbit buccal mucosa epithelium, using confocal laser scanning microscopy for visualizing permeation pathways. The confocal images of the distribution pattern of FITC-dextran and FITC-insulin showed that the paracellular route is the major pathway of FITC-dextran through buccal mucosa epithelium, the intra-cellular route is the major pathway of FITC-insulin through buccal mucosa epithelium. The permeation rate can be increased by co-administration of soybean phosphatidylcholine (SPC).

  7. Optimal Information Extraction of Laser Scanning Dataset by Scale-Adaptive Reduction

    Science.gov (United States)

    Zang, Y.; Yang, B.

    2018-04-01

    3D laser technology is widely used to collocate the surface information of object. For various applications, we need to extract a good perceptual quality point cloud from the scanned points. To solve the problem, most of existing methods extract important points based on a fixed scale. However, geometric features of 3D object come from various geometric scales. We propose a multi-scale construction method based on radial basis function. For each scale, important points are extracted from the point cloud based on their importance. We apply a perception metric Just-Noticeable-Difference to measure degradation of each geometric scale. Finally, scale-adaptive optimal information extraction is realized. Experiments are undertaken to evaluate the effective of the proposed method, suggesting a reliable solution for optimal information extraction of object.

  8. BUILDING FACADE DOCUMENTATION USING LASER SCANNING AND PHOTOGRAMMETRY AND DATA IMPLEMENTATION INTO BIM

    Directory of Open Access Journals (Sweden)

    M. Faltýnová

    2016-06-01

    Full Text Available A project started last year called MORE-CONNECT, which focuses on the renovation of buildings (especially building facades using prefabricated elements. The aim of this project is to create a competitive solution consisting of a technology and processes which enable fast, cost-effective renovation with minimal difficulties to inhabitants. Significant cost savings in renovation costs lies in the usage of prefabricated elements and the reduction of construction works on site. The precision of the prefabricated element depends on the precision of the construction, project and building documentation. This article offers an overview of the possible methods for building documentation and spatial data transfer into BIM (Building Information Modelling software. The description of methods focuses on laser scanning and photogrammetry (including RPAS based, its advantages, disadvantages and limitations according to the documented building, level of renovation, situation on site etc. The next part involves spatial data transfer into BIM software. A proposed solution is tested in a case study.

  9. Concrete Crack Measurement and Analysis Based on Terrestrial Laser Scanning Technology

    Directory of Open Access Journals (Sweden)

    Xiangyang Xu

    2015-03-01

    Full Text Available Terrestrial laser scanning (TLS has become one of the potential technologies for an object three-dimensional (3D information acquisition. The using vibration analysis for early detection of cracks has gained popularity over the years and in the last decade substantial progress has been made in that direction. However, the crack detection using TLS is also a good method. In the experimental part of this study, the effect of crack width and location on modal properties of the beam was investigated. The recent paper provides a method for automatic concrete cracks detection from the data that was obtained by TLS. The method of cracks detection is achieved by six steps. The objective of this study is to analyze the crack of concrete beams both experimentally and using MATLAB analysis. Besides this, information about the width, location and percentage of cracks in cracked concrete beams can be obtained using this technique.

  10. A hand-held 3D laser scanning with global positioning system of subvoxel precision

    International Nuclear Information System (INIS)

    Arias, Nestor; Meneses, Nestor; Meneses, Jaime; Gharbi, Tijani

    2011-01-01

    In this paper we propose a hand-held 3D laser scanner composed of an optical head device to extract 3D local surface information and a stereo vision system with subvoxel precision to measure the position and orientation of the 3D optical head. The optical head is manually scanned over the surface object by the operator. The orientation and position of the 3D optical head is determined by a phase-sensitive method using a 2D regular intensity pattern. This phase reference pattern is rigidly fixed to the optical head and allows their 3D location with subvoxel precision in the observation field of the stereo vision system. The 3D resolution achieved by the stereo vision system is about 33 microns at 1.8 m with an observation field of 60cm x 60cm.

  11. Recognition and Reconstruction of Zebra Crossings on Roads from Mobile Laser Scanning Data

    Directory of Open Access Journals (Sweden)

    Lin Li

    2016-07-01

    Full Text Available Zebra crossings provide guidance and warning to pedestrians and drivers, thereby playing an important role in traffic safety management. Most previous studies have focused on detecting zebra stripes but have not provided full information about the areas, which is critical to both driver assistance systems and guide systems for blind individuals. This paper presents a stepwise procedure for recognizing and reconstructing zebra crossings using mobile laser scanning data. First, we propose adaptive thresholding based on road surface partitioning to reduce the impact of intensity unevenness and improve the accuracy of road marking extraction. Then, dispersion degree filtering is used to reduce the noise. Finally, zebra stripes are recognized according to the rectangular feature and fixed size, which is followed by area reconstruction according to arrangement patterns. We test our method on three datasets captured by an Optech Lynx mobile mapping system. The total recognition rate of 90.91% demonstrates the effectiveness of the method.

  12. Adaptive optics scanning laser ophthalmoscopy in fundus imaging, a review and update

    Directory of Open Access Journals (Sweden)

    Bing Zhang

    2017-11-01

    Full Text Available Adaptive optics scanning laser ophthalmoscopy (AO-SLO has been a promising technique in funds imaging with growing popularity. This review firstly gives a brief history of adaptive optics (AO and AO-SLO. Then it compares AO-SLO with conventional imaging methods (fundus fluorescein angiography, fundus autofluorescence, indocyanine green angiography and optical coherence tomography and other AO techniques (adaptive optics flood-illumination ophthalmoscopy and adaptive optics optical coherence tomography. Furthermore, an update of current research situation in AO-SLO is made based on different fundus structures as photoreceptors (cones and rods, fundus vessels, retinal pigment epithelium layer, retinal nerve fiber layer, ganglion cell layer and lamina cribrosa. Finally, this review indicates possible research directions of AO-SLO in future.

  13. In vivo integrated photoacoustic ophthalmoscopy, optical coherence tomography, and scanning laser ophthalmoscopy for retinal imaging

    Science.gov (United States)

    Song, Wei; Zhang, Rui; Zhang, Hao F.; Wei, Qing; Cao, Wenwu

    2012-12-01

    The physiological and pathological properties of retina are closely associated with various optical contrasts. Hence, integrating different ophthalmic imaging technologies is more beneficial in both fundamental investigation and clinical diagnosis of several blinding diseases. Recently, photoacoustic ophthalmoscopy (PAOM) was developed for in vivo retinal imaging in small animals, which demonstrated the capability of imaging retinal vascular networks and retinal pigment epithelium (RPE) at high sensitivity. We combined PAOM with traditional imaging modalities, such as fluorescein angiography (FA), spectral-domain optical coherence tomography (SD-OCT), and auto-fluorescence scanning laser ophthalmoscopy (AF-SLO), for imaging rats and mice. The multimodal imaging system provided more comprehensive evaluation of the retina based on the complementary imaging contrast mechanisms. The high-quality retinal images show that the integrated ophthalmic imaging system has great potential in the investigation of blinding disorders.

  14. Integrated fringe projection 3D scanning system for large-scale metrology based on laser tracker

    Science.gov (United States)

    Du, Hui; Chen, Xiaobo; Zhou, Dan; Guo, Gen; Xi, Juntong

    2017-10-01

    Large scale components exist widely in advance manufacturing industry,3D profilometry plays a pivotal role for the quality control. This paper proposes a flexible, robust large-scale 3D scanning system by integrating a robot with a binocular structured light scanner and a laser tracker. The measurement principle and system construction of the integrated system are introduced. And a mathematical model is established for the global data fusion. Subsequently, a flexible and robust method and mechanism is introduced for the establishment of the end coordination system. Based on this method, a virtual robot noumenon is constructed for hand-eye calibration. And then the transformation matrix between end coordination system and world coordination system is solved. Validation experiment is implemented for verifying the proposed algorithms. Firstly, hand-eye transformation matrix is solved. Then a car body rear is measured for 16 times for the global data fusion algorithm verification. And the 3D shape of the rear is reconstructed successfully.

  15. SINGLE TREE DETECTION FROM AIRBORNE LASER SCANNING DATA USING A MARKED POINT PROCESS BASED METHOD

    Directory of Open Access Journals (Sweden)

    J. Zhang

    2013-05-01

    Full Text Available Tree detection and reconstruction is of great interest in large-scale city modelling. In this paper, we present a marked point process model to detect single trees from airborne laser scanning (ALS data. We consider single trees in ALS recovered canopy height model (CHM as a realization of point process of circles. Unlike traditional marked point process, we sample the model in a constraint configuration space by making use of image process techniques. A Gibbs energy is defined on the model, containing a data term which judge the fitness of the model with respect to the data, and prior term which incorporate the prior knowledge of object layouts. We search the optimal configuration through a steepest gradient descent algorithm. The presented hybrid framework was test on three forest plots and experiments show the effectiveness of the proposed method.

  16. Confocal laser scanning microscopy detection of chlorophylls and carotenoids in chloroplasts and chromoplasts of tomato fruit.

    Science.gov (United States)

    D'Andrea, Lucio; Amenós, Montse; Rodríguez-Concepción, Manuel

    2014-01-01

    Plant cells are unique among eukaryotic cells because of the presence of plastids, including chloroplasts and chromoplasts. Chloroplasts are found in green tissues and harbor the photosynthetic machinery (including chlorophyll molecules), while chromoplasts are present in non-photosynthetic tissues and accumulate large amounts of carotenoids. During tomato fruit development, chloroplasts are converted into chromoplasts that accumulate high levels of lycopene, a linear carotenoid responsible for the characteristic red color of ripe fruit. Here, we describe a simple and fast method to detect both types of fully differentiated plastids (chloroplasts and chromoplasts), as well as intermediate stages, in fresh tomato fruits. The method is based on the differential autofluorescence of chlorophylls and carotenoids (lycopene) detected by Confocal Laser Scanning Microscopy.

  17. Analysis of the melanin distribution in different ethnic groups by in vivo laser scanning microscopy

    International Nuclear Information System (INIS)

    Antoniou, C; Lademann, J; Richter, H; Patzelt, A; Sterry, W; Astner, S; Zastrow, L; Koch, S

    2009-01-01

    The aim of this study was to determine whether Laser scanning confocal microscopy (LSM) is able to visualize differences in melanin content and distribution in different Skin Phototypes. The investigations were carried out on six healthy volunteers with Skin Phototypes II, IV, and VI. Representative skin samples of Skin Phototypes II, V, and VI were obtained for histological analysis from remaining tissue of skin grafts and were used for LSM-pathologic correlation. LSM evaluation showed significant differences in melanin distribution in Skin Phototypes II, IV, and VI, respectively. Based on the differences in overall reflectivity and image brightness, a visual evaluation scheme showed increasing brightness of the basal and suprabasal layers with increasing Skin Phototypes. The findings correlated well with histological analysis. The results demonstrate that LSM may serve as a promising adjunctive tool for real time assessment of melanin content and distribution in human skin, with numerous clinical applications and therapeutic and preventive implications

  18. OPTIMAL INFORMATION EXTRACTION OF LASER SCANNING DATASET BY SCALE-ADAPTIVE REDUCTION

    Directory of Open Access Journals (Sweden)

    Y. Zang

    2018-04-01

    Full Text Available 3D laser technology is widely used to collocate the surface information of object. For various applications, we need to extract a good perceptual quality point cloud from the scanned points. To solve the problem, most of existing methods extract important points based on a fixed scale. However, geometric features of 3D object come from various geometric scales. We propose a multi-scale construction method based on radial basis function. For each scale, important points are extracted from the point cloud based on their importance. We apply a perception metric Just-Noticeable-Difference to measure degradation of each geometric scale. Finally, scale-adaptive optimal information extraction is realized. Experiments are undertaken to evaluate the effective of the proposed method, suggesting a reliable solution for optimal information extraction of object.

  19. A Graph Cut Approach to Artery/Vein Classification in Ultra-Widefield Scanning Laser Ophthalmoscopy.

    Science.gov (United States)

    Pellegrini, Enrico; Robertson, Gavin; MacGillivray, Tom; van Hemert, Jano; Houston, Graeme; Trucco, Emanuele

    2018-02-01

    The classification of blood vessels into arterioles and venules is a fundamental step in the automatic investigation of retinal biomarkers for systemic diseases. In this paper, we present a novel technique for vessel classification on ultra-wide-field-of-view images of the retinal fundus acquired with a scanning laser ophthalmoscope. To the best of our knowledge, this is the first time that a fully automated artery/vein classification technique for this type of retinal imaging with no manual intervention has been presented. The proposed method exploits hand-crafted features based on local vessel intensity and vascular morphology to formulate a graph representation from which a globally optimal separation between the arterial and venular networks is computed by graph cut approach. The technique was tested on three different data sets (one publicly available and two local) and achieved an average classification accuracy of 0.883 in the largest data set.

  20. Comparasion of Optic Nerve Head with Stereophotometric and Scanning Laser Ophthalmoscopic Imaging

    Directory of Open Access Journals (Sweden)

    Serek Tekin

    2016-01-01

    Full Text Available Aim: To compare theevaluation results of two experienced clinicians about examination of optic discs in glaucoma patients and healthy inidividuals by stereophotometry and scanning laser ophthalmoscopy. Material and Method: We studied 116 individuals (217 eyes who were divided as normal, glaucoma and suspected glaucoma in numbers of 54, 42 and 20 respectively. Stereophotometric photographs of optic disc were examined with fundus camera (Zeiss, FF 450 plus. Optic disc was also evaluated with HRT-3 in the same visit. Two experienced clinicians evaluated the cup/disc ratios and whether the optic discs were glaucomatous or not. Evaluation results were analysed and compared with HRT-3 examinations. Results:There were no significant age and gende rdifferences between the groups(p>0.05.Stereophotographic C/D ratio correlations between the clinicians were 0.79 (p

  1. Novel Infiltration Diagnostics based on Laser-line Scanning and Infrared Temperature Field Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xinwei [Iowa State Univ., Ames, IA (United States)

    2017-12-08

    This project targets the building energy efficiency problems induced by building infiltration/leaks. The current infiltration inspection techniques often require extensive visual inspection and/or whole building pressure test. These current techniques cannot meet more than three of the below five criteria of ideal infiltration diagnostics: 1. location and extent diagnostics, 2. building-level application, 3. least surface preparation, 4. weather-proof, and 5. non-disruption to building occupants. These techniques are either too expensive or time consuming, and often lack accuracy and repeatability. They are hardly applicable to facades/facades section. The goal of the project was to develop a novel infiltration diagnostics technology based on laser line-scanning and simultaneous infrared temperature imaging. A laboratory scale experimental setup was designed to mimic a model house of well-defined pressure difference below or above the outside pressure. Algorithms and Matlab-based programs had been developed for recognition of the hole location in infrared images. Our experiment based on laser wavelengths of 450 and 1550 nm and laser beam diameters of 4-25 mm showed that the location of the holes could be identified using laser heating; the diagnostic approach however could not readily distinguish between infiltration and non-infiltration points. To significantly improve the scanning throughput and recognition accuracy, a second approach was explored, developed, and extensively tested. It incorporates a liquid spray on the surface to induce extra phase change cooling effect. In this spray method, we termed it as PECIT (Phase-change Enhanced Cooling Infrared Thermography), phase-change enhanced cooling was used, which significantly amplifies the effect of air flow (infiltration and exfiltration). This heat transfer method worked extremely well to identify infiltration and exfiltration locations with high accuracy and increased throughput. The PECIT technique was

  2. Multi-temporal terrestrial laser scanning for identifying rockslide modifications: potentialities and problems

    Science.gov (United States)

    Castagnetti, Cristina; Bertacchini, Eleonora; Capra, Alessandro; Rivola, Riccardo

    2013-04-01

    The heart of this research is to provide an efficient methodology for a reliable acquisition and interpretation of Terrestrial Laser Scanner (TLS) data in the application field of landslide monitoring. In particular, rockslides, which are characterized by vertical walls of rock and by a complex morphology, are of great concern in the study. In these cases the airborne laser scanning is not able to provide useful and reliable description and the terrestrial laser scanning might be the only possible choice to obtain a good and reliable description of the geomorphology or to identify the changes occurred over time. The last purpose is still a challenging task when long distances are involved because the accurate and punctual identification of displacements is not possible due to the laser beam divergence. The final purpose of the research is a proposal of a methodology which is based on TLS technology for identifying displacements and extracting geomorphological changes. The approach is clearly based on a multi-temporal analysis which is computed on several repetitions of TLS surveys performed on the area of interest. To achieve best results and optimize the processing strategy, different methods about point clouds alignment have been tested together with algorithms both for filtering and post-processing. The case study is the Collagna Landslide that is located in the North Appennines (Reggio Emilia, Italy) on the right flank of Biola torrent. The large scale composite landslide area is made both by a wide rock slide sector and a more limited earth slide sector that, after high precipitation rates, disrupted the National Road 63 in December 2008. An integrated monitoring system is installed since 2009 and comprises both point-based technologies such as extensometers, total station and global positioning system, and also area-based technologies such as airborne laser scanner, long-range TLS and ground-based radar. This choice allows to couple the advantages of both

  3. Geodetic Imaging for Rapid Assessment of Earthquakes: Airborne Laser Scanning (ALS)

    Science.gov (United States)

    Carter, W. E.; Shrestha, R. L.; Glennie, C. L.; Sartori, M.; Fernandez-Diaz, J.; National CenterAirborne Laser Mapping Operational Center

    2010-12-01

    To the residents of an area struck by a strong earthquake quantitative information on damage to the infrastructure, and its attendant impact on relief and recovery efforts, is urgent and of primary concern. To earth scientists a strong earthquake offers an opportunity to learn more about earthquake mechanisms, and to compare their models with the real world, in hopes of one day being able to accurately predict the precise locations, magnitudes, and times of large (and potentially disastrous) earthquakes. Airborne laser scanning (also referred to as airborne LiDAR or Airborne Laser Swath Mapping) is particularly well suited for rapid assessment of earthquakes, both for immediately estimating the damage to infrastructure and for providing information for the scientific study of earthquakes. ALS observations collected at low altitude (500—1000m) from a relatively slow (70—100m/sec) aircraft can provide dense (5—15 points/m2) sets of surface features (buildings, vegetation, ground), extending over hundreds of square kilometers with turn around times of several hours to a few days. The actual response time to any given event depends on several factors, including such bureaucratic issues as approval of funds, export license formalities, and clearance to fly over the area to be mapped, and operational factors such as the deployment of the aircraft and ground teams may also take a number of days for remote locations. Of course the need for immediate mapping of earthquake damage generally is not as urgent in remote regions with less infrastructure and few inhabitants. During August 16-19, 2010 the National Center for Airborne Laser Mapping (NCALM) mapped the area affected by the magnitude 7.2 El Mayor-Cucapah Earthquake (Northern Baja California Earthquake), which occurred on April 4, 2010, and was felt throughout southern California, Arizona, Nevada, and Baja California North, Mexico. From initial ground observations the fault rupture appeared to extend 75 km

  4. 3D laser scanning in plant and pipeline engineering; 3D-Laserscanning im Anlagen- und Rohrleitungsbau

    Energy Technology Data Exchange (ETDEWEB)

    Weber, T. [Kaeser und Reiner, Ingenieurbuero fuer Vermessung und Geoinformation, Fellbach (Germany)

    2006-05-15

    3D laser scanning has been in use for a number of years now in the fields of surveying, building and factory planning. Laser scanning can, however, provide a highly supportive and helpful tool for the plant and piping designer, too. The benefits of this technology are relevant wherever the geometry of existing systems and subsystems needs to be registered and recorded. This may be the case in planning changes (basic and detail engineering), collision checks, documentation, plant relocations and visual?display projects. (orig.)

  5. Equivalente esférico e valores da espessura da camada de fibras nervosas obtidas com o GDX TM Scanning Laser System® Spherical equivalent and nerve fiber layer thickness assessed with GDX TM Scanning Laser System®

    Directory of Open Access Journals (Sweden)

    Lênio Souza Alvarenga

    1999-12-01

    Full Text Available Objetivo: Estudar a influência do equivalente esférico nos valores obtidos pelo GDX TM Scanning Laser System®. Métodos: Foram avaliados 41 olhos de 41 voluntários sem doenças oculares e com campo visual sem alterações. Foi realizada a polarimetria de varredura a laser com o GDX TM Scanning Laser System® de acordo com as instruções contidas no manual do aparelho. Foram comparados os valores obtidos nesse exame em um grupo de pacientes com equivalente esférico positivo e em um outro com este valor nulo ou negativo, pelo teste de Mann-Whitney. Resultados: Não se verificou diferença estatística entre os valores obtidos nos olhos de pacientes do grupo I e os do grupo II. Não foi encontrada correlação entre o equivalente esférico e os valores obtidos com o GDX TM Scanning Laser System®. Conclusões: Na amostra estudada não houve diferença estatística entre os valores obtidos em um grupo de olhos com equivalente esférico positivo e outro com este valor negativo ou nulo, usando-se o GDX TM Scanning Laser System®.Purpose: To evaluate the effect of spherical equivalent on the acquisition of nerve fiber layer (NFL thickness with GDX TM Scanning Laser System®. Methods: Forty-one eyes of 41 volunteers were enrolled in this study. All of them presented with no ocular disease and no visual field defect. The NFL thickness was measured with GDX TM Scanning Laser System® as described in its manual. The values obtained in a group of volunteers with negative spherical equivalent (group I were compared to those from a group with a positive spherical equivalent (group II by the Mann-Whitney test. Results: There was no statistical difference between mea-surements in eyes of group I and those in group II. The NFL thickness measurements were not correlated with the sphe-rical equivalent. Conclusions: In the studied group there was no statistical difference in the GDX TM Scanning Laser System® parameters related to spherical equivalent.

  6. Spectroscopic, scanning laser OBIC, and I-V/QE characterizations of browned EVA solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Pern, F.J. [National Renewable Energy Lab., Golden, CO (United States); Eisgruber, I.L. [Materials Research Group, Inc., Wheat Ridge, CO (United States); Micheels, R.H. [Polestar Technologies, Inc., Needham Hts, MA (United States)

    1996-05-01

    The effects of ethylene-vinyl acetate (EVA) discoloration due to accelerated field or laboratory exposure on the encapsulated silicon (Si) solar cells or EVA/glass laminates were characterized quantitatively by using non-invasive, non-destructive ultraviolet-visible (UV-vis) spectrophotometry, spectrocolorimetry, spectrofluorometry, scanning laser OBIC (optical beam induced current) spectroscopy, and current-voltage (I-V) and quantum efficiency (QE) measurements. The results show that the yellowness index (YI) measured directly over the AR-coated solar cells under the glass superstrate increased from the range of -80 to -90 to the range of -20 to 15 as the EVA changed from clear to brown. The ratio of two fluorescence emission peak areas generally increased from 1.45 to 5.69 as browning increased, but dropped to 4.21 on a darker EVA. For a solar cell with brown EVA in the central region, small-area grating QE measurements and scanning laser OBIC analysis between the brown and clear EVA regions showed that the quantum efficiency loss at 633 nm was 42%-48% of the loss at 488 nm, due to a reduced decrease of transmittance in browned EVA at the longer wavelengths. The portion of the solar cell under the browned EVA showed a decrease of {approximately}36% in efficiency, as compared to the cell efficiency under clear EVA. Transmittance loss at 633 nm was 38% of the loss at 488 nm for a light yellow-brown EVA/glass laminate that showed a small increase of 10 in the yellowness index.

  7. Robust Locally Weighted Regression For Ground Surface Extraction In Mobile Laser Scanning 3D Data

    Directory of Open Access Journals (Sweden)

    A. Nurunnabi

    2013-10-01

    Full Text Available A new robust way for ground surface extraction from mobile laser scanning 3D point cloud data is proposed in this paper. Fitting polynomials along 2D/3D points is one of the well-known methods for filtering ground points, but it is evident that unorganized point clouds consist of multiple complex structures by nature so it is not suitable for fitting a parametric global model. The aim of this research is to develop and implement an algorithm to classify ground and non-ground points based on statistically robust locally weighted regression which fits a regression surface (line in 2D by fitting without any predefined global functional relation among the variables of interest. Afterwards, the z (elevation-values are robustly down weighted based on the residuals for the fitted points. The new set of down weighted z-values along with x (or y values are used to get a new fit of the (lower surface (line. The process of fitting and down-weighting continues until the difference between two consecutive fits is insignificant. Then the final fit represents the ground level of the given point cloud and the ground surface points can be extracted. The performance of the new method has been demonstrated through vehicle based mobile laser scanning 3D point cloud data from urban areas which include different problematic objects such as short walls, large buildings, electric poles, sign posts and cars. The method has potential in areas like building/construction footprint determination, 3D city modelling, corridor mapping and asset management.

  8. Automatic Feature Detection, Description and Matching from Mobile Laser Scanning Data and Aerial Imagery

    Science.gov (United States)

    Hussnain, Zille; Oude Elberink, Sander; Vosselman, George

    2016-06-01

    In mobile laser scanning systems, the platform's position is measured by GNSS and IMU, which is often not reliable in urban areas. Consequently, derived Mobile Laser Scanning Point Cloud (MLSPC) lacks expected positioning reliability and accuracy. Many of the current solutions are either semi-automatic or unable to achieve pixel level accuracy. We propose an automatic feature extraction method which involves utilizing corresponding aerial images as a reference data set. The proposed method comprise three steps; image feature detection, description and matching between corresponding patches of nadir aerial and MLSPC ortho images. In the data pre-processing step the MLSPC is patch-wise cropped and converted to ortho images. Furthermore, each aerial image patch covering the area of the corresponding MLSPC patch is also cropped from the aerial image. For feature detection, we implemented an adaptive variant of Harris-operator to automatically detect corner feature points on the vertices of road markings. In feature description phase, we used the LATCH binary descriptor, which is robust to data from different sensors. For descriptor matching, we developed an outlier filtering technique, which exploits the arrangements of relative Euclidean-distances and angles between corresponding sets of feature points. We found that the positioning accuracy of the computed correspondence has achieved the pixel level accuracy, where the image resolution is 12cm. Furthermore, the developed approach is reliable when enough road markings are available in the data sets. We conclude that, in urban areas, the developed approach can reliably extract features necessary to improve the MLSPC accuracy to pixel level.

  9. Apertureless near-field scanning optical microscope working with or without laser source.

    Science.gov (United States)

    Formanek, F; De Wilde, Y; Aigouy, L; Chen, Y

    2004-01-01

    An apertureless near-field scanning optical microscope (ANSOM), used indifferent configurations, is presented. Our versatile home-made setup, based on a sharp tungsten tip glued onto a quartz tuning fork and working in tapping mode, allows to perform imaging over a broad spectral range. We have recorded optical images in the visible (wavelength, lambda = 655 nm) and in the infrared (lambda = 10.6 microm), proving that the setup routinely achieves an optical resolution of images recorded in the visible (lambda = 655 nm) in an inverted configuration where the tip does not perturb the focused spot of the illumination laser. Approach curves as well as image profiles have revealed that on demodulating the optical signal at higher harmonics, we can obtain an effective probe sharpening which results in an improvement of the resolution. Finally, we have presented optical images recorded in the infrared without any illumination, that is, the usual laser source is replaced by a simple heating of the sample. This has shown that the ANSOM can be used as a near-field thermal optical microscope (NTOM) to probe the near field generated by the thermal emission of the sample.

  10. Combining ESPI with laser scanning for 3D characterization of racing tyres sections

    Science.gov (United States)

    Pagliarulo, Vito; Farroni, Flavio; Ferraro, Pietro; Lanzotti, Antonio; Martorelli, Massimo; Memmolo, Pasquale; Speranza, Domenico; Timpone, Francesco

    2018-05-01

    In this work is exploited the possibility to use two optical techniques and combining their measurements for the 3D characterization of different tyres with particular attention to the tyre's section. Electronic Speckle Pattern Interferometry (ESPI) and Laser Scanner (LS) based on principle of triangulation have been employed for investigating and studying the tyre's section and 3D shape respectively. As case studies two different racing tyres, Michelin S9H and Pirelli Diablo respectively, have been considered. The investigation has been focused at the aim to evaluate and measure the section's components in order to add to the 3D model obtained by Laser Scanning accurate information about the different layers along through the tyres sections. It is important to note that the assessment about the different layers along the section is a very difficult task to obtain by visual inspection or classical microscopy and even with the LS. Here we demonstrate that the different layers can be easily highlighted and identified by mean of the ESPI.

  11. Possibilities of a Personal Laser Scanning System for Forest Mapping and Ecosystem Services

    Directory of Open Access Journals (Sweden)

    Xinlian Liang

    2014-01-01

    Full Text Available A professional-quality, personal laser scanning (PLS system for collecting tree attributes was demonstrated in this paper. The applied system, which is wearable by human operators, consists of a multi-constellation navigation system and an ultra-high-speed phase-shift laser scanner mounted on a rigid baseplate and consisting of a single sensor block. A multipass-corridor-mapping method was developed to process PLS data and a 2,000 m2 forest plot was utilized in the test. The tree stem detection accuracy was 82.6%; the root mean square error (RMSE of the estimates of tree diameter at breast height (DBH was 5.06 cm; the RMSE of the estimates of tree location was 0.38 m. The relative RMSE of the DBH estimates was 14.63%. The results showed, for the first time, the potential of the PLS system in mapping large forest plots. Further research on mapping accuracy in various forest conditions, data correction methods and multi-sensoral positioning techniques is needed. The utilization of this system in different applications, such as harvester operations, should also be explored. In addition to collecting tree-level and plot-level data for forest inventory, other possible applications of PLS for forest ecosystem services include mapping of canopy gaps, measuring leaf area index of large areas, documenting and visualizing forest routes feasible for recreation, hiking and berry and mushroom picking.

  12. Possibilities of a Personal Laser Scanning System for Forest Mapping and Ecosystem Services

    Science.gov (United States)

    Liang, Xinlian; Kukko, Antero; Kaartinen, Harri; Hyyppä, Juha; Yu, Xiaowei; Jaakkola, Anttoni; Wang, Yunsheng

    2014-01-01

    A professional-quality, personal laser scanning (PLS) system for collecting tree attributes was demonstrated in this paper. The applied system, which is wearable by human operators, consists of a multi-constellation navigation system and an ultra-high-speed phase-shift laser scanner mounted on a rigid baseplate and consisting of a single sensor block. A multipass-corridor-mapping method was developed to process PLS data and a 2,000 m2 forest plot was utilized in the test. The tree stem detection accuracy was 82.6%; the root mean square error (RMSE) of the estimates of tree diameter at breast height (DBH) was 5.06 cm; the RMSE of the estimates of tree location was 0.38 m. The relative RMSE of the DBH estimates was 14.63%. The results showed, for the first time, the potential of the PLS system in mapping large forest plots. Further research on mapping accuracy in various forest conditions, data correction methods and multi-sensoral positioning techniques is needed. The utilization of this system in different applications, such as harvester operations, should also be explored. In addition to collecting tree-level and plot-level data for forest inventory, other possible applications of PLS for forest ecosystem services include mapping of canopy gaps, measuring leaf area index of large areas, documenting and visualizing forest routes feasible for recreation, hiking and berry and mushroom picking. PMID:24434879

  13. Putting the Scanning Laser Environmental Airborne Fluorosensor through its paces : initial test results

    International Nuclear Information System (INIS)

    Brown, C.E.; Fingas, M.F.; Mullin, J.V.; Dick, R.; Giroud, C.

    1998-01-01

    The development and construction of a remote sensing system used to detect and map oil and related petroleum products in complex marine and shoreline environments was reviewed. The Scanning Laser Environmental Airborne Fluorosensor (SLEAF) system will be integrated into Environment Canada's DC-3 aircraft and will be undergoing extensive testing to verify its functionality in an airborne environment. Laser fluorosensors are the only sensors that can successfully detect oil in most environments including snow and ice. One of the roles of SLEAF will be to confirm or reject suspected oil contamination sites that have been targeted by infrared or visible spectral cameras. The ability of the SLEAF system to detect, classify and estimate oil coverage has been tested using a total of twenty-one oils ranging from light refined crude through to heavy refined oils. The aromatic content of the oils varied between 13 and 52 per cent and the API gravities of the oils tested varied from 11.9 to 48.6. 10 refs., 2 tabs., 2 figs

  14. Study of Subtropical Forestry Index Retrieval Using Terrestrial Laser Scanning and Hemispherical Photography

    Directory of Open Access Journals (Sweden)

    Ting Yun

    2015-01-01

    Full Text Available In order to retrieve gap fraction, leaf inclination angle, and leaf area index (LAI of subtropical forestry canopy, here we acquired forestry detailed information by means of hemispherical photography, terrestrial laser scanning, and LAI-2200 plant canopy analyzer. Meanwhile, we presented a series of image processing and computer graphics algorithms that include image and point cloud data (PCD segmentation methods for branch and leaf classification and PCD features, such as normal vector, tangent plane extraction, and hemispherical projection method for PCD coordinate transformation. In addition, various forestry mathematical models were proposed to deduce forestry canopy indexes based on the radiation transfer model of Beer-Lambert law. Through the comparison of the experimental results on many plot samples, the terrestrial laser scanner- (TLS- based index estimation method obtains results similar to digital hemispherical photograph (HP and LAI-2200 plant canopy analyzer taken of the same stands and used for validation. It indicates that the TLS-based algorithm is able to capture the variability in LAI of forest stands with a range of densities, and there is a high chance to enhance TLS as a calibration tool for other devices.

  15. Calculating point of origin of blood spatter using laser scanning technology.

    Science.gov (United States)

    Hakim, Nashad; Liscio, Eugene

    2015-03-01

    The point of origin of an impact pattern is important in establishing the chain of events in a bloodletting incident. In this study, the accuracy and reproducibility of the point of origin estimation using the FARO Scene software with the FARO Focus(3D) laser scanner was determined. Five impact patterns were created for each of three combinations of distances from the floor (z) and the front wall (x). Fifteen spatters were created using a custom impact rig, scanned using the laser scanner, photographed using a DSLR camera, and processed using the Scene software. Overall results gave a SD = 3.49 cm (p < 0.0001) in the x-direction, SD = 1.14 cm (p = 0.9291) in the y-direction, and SD = 9.08 cm (p < 0.0115) in the z-direction. The technique performs within literature ranges of accepted accuracy and reproducibility and is comparable to results reported for other virtual stringing software. © 2015 American Academy of Forensic Sciences.

  16. Assessing biomass based on canopy height profiles using airborne laser scanning data in eucalypt plantations

    Directory of Open Access Journals (Sweden)

    André Gracioso Peres Silva

    2015-12-01

    Full Text Available This study aimed to map the stem biomass of an even-aged eucalyptus plantation in southeastern Brazil based on canopy height profile (CHPs statistics using wall-to-wall discrete return airborne laser scanning (ALS, and compare the results with alternative maps generated by ordinary kriging interpolation from field-derived measurements. The assessment of stem biomass with ALS data was carried out using regression analysis methods. Initially, CHPs were determined to express the distribution of laser point heights in the ALS cloud for each sample plot. The probability density function (pdf used was the Weibull distribution, with two parameters that in a secondary task, were used as explanatory variables to model stem biomass. ALS metrics such as height percentiles, dispersion of heights, and proportion of points were also investigated. A simple linear regression model of stem biomass as a function of the Weibull scale parameter showed high correlation (adj.R2 = 0.89. The alternative model considering the 30th percentile and the Weibull shape parameter slightly improved the quality of the estimation (adj.R2 = 0.93. Stem biomass maps based on the Weibull scale parameter doubled the accuracy of the ordinary kriging approach (relative root mean square error = 6 % and 13 %, respectively.

  17. 3D laser scanning and open source GIS for solar potential assessment

    International Nuclear Information System (INIS)

    Jochem, A.

    2011-01-01

    There is an increasing demand among home owners and operators of commercial and public facilities to reduce energy costs, the reliance on declining fossil fuel resources and the impact on the environment. Therefore, cost effective sustainable energy production such as biomass, wind power and solar energy must play a major role in the energy supply chain. The latter is in the focus of this thesis. Solar thermal and photovoltaic conversion systems can be mounted on both, roof planes and building facades in order to produce heat and electricity and thus to increase renewable energy supply. The amount of the incoming solar energy on building areas can be assessed by using e.g. solar radiation models that are implemented in Geographical Information Systems (GIS). However, this requires detailed information about the three dimensional representation of the buildings of interest as well as of their surrounding objects that may cast shadows in order to find suitable areas for the installation of solar based renewable energy technologies. In recent years Light Detection and Ranging (LiDAR), also referred to as laser scanning, has established as a standard technology for highly accurate three dimensional data acquisition of object surfaces. The geometrical information of the scanned surface is stored as 3D point cloud (xyz-triples). Each point is tagged with additional information such as strength of backscatter (intensity), timestamp and scan angle. Most solar radiation models that are implemented in standard GIS software operate on 2.5D raster data and cannot be combined with 3D point cloud data. Hence, an aggregation and simplification of the 3D point cloud to 2.5D raster cells is required leading to an irreversible loss of the third dimension. This procedure reduces the amount of point cloud data significantly and processing such simple data models is less time consuming because the complexity of the third dimension has not to be considered anymore. Although 3D shapes

  18. SUPPORTING UAVS IN LOW VISIBILITY CONDITIONS BY MULTIPLE-PULSE LASER SCANNING DEVICES

    Directory of Open Access Journals (Sweden)

    A. Djuricic

    2013-04-01

    Full Text Available Unmanned Aerial Vehicles (UAVs are nowadays promising platforms for capturing spatial information, because they are low cost solutions, which are easy to bring to the surveying field and can operate automatically. Usually these devices are equipped with visual sensors to support the navigation of the platform or to transmit observations of the environment to the operator. By collecting the data and processing the captured images even an estimation of the observed environment in form of 3D information is available. Therefore Simultaneous Localization and Mapping (SLAM algorithms are well known for processing data which is captured in the visible domain. However, situations can occur where gathering visual information is difficult due to given limitations in form of low visibility. For example if soft obstacles in form of translucent materials are given in disaster scenarios with smoke and operating has still to be ensured, active optical sensors (e.g. laser scanners are gaining interest because they can penetrate the soft obstacle and allow to acquire information behind it. A new lightweight (210 g, simplified and minimized scanning unit is now available which allows to capture multiple reflections for each transmitted laser pulse, namely the Hokuyo UTM-30LX-EW. With such a device, it is possible to overcome the above mentioned restrictions or limitations of low visibility by soft obstacles and even measure under critical circumstances. A multi-pulse system can provide accurate measurements on, within, and behind the soft obstacle. This research focuses on investigating the ability and performance of a laser scanner to penetrate the soft obstacle. Thus, investigations on a system that overcomes these limitations and provides a solution will be given. First promising experimental results considering soft obstacle are described.

  19. Comparison of pain scores between patients undergoing panretinal photocoagulation using navigated or pattern scan laser systems

    Directory of Open Access Journals (Sweden)

    Umit Ubeyt Inan

    2016-02-01

    Full Text Available ABSTRACT Purpose: To compare the pain responses of patients with proliferative diabetic retinopathy (PDR undergoing panretinal photocoagulation (PRP using either pattern scan laser (PASCAL or navigated laser photocoagulation (NAVILAS. Methods: Patients diagnosed with PDR were randomly assigned to undergo either PASCAL or NAVILAS photocoagulation treatment. PRP was performed using the multi-shot mode with a spot size of 200-400 µm and a pulse duration of 30 ms to obtain a white-grayish spot on the retina. Parameters were identical in both procedures. After 30 min of PRP application, patients were asked to verbally describe their pain perception as either "none," "mild," "moderate," "severe," or "very severe" using a verbal rating scale (VRS and visual analog scale (VAS by indicating a score from "0" to "10," representing the severity of pain from "no pain" to "severe pain." Results: A total of 60 eyes of 60 patients (20 females and 40 males diagnosed with PDR were treated. The mean age of patients was 62.22 ± 9.19 years, and the mean diabetes duration was 195.47 ± 94.54 months. The mean number of laser spots delivered during PRP was 389.47 ± 71.52 in the NAVILAS group and 392.70 ± 54.33 in the PASCAL group (p=0.57. The difference in pain responses between patients in the NAVILAS and PASCAL groups was significant with regard to the mean VRS (1.10 ± 0.67 and 1.47 ± 0.69, respectively; p=0.042 and mean VAS (2.13 ± 1.17 and 2.97 ± 1.35, respectively; p=0.034 scores. Conclusions: Pain responses in patients undergoing PRP with a 30-ms pulse duration were significantly milder in the NAVILAS group than in the PASCAL group.

  20. Electrolytic etching of fine stainless-steel pipes patterned by laser-scan lithography

    Science.gov (United States)

    Takahashi, Hiroshi; Sagara, Tomoya; Horiuchi, Toshiyuki

    2017-07-01

    Recently, it is required to develop a method for fabricating cylindrical micro-components in the field of measurement and medical engineering. Here, electrolytic etching of fine stainless-steel pipes patterned by laser-scan lithography was researched. The pipe diameter was 100 μm. At first, a pipe coated with 3-7 μm thick positive resist (tok, PMER P LA-900) was exposed to a violet laser beam with a wavelength of 408 nm (Neoark,TC20-4030-45). The laser beam was reshaped in a circle by placing a pinhole, and irradiated on the pipe by reducing the size in 1/20 using a reduction projection optics. Linearly arrayed 22 slit patterns with a width of 25 μm and a length of 175 μm were delineated in every 90-degree circumferential direction. That is, 88 slits in total were delineated at an exposure speed of 110 μm/s. In the axial direction, patterns were delineated at intervals of 90 μm. Following the pattern delineation, the pipe masked by the resist patterns was electrolytically etched. The pipe was used as an anode and an aluminum cylinder was set as a cathode around the pipe. As the electrolyte, aqueous solution of NaCl and NH4Cl was used. After etching the pipe, the resist was removed by ultrasonic cleaning in acetone. Although feasibility for fabricating multi-slit pipes was demonstrated, sizes of the etched slits were enlarged being caused by the undercut, and the shapes were partially deformed, and all the pipes were snapped at the chuck side.

  1. Elastomeric photo-actuators and their investigation by confocal laser scanning microscopy

    International Nuclear Information System (INIS)

    Czaniková, Klaudia; Ilčíková, Markéta; Mičušík, Matej; Kasák, Peter; Mosnáček, Jaroslav; Omastová, Mária; Krupa, Igor; Pavlova, Ewa; Chorvát Jr, Dušan

    2013-01-01

    The photo-actuation behavior of nanocomposites based on ethylene–vinylacetate copolymer (EVA) and styrene–isoprene–styrene (SIS) block copolymer filled with well-dispersed and modified multiwalled carbon nanotubes (MWCNTs) is discussed in this paper. The nanocomposites were prepared by casting from solution. To improve the dispersion of the MWCNTs in EVA, the MWCNT surface was modified with a non-covalent surfactant, cholesteryl 1-pyrenecarboxylate (PyChol). To prepare SIS nanocomposites, the MWCNT surface was covalently modified with polystyrene chains. The good dispersion of the filler was confirmed by transmission electron microscopy (TEM). Special, custom-made punch/die molds were used to create a Braille element (BE)-like shape, which under shear forces induces a uniaxial orientation of the MWCNTs within the matrix. The uniaxial orientation of MWCNTs is an essential precondition to ensure the photo-actuating behavior of MWCNTs in polymeric matrices. The orientation of the MWCNTs within the matrices was examined by scanning electron microscopy (SEM). Nanocomposite BEs were illuminated from the bottom by a red light-emitting diode (LED), and the photo-actuation was investigated by confocal laser scanning microscopy (CLSM). When the BEs were exposed to light, a temporary increase in the height of the element was detected. This process was observed to be reversible: after switching off the light, the BEs returned to their original shape and height. (paper)

  2. MIMIC: An Innovative Methodology for Determining Mobile Laser Scanning System Point Density

    Directory of Open Access Journals (Sweden)

    Conor Cahalane

    2014-08-01

    Full Text Available Understanding how various Mobile Mapping System (MMS laser hardware configurations and operating parameters exercise different influence on point density is important for assessing system performance, which in turn facilitates system design and MMS benchmarking. Point density also influences data processing, as objects that can be recognised using automated algorithms generally require a minimum point density. Although obtaining the necessary point density impacts on hardware costs, survey time and data storage requirements, a method for accurately and rapidly assessing MMS performance is lacking for generic MMSs. We have developed a method for quantifying point clouds collected by an MMS with respect to known objects at specified distances using 3D surface normals, 2D geometric formulae and line drawing algorithms. These algorithms were combined in a system called the Mobile Mapping Point Density Calculator (MIMIC and were validated using point clouds captured by both a single scanner and a dual scanner MMS. Results from MIMIC were promising: when considering the number of scan profiles striking the target, the average error equated to less than 1 point per scan profile. These tests highlight that MIMIC is capable of accurately calculating point density for both single and dual scanner MMSs.

  3. Characterization of ultrashort laser pulses employing self-phase modulation dispersion-scan technique

    Science.gov (United States)

    Sharba, A. B.; Chekhlov, O.; Wyatt, A. S.; Pattathil, R.; Borghesi, M.; Sarri, G.

    2018-03-01

    We present a new phase characterization technique for ultrashort laser pulses that employs self-phase modulation (SPM) in the dispersion scan approach. The method can be implemented by recording a set of nonlinearly modulated spectra generated with a set of known chirp values. The unknown phase of the pulse is retrieved by linking the recorded spectra to the initial spectrum of the pulse via a phase function guessed by a function minimization iterative algorithm. This technique has many advantages over the dispersion scan techniques that use frequency conversion processes. Mainly, the use of SPM cancels out the phase and group velocity mismatch errors and dramatically widens the spectral acceptance of the nonlinear medium and the range of working wavelength. The robustness of the technique is demonstrated with smooth and complex phase retrievals using numerical examples. The method is shown to be not affected by the spatial distribution of the beam or the presence of nonlinear absorption process. In addition, we present an efficient method for phase representation based on a summation of a set of Gaussian functions. The independence of the functions from each other prevents phase coupling of any kind and facilitates a flexible phase representation.

  4. Fast Edge Detection and Segmentation of Terrestrial Laser Scans Through Normal Variation Analysis

    Science.gov (United States)

    Che, E.; Olsen, M. J.

    2017-09-01

    Terrestrial Laser Scanning (TLS) utilizes light detection and ranging (lidar) to effectively and efficiently acquire point cloud data for a wide variety of applications. Segmentation is a common procedure of post-processing to group the point cloud into a number of clusters to simplify the data for the sequential modelling and analysis needed for most applications. This paper presents a novel method to rapidly segment TLS data based on edge detection and region growing. First, by computing the projected incidence angles and performing the normal variation analysis, the silhouette edges and intersection edges are separated from the smooth surfaces. Then a modified region growing algorithm groups the points lying on the same smooth surface. The proposed method efficiently exploits the gridded scan pattern utilized during acquisition of TLS data from most sensors and takes advantage of parallel programming to process approximately 1 million points per second. Moreover, the proposed segmentation does not require estimation of the normal at each point, which limits the errors in normal estimation propagating to segmentation. Both an indoor and outdoor scene are used for an experiment to demonstrate and discuss the effectiveness and robustness of the proposed segmentation method.

  5. Design of a Compact, Bimorph Deformable Mirror-Based Adaptive Optics Scanning Laser Ophthalmoscope.

    Science.gov (United States)

    He, Yi; Deng, Guohua; Wei, Ling; Li, Xiqi; Yang, Jinsheng; Shi, Guohua; Zhang, Yudong

    2016-01-01

    We have designed, constructed and tested an adaptive optics scanning laser ophthalmoscope (AOSLO) using a bimorph mirror. The simulated AOSLO system achieves diffraction-limited criterion through all the raster scanning fields (6.4 mm pupil, 3° × 3° on pupil). The bimorph mirror-based AOSLO corrected ocular aberrations in model eyes to less than 0.1 μm RMS wavefront error with a closed-loop bandwidth of a few Hz. Facilitated with a bimorph mirror at a stroke of ±15 μm with 35 elements and an aperture of 20 mm, the new AOSLO system has a size only half that of the first-generation AOSLO system. The significant increase in stroke allows for large ocular aberrations such as defocus in the range of ±600° and astigmatism in the range of ±200°, thereby fully exploiting the AO correcting capabilities for diseased human eyes in the future.

  6. Detecting Changes in Forest Structure over Time with Bi-Temporal Terrestrial Laser Scanning Data

    Directory of Open Access Journals (Sweden)

    Timo Melkas

    2012-10-01

    Full Text Available Changes to stems caused by natural forces and timber harvesting constitute an essential input for many forestry-related applications and ecological studies, especially forestry inventories based on the use of permanent sample plots. Conventional field measurement is widely acknowledged as being time-consuming and labor-intensive. More automated and efficient alternatives or supportive methods are needed. Terrestrial laser scanning (TLS has been demonstrated to be a promising method in forestry field inventories. Nevertheless, the applicability of TLS in recording changes in the structure of forest plots has not been studied in detail. This paper presents a fully automated method for detecting changes in forest structure over time using bi-temporal TLS data. The developed method was tested on five densely populated forest plots including 137 trees and 50 harvested trees in point clouds. The present study demonstrated that 90 percent of tree stem changes could be automatically located from single-scan TLS data. These changes accounted for 92 percent of the changed basal area. The results indicate that the processing of TLS data collected at different times to detect tree stem changes can be fully automated.

  7. Can Low-Resolution Airborne Laser Scanning Data Be Used to Model Stream Rating Curves?

    Directory of Open Access Journals (Sweden)

    Steve W. Lyon

    2015-03-01

    Full Text Available This pilot study explores the potential of using low-resolution (0.2 points/m2 airborne laser scanning (ALS-derived elevation data to model stream rating curves. Rating curves, which allow the functional translation of stream water depth into discharge, making them integral to water resource monitoring efforts, were modeled using a physics-based approach that captures basic geometric measurements to establish flow resistance due to implicit channel roughness. We tested synthetically thinned high-resolution (more than 2 points/m2 ALS data as a proxy for low-resolution data at a point density equivalent to that obtained within most national-scale ALS strategies. Our results show that the errors incurred due to the effect of low-resolution versus high-resolution ALS data were less than those due to flow measurement and empirical rating curve fitting uncertainties. As such, although there likely are scale and technical limitations to consider, it is theoretically possible to generate rating curves in a river network from ALS data of the resolution anticipated within national-scale ALS schemes (at least for rivers with relatively simple geometries. This is promising, since generating rating curves from ALS scans would greatly enhance our ability to monitor streamflow by simplifying the overall effort required.

  8. Sparse Density, Leaf-Off Airborne Laser Scanning Data in Aboveground Biomass Component Prediction

    Directory of Open Access Journals (Sweden)

    Ville Kankare

    2015-05-01

    Full Text Available The demand for cost-efficient forest aboveground biomass (AGB prediction methods is growing worldwide. The National Land Survey of Finland (NLS began collecting airborne laser scanning (ALS data throughout Finland in 2008 to provide a new high-detailed terrain elevation model. Similar data sets are being collected in an increasing number of countries worldwide. These data sets offer great potential in forest mapping related applications. The objectives of our study were (i to evaluate the AGB component prediction accuracy at a resolution of 300 m2 using sparse density, leaf-off ALS data (collected by NLS derived metrics as predictor variables; (ii to compare prediction accuracies with existing large-scale forest mapping techniques (Multi-source National Forest Inventory, MS-NFI based on Landsat TM satellite imagery; and (iii to evaluate the accuracy and effect of canopy height model (CHM derived metrics on AGB component prediction when ALS data were acquired with multiple sensors and varying scanning parameters. Results showed that ALS point metrics can be used to predict component AGBs with an accuracy of 29.7%–48.3%. AGB prediction accuracy was slightly improved using CHM-derived metrics but CHM metrics had a more clear effect on the estimated bias. Compared to the MS-NFI, the prediction accuracy was considerably higher, which was caused by differences in the remote sensing data utilized.

  9. Extracting Rail Track Geometry from Static Terrestrial Laser Scans for Monitoring Purposes

    Directory of Open Access Journals (Sweden)

    A. Soni

    2014-06-01

    Full Text Available This paper presents the capabilities of detecting relevant geometry of railway track for monitoring purposes from static terrestrial laser scanning (TLS systems at platform level. The quality of the scans from a phased based scanner (Scanner A and a hybrid timeof- flight scanner (Scanner B are compared by fitting different sections of the track profile to its matching standardised rail model. The various sections of track investigated are able to fit to the model with an RMS of less than 3 mm. Both scanners show that once obvious noise and artefacts have been removed from the data, the most confident fit of the point cloud to the model is the section closest to the scanner position. The results of the fit highlight the potential to use this method as a bespoke track monitoring tool during major redevelopment projects where traditional methods, such as robotic total stations, results in missed information, for example due to passing trains or knocked prisms and must account for offset target locations to compute track parameters.

  10. Scanning laser Doppler imaging may predict disease progression of localized scleroderma in children and young adults.

    Science.gov (United States)

    Shaw, L J; Shipley, J; Newell, E L; Harris, N; Clinch, J G; Lovell, C R

    2013-07-01

    Localized scleroderma is a rare but potentially disfiguring and disabling condition. Systemic treatment should be started early in those with active disease in key functional and cosmetic sites, but disease activity is difficult to determine clinically. Superficial blood flow has been shown to correlate with disease activity in localized scleroderma. To examine whether superficial blood flow measured by laser Doppler imaging (LDI) has the potential to predict disease progression and therefore select patients for early systemic treatment. A group of 20 individuals had clinical assessment and scanning LDI blood-flow measurements of 32 affected body sites. After a mean follow-up of 8.7 months their clinical outcome was compared with the results of the initial LDI assessment. Eleven out of 15 patients with an assessment of active LDI had progressed clinically, and 16 out of the 17 scans with inactive LDI assessment had not progressed, giving a positive predictive value of 73% and a negative predictive value of 94%. We believe that LDI can be a useful tool in predicting disease progression in localized scleroderma, and it may help clinicians to decide which patients to treat early. © 2013 The Authors BJD © 2013 British Association of Dermatologists.

  11. Can low-resolution airborne laser scanning data be used to model stream rating curves?

    Science.gov (United States)

    Lyon, Steve; Nathanson, Marcus; Lam, Norris; Dahlke, Helen; Rutzinger, Martin; Kean, Jason W.; Laudon, Hjalmar

    2015-01-01

    This pilot study explores the potential of using low-resolution (0.2 points/m2) airborne laser scanning (ALS)-derived elevation data to model stream rating curves. Rating curves, which allow the functional translation of stream water depth into discharge, making them integral to water resource monitoring efforts, were modeled using a physics-based approach that captures basic geometric measurements to establish flow resistance due to implicit channel roughness. We tested synthetically thinned high-resolution (more than 2 points/m2) ALS data as a proxy for low-resolution data at a point density equivalent to that obtained within most national-scale ALS strategies. Our results show that the errors incurred due to the effect of low-resolution versus high-resolution ALS data were less than those due to flow measurement and empirical rating curve fitting uncertainties. As such, although there likely are scale and technical limitations to consider, it is theoretically possible to generate rating curves in a river network from ALS data of the resolution anticipated within national-scale ALS schemes (at least for rivers with relatively simple geometries). This is promising, since generating rating curves from ALS scans would greatly enhance our ability to monitor streamflow by simplifying the overall effort required.

  12. DIGITAL TERRAIN MODELS FROM MOBILE LASER SCANNING DATA IN MORAVIAN KARST

    Directory of Open Access Journals (Sweden)

    N. Tyagur

    2016-06-01

    Full Text Available During the last ten years, mobile laser scanning (MLS systems have become a very popular and efficient technology for capturing reality in 3D. A 3D laser scanner mounted on the top of a moving vehicle (e.g. car allows the high precision capturing of the environment in a fast way. Mostly this technology is used in cities for capturing roads and buildings facades to create 3D city models. In our work, we used an MLS system in Moravian Karst, which is a protected nature reserve in the Eastern Part of the Czech Republic, with a steep rocky terrain covered by forests. For the 3D data collection, the Riegl VMX 450, mounted on a car, was used with integrated IMU/GNSS equipment, which provides low noise, rich and very dense 3D point clouds. The aim of this work is to create a digital terrain model (DTM from several MLS data sets acquired in the neighbourhood of a road. The total length of two covered areas is 3.9 and 6.1 km respectively, with an average width of 100 m. For the DTM generation, a fully automatic, robust, hierarchic approach was applied. The derivation of the DTM is based on combinations of hierarchical interpolation and robust filtering for different resolution levels. For the generation of the final DTMs, different interpolation algorithms are applied to the classified terrain points. The used parameters were determined by explorative analysis. All MLS data sets were processed with one parameter set. As a result, a high precise DTM was derived with high spatial resolution of 0.25 x 0.25 m. The quality of the DTMs was checked by geodetic measurements and visual comparison with raw point clouds. The high quality of the derived DTM can be used for analysing terrain changes and morphological structures. Finally, the derived DTM was compared with the DTM of the Czech Republic (DMR 4G with a resolution of 5 x 5 m, which was created from airborne laser scanning data. The vertical accuracy of the derived DTMs is around 0.10 m.

  13. Determination Of Optimal Stope Strike Length On Steep Orebodies Through Laser Scanning At Lubambe Copper Zambia

    Directory of Open Access Journals (Sweden)

    Kalume H

    2017-08-01

    Full Text Available Lubambe Copper Mine is located in Chililabombwe Zambia and is a joint copper mining venture with three partners that include African Rainbow Minerals 40 Vale 40 and the Government of Zambia 20. The current mining method utilises Longitudinal Room and Pillar Mining LRP on 70m long panels strike length. However these long panels have resulted in unprecedented levels of dilution mainly from the collapse of hanging wall laminated ore shale OS2 leading to reduced recoveries. Observations made underground show high variability in geological and geotechnical conditions of the rock mass with factors such as weathering on joints lamina spaced joints and stress changes induced by mining all contributing to weakening and early collapse of the hanging wall. Therefore a study was undertaken to establish the optimal stope strike length of steep ore bodies at Lubambe. The exercise involved the use of Faro Laser Scanner every four stope rings blasted with time when the scan was performed noted. The spatial coherence of lasers makes them ideal measuring tools in situations where measurements need to be taken in inaccessible areas. Recent advances in laser scanning coupled with the exponential increase in processing power have greatly improved the methods used to estimate stope tonnages extracted from massive inaccessible stopes. The collected data was then used to construct digital three dimensional models of the stope contents. Sections were cut every metre with deformations taken and analysed with respect to time. Deformation rates from the hanging wall was reducing from 0.14thr to 0.07thr between rings 1 to 8. This reduction was as a result of slot blasting that involved drilling and blasting a number of holes at the same time. Between rings 8 to 25 deformation was constant averaging 0.28thr and between rings 26 and 28 a sharp increase in deformation rate was experienced from as low as 0.16thr to 6.33thr. This sharp increase defines the optimal stope length

  14. Monitoring informal settlements using SAR polarimetry

    CSIR Research Space (South Africa)

    Kleynhans, W

    2012-10-01

    Full Text Available for settlement mapping and detection has remained largely unexplored in Southern Africa. The objective of this study is to investigate the possible role that SAR polarimetry could play in the monitoring of informal settlements....

  15. Polarimetry of stars and planetary systems

    National Research Council Canada - National Science Library

    Kolokolova, Ludmilla; Hough, James; Levasseur-Regourd, Anny-Chantal

    2015-01-01

    "Summarizing the striking advances of the last two decades, this reliable introduction to modern astronomical polarimetry provides a comprehensive review of state-of-the-art techniques, models and research methods...

  16. Scanning laser densitometry and color perimetry demonstrate reduced photopigment density and sensitivity in two patients with retinal degeneration.

    Science.gov (United States)

    Tornow, R P; Stilling, R; Zrenner, E

    1999-10-01

    To test the feasibility of scanning laser densitometry with a modified Rodenstock scanning laser ophthalmoscope (SLO) to measure the rod and cone photopigment distribution in patients with retinal diseases. Scanning laser densitometry was performed using a modified Rodenstock scanning laser ophthalmoscope. The distribution of the photopigments was calculated from dark adapted and bleached images taken with the 514 nm laser of the SLO. This wavelength is absorbed by rod and cone photopigments. Discrimination is possible due to their different spatial distribution. Additionally, to measure retinal sensitivity profiles, dark adapted two color static perimetry with a Tübinger manual perimeter was performed along the horizontal meridian with 1 degree spacing. A patient with retinitis pigmentosa had slightly reduced photopigment density within the central +/- 5 degrees but no detectable photopigment for eccentricities beyond 5 degrees. A patient with cone dystrophy had nearly normal pigment density beyond +/- 5 degrees, but considerably reduced photopigment density within the central +/- 5 degrees. Within the central +/- 5 degrees, the patient with retinitis pigmentosa had normal sensitivity for the red stimulus and reduced sensitivity for the green stimulus. There was no measurable function beyond 7 degrees. The patient with cone dystrophy had normal sensitivity for the green stimulus outside the foveal center and reduced sensitivity for the red stimulus at the foveal center. The results of color perimetry for this patient with a central scotoma were probably influenced by eccentric fixation. Scanning laser densitometry with a modified Rodenstock SLO is a useful method to assess the human photopigment distribution. Densitometry results were confirmed by dark adapted two color static perimetry. Photopigment distribution and retinal sensitivity profiles can be measured with high spatial resolution. This may help to measure exactly the temporal development of retinal

  17. Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

    International Nuclear Information System (INIS)

    Yazaki, Akio; Kim, Chanju; Chan, Jacky; Mahjoubfar, Ata; Goda, Keisuke; Watanabe, Masahiro; Jalali, Bahram

    2014-01-01

    High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection en