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Sample records for attenuates laser-induced choroidal

  1. Laser-Induced Choroidal Neovascularizations: Clinical Study of 3 Cases

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    Wipada Laovirojjanakul

    2017-08-01

    Full Text Available Background: We report 3 patients with laser-induced choroidal neovascularization (CNV. Method: Retrospective, observational case series. Medical charts and photographs were reviewed. Results: Two patients with central serous chorioretinopathy who developed iatrogenic CNV after focal laser photocoagulation were treated with intravitreal ranibizumab injections. One patient with CNV secondary to thermal laser photocoagulation for diabetic macular edema was treated with photodynamic therapy (PDT. Visual improvement has been demonstrated in the patients treated with intravitreal ranibizumab injections, and their successful visual outcome was stable for more than 2 years. Stable visual acuity was also observed in the patient treated with PDT, no visual improvement was observed possibly due to the macular scar and macular ischemia. No systemic or ocular complications were detected among the 3 cases. Conclusion: To prevent a laser-induced CNV, it is critical to avoid heavy small-spot laser burns and repeated application. Patients should be monitored carefully for CNV after laser treatment. In our cases, PDT and intravitreal ranibizumab injections were effective for the treatment of laser-induced CNV.

  2. Intravitreal itraconazole inhibits laser-induced choroidal neovascularization in rats.

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    Jeong Hun Bae

    Full Text Available Choroidal neovascularization (CNV is a major cause of severe visual loss in patients with age-related macular degeneration (AMD. Recently, itraconazole has shown potent and dose-dependent inhibition of tumor-associated angiogenesis. We evaluated the anti-angiogenic effect of itraconazole in a rat model of laser-induced CNV. After laser photocoagulation in each eye to cause CNV, right eyes were administered intravitreal injections of itraconazole; left eyes received balanced salt solution (BSS as controls. On day 14 after laser induction, fluorescein angiography (FA was used to assess abnormal vascular leakage. Flattened retinal pigment epithelium (RPE-choroid tissue complex was stained with Alexa Fluor 594-conjugated isolectin B4 to measure the CNV area and volume. Vascular endothelial growth factor receptor 2 (VEGFR2 mRNA and protein expression was determined 1, 4, 7, and 14 days after intravitreal injection by quantitative RT-PCR or Western blot. VEGF levels were analyzed by enzyme-linked immunosorbent assay (ELISA. Intravitreal itraconazole significantly reduced leakage from CNV as assessed by FA and CNV area and volume on flat mounts compared with intravitreal BSS (p = 0.002 for CNV leakage, p<0.001 for CNV area and volume. Quantitative RT-PCR showed significantly lower expression of VEGFR2 mRNA in the RPE-choroid complexes of itraconazole-injected eyes than those of BSS-injected eyes on days 7 and 14 (p = 0.003 and p = 0.006. Western blots indicated that VEGFR2 was downregulated after itraconazole treatment. ELISA showed a significant difference in VEGF level between itraconazole-injected and BSS-injected eyes on days 7 and 14 (p = 0.04 and p = 0.001. Our study demonstrated that intravitreal itraconazole significantly inhibited the development of laser-induced CNV in rats. Itraconazole had anti-angiogenic activity along with the reduction of VEGFR2 and VEGF levels. Itraconazole may prove beneficial for treating CNV as an alternative or

  3. Heparanase-1 activities in the development of laser induced choroidal neovascularization

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    Bao-Ke Hou

    2013-04-01

    Full Text Available AIM:To investigate the role of heparanase-1 in laser-induced choroidal neovascularization (CNV.METHODS:Experimental CNV was induced by krypton laser photocoagulation in 15 male Brown Norway rats. Fundus fluorescein angiography and histopathological examination were performed in observing the CNV development. The expression and distribution of heparanase-1 protein in the laser lesions were determined by immunohistochemistry and western blotting analysis.RESULTS:The success rate of laser induced CNV was approximately 75% on 3-4 weeks after laser photocoagulation. The protein levels of heparanase-1 increased significantly in the retina-choroidal complex of CNV models when compared to normal rat eyes (P<0.01. Immunostaining confirmed strong heparanase-1 expressions in all laser lesions, and it displayed to be highest at the newly formed blood vessels within the fibrovascular complex in the subretinal space.CONCLUSION:Heparanase-1 is closely involved in the development of laser induced CNV.

  4. Optimization of an Image-Guided Laser-Induced Choroidal Neovascularization Model in Mice.

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    Yan Gong

    Full Text Available The mouse model of laser-induced choroidal neovascularization (CNV has been used in studies of the exudative form of age-related macular degeneration using both the conventional slit lamp and a new image-guided laser system. A standardized protocol is needed for consistent results using this model, which has been lacking. We optimized details of laser-induced CNV using the image-guided laser photocoagulation system. Four lesions with similar size were consistently applied per eye at approximately double the disc diameter away from the optic nerve, using different laser power levels, and mice of various ages and genders. After 7 days, the mice were sacrificed and retinal pigment epithelium/choroid/sclera was flat-mounted, stained with Isolectin B4, and imaged. Quantification of the area of the laser-induced lesions was performed using an established and constant threshold. Exclusion criteria are described that were necessary for reliable data analysis of the laser-induced CNV lesions. The CNV lesion area was proportional to the laser power levels. Mice at 12-16 weeks of age developed more severe CNV than those at 6-8 weeks of age, and the gender difference was only significant in mice at 12-16 weeks of age, but not in those at 6-8 weeks of age. Dietary intake of omega-3 long-chain polyunsaturated fatty acid reduced laser-induced CNV in mice. Taken together, laser-induced CNV lesions can be easily and consistently applied using the image-guided laser platform. Mice at 6-8 weeks of age are ideal for the laser-induced CNV model.

  5. Effects of ginkgo biloba extract on laser-induced choroidal neovascularization in rats

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    Chao Chen

    2013-11-01

    Full Text Available AIM: To investigate the effects of ginkgo biloba extract(EGb 761on laser-induced choroidal neovascularization(CNVin rats.METHODS: Totally 60 BN rats were randomly divided into 4 groups: normal control group, model group, experimental group, physiological saline group with 15 in each group. All CNV models were made by krypton laser. Rats in experimental group were intraperitoneally injected with 0.35% EGb761(100mg/kgevery day after laser exposure until they were sacrificed. Rats in physiological saline group were intraperitoneally injected physiological saline every day after laser exposure until they were sacrificed. Fundus fluorescein angiography(FFAwas performed on every rat on the 7th day, 14th day and the 21st day after laser exposure, then the rats were sacrificed immediately. The eyes were enucleated and processed for histopathologic examination.RESULTS: There was no choroidal fluorescein leakage staining in normal rats. There were obviously less choroidal fluorescein leakage points in experimental groups than that in the corresponding model groups(PCONCLUSION: EGb761 len inhibit the formation of laser-induced CNV in rats. The longer the time, the better curative effect.

  6. Melissa officinalis extract inhibits laser-induced choroidal neovascularization in a rat model.

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    Eun Kyoung Lee

    Full Text Available This study investigated the effect of Melissa officinalis extract on laser-induced choroidal neovascularization (CNV in a rat model. The mechanism by which M. officinalis extract acted was also investigated.Experimental CNV was induced by laser photocoagulation in Brown Norway rats. An active fraction of the Melissa leaf extract was orally administered (50 or 100 mg/kg/day beginning 3 days before laser photocoagulation and ending 14 days after laser photocoagulation. Optical coherence tomography and fluorescein angiography were performed in vivo to evaluate the thickness and leakage of CNV. Choroidal flat mount and histological analysis were conducted to observe the CNV in vitro. Vascular endothelial growth factor (VEGF, matrix metalloproteinase (MMP-2, and MMP-9 expression were measured in retinal and choroidal-scleral lysates 7 days after laser injury. Moreover, the effect of M. officinalis extract on tertiary-butylhydroperoxide (t-BH-induced VEGF secretion and mRNA levels of VEGF, MMP-2, and MMP-9 were evaluated in human retinal epithelial cells (ARPE-19 as well as in human umbilical vein endothelial cells (HUVECs.The CNV thickness in M. officinalis-treated rats was significantly lower than in vehicle-treated rats by histological analysis. The CNV thickness was 33.93±7.64 µm in the high-dose group (P<0.001, 44.09±12.01 µm in the low-dose group (P = 0.016, and 51.00±12.37 µm in the control group. The proportion of CNV lesions with clinically significant fluorescein leakage was 9.2% in rats treated with high-dose M. officinalis, which was significantly lower than in control rats (53.4%, P<0.001. The levels of VEGF, MMP-2, and MMP-9 were significantly lower in the high-dose group than in the control group. Meanwhile, M. officinalis extract suppressed t-BH-induced transcription of VEGF and MMP-9 in ARPE-19 cells and HUVECs.Systemic administration of M. officinalis extract suppressed laser-induced CNV formation in rats. Inhibition of

  7. Bone Marrow Transplantation Transfers Age-Related Susceptibility to Neovascular Remodeling in Murine Laser-Induced Choroidal Neovascularization

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    Espinosa-Heidmann, Diego G.; Malek, Goldis; Mettu, Priyatham S.; Caicedo, Alejandro; Saloupis, Peter; Gach, Sarah; Dunnon, Askia K.; Hu, Peng; Spiga, Maria-Grazia; Cousins, Scott W.

    2013-01-01

    Purpose. Neovascular remodeling (NVR), the progression of small capillaries into large-caliber arterioles with perivascular fibrosis, represents a major therapeutic challenge in neovascular age-related macular degeneration (AMD). Neovascular remodeling occurs after laser-induced choroidal neovascularization (CNV) in aged but not young mice. Additionally, bone marrow–derived cells, including macrophages, endothelial precursor cells, and mesenchymal precursor cells, contribute to CNV severity. In this study, we investigated the impact of aged bone marrow transplantation (BMT) on the degree of fibrosis, size, and vascular morphology of CNV lesions in a mouse model of laser-induced CNV. Methods. Young (2 months) and old (16 months) mice were transplanted with green fluorescent protein (GFP)-labeled bone marrow isolated from either young or old donors. Laser CNV was induced 1 month following transplant, and eyes were analyzed via choroidal flat mounts and immunohistochemistry 1 month postlaser. The identity of cells infiltrating CNV lesions was determined using specific markers for the labeled transplanted cells (GFP+), macrophages (F4/80+), perivascular mesenchymal-derived cells (smooth muscle actin, SMA+), and endothelial cells (CD31+). Results. Bone marrow transplantation from aged mice transferred susceptibility to NVR into young recipients. Inversely, transplantation of young marrow into old mice prevented NVR, preserving small size and minimal fibrosis. Mice with NVR demonstrated a greater relative contribution of marrow-derived SMA+ perivascular mesenchymal cells as compared to other cells. Conclusions. Our findings indicate that the status of bone marrow is an important determining factor of neovascular severity. Furthermore, we find that perivascular mesenchymal cells, rather than endothelial cells, derived from aged bone marrow may contribute to increased CNV severity in this murine model of experimental neovascularization. PMID:24135751

  8. Study of krypton laser-induced choroidal neovascularization in a Guinea pig model of high anisometropia.

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    Wang, Jianghui; Jiang, Wei; Kang, Zefeng; Liang, Lina; Liu, Xiaoman; Tian, Nannan; Zhang, Qing

    2012-06-01

    To investigate the association between high anisometropia and the area of choroidal neovascularization (CNV) induced by krypton laser in guinea pigs and better understand the pathogenesis and prevention of myopic CNV. Nine 3-week old male guinea pigs with anisometropia >6.00D were randomly assigned to three groups according to examination date after laser photocoagulation (7d, 14d and 28d). All animals underwent refraction. The eye with higher myopia was used as the experimental eye, and the other as the control eye. All eyes received repeated multi-wavelength krypton laser photocoagulation treatments (wavelength: 532nm; laser power: 400mW; spot diameter: 50μm; exposure time: 0.1s). Fundus photography and indocyanine green angiography (ICGA) were performed. Afterwards, the animals were sacrificed immediately, and the eyes were enucleated and processed for histopathologic examination and flat mounts. CNV appeared at 7d after laser treatment. The area of CNV peaked at 14d, and decrease in area and the presence of scarring was noted at 28 d. CNV was present in 66.7% of eyes by ICGA at 14 d. CNV could be observed under light microscopy at all three time points. At 14d, flat mount showed the neovascular plexus around the lesion. Semi-quantitative analysis revealed that the area of CNV in treated eyes was greater than that of control eyes. Since the mechanism of CNV in this study resembles that of CNV in pathological myopia, this model can be used to investigate the etiology, pathogenesis and treatment of CNV in pathological myopia.

  9. Topical application of a G-Quartet aptamer targeting nucleolin attenuates choroidal neovascularization in a model of age-related macular degeneration.

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    Leaderer, Derek; Cashman, Siobhan M; Kumar-Singh, Rajendra

    2015-11-01

    Choroidal neovascularization (CNV) associated with the 'wet' form of age related macular degeneration (AMD) is one of the most common causes of central vision loss among the elderly. The 'wet' form of AMD is currently treated by intravitreal delivery of anti-VEGF agents. However, intravitreal injections are associated with complications and long-term inhibition of VEGF leads to macular atrophy. Thus, there is currently an unmet need for the development of therapies for CNV that target molecules other than VEGF. Here, we describe nucleolin as a novel target for the 'wet' form of AMD. Nucleolin was found on the surface of endothelial cells that migrate from the choroid into the subretinal space in the laser-induced model of 'wet' AMD. AS1411 is a previously described G-quartet oligonucleotide that has been shown to bind nucleolin. We found that AS1411 inhibited the formation of tubes by human umbilical vein endothelial cells (HUVECs) by approximately 27.4% in vitro. AS1411 co-localized with the site of laser induced CNV in vivo. Intravitreally injected AS1411 inhibited laser-induced CNV by 37.6% and attenuated infiltration of macrophages by 40.3%. Finally, topical application of AS1411 led to a 43.4% reduction in CNV. Our observations have potential implications for the development of therapies for CNV and specifically for the 'wet' form of AMD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Attenuation of Choroidal Thickness in Patients With Alzheimer Disease: Evidence From an Italian Prospective Study.

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    Trebbastoni, Alessandro; Marcelli, Michela; Mallone, Fabiana; D'Antonio, Fabrizia; Imbriano, Letizia; Campanelli, Alessandra; de Lena, Carlo; Gharbiya, Magda

    2017-01-01

    To compare the 12-month choroidal thickness (CT) change between Alzheimer disease (AD) patients and normal subjects. In this prospective, observational study, 39 patients with a diagnosis of mild to moderate AD and 39 age-matched control subjects were included. All the subjects underwent neuropsychological (Mini Mental State Examination, Alzheimer disease Assessment Scale-Cognitive Subscale, and the Clinical Dementia Rating Scale) and ophthalmological evaluation, including spectral domain optical coherence tomography, at baseline and after 12 months. CT was measured manually using the caliper tool of the optical coherence tomography device. After 12 months, AD patients had a greater reduction of CT than controls (P≤0.05, adjusted for baseline CT, age, sex, axial length, and smoking). CT in patients with AD showed a rate of thinning greater than what could be expected during the natural course of aging.

  11. Choroid Plexus

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    ... of Tumors Astrocytoma Atypical Teratoid Rhaboid Tumor (ATRT) Chondrosarcoma Choroid Plexus Craniopharyngioma Cysts Ependymoma Germ Cell Tumor ... of Tumors Astrocytoma Atypical Teratoid Rhaboid Tumor (ATRT) Chondrosarcoma Choroid Plexus Craniopharyngioma Cysts Ependymoma Germ Cell Tumor ...

  12. Focal Choroidal Excavation.

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    Cebeci, Zafer; Bayraktar, Şerife; Oray, Merih; Kır, Nur

    2016-12-01

    Focal choroidal excavation is a choroidal pit that can be detected by optical coherence tomography. Central serous chorioretinopathy, choroidal neovascularization and polypoidal choroidal vasculopathy are pathologies associated with focal choroidal excavation. In this article, we present the follow-up and treatment outcomes of three eyes of two patients with focal choroidal excavation.

  13. Choroidal excavation in choroidal osteoma complicated by choroidal neovascularization.

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    Pierro, L; Marchese, A; Gagliardi, M; Introini, U; Battaglia Parodi, M; Casalino, G; Bandello, F

    2017-12-01

    PurposeTo describe multimodal imaging features of choroidal osteoma (CO) complicated by choroidal neovascularization (CNV) and focal choroidal excavation (FCE).MethodsPatients presenting with CO and CNV between January and October 2016 were considered for this study. Diagnosis of CO was confirmed by ultrasound examination. All patients underwent multimodal imaging including optical coherence tomography (OCT), swept-source OCT angiography (DRI OCT Triton, Topcon, Inc., Tokyo, Japan) and fluorescein angiography (Spectralis HRA+OCT; Heidelberg Engineering, Heidelberg, Germany).ResultsTwo patients (one with bilateral CO) were included in the study. OCT showed a FCE in two eyes of two patients (one in correspondence of the CNV and the other adjacent to the CNV). OCT-A demonstrated presence of microvascular flow within neovascular network of the CNVs. Decalcification of the tumor was noted in correspondence of one eye with FCE.ConclusionsFCE may be found in eyes with choroidal osteoma and CNV. OCT-A was a valuable tool for detection of CNV complicating choroidal osteoma. Decalcification of choroidal osteoma may represent a common pathogenic pathway for development of FCE and CNV in choroidal osteoma.

  14. CHOROIDAL NEVI WITH FOCAL CHOROIDAL EXCAVATION AND POLYPOIDAL CHOROIDAL NEOVASCULARIZATION.

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    Simhaee, Daniel; Dolz-Marco, Rosa; Freund, K Bailey

    2017-08-10

    To report two cases of choroidal nevi associated with focal choroidal excavation (FCE) and polypoidal choroidal neovascularization (PCN). Report of two patients with choroidal nevi showing FCE and PCN who underwent multimodal imaging including color fundus photography, fluorescein angiography, indocyanine green angiography, fundus autofluorescence, spectral domain optical coherence tomography, swept-source optical coherence tomography, and optical coherence tomography angiography. Two patients presented with choroidal nevi associated with FCE and PCN. In the first case, a 74-year-old woman, the nevus had sharp margins, a deep FCE, surrounding drusen, and subretinal exudation at its inferior edge due to PCN that responded well to intravitreal anti-vascular endothelial growth factor therapy. In the second case, a 64-year-old woman, the nevus had ill-defined margins, a shallow FCE, and angiographic evidence of PCN without associated exudation. There have been several reports showing an association of either choroidal nevi or FCE with PCN. To our knowledge, there have been no previous reports of FCE identified within choroidal nevi, with or without associated PCN. Since, in one of our cases, the FCE was not apparent on clinical examination, the prevalence of FCE within nevi may be underdiagnosed.

  15. Effect of Brimonidine on Retinal and Choroidal Neovascularization in a Mouse Model of Retinopathy of Prematurity and Laser-Treated Rats

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    Kusari, Jyotirmoy; Padillo, Edwin; Zhou, Sheila X.; Bai, Yanyan; Wang, Juanjuan; Song, Zhiming; Zhu, Meili; Le, Yun-Zheng; Gil, Daniel W.

    2011-01-01

    Purpose. To determine whether chronic treatment with brimonidine (BRI) attenuates retinal vascular leakage and neovascularization in neonatal mice after exposure to high oxygen in a mouse model of retinopathy of prematurity (ROP), and choroidal neovascularization (CNV) in rats after laser treatment. Methods. Experimental CNV was induced by laser treatment in Brown Norway (BN) rats. BRI or vehicle (VEH) was administered by osmotic minipumps, and CNV formation was measured 11 days after laser treatment. Oxygen-induced retinopathy was generated in neonatal mice by exposure to 75% oxygen from postnatal day (P)7 to P12. BRI or VEH was administered by gavage, and vitreoretinal vascular endothelial growth factor (VEGF) concentrations and retinal vascular leakage, neovascularization, and vaso-obliteration were measured on P17. Experimental CNV was induced in rabbits by subretinal lipopolysaccharide/fibroblast growth factor-2 injection. Results. Systemic BRI treatment significantly attenuated laser-induced CNV formation in BN rats when initiated 3 days before or within 1 hour after laser treatment. BRI treatment initiated during exposure to high oxygen significantly attenuated vitreoretinal VEGF concentrations, retinal vascular leakage, and retinal neovascularization in P17 mice subjected to oxygen-induced retinopathy. Intravitreal treatment with BRI had no effect on CNV formation in a rabbit model of nonischemic angiogenesis. Conclusions. BRI treatment significantly attenuated vitreoretinal VEGF concentrations, retinal vascular leakage, and retinal and choroidal neovascularization in animal models of ROP and CNV. BRI may inhibit underlying event(s) of ischemia responsible for upregulation of vitreoretinal VEGF and thus reduce vascular leakage and retinal-choroidal neovascularization. PMID:21482645

  16. Choroidal neovascularization secondary to choroidal nevus simulating an inflammatory lesion

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    Samuray Tuncer

    2013-01-01

    Full Text Available Choroidal nevi are the most common benign pigmented lesions of the fundus. Choroidal neovascularization is a rare complication of choroidal nevi. We report herein a young patient managed successfully with intravitreal bevacizumab injections for juxtapapillary choroidal neovascularization secondary to choroidal nevus simulating an inflammatory lesion.

  17. Focal choroidal excavation complicated by choroidal neovascularization.

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    Xu, Haifeng; Zeng, Fanxing; Shi, Depeng; Sun, Xiaolei; Chen, Xiuli; Bai, Yao

    2014-01-01

    To evaluate the clinical findings of focal choroidal excavation (FCE) complicated by choroidal neovascularization (CNV). Retrospective, observational case series. Twelve patients (15 eyes) with FCE and CNV. The medical records of the patients were reviewed. Clinical findings including age, sex, refraction, color photography, fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), and spectral-domain optical coherence tomography (OCT) were analyzed. Fundus fluorescein angiography, ICGA, and OCT findings. The 12 patients included 6 women and 6 men. The mean age was 46.8±13.4 years (range, 26-64 years). One half of the patients were emmetropic, and the others were myopic (-0.5 to -3.0 diopters). All subjects were Chinese. Before CNV development, normal appearance or nonspecific pigment disturbance could be seen around the choroidal excavation. Corresponding to the excavation, window defects were observed by FFA, whereas hypofluorescence was found on ICGA images. Choroidal neovascularization in all eyes was classic as revealed by FFA. The OCT images showed that all eyes had a single choroidal excavation. In 7 of the 15 eyes, the choroidal excavation was located subfoveally, and in the other 8 eyes, it was eccentric. All CNV lesions grew from the bottom or slope of the excavation. Three patients had bilateral involvement. Choroidal neovascularization occurred in both conforming and nonconforming type FCEs, regardless of whether the excavation was shallow or deep, subfoveal or eccentric. All CNV lesions responded well to intravitreal injection of anti-vascular endothelial growth factor (VEGF) agents. After a single injection, CNV regressed in 13 of 15 eyes. Two eyes received an additional injection. Nonconforming FCE changed to the conforming type after successful treatment of CNV. Focal choroidal excavation is not always stable. Choroidal neovascularization commonly can be seen in patients with FCE and responds well to intravitreal anti-VEGF agents

  18. FOCAL CHOROIDAL EXCAVATION AND CHOROIDAL NEOVASCULARIZATION WITH ASSOCIATED PACHYCHOROID.

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    Ghadiali, Quraish; Dansingani, Kunal K; Freund, K Bailey

    2016-01-01

    To report a case of focal choroidal excavation and choroidal neovascularization in the setting of pachychoroid disease. Multimodal imaging, including fundus photography, fundus autofluorescence, enhanced depth imaging optical coherence tomography, indocyanine green angiography, and en face structural and angiographic optical coherence tomography. The authors describe a 39-year-old female with moderately high myopia presenting with focal choroidal excavation and associated choroidal neovascularization. Multimodal imaging demonstrated pachychoroid features with dilated choroidal vessels surrounding the lesion. Optical coherence tomography angiography showed Type 2 neovascularization. Some cases of focal choroidal excavation and associated neovascularization may be related to structural abnormalities of the associated choroidal vasculature.

  19. Laser-induced tether & spouts

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    Delville, Jean-Pierre

    2004-03-01

    Since the seminal work of Ashkin and Dziedzic on the deformation of transparent free-surfaces induced by laser waves, the optical radiation pressure has been recognized as very appealing to locally manipulate liquid interfaces. While the first developments essentially exploited the interface bending for optical applications in adaptive lensing, radiation pressure effects have recently received renewed interest in connection with nano/bio-technologies, as a non-intrusive tool to probe microscopic surface properties of soft materials including cell stretching, or membrane and interface visco-elasticity. However, as the optical bending of a fluid interface is generally weak, these experiments were essentially limited to the linear regime in deformation. Non-linear behaviors can nevertheless be investigated using very soft transparent liquid interfaces to enhance light effects. At large optical excitation, either a large stable tether is formed, or else a break-up of the interface occurs, depending on the direction of the beam propagation. Physically, the reason for this asymmetry can be traced to whether total reflection of light at deformed interface occurs or not. Laser-induced interface instability leads to the formation of a stationary beam-centered liquid micro-jet emitting droplets, which anticipates the bases for new applications in micro-fluidics and liquid micro-spraying. On the other hand, the method can be extended to form microscopic liquid bridges of very large aspect ratio, because optical forces are able to overcome the fundamental Rayleigh-Plateau limitation. As laser-induced micro-jets, laser-sustained liquid columns are tunable in aspect ratio and adjustable in direction. Consequently, the applications range of "opto-hydrodynamic" interface instability is wide, going from micro-optics (i.e. liquid columns also behave as soft optical fibers) to micro-fluidics, as fluid transfer can be optically monitored and directed in three dimensions.

  20. Laser-induced damage in optical materials

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    Ristau, Detlev

    2014-01-01

    Dedicated to users and developers of high-powered systems, Laser-Induced Damage in Optical Materials focuses on the research field of laser-induced damage and explores the significant and steady growth of applications for high-power lasers in the academic, industrial, and military arenas. Written by renowned experts in the field, this book concentrates on the major topics of laser-induced damage in optical materials and most specifically addresses research in laser damage that occurs in the bulk and on the surface or the coating of optical components. It considers key issues in the field of hi

  1. Vitelliform focal choroidal excavation.

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    Or, Chris; Forooghian, Farzin

    2014-05-30

    Focal choroidal excavations (FCE) are characterized by foveal or perifoveal choroid excavations seen on optical coherence tomography (OCT). The authors report a case of FCE associated with a vitelliform lesion within the excavation. A case of FCE associated with a small vitelliform lesion has been described previously, but the larger extent of the vitelliform lesion observed in the current case has not been previously reported. This may represent a novel category of FCE, vitelliform focal choroidal excavation, in which deposition of vitelliform material is associated with its development. Copyright 2014, SLACK Incorporated.

  2. Noninvasive thermography of laser-induced hyperthermia using magnetic resonance

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    Maswadi, Saher M.; Glickman, Randolph D.; Dodd, Stephen J.; Gao, Jia Hong

    2004-07-01

    The possibility to induce selective hyperthermia in a target tissue or organ is of great interest for the treatment of cancer and other diseases. An emerging application of thermotherapy is for choroidal neovascularization, a complication of age-related macular degeneration. The therapy is currently limited because the temperature required for optimal tissue response is unknown. We report here an investigation of near infrared laser-induced heating in an ocular phantom. Magnetic resonance thermography (MRT) was used as a non-invasive method to determine the temperature distribution inside the phantom during exposure to a continuous wave diode laser at 806 nm wavelength with 1 watt maximum output. The laser beam had a quasi-gaussian profile, with a radius of 0.8-2.4 mm at target. High quality temperature images were obtained from temperature-dependent phase shifts in the proton resonance frequency with a resolution of 1deg C or better, using a 2T magnet. A phantom with a layer of bovine RPE melanin of 1.5 mm thickness was used to determine the spatial resolution of the MRT measurements. Three dimensional temperature maps were also constructed showing a spatial resolution of 0.25 mm in all direction. The heat distribution depended on the laser parameters, as well as the orientation of the melanin layer with respect to the incident laser beam. The temperature profiles determined by MRT closely followed predictions of a heat diffusion model, based on the optical properties of infrared light in melanin. These results support the use of MRT to optimize laser-induced hyperthermia in a small organ such as the eye.

  3. Choroidal neovascularization associated with focal choroidal excavation.

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    Lee, Jae Hyung; Lee, Won Ki

    2014-03-01

    To describe the clinical and imaging characteristics of choroidal neovascularization (CNV) accompanied by focal choroidal excavation. Retrospective, interventional case series. The medical records of 16 patients (16 eyes) were reviewed. Imaging findings including fluorescein angiography (FA), indocyanine green angiography, and spectral-domain optical coherence tomography (SD OCT) were analyzed. CNV complexes were primarily located beneath the retinal pigment epithelium (type 1 CNV) in 9 eyes and in the subneurosensory retinal space (type 2 CNV) in 7 eyes, as assessed by SD OCT. Seven of 8 patients over 50 years old had type 1 CNV, and 6 of 8 patients under 50 had type 2 lesions. All 7 eyes with type 2 CNV exhibited classic CNV on FA. Additionally, 7 of 9 eyes with type 1 CNV had the classic pattern, and in these eyes, the CNV complexes were confined to the concavity of choroidal excavation. In 15 patients treated by anti-vascular endothelial growth factor (anti-VEGF) injections, the mean best-corrected visual acuity improved from 20/44 to 20/26 with a mean of 3.7 injections during a mean follow-up period of 14.5 months. The CNV growth pattern and extent seem to be determined by the degree of damage to the retinal pigment epithelium/Bruch membrane complex resulting from choroidal excavation, as well as age. Neovascular complexes tend to be located within the boundary of choroidal excavation and are revealed as classic patterns on FA, even in type 1 CNV. Anti-VEGF was notably effective for treating these lesions, with a low rate of recurrence. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Quantitative laser-induced fluorescence measurements of nitric oxide in a heavy-duty Diesel engine

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    Verbiezen, K.; Klein-Douwel, R. J. H.; van Viet, A. P.; Donkerbroek, A. J.; Meerts, W. L.; Dam, N. J.; ter Meulen, J. J.

    2007-01-01

    We present quantitative, in-cylinder, UV-laser-induced fluorescence measurements of nitric oxide in a heavy-duty Diesel engine. Processing of the raw fluorescence signals includes a detailed correction, based on additional measurements, for the effect of laser beam and fluorescence attenuation, and

  5. Lactoferrin Reduces Chorioretinal Damage in the Murine Laser Model of Choroidal Neovascularization.

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    Montezuma, Sandra R; Dolezal, Luke D; Rageh, Abrar A; Mar, Kevin; Jordan, Michael; Ferrington, Deborah A

    2015-09-01

    To determine whether lactoferrin, specifically endogenous mouse lactoferrin and exogenous intraperitoneal lactoferrin treatment, plays a role in reducing the chorioretinal damage in the laser-induced model of choroidal neovascularization. Four 532-nm argon laser spots were placed between the retinal vessels of each eye. At Day 7, Fluorescein Angiography was performed to grade the lesions. The mice were perfused with fluorescein-labeled tomato lectin and sacrificed. The retinal pigment epithelium-choroid-sclera complex was flat-mounted and analyzed with a confocal microscope to measure the volume of the lesions. The effect of endogenous lactoferrin was studied by comparing lactoferrin knockout and wild-type (WT) mice. The effect of exogenous lactoferrin treatment was studied by comparing lactoferrin knockout and WT mice treated with lactoferrin for seven days to their respective controls. Lactoferrin knockout mice demonstrated 47% larger lesion volumes than WT mice (p Lactoferrin reduced the lesion volume in Lactoferrin knockout mice by 26% (p lactoferrin knockout mice compared with control WT mice (16% versus 5%). Intraperitoneal treatment with Lactoferrin reduced the grade 2B lesions from 16% to 2% in Lactoferrin knockout mice. The endogenous lactoferrin present in WT mice appears to reduce the choroidal neovascularization in the laser-induced choroidal neovascularization model in mice. Treatment with exogenous lactoferrin is capable of reducing the choroidal neovascularization in lactoferrin knockout mice but does not add a significant protective effect to WT.

  6. [Laser-induced Maculopathy Caused by Strangers].

    Science.gov (United States)

    Hohberger, B; Bergua, A

    2016-10-01

    Background: Laser-induced ocular injuries are of public interest, especially when caused by strangers. Clinical signs and follow-up: Two laser-induced maculopathies were presented which had been caused by strangers. Morphological findings were shown by funduscopy and Spectralis Domain OCT follow-up. Conclusion: Severe retina injuries can be induced by laser pointers of higher classes. Georg Thieme Verlag KG Stuttgart · New York.

  7. High-dose methylprednisolone treatment of laser-induced retinal injury exacerbates acute inflammation and long-term scarring

    Science.gov (United States)

    Schuschereba, Steven T.; Cross, Michael E.; Scales, David K.; Pizarro, Jose M.; Edsall, Peter R.; Stuck, Bruce E.; Marshall, John

    1999-06-01

    Purpose. To evaluate therapeutics for attenuating retinal laser injury. Methods. New Zealand Red rabbits (n=76) were pretreated (IV) with either a single dose of hydroxyethyl starch conjugated deferoxamine (HES-DFO, n=29) (6.1 ml/kg, 16.4 mg/ml) or methylprednisolone sodium succinate (MP, n=22) (30 mg/kg, followed by taper of 30, 20, 20, and 10 mg/kg/day for a total of 5d). Controls were untreated (n=25). Fifteen min later, animals were irradiated with a multiline cw argon laser (285 mW, 10 msec pulse durations, 16 lesions/eye). Funduscopy, fluorescein angiography, histology, and morphometry were performed at 10 min, 1h, 3h, 24h, 1 mo, and 6 mo after irradiation. Leukocytes were counted at lesion centers for retinal and choroidal compartments at 1, 3, and 24h. Results. At 3h, percent area incrase for the lesions was highest for MP (44%) and lowest for HES-DFO (16%)(p<0.05). In hemorrhagic lesions, MP treatment resulted in the highest increase of retinal neotrophils by 24h (p<0.05), and by 1 and 6 mo extensive chorio-retinal scarring occurred in nonhemorrhagic and hemorrhagic lesions. Also, no benefit was demonstrated on sparing of photoreceptors with MP treatment. Conclusions. Treatment of laser-induced retinal injury with methylprednisolone (MP) exacerbates acute inflammation and long-term chorio-retinal scarring; however, hydroxyethyl starch conjugated deferoxamine therapy ameliorates these aspects of injury. Data suggest caution in the use of MP therapy for laser injuries.

  8. Circumscribed choroidal hemangioma

    Directory of Open Access Journals (Sweden)

    Saeed Karimi

    2015-01-01

    Full Text Available Circumscribed choroidal hemangiomas are benign vascular hamartomas without systemic associations. Generally, they are orange-red elevated masses, which are found posterior to the equator. Lesions are usually solitary and unilateral. Overlying subretinal fluid, serous retinal detachment and cystoid macular edema are common findings. Intravenous fluorescein angiography, indocyanine green angiography, ultrasonography, optical coherence tomography and enhanced depth imaging are helpful ancillary tests for diagnosis of circumscribed choroidal hemangiomas. Asymptomatic circumscribed choroidal hemangiomas do not require treatment. For symptomatic lesions with exudative retinal detachment or cystoid macular edema, photodynamic therapy has emerged as the treatment of choice with high rates of tumor regression, subretinal fluid resorption and minimal complications. Lens-sparing external beam radiotherapy, plaque brachytherapy, proton beam therapy, stereotactic radiosurgery, transpupillary thermotherapy, laser photocoagulation and anti-VEGF injections are other treatment modalities.

  9. Transvitreal retino-choroidal biopsy of suspected malignant lesions of the choroid

    DEFF Research Database (Denmark)

    Jensen, O.A.; Prause, J.U.; Scherfig, E.

    1997-01-01

    ophthalmology, intraocular biopsy, transvitreal retino-choroidal biopsy, malignant melanoma of choroid, histopathology, brachytherapy......ophthalmology, intraocular biopsy, transvitreal retino-choroidal biopsy, malignant melanoma of choroid, histopathology, brachytherapy...

  10. Inhibition of APE1/Ref-1 redox activity rescues human retinal pigment epithelial cells from oxidative stress and reduces choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Y. Li

    2014-01-01

    Full Text Available The effectiveness of current treatment for age related macular degeneration (AMD by targeting one molecule is limited due to its multifactorial nature and heterogeneous pathologies. Treatment strategy to target multiple signaling pathways or pathological components in AMD pathogenesis is under investigation for better clinical outcome. Inhibition of the redox function of apurinic endonuclease 1/redox factor-1 (APE1 was found to suppress endothelial angiogenesis and promote neuronal cell recovery, thereby may serve as a potential treatment for AMD. In the current study, we for the first time have found that a specific inhibitor of APE1 redox function by a small molecule compound E3330 regulates retinal pigment epithelium (RPEs cell response to oxidative stress. E3330 significantly blocked sub-lethal doses of oxidized low density lipoprotein (oxLDL induced proliferation decline and senescence advancement of RPEs. At the same time, E3330 remarkably decreased the accumulation of intracellular reactive oxygen species (ROS and down-regulated the productions of monocyte chemoattractant protein-1 (MCP-1 and vascular endothelial growth factor (VEGF, as well as attenuated the level of nuclear factor-κB (NF-κB p65 in RPEs. A panel of stress and toxicity responsive transcription factors that were significantly upregulated by oxLDL was restored by E3330, including Nrf2/Nrf1, p53, NF-κB, HIF1, CBF/NF-Y/YY1, and MTF-1. Further, a single intravitreal injection of E3330 effectively reduced the progression of laser-induced choroidal neovascularization (CNV in mouse eyes. These data revealed that E3330 effectively rescued RPEs from oxidative stress induced senescence and dysfunctions in multiple aspects in vitro, and attenuated laser-induced damages to RPE–Bruch׳s membrane complex in vivo. Together with its previously established anti-angiogenic and neuroprotection benefits, E3330 is implicated for potential use for AMD treatment.

  11. Radiotherapy of choroidal metastases

    Energy Technology Data Exchange (ETDEWEB)

    Hoogenhout, J.; Gasteren, J.J.M. van; Brink, H.M.A.; Verbeek, A.M.; Beex, L.V.A.M.

    1989-05-01

    With binocular indirect ophthalmoscopy, fluorescin angiography and ultrasonography 68 choroidal metastases in 52 eyes of 39 patients were diagnosed. The primary tumors were mainly breast cancer (81%) and lung cancer (10%). After radiation treatment the visual acuity improved in 17 eyes (38%), stabilized in 15 eyes (33%), whereas in 13 eyes (29%) deterioration could not be prevented (seven eyes unknown). Regression of the lesions or its accompanying secondary retinal detachment was seen in 78% of the eyes treated. Acute transient side effects of radiation therapy were keratoconjunctivitis (nine patients) and acute glaucoma in one patient. No cataractous changes of the lens were observed in the post radiation period (one to 42 months). Irradiation of choroidal metastases can contribute to improvement of the quality of life with a treatment scheme of 30 Gy in ten daily fractions.

  12. Laser induced breakdown spectroscopy on meteorites

    Energy Technology Data Exchange (ETDEWEB)

    De Giacomo, A. [Department of Chemistry, University of Bari (Italy); MIP-CNR sec Bari (Italy)], E-mail: alessandro.degiacomo@ba.imip.cnr.it; Dell' Aglio, M.; De Pascale, O. [MIP-CNR sec Bari (Italy); Longo, S.; Capitelli, M. [Department of Chemistry, University of Bari (Italy); MIP-CNR sec Bari (Italy)

    2007-12-15

    The classification of meteorites when geological analysis is unfeasible is generally made by the spectral line emission ratio of some characteristic elements. Indeed when a meteorite impacts Earth's atmosphere, hot plasma is generated, as a consequence of the braking effect of air, with the consequent ablation of the falling body. Usually, by the plasma emission spectrum, the meteorite composition is determined, assuming the Boltzmann equilibrium. The plasma generated during Laser Induced Breakdown Spectroscopy (LIBS) experiment shows similar characteristics and allows one to verify the mentioned method with higher accuracy. On the other hand the study of Laser Induced Breakdown Spectroscopy on meteorite can be useful for both improving meteorite classification methods and developing on-flight techniques for asteroid investigation. In this paper certified meteorites belonging to different typologies have been investigated by LIBS: Dofhar 461 (lunar meteorite), Chondrite L6 (stony meteorite), Dofhar 019 (Mars meteorite) and Sikhote Alin (irony meteorite)

  13. In vivo gene transfer into choroidal neovascularization by the HVJ liposome method.

    Science.gov (United States)

    Otsuji, T; Ogata, N; Takahashi, K; Matsushima, M; Uyama, M; Kaneda, Y

    2000-02-01

    To evaluate the efficacy of the HVJ liposome method for gene transfer in rats with experimentally induced choroidal neovascularization. Plasmid DNA containing the LacZ reporter gene, or fluorescein isothiocyanate (FITC)-labeled double-stranded phosphorothioate oligodeoxynucleotides (S-ODNs), was encapsulated in liposomes. The liposomes were coated with the envelope of inactivated hemagglutinating virus of Japan (HVJ). Intense laser burns were applied to the posterior pole of the retina of pigmented rats to induce choroidal neovascularization. Following photocoagulation, HVJ liposome suspension was injected into the vitreous. On days 3, 7, 14, and 28 after injection, the eyes were removed and fixed. The eyes injected with LacZ gene were reacted with X-gal, frozen, and cut into thin sections. The sections were examined for the expression of the LacZ gene by light microscopy. The enucleated eyes injected with double-stranded S-ODNs were frozen, cut into thin sections, and examined a confocal scanning laser microscope for FITC labeling. Eyes without injection of HVJ liposomes served as controls. Expression of LacZ genes (beta-galactosidase activity), or localization of FITC labeling, was observed mainly in the laser-induced choroidal neovascular tissue from 3 to 28 days after the intravitreal injection of HVJ liposome. We conclude that the HVJ liposome method achieved effective gene transfer into choroidal neovascular tissue. Thus, this method can be used as a nonviral gene therapy system for the treatment of choroidal neovascularization in vivo.

  14. [Image characters of optical coherence tomography in laser-induced maculopathy].

    Science.gov (United States)

    Xiao, Hui; Liu, Xing; Huang, Jingjing; Mao, Zheng; Li, Mei; Cao, Dan

    2010-11-01

    To observe the changes of ocular fundus and to describe the image features of optical coherence tomography (OCT) in patients with laser-induced maculopathy. Four patients (4 eyes) with decreased visual acuity due to laser injury were recruited into the study between April 2002 to December 2009. All patients underwent routine check-up for eyes. The four cases presented with different clinical characteristics from each another. In the first case, OCT showed lamella macular hole, with partially remained outer sensory retina. The signals of inner segments/outer segments (IS/OS) band and RPE band were disrupted. The choroidal band was distorted with increased reflection. Perimacular epiretinal membrane and vitreous hemorrhage were also observed. The second case had a full-thickness macular hole with retina edema surrounding the hole. The third case presented local serous sensory retinal detachment in macula. The fourth case presented hyper-reflection of the inner retina in macula which indicated hemorrhage. There are various patterns of laser-induced maculopathy. OCT is a useful noninvasive diagnostic tool to delineate the layer, extent and configuration of the damage on retina.

  15. Laser induced forward transfer of soft materials

    Science.gov (United States)

    Palla-Papavlu, A.; Dinca, V.; Luculescu, C.; Shaw-Stewart, J.; Nagel, M.; Lippert, T.; Dinescu, M.

    2010-12-01

    A strong research effort is presently aimed at patterning methodologies for obtaining controlled defined micrometric polymeric structures for a wide range of applications, including electronics, optoelectronics, sensors, medicine etc. Lasers have been identified as appropriate tools for processing of different materials, such as ceramics and metals, but also for soft, easily damageable materials (biological compounds and polymers). In this work we study the dynamics of laser induced forward transfer (LIFT) with a gap between the donor and the receiver substrates, which is the basis for possible applications that require multilayer depositions with high spatial resolution.

  16. Laser induced fluorescence of trapped molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Grieman, F.J.

    1979-10-01

    An experimental apparatus for obtaining the optical spectra of molecular ions is described. The experimental technique includes the use of three dimensional ion trapping, laser induced fluorescence, and gated photon counting methods. The ions, which are produced by electron impact, are confined in a radio-frequency quadrupole ion trap of cylindrical design. Because the quadrupole ion trap allows mass selection of the molecular ion desired for study, the analysis of the spectra obtained is greatly simplified. The ion trap also confines the ions to a region easily probed by a laser beam. 18 references.

  17. FGF21 Administration Suppresses Retinal and Choroidal Neovascularization in Mice

    Directory of Open Access Journals (Sweden)

    Zhongjie Fu

    2017-02-01

    Full Text Available Pathological neovascularization, a leading cause of blindness, is seen in retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration. Using a mouse model of hypoxia-driven retinal neovascularization, we find that fibroblast growth factor 21 (FGF21 administration suppresses, and FGF21 deficiency worsens, retinal neovessel growth. The protective effect of FGF21 against neovessel growth was abolished in adiponectin (APN-deficient mice. FGF21 administration also decreased neovascular lesions in two models of neovascular age-related macular degeneration: very-low-density lipoprotein-receptor-deficient mice with retinal angiomatous proliferation and laser-induced choroidal neovascularization. FGF21 inhibited tumor necrosis α (TNF-α expression but did not alter Vegfa expression in neovascular eyes. These data suggest that FGF21 may be a therapeutic target for pathologic vessel growth in patients with neovascular eye diseases, including retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration.

  18. Optodynamic characterization of shock waves after laser-induced breakdown in water.

    Science.gov (United States)

    Petkovsek, Rok; Mozina, Janez; Mocnik, Grisa

    2005-05-30

    Plasma and a cavitation bubble develop at the site of laser-induced breakdown in water. Their formation and the propagation of the shock wave were monitored by a beam-deflection probe and an arm-compensated interferometer. The interferometer part of the setup was used to determine the relative position of the laser-induced breakdown. The time-of-flight data from the breakdown site to the probe beam yielded the velocity, and from the velocity the shock-wave pressure amplitudes were calculated. Two regions were found where the pressure decays with different exponents, pointing to a strong attenuation mechanism in the initial phase of the shock-wave propagation.

  19. Choroidal neovascular membrane associated with choroidal osteoma (CO treated with trans-pupillary thermo therapy.

    Directory of Open Access Journals (Sweden)

    Sharma Sumita

    2004-01-01

    Full Text Available Choroidal neovascular membrane, a known complication of choroidal osteoma causing visual loss when located subfoveally, can be successfully treated with transpupillary thermo therapy.

  20. Expulsive choroidal haemorrhage

    Directory of Open Access Journals (Sweden)

    Srinivasan M

    1992-01-01

    Full Text Available Expulsive choroidal haemorrhage is a dramatic and serious complication of cataract surgery that occurred in five patients out of ten thousand consecutive cataract surgeries performed by the author during the year 1989 and 1990. Report about this dreaded complication after cataract surgery are scanty and as far as I can remember I have not seen any report in Indian ophthalmic literature recently. Since cataract surgery forms the major part of intra ocular surgeries performed in our country, I thought it would be appropriate to report about this rare complication which may occur to all of us. Out of five cases 3 were males and 2 were females in the age group ranging between 45-72 years. Two eyes regained vision up to 6/12 after intra operative expulsive haemorrhage. All the eyes were salvaged by doing anterior sclerotomy. Diabetes, hypertension, glaucoma and myopia are the commonest predisposing factors.

  1. Laser-Induced Damage with Femtosecond Pulses

    Science.gov (United States)

    Kafka, Kyle R. P.

    The strong electric fields of focused femtosecond laser pulses lead to non-equilibrium dynamics in materials, which, beyond a threshold intensity, causes laser-induced damage (LID). Such a strongly non-linear and non-perturbative process renders important LID observables like fluence and intensity thresholds and damage morphology (crater) extremely difficult to predict quantitatively. However, femtosecond LID carries a high degree of precision, which has been exploited in various micro/nano-machining and surface engineering applications, such as human eye surgery and super-hydrophobic surfaces. This dissertation presents an array of experimental studies which have measured the damage behavior of various materials under femtosecond irradiation. Precision experiments were performed to produce extreme spatio-temporal confinement of the femtosecond laser-solid damage interaction on monocrystalline Cu, which made possible the first successful direct-benchmarking of LID simulation with realistic damage craters. A technique was developed to produce laser-induced periodic surface structures (LIPSS) in a single pulse (typically a multi-pulse phenomenon), and was used to perform a pump-probe study which revealed asynchronous LIPSS formation on copper. Combined with 1-D calculations, this new experimental result suggests more drastic electron heating than expected. Few-cycle pulses were used to study the LID performance and morphology of commercial ultra-broadband optics, which had not been systematically studied before. With extensive surface analysis, various morphologies were observed, including LIPSS, swelling (blisters), simple craters, and even ring-shaped structures, which varied depending on the coating design, number of pulses, and air/vacuum test environment. Mechanisms leading to these morphologies are discussed, many of which are ultrafast in nature. The applied damage behavior of multi-layer dielectric mirrors was measured and compared between long pulse (150 ps

  2. Choroidal changes after cardiopulmonary bypass.

    Science.gov (United States)

    Pekel, G; Alur, I; Alihanoglu, Y I; Yagci, R; Emrecan, B

    2014-11-01

    Choroid, which is the vascular tissue responsible for blood supply to the outer parts of the retina, might be affected by hemodynamic events. We aimed to reveal choroidal thickness and ocular pulse amplitude changes after cardiopulmonary bypass in which gross hemodynamic alterations occur. Forty-two eyes of 42 patients who underwent heart surgery with cardiopulmonary bypass were examined in this prospective, cross-sectional case series. The spectral domain optical coherence tomography (Spectralis, Heidelberg, Germany) was used to analyze sub-foveal choroidal thickness. The ocular pulse amplitude, the surrogate of gross choroidal blood flow, was measured with the Pascal dynamic contour tonometer (Pascal DCT, Swiss Microtechnology AG, Port, Switzerland).. The intraocular pressure was also measured with this tonometer. The examinations were performed pre-operatively and post-operatively at the first week and first month. The mean age of the patients was 58.8 ± 12.4 years. The mean sub-foveal choroidal thickness and ocular pulse amplitude values did not change statistically significantly after the operations at the follow-up visits (p>0.05). Also, there were no important correlations between cardiopulmonary bypass time and mean sub-foveal choroidal thickness and ocular pulse amplitude changes at the post-operative first week (p>0.05). The intraocular pressure values were decreased markedly at the control visits (pcardiopulmonary bypass. © The Author(s) 2014.

  3. CW CO2 Laser Induced Chemical Reactions

    Science.gov (United States)

    Pola, Joseph

    1989-05-01

    CW CO2 laser driven reactions between sulfur hexafluoride and carbon oxide, carbon suboxide, carbonyl sulfide and carbon disulfide proceed at subatmospheric pressures and yield fluorinated carbon compounds and sulfur tetrafluoride. CW CO2 laser driven reactions of organic compounds in the presence of energy-conveying sulfur hexafluoride show reaction course different from that normally observed due to elimination of reactor hot surface effects. The examples concern the decomposition of polychlorohydrocarbons, 2-nitropropane, tert.-butylamine, allyl chloride, spirohexane, isobornyl acetate and the oxidation of haloolefins. CW CO2 laser induced fragmentation of 1-methyl-l-silacyclobutanes and 4-silaspiro(3.4)octane in the presence of sulfur hexafluoride is an effective way for preparation and deposition of stable organosilicon polymers.

  4. Coverage threshold for laser-induced lithography

    Science.gov (United States)

    Martins, Weliton S.; Oriá, Marcos; Passerat de Silans, Thierry; Chevrollier, Martine

    2017-05-01

    Recent experimental observations of laser-induced adsorption at the interface between an alkali vapor and a dielectric surface have demonstrated the possibility of growing metallic films of nanometric thickness on dielectric surfaces, with arbitrary shapes determined by the intensity profile of the light. The mechanisms directly responsible for the accumulation of atoms at the irradiated surface have been shown to involve photo-ionization of atoms very close to the surface. However, the existence of a vapor-pressure threshold for initiating the film growth still raises questions on the processes occurring at the surface. In this letter, we report on the observation that the vapor-pressure threshold corresponds to a minimum adatom coverage necessary for the surface to effectively neutralize the incoming ions and make possible the growth of a multilayer film. We discuss the hypothesis that the coverage threshold is a surface conductivity threshold.

  5. Laser induced fluorescence of dental caries

    Science.gov (United States)

    Albin, S.; Byvik, C. E.; Buoncristiani, A. M.

    1988-01-01

    Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

  6. Choroidal excavation with polypoidal choroidal vasculopathy: a case report

    Directory of Open Access Journals (Sweden)

    Kobayashi W

    2012-08-01

    Full Text Available Wataru Kobayashi,1 Toshiaki Abe,2 Hiroshi Tamai,1 Toru Nakazawa11Department of Ophthalmology, 2Division of Clinical Cell Therapy, Center for Advanced Medical Research and Development (ART, Tohoku University Graduate School of Medical Science, Sendai, JapanPurpose: This is a report of a case of choroidal excavation accompanied by polypoidal choroidal vasculopathy (PCV and retinal pigment epithelium detachment (PED.Methods: A 57-year-old Japanese woman who had begun complaining of metamorphopsia in her left eye 7 months earlier underwent spectral-domain optical coherence tomography (SD-OCT, fluorescein angiography (FA, and indocyanine green angiography (IA, as well as a routine ophthalmological examination.Results: The patient’s intraocular pressure, visual acuity, and visual field were within normal range. Ophthalmoscopy revealed a serous macular detachment, soft drusen, exudates, and a reddish-orange elevated lesion in the macula of the left eye. The right eye was normal. SD-OCT revealed two lesions in the left eye. One was a PED accompanied by a notch sign, and the other was a choroidal excavation. Additionally, FA revealed a window defect in the PED, and IA showed typical PCV. Three monthly injections of antivascular endothelial growth factor preserved visual acuity, but failed to have any visible effect on the lesion during the 6-month follow up period.Conclusions: This is the first report of choroidal excavation accompanied by PED and PCV. The data suggest that choroidal excavation may be associated with various changes that have not been previously reported. Careful observation of such cases may therefore be necessary.Keywords: choroidal excavation, polypoidal choroidal vasculopathy, anti-vascular endothelial growth factor treatment

  7. Laser-induced inactivation of Plasmodium falciparum.

    Science.gov (United States)

    LeBlanc, Danielle; Story, Robert; Gross, Eitan

    2012-08-08

    Haemozoin crystals, produced by Plasmodium during its intra-erythrocytic asexual reproduction cycle, can generate UV light via the laser-induced, non-linear optical process of third harmonic generation (THG). In the current study the feasibility of using haemozoin, constitutively stored in the parasite's food vacuole, to kill the parasite by irradiation with a near IR laser was evaluated. Cultured Plasmodium parasites at different stages of development were irradiated with a pulsed NIR laser and the viability of parasites at each stage was evaluated from their corresponding growth curves using the continuous culture method. Additional testing for germicidal effects of haemozoin and NIR laser was performed by adding synthetic haemozoin crystals to Escherichia coli in suspension. Cell suspensions were then irradiated with the laser and small aliquots taken and spread on agar plates containing selective agents to determine cell viability (CFU). Parasites in the late-trophozoites form as well as trophozoites in early-stage of DNA synthesis were found to be the most sensitive to the treatment with -4-log reduction in viability after six passes through the laser beam; followed by parasites in ring phase (-2-log reduction). A -1-log reduction in E. coli viability was obtained following a 60 min irradiation regimen of the bacteria in the presence of 1 μM synthetic haemozoin and a -2-log reduction in the presence of 10 μM haemozoin. Minimal (≤ 15%) cell kill was observed in the presence of 10 μM haemin. Laser-induced third-harmonic generation by haemozoin can be used to inactivate Plasmodium. This result may have clinical implications for treating severe malaria symptoms by irradiating the patient's blood through the skin or through dialysis tubing with a NIR laser.

  8. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jwad, Tahseen, E-mail: taj355@bham.ac.uk; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-30

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  9. Laser-induced inactivation of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    LeBlanc Danielle

    2012-08-01

    Full Text Available Abstract Background Haemozoin crystals, produced by Plasmodium during its intra-erythrocytic asexual reproduction cycle, can generate UV light via the laser-induced, non-linear optical process of third harmonic generation (THG. In the current study the feasibility of using haemozoin, constitutively stored in the parasite’s food vacuole, to kill the parasite by irradiation with a near IR laser was evaluated. Methods Cultured Plasmodium parasites at different stages of development were irradiated with a pulsed NIR laser and the viability of parasites at each stage was evaluated from their corresponding growth curves using the continuous culture method. Additional testing for germicidal effects of haemozoin and NIR laser was performed by adding synthetic haemozoin crystals to Escherichia coli in suspension. Cell suspensions were then irradiated with the laser and small aliquots taken and spread on agar plates containing selective agents to determine cell viability (CFU. Results Parasites in the late-trophozoites form as well as trophozoites in early-stage of DNA synthesis were found to be the most sensitive to the treatment with ~4-log reduction in viability after six passes through the laser beam; followed by parasites in ring phase (~2-log reduction. A ~1-log reduction in E. coli viability was obtained following a 60 min irradiation regimen of the bacteria in the presence of 1 μM synthetic haemozoin and a ~2-log reduction in the presence of 10 μM haemozoin. Minimal (≤15% cell kill was observed in the presence of 10 μM haemin. Conclusions Laser-induced third-harmonic generation by haemozoin can be used to inactivate Plasmodium. This result may have clinical implications for treating severe malaria symptoms by irradiating the patient’s blood through the skin or through dialysis tubing with a NIR laser.

  10. Choroidal excavation with polypoidal choroidal vasculopathy: a case report.

    Science.gov (United States)

    Kobayashi, Wataru; Abe, Toshiaki; Tamai, Hiroshi; Nakazawa, Toru

    2012-01-01

    This is a report of a case of choroidal excavation accompanied by polypoidal choroidal vasculopathy (PCV) and retinal pigment epithelium detachment (PED). A 57-year-old Japanese woman who had begun complaining of metamorphopsia in her left eye 7 months earlier underwent spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography (FA), and indocyanine green angiography (IA), as well as a routine ophthalmological examination. The patient's intraocular pressure, visual acuity, and visual field were within normal range. Ophthalmoscopy revealed a serous macular detachment, soft drusen, exudates, and a reddish-orange elevated lesion in the macula of the left eye. The right eye was normal. SD-OCT revealed two lesions in the left eye. One was a PED accompanied by a notch sign, and the other was a choroidal excavation. Additionally, FA revealed a window defect in the PED, and IA showed typical PCV. Three monthly injections of antivascular endothelial growth factor preserved visual acuity, but failed to have any visible effect on the lesion during the 6-month follow up period. This is the first report of choroidal excavation accompanied by PED and PCV. The data suggest that choroidal excavation may be associated with various changes that have not been previously reported. Careful observation of such cases may therefore be necessary.

  11. CLINICAL COURSE OF INFLAMMATORY CHOROIDAL NEOVASCULARIZATION ASSOCIATED WITH FOCAL CHOROIDAL EXCAVATION.

    Science.gov (United States)

    Corbelli, Eleonora; Sacconi, Riccardo; Querques, Lea; Carnevali, Adriano; Giuffrè, Chiara; Rabiolo, Alessandro; Bandello, Francesco; Querques, Giuseppe

    2017-10-23

    To report the clinical course of focal choroidal excavation associated with choroidal neovascularization in a case of choroidal inflammation. Case report. A 41-year-old man presented with blurred vision and metamorphopsia in his left eye. Multimodal imaging including optical coherence tomography angiography showed nonconforming focal choroidal excavation in the setting of choroidal inflammation and the presence of choroidal neovascularization at the border of the excavation, nicely visualized by optical coherence tomography angiography. Pattern alteration from nonconforming to conforming focal choroidal excavation and choroidal neovascularization involution were observed after treatment with oral steroids. Multimodal imaging, including optical coherence tomography angiography, allowed to detect and monitor pattern focal choroidal excavation transformation and choroidal neovascularization reduction after treatment with oral steroids.

  12. Recent progress of choroidal hemangioma

    Directory of Open Access Journals (Sweden)

    Li Miao

    2013-04-01

    Full Text Available Choroidal hemangioma(CHis a benign vascular tumor that occurred in the fundus posterior pole. Although it is a benign tumor, exudation from the lesion can lead to retinal detachment and other complications that make visual loss for patients. CH can occur as a circumscribed choroidal hemangioma(CCH, generally without systemic associations, or as a diffuse choroidal hemangioma(DCHthat is often associated variations of Sturge-weber syndrome(SWS. The management of CH has included laser photocoagulation, radiation therapy, transpupillary thermotherapy(TTT, photodynamic therapy(PDT. This article aims to introduce the current situation and the latest progress of the various therapies, to explore the most safe and effective method for the treatment of CH.

  13. A peptide derived from type 1 thrombospondin repeat-containing protein WISP-1 inhibits corneal and choroidal neovascularization.

    Science.gov (United States)

    Cano, Marisol del Valle; Karagiannis, Emmanouil D; Soliman, Mohamed; Bakir, Belal; Zhuang, Wenjuan; Popel, Aleksander S; Gehlbach, Peter L

    2009-08-01

    Ocular neovascularization is the primary cause of blindness in a wide range of prevalent ocular diseases including proliferative diabetic retinopathy, exudative age-related macular degeneration, and retinopathy of prematurity, among others. Antiangiogenic therapies are starting to give promising results in these diseases. In the present study the antiangiogenic potential of an 18-mer peptide derived from type 1 thrombospondin repeat-containing protein WISP-1 (wispostatin-1) was analyzed in vitro with human retinal endothelial cell proliferation and migration assays. The peptide was also tested in vivo in the corneal micropocket and the laser-induced choroidal neovascularization (CNV) mouse models. Human retinal endothelial cells were treated with the WISP-1 peptide and in vitro migration and proliferation assays were performed. Also evaluated was the antiangiogenic effect of this peptide in vivo using the corneal micropocket assay and the laser-induced CNV model. Wispostatin-1 derived peptide demonstrated antimigratory and antiproliferative activity in vitro. Wispostatin-1 completely abolished bFGF-induced neovascularization in the corneal micropocket assay. The peptide also demonstrated significant inhibition of laser-induced CNV. An inhibitory effect of Wispostatin-1 on ocular neovascularization was found in vitro and in vivo. The identification of novel and potent endogenous peptide inhibitors provides insight into the pathogenesis of corneal and choroidal neovascularization. The results demonstrate potential for therapeutic application in prevalent ocular disease.

  14. Laser Induced Fluorescence on Molecular Discharges

    Science.gov (United States)

    Mulders, Hjalmar; Rijke, Arij; Girault, Vincent; Stoffels, Winfred

    2008-10-01

    In the last half century, mercury has been used widely as the radiating species in many low pressure fluorescent lamps. Mercury primarily radiates at 254 nm and 185 nm. These photons excite a phosphor that fluoresces back to the ground state producing visible photons. This process reduces the efficiency because much of the energy of the UV photons has to be discarded. Using a species that emits light closer to or even in the visible range reduces these losses. Ideally the species (or a mixture of several species) should build up the whole visible spectrum, much like in HID lamps. InBr seems to be a good candidate for such a lamp, because it is an efficient radiator that emits most of its light around 370 nm; much closer to the visible part of the spectrum. In order to get insight in the energy transfer processes going on in these molecules we have conducted a laser induced fluorescence (LIF) experiment on InBr vapour and on a plasma. We have measured the decay times of different rovibrational levels of the InBr-molecule as well as the spectral distribution of the fluorescence from these levels. From the former we calculated the rotational temperature of the plasma and from the latter we calculated the Franck-Condon factors for the A-state as well as the vibrational temperature.

  15. Laser Induced Fluorescence of the Iodine Ion

    Science.gov (United States)

    Hargus, William

    2014-10-01

    Iodine (I2) has been considered as a potential electrostatic spacecraft thruster propellant for approximately 2 decades, but has only recently been demonstrated. Energy conversion efficiency appears to be on par with xenon without thruster modification. Intriguingly, performance appears to exceed xenon at high acceleration potentials. As part of a continuing program for the development of non-intrusive plasma diagnostics for advanced plasma spacecraft propulsion, we have identified the I II 5d5D4 o state as metastable, and therefore containing a reservoir of excited state ions suitable for laser probing. The 5d5D4 o - 6p5P3 transition at 695.878 nm is convenient for diode laser excitation with the 5s5S2 o - 6p5P3 transition at 516.12 nm as an ideal candidate for non-resonant fluorescence collection. We have constructed a Penning type iodine microwave discharge lamp optimized for I II production for table-top measurements. This work demonstrates I II laser-induced fluorescence in a representative iodine discharge and will validate our previous theoretical work based on the limited available historical I II spectral data.

  16. Femtosecond Laser Induced Underwater Superoleophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Yong Jiale

    2015-01-01

    Full Text Available Femtosecond laser microfabrication has been recently utilized in interface science to modify the liquid wettability of solid surfaces. Silicon surface with hierarchical micro/nanostructure is fabricated by a femtosecond laser. Similar to the fish’s scales, the laser-induced surface shows superhydrophilicity in air and superoleophobicity underwater. The oil contact angles can reach up to 159.4 ± 1° for the 1,2-dichloroethane droplets in water. Besides, the surface exhibits ultralow oil-adhesion. In the oil/water/solid three-phase system, water can be trapped in the hierarchical rough structure and forms a repulsive oil layer according to underwater Cassie’s theory. The contact area between the asprepared surface and oil droplet is significantly reduced, resulting in superoleophobicity and ultralow oil-adhesion in water. In addition, transparent underwater superoleophobic and anti-oil surfaces are achieved on silica glass surfaces by femtosecond laser ablation. This transparent property is attributed to the presence of the water environment because scattering and refraction are effectively weakened. The presented method is simple and can accurately control the processing location, which may have widely potential applications in, for instance, microfluidics, biotechnologies, and antifouling coatings.

  17. Medical Applications of Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    Pathak, A. K.; Rai, N. K.; Singh, Ankita; Rai, A. K.; Rai, Pradeep K.; Rai, Pramod K.

    2014-11-01

    Sedentary lifestyle of human beings has resulted in various diseases and in turn we require a potential tool that can be used to address various issues related to human health. Laser Induced Breakdown Spectroscopy (LIBS) is one such potential optical analytical tool that has become quite popular because of its distinctive features that include applicability to any type/phase of samples with almost no sample preparation. Several reports are available that discusses the capabilities of LIBS, suitable for various applications in different branches of science which cannot be addressed by traditional analytical methods but only few reports are available for the medical applications of LIBS. In the present work, LIBS has been implemented to understand the role of various elements in the formation of gallstones (formed under the empyema and mucocele state of gallbladder) samples along with patient history that were collected from Purvancal region of Uttar Pradesh, India. The occurrence statistics of gallstones under the present study reveal higher occurrence of gallstones in female patients. The gallstone occurrence was found more prevalent for those male patients who were having the habit of either tobacco chewing, smoking or drinking alcohols. This work further reports in-situ LIBS study of deciduous tooth and in-vivo LIBS study of human nail.

  18. Compact High Sensitive Laser-Induced Breakdown Spectroscopy Instrument Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser induced breakdown spectroscopy (LIBS) is a versatile tool for in situ substance characterization. Existing LIBS instruments are not compact enough for space...

  19. Physics and applications with laser-induced relativistic shock waves

    National Research Council Canada - National Science Library

    S Eliezer; J M Martinez-Val; Z Henis; N Nissim; S V Pinhasi; A Ravid; M Werdiger; E Raicher

    2016-01-01

    The laser-induced relativistic shock waves are described. The shock waves can be created directly by a high irradiance laser or indirectly by a laser acceleration of a foil that collides with a second static foil...

  20. [Self-inflicted laser-induced maculopathy in adolescence].

    Science.gov (United States)

    Hohberger, B; Bergua, A

    2017-03-01

    Reports of laser-induced ocular injuries have become more frequent in recent years, especially due to high-energy laser pointers. The article presents for the first time in the German literature a case of self-inflicted laser-induced maculopathy in an adolescent. In addition to the clinical findings, the results of funduscopy and spectral domain optical coherence tomography (SD-OCT) follow-up are presented.

  1. Choroidal Osteoma and Secondary Choroidal Neovascularization Treated with Ranibizumab

    Directory of Open Access Journals (Sweden)

    Almila Sarıgül Sezenöz

    2017-08-01

    Full Text Available A 47-year-old female patient presented with a complaint of decreased vision in the right eye. Her visual acuity was 0.16 in the right eye and 1.0 in the left eye. Fundus examination revealed a slightly elevated, yellowish-white lesion with regular borders at the macula of the right eye. Early and late hyperfluorescence related with choroidal neovascularization (CNV was detected in the right eye on fundus fluorescein angiography. B-scan ultrasonography revealed a hyperechoic choroidal lesion with acoustic shadowing. The lesion was diagnosed as choroidal osteoma. The patient received 3 injections of intravitreal ranibizumab. After 4 months, the visual acuity of the right eye was 0.9 and the CNV had regressed. Follow-up at about 7 months revealed reduced visual acuity in the right eye with an increase in subretinal fluid. An additional ranibizumab injection was administered. In this case report, we discuss the findings and treatment of a rare case of choroidal osteoma with secondary CNV.

  2. Morphological studies of laser-induced photoacoustic damage

    Science.gov (United States)

    Flotte, Thomas J.; Yashima, Yutaka; Watanabe, Shinichi; McAuliffe, Daniel J., Sr.; Jacques, Steven L.

    1990-06-01

    Argon-fluoride excimer laser ablation of stratum comeum causes deeper tissue damage than expected for thermal or photochemical mechanisms, suggesting thatphotoacoustic waves have arole in tissue damage. Laserirradiation (193 nm, 14 ns pulses, 1-2 Hz) attworadiantexposures, 60 and 160 mJ/cm2perpulse was usedto ablate the stratumcomeumofskin. Light and electron microscopy ofimmediate biopsies demonstrated damage to fibroblasts as deep as 88 and 220 jun, respectively, below the ablation site. Ablation throughwaterwas usedtoinertially confine the ablation zone. Partial ablationofs.c. through airproducedno damage, whereas partial ablation through water damaged skin to amean depth of 1 14.5 8.8( Full thickness ablation of s.c. through air and water produced damage zones measuring 192.2 16.2 and 293.0 71.6 rim, respectively (p mechanism ofdamage. The depths ofdamage for thelarge spot, line, and small spots were 43 1 164 urn, 269 96xni, andno damage. The spot size dependence ofthedepthofdamage is consistentwiththe geometric attenuation one would expect to be present from a pressure wave related phenomena. Sequential biopsies were taken over a 7 day period for light and transmission electron microscopy. At 24 hours, there was necrosis of the epidermis and papillary dermis subjacent to the ablation site, with neutrophils surrounding and demarcating the affected area. The necrotic zone sloughedby48 hours. Thereepithelializationwas completeby7 days. The sequenceofrepairis similartoknife wound healing which we have previously studied, and is analogous to other wound healing processes. We have used an experimental model of ArF excimer laser ablation of stratum corneum to investigate laser-induced photoacoustic damage. The evidence for the injury being due to pressure transients is indirectbutcompelling. Whether these pressuretransients are acoustic transients orshockwaves has notbeendetermined, although itis ourprejudicethatshockwaves are the predominant force under these

  3. Metal surface nitriding by laser induced plasma

    Science.gov (United States)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  4. MALIGNANT TRANSFORMATION OF A CHOROIDAL NEVUS IN AN EYE TREATED FOR CHOROIDAL MELANOMA.

    Science.gov (United States)

    Fabian, Ido D; Arora, Amit K; Cohen, Victoria M L

    2017-01-01

    To report a case of a choroidal melanoma and a discrete choroidal nevus that has transformed into a malignant melanoma 5 years after initial diagnosis. Retrospective case report. A diffuse macular choroidal melanoma and a discrete choroidal nevus located superonasal to the optic disk were diagnosed in the right eye of a 63-year-old woman in 2009. The patient was treated by ruthenium plaque radiotherapy for the choroidal melanoma, which consequently flattened and scarred. On a routine eye check in 2014, the nevus was found to have been transformed into a choroidal melanoma. It was treated with ruthenium plaque radiotherapy. Although extremely rare, patients with a uveal melanoma can develop an additional discrete uveal melanoma. This case highlights the importance of monitoring benign choroidal nevi in patients with a history of choroidal melanoma.

  5. Two-dimensional axisymmetric models of laser induced plasmas relevant to laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shabanov, S.V., E-mail: shabanov@math.ufl.edu [Department of Mathematics, University of Florida, Gainesville, FL 32611 (United States); BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, 12489 Berlin (Germany); Gornushkin, I.B. [BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, 12489 Berlin (Germany)

    2014-10-01

    A dynamical model of a laser induced plasma with axial symmetry is developed to systematically study the effects of the plasma equation of state, radiation transfer, various transport phenomena (viscosity, thermal conductivity, diffusion), and the ablation surface on the observable quantities such as spectra emitted by LIBS plasmas containing multiple species. Theoretical and numerical foundations of the model are described in detail. It is shown that the plasma spectra simulated with the equation of state based on the energy balance that includes the kinetic (thermal) energy, ionization energy, and energy of electronic excitations in atoms and ions differ significantly from the spectra obtained for plasmas modeled in the ideal gas approximation (where only the kinetic energy is included into the energy balance). Various transport phenomena, such as viscosity, diffusion, and thermal conductivity, are shown to have a little effect on the spectra. Radiation losses are proved to have noticeable effects. The effects of various interactions (adhesion, heat exchange, mass inflows) of the evolving plasma with the ablation surface are also illustrated by numerical simulations for typical LIBS plasmas. The model provides a numerical tool to assess various settings for LIBS plasma experiments as well as to interpret experimental data. - Highlights: • A gas dynamic model of laser induced plasma with axial symmetry is developed. • The effects of the plasma equation of state, radiation transfer, transport phenomena, and the ablation surface on the plasma evolution and the plasma spectra are systematically studied. • Numerous numerical simulations visualize the physical portrait of the plasma at different stages of its evolution. • The model provides a numerical tool to assess various settings for LIBS plasma experiments and to interpret experimental data.

  6. Nonconforming Deep Focal Choroidal Excavation in a Patient With Choroidal Osteoma: A Diagnostic Dilemma.

    Science.gov (United States)

    Chawla, Rohan; Azad, Shorya Vardhan; Takkar, Brijesh; Sharma, Anu; Kashyap, Bibhuti

    2017-11-01

    Evolution of an osteoma may result in neurosensory detachment, deossification, and choroidal neovascularization (CNV). The authors report a rare case of choroidal osteoma with CNV associated with a deep non-conforming focal choroidal excavation. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:944-947.]. Copyright 2017, SLACK Incorporated.

  7. BILATERAL CHOROIDAL EXCAVATION IN JUVENILE LOCALIZED SCLERODERMA.

    Science.gov (United States)

    Franklin, Mackenzie L; Day, Shelley

    2018-01-01

    To describe a case of bilateral choroidal excavation in a patient with juvenile localized scleroderma. Case report. An asymptomatic 12-year-old boy with localized scleroderma presented for examination and was found to have bilateral areas of choroidal excavation temporal to the fovea. Previous reports of ocular complications of localized scleroderma have primarily described adnexal and anterior segment changes. This is the second report of choroidal changes in a patient with localized scleroderma, and the first in a pediatric patient.

  8. Study on choroidal neovascularization with anti-VEGF treatment in the mouse retina using optical coherence tomography angiography (Conference Presentation)

    Science.gov (United States)

    Park, Jang Ryul; Choi, WooJhon; Kim, Jaeryung; Hong, Hye Kyong; Kim, Yongjoo; Hwang, Yoonha; Park, Sang Jun; Woo, Se Joon; Kim, Pilhan; Park, Kyu Hyung; Koh, Gou Young; Oh, Wang-Yuhl

    2017-02-01

    To understand the pathogenesis of ophthalmic disease, utilizing small animal models such as mouse is necessary because of their ease of maintenance and availability. For identifying pathophysiology and drug development of retinal diseases in mouse model, optical coherence tomography angiography (OCTA) is promising imaging modality visualizing not only microstructure but also microvasculature. In this study, we serially imaged 3D structure and angiography of laser-induced choroidal neovascularization (CNV) in the mouse retina with/without anti-VEGF treatment. Also, the volume changes of CNV and avascular region in choroid layer are measured for identifying effects of anti-VEGF. A lab-built high-speed OCTA prototype using the wavelength-swept laser centered at 1040 nm with 230 kHz A-scan rate acquired 3-D volumetric data consisted of 1024 x 1024 x 3 A-scans. The OCTA scanned 1.7 mm x 1.7 mm area around ONH. For obtaining angiography, amplitude decorrelation from 3 consecutive B-scans at each position was generated. Seven days after the laser photocoagulation at mouse retina for generation of the laser-induced CNV, intravitreal administration of Fc and VEGF-Trap was given in the therapeutic arm. The OCTA were performed at 6, 14, 21 and 35 days after laser photocoagulation. Vasculatures of inner retina, outer retina and choroid layers were separately visualized after RPE flattening and layer segmentation. To investigate therapeutic effects of anti-VEGF treatment, the relative area and volume of CNV in outer retina layer is measured. Also, total volume of avascular zone surrounding the laser injury site in choroid layer is also analyzed.

  9. [Transpupillary thermotherapy of choroidal melanomas].

    Science.gov (United States)

    Forte, R; Cennamo, G

    2008-03-01

    To evaluate the effectiveness of transpupillary thermotherapy (TTT) as a single treatment of choroidal melanomas. We studied a series of 50 cases of choroidal melanoma treated with TTT and evaluated them with standardized A-scan and B-scan echography before and after treatment (1 week, 1, 3, and 6 months after treatment, then every 6 months). There were 22 males and 28 females with a mean age of 57 years (range, 22-78). The mean thickness of the lesion was 2.7 +/- 0.6 mm (range, 1.63-3.72). The mean follow-up was 38 months (range, 21-41). In almost all the eyes treated with TTT, substantial regression of tumoral microcirculation was observed after 1 week associated with a 70%-80% reduction in tumor thickness after 6 months (stabilized during follow-up). In one case of juxtapapillary melanoma with a thickness of 3.72 mm, another TTT application was necessary for local relapse. Visual acuity (VA) decreased to 20/30 in two cases (4%) and to 20/200 in four cases (8%) after the development of a cystoid macular edema. These latter patients were treated with two intravitreal injections (range, 1-3) of triamcinolone acetonide, and after a follow-up of 25 months (range, 21-29) VA improved to 20/20 in the first two cases, while two of the four other cases improved to 20/40 and two to 20/30. Transpupillary thermotherapy has visual results similar to those obtained with irradiation for the treatment of choroidal melanomas. Nevertheless, considering the high rate of recurrence at 5 and 10 years after transpupillary thermotherapy alone, most authors think that transpupillary thermotherapy is useful when associated irradiation for the treatment of choroidal melanomas, but its precise indications need to be defined.

  10. Unusual Orange-Colored Choroidal Metastases

    Directory of Open Access Journals (Sweden)

    Hatem Krema

    2013-01-01

    Full Text Available Purpose: To report the clinical and paraclinical features of two patients with orangecolored choroidal metastases in whom the primary cancers have not previously been associated with such lesions. Case Report: Orange-colored choroidal lesions were detected on the fundus examination of one patient with metastatic small cell neuroendocrine tumor of the larynx and oropharynx, and in another subject with metastatic alveolar soft part sarcoma of the leg. Although ultrasonographic characteristics of the choroidal masses were comparable to those of choroidal hemangiomas, fluorescein angiography revealed delayed initial fluorescence along with minimal fluorescence in subsequent phases of the angiogram which were in clear distinction from the earlier appearing and progressively intense fluorescence observed with circumscribed choroidal hemangiomas. Conclusion: Small cell neuroendocrine tumors and alveolar soft part sarcomas should be considered among the differential diagnoses for orange-colored choroidal metastases. Identifying these choroidal lesions could facilitate localizing the occult primary tumor. Fluorescein angiography may differentiate a unifocal orange choroidal metastasis from a circumscribed choroidal hemangioma.

  11. Clinical applications of choroidal imaging technologies

    Directory of Open Access Journals (Sweden)

    Jay Chhablani

    2015-01-01

    Full Text Available Choroid supplies the major blood supply to the eye, especially the outer retinal structures. Its understanding has significantly improved with the advent of advanced imaging modalities such as enhanced depth imaging technique and the newer swept source optical coherence tomography. Recent literature reports the findings of choroidal changes, quantitative as well as qualitative, in various chorioretinal disorders. This review article describes applications of choroidal imaging in the management of common diseases such as age-related macular degeneration, high myopia, central serous chorioretinopathy, chorioretinal inflammatory diseases, and tumors. This article briefly discusses future directions in choroidal imaging including angiography.

  12. CHOROIDAL SARCOID GRANULOMA SIMULATING PROSTATE CARCINOMA METASTASIS.

    Science.gov (United States)

    Turkoglu, Elif B; Lally, Sara E; Shields, Carol L

    2017-01-01

    To report a case of choroidal sarcoid granuloma simulating choroidal metastasis in a patient with prostate carcinoma. Case report. A 66-year-old man was found to have an asymptomatic choroidal mass in his left eye. He had known history of pulmonary sarcoidosis without systemic involvement and prostate carcinoma without metastasis. On examination, visual acuity was 20/20 in each eye. Anterior segment was normal, without inflammatory sign in either eye. The right fundus was healthy. The left fundus revealed a yellow choroidal mass of 2 mm diameter, temporal to the foveola and without subretinal fluid, retinitis, or vitritis. Optical coherence tomography demonstrated a homogenous hyporeflective choroidal mass with intact retinal pigment epithelium and compression of choroidal vascular structures. Given the medical history and rarity of prostate metastasis to the uvea, choroidal sarcoid granuloma was considered and oral prednisone with a slow taper was given. After 2 months of therapy, tumor resolution with reduction in size was confirmed on optical coherence tomography. Choroidal sarcoid granuloma is a rare condition that can simulate choroidal metastasis. Treatment with prednisone can assist in establishing the diagnosis.

  13. Laser-induced grating in ZnO

    DEFF Research Database (Denmark)

    Ravn, Jesper N.

    1992-01-01

    A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self-diffracti......A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self...

  14. Neural control of choroidal blood flow.

    Science.gov (United States)

    Reiner, Anton; Fitzgerald, Malinda E C; Del Mar, Nobel; Li, Chunyan

    2017-12-08

    The choroid is richly innervated by parasympathetic, sympathetic and trigeminal sensory nerve fibers that regulate choroidal blood flow in birds and mammals, and presumably other vertebrate classes as well. The parasympathetic innervation has been shown to vasodilate and increase choroidal blood flow, the sympathetic input has been shown to vasoconstrict and decrease choroidal blood flow, and the sensory input has been shown to both convey pain and thermal information centrally and act locally to vasodilate and increase choroidal blood flow. As the choroid lies behind the retina and cannot respond readily to retinal metabolic signals, its innervation is important for adjustments in flow required by either retinal activity, by fluctuations in the systemic blood pressure driving choroidal perfusion, and possibly by retinal temperature. The former two appear to be mediated by the sympathetic and parasympathetic nervous systems, via central circuits responsive to retinal activity and systemic blood pressure, but adjustments for ocular perfusion pressure also appear to be influenced by local autoregulatory myogenic mechanisms. Adaptive choroidal responses to temperature may be mediated by trigeminal sensory fibers. Impairments in the neural control of choroidal blood flow occur with aging, and various ocular or systemic diseases such as glaucoma, age-related macular degeneration (AMD), hypertension, and diabetes, and may contribute to retinal pathology and dysfunction in these conditions, or in the case of AMD be a precondition. The present manuscript reviews findings in birds and mammals that contribute to the above-summarized understanding of the roles of the autonomic and sensory innervation of the choroid in controlling choroidal blood flow, and in the importance of such regulation for maintaining retinal health. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Transscleral sustained vasohibin-1 delivery by a novel device suppressed experimentally-induced choroidal neovascularization.

    Directory of Open Access Journals (Sweden)

    Hideyuki Onami

    Full Text Available We established a sustained vasohibin-1 (a 42-kDa protein, delivery device by a novel method using photopolymerization of a mixture of polyethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and collagen microparticles. We evaluated its effects in a model of rat laser-induced choroidal neovascularization (CNV using a transscleral approach. We used variable concentrations of vasohibin-1 in the devices, and used an enzyme-linked immunosorbent assay and Western blotting to measure the released vasohibin-1 (0.31 nM/day when using the 10 μM vasohibin-1 delivery device [10VDD]. The released vasohibin-1 showed suppression activity comparable to native effects when evaluated using endothelial tube formation. We also used pelletized vasohibin-1 and fluorescein isothiocyanate-labeled 40 kDa dextran as controls. Strong fluorescein staining was observed on the sclera when the device was used for drug delivery, whereas pellet use produced strong staining in the conjunctiva and surrounding tissue, but not on the sclera. Vasohibin-1 was found in the sclera, choroid, retinal pigment epithelium (RPE, and neural retina after device implantation. Stronger immunoreactivity at the RPE and ganglion cell layers was observed than in other retinal regions. Significantly lower fluorescein angiography (FA scores and smaller CNV areas in the flat mounts of RPE-choroid-sclera were observed for the 10VDD, VDD (1 μM vasohibin-1 delivery device, and vasohibin-1 intravitreal direct injection (0.24 μM groups when compared to the pellet, non-vasohibin-1 delivery device, and intravitreal vehicle injection groups. Choroidal neovascularization can be treated with transscleral sustained protein delivery using our novel device. We offer a safer sustained protein release for treatment of retinal disease using the transscleral approach.

  16. Laser-Induced Breakdown Spectroscopy and Chlorophyll a Flourescence Transients

    DEFF Research Database (Denmark)

    Frydenvang, Jens

    of a sufficient quality; something that remains a problem for many in-situ methods. In my PhD, I present my work with two such in-situ methods, Laser-Induced Breakdown Spectroscopy (LIBS) and OJIP transients, the rising part of chlorophyll a fluorescence transients from dark-adapted leaves....

  17. Gas permeation and temperature effects in laser-induced delamination

    NARCIS (Netherlands)

    Fedorov, Alexander; Vellinga, Willem-Pier; De Hosson, Jeff

    Laser-induced delamination (LID) is a technique aimed at measuring the work of adhesion of thin polymer coatings on metal substrates. A laser Pulse is used to create a blister that initiates delamination of the film under pressure. The stress fields in the blister wall and the work of adhesion of

  18. Laser-induced fluorescence of oral mucosa cancer

    Science.gov (United States)

    Jaliashvili, Z. V.; Medoidze, T. D.; Melikishvili, Z. G.; Gogilashvili, K. T.

    2017-10-01

    The laser-induced fluorescence (LIF) spectra have been measured for cancer-infused and control mice mucosa tissues. It was established that there is quite a difference between their LIF spectral shapes. These spectral shapes are used to express the diagnostic of different states of tissues: from normal to cancer.

  19. Measurements of egg shell plasma parameters using laser-induced ...

    Indian Academy of Sciences (India)

    Measurements of 1064 nm laser-induced egg shell plasma parameters are presented in this paper. Of special interests were its elemental identification and the determination of spectroscopic temperature and electron density. The electron temperature of 5956 K was inferred using an improved iterative Boltzmann plot ...

  20. Application of laser-induced breakdown spectroscopy in carbon ...

    Indian Academy of Sciences (India)

    2014-07-18

    Jul 18, 2014 ... We propose the use of laser-induced breakdown spectroscopy (LIBS) analytical technique to detect carbon dioxide leaks to aid in the successful application of CCS. LIBS has a real-time ... This work details the laboratory scale experiments to measure carbon contents in soil, aqueous, and air samples.

  1. Laser induced damage threshold on metallic surfaces during laser cleaning

    CSIR Research Space (South Africa)

    Labuschagne, K

    2005-07-01

    Full Text Available laser paint removal. Laser induced damage on 316L stainless steel was studied, with the target subjected to single and multiple pulse irradiations using a Q-switched Nd:YAG, with fluences between 0.15 and 11.8 J/cm2. Several different damage morphologies...

  2. Laser-induced breakdown spectroscopy and inductively coupled ...

    African Journals Online (AJOL)

    Laser-induced breakdown spectroscopy (LIBS) is an emerging analytical technique, which can be used to perform elemental analysis of any material, irrespective of its physical state. In this study, the LIBS technique has been applied for quantification of total Cr in soil samples collected from polluted areas of Brits, North ...

  3. Erratum to: Measurement of copper vapour laser-induced ...

    Indian Academy of Sciences (India)

    Erratum to: Measurement of copper vapour laser-induced deformation of dielectric-coated mirror surface by. Michelson interferometer. A WAHID. ∗. , S KUNDU, J S B SINGH, A K SINGH, A KHATTAR,. S K MAURYA, J S DHUMAL and K DASGUPTA. Laser & Plasma Technology Division, Beam Technology Development ...

  4. Measurement of gas flow velocities by laser-induced gratings

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B.; Stampanoni-Panariello, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kozlov, A.D.N. [General Physics Institute, Moscow (Russian Federation)

    1999-08-01

    Time resolved light scattering from laser-induced electrostrictive gratings was used for the determination of flow velocities in air at room temperature. By measuring the velocity profile across the width of a slit nozzle we demonstrated the high spatial resolution (about 200 mm) of this novel technique. (author) 3 figs., 1 ref.

  5. Transport across the choroid plexus epithelium.

    Science.gov (United States)

    Praetorius, Jeppe; Damkier, Helle Hasager

    2017-06-01

    The choroid plexus epithelium is a secretory epithelium par excellence. However, this is perhaps not the most prominent reason for the massive interest in this modest-sized tissue residing inside the brain ventricles. Most likely, the dominant reason for extensive studies of the choroid plexus is the identification of this epithelium as the source of the majority of intraventricular cerebrospinal fluid. This finding has direct relevance for studies of diseases and conditions with deranged central fluid volume or ionic balance. While the concept is supported by the vast majority of the literature, the implication of the choroid plexus in secretion of the cerebrospinal fluid was recently challenged once again. Three newer and promising areas of current choroid plexus-related investigations are as follows: 1) the choroid plexus epithelium as the source of mediators necessary for central nervous system development, 2) the choroid plexus as a route for microorganisms and immune cells into the central nervous system, and 3) the choroid plexus as a potential route for drug delivery into the central nervous system, bypassing the blood-brain barrier. Thus, the purpose of this review is to highlight current active areas of research in the choroid plexus physiology and a few matters of continuous controversy. Copyright © 2017 the American Physiological Society.

  6. Transpupillary Thermotherapy for Classic Subfoveal Choroidal ...

    African Journals Online (AJOL)

    Dr. Oderinlo

    fundus fluorescein angiography were done, a diagnosis of a classic subfoveal choroidal neovascularization secondary to exudative age-related macular degeneration OS with bilateral cataracts and primary open angle glaucoma OU was made. Complete resolution of the choroidal neovascular membrane was achieved ...

  7. Decalcified choroidal osteoma found in the retina

    Directory of Open Access Journals (Sweden)

    Yoshikawa T

    2012-11-01

    Full Text Available Tadanobu Yoshikawa, Kanji TakahashiDepartment of Ophthalmology, Kansai Medical University, Hirakata Hospital, Osaka, JapanAbstract: Choroidal osteoma is a benign tumor of the choroid. Herein, we report a rare case of decalcified choroidal osteoma found in the retina. A 27-year-old woman presented with visual loss. Her best-corrected visual acuity was 20/50 OS. Ophthalmoscopy of the left eye revealed a yellow-white calcified region accompanied by a decalcified region of four disc diameters in size. After 6 years, spectral-domain optical coherence tomography showed a tumor projected strongly upwards from the choroid and partially through the retina with serous retinal detachment, with both a lamellar appearance and mound-like area. The calcified region became more contractive than was observed on the first visit. Conversely, the decalcified region was wider than was observed on the first visit. Her best-corrected visual acuity was 20/400 OS. Choroidal osteoma was worsened by progression of decalcification. The decalcified choroidal osteoma resulted in poor visual acuity, and projected strongly upward from the choroid and into the retina.Keywords: osteoma, decalcification, choroidal osteoma

  8. VEGF receptor blockade markedly reduces retinal microglia/macrophage infiltration into laser-induced CNV.

    Directory of Open Access Journals (Sweden)

    Hu Huang

    Full Text Available Although blocking VEGF has a positive effect in wet age-related macular degeneration (AMD, the effect of blocking its receptors remains unclear. This was an investigation of the effect of VEGF receptor (VEGFR 1 and/or 2 blockade on retinal microglia/macrophage infiltration in laser-induced choroidal neovascularization (CNV, a model of wet AMD. CNV lesions were isolated by laser capture microdissection at 3, 7, and 14 days after laser and analyzed by RT-PCR and immunofluorescence staining for mRNA and protein expression, respectively. Neutralizing antibodies for VEGFR1 or R2 and the microglia inhibitor minocycline were injected intraperitoneally (IP. Anti-CD11b, CD45 and Iba1 antibodies were used to confirm the cell identity of retinal microglia/macrophage, in the RPE/choroidal flat mounts or retinal cross sections. CD11b(+, CD45(+ or Iba1(+ cells were counted. mRNA of VEGFR1 and its three ligands, PlGF, VEGF-A (VEGF and VEGF-B, were expressed at all stages, but VEGFR2 were detected only in the late stage. PlGF and VEGF proteins were expressed at 3 and 7 days after laser. Anti-VEGFR1 (MF1 delivered IP 3 days after laser inhibited infiltration of leukocyte populations, largely retinal microglia/macrophage to CNV, while anti-VEGFR2 (DC101 had no effect. At 14 days after laser, both MF1 and DC101 antibodies markedly inhibited retinal microglia/macrophage infiltration into CNV. Therefore, VEGFR1 and R2 play differential roles in the pathogenesis of CNV: VEGFR1 plays a dominant role at 3 days after laser; but both receptors play pivotal roles at 14 days after laser. In vivo imaging demonstrated accumulation of GFP-expressing microglia into CNV in both CX3CR1(gfp/gfp and CX3CR1(gfp/+ mice. Minocycline treatment caused a significant increase in lectin(+ cells in the sub-retinal space anterior to CNV and a decrease in dextran-perfused neovessels compared to controls. Targeting the chemoattractant molecules that regulate trafficking of retinal microglia

  9. THE SPECTRUM OF AMALRIC TRIANGULAR CHOROIDAL INFARCTION.

    Science.gov (United States)

    Nemiroff, Julia; Phasukkijwatana, Nopasak; Vaclavik, Veronika; Nagiel, Aaron; Holz, Eric R; Sarraf, David

    2017-01-01

    To describe the multimodal imaging findings, including optical coherence tomography angiography analysis, and spectrum of etiologies associated with Amalric triangular choroidal infarction. This study is a multicenter, retrospective, observational case series review of the clinical and multimodal imaging findings for six patients with Amalric triangular choroidal infarction. Six patients (10 eyes) with Amalric triangular choroidal infarction were enrolled. Patients' ages ranged from 7 years to 90 years (mean 54 years, median 60 years). Wedge-shaped or triangular areas of choroidal ischemia were evident with fluorescein angiography in all patients and with indocyanine green angiography in one patient. Optical coherence tomography angiography demonstrated choriocapillaris flow reduction that colocalized with outer retinal structural abnormalities with en face optical coherence tomography and corresponded with the triangular zones of choroidal infarction identified with fluorescein angiography in one patient. Etiologies included giant cell arteritis in three cases: traumatic carotid dissection, traumatic retrobulbar hemorrhage, and malignant hypertension secondary to lupus-associated nephropathy. The Amalric triangular syndrome of choroidal infarction can occur as a result of a spectrum of etiologies, especially giant cell arteritis. Infarction is evident on traditional angiography in all cases. Optical coherence tomography angiography may provide a simple noninvasive tool to evaluate choroidal ischemia.

  10. Choroidal neovascularization associated with coloboma of the choroid: A series of three cases

    Directory of Open Access Journals (Sweden)

    Bhende Muna

    2011-01-01

    Full Text Available Choroidal neovascularization (CNV is a rare complication associated with coloboma of the choroid. We describe three cases of coloboma choroid where there was loss of vision due to CNV development at the edge of the coloboma. One was managed by photodynamic therapy alone and two were managed by a combination of reduced fluence PDT and intravitreal bevacizumab. Significantly we noted that one treatment session was sufficient to achieve regression of the CNV and improvement in visual acuity.

  11. Radiation therapy for metastatic choroidal tumors

    Energy Technology Data Exchange (ETDEWEB)

    Ochiai, Yuko; Sunakawa, Mitsuko (National Kyoto Hospital (Japan)); Hiraoka, Masahiro

    1992-03-01

    We treated 3 eyes in 2 cases of metastatic choroidal malignancy by applying x-ray angled 5deg from a linear accelerator. One case was a 35-year-old female with breast cancer metastasized in both choroids. The second was a 59-year-old male with choroidal metastasis in one eye from malignant lymphoma of the cerebellum. Immediate regression of the tumor followed in all the eyes with resolution of secondary retinal detachment. The treatment was free of complications including cataract or corneal erosion. (author).

  12. Heritability of Choroidal Thickness in the Amish.

    Science.gov (United States)

    Sardell, Rebecca J; Nittala, Muneeswar G; Adams, Larry D; Laux, Reneé A; Cooke Bailey, Jessica N; Fuzzell, Denise; Fuzzell, Sarada; Reinhart-Mercer, Lori; Caywood, Laura J; Horst, Violet; Mackay, Tine; Dana, Debbie; Sadda, SriniVas R; Scott, William K; Stambolian, Dwight; Haines, Jonathan L; Pericak-Vance, Margaret A

    2016-12-01

    To evaluate the heritability of choroidal thickness and its relationship to age-related macular degeneration (AMD). Cohort study. Six hundred eighty-nine individuals from Amish families with early or intermediate AMD. Ocular coherence tomography was used to quantify choroidal thickness, and fundus photography was used to classify eyes into categories using a modified Clinical Age-Related Maculopathy Staging (CARMS) system. Repeatability and heritability of choroidal thickness and its phenotypic and genetic correlations with the AMD phenotype (CARMS category) were estimated using a generalized linear mixed model (GLMM) approach that accounted for relatedness, repeated measures (left and right eyes), and the effects of age, gender, and refraction. Heritability of choroidal thickness and its phenotypic and genetic correlation with the AMD phenotype (CARMS category). Phenotypic correlation between choroidal thickness and CARMS category was moderate (Spearman's rank correlation, rs = -0.24; n = 1313 eyes) and significant (GLMM posterior mean, -4.27; 95% credible interval [CI], -7.88 to -0.79; P = 0.02) after controlling for relatedness, age, gender, and refraction. Eyes with advanced AMD had thinner choroids than eyes without AMD (posterior mean, -73.8; 95% CI, -94.7 to -54.6; P < 0.001; n = 1178 eyes). Choroidal thickness was highly repeatable within individuals (repeatability, 0.78; 95% CI, 0.68 to 0.89) and moderately heritable (heritability, 0.40; 95% CI, 0.14 to 0.51), but did not show significant genetic correlation with CARMS category, although the effect size was moderate (genetic correlation, -0.18; 95% CI, -0.49 to 0.16). Choroidal thickness also varied with age, gender, and refraction. The CARMS category showed moderate heritability (heritability, 0.49; 95% CI, 0.26 to 0.72). We quantify the heritability of choroidal thickness for the first time, highlighting a heritable, quantitative trait that is measurable in all individuals regardless of AMD

  13. Flexible temperature and flow sensor from laser-induced graphene

    KAUST Repository

    Marengo, Marco

    2017-12-25

    Herein we present a flexible temperature sensor and a flow speed sensor based on laser-induced graphene. The main benefits arise from peculiar electrical, thermal and mechanical performances of the material thus obtained, along with a cheap and simple fabrication process. The temperature sensor is a negative temperature coefficient thermistor with non-linear response typical of semi-metals. The thermistor shows a 4% decrease of the resistance in a temperature range of 20–60 °C. The flow sensor exploits the piezoresistive properties of laser-induced graphene and can be used both in gaseous and liquid media thanks to a protective polydimethylsiloxane coating. Main characteristics are ultra-fast response and versatility in design offered by the laser technology.

  14. Laser Induced Selective Activation For Subsequent Autocatalytic Electroless Plating

    DEFF Research Database (Denmark)

    Zhang, Yang

    The subject of this PhD thesis is “Laser induced selective activation for subsequent autocatalytic electroless plating.” The objective of the project is to investigate the process chains for micro structuring of polymer surfaces for selective micro metallization. Laser induced selective activation...... that chemical bonds exist. However, it is still not excluded that chemical bonding is part of the mechanism. The second hypothesis is that the laser track has a stronger attraction work to the activation solution. This is proved by a calculation using van Oss et al., theory based on contact angle measurement....... The third hypothesis is that the activation and rinsing process can be described by diffusion. This hypothesis is proved using Fick’s diffusion laws combined with the short-time-plating experiment. The influence of laser parameters on the surface structure is investigated for Nd:YAG, UV, and fiber lasers...

  15. Compositional Analysis of Drugs by Laser-Induced Breakdown Spectroscopy

    Science.gov (United States)

    Beldjilali, S. A.; Axente, E.; Belasri, A.; Baba-Hamed, T.; Hermann, J.

    2017-07-01

    The feasibility of the compositional analysis of drugs by calibration-free laser-induced breakdown spectroscopy (LIBS) was investigated using multivitamin tablets as a sample material. The plasma was produced by a frequencyquadrupled Nd:YAG laser delivering UV pulses with a duration of 5 ns and an energy of 12 mJ, operated at a repetition rate of 10 Hz. The relative fractions of the elements composing the multivitamin drug were determined by comparing the emission spectrum of the laser-produced plume with the spectral radiance computed for a plasma in a local thermodynamic equilibrium. Fair agreement of the measured fractions with those given by the manufacturer was observed for all elements mentioned in the leafl et of the drug. Additional elements such as Ca, Na, Sr, Al, Li, K, and Si were detected and quantifi ed. The present investigations demonstrate that laser-induced breakdown spectroscopy is a viable technique for the quality control of drugs.

  16. Applications of laser-induced gratings to spectroscopy and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rohlfing, E.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    This program has traditionally emphasized two principal areas of research. The first is the spectroscopic characterization of large-amplitude motion on the ground-state potential surface of small, transient molecules. The second is the reactivity of carbonaceous clusters and its relevance to soot and fullerene formation in combustion. Motivated initially by the desire to find improved methods of obtaining stimulated emission pumping (SEP) spectra of transients, most of our recent work has centered on the use of laser-induced gratings or resonant four-wave mixing in free-jet expansions. These techniques show great promise for several chemical applications, including molecular spectroscopy and photodissociation dynamics. The author describes recent applications of two-color laser-induced grating spectroscopy (LIGS) to obtain background-free SEP spectra of transients and double resonance spectra of nonfluorescing species, and the use of photofragment transient gratings to probe photodissociation dynamics.

  17. Laser-Induced Chemical Vapour Deposition of Silicon Carbonitride

    OpenAIRE

    Besling, W.; van der Put, P.; Schoonman, J.

    1995-01-01

    Laser-induced Chemical Vapour Deposition of silicon carbonitride coatings and powders has been investigated using hexamethyldisilazane (HMDS) and ammonia as reactants. An industrial CW CO2-laser in parallel configuration has been used to heat up the reactant gases. HMDS dissociates in the laser beam and reactive radicals are formed which increase rapidly in molecular weight by an addition mechanism. Dense polymer-like silicon carbonitride thin films and nanosized powders are formed depending ...

  18. Laser-induced transient grating setup with continuously tunable period

    Energy Technology Data Exchange (ETDEWEB)

    Vega-Flick, A. [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Applied Physics Department, CINVESTAV-Unidad Mérida, Carretera Antigua a Progreso Km 6, Cordemex, Mérida, Yucatán 97310 Mexico (Mexico); Eliason, J. K.; Maznev, A. A.; Nelson, K. A., E-mail: kanelson@mit.edu [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Khanolkar, A.; Abi Ghanem, M.; Boechler, N. [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Alvarado-Gil, J. J. [Applied Physics Department, CINVESTAV-Unidad Mérida, Carretera Antigua a Progreso Km 6, Cordemex, Mérida, Yucatán 97310 Mexico (Mexico)

    2015-12-15

    We present a modification of the laser-induced transient grating setup enabling continuous tuning of the transient grating period. The fine control of the period is accomplished by varying the angle of the diffraction grating used to split excitation and probe beams. The setup has been tested by measuring dispersion of bulk and surface acoustic waves in both transmission and reflection geometries. The presented modification is fully compatible with optical heterodyne detection and can be easily implemented in any transient grating setup.

  19. Choroidal osteoma with choroidal neovascular membrane: Successful treatment with intravitreal bevacizumab

    Directory of Open Access Journals (Sweden)

    Neeraj Pandey

    2010-09-01

    Full Text Available Neeraj Pandey, Ayachit GuruprasadMM Joshi Eye Institute, Hubli, Karnataka, IndiaAbstract: An otherwise healthy 27-year-old woman presented with complaints of sudden painless blurred vision in the right eye for one week. On examination, visual acuity was 20/30 in the right eye and 20/20 in left eye. Fundus examination OS was normal, but OD demonstrated an elevated, opaque, yellowish parapapillary choroidal lesion with grayish membrane associated with minimal subretinal fluid, suggestive of a choroidal neovascular membrane in the center. B-scan ultrasonography revealed findings consistent with a choroidal osteoma. Fundus fluorescein angiography of the right eye revealed a relatively well defined area of hyperfluorescence that increased in size and intensity in the later phases, suggestive of active extrafoveal choroidal neovascular membrane. Optical coherence tomography confirmed the extrafoveal choroidal neovascular membrane with subfoveal fluid. She was treated with intravitreal bevacizumab OD. At the two-week visit, vision OD improved to 20/20. Fluorescein angiography and optical coherence tomography revealed a resolved choroidal neovascular membrane. Intravitreal bevacizumab may be an effective alternative in the management of choroidal neovascular membrane secondary to choroidal osteoma.Keywords: osteoma, choroidal neovascular membrane, optical coherence tomography, bevacizumab

  20. All-SPEEK flexible supercapacitor exploiting laser-induced graphenization

    Science.gov (United States)

    Lamberti, A.; Serrapede, M.; Ferraro, G.; Fontana, M.; Perrucci, F.; Bianco, S.; Chiolerio, A.; Bocchini, S.

    2017-09-01

    Flexible supercapacitors have emerged as one of the more promising and efficient space-saving energy storage system for portable and wearable electronics. Laser-induced graphenization has been recently proposed as a powerful and scalable method to directly convert a polymeric substrate into a 3D network of few layer graphene as high-performance supercapacitor electrode. Unfortunately this outstanding process has been reported to be feasible only for few thermoplastic polymers, strongly limiting its future developments. Here we show that laser induced graphenization of sulfonated poly(ether ether ketone) (SPEEK) can be obtained and the mechanism of this novel process is proposed. The resulting material can act at the same time as binder-free electrode and current collector. Moreover SPEEK is also used both as separator and polymeric electrolyte allowing the assembling of an all-SPEEK flexible supercapacitor. Chemico-physical characterization provides deep understanding of the laser-induced graphenization process, reported on this polymer for the first time, while the device performance studied by cyclic voltammetry, charging-discharging, and impedance spectroscopy prove the enormous potential of the proposed approach.

  1. Differential diagnosis of choroidal melanomas and nervi using scanning laser ophthalmoscopical indocyanine green angiography

    DEFF Research Database (Denmark)

    Andersen, Mads V. Nis; Scherfig, Erik; Prause, J.U.

    1995-01-01

    Ophthalmology, choroidal melanoma, choroidal nevus, fluorescein angiography, indocyanine green (ICG), scanning laser ophthalmoscope (SLO), angiography......Ophthalmology, choroidal melanoma, choroidal nevus, fluorescein angiography, indocyanine green (ICG), scanning laser ophthalmoscope (SLO), angiography...

  2. Determinations of trace boron in superalloys and steels using laser-induced breakdown spectroscopy assisted with laser-induced fluorescence.

    Science.gov (United States)

    Li, Changmao; Hao, Zhongqi; Zou, Zhimin; Zhou, Ran; Li, Jiaming; Guo, Lianbo; Li, Xiangyou; Lu, Yongfeng; Zeng, Xiaoyan

    2016-04-18

    Boron (B) is widely applied in microalloying of metals. As a typical light element, however, determination of boron in alloys with complex matrix spectra is still a challenge for laser-induced breakdown spectroscopy (LIBS) due to its weak line intensities in the UV-visible-NIR range and strong spectral interference from the matrix spectra. In this study, a wavelength-tunable laser was used to enhance the intensities of boron lines selectively. The intensities of B I 208.96 nm from boron plasmas were enhanced approximately 3 and 5.8 times while the wavelength-tunable laser was tuned to 249.68 and 249.77 nm, respectively. Utilizing the selective enhancement effect, accurate determinations of trace boron in nickel-based superalloys and steels were achieved by laser-induced breakdown spectroscopy assisted by laser-induced fluorescence (LIBS-LIF), with limits of detection (LoDs) of 0.9 and 0.5 ppm, respectively. The results demonstrated that LIBS-LIF can hopefully be used in boron determinations and has great potential for improving the ability of LIBS to determine light elements in alloys with a complex matrix.

  3. Inhibition of the recombinant human endostatin adenavirus on experimental choroidal neovascularization in rats

    Directory of Open Access Journals (Sweden)

    Li-Juan Chen

    2017-06-01

    Full Text Available AIM: To investigate the inhibition of the recombinant human endostatin adenavirus(Ad-Eson the experimental choroidal neovascularization(CNVmodels by intravitreous injection. METHODS: Experimental CNV models were induced by semiconductor laser in 30 male Brown Norway(BNrats and randomly divided into 3 groups with 10 rats in each group. At 21d after photocoagulation, the single administration group were given intravitreous injection with Ad-Es 0.01mL; the repeated administration group were given intravitreous injection with Ad-Es 0.01mL and a repeated injection 7d later; the saline control group were given intravitreous injection with saline 0.01mL. At 7d after final administration, the leakage of fundus fluorescein angiography(FFAwas observed. Various CNV areas were measured by using laser confocal microscopy of choroidal flatmount method. Pathology and ultrastructure were observed with light microscopy, the expressions of CD105 were measured by immunohistochemistry. RESULTS: The leakage of CNV of the administration group abviously decreased as compared with those in the saline group, the leakage of repeated administration group decreased compared with that of single administration group(PPCONCLUSION: Ad-Es can effectively inhibit semiconductor laser induced CNV in BN rats, and the inhibition effect of repeated administration group is better than that of single administration group. It may be a useful new method in the treatment of CNV.

  4. 805-nm diode-laser-induced release of liposome-encapsulated dye for quantification of chorioretinal thermal damage: in-vivo study on a rabbit eye model

    Science.gov (United States)

    Mordon, Serge R.; Desmettre, Thomas; Devoisselle, Jean-Marie; Begu, Sylvie; Mitchell, Valerie A.

    1998-01-01

    This study aimed to evaluate the feasibility of retinal thermal damage assessment in a rabbit eye model by using laser-induced release of liposome-encapsulated dye. After anethesia, thermosensitive liposomes (DSPC) loaded with 5,6- Carboxyfluorescein were injected intravenously to pigmented rabbits. Retinal photocoagulation were performed with a 810 nm diode laser (P equals 100 to 400 mW, (Phi) equals 500 micrometer, ls). Fluorescence measurements in the area of the laser exposures were then realized with a digitized angiograph. Histology was performed on retinal tissue and adjacent ares. Fluorescent spots were observed for fluences ranging from 50 plus or minus 10 J/cm2 to 210 plus or minus 10 J/cm2. The fluorescence intensity increased linearly with the fluence and reached a plateau at 150 plus or minus 10 J/cm2. The fluorescence intensity was correlated to the maximum temperature at the center of the laser spot with a linear increase from 42 plus or minus 3 degrees Celsius to 65 plus or minus 3 degrees Celsius. The chorioretinal thermal damage quantified by histology was correlated to temperature. These results are in agreement with our two previous studies with DSPC liposomes for temperature measurements in a tissue model and then in a vascular model. In conclusion, this study demonstrates the possibility of a laser-induced release of liposome-encapsulated dye for a quantification of diode laser induced thermal damage in ophthalmology. Such a method could be useful for a real-time monitoring of laser photocoagulation for condition such as choroidal neovessels when a precise thermal damage is required near the foveolar area.

  5. Macrophage activation associated with chronic murine cytomegalovirus infection results in more severe experimental choroidal neovascularization.

    Directory of Open Access Journals (Sweden)

    Scott W Cousins

    Full Text Available The neovascular (wet form of age-related macular degeneration (AMD leads to vision loss due to choroidal neovascularization (CNV. Since macrophages are important in CNV development, and cytomegalovirus (CMV-specific IgG serum titers in patients with wet AMD are elevated, we hypothesized that chronic CMV infection contributes to wet AMD, possibly by pro-angiogenic macrophage activation. This hypothesis was tested using an established mouse model of experimental CNV. At 6 days, 6 weeks, or 12 weeks after infection with murine CMV (MCMV, laser-induced CNV was performed, and CNV severity was determined 4 weeks later by analysis of choroidal flatmounts. Although all MCMV-infected mice exhibited more severe CNV when compared with control mice, the most severe CNV developed in mice with chronic infection, a time when MCMV-specific gene sequences could not be detected within choroidal tissues. Splenic macrophages collected from mice with chronic MCMV infection, however, expressed significantly greater levels of TNF-α, COX-2, MMP-9, and, most significantly, VEGF transcripts by quantitative RT-PCR assay when compared to splenic macrophages from control mice. Direct MCMV infection of monolayers of IC-21 mouse macrophages confirmed significant stimulation of VEGF mRNA and VEGF protein as determined by quantitative RT-PCR assay, ELISA, and immunostaining. Stimulation of VEGF production in vivo and in vitro was sensitive to the antiviral ganciclovir. These studies suggest that chronic CMV infection may serve as a heretofore unrecognized risk factor in the pathogenesis of wet AMD. One mechanism by which chronic CMV infection might promote increased CNV severity is via stimulation of macrophages to make pro-angiogenic factors (VEGF, an outcome that requires active virus replication.

  6. Retinal Inhibition of CCR3 Induces Retinal Cell Death in a Murine Model of Choroidal Neovascularization.

    Directory of Open Access Journals (Sweden)

    Haibo Wang

    Full Text Available Inhibition of chemokine C-C motif receptor 3 (CCR3 signaling has been considered as treatment for neovascular age-related macular degeneration (AMD. However, CCR3 is expressed in neural retina from aged human donor eyes. Therefore, broad CCR3 inhibition may be harmful to the retina. We assessed the effects of CCR3 inhibition on retina and choroidal endothelial cells (CECs that develop into choroidal neovascularization (CNV. In adult murine eyes, CCR3 colocalized with glutamine-synthetase labeled Műller cells. In a murine laser-induced CNV model, CCR3 immunolocalized not only to lectin-stained cells in CNV lesions but also to the retina. Compared to non-lasered controls, CCR3 mRNA was significantly increased in laser-treated retina. An intravitreal injection of a CCR3 inhibitor (CCR3i significantly reduced CNV compared to DMSO or PBS controls. Both CCR3i and a neutralizing antibody to CCR3 increased TUNEL+ retinal cells overlying CNV, compared to controls. There was no difference in cleaved caspase-3 in laser-induced CNV lesions or in overlying retina between CCR3i- or control-treated eyes. Following CCR3i, apoptotic inducible factor (AIF was significantly increased and anti-apoptotic factor BCL2 decreased in the retina; there were no differences in retinal vascular endothelial growth factor (VEGF. In cultured human Műller cells exposed to eotaxin (CCL11 and VEGF, CCR3i significantly increased TUNEL+ cells and AIF but decreased BCL2 and brain derived neurotrophic factor, without affecting caspase-3 activity or VEGF. CCR3i significantly decreased AIF in RPE/choroids and immunostaining of phosphorylated VEGF receptor 2 (p-VEGFR2 in CNV with a trend toward reduced VEGF. In cultured CECs treated with CCL11 and/or VEGF, CCR3i decreased p-VEGFR2 and increased BCL2 without increasing TUNEL+ cells and AIF. These findings suggest that inhibition of retinal CCR3 causes retinal cell death and that targeted inhibition of CCR3 in CECs may be a safer if CCR3

  7. Idiopathic multifocal choroiditis/punctate inner choroidopathy with acute photoreceptor loss or dysfunction out of proportion to clinically visible lesions.

    Science.gov (United States)

    Munk, Marion R; Jung, Jesse J; Biggee, Kristin; Tucker, William R; Sen, H Nida; Schmidt-Erfurth, Ursula; Fawzi, Amani A; Jampol, Lee M

    2015-02-01

    To report acute/subacute vision loss and paracentral scotomata in patients with idiopathic multifocal choroiditis/punctate inner choroidopathy due to large zones of acute photoreceptor attenuation surrounding the chorioretinal lesions. Multimodal imaging case series. Six women and 2 men were included (mean age, 31.5 ± 5.8 years). Vision ranged from 20/20-1 to hand motion (mean, 20/364). Spectral domain optical coherence tomography demonstrated extensive attenuation of the external limiting membrane, ellipsoid and interdigitation zones, adjacent to the visible multifocal choroiditis/punctate inner choroidopathy lesions. The corresponding areas were hyperautofluorescent on fundus autofluorescence and were associated with corresponding visual field defects. Full-field electroretinogram (available in three cases) showed markedly decreased cone/rod response, and multifocal electroretinogram revealed reduced amplitudes and increased implicit times in two cases. Three patients received no treatment, the remaining were treated with oral corticosteroids (n = 4), oral acyclovir/valacyclovir (n = 2), intravitreal/posterior subtenon triamcinolone acetate (n = 3), and anti-vascular endothelial growth factor (n = 2). Visual recovery occurred in only three cases of whom two were treated. Varying morphological recovery was found in six cases, associated with decrease in hyperautofluorescence on fundus autofluorescence. Multifocal choroiditis/punctate inner choroidopathy can present with transient or permanent central photoreceptor attenuation/loss. This presentation is likely a variant of multifocal choroiditis/punctate inner choroidopathy with chorioretinal atrophy. Associated changes are best evaluated using multimodal imaging.

  8. The expanded spectrum of focal choroidal excavation.

    Science.gov (United States)

    Margolis, Ron; Mukkamala, Sri Krishna; Jampol, Lee M; Spaide, Richard F; Ober, Michael D; Sorenson, John A; Gentile, Ronald C; Miller, Joel A; Sherman, Jerome; Freund, K Bailey

    2011-10-01

    To describe the clinical and imaging findings in patients with focal choroidal excavation. Retrospective observational case series. The medical records of 12 patients (13 eyes) with focal choroidal excavation were reviewed. Clinical histories and imaging findings (including color photography, fundus autofluorescence imaging, fluorescein angiography, indocyanine green angiography, spectral-domain optical coherence tomography, and enhanced depth imaging spectral-domain optical coherence tomography) were analyzed. The mean age of the patients was 45 years (range, 22-62 years). Four patients were Asian. Mean visual acuity was 20/31 (range, 20/20 to 20/100). Mean refractive error was -3.54 diopters (D) (range, 6.00 to -8.00 D). One patient had bilateral involvement. All patients manifested varying degrees of foveal pigmentary changes that were usually hypoautofluorescent on fundus autofluorescence images. Fluorescein angiographic findings varied with degree of retinal pigment epithelial alterations. Indocyanine green angiography revealed relative hypofluorescence. In 7 eyes, spectral-domain optical coherence tomography revealed outer retinal layers conforming to retinal pigment epithelial alterations within the excavation. In the other 6 eyes, spectral-domain optical coherence tomography revealed a separation between the outer retina and the retinal pigment epithelium within the excavation. In 7 eyes studied with enhanced depth imaging spectral-domain optical coherence tomography, there was no evidence of scleral ectasia. Mean choroidal thickness of the uninvolved choroid was thicker than normal at 319 μm (range, 244-439 μm). All lesions remained stable except for in 1 eye, which had findings of central serous chorioretinopathy and secondary type 2 (subretinal) neovascularization. Focal choroidal excavation is a newly described idiopathic entity in eyes having 1 or more focal areas of choroidal excavation. In some patients, there may be an association with central

  9. Deoxycytidine transport and metabolism in choroid plexus

    Energy Technology Data Exchange (ETDEWEB)

    Spector, R.; Huntoon, S.

    1983-05-01

    In vitro, the transport into and release of (/sup 3/H)deoxycytidine from the isolated choroid plexus, the anatomical locus of the blood-cerebrospinal fluid barrier, were studied separately. By use of the ability of nitrobenzylthioinosine (NBTI) to inhibit deoxycytidine efflux from choroid plexus, the transport of 1 microM (/sup 3/H)deoxycytidine into choroid plexus at 37 degrees C was measured. Deoxycytidine was transported into choroid plexus against a concentration gradient by a saturable process that depended on intracellular energy production, but not intracellular binding or metabolism. The Michaelis-Menten constant (KT) for the active transport of deoxycytidine into choroid plexus was 15 microM. The active transport system for deoxycytidine was inhibited by naturally occurring nucleosides and deoxynucleosides, but not by 1 mM probenecid and 2-deoxyribose or 100 microM cytosine and cytosine arabinoside. With less than 1 microM (/sup 3/H)deoxycytidine in the medium, the choroid plexus accumulated (/sup 3/H)deoxycytidine against a concentration gradient. However, approximately 50% of the (/sup 3/H)deoxycytidine was phosphorylated to (/sup 3/H)deoxycytidine nucleotides at a low extracellular (/sup 3/H)deoxycytidine concentration (6 nM) in 15-min incubations. This accumulation process depended, in part, on saturable intracellular phosphorylation. These studies provide further evidence that the choroid plexus contains an active nucleoside transport system of low specificity for deoxynucleosides and ribonucleosides, and a separate, saturable efflux system for deoxynucleosides which is very sensitive to inhibition by NBTI.

  10. Anomalous laser-induced group velocity dispersion in fused silica.

    Science.gov (United States)

    Rasskazov, Gennady; Ryabtsev, Anton; Pestov, Dmitry; Nie, Bai; Lozovoy, Vadim V; Dantus, Marcos

    2013-07-29

    We present 20fs(2) accuracy laser-induced group velocity dispersion (LI-GVD) measurements, resulting from propagation of a femtosecond laser pulse in 1mm of fused silica, as a function of peak intensity. For a 5.5 × 10(11) W/cm(2) peak intensity, LI-GVD values are found to vary from -3 to + 15 times the material GVD. Normal induced dispersion can be explained by the Kerr effect, but anomalous LI-GVD, found when the input pulses have negative pre-chirp, cannot. These findings have significant implications regarding self-compression and the design of femtosecond lasers.

  11. Laser induced fluorescence of biochemical for UV LIDAR application.

    Science.gov (United States)

    Gupta, L; Sharma, R C; Razdan, A K; Maini, A K

    2014-05-01

    Laser induced fluorescence spectroscopy in the ultraviolet regime has been used for the detection of biochemical through a fiber coupled CCD detector from a distance of 2 m. The effect of concentration and laser excitation energy on the fluorescence spectra of nicotinamide adenine dinucleotide (NADH) has been investigated. The signature fluorescence peak of NADH was centred about 460 nm. At lower concentration Raman peak centred at 405 nm was also observed. The origin of this peak has been discussed. Detection limit with the proposed set up is found to be 1 ppm.

  12. First ionization potential measurements using laser-induced breakdown spectroscopy

    OpenAIRE

    Sherbini, Ahsraf M. EL; Faham, Mohamed M. EL; Parigger, Christian G.

    2016-01-01

    The first ionization potential of neutral atoms is determined from thresholds of laser-induced optical breakdown. Bulk material ablation plasma of aluminum, silver, lead, indium and copper is created in laboratory air with focused, 5-ns pulsed Nd:YAG, 1064 nm IR radiation. At fixed spot size of 2 $\\pm$ 0.1 mm, the laser fluence is varied from 16 to 3 J/cm$^2$. The first ionization potentials of the lines Al I 396.2, Ag I 520.9, Pb I 405.8 and 406.2, In I 410.2 and Cu I 515.3 nm are measured t...

  13. Multiple structure of a laser-induced underwater shock wave

    CERN Document Server

    Tagawa, Yoshiyuki; Hayasaka, Keisuke; Kameda, Masaharu

    2015-01-01

    The structure of a laser-induced underwater shock wave is examined. Plasma formation, shock-wave expansion, and temporal evolution of shock pressure are observed simultaneously using a combined measurement system that obtains high-resolution nanosecond-order image sequences. In contrast to a well-known spherical-shock model, these detailed measurements reveal a non-spherically-symmteric distribution of pressure peak for a wide range of experimental parameters. The structure is determined to be a collection of multiple spherical shocks originated from elongated plasmas.

  14. Urinary incontinence monitoring system using laser-induced graphene sensors

    KAUST Repository

    Nag, Anindya

    2017-12-25

    This paper presents the design and development of a sensor patch to be used in a sensing system to deal with the urinary incontinence problem primarily faced by women and elderly people. The sensor patches were developed from laser-induced graphene from low-cost commercial polyimide (PI) polymers. The graphene was manually transferred to a commercial tape, which was used as sensor patch for experimentation. Salt solutions with different concentrations were tested to determine the most sensitive frequency region of the sensor. The results are encouraging to further develop this sensor in a platform for a fully functional urinary incontinence detection system.

  15. Choroid Melanoma Metastasis to Spine: A Rare Case Report

    OpenAIRE

    Hiren Mandaliya; Nandini Singh; Sanila George; Mathew George

    2016-01-01

    Metastatic choroid melanoma is a highly malignant disease with a limited life expectancy. The liver is the most common site for metastasis of uveal melanoma followed by lung, bone, skin, and subcutaneous tissue. Metastasis from choroidal melanoma usually occurs within the first five years of treatment for primary tumours. Metastatic choroid melanoma to the spine/vertebrae is extremely rare. We report the first case of spinal metastasis from choroid melanoma in a 61-year-old man who had been t...

  16. Subretinal lipid exudation associated with untreated choroidal melanoma

    Directory of Open Access Journals (Sweden)

    C K Minija

    2011-01-01

    Full Text Available Subretinal lipid exudation in an untreated choroidal melanoma is very rare. It is seen following plaque radiotherapy in choroidal melanoma. There is only one case report of untreated choroidal melanoma with massive lipid exudation in a patient with metastatic hypernephroma. We report here a rare case of untreated choroidal melanoma with lipid exudation. Subretinal exudation that is rarely seen following plaque brachytherapy was noted at the borders of this untreated tumor. Lipid exudation partially resolved following brachytherapy.

  17. Bilateral choroidal tumors consistent with metastatic malignant paraganglioma.

    Science.gov (United States)

    Aaberg, Thomas M; Benjamin, Erin P; Biscotti, Charles V; Singh, Arun D

    2013-01-01

    To report a patient with bilateral choroidal metastasis from a malignant paraganglioma. Clinicopathologic case report and literature review. A 68-year-old woman presented with bilateral amelanotic focal choroidal lesions. A thorough systemic work-up for a primary cancer revealed a paraganglioma (extraadrenal pheochromocytoma) and a pheochromocytoma of the left adrenal gland. Fine-needle aspiration biopsy of the choroidal lesion was consistent with metastatic paraganglioma. Metastatic paraganglioma, although rare, has the ability to metastasize to the choroid.

  18. [Disorders of choroidal circulation in diabetic maculopathy].

    Science.gov (United States)

    Takamine, Y

    1998-08-01

    Diabetic maculopathy is classified into 3 types, namely, macular edema, ischemic maculopathy, and pigment epitheliopathy. Blood-retinal barrier disturbance and the influence of the posterior vitreous membrane have been reported as the cause of diabetic maculopathy. However, its association with the choroidal circulation feeding the outer layer of the retina which involves the outer blood-retinal barrier has not been clarified yet. In this work, we studied the presence of the choroidal circulatory disturbance by performing indocyanine green angiography (IA) on patients with diabetic maculopathy. Choroidal circulatory disturbance was also differentiated from fluorescent block with a scanning laser ophthalmoscope (SLO). The proportion of hypofluorescence observed in IA was 4 eyes in 2 patients among 37 eyes in 24 patients (11%) in the macular edema group, 3 eyes in 2 patients among 14 eyes in 10 patients (21%) in the ischemic maculopathy group, and 26 eyes in 17 patients among 33 eyes in 22 patients (79%) in the pigment epitheliopathy group. Of the cases showing hypofluorescence in IA in the pigment epitheliopathy group, 4 eyes in 4 patients had hypofluorescence due to both choroidal circulatory disturbance and fluorescent block. This suggests that the choroidal circulation disturbance is partly involved in diabetic maculopathy mainly in the pigment epitheliopathy group.

  19. Single intravitreal ranibizumab for myopic choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Shatriah I

    2011-08-01

    Full Text Available Saidin Nor-Masniwati, Ismail Shatriah, Embong ZunainaDepartment of Ophthalmology, Universiti Sains Malaysia, Kelantan, MalaysiaAbstract: We report a case of myopic choroidal neovascularization that showed improvement after a single injection of ranibizumab. A 45-year-old Chinese man with high myopia presented with sudden onset painless central scotoma of his right eye of 2 weeks’ duration. There was no history of trauma. His right eye vision on presentation was 6/30 which showed no improvement with pinhole. The right fundus showed myopic maculopathy at the posterior pole with subretinal hemorrhage at the inferotemporal fovea. The optic disc was tilted with inferotemporal peripapillary atrophy. There was a myopic maculopathy appearance in the macula of the left eye. Fundus fluorescein angiography revealed choroidal neovascularization at the fovea of the right eye. A diagnosis of right eye choroidal neovascularization secondary to myopic maculopathy was made. A single intravitreal injection of ranibizumab 0.05 mL was given. Ten weeks following intravitreal injection, vision had improved to 6/7.5, and repeated fundus fluorescein angiography showed absence of choroidal neovascularization. Follow-up at 6 months showed visual acuity had normalized to 6/6 with glasses, which was maintained up to 12 months following treatment. The right fundus showed no further subretinal hemorrhage with no new lesions.Keywords: myopia, choroidal neovascularization, antivascular endothelial growth factor

  20. Direct probing of chromatography columns by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    McGuffin, V.L.

    1992-12-07

    This report summarizes the progress and accomplishments of this research project from September 1, 1989 to February 28, 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe insupercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  1. Adsorption and laser-induced desorption of dimethylcadmium from silicon

    Science.gov (United States)

    Simonov, Alexander P.; Varakin, Vladimir N.

    1990-10-01

    The dynamics of Cd (cH ) 2 chemisorption and spontaneous decomposit ion on n-type 51(100) with native surface oxide the pathwa and efficiencies of the adsorbate desorption due to the absorption of the XeC1 laser radiation by silicon have been examined using laser-induced desorption miss spectrorrtry (LIDMS ) . The k inetics of these sur face processes has been found to depend on the preceding laser irradiation of the surface. The extremely fast chemisorption and efficient decomposition of the parent rrlecules have been observed on the irradiated silicon surface. The competition between intact dissociative and recombination desorption pathways was responsible for the observed laser fluence dependences of the desorption of Cd(CI-6) and i ts fragments. 1 . INTROOIJCTIct4 1 . 1 . Laser chemical vapour depos ition (LCVD). Laser-induced deposition of thin filme on solid surfaces by using volatile organometallic precursors has been the subject of numerous investigations in the 8Os2. Due to the spatial/temporal localization of laser radiation and the resonant nature of laser-rr1ecule interaction this deposition technique has such attractive features as submicrometer resolution of deposits high film growth rate and high quality lowtemperature processing. The deposition process can be controlled by varying the laser parameters (wavelength fluence beam spot on the substrate surface scanning speed ). A var iety of mater ials can be depos I ted using LCVD. Of special interest for microelectronics is the deposition of

  2. UV-laser induced birefringence in olygoetheracrylate photopolymers

    Science.gov (United States)

    Ozga, K.

    2018-01-01

    Laser induced birefringence was studied during coherent treatment by two coherent UV laser beams at wavelength 355 nm. Principal role of the border separating photo-solidified and the surrounding non-solidified liquid-like fragments is demonstrated. The magnitudes of laser induced birefringence for probing 1150 nm wavelength were varied within 10-4…10-2. It is demonstrated that one can operate by values of the birefringence versus polymer solidification time. The UV-induced birefringence achieves a saturation after about 45 days. The reversible birefringence after switching off of the UV-solidification beams was equal to about 18% with respect to initially photo-stimulated. The discovered effect may be used for design and fabrication of electro-optical modulators operated by UV laser light. A principal physical mechanism is determined by an interaction between two coherent UV- nanosecond laser pulses at wavelengths of 355 nm (third harmonic of Nd:YAG laser). The discovered effects allow to propose a new type of UV-operated photopolymer materials for optical recoding of information.

  3. Laser-induced breakdown spectroscopy of tantalum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq [Centre for Advanced Studies in Physics, GC University, Lahore (Pakistan)

    2013-07-15

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO{sub 2}: N{sub 2}: He), O{sub 2}, N{sub 2}, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

  4. Laser induced fluorescence imaging system for localization of nasopharyngeal carcinoma

    Science.gov (United States)

    Liu, Lina; Xie, Shusen

    2007-11-01

    A laser induced fluorescence imaging system for localization of Nasopharyngeal Carcinoma is developed. In this fluorescence imaging system, the fluorescence intensity with information of detected objection is gained by an image intensifier, which makes color information of the fluorescence image eliminated and the result is a monochrome image of the fluorescence with thermally induced noise. The monochrome fluorescence image is sent to a CCD and captured by an image board, which is controlled by a computer. Image processing is carried out to improve the image quality and therefore improve the system's ability to differentiate carcinomas from normal tissue. Gaussian smoothing is implemented in order to reduce the noise. Image binarizing process is realized to obtain an optimal threshold of the image. Image pixels with grey value below this threshold are assigned as diseased and those above are normal. A pseudo color processing is then accomplished to get better visual perception and understanding of the image, greatly increasing the detail resolution of the grey image. The processed image is then displayed on the screen of the computer in real time. The real time laser induced fluorescence imaging system with the image processing methods developed is efficient for localization of the nasopharyngeal carcinoma.

  5. Laser-induced nucleation of carbon dioxide bubbles

    Science.gov (United States)

    Ward, Martin R.; Jamieson, William J.; Leckey, Claire A.; Alexander, Andrew J.

    2015-04-01

    A detailed experimental study of laser-induced nucleation (LIN) of carbon dioxide (CO2) gas bubbles is presented. Water and aqueous sucrose solutions supersaturated with CO2 were exposed to single nanosecond pulses (5 ns, 532 nm, 2.4-14.5 MW cm-2) and femtosecond pulses (110 fs, 800 nm, 0.028-11 GW cm-2) of laser light. No bubbles were observed with the femtosecond pulses, even at high peak power densities (11 GW cm-2). For the nanosecond pulses, the number of bubbles produced per pulse showed a quadratic dependence on laser power, with a distinct power threshold below which no bubbles were observed. The number of bubbles observed increases linearly with sucrose concentration. It was found that filtering of solutions reduces the number of bubbles significantly. Although the femtosecond pulses have higher peak power densities than the nanosecond pulses, they have lower energy densities per pulse. A simple model for LIN of CO2 is presented, based on heating of nanoparticles to produce vapor bubbles that must expand to reach a critical bubble radius to continue growth. The results suggest that non-photochemical laser-induced nucleation of crystals could also be caused by heating of nanoparticles.

  6. Laser Induced Damage in Optical Materials: 6th ASTM Symposium.

    Science.gov (United States)

    Glass, A J; Guenther, A H

    1975-03-01

    The Sixth ASTM-ONR-NBS Symposium on Laser Induced Damage in Optical Materials was held at the National Bureau of Standards in Boulder, Colorado on 22-23 May 1974. Over 150 attendees at the Symposium heard thirty-one papers on topics relating to laser induced damage in crystalline and nonlinear optical materials, at dielectric surfaces, and in thin film coatings as well as discussions of damage problems in the ir region due both to cw and pulsed irradiation. In addition, several reports on the theoretical analysis of laser-materials interaction relative to the damage progress were given, along with tabulations of fundamental materials properties of importance in evaluation of optical material response to high-power laser radiation. Attention was given to high-power laser system design considerations that relate to improved system performance and reliability when various damage mechanisms are operable in such systems. A workshop on the machining of optics was held, and nine papers on various facets of the topic were presented dealing with machining procedures, surface characterization of machined elements, coating of machined components, and the polishing and damage resistance of polished, coated, and bare metal reflectors.

  7. Functional and genetic analysis of choroid plexus development in zebrafish

    Science.gov (United States)

    Henson, Hannah E.; Parupalli, Chaithanyarani; Ju, Bensheng; Taylor, Michael R.

    2014-01-01

    The choroid plexus, an epithelial-based structure localized in the brain ventricle, is the major component of the blood-cerebrospinal fluid barrier. The choroid plexus produces the cerebrospinal fluid and regulates the components of the cerebrospinal fluid. Abnormal choroid plexus function is associated with neurodegenerative diseases, tumor formation in the choroid plexus epithelium, and hydrocephaly. In this study, we used zebrafish (Danio rerio) as a model system to understand the genetic components of choroid plexus development. We generated an enhancer trap line, Et(cp:EGFP)sj2, that expresses enhanced green fluorescent protein (EGFP) in the choroid plexus epithelium. Using immunohistochemistry and fluorescent tracers, we demonstrated that the zebrafish choroid plexus possesses brain barrier properties such as tight junctions and transporter activity. Thus, we have established zebrafish as a functionally relevant model to study choroid plexus development. Using an unbiased approach, we performed a forward genetic dissection of the choroid plexus to identify genes essential for its formation and function. Using Et(cp:EGFP)sj2, we isolated 10 recessive mutant lines with choroid plexus abnormalities, which were grouped into five classes based on GFP intensity, epithelial localization, and overall choroid plexus morphology. We also mapped the mutation for two mutant lines to chromosomes 4 and 21, respectively. The mutants generated in this study can be used to elucidate specific genes and signaling pathways essential for choroid plexus development, function, and/or maintenance and will provide important insights into how these genetic mutations contribute to disease. PMID:25426018

  8. Choroid plexus carcinoma in adults: an extremely rare case ...

    African Journals Online (AJOL)

    Choroid plexus tumors are rare intraventricular papillary neoplasms derived from choroid plexus epithelium, which account for approximately 2% to 4% of intracranial tumors in children and 0.5% in adults. Almost all choroid plexus carcinomas are seen in children and are extremely rare in adults. Headache, diplopia, and ...

  9. Choroidal vasculature characteristics based choroid segmentation for enhanced depth imaging optical coherence tomography images

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qiang; Niu, Sijie [School of Computer Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yuan, Songtao; Fan, Wen, E-mail: fanwen1029@163.com; Liu, Qinghuai [Department of Ophthalmology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029 (China)

    2016-04-15

    Purpose: In clinical research, it is important to measure choroidal thickness when eyes are affected by various diseases. The main purpose is to automatically segment choroid for enhanced depth imaging optical coherence tomography (EDI-OCT) images with five B-scans averaging. Methods: The authors present an automated choroid segmentation method based on choroidal vasculature characteristics for EDI-OCT images with five B-scans averaging. By considering the large vascular of the Haller’s layer neighbor with the choroid-sclera junction (CSJ), the authors measured the intensity ascending distance and a maximum intensity image in the axial direction from a smoothed and normalized EDI-OCT image. Then, based on generated choroidal vessel image, the authors constructed the CSJ cost and constrain the CSJ search neighborhood. Finally, graph search with smooth constraints was utilized to obtain the CSJ boundary. Results: Experimental results with 49 images from 10 eyes in 8 normal persons and 270 images from 57 eyes in 44 patients with several stages of diabetic retinopathy and age-related macular degeneration demonstrate that the proposed method can accurately segment the choroid of EDI-OCT images with five B-scans averaging. The mean choroid thickness difference and overlap ratio between the authors’ proposed method and manual segmentation drawn by experts were −11.43 μm and 86.29%, respectively. Conclusions: Good performance was achieved for normal and pathologic eyes, which proves that the authors’ method is effective for the automated choroid segmentation of the EDI-OCT images with five B-scans averaging.

  10. Intravitreal bevacizumab (avastin for circumscribed choroidal hemangioma

    Directory of Open Access Journals (Sweden)

    Subrata Mandal

    2011-01-01

    Full Text Available Circumscribed choroidal hemangiomas are rare ophthalmic entities that cause diminution in vision due to accumulation of subretinal and/or intraretinal fluid in the macular area. Various treatment options ranging from conventional laser to photodynamic therapy have been employed to destroy the tumor and reduce the exudation; however, either the inability to penetrate through the exudative fluid or the collateral retinal damage induced by these treatment modalities make them unsuitable for lesions within the macula. We evaluated the role of intravitreal bevacizumab, a pan-vascular endothelial growth factor (VEGF inhibitor, in reducing the sub- and intraretinal fluid in three patients with circumscribed choroidal hemangiomas. All the patients had complete resolution of the serous retinal detachment that was maintained till at least 12 months after the first injection. Intravitreal bevacizumab may be used in combination with thermal laser or photodynamic therapy in treating circumscribed choroidal hemangiomas with subretinal fluid.

  11. Randomised clinical trials of choroidal melanoma treatment.

    Directory of Open Access Journals (Sweden)

    Straatsma Bradley

    2003-01-01

    Full Text Available Purpose: To illustrate an approach to evidence-based medical practice by reporting the Collaborative Ocular Melanoma Study (COMS randomised clinical trials and cohort studies of choroidal melanoma. Methods: COMS randomised clinical trials of Iodine-125 (I-125 brachytherapy, adjunctive cohort study of visual acuity in eyes treated with brachytherapy and adjunctive natural history study. COMS randomised clinical trial of pre-enucleation radiation. Results: The COMS I-125 brachytherapy trial (N = 1,317 patients of medium-sized choroidal melanoma showed 5-year all-cause mortality of 18% [95% Confidence Interval (CI, 16-20%] and no statistically significant difference in mortality following 1-125 brachytherapy or enucleation. Adjunctive cohort natural history study (N-42 patients of patients eligible for the I-125 brachytherapy trial who deferred treatment or had no melanoma treatment had a 5-year all-cause mortality of 30% (95% CI, 18-47%. The COMS pre-enucleation radiation trial (N = 1,003 patients of large-sized choroidal melanoma showed 5-year all-cause mortality of 40% (95% CI, 37-44%. Conclusions: Evidence derived from randomised clinical trials and cohort studies shows the need for longterm (ž 5 years follow-up to determine the efficacy of treatment for choroidal melanoma by any modality. The rather similar 5-year mortality for treated and untreated medium melanoma patients suggests that metastatic dissemination may occur at an early stage of choroidal melanoma. To increase longterm survival, ocular treatment of choroidal melanoma must strive for diagnosis and treatment of melanoma at an early stage when metastasis is less likely and be combined with measures to detect and treat micrometastasis

  12. Chemical and structural changes of quartz surfaces due to structuring by laser-induced backside wet etching.

    Science.gov (United States)

    Kopitkovas, G; Deckert, V; Lippert, T; Raimondi, F; Schneider, C W; Wokaun, A

    2008-06-14

    Various physical and chemical processes which are involved in laser-induced backside wet etching are investigated. The surface of quartz etched by the laser-induced backside wet etching using a XeCl excimer laser at various fluences is analyzed by Raman microscopy, X-ray photoelectron spectroscopy and fiber-tip attenuated total-reflection Fourier-transform infrared spectroscopy. The investigations reveal the formation of a high amount of amorphous carbon deposits at low laser fluences, which strongly adhere to the quartz surface. Combining X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy reveals that the quartz is also chemically and structurally modified due to a loss of oxygen and by a change of the quartz polymorph at intermediate and high laser fluences. These modification and their differences for different fluences are explained by the etching mechanisms itself, i.e. different magnitudes of temperature and pressure jumps. The results show clearly which conditions for etching must be applied to machine high-quality structures, e.g. micro-optical elements in quartz.

  13. Evaluation of laser-induced thin-layer removal by using shadowgraphy and laser-induced breakdown spectroscopy

    Science.gov (United States)

    Rabasović, M. S.; Šević, D.; Lukač, N.; Jezeršek, M.; Možina, J.; Gregorčič, P.

    2016-03-01

    Shadow photography and laser-induced breakdown spectroscopy (LIBS) are studied as methods for monitoring the selective removal of thin (i.e., under 100 μm) layers by laser ablation. We used a laser pulse of 5 ns and 16 mJ at 1064 nm to ablate an 18-μm-thin copper layer from the fiberglass substrate. On the basis of shadowgraphs of the laser-induced shock waves, we measured the optodynamic energy-conversion efficiency, defined as the ratio between the mechanical energy of the shock wave and the excitation-pulse energy. Our results show that this efficiency is significantly higher for the laser pulse-copper interaction than for the interaction between the excitation pulse and the substrate. LIBS was simultaneously employed in our experimental setup. The optical emission from the plasma plume was collected by using a spectrograph and recorded with a streak camera. We show that advancing of laser ablation through the copper layer and reaching of the substrate can be estimated by tracking the spectral region between 370 and 500 nm. Therefore, the presented results confirm that LIBS method enables an on-line monitoring needed for selective removal of thin layers by laser.

  14. Choroidal metastasis from leiomyosarcoma in two cases

    Directory of Open Access Journals (Sweden)

    Eric Feinstein

    2014-01-01

    Full Text Available Leiomyosarcoma is a malignant tumor of mesenchymal cells and is the most common soft-tissue sarcoma. Leiomyosarcoma is a notably rare tumor in the ophthalmic region and can be of primary, secondary or metastatic origin. To the best of our knowledge, there has only been one published case of leiomyosarcoma metastasis to the choroid. In this case study, we report two cases of primary leiomyosarcoma with metastasis to the choroid of the eye. Both cases displayed systemic metastasis and showed response to high dose plaque radiotherapy. Despite its prevalence as the leading form of sarcoma, leiomyosarcoma rarely metastasizes to the ocular region.

  15. Natural course of symptomatic focal choroidal excavation.

    Science.gov (United States)

    Pierro, Luisa; Casalino, Giuseppe; Introini, Ugo; Gagliardi, Marco; Sergenti, Jessica; Cascavilla, Maria Lucia; Bandello, Francesco

    2015-01-01

    A 32-year-old man was referred to the authors' department for nonspecified macular dystrophy with persistent metamorphopsia in the right eye diagnosed 10 years before and followed using optical coherence tomography. The patient underwent a comprehensive ocular examination, including multimodal imaging evaluation and electrofunctional testing. The diagnosis was consistent with nonconforming focal choroid excavation. Over 10 years, no complications occurred, visual acuity was stable, and optical coherence tomography showed no progression of the lesion during follow-up. In this case, nonconforming symptomatic focal choroid excavation was a nonprogressive condition with good long-term visual outcome. Copyright 2015, SLACK Incorporated.

  16. Focal Choroidal Excavation in Best Vitelliform Macular Dystrophy: Case Report.

    Science.gov (United States)

    Esfahani, Mohammad Riazi; Esfahani, Hamid Riazi; Mahmoudi, Alireza; Johari, Mohammad Karim; Hemati, Karim

    2015-05-01

    Focal choroidal excavation (FCE) was first reported as a choroidal posteriorly excavated zone without any scleral change. Choroidal excavation also divided into conforming and nonconforming type. Numerous reports demonstrated association between FCE and other disease such as choroidal neovascularization and central serous choroidoretinopathy. Here, we report a rare case of FCE in a patient with Best disease. The patient was diagnosed by spectoral domain optical coherence tomography (SD-OCT). To the best of our knowledge, our patient is the second report of choroidal excavation in Best vitelliform macular dystrophy.

  17. Optical scattering measurements of laser induced damage in the inrtaocular lens.

    NARCIS (Netherlands)

    Kruijt, B.; van den Berg, T.J.T.P.

    2012-01-01

    This study optically determines whether the amount of light scatter due to laser-induced damage to the intraocular lens (IOL) is significant in relation to normal straylight values in the human eye. Two IOLs with laser-induced damage were extracted from two donor eyes. Each IOL had 15 pits and/or

  18. In vivo Diagnosis of Cervical Intraepithelial Neoplasia Using 337-nm- Excited Laser-Induced Fluorescence

    Science.gov (United States)

    Ramanujam, N.; Mitchell, M. F.; Mahadevan, A.; Warren, S.; Thomsen, S.; Silva, E.; Richards-Kortum, R.

    1994-10-01

    Laser-induced fluorescence at 337-nm excitation was used in vivo to differentiate neoplastic [cervical intraepithelial neoplasia (CIN)], nonneoplastic abnormal (inflammation and human papilloma viral infection), and normal cervical tissues. A colposcope (low-magnification microscope used to view the cervix with reflected light) was used to identify 66 normal and 49 abnormal (5 inflammation, 21 human papilloma virus infection, and 23 CIN) sites on the cervix in 28 patients. These sites were then interrogated spectroscopically. A two-stage algorithm was developed to diagnose CIN. The first stage differentiated histologically abnormal tissues from colposcopically normal tissues with a sensitivity, specificity, and positive predictive value of 92%, 90%, and 88%, respectively. The second stage differentiated preneoplastic and neoplastic tissues from nonneoplastic abnormal tissues with a sensitivity, specificity, and positive predictive value of 87%, 73%, and 74%, respectively. Spectroscopic differences were consistent with a decrease in the absolute contribution of collagen fluorescence, an increase in the absolute contribution of oxyhemoglobin attenuation, and an increase in the relative contribution of reduced nicotinamide dinucleotide phosphate [NAD(P)H] fluorescence as tissue progresses from normal to abnormal in the same patient. These results suggest that in vivo fluorescence spectroscopy of the cervix can be used to diagnose CIN at colposcopy.

  19. Radioactive contamination screening with laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Sheely, R. [Oak Ridge K-25 Site, TN (United States); Di Benedetto, J. [EG and G Energy Measurements, Inc., Goleta, CA (United States). Santa Barbara Operations

    1994-06-01

    The ability to induce, detect and discriminate fluorescence of uranium oxides makes available new capabilities for screening the surface of large complex facilities for uranium. This paper will present the results of field tests evaluate laser-induced fluorescence (LIF) as a contamination screening tool and report on the progress to produce a field portable instrument for uranium surveys on exposed surfaces. The principal effect is to illuminate the surface of an object or an area with a remotely-located light source, and to evaluate the re-radiated emission energy. A gated intensified CCD camera was used with ultraviolet (UV) laser excitation to discriminate the phosphorescent (persistent) green uranium emission from the prompt background fluorescence which results from excitation of plants, concrete, soils, and other background materials.

  20. Laser-induced vibration of a thin soap film.

    Science.gov (United States)

    Emile, Olivier; Emile, Janine

    2014-09-21

    We report on the vibration of a thin soap film based on the optical radiation pressure force. The modulated low power laser induces a counter gravity flow in a vertical free-standing draining film. The thickness of the soap film is then higher in the upper region than in the lower region of the film. Moreover, the lifetime of the film is dramatically increased by a factor of 2. Since the laser beam only acts mechanically on the film interfaces, such a film can be employed in an optofluidic diaphragm pump, the interfaces behaving like a vibrating membrane and the liquid in-between being the fluid to be pumped. Such a pump could then be used in delicate micro-equipment, in chips where temperature variations are detrimental and even in biological systems.

  1. Theory of laser-induced demagnetization at high temperatures

    KAUST Repository

    Manchon, Aurelien

    2012-02-17

    Laser-induced demagnetization is theoretically studied by explicitly taking into account interactions among electrons, spins, and lattice. Assuming that the demagnetization processes take place during the thermalization of the subsystems, the temperature dynamics is given by the energy transfer between the thermalized interacting baths. These energy transfers are accounted for explicitly through electron-magnon and electron-phonon interactions, which govern the demagnetization time scale. By properly treating the spin system in a self-consistent random phase approximation, we derive magnetization dynamic equations for a broad range of temperature. The dependence of demagnetization on the temperature and pumping laser intensity is calculated in detail. In particular, we show several salient features for understanding magnetization dynamics near the Curie temperature. While the critical slowdown in dynamics occurs, we find that an external magnetic field can restore the fast dynamics. We discuss the implication of the fast dynamics in the application of heat-assisted magnetic recording.

  2. Printing biological solutions through laser-induced forward transfer

    Science.gov (United States)

    Duocastella, M.; Fernández-Pradas, J. M.; Domínguez, J.; Serra, P.; Morenza, J. L.

    2008-12-01

    Laser-induced forward transfer (LIFT) is a direct-writing technique adequate for the high-resolution printing of a wide range of materials, including biological molecules. In this article, the preparation through LIFT of microarrays of droplets from a solution containing rabbit antibody immunoglobulin G (IgG) is presented. The microarrays were prepared at different laser pulse energy conditions, obtaining microdroplets with a circular and well-defined contour. The transfer process has a double threshold: a minimum energy density required to generate an impulsion on the liquid film, and a minimum pulse energy, which corresponds to the onset for material ejection. In addition, it was demonstrated that the transfer process can be correctly described through a simple model which relates the energy density threshold with the amount of released material. Finally, a fluorescence assay was carried out in which the preservation of the activity of the transferred biomolecules was demonstrated.

  3. Laser-induced fluorescence spectroscopy in tissue local necrosis detection

    Science.gov (United States)

    Cip, Ondrej; Buchta, Zdenek; Lesundak, Adam; Randula, Antonin; Mikel, Bretislav; Lazar, Josef; Veverkova, Lenka

    2014-03-01

    The recent effort leads to reliable imaging techniques which can help to a surgeon during operations. The fluorescence spectroscopy was selected as very useful online in vivo imaging method to organics and biological materials analysis. The presented work scopes to a laser induced fluorescence spectroscopy technique to detect tissue local necrosis in small intestine surgery. In first experiments, we tested tissue auto-fluorescence technique but a signal-to-noise ratio didn't express significant results. Then we applied a contrast dye - IndoCyanine Green (ICG) which absorbs and emits wavelengths in the near IR. We arranged the pilot experimental setup based on highly coherent extended cavity diode laser (ECDL) used for stimulating of some critical areas of the small intestine tissue with injected ICG dye. We demonstrated the distribution of the ICG exciter with the first file of shots of small intestine tissue of a rabbit that was captured by high sensitivity fluorescent cam.

  4. Laser-induced stress transients: applications for molecular delivery

    Science.gov (United States)

    Flotte, Thomas J.; Lee, Shun; Zhang, Hong; McAuliffe, Daniel J.; Douki, Tina; Doukas, Apostolos G.

    1995-05-01

    Lasers can be used to enhance the delivery of a number of molecules. Other investigators have demonstrated local release of molecules from liposomes following laser irradiation, microbeam disruption of the cell membrane to increase cell transport, microbeam ablation of the zona pellucida surrounding the ovum to increase the chances of fertilization, and increased transcutaneous transport following ablation of the stratum corneum. Our experiments have shown that laser-induced stress transients can be utilized as a vector for intracellular delivery of molecules that may or may not normally cross the cell membrane. These two conditions have been tested with Photofrin and DNA. This technology may have applications in cell and molecular biology, cancer therapy, gene therapy, and others.

  5. Femtosecond laser induced phenomena in transparent solid materials

    DEFF Research Database (Denmark)

    Tan, D.Z.; Sharafudeen, K.N.; Yue, Yuanzheng

    2016-01-01

    parameters influencing the femtosecond laser interaction with transparent materials, and a brief description of various energy transfer processes in materials during femtosecond laser irradiation. The second part will give an account on various phenomena such as multiphoton excited upconversion luminescence......The interaction of intense femtosecond laser pulses with transparent materials is a topic that has caused great interest of scientists over the past two decades. It will continue to be a fascinating field in the coming years. This is because many challenging fundamental problems have not been......–matter interaction, and fabricate various integrated micro-devices. In recent years we have witnessed exciting development in understanding and applying femtosecond laser induced phenomena in transparent materials. The interaction of femtosecond laser pulses with transparent materials relies on non...

  6. Laser-induced micro-jetting from armored droplets

    KAUST Repository

    Marston, J. O.

    2015-06-23

    We present findings from an experimental study of laser-induced cavitation within a liquid drop coated with a granular material, commonly referred to as “armored droplets” or “liquid marbles.” The cavitation event follows the formation of plasma after a nanosecond laser pulse. Using ultra-high-speed imaging up to 320,610 fps, we investigate the extremely rapid dynamics following the cavitation, which manifests itself in the form of a plethora of micro-jets emanating simultaneously from the spaces between particles on the surface of the drop. These fine jets break up into droplets with a relatively narrow diameter range, on the order of 10 μm. © 2015, Springer-Verlag Berlin Heidelberg.

  7. Detection of early caries by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-07-01

    To improve sensitivity of dental caries detection by laser-induced breakdown spectroscopy (LIBS) analysis, it is proposed to utilize emission peaks in the ultraviolet. We newly focused on zinc whose emission peaks exist in ultraviolet because zinc exists at high concentration in the outer layer of enamel. It was shown that by using ratios between heights of an emission peak of Zn and that of Ca, the detection sensitivity and stability are largely improved. It was also shown that early caries are differentiated from healthy part by properly setting a threshold in the detected ratios. The proposed caries detection system can be applied to dental laser systems such as ones based on Er:YAG-lasers. When ablating early caries part by laser light, the system notices the dentist that the ablation of caries part is finished. We also show the intensity of emission peaks of zinc decreased with ablation with Er:YAG laser light.

  8. Analysis of fresco by laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Caneve, L., E-mail: luisa.caneve@enea.i [ENEA, CR Frascati, Via E. Fermi 45, 00044 Frascati (Italy); Diamanti, A. [Universita ' Tor Vergata' , Dipartimento di Scienze e Tecnologie Chimiche, via della Ricerca Scientifica 1, 00133 Roma (Italy); Grimaldi, F. [ENEA, CR Frascati, Via E. Fermi 45, 00044 Frascati (Italy); Palleschi, G. [Universita ' Tor Vergata' , Dipartimento di Scienze e Tecnologie Chimiche, via della Ricerca Scientifica 1, 00133 Roma (Italy); Spizzichino, V. [ENEA, CR Frascati, Via E. Fermi 45, 00044 Frascati (Italy); Valentini, F. [Universita ' Tor Vergata' , Dipartimento di Scienze e Tecnologie Chimiche, via della Ricerca Scientifica 1, 00133 Roma (Italy)

    2010-08-15

    The laser-based techniques have been shown to be a very powerful tool for artworks characterization and are used in the field of cultural heritage for the offered advantages of minimum invasiveness, in situ applicability and high sensitivity. Laser induced breakdown spectroscopy, in particular, has been applied in this field to many different kinds of ancient materials with successful results. In this work, a fragment of a Roman wall painting from the archaeological area of Pompeii has been investigated by LIBS. The sample elemental composition resulting from LIBS measurements suggested the presence of certain pigments. The ratio of the intensities of different lines related to some characteristic elements is proposed as an indicator for pigment recognition. The depth profiling permitted to put in evidence the presence of successive paint layers with different compositions. A comparison with the results obtained by the microscopy inspection of the sample has been done.

  9. Analysis of fresco by laser induced breakdown spectroscopy

    Science.gov (United States)

    Caneve, L.; Diamanti, A.; Grimaldi, F.; Palleschi, G.; Spizzichino, V.; Valentini, F.

    2010-08-01

    The laser-based techniques have been shown to be a very powerful tool for artworks characterization and are used in the field of cultural heritage for the offered advantages of minimum invasiveness, in situ applicability and high sensitivity. Laser induced breakdown spectroscopy, in particular, has been applied in this field to many different kinds of ancient materials with successful results. In this work, a fragment of a Roman wall painting from the archaeological area of Pompeii has been investigated by LIBS. The sample elemental composition resulting from LIBS measurements suggested the presence of certain pigments. The ratio of the intensities of different lines related to some characteristic elements is proposed as an indicator for pigment recognition. The depth profiling permitted to put in evidence the presence of successive paint layers with different compositions. A comparison with the results obtained by the microscopy inspection of the sample has been done.

  10. Recognition of archaeological materials underwater by laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lazic, V. [ENEA, FIS-LAS, V. E. Fermi 45, Frascati, RM (Italy)]. E-mail: lazic@frascati.enea.it; Colao, F. [ENEA, FIS-LAS, V. E. Fermi 45, Frascati, RM (Italy); Fantoni, R. [ENEA, FIS-LAS, V. E. Fermi 45, Frascati, RM (Italy); Spizzicchino, V. [ENEA, FIS-LAS, V. E. Fermi 45, Frascati, RM (Italy)

    2005-08-31

    The detection of different materials immersed in seawater has been studied by means of Laser Induced Breakdown Spectroscopy. The plasma emission was produced by a Q-Switched Nd:YAG laser operated at 1064 nm in a dual pulse mode. Different classes of materials potentially found in the undersea archaeological parks, such as iron, copper-based alloys, precious alloys, marble and wood have been examined. Data acquisition and processing were optimized for better signal control and in order to improve the detection threshold. In all the examined cases but wood, qualitative analysis was successful and allowed for the material recognition. The spectral features necessary to clearly distinguish marble materials from calcareous rocks have been also established. It was found that these characteristic spectral intervals could be also used for the recognition of sedimentary layers deposited on the underwater findings. Quantitative chemical analysis was also performed on submerged bronze samples, after generating calibration curves with standards of similar matrix composition.

  11. Laser-induced damage thresholds of starched PMMA waveplates

    Science.gov (United States)

    Melninkaitis, A.; Mikšys, D.; Maciulevičius, M.; Sirutkaitis, V.; Šlekys, G.; Samoylov, A. V.

    2007-01-01

    Polymethyl methacrylate (PMMA) is a versatile polymeric material that is well suited for fabrication of many commercial optical components: lenses, fibers, windows, phase waveplates and others. Our focus is achromatic zero-order waveplates made of anisotropic PMMA which can be used to modify the state of polarization of electromagnetic radiation. Such waveplates have a broad range of application in devices where polarized radiation is used. For example, when tunable lasers are used or when spectropolarimetric measurements are performed, one needs an achromatic waveplate providing a specific retardation in a wide wavelength range. Herewith anisotropic properties of PMMA subjected to one-axis stretching are analyzed and the technology for manufacturing such achromatic and super-achromatic, one-axis-stretched PMMA waveplates is described. This technology excludes any mechanical processing of waveplate component surfaces. Technical characteristics of achromatic and super-achromatic waveplates manufactured of PMMA including results of laser-induced damage threshold (LIDT) measurements are discussed below.

  12. Study of laser-induced cavitation bubble in liquid nitrogen

    Science.gov (United States)

    Takahashi, Toshimasa; Hisano, Eizo; Toyada, Kazuhiro; Maeno, Kazuo

    2005-03-01

    The behavior of Vapor bubbles in cryogenic liquid is regarded as a cryogenic and phase-changing flow field, where instability of bubble surface becomes larger than those in normal temperature liquid as water or oil, since the cryogenic liquid has characteristic feature of small latent heat, surface tension, and viscosity. The cavitation phenomena in cryogenic temperature range are regarded as vacitation in the liquid of near-boiling point. The cryogenic cavitation, however, have a significant influence on solid surfaces due to their weakness in cryogenic range. In this paper, shock waves discharged from a pulse-laser induced bubble and behavior of the bubble are experimentally investigated. Pulsed YAG laser is used to produce a bubble in cryogenic liquid nitrogen, and shock waves are visualized by using a digital still camera with schlieren method.

  13. Laser-induced breakdown spectroscopy theory and applications

    CERN Document Server

    Perini, Umberto

    2014-01-01

    This book deals with the Laser-Induced Breakdown Spectroscopy (LIBS), a widely used atomic emission spectroscopy technique for elemental analysis of materials. It is based on the use of a high-power, short pulse laser excitation. The book is divided into two main sections: the first one concerning theoretical aspects of the technique, the second one describing the state of the art in applications of the technique in different scientific/technological areas. Numerous examples of state of the art applications provide the readers an almost complete scenario of the LIBS technique. The LIBS theoretical aspects are reviewed. The book helps the readers who are less familiar with the technique to understand the basic principles. Numerous examples of state of the art applications give an almost complete scenario of the LIBS technique potentiality. These examples of applications may have a strong impact on future industrial utilization. The authors made important contributions to the development of this field.

  14. Investigation of the laser-induced damage of dispersive coatings

    Science.gov (United States)

    Angelov, Ivan B.; von Conta, Aaron; Trushin, Sergei A.; Major, Zsuzsanna; Karsch, Stefan; Krausz, Ferenc; Pervak, Vladimir

    2011-12-01

    Different dispersive coatings were tested in terms of laser-induced damage threshold by using a Ti:Sapphire laser yielding 1 mJ, 30 fs pulses at 500 Hz repetition rate at 790 nm central wavelength. The beam was focused down to 140 μm. Single layer coatings of Au, Ag, Nb2O5, SiO2, Ta2O5 and mixtures of Ta2O5 and silica were examined as well as different dispersive coatings. We observed a direct dependence of the damage threshold on the band gap of the materials used to produce the different samples. The damage threshold values for the dispersive coatings employing the same high index material lay within a range of 30% of each other.

  15. Laser-induced breakdown spectroscopy fundamentals and applications

    CERN Document Server

    Noll, Reinhard

    2012-01-01

    This book is a comprehensive source of the fundamentals, process parameters, instrumental components and applications of laser-induced breakdown spectroscopy (LIBS). The effect of multiple pulses on material ablation, plasma dynamics and plasma emission is presented. A heuristic plasma modeling allows to simulate complex experimental plasma spectra. These methods and findings form the basis for a variety of applications to perform quantitative multi-element analysis with LIBS. These application potentials of LIBS have really boosted in the last years ranging from bulk analysis of metallic alloys and non-conducting materials, via spatially resolved analysis and depth profiling covering measuring objects in all physical states: gaseous, liquid and solid. Dedicated chapters present LIBS investigations for these tasks with special emphasis on the methodical and instrumental concepts as well as the optimization strategies for a quantitative analysis. Requirements, concepts, design and characteristic features of LI...

  16. Laser-induced single point nanowelding of silver nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Shuowei; Li, Qiang, E-mail: qiangli@zju.edu.cn; Liu, Guoping; Yang, Hangbo; Yang, Yuanqing; Zhao, Ding; Wang, Wei; Qiu, Min, E-mail: minqiu@zju.edu.cn [State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2016-03-21

    Nanowelding of nanomaterials opens up an emerging set of applications in transparent conductors, thin-film solar cells, nanocatalysis, cancer therapy, and nanoscale patterning. Single point nanowelding (SPNW) is highly demanded for building complex nanostructures. In this letter, the precise control of SPNW of silver nanowires is explored in depth, where the nanowelding is laser-induced through the plasmonic resonance enhanced photothermal effect. It is shown that the illumination position is a critical factor for the nanowelding process. As an example of performance enhancement, output at wire end can be increased by 65% after welding for a plasmonic nanocoupler. Thus, single point nanowelding technique shows great potentials for high-performance electronic and photonic devices based on nanowires, such as nanoelectronic circuits and plasmonic nanodevices.

  17. Laser-induced incandescence: Towards quantitative soot volume fraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tzannis, A.P.; Wienbeucker, F.; Beaud, P.; Frey, H.-M.; Gerber, T.; Mischler, B.; Radi, P.P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Laser-Induced Incandescence has recently emerged as a versatile tool for measuring soot volume fraction in a wide range of combustion systems. In this work we investigate the essential features of the method. LII is based on the acquisition of the incandescence of soot when heated through a high power laser pulse. Initial experiments have been performed on a model laboratory flame. The behaviour of the LII signal is studied experimentally. By applying numerical calculations we investigate the possibility to obtain two-dimensional soot volume fraction distributions. For this purpose a combination of LII with other techniques is required. This part is discussed in some extent and the future work is outlined. (author) 4 figs., 3 refs.

  18. Inexpensive laser-induced surface modification in bismuth thin films

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, A. Reyes [Facultad de Ciencias, Universidad Autónoma del Estado de México, Carretera Toluca, Ixtlahuaca Kilómetro 15.5, C.P. 50200 Edo. de México (Mexico); Hautefeuille, M., E-mail: mathieu_h@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Exterior S/N, Coyoacán, Ciudad Universitaria, C.P. 04510 D.F. Mexico (Mexico); García, A. Esparza [Fotofísica y Películas Delgadas, Departamento de Tecnociencias, CCADET-UNAM, Circuito exterior s/n C.P. 04510 Cd. Universitaria, D.F. Mexico (Mexico); Mejia, O. Olea [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, Km 14.5, Unidad El Rosedal, 50200 San Cayetano, Estado de México (Mexico); López, M.A. Camacho [Facultad de Química, Universidad Autónoma del Estado de México, Tollocan s/n, esq. Paseo Colón, Toluca, Estado de México 50110 (Mexico)

    2015-05-01

    Highlights: • Laser-induced microbumps were formed on bismuth films using a simple, low-cost, laser setup. • The patterns, similar to those typically obtained with high-power lasers, were characterized. • Control of laser ablation conditions is critical in the fabrication of surface microbumps. - Abstract: In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD–DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters.

  19. Hot spin spots in the laser-induced demagnetization

    Directory of Open Access Journals (Sweden)

    M. S. Si

    2012-03-01

    Full Text Available Laser-induced femtosecond magnetism or femtomagnetism simultaneously relies on two distinctive contributions: (a the optical dipole interaction (ODI between a laser field and a magnetic system and (b the spin expectation value change (SEC between two transition states. Surprisingly, up to now, no study has taken both contributions into account simultaneously. Here we do so by introducing a new concept of the optical spin generator, a product of SEC and ODI between transition states. In ferromagnetic nickel, our first-principles calculation demonstrates that the larger the value of optical spin generator is, the larger the dynamic spin moment change is. This simple generator directly links the time-dependent spin moment change ΔMzk(t at every crystal-momentum k point to its intrinsic electronic structure and magnetic properties. Those hot spin spots are a direct manifestation of the optical spin generator, and should be the focus of future research.

  20. Torpedo Maculopathy Associated with Choroidal Neovascularization.

    Science.gov (United States)

    Jurjevic, D; Böni, C; Barthelmes, D; Fasler, K; Becker, M; Michels, S; Stemmle, J; Herbort, C; Zweifel, S A

    2017-04-01

    Background Torpedo maculopathy is a very rare, congenital, usually unilateral hypopigmented lesion in the temporal macula. Material and Methods This retrospective case series describes three patients with torpedo maculopathy. Results The first two cases demonstrate typical clinical and imaging findings of torpedo maculopathy in asymptomatic patients. The third case relates to a symptomatic young patient with a torpedo lesion, a smaller satellite lesion, and evidence of choroidal neovascularization confirmed by fluorescence angiography. In the area of the clinically visible torpedo lesion, spectral domain optical coherence tomography showed atrophy of the outer retina with increased choroidal signalling and a hyperreflective lesion above the retinal pigment epithelium suggestive of choroidal neovascularization. Fundus autofluorescence imaging revealed a hyperautofluorescent rim along the margin of the hypoautofluorescent torpedo lesion. Conclusion In the literature, torpedo lesions are usually regarded as benign lesions with no tendency for progression. The third case demonstrates that torpedo lesions may be associated with choroidal neovascularization, which has been successfully treated with anti-VEGF therapy. Georg Thieme Verlag KG Stuttgart · New York.

  1. Choroid plexus tumors in pediatric patients.

    Science.gov (United States)

    Ogiwara, Hideki; Dipatri, Arthur J; Alden, Tord D; Bowman, Robin M; Tomita, Tadanori

    2012-02-01

    Choroid plexus tumors are rare intraventricular tumors, accounting for less than 1% of all intracranial tumors and 2-4% of brain tumors in children. The authors present their experience in the management of these lesions, and a review of the literature is performed. We retrospectively analyzed the outcome of pediatric patients with choroid plexus tumors treated with surgical resection. The patients' charts were reviewed for demographic data, clinical presentation, surgical therapy and follow-up. This study involves 18 consecutive choroid plexus tumors: 14 papillomas, 2 atypical papillomas and 2 carcinomas. The tumor was located in the lateral ventricles (12), the fourth ventricle (4) and the third ventricle (2). The mean age at presentation was 4.6 years. Surgical resection was performed in all cases and no patients died perioperatively. Survival rate of papilloma patients was 100% without evidence of recurrent disease (mean follow-up for 73 months). Survival rate of carcinoma patients was 50% (mean follow-up for 23.5 months). One carcinoma patient died of disseminated disease 13 months after surgery. The functional outcome in long-term survivors after papilloma surgery was excellent. Postoperative extraventricular drainage (EVD) was performed in 12 patients. Five patients (27.8%) had persistent hydrocephalus after tumor resection and required a ventriculoperitoneal shunt. Choroid plexus papilloma is a surgically curable disease. Postoperative EVD was considered effective in lowering the rate of shunt requirement through releasing the blood-tinged CSF and small particles of tumor residue.

  2. Endoscopic third ventriculostomy and choroid plexus cauterization ...

    African Journals Online (AJOL)

    Background: Endoscopic third ventriculostomy (ETV) and Choroid Plexus Cauterization (CPC) have been recommended as reliable surgical options in developing countries for childhood hydrocephalus owing to reported shunt failures in shunt dependency. Objective: To evaluate outcomes of the ETV and ETV-CPC ...

  3. Transpupillary Thermotherapy for Classic Subfoveal Choroidal ...

    African Journals Online (AJOL)

    exudative age-related macular degeneration OS with bilateral cataracts and primary open angle glaucoma OU was made. Complete resolution of the choroidal neovascular membrane was achieved with transpupillary thermotherapy. Keywords: transpupillary thermotherapy, age-related macular degeneration, subfoveal ...

  4. Transpupillary Thermotherapy for Classic Subfoveal Choroidal ...

    African Journals Online (AJOL)

    Dr. Oderinlo

    exudative age-related macular degeneration OS with bilateral cataracts and primary open angle glaucoma OU was made. Complete resolution of the choroidal neovascular membrane was achieved with transpupillary thermotherapy. Key words: transpupillary thermotherapy, age-related macular degeneration, subfoveal ...

  5. Single intravitreal ranibizumab for myopic choroidal neovascularization.

    Science.gov (United States)

    Nor-Masniwati, Saidin; Shatriah, Ismail; Zunaina, Embong

    2011-01-01

    We report a case of myopic choroidal neovascularization that showed improvement after a single injection of ranibizumab. A 45-year-old Chinese man with high myopia presented with sudden onset painless central scotoma of his right eye of 2 weeks' duration. There was no history of trauma. His right eye vision on presentation was 6/30 which showed no improvement with pinhole. The right fundus showed myopic maculopathy at the posterior pole with subretinal hemorrhage at the inferotemporal fovea. The optic disc was tilted with inferotemporal peripapillary atrophy. There was a myopic maculopathy appearance in the macula of the left eye. Fundus fluorescein angiography revealed choroidal neovascularization at the fovea of the right eye. A diagnosis of right eye choroidal neovascularization secondary to myopic maculopathy was made. A single intravitreal injection of ranibizumab 0.05 mL was given. Ten weeks following intravitreal injection, vision had improved to 6/7.5, and repeated fundus fluorescein angiography showed absence of choroidal neovascularization. Follow-up at 6 months showed visual acuity had normalized to 6/6 with glasses, which was maintained up to 12 months following treatment. The right fundus showed no further subretinal hemorrhage with no new lesions.

  6. Transpupillary thermotherapy (TTT) in circumscribed choroidal hemangioma.

    Science.gov (United States)

    Fuchs, Anne V; Mueller, Arthur J; Grueterich, Martin; Ulbig, Michael W

    2002-01-01

    Choroidal hemangioma presents a therapeutic dilemma. Although it is a benign tumor, it may lead to massive exudation of subretinal fluid and a loss of visual function. Argon laser photo-coagulation in a grid pattern may be followed by initial absorption of subretinal fluid, but recurrence is common. Trans-scleral cryotherapy is difficult to apply at the posterior pole of the eye. External beam irradiation may bear a risk of maculopathy and papillopathy. Brachytherapy does not allow placement of radiation to the hemangioma sparing other retinal or choroidal structures. We sought to determine whether transpupillary thermotherapy (TTT) is suitable for treatment of choroidal hemangioma at the posterior pole. We present ten patients with choroidal hemangioma. All of these received TTT. The mean follow-up period was 13.3 months (3-21 months). TTT was delivered via a slitlamp microscope with a diode laser at 810 nm. After TTT, reduction in tumor prominence was observed in eight patients at 3 months after treatment by A scan sonography. Visual acuity improved by more than three lines in four patients, and remained unchanged in all other patients. Two patients were retreated to achieve complete absorption of fluid. Serous retinal detachment persisted in three patients because the hemangioma could not be treated completely because of proximity to the fovea. Our preliminary results suggest that TTT may be used effectively to treat some choroidal hemangiomas in the first instance and prevent fluid leakage provided the lesion does not involve the fovea. However, long-term follow-up and more cases are needed to evaluate the long-term visual outcome and potential risks.

  7. Digital imaging in differential diagnosis of small choroidal melanoma.

    Science.gov (United States)

    Saari, Jukka M; Kivelä, Tero; Summanen, Paula; Nummelin, Kari; Saari, K Matti

    2006-12-01

    To assess the role of digital imaging and a new subtraction method for differential diagnosis of choroidal nevus and small choroidal melanoma. Of 241 consecutive patients referred to a tertiary referral center for suspected choroidal melanoma, 110 who underwent digital imaging of the ocular fundus were eligible for this study. Digital color, red-free and red light retinal images were evaluated in a randomized and masked manner and by the subtraction method for diagnosis of the fundus lesion. The reference standard was based on the combined results of ophthalmological examination, including mydriatic ophthalmoscopy, B scan ultrasonography, digital imaging and fluorescein angiography of the ocular fundus. Comparative use of digital color, red-free and red light imaging had 85.7% (95%CI 42.1-99.6) sensitivity, 99.0% (95%CI 94.7-99.9) specificity and 98.2% (95%CI 93.6-99.8) exact agreement versus reference standard in differentiation of small choroidal melanoma from pseudomelanoma. Direct comparison between use of digital images and the reference standard showed excellent agreement in detecting small choroidal melanoma from suspected choroidal lesions (K 0.847; 95%CI 0.639-1.0). The subtraction method was useful to show growth in four of 94 melanocytic choroidal tumors. The mean annual incidence of choroidal melanoma in Southwest Finland was 0.80 per 100.000 population. The most frequent choroidal pseudomelanomas were choroidal melanotic and amelanotic nevi, disciform lesions, congenital hypertrophy of the retinal pigment epithelium, and circumscribed choroidal hemangioma. Combined use of digital color, red-free and red light imaging was a suitable adjunct in differentiation of small choroidal melanoma from different pseudomelanomas. The subtraction method may reveal early growth of the melanotic choroidal tumors.

  8. Stress-induced stimulation of choline transport in cultured choroid plexus epithelium exposed to low concentrations of cadmium

    Science.gov (United States)

    Young, Robin K.

    2013-01-01

    The choroid plexus epithelium forms the blood-cerebrospinal fluid barrier and accumulates essential minerals and heavy metals. Choroid plexus is cited as being a “sink” for heavy metals and excess minerals, serving to minimize accumulation of these potentially toxic agents in the brain. An understanding of how low doses of contaminant metals might alter transport of other solutes in the choroid plexus is limited. Using primary cultures of epithelial cells isolated from neonatal rat choroid plexus, our objective was to characterize modulation of apical uptake of the model organic cation choline elicited by low concentrations of the contaminant metal cadmium (CdCl2). At 50–1,000 nM, cadmium did not directly decrease or increase 30-min apical uptake of 10 μM [3H]choline. However, extended exposure to 250–500 nM cadmium increased [3H]choline uptake by as much as 75% without marked cytotoxicity. In addition, cadmium induced heat shock protein 70 and heme oxygenase-1 protein expression and markedly induced metallothionein gene expression. The antioxidant N-acetylcysteine attenuated stimulation of choline uptake and induction of stress proteins. Conversely, an inhibitor of glutathione synthesis l-buthionine-sulfoximine (BSO) enhanced stimulation of choline uptake and induction of stress proteins. Cadmium also activated ERK1/2 MAP kinase. The MEK1 inhibitor PD98059 diminished ERK1/2 activation and attenuated stimulation of choline uptake. Furthermore, inhibition of ERK1/2 activation abated stimulation of choline uptake in cells exposed to cadmium with BSO. These data indicate that in the choroid plexus, exposure to low concentrations of cadmium may induce oxidative stress and consequently stimulate apical choline transport through activation of ERK1/2 MAP kinase. PMID:24401988

  9. The Chinese medicine formula HB01 reduces choroidal neovascularization by regulating the expression of vascular endothelial growth factor

    Directory of Open Access Journals (Sweden)

    Jin Ming

    2012-06-01

    Full Text Available Abstract Background Choroidal neovascularization (CNV remains the leading cause of newly acquired blindness in the developed world. Currently anti-vascular endothelial growth factor (VEGF therapies are broadly used to treat neovascular ocular disorders. Here we demonstrate the effect of a traditional Chinese medicine formula, HB01, on CNV. Methods A rat model of laser-induced CNV was used to investigate the effect of HB01 in vivo. The CNV lesions in the eye were evaluated using fundus fluorescein angiography and visualized/quantified using confocal microscopy. Expression of VEGF in the choroidal and retinal tissues was measured using quantitative real-time PCR and immunohistochemistry. Results We demonstrated that a traditional Chinese Medicine formula, named HB01, significantly reduced neovascularization in a rat CNV model. The effect of HB01 on CNV was comparable to the intravitreal injection of bevacizumab (Avastin. Our results also suggested that HB01 may reduce CNV partially through inhibiting the expression of VEGF. Conclusions These data support HB01 as an alternative therapy for ocular neovascular disorders.

  10. Laser induced damage of fused silica polished optics due to a droplet forming organic contaminant

    Energy Technology Data Exchange (ETDEWEB)

    Bien-Aime, Karell; Neauport, Jerome; Tovena-Pecault, Isabelle; Fargin, Evelyne; Labrugere, Christine; Belin, Colette; Couzi, Michel

    2009-04-20

    We report on the effect of organic molecular contamination on single shot laser induced damage density at the wavelength of 351 nm, with a 3 ns pulse length. Specific contamination experiments were made with dioctylphthalate (DOP) in liquid or gaseous phase, on the surface of fused silica polished samples, bare or solgel coated. Systematic laser induced damage was observed only in the case of liquid phase contamination. Different chemical and morphological characterization methods were used to identify and understand the damage process. We demonstrate that the contaminant morphology, rather than its physicochemical nature, can be responsible for the decrease of laser induced damage threshold of optics.

  11. In Vitro Effect of Laser-Induced Hydrodynamics on Cancer Cells.

    Science.gov (United States)

    Elagin, V V; Pavlikov, A I; Yusupov, V I; Shirmanova, M V; Zagaynova, E V; Bagratashvili, V N

    2015-11-01

    We studied the effect of laser-induced hydrodynamic on viability of Colo-26 murine colon carcinoma cells in vitro. Laser-induced hydrodynamics was generated by a laser (λ=1.56 μ, power 3 W, 5 min exposure); to this end, the fiber end was submersed into a buffer above the cell monolayer. It was found that laser-induced hydrodynamics destructed the monolayer at standoff distances of between the working end of the laser fiber to cell monolayer of 1 and 5 mm and triggers apoptotic and necrotic death in remaining cells at a distance of 4 mm from the emitter.

  12. Laser-induced forward transfer (LIFT) of congruent voxels

    Energy Technology Data Exchange (ETDEWEB)

    Piqué, Alberto, E-mail: pique@nrl.navy.mil [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Kim, Heungsoo; Auyeung, Raymond C.Y.; Beniam, Iyoel [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Breckenfeld, Eric [National Research Council Fellow at the Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-06-30

    Highlights: • Laser-induced forward transfer (LIFT) is demonstrated with high viscosity Ag nanopaste. • Under the right conditions (viscosity and fluence) the transfer of congruent voxels was achieved. • For viscosities under 100 Pa s, congruent voxel transfer of silver nano-suspensions is only possible under a very narrow range of conditions. • For viscosities over 100 Pa s, congruent voxel transfer of silver nano-pastes works over a wider range of fluences, donor substrate thickness, gap distances and voxel areas. • The laser transfer of congruent voxels can be used for printing electronic patterns in particular interconnects. - Abstract: Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D

  13. Remodelling of choroidal blood flow in radiation choroidopathy

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Hideo; Muraoka, Kanemitsu; Takahashi, Kyoichi; Sutoh, Noriko [Gunma Univ., Maebashi (Japan). School of Medicine

    1997-02-01

    Two males, aged 68 and 34 years each, presented with radiation retinopathy. One had received radiation therapy to the whole brain for intracranial metastasis of lung carcinoma 29 months before. The other underwent surgery and radiation for melanoma of the upper eyelid 15 years before. When examined by indocyanine green angiography. both cases showed vasoocclusive changes in the choroid involving the choriocapillaris and major vessels in the affected fundus area. In one eye with severe retinal vascular lesions in the superior temporal quadrant, the vortex vein in the quadrant had obliterated. The venous blood in this quadrant was drained into the inferior temporal vortex vein crossing the presumed watershed zone temporal to the macula. Collaterals had formed between choroidal arteries and between choroidal veins. These cases illustrate that choroidal vascular lesions may be present in radiation retinopathy, that the former may be more pronounced than the latter and that choroidal vessels may undergo extensive remodelling to compensate for the disturbed choroidal circulation. (author)

  14. CT of malignant choroidal melanoma - morphology and perfusion characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Heller, M.; Hagemann, J.; Jend, H.H.; Guthoff, R.

    1982-03-01

    The computed tomographic morphology of malignant choroidal melanoma and its perfusion characteristics are described. Thirty-three static and serial CT examinations made on 29 patients with choroidal melanoma, three with pseudotumors of the macula and one with choroidal metastasis revealed the choroidal melanoma to be usually a hyperdense, markedly perfused tumor, while the non-contrast, diagnostically undifferentiable pseudotumors and the choroidal metastasis, revealed no significant change in density after the administration of contrast material. Density values or perfusion characteristics of choroidal melanoma that are outside of the normal range are a result of secondary changes within the immediate surroundings of the tumor, such as detachment of the retina, tumor-induced glaucoma, or tumor necrosis.

  15. Choroidal thickness evaluation in paediatric patients with adenotonsillar hypertrophy.

    Science.gov (United States)

    Yenigun, A; Elbay, A; Hafiz, A M; Ozturan, O

    2017-09-01

    To investigate choroidal thickness using enhanced-depth imaging optical coherence tomography in paediatric patients with adenotonsillar hypertrophy, with comparison to healthy children, three months after adenotonsillectomy. The patients were assigned to three groups: an adenotonsillar hypertrophy group, an adenotonsillectomy group and a healthy control group. In all groups, subfoveal, temporal and nasal choroidal thickness measurements were taken. In the subfoveal, temporal and nasal regions, choroidal tissue was found to be significantly thinner in adenotonsillar hypertrophy children than healthy children (p = 0.012, p = 0.027 and p = 0.020). The subfoveal and temporal choroidal thickness measurements of adenotonsillar hypertrophy group cases were significantly decreased compared to those in the adenotonsillectomy group (p = 0.038 and p = 0.048). There was a significant association between decreased choroidal thickness and adenotonsillar hypertrophy. Adenotonsillar hypertrophy may play an important role in decreased choroidal thickness.

  16. Choroid Melanoma Metastasis to Spine: A Rare Case Report

    Directory of Open Access Journals (Sweden)

    Hiren Mandaliya

    2016-01-01

    Full Text Available Metastatic choroid melanoma is a highly malignant disease with a limited life expectancy. The liver is the most common site for metastasis of uveal melanoma followed by lung, bone, skin, and subcutaneous tissue. Metastasis from choroidal melanoma usually occurs within the first five years of treatment for primary tumours. Metastatic choroid melanoma to the spine/vertebrae is extremely rare. We report the first case of spinal metastasis from choroid melanoma in a 61-year-old man who had been treated for primary ocular melanoma three years earlier with radioactive plaque brachytherapy. Synchronously, at the time of metastasis, he was also diagnosed as having a new primary lung adenocarcinoma as well. The only other case reported on vertebral metastasis from malignant melanoma of choroid in literature in which primary choroid melanoma was enucleated.

  17. Focal choroidal excavation in eyes with central serous chorioretinopathy.

    Science.gov (United States)

    Ellabban, Abdallah A; Tsujikawa, Akitaka; Ooto, Sotaro; Yamashiro, Kenji; Oishi, Akio; Nakata, Isao; Miyake, Masahiro; Akagi-Kurashige, Yumiko; Ueda-Arakawa, Naoko; Arichika, Shigeta; Yoshitake, Shin; Takahashi, Ayako; Yoshimura, Nagahisa

    2013-10-01

    To study the prevalence and 3-dimensional (3-D) tomographic features of focal choroidal excavations in eyes with central serous chorioretinopathy (CSC) using swept-source optical coherence tomography (OCT). Prospective, cross-sectional study. We examined 116 consecutive eyes with CSC with a prototype 3-D swept-source OCT. 3-D images of the shape of the macular area, covering 6 × 6 mm(2), were reconstructed by segmentation of the outer surface of the retinal pigment epithelium (RPE). The 3-D swept-source OCT detected focal choroidal excavations in 9 eyes (7.8%). The 3-D scanning protocol, coupled with en face scans, allowed for clear visualization of the excavation morphology. In 5 eyes with focal excavations, unusual choroidal tissue was found beneath the excavation, bridging the bottom of the excavation and the outer choroidal boundary. Additionally, 3 of those 5 eyes showed a suprachoroidal space below the excavation, as if the outer choroidal boundary is pulled inward by this bridging tissue. The focal choroidal excavations were located within fluorescein leakage points and areas of choroidal hyperpermeability. Eyes with focal choroidal excavations were more myopic (-4.42 ± 2.92 diopters) than eyes without excavations (-0.27 ± 1.80 diopters, P = .001). Subfoveal choroidal thickness was significantly thinner (301.3 ± 60.1 μm) in eyes with focal excavations than in eyes without the excavations (376.6 ± 104.8 μm, P = .036). Focal choroidal excavations were present in 7.8% of eyes with CSC. In these eyes, focal choroidal excavations may have formed from RPE retraction caused by focal scarring of choroidal connective tissue. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Oral Propranolol for Circumscribed Choroidal Hemangioma

    Directory of Open Access Journals (Sweden)

    Empar Sanz-Marco

    2011-02-01

    Full Text Available Introduction: Several therapeutic approaches have been developed to treat choroidal hemangioma. However, all these therapies are associated with a potential risk of damaging the overlying retina. Case Report: We report a case of circumscribed choroidal hemangioma (CCH in a 59-year-old man refractory to laser treatment. Visual acuity was 20/200 and a serous macular detachment was present. The CCH was treated with oral propanolol, whereupon visual acuity improved to 20/20 and the macular detachment resolved without systemic or local adverse effects. Discussion: Propanolol is a β-blocker commonly used in cardiology that may induce endothelium vasoconstriction and inhibit endothelial proliferation. It has been shown to be effective in infantile facial hemangiomas, and proved safe and effective for the CCH in our patient. Further studies are needed to confirm our observation.

  19. Focal choroidal excavation associated with focal retinochoroiditis.

    Science.gov (United States)

    Ohki, Tetsutaro; Sakai, Tsutomu; Tsuneoka, Hiroshi

    2015-01-01

    To describe detailed spectral-domain optical coherence tomography (OCT) findings for two patients with focal choroidal excavation (FCE) associated with focal retinochoroiditis. Three eyes from two patients with FCE associated with focal retinochoroiditis were evaluated by funduscopy, fluorescence angiography, indocyanine green angiography, and spectral-domain OCT during follow-up. Both patients with focal retinochoroiditis developed new FCE after oral steroid treatment and two eyes showed regression of the FCE during the follow-up. Both eyes from one patient transformed from the conforming to the nonconforming type and neither of the eyes were stable during the follow-up. Ultimately, all eyes exhibited the conforming-type FCE. Focal choroidal excavation can be seen as a tomographic phenotype after the treatment of focal retinochoroiditis. Spectral-domain OCT was useful for detecting the development of FCE after the treatment and for observing FCE regression.

  20. Symptomatic bilateral xanthogranuloma of the choroid plexus

    Directory of Open Access Journals (Sweden)

    Selin Tural Emon

    2017-01-01

    Full Text Available Xanthogranulomas (XGRs of the choroid plexus are rare, asymptomatic, and benign lesions usually found incidentally. Here, we present a case of a 47-year-old male with bilateral XGR of the choroid plexus with periventricular edema and discuss our case in relation to a review of existing literature pertaining to the radiology of XGRs. To the best of our knowledge, this is the first reported case of bilateral trigonal XGR causing brain edema without ventricular dilatation. Despite the fact that they can cause hydrocephalus, XGRs are silent and benign lesions. Although the etiopathology of XGRs remains poorly understood, enhanced imaging analyses may provide additional information regarding edema and focal white matter signal changes.

  1. Oral Propranolol for Circumscribed Choroidal Hemangioma

    Science.gov (United States)

    Sanz-Marco, Empar; Gallego, Roberto; Diaz-Llopis, Manuel

    2011-01-01

    Introduction Several therapeutic approaches have been developed to treat choroidal hemangioma. However, all these therapies are associated with a potential risk of damaging the overlying retina. Case Report We report a case of circumscribed choroidal hemangioma (CCH) in a 59-year-old man refractory to laser treatment. Visual acuity was 20/200 and a serous macular detachment was present. The CCH was treated with oral propanolol, whereupon visual acuity improved to 20/20 and the macular detachment resolved without systemic or local adverse effects. Discussion Propanolol is a β-blocker commonly used in cardiology that may induce endothelium vasoconstriction and inhibit endothelial proliferation. It has been shown to be effective in infantile facial hemangiomas, and proved safe and effective for the CCH in our patient. Further studies are needed to confirm our observation. PMID:21475606

  2. Standoff high energy laser induced oxidation spectroscopy (HELIOS)

    Science.gov (United States)

    Daigle, J.-F.; Pudo, D.; Théberge, F.

    2017-11-01

    High Energy Lasers (HELs) used for defense applications require operational distances ranging from few hundred meters to several kilometers. As the distance increases, the incident beam properties and, consequently, the anticipated effect delivered to the sample become less predictable. Therefore, the direct observation of the event induced by the laser can become an asset. In this paper, we propose a novel spectroscopic method that analyses in real time the spectral components present in the flames produced during the interaction of a HEL with a metallic piece at a long distance. This method was used on aluminum and carbon steel samples placed 200 m away from the laser system. It was discovered that the aluminum and iron oxides created as a by-product of the HEL reaction with the samples emitted clear fingerprint signatures that could be detected remotely using a spectroscopic receiver placed beside the HEL beam director. The real-time assessment of the laser-induced effect can be achieved by monitoring the temporal evolution of the oxide signatures, hence providing information to the operator about the reaction and the nature of the sample illuminated.

  3. Laser-induced electron diffraction for dynamic imaging of molecules

    Science.gov (United States)

    Lin, Chii-Dong

    2017-04-01

    Electron diffraction is the well-established tool for probing the structure of gas-phase molecules near the equilibrium geometry. To study chemical dynamics ultrashort electron pulses below a few tens of femtoseconds are needed. Laser-induced electron diffraction (LIED) is a method where molecules can be probed with femtosecond temporal resolution and sub-angstrom spatial resolution. In LIED, molecules are exposed to an intense femtosecond laser pulse. The electrons that have been previously removed by the laser field can be driven back later to rescatter with the parent molecular ion. Using diffraction images from large-angle backscattered events, sub-angstrom spatial resolution can be achieved with tens to hundreds eV electrons. Recent LIED experimental results showing bond breaking in molecules will be illustrated. Practical issues related to the retrieval of diffraction images from LIED on aligned molecules and possibilities of real-time imaging of dissociating molecules using LIED will be presented. US Department of Energy. This work is performed in collaboration with Anh Thu Le (Kansas State University) and the experimental group of Jens Biegert (ICFO, Barcelona).

  4. Laser-induced breakdown spectroscopy combined with spatial heterodyne spectroscopy.

    Science.gov (United States)

    Gornushkin, Igor B; Smith, Ben W; Panne, Ulrich; Omenetto, Nicoló

    2014-01-01

    A spatial heterodyne spectrometer (SHS) is tested for the first time in combination with laser-induced breakdown spectroscopy (LIBS). The spectrometer is a modified version of the Michelson interferometer in which mirrors are replaced by diffraction gratings. The SHS contains no moving parts and the gratings are fixed at equal distances from the beam splitter. The main advantage is high throughput, about 200 times higher than that of dispersive spectrometers used in LIBS. This makes LIBS-SHS a promising technique for low-light standoff applications. The output signal of the SHS is an interferogram that is Fourier-transformed to retrieve the original plasma spectrum. In this proof-of-principle study, we investigate the potential of LIBS-SHS for material classification and quantitative analysis. Brass standards with broadly varying concentrations of Cu and Zn were tested. Classification via principal component analysis (PCA) shows distinct groupings of materials according to their origin. The quantification via partial least squares regression (PLS) shows good precision (relative standard deviation < 10%) and accuracy (within ± 5% of nominal concentrations). It is possible that LIBS-SHS can be developed into a portable, inexpensive, rugged instrument for field applications.

  5. Measurement of Irradiated Pyroprocessing Samples via Laser Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Phongikaroon, Supathorn [Virginia Commonwealth Univ., Richmond, VA (United States)

    2016-10-31

    The primary objective of this research is to develop an applied technology and provide an assessment to remotely measure and analyze the real time or near real time concentrations of used nuclear fuel (UNF) dissolute in electrorefiners. Here, Laser-Induced Breakdown Spectroscopy (LIBS), in UNF pyroprocessing facilities will be investigated. LIBS is an elemental analysis method, which is based on the emission from plasma generated by focusing a laser beam into the medium. This technology has been reported to be applicable in the media of solids, liquids (includes molten metals), and gases for detecting elements of special nuclear materials. The advantages of applying the technology for pyroprocessing facilities are: (i) Rapid real-time elemental analysis|one measurement/laser pulse, or average spectra from multiple laser pulses for greater accuracy in < 2 minutes; (ii) Direct detection of elements and impurities in the system with low detection limits|element specific, ranging from 2-1000 ppm for most elements; and (iii) Near non-destructive elemental analysis method (about 1 g material). One important challenge to overcome is achieving high-resolution spectral analysis to quantitatively analyze all important fission products and actinides. Another important challenge is related to accessibility of molten salt, which is heated in a heavily insulated, remotely operated furnace in a high radiation environment with an argon atmosphere.

  6. Laser-induced emission spectrum of UF5

    Science.gov (United States)

    Rice, W. W.; Wampler, F. B.; Oldenborg, R. C.; Lewis, W. B.; Tiee, J. J.; Pack, R. T.

    Results of studies of the laser-induced emission from UF6 irradiated with a KrF laser at 248.4 nm are reported, noting the detection of the electronically excited 3Gamma6 state. The experimental apparatus is described, including operation of the KrF laser at 3-7 Hz repetition rates within the energy range 50-60 mJ output. Emissions were monitored with photomultiplier tubes outside the beam and processed signals were time-resolved or boxcar averaged. Scans were performed with a resolution of 0.87 nm from 200-400 nm and 0.83 nm from 400-900 nm and an example is provided for the average fluence of 0.51 J/sq cm using a gas mixture of 0.19 torr UF6 and 28.45 torr Ar. A single electronic level of 14,647/cm was found for the 17 vibronic levels measured in the near-IR emission. The measured wavelengths are provided, and the existence of 21 unmeasured levels is mentioned.

  7. Laser-induced forward transfer of low viscosity inks

    Science.gov (United States)

    Sopeña, P.; Fernández-Pradas, J. M.; Serra, P.

    2017-10-01

    Laser-induced forward transfer (LIFT) is a laser-based printing technique which has been revealed as an interesting alternative to inkjet printing for the deposition of inks in direct writing applications. The principle of operation of the technique relies on the focusing of a laser beam on a thin film of the ink and the release of a tiny fraction of material through the action of a laser pulse, being usually assumed that such pulse should be very short, of the order of ns and below. However, with the aim of reducing production costs it would be desirable to operate with longer pulses (hundreds of ns and above), so that less expensive lasers could be employed. In this work we prove that it is feasible to carry out the LIFT of liquids with relatively long laser pulses (a few hundreds of ns). To that aim we have investigated the influence of laser fluence on the printed droplets and identified an evolution of their morphology with that parameter somewhat different from the one characteristic of the LIFT of liquids with much shorter pulses. A further time-resolved imaging study has revealed the onset of up to three different transfer mechanisms which correlate well with the deposition outcomes.

  8. Laser-induced forward transfer: Propelling liquids with light

    Science.gov (United States)

    Fernández-Pradas, J. M.; Florian, C.; Caballero-Lucas, F.; Sopeña, P.; Morenza, J. L.; Serra, P.

    2017-10-01

    Laser-induced forward transfer (LIFT) constitutes an interesting alternative to conventional printing techniques in microfabrication applications. Originally developed to print inorganic materials from solid films, it was later proved that LIFT was feasible for printing liquids as well, which substantially broadened the range of printable materials. Any material which can be suspended or dissolved in an ink can be in principle printed through LIFT. The principle of operation of LIFT relies on the localized absorption of a focused laser pulse in a thin film of the ink containing the material to print (donor). This results in the generation of a cavitation bubble which expansion displaces a fraction of the liquid around it, leading to the formation of a jet which propagates away the donor and towards the receiving substrate, placed at a short distance from the liquid free surface. The contact of the jet with this receiving substrate results in the deposition of a sessile droplet. Thus, each droplet results from a single laser pulse, and the generation of micropatterns is achieved through the printing of successive droplets. A similar ejection and deposition process is produced by generating a cavitation bubble below the surface of a liquid contained in a reservoir in the film-free laser printing configuration. In this work we review our main achievements on the laser printing of inks, paying special attention to the analysis of the liquid transfer dynamics and its correlation with the printing outcomes.

  9. Hyperspectral laser-induced autofluorescence imaging of dental caries

    Science.gov (United States)

    Bürmen, Miran; Fidler, Aleš; Pernuš, Franjo; Likar, Boštjan

    2012-01-01

    Dental caries is a disease characterized by demineralization of enamel crystals leading to the penetration of bacteria into the dentine and pulp. Early detection of enamel demineralization resulting in increased enamel porosity, commonly known as white spots, is a difficult diagnostic task. Laser induced autofluorescence was shown to be a useful method for early detection of demineralization. The existing studies involved either a single point spectroscopic measurements or imaging at a single spectral band. In the case of spectroscopic measurements, very little or no spatial information is acquired and the measured autofluorescence signal strongly depends on the position and orientation of the probe. On the other hand, single-band spectral imaging can be substantially affected by local spectral artefacts. Such effects can significantly interfere with automated methods for detection of early caries lesions. In contrast, hyperspectral imaging effectively combines the spatial information of imaging methods with the spectral information of spectroscopic methods providing excellent basis for development of robust and reliable algorithms for automated classification and analysis of hard dental tissues. In this paper, we employ 405 nm laser excitation of natural caries lesions. The fluorescence signal is acquired by a state-of-the-art hyperspectral imaging system consisting of a high-resolution acousto-optic tunable filter (AOTF) and a highly sensitive Scientific CMOS camera in the spectral range from 550 nm to 800 nm. The results are compared to the contrast obtained by near-infrared hyperspectral imaging technique employed in the existing studies on early detection of dental caries.

  10. Laser-induced transfer of gel microdroplets for cell printing

    Science.gov (United States)

    Yusupov, V. I.; Zhigar’kov, V. S.; Churbanova, E. S.; Chutko, E. A.; Evlashin, S. A.; Gorlenko, M. V.; Cheptsov, V. S.; Minaev, N. V.; Bagratashvili, V. N.

    2017-12-01

    We study thermal and transport processes involved in the transfer of gel microdroplets under the conditions of laser cell microprinting. The specific features of the interaction of pulsed laser radiation ( λ = 1.064 µm, pulse duration 4 – 200 ns, energy 2 µJ – 1 mJ) with the absorbing gold film deposited on the glass donor substrate are determined. The investigation of the dynamics of transport processes by means of fast optical video recording and optoacoustic methods makes it possible to determine the characteristics of the produced gel jets as functions of the laser operation regimes. The hydrodynamic process of interaction between the laser radiation and the gold coating with the hydrogel layer on it is considered and the temperature in the region of the laser pulse action is estimated. It is shown that in the mechanism of laser-induced transfer a significant role is played by the processes of explosive boiling of water (in gel) and gold. The amount of gold nanoparticles arriving at the acceptor plate in the process of the laser transfer is determined. For the laser pulse duration 8 ns and small energies (less than 10 µJ), the fraction of gold nanoparticles in the gel microdroplets is negligibly small, and their quantity linearly grows with increasing pulse energy. The performed studies offer a base for optimising the processes of laser transfer of gel microdroplets in the rapidly developing technologies of cell microprinting.

  11. Laser-Induced Photic Injury Phenocopies Macular Dystrophy.

    Science.gov (United States)

    Zhang, Lijuan; Zheng, Andrew; Nie, Hongping; Bhavsar, Kavita V; Xu, Yu; Sliney, David H; Trokel, Stephen L; Tsang, Stephen H

    2016-01-01

    To describe the phenotypes associated with laser-induced retinal damage in children. Five patients with maculopathy and reduced visual acuity associated with laser pointer use were evaluated. Best-corrected visual acuity, retinal structure, and function were monitored with color fundus, infrared (IR), and red-free images, fundus autofluorescence (AF), spectral domain-optical coherence tomography (SD-OCT), and full-field electroretinography (ERG). All five laser pointer injury patients had retinal lesions resembling a macular dystrophy (one bilateral and four unilateral). These lesions were irregular in shape but all had a characteristic dendritic appearance with linear streaks radiating from the lesion. Photoreceptor damage was present in all patients, but serial OCT monitoring showed that subsequent photoreceptor recovery occurred over time in the eyes of at least four patients. One patient also had bilateral pigment epithelial detachments (PED). Both hyper- and hypoautofluorecence were observed in the laser damage area. In general, OCT and IR images are quite useful to diagnose laser damage, but AF is not as sensitive. Laser pointer damage in children can occasionally be misdiagnosed as a macular dystrophy disease, but the distinctive lesions and OCT features are helpful for differentiating laser damage from other conditions.

  12. Update of laser-induced thermotherapy for liver tumors.

    Science.gov (United States)

    Usatoff, V; Habib, N A

    2001-01-01

    Surgical resection generally offers the only chance of long-term survival for patients with primary or secondary liver tumors. Difficulties relating to the stage of the tumor, the extent of underlying liver cirrhosis and the general condition of the patient make this technique unsuitable for the majority of patients. Many nonresectional methods of in-situ tumor ablation have been recently described. These include alcohol injection, cryotherapy, radiofrequency and intraoperative radiotherapy. Recently more interest has been directed to the use of laser as a source of ablative energy. Laser-induced interstitial thermotherapy is an experimental technique used to destroy tumors within the liver. Initially this was in the form of bare-tipped photocoagulation but the development of a diffuser tip has enabled the formation of larger diameter lesions using heat to produce an area of coagulative necrosis. Less heat is lost if hepatic vascular inflow is occluded during the procedure and consequently a larger area of tumor necrosis is produced. The prospect of a simpler, more efficient system of tumor ablation is attractive so we undertook a review of the current issues surrounding this emerging treatment.

  13. Laser Induced Fluorescence for Singly Ionized Atomic Iodine

    Science.gov (United States)

    Steinberger, Thomas; Scime, Earl

    2017-10-01

    While xenon is the standard propellant for a wide range of plasma thrusters, xenon is expensive and xenon propellant systems require heavy compressed gas tanks, pressure regulators, and other bulky hardware. Iodine has similar mass and is much easier to acquire than xenon. Iodines natural state of matter at room temperature is solid and is easily sublimated to gas with a simple heating element. This advantage for iodine is also a significant challenge when developing gas handling systems for iodine. Another challenge for iodine thrusters is a lack of well-defined spectroscopic diagnostics for single ionized iodine, specifically, a lack of a demonstrated laser induced fluorescence (LIF) scheme. We present emission spectroscopy measurements of iodine ion emission from the 6p5P3 - 5d5D4o transition at 695.878 nm and the 6p5P3 - 6s5S2o transition at 516.12 nm as a function of pressure and microwave power for a microwave excited iodine plasma in a sealed quartz cell at a pressure of 1 mTorr. The 5d5D4o state is metastable and was identified by Hargus et al. [48th AIAA Joint Propulsion, 2012] as a strong candidate for an iodine ion LIF scheme. We will also present preliminary LIF measurements using a tunable dye laser operating at 695.878 nm. Special thanks to Dr. William Hargus Jr. and Air Force Research Laboratory at Edwards AFB.

  14. Analysis of bakery products by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Bilge, Gonca; Boyacı, İsmail Hakkı; Eseller, Kemal Efe; Tamer, Uğur; Çakır, Serhat

    2015-08-15

    In this study, we focused on the detection of Na in bakery products by using laser-induced breakdown spectroscopy (LIBS) as a quick and simple method. LIBS experiments were performed to examine the Na at 589 nm to quantify NaCl. A series of standard bread sample pellets containing various concentrations of NaCl (0.025-3.5%) were used to construct the calibration curves and to determine the detection limits of the measurements. Calibration graphs were drawn to indicate functions of NaCl and Na concentrations, which showed good linearity in the range of 0.025-3.5% NaCl and 0.01-1.4% Na concentrations with correlation coefficients (R(2)) values greater than 0.98 and 0.96. The obtained detection limits for NaCl and Na were 175 and 69 ppm, respectively. Performed experimental studies showed that LIBS is a convenient method for commercial bakery products to quantify NaCl concentrations as a rapid and in situ technique. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Ultraviolet Laser-induced ignition of RDX single crystal.

    Science.gov (United States)

    Yan, Zhonghua; Zhang, Chuanchao; Liu, Wei; Li, Jinshan; Huang, Ming; Wang, Xuming; Zhou, Guorui; Tan, Bisheng; Yang, Zongwei; Li, Zhijie; Li, Li; Yan, Hongwei; Yuan, Xiaodong; Zu, Xiaotao

    2016-02-05

    The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. As laser fluence increases, the area of the whole crack region increases all the way, while both the area and depth of the core region increase firstly, and then stay stable over the laser fluence of 12 J/cm(2). The experimental details indicate the dynamics during laser ignition process. Plasma fireball of high temperature and pressure occurs firstly, followed by the micro-explosions on the (210) surface, and finally shock waves propagate through the materials to further strip materials outside and yield in-depth cracks in larger surrounding region. The plasma fireball evolves from isotropic to anisotropic under higher laser fluence resulting in the damage expansion only in lateral direction while maintaining the fixed depth. The primary insights into the interaction dynamics between laser and energetic materials can help developing the superior laser ignition technique.

  16. Determination of flame temperature using laser induced fluorescence (LIF)

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Lina Augusta Martins Ramos da [Instituto Tecnologico de Aeronautica (ITA/DCTA), Sao Jose dos Campos, SP (Brazil); Barreta, Gilberto; Carinhana Junior, Dermeval; Toledo, Antonio Osny de [Instituto de Estudos Avancados (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil)

    2011-07-01

    Full text: Laser Induced Fluorescence, LIF, is one of the most used techniques in combustion diagnostics. The excitation method is based on the spontaneous spectrum from atoms or molecules that were excited by laser radiation. In general, intermediated combustion species, as OH and CH radicals, are used as temperature probes. Usually, several rotational levels are used by tuning the laser afterwards across the corresponding absorption transitions. The emission spectrum is detected in a convenient spectral range. The accuracy of measurements depends on the laser linewidth, the delay between the laser excitation and spectra detection and, mainly, the spectral interval of laser excitation. In this work, OH LIF spectra from stoichiometric LPG (Liquefied Petroleum Gas) flames were obtained using a tuned laser with a spectral range set from 282 nm up to 283 nm. This corresponds to the rotation levels of the 0-1 vibration band of OH radical. The laser energy was ca. 0.2 mJ. The emission spectrum was collected in the spectral range of the 305-310 nm, which corresponds to the region of the 0-0 band. The temperature was determined by the Boltzmann method. This is based on the measurement of the relative peak intensities of the emission spectrum. A plot of natural logarithm of line intensities versus energy level returns a straight line, whose slope is the inverse of the rotational temperature. The flame temperature was ca. 2300 K. This value is consistent with previous results obtained in our laboratory. (author)

  17. Airborne laser induced fluorescence imaging. Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-06-01

    Laser-Induced Fluorescence (LIF) was demonstration as part of the Fernald Environmental Management Project (FEMP) Plant 1 Large Scale Demonstration and Deployment Project (LSDDP) sponsored by the US Department of Energy (DOE) Office of Science and Technology, Deactivation and Decommissioning Focus Area located at the Federal Energy Technology Center (FETC) in Morgantown, West Virginia. The demonstration took place on November 19, 1996. In order to allow the contaminated buildings undergoing deactivation and decommissioning (D and D) to be opened to the atmosphere, radiological surveys of floors, walls and ceilings must take place. After successful completion of the radiological clearance survey, demolition of the building can continue. Currently, this process is performed by collecting and analyzing swipe samples for radiological analysis. Two methods are used to analyze the swipe samples: hand-held frisker and laboratory analysis. For the purpose of this demonstration, the least expensive method, swipe samples analyzed by hand-held frisker, is the baseline technology. The objective of the technology demonstration was to determine if the baseline technology could be replaced using LIF.

  18. Focal choroidal excavation: Clinical findings and complications.

    Science.gov (United States)

    Castro Navarro, V; Montero Hernández, J; Navarro Palop, C; Palomares Fort, P; Cervera Taulet, E

    2016-01-01

    To describe the clinical findings and its complications in 2 patients with focal choroidal excavation (FCE). A retrospective case-series including 4 eyes of 2 patients with FCE that underwent a comprehensive ophthalmological examination including slit-lamp examination, colour fundus photography, spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography (FA), and indocyanine green angiography. In the 2 patients, both the anterior and posterior segment evaluations were mostly normal despite the of presence yellowish spots in the macular area of the right eye of patient 1, and of a small yellowish elevated lesion with serous macular detachment in the macular area of the left eye in patient 2. At diagnosis, SD-OCT revealed a conforming FCE in patient 1, and in patient 2, an FCE with perilesional subretinal fluid and a neuroepithelium detachment, suspicious of FCE complicated with central serous retinopathy (CSCR). At one year of follow-up, patient 1 developed choroidal neovascularisation (CNV) over the focal choroidal excavation. FA and indocyanine green angiography examinations revealed areas with hypofluorescence in earlier frames, and a diffuse leakage in late frames. After ranibizumab injections, the SD-OCT of patient 1 revealed no active exudation, while patient 2 showed partial resolution of subretinal fluid. FCE is a newly described entity of unclear aetiology. It is characterised by a choroidal excavation in eyes, with absence of posterior staphyloma, scleral ectasia, trauma, or retinal disease. Although most lesions remain stable, there could be an association with CRSC or CNV. Copyright © 2015 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  19. Focal Choroidal Excavation in Retinal Dystrophies.

    Science.gov (United States)

    Braimah, Imoro Zeba; Rapole, Shruthi; Dumpala, Sunila; Chhablani, Jay

    2016-08-17

    To investigate the presence of focal choroidal excavation (FCE) in patients with retinitis pigmentosa (RP), Stargardt's disease (STGD), and Best disease in the Indian population. This retrospective consecutive case series included 309 eyes of 157 patients with RP (183 eyes), STGD (93 eyes), and Best disease (33 eyes) with good-quality, enhanced-depth spectral domain optical coherence tomography scans. Comprehensive ophthalmic examination data were collected. Characteristics of FCE, including location of FCE, type (conforming and non-conforming), maximal width, and depth, were noted. FCE was found in 2 out of 33 (6%) eyes with Best disease and no FCE was found in eyes with RP or STGD. The location of the FCE was extrafoveal in both cases. The first case had non-conforming FCE while the second case had the conforming type and the FCE occurred in association with choroidal neovascularization in the second case. The first case maintained good visual acuity of 20/20 over the entire period of follow-up (14 months), while the second case had a visual acuity of 20/200 at the last follow-up (three years) due to scarred choroidal neovascular membranes. The FCE showed no change in both eyes over the entire duration of follow-up. Focal choroidal excavation was found in 6% of eyes with Best disease, which remained stable throughout follow up. Eyes with RP and STGD did not have any FCE. Further studies are required to determine the role of vitelliform material in FCE development in Best disease.

  20. Single intravitreal ranibizumab for myopic choroidal neovascularization

    OpenAIRE

    Nor-Masniwati, Saidin; Shatriah, Ismail; Zunaina, Embong

    2011-01-01

    Saidin Nor-Masniwati, Ismail Shatriah, Embong ZunainaDepartment of Ophthalmology, Universiti Sains Malaysia, Kelantan, MalaysiaAbstract: We report a case of myopic choroidal neovascularization that showed improvement after a single injection of ranibizumab. A 45-year-old Chinese man with high myopia presented with sudden onset painless central scotoma of his right eye of 2 weeks’ duration. There was no history of trauma. His right eye vision on presentation was 6/30 which showed no ...

  1. Another Form of Focal Choroidal Excavation Based on Multimodality Imaging.

    Science.gov (United States)

    Wang, Shiyuan; Zhao, Peiquan

    2016-10-01

    To describe a peculiar choroidal entity using multimodality imaging and to further understand the relationship between focal choroidal excavation and central serous chorioretinopathy. A peculiar entity was detected in both eyes of a 20-year-old male patient who was followed for more than 4 years; one perifoveal focal choroidal excavation and two extrafoveal focal choroidal excavations were noted in each eye. The bilateral perifoveal focal choroidal excavations exhibited progressive development with repeated interconversion between the nonconforming and conforming types. Dilated choroid blood vessels were detected by en face spectral-domain optical coherence tomography (SD-OCT). Although the ellipsoid zone and retinal pigment epithelium layer defect also involved the fovea, a visual acuity of 20/20 was maintained in both eyes, with neither metamorphopsia by Amsler grid nor abnormalities noted by multifocal electroretinogram. However, pigment epithelium detachment finally appeared in the right eye. The microperimetry test revealed reduced threshold sensitivity corresponding to the lesions, and near-infrared autofluorescence revealed increased hyperfluorescence at the latest visit. Idiopathic focal choroidal excavation may convert to the structure of central serous chorioretinopathy alike, which likely indicates another rare condition of focal choroidal excavation or central serous chorioretinopathy. Wide- and deep-scanning modes should be routinely applied in OCT imaging to detect choroidal disorders.

  2. Long-Term Follow-Up of Intravitreal Ranibizumab for the Treatment of Choroidal Neovascularization due to Choroidal Osteoma

    Directory of Open Access Journals (Sweden)

    Zenith H.Y. Wu

    2012-06-01

    Full Text Available Choroidal osteoma is an uncommon benign osseous intraocular tumor that typically affects young adult women. Choroidal neovascularization (CNV is one of the complications that can develop in eyes with choroidal osteoma. We present a case of CNV secondary to choroidal osteoma treated with intravitreal ranibizumab. A 57-year-old lady presented with painless loss of vision with a right-eye visual acuity of 20/800. Fundus examination showed a well-demarcated yellowish peripapillary choroidal osteoma with associated retinal and subretinal hemorrhage due to CNV. Three intravitreal ranibizumab injections at monthly intervals were given and her visual acuity improved to 20/30 following treatment. After 1.2 years of follow-up, the right eye visual acuity was maintained at 20/30 with no evidence of CNV recurrence. Our findings suggest that intravitreal ranibizumab may be an effective therapeutic option for treating CNV secondary to choroidal osteoma.

  3. Idiopathic polypoidal choroidal vasculopathy masquerading as choroidal tumors: one year follow-up of a peripheral lesion

    Directory of Open Access Journals (Sweden)

    Rony Carlos Preti

    2015-06-01

    Full Text Available ABSTRACT This case report describes peripheral idiopathic polypoidal choroidal vasculopathy (IPCV with a collection of small aneurysmal dilations that masqueraded as choroidal tumors in an elderly patient. A 68-year-old African American woman was referred to us with a suspected diagnosis of asymptomatic vascular choroidal tumor and choroidal capillary hemangioma, affecting the temporal peripheral fundus. Upon examination, optical coherence tomography (OCT revealed two large hemorrhagic pigment epithelium detachments (PED, and indocyanine green angiography (ICG confirmed the diagnosis of IPCV. One year later, there was reduction in the hemorrhagic pigment epithelium detachments and the lesion took on a different appearance, resembling a choroidal osteoma. No treatment was necessary despite the presence of multiple polyps. IPCV is a rare condition that can resemble other choroidal diseases depending on the stage of presentation. OCT is the best tool to determine the characteristics of the lesions, and indocyanine green angiography should be used to confirm the diagnosis. Not all cases require treatment.

  4. Optical Coherence Tomography Angiography Study of Choroidal Neovascularization Associated With Focal Choroidal Excavation.

    Science.gov (United States)

    Chawla, Rohan; Mittal, Kanhaiya; Vohra, Rajpal

    2016-10-01

    The authors report the use of optical coherence tomography angiography (OCTA) (DRI OCT Triton; Topcon, Tokyo, Japan) to localize, characterize, and confirm the presence of a choroidal neovascular membrane in a patient of focal choroidal excavation (FCE) with recent-onset metamorphopsia and visual blurring. En face OCTA images just above the level of the retinal pigment epithelium-Bruch's membrane complex typically showed the presence of a glomerulus-like neovascular network with an adjacent dark area suggestive of a Type 2 choroidal neovascularization (CNV). OCTA was found to be a very useful, noninvasive, and quick imaging modality to detect secondary CNV formation in a case of FCE. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:969-971.]. Copyright 2016, SLACK Incorporated.

  5. MSL CHEMCAM LASER INDUCED BREAKDOWN SPECTROMETER EDR V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MSL ChemCam LIBS EDR data set consists of all uncalibrated data collected by the ChemCam Laser Induced Breakdown Spectrometer on the Mars Science Laboratory...

  6. Laser-induced ultrafast demagnetization in the presence of a nanoscale magnetic domain network

    National Research Council Canada - National Science Library

    Vodungbo, Boris; Gautier, Julien; Lambert, Guillaume; Sardinha, Anna Barszczak; Lozano, Magali; Sebban, Stéphane; Ducousso, Mathieu; Boutu, Willem; Li, Kaigong; Tudu, Bharati; Tortarolo, Marina; Hawaldar, Ranjit; Delaunay, Renaud; López-Flores, Victor; Arabski, Jacek; Boeglin, Christine; Merdji, Hamed; Zeitoun, Philippe; Lüning, Jan

    2012-01-01

    ... on a femtosecond timescale. Here we study laser-induced ultrafast demagnetization in [Co/Pd](30) multilayer films, which, for the first time, achieves a spatial resolution better than 100 nm by using femtosecond soft X-ray pulses...

  7. Laser-Induced Emissions Sensor for Soot Mass in Rocket Plumes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A method is proposed to measure soot mass concentration non-intrusively from a distance in a rocket engine exhaust stream during ground tests using laser-induced...

  8. Laser-induced multi-point ignition for enabling high-performance engines

    KAUST Repository

    Chung, Suk-Ho

    2015-01-01

    Various multi-point laser-induced ignition techniques were reviewed, which adopted conical cavity and prechamber configurations. Up to five-point ignitions have been achieved with significant reduction in combustion duration, demonstrating potential increase in combustion system efficiency.

  9. Laser-induced versus shock wave induced transformation of highly ordered pyrolytic graphite

    OpenAIRE

    Pezeril, T.; Bulou, A.; Veysset, David Georges; Kooi, Steven E.; Nelson, Keith Adam

    2015-01-01

    We demonstrate that in-plane 2D propagation and focusing of a laser-induced shock wave result in enhanced nano-crystallization of highly ordered pyrolytic graphite. Throughout the 2D shock focusing technique, which enables to clearly distinguish between the laser-induced and the shock-induced transformation/transition, our findings establish the role of the shock wave during the transformation/transition process. This configuration could open the way to an alternative path for laser shock fab...

  10. Combination therapy of low-fluence photodynamic therapy and intravitreal ranibizumab for choroidal neovascular membrane in choroidal osteoma

    Directory of Open Access Journals (Sweden)

    Rodney J Morris

    2011-01-01

    Full Text Available Choroidal osteoma is an unusual form of intraocular calcification seen in otherwise healthy eyes. It is a benign idiopathic osseous tumor of the choroid, typically seen in young females. Choroidal neovascular membrane (CNVM is a complication seen in one-third of these patients and carries a poor visual outcome. We report a case of a 25-year-old hyperthyroid female with choroidal osteoma and subfoveal CNVM in her left eye which was successfully treated using low-fluence photodynamic therapy (PDT with verteporfin followed by a single injection of intravitreal ranibizumab.

  11. Subsurface defects of fused silica optics and laser induced damage at 351 nm.

    Science.gov (United States)

    Hongjie, Liu; Jin, Huang; Fengrui, Wang; Xinda, Zhou; Xin, Ye; Xiaoyan, Zhou; Laixi, Sun; Xiaodong, Jiang; Zhan, Sui; Wanguo, Zheng

    2013-05-20

    Many kinds of subsurface defects are always present together in the subsurface of fused silica optics. It is imperfect that only one kind of defects is isolated to investigate its impact on laser damage. Therefore it is necessary to investigate the impact of subsurface defects on laser induced damage of fused silica optics with a comprehensive vision. In this work, we choose the fused silica samples manufactured by different vendors to characterize subsurface defects and measure laser induced damage. Contamination defects, subsurface damage (SSD), optical-thermal absorption and hardness of fused silica surface are characterized with time-of-flight secondary ion mass spectrometry (TOF-SIMS), fluorescence microscopy, photo-thermal common-path interferometer and fully automatic micro-hardness tester respectively. Laser induced damage threshold and damage density are measured by 351 nm nanosecond pulse laser. The correlations existing between defects and laser induced damage are analyzed. The results show that Cerium element and SSD both have a good correlation with laser-induced damage thresholds and damage density. Research results evaluate process technology of fused silica optics in China at present. Furthermore, the results can provide technique support for improving laser induced damage performance of fused silica.

  12. Laser induced x-ray `RADAR' particle physics model

    Science.gov (United States)

    Lockley, D.; Deas, R.; Moss, R.; Wilson, L. A.; Rusby, D.; Neely, D.

    2016-05-01

    The technique of high-power laser-induced plasma acceleration can be used to generate a variety of diverse effects including the emission of X-rays, electrons, neutrons, protons and radio-frequency radiation. A compact variable source of this nature could support a wide range of potential applications including single-sided through-barrier imaging, cargo and vehicle screening, infrastructure inspection, oncology and structural failure analysis. This paper presents a verified particle physics simulation which replicates recent results from experiments conducted at the Central Laser Facility at Rutherford Appleton Laboratory (RAL), Didcot, UK. The RAL experiment demonstrated the generation of backscattered X-rays from test objects via the bremsstrahlung of an incident electron beam, the electron beam itself being produced by Laser Wakefield Acceleration. A key initial objective of the computer simulation was to inform the experimental planning phase on the predicted magnitude of the backscattered X-rays likely from the test objects. This objective was achieved and the computer simulation was used to show the viability of the proposed concept (Laser-induced X-ray `RADAR'). At the more advanced stages of the experimental planning phase, the simulation was used to gain critical knowledge of where it would be technically feasible to locate key diagnostic equipment within the experiment. The experiment successfully demonstrated the concept of X-ray `RADAR' imaging, achieved by using the accurate timing information of the backscattered X-rays relative to the ultra-short laser pulse used to generate the electron beam. By using fast response X-ray detectors it was possible to derive range information for the test objects being scanned. An X-ray radar `image' (equivalent to a RADAR B-scan slice) was produced by combining individual X-ray temporal profiles collected at different points along a horizontal distance line scan. The same image formation process was used to generate

  13. Application of Laser Induced Breakdown Spectroscopy under Polar Conditions

    Science.gov (United States)

    Clausen, J. L.; Hark, R.; Bol'shakov, A.; Plumer, J.

    2015-12-01

    Over the past decade our research team has evaluated the use of commercial-off-the-shelf laser-induced breakdown spectroscopy (LIBS) for chemical analysis of snow and ice samples under polar conditions. One avenue of research explored LIBS suitability as a detector of paleo-climate proxy indicators (Ca, K, Mg, and Na) in ice as it relates to atmospheric circulation. LIBS results revealed detection of peaks for C and N, consistent with the presence of organic material, as well as major ions (Ca, K, Mg, and Na) and trace metals (Al, Cu, Fe, Mn, Ti). The detection of Ca, K, Mg, and Na confirmed that LIBS has sufficient sensitivity to be used as a tool for characterization of paleo-climate proxy indicators in ice-core samples. Techniques were developed for direct analysis of ice as well as indirect measurements of ice via melting and filtering. Pitfalls and issues of direct ice analysis using several cooling techniques to maintain ice integrity will be discussed. In addition, a new technique, laser ablation molecular isotopic spectroscopy (LAMIS) was applied to detection of hydrogen and oxygen isotopes in ice as isotopic analysis of ice is the main tool in paleoclimatology and glaciology studies. Our results demonstrated that spectra of hydroxyl isotopologues 16OH, 18OH, and 16OD can be recorded with a compact spectrograph to determine hydrogen and oxygen isotopes simultaneously. Quantitative isotopic calibration for ice analysis can be accomplished using multivariate chemometric regression as previously realized for water vapor. Analysis with LIBS and LAMIS required no special sample preparation and was about ten times faster than analysis using ICP-MS. Combination of the two techniques in one portable instrument for in-field analysis appears possible and would eliminate the logistical and cost issues associated with ice core management.

  14. Characterization Of High Explosives Detonations Via Laser-Induced Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Aleman, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    One objective of the Department of Energy’s National Security Administration is to develop technologies that can help the United States government to detect foreign nuclear weapons development activities. The realm of high explosive (HE) experiments is one of the key areas to assess the nuclear ambitions of a country. SRNL has participated in the collection of particulates from HE experiments and characterized the material with the purpose to correlate particulate matter with HE. Since these field campaigns are expensive, on-demand simulated laboratory-scale explosion experiments are needed to further our knowledge of the chemistry and particle formation in the process. Our goal is to develop an experimental test bed in the laboratory to test measurement concepts and correlate particle formation processes with the observables from the detonation fireball. The final objective is to use this knowledge to tailor our experimental setups in future field campaigns. The test bed uses pulsed laser-induced plasmas to simulate micro-explosions, with the intent to study the temporal behavior of the fireball observed in field tests. During FY15, a plan was prepared and executed which assembled two laser ablation systems, procured materials for study, and tested a Step-Scan Fourier Transform Infrared Spectrometer (SS-FTIR). Designs for a shadowgraph system for shock wave analysis, design for a micro-particulate collector from ablated pulse were accomplished. A novel spectroscopic system was conceived and a prototype system built for acquisition of spectral/temporal characterization of a high speed event such as from a high explosive detonation. Experiments and analyses will continue into FY16.

  15. Lanthanide-based laser-induced phosphorescence for spray diagnostics

    Science.gov (United States)

    van der Voort, D. D.; Maes, N. C. J.; Lamberts, T.; Sweep, A. M.; van de Water, W.; Kunnen, R. P. J.; Clercx, H. J. H.; van Heijst, G. J. F.; Dam, N. J.

    2016-03-01

    Laser-induced phosphorescence (LIP) is a relatively recent and versatile development for studying flow dynamics. This work investigates certain lanthanide-based molecular complexes for their use in LIP for high-speed sprays. Lanthanide complexes in solutions have been shown to possess long phosphorescence lifetimes (˜1-2 ms) and to emit light in the visible wavelength range. In particular, europium and terbium complexes are investigated using fluorescence/phosphorescence spectrometry, showing that europium-thenoyltrifluoracetone-trioctylphosphineoxide (Eu-TTA-TOPO) can be easily and efficiently excited using a standard frequency-tripled Nd:YAG laser. The emitted spectrum, with maximum intensity at a wavelength of 614 nm, is shown not to vary strongly with temperature (293-383 K). The decay constant of the phosphorescence, while independent of ambient pressure, decreases by approximately 12 μs/K between 323 and 373 K, with the base level of the decay constant dependent on the used solvent. The complex does not luminesce in the gas or solid state, meaning only the liquid phase is visualized, even in an evaporating spray. By using an internally excited spray containing the phosphorescent complex, the effect of vaporization is shown through the decrease in measured intensity over the length of the spray, together with droplet size measurements using interferometric particle imaging. This study shows that LIP, using the Eu-TTA-TOPO complex, can be used with different solvents, including diesel surrogates. Furthermore, it can be easily handled and used in sprays to investigate spray breakup and evaporation.

  16. Lanthanide-based laser-induced phosphorescence for spray diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Voort, D. D. van der, E-mail: d.d.v.d.voort@tue.nl; Water, W. van de; Kunnen, R. P. J.; Clercx, H. J. H.; Heijst, G. J. F. van [Applied Physics Department, Eindhoven University of Technology, 5612 AZ Eindhoven (Netherlands); Maes, N. C. J.; Sweep, A. M.; Dam, N. J. [Mechanical Engineering Department, Eindhoven University of Technology, 5612 AZ Eindhoven (Netherlands); Lamberts, T. [Institute of Theoretical Chemistry, University of Stuttgart, D-70569 Stuttgart (Germany)

    2016-03-15

    Laser-induced phosphorescence (LIP) is a relatively recent and versatile development for studying flow dynamics. This work investigates certain lanthanide-based molecular complexes for their use in LIP for high-speed sprays. Lanthanide complexes in solutions have been shown to possess long phosphorescence lifetimes (∼1-2 ms) and to emit light in the visible wavelength range. In particular, europium and terbium complexes are investigated using fluorescence/phosphorescence spectrometry, showing that europium-thenoyltrifluoracetone-trioctylphosphineoxide (Eu-TTA-TOPO) can be easily and efficiently excited using a standard frequency-tripled Nd:YAG laser. The emitted spectrum, with maximum intensity at a wavelength of 614 nm, is shown not to vary strongly with temperature (293-383 K). The decay constant of the phosphorescence, while independent of ambient pressure, decreases by approximately 12 μs/K between 323 and 373 K, with the base level of the decay constant dependent on the used solvent. The complex does not luminesce in the gas or solid state, meaning only the liquid phase is visualized, even in an evaporating spray. By using an internally excited spray containing the phosphorescent complex, the effect of vaporization is shown through the decrease in measured intensity over the length of the spray, together with droplet size measurements using interferometric particle imaging. This study shows that LIP, using the Eu-TTA-TOPO complex, can be used with different solvents, including diesel surrogates. Furthermore, it can be easily handled and used in sprays to investigate spray breakup and evaporation.

  17. Laser-induced boiling of biological liquids in medical technologies

    Science.gov (United States)

    Chudnovskii, V. M.; Yusupov, V. I.; Dydykin, A. V.; Nevozhai, V. I.; Kisilev, A. Yu.; Zhukov, S. A.; Bagratashvili, V. N.

    2017-05-01

    Using optical and acoustic methods we study thermal and transport processes related to the boiling of biological liquids under the action of continuous-wave laser radiation having moderate power (1 - 10 W) in the near-IR range (0.97 - 1.94 μm). These processes are investigated in the course of a few particular clinical procedures aimed at the modification and removal of pathological tissues (veins, mammary gland cyst, Baker’s cyst) and tissue regeneration (intervertebral discs). In the proposed approach, the modification and destruction of biotissues are due to the fast delivery of heat by two-phase jet flows, formed in the course of liquid boiling, rather than the direct laser heating. This provides the high rate of heat delivery to the pathological biotissue, avoiding its overheating (the temperature higher than 100 °C) and undesired heating of adjacent tissues. Two main regimes of laser-induced boiling near the optical fibre tip were revealed, namely, the heterogeneous jet boiling (arising when the fibre with a blackened tip is used) and the homogeneous boiling (with the radiation absorbed in the liquid volume). Both studied regimes allow one to obtain high specific heat flows, and the domination of one of the boiling regimes is determined by the presence of absorbing coating on the fibre tip, the tissue type, as well as by its shape (e.g., the presence of channels or cavities in the tissue). It is established that the heterogeneous jet boiling at the fibre tip corresponds to the regime of superintensive bubble boiling.

  18. Liquid Jet Formation in Laser-Induced Forward Transfer

    Science.gov (United States)

    Brasz, C. Frederik

    Laser-induced forward transfer (LIFT) is a direct-write technique capable of printing precise patterns of a wide variety of materials. In this process, a laser pulse is focused through a transparent support and absorbed in a thin donor film, propelling material onto an adjacent acceptor substrate. For fluid materials, this transfer occurs through the formation of a narrow liquid jet, which eventually pinches off due to surface tension. This thesis examines in detail the fluid mechanics of the jet formation process occurring in LIFT. The main focus is on a variant of LIFT known as blister-actuated LIFT (BA-LIFT), in which the laser pulse is absorbed in an ink-coated polymer layer, rapidly deforming it locally into a blister to induce liquid jet formation. The early-time response of a fluid layer to a deforming boundary is analyzed with a domain perturbation method and potential-flow simulations, revealing scalings for energy and momentum transfer to the fluid and providing physical insight on how and why a jet forms in BA-LIFT. The remaining chapters explore more complex applications and modifications of LIFT. One is the possibility of high-repetition rate printing and limits on time delay and separation between pulses imposed by a tilting effect found for adjacent jets. Another examines a focusing effect achieved by perturbing the interface with ring-shaped disturbances. The third contains an experimental study of LIFT using a silver paste as the donor material instead of a Newtonian liquid. The transfer mechanism is significantly different, although with repeated pulses at one location, a focusing effect is again observed. All three of these chapters investigate how perturbations to the interface can strongly influence the jet formation process.

  19. Standoff laser-induced thermal emission of explosives

    Science.gov (United States)

    Galán-Freyle, Nataly Y.; Pacheco-Londoño, Leonardo C.; Figueroa-Navedo, Amanda; Hernandez-Rivera, Samuel P.

    2013-05-01

    A laser mediated methodology for remote thermal excitation of analytes followed by standoff IR detection is proposed. The goal of this study was to determine the feasibility of using laser induced thermal emission (LITE) from vibrationally excited explosives residues deposited on surfaces to detect explosives remotely. Telescope based FT-IR spectral measurements were carried out to examine substrates containing trace amounts of threat compounds used in explosive devices. The highly energetic materials (HEM) used were PETN, TATP, RDX, TNT, DNT and ammonium nitrate with concentrations from 5 to 200 μg/cm2. Target substrates of various thicknesses were remotely heated using a high power CO2 laser, and their mid-infrared (MIR) thermally stimulated emission spectra were recorded. The telescope was configured from reflective optical elements in order to minimize emission losses in the MIR frequencies and to provide optimum overall performance. Spectral replicas were acquired at a distance of 4 m with an FT-IR interferometer at 4 cm- 1 resolution and 10 scans. Laser power was varied from 4-36 W at radiation exposure times of 10, 20, 30 and 60 s. CO2 laser powers were adjusted to improve the detection and identification of the HEM samples. The advantages of increasing the thermal emission were easily observed in the results. Signal intensities were proportional to the thickness of the coated surface (a function of the surface concentration), as well as the laser power and laser exposure time. For samples of RDX and PETN, varying the power and time of induction of the laser, the calculated low limit of detections were 2 and 1 μg/cm2, respectively.

  20. Characterisation of estuarine intertidal macroalgae by laser-induced fluorescence

    Science.gov (United States)

    Gameiro, Carla; Utkin, Andrei B.; Cartaxana, Paulo

    2015-12-01

    The article reports the application of laser-induced fluorescence (LIF) for the assessment of macroalgae communities of estuarine intertidal areas. The method was applied for the characterisation of fifteen intertidal macroalgae species of the Tagus estuary, Portugal, and adjacent coastal area. Three bands characterised the LIF spectra of red macroalgae with emission maxima in the ranges 577-583 nm, 621-642 nm and 705-731 nm. Green and brown macroalgae showed one emission maximum in the red region (687-690 nm) and/or one in the far-red region (726-732 nm). Characteristics of LIF emission spectra were determined by differences in the main fluorescing pigments: phycoerythrin, phycocyanin and chlorophyll a (Chl a). In the green and brown macroalgae groups, the relative significance of the two emission maxima seems to be related to the thickness of the photosynthetic layer. In thick macroalgae, like Codium tomentosum or Fucus vesiculosus, the contribution of the far-red emission fluorescence peak was more significant, most probably due to re-absorption of the emitted red Chl a fluorescence within the dense photosynthetic layer. Similarly, an increase in the number of layers of the thin-blade green macroalgae Ulva rigida caused a shift to longer wavelengths of the red emission maximum and the development of a fluorescence peak at the far-red region. Water loss from Ulva's algal tissue also led to a decrease in the red/far-red Chl fluorescence ratio (F685/F735), indicating an increase in the density of chloroplasts in the shrinking macroalgal tissue during low tide exposure.

  1. Characterization of cinematographic films by Laser Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gaspard, S. [Rocasolano Institute of Physical Chemistry, CSIC, Serrano 119, 28006 Madrid (Spain)], E-mail: sgaspard@iqfr.csic.es; Oujja, M.; Rebollar, E. [Rocasolano Institute of Physical Chemistry, CSIC, Serrano 119, 28006 Madrid (Spain); Abrusci, C.; Catalina, F. [Institute of Polymer Science and Technology, CSIC, Juan de la Cierva 3, 28006 Madrid (Spain); Castillejo, M. [Rocasolano Institute of Physical Chemistry, CSIC, Serrano 119, 28006 Madrid (Spain)

    2007-12-15

    The emulsion-coated transparent plastic-base film has been the main carrier for production and preservation of motion picture contents since the 19th century. The knowledge of the composition of black and white silver gelatine cinematographic films is of great importance for the characterization of the photographic process and for identifying the optimum conditions for conservation. A cinematographic film is a multi-component system that consists of a layer of photographic emulsion overcoating a polymeric support (plasticized cellulose triacetate) and a protective transparent cross-linked gelatine layer coating the emulsion. In the present work, Laser Induced Breakdown Spectroscopy (LIBS) is used to characterize the composition of the materials of cinematographic films. LIB spectra of film samples and of different individual film components, polymeric support and reference gelatines, were acquired in vacuum by excitation at 266 nm (Q-switched Nd:YAG laser, 6 ns, 10 Hz). In the cinematographic film, silver lines from the light-sensitive silver halide salts of the photographic emulsion are accompanied by iron, lead, chrome and phosphorus lines. Iron and lead are constituents of film developers, chrome is included in the composition of the hardening agents and phosphorus has its origin in the plasticizer used in the polymeric support. By applying successive pulses on the same spot of the film sample, it was possible to observe through stratigraphic analysis the different layers composition. Additionally, the results obtained reveal the analytical capacity of LIBS for the study and classification of the different gelatine types and qualities used for the protecting layer and the photographic emulsion.

  2. TNF-α mediates choroidal neovascularization by upregulating VEGF expression in RPE through ROS-dependent β-catenin activation.

    Science.gov (United States)

    Wang, Haibo; Han, Xiaokun; Wittchen, Erika S; Hartnett, M Elizabeth

    2016-01-01

    Inflammation, oxidative stress, and angiogenesis have been proposed to interact in age-related macular degeneration. It has been postulated that external stimuli that cause oxidative stress can increase production of vascular endothelial growth factor (VEGF) in retinal pigment epithelial (RPE) cells. In this study, we tested the hypothesis that the inflammatory cytokine, tumor necrosis factor alpha (TNF-α), contributed to choroidal neovascularization (CNV) by upregulating VEGF in RPE through intracellular reactive oxygen species (ROS)-dependent signaling and sought to understand the mechanisms involved. In a murine laser-induced CNV model, 7 days after laser treatment and intravitreal neutralizing mouse TNF-α antibody or isotype immunoglobulin G (IgG) control, the following measurements were made: 1) TNF-α protein and VEGF protein in RPE/choroids with western blot, 2) CNV volume in RPE/choroidal flatmounts, and 3) semiquantification of oxidized phospholipids stained with E06 antibody within CNV with immunohistochemistry (IHC). In cultured human RPE cells treated with TNF-α or PBS control, 1) ROS generation was measured using the 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescence assay, and 2) NOX4 protein and VEGF protein or mRNA were measured with western blot or quantitative real-time PCR in cells pretreated with apocynin or nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) inhibitor, VAS 2870, or transfected with p22phox siRNA, and each was compared to its appropriate control. Western blots of phosphorylated p65 (p-p65), total p65 and β-actin, and quantitative real-time PCR of VEGF mRNA were measured in human RPE cells treated with TNF-α and pretreatment with the nuclear factor kappa B inhibitor, Bay 11-7082 or control. Western blots of β-catenin, VEGF, and p22phox and coimmunoprecipitation of β-catenin and T-cell transcriptional factor were performed in human RPE cells treated with TNF-α following pretreatment with

  3. Clinical features of choroidal metastases from carcinoid tumour.

    Science.gov (United States)

    She, Huaning; Zheng, Yuping; Wang, Xiaohua; Quan, Yanlong; Sun, Naixue

    2004-03-01

    To report ophthalmologic and angiographic features of choroidal metastases from carcinoid tumor and analyze their common clinical manifestation. Ophthalmologic examinations and fundus fluorescein angiography (FFA) were performed in 30 patients suffered from carcinoid tumor, and four patients diagnosed of breast cancer (2 cases), lung cancer (1 case) and maxillary sinus cancer (1 case) were confirmed with choroidal metastases. Choroidal metastases were found as the initial manifestations of the malignant tumors on 2 patients whose initial and chief complaints were decreasing vision, their fundus lesions were mainly presented in the posterior pole and FFA showed high density of fluorescence of the lesions. This study indicated choroidal metastasis might be the first sign of metastases for patients with cancer. For patients with unknown metastasic cancers, examinations of the choroids may be useful for diagnosis and prognosis.

  4. Torpedo maculopathy: A primary choroidal capillary abnormality?

    Directory of Open Access Journals (Sweden)

    Rohan Chawla

    2018-01-01

    Full Text Available A 26-year-old healthy male patient's fundus revealed findings consistent with torpedo maculopathy. Swept-source optical coherence tomography (OCT showed a dome-shaped elevation of the retina at the level of ellipsoid zone. On OCT angiography segmented at the level of the choriocapillaris, a cluster of convoluted fine vessels was seen, and further, deeper scans of the larger choroidal vessels showed a slower flow. From these observations along with the embryological correlation of choriocapillaris development, a possibility of an abnormality preventing proper fenestration of the choriocapillaris along the horizontal raphe being responsible for this anomaly is suggested.

  5. Pitfalls in colour photography of choroidal tumours.

    Science.gov (United States)

    Schalenbourg, A; Zografos, L

    2013-02-01

    Colour imaging of fundus tumours has been transformed by the development of digital and confocal scanning laser photography. These advances provide numerous benefits, such as panoramic images, increased contrast, non-contact wide-angle imaging, non-mydriatic photography, and simultaneous angiography. False tumour colour representation can, however, cause serious diagnostic errors. Large choroidal tumours can be totally invisible on angiography. Pseudogrowth can occur because of artefacts caused by different methods of fundus illumination, movement of reference blood vessels, and flattening of Bruch's membrane and sclera when tumour regression occurs. Awareness of these pitfalls should prevent the clinician from misdiagnosing tumours and wrongfully concluding that a tumour has grown.

  6. Pitfalls in colour photography of choroidal tumours

    Science.gov (United States)

    Schalenbourg, A; Zografos, L

    2013-01-01

    Colour imaging of fundus tumours has been transformed by the development of digital and confocal scanning laser photography. These advances provide numerous benefits, such as panoramic images, increased contrast, non-contact wide-angle imaging, non-mydriatic photography, and simultaneous angiography. False tumour colour representation can, however, cause serious diagnostic errors. Large choroidal tumours can be totally invisible on angiography. Pseudogrowth can occur because of artefacts caused by different methods of fundus illumination, movement of reference blood vessels, and flattening of Bruch's membrane and sclera when tumour regression occurs. Awareness of these pitfalls should prevent the clinician from misdiagnosing tumours and wrongfully concluding that a tumour has grown. PMID:23238442

  7. Modeling of Laser Induced Damage in NIF UV Optics

    Energy Technology Data Exchange (ETDEWEB)

    Feit, M D; Rubenchik, A M

    2001-02-21

    Controlling damage to nominally transparent optical elements such as lenses, windows and frequency conversion crystals on high power lasers is a continuing technical problem. Scientific understanding of the underlying mechanisms of laser energy absorption, material heating and vaporization and resultant mechanical damage is especially important for UV lasers with large apertures such as NIF. This LDRD project was a single year effort, in coordination with associated experimental projects, to initiate theoretical descriptions of several of the relevant processes. In understanding laser damage, we distinguish between damage initiation and the growth of existent damage upon subsequent laser irradiation. In general, the effect of damage could be ameliorated by either preventing its initiation or by mitigating its growth. The distinction comes about because initiation is generally due to extrinsic factors such as contaminants, which provide a means of local laser energy absorption. Thus, initiation tends to be local and stochastic in nature. On the other hand, the initial damaging event appears to modify the surrounding material in such a way that multiple pulse damage grows more or less regularly. More exactly, three ingredients are necessary for visible laser induced damage. These are adequate laser energy, a mechanism of laser energy absorption and mechanical weakness. For damage growth, the material surrounding a damage site is already mechanically weakened by cracks and probably chemically modified as well. The mechanical damage can also lead to electric field intensification due to interference effects, thus increasing the available laser energy density. In this project, we successfully accounted for the pulselength dependence of damage threshold in bulk DKDP crystals with the hypothesis of small absorbers with a distribution of sizes. We theoretically investigated expected scaling of damage initiation craters both to baseline detailed numerical simulations

  8. Laser-induced multi-energy processing in diamond growth

    Science.gov (United States)

    Xie, Zhiqiang

    Laser-induced multi-energy processing (MEP) introduces resonant vibrational excitations of precursor molecules to conventional chemical vapor deposition methods for material synthesis. In this study, efforts were extended to explore the capability of resonant vibrational excitations for promotion of energy efficiency in chemical reactions, for enhancement of diamond deposition, and for control of chemical reactions. The research project mainly focused on resonant vibrational excitations of precursor molecules using lasers in combustion flame deposition of diamond, which led to: 1) promotion of chemical reactions; 2) enhancement of diamond growth with higher growth rate and better crystallizations; 3) steering of chemical reactions which lead to preferential growth of {100}-oriented diamond films and crystals; and 4) mode-selective excitations of precursor molecules toward bond-selective control of chemical reactions. Diamond films and crystals were deposited in open air by combustion flame deposition through resonant vibrational excitations of precursor molecules, including ethylene (C2H4) and propylene (C3H 6). A kilowatt wavelength-tunable CO2 laser with spectral range from 9.2 to 10.9 microm was tuned to match vibrational modes of the precursor molecules. Resonant vibrational excitations of these molecules were achieved with high energy efficiency as compared with excitations using a common CO2 laser (fixed wavelength at 10.591microm). With resonant vibrational excitations, the diamond growth rate was increased; diamond quality was promoted; diamond crystals with lengths up to 5 mm were deposited in open air; preferential growth of {100}-oriented diamond films and single crystals was achieved; mode-selective excitations of precursor molecules were investigated toward control of chemical reactions. Optical emission spectroscopy (OES), mass spectrometry (MS), and molecular dynamic simulations were conducted to obtain an in-depth understanding of the resonant

  9. Correlation between clinical and histological features in a pig model of choroidal neovascularization

    DEFF Research Database (Denmark)

    Lassota, Nathan; Kiilgaard, Jens Folke; Prause, Jan Ulrik

    2006-01-01

    To analyse the histological changes in the retina and the choroid in a pig model of choroidal neovascularization (CNV) and to correlate these findings with fundus photographic and fluorescein angiographic features.......To analyse the histological changes in the retina and the choroid in a pig model of choroidal neovascularization (CNV) and to correlate these findings with fundus photographic and fluorescein angiographic features....

  10. Liquid jet formation through the interactions of a laser-induced bubble and a gas bubble

    Science.gov (United States)

    Han, Bing; Liu, Liu; Zhao, Xiong-Tao; Ni, Xiao-Wu

    2017-10-01

    The mechanisms of the liquid jet formation from the interaction of the laser-induced and gas bubble pair are investigated and compared with the jet formation from the interaction of the laser-induced anti-phase bubble pair. The strobe photography experimental method and numerical simulations are implemented to obtain the parameter space of the optimum liquid jet, i.e. highest speed and lowest diameter. It is found that due to the enhanced "catapult effect", which is induced by the protrusion of the first bubble into the second bubble and the flip back of the elongated part of the first bubble, the optimum liquid jet of the second bubble of the laser-induced anti-phase bubble pair compared to that of the laser-induced and gas bubble pair is 54 %, 65 % and 11 % faster in speed, and 4 %, 44 % and 64 % smaller in diameter, for the 500 μm, 50 μm and 5 μm sized bubbles, respectively. The optimum dimensionless distance for the optimum jet of the laser-induced and the gas bubble is around 0.7, when the maximum bubble radius increases from ˜ 5μm to ˜500 μm, which is different from the laser-induced anti-phase bubble pairs. Besides, the optimum jet of the laser-induced bubble appeared when the bubbles are equal sized, while that of the gas bubble is independent of the relative bubble size, i.e. the liquid jet of the gas bubble has higher robustness in real liquid jet assisted applications when the laser-induced bubble size varies. However, the jet of bubble 2 could maintain a high speed (20 m/s - 35 m/s) and a low diameter (˜5 % of the maximum bubble diameter) over a big range of the dimensionless distance (0.6 - 0.9) for both of the 50 μm and 500 μm sized laser-induced equal sized anti-phase bubble pairs.

  11. Generation and expansion of laser-induced plasma as a spectroscopic emission source

    Science.gov (United States)

    Yu, Jin; Ma, Qianli; Motto-Ros, Vincent; Lei, Wenqi; Wang, Xiaochun; Bai, Xueshi

    2012-12-01

    Laser-induced plasma represents today a widespread spectroscopic emission source. It can be easily generated using compact and reliable nanosecond pulsed laser on a large variety of materials. Its application for spectrochemical analysis for example with laser-induced breakdown spectroscopy (LIBS) has become so popular that one tends to forget the complex physical and chemical processes leading to its generation and governing its evolution. The purpose of this review article is to summarize the backgrounds necessary to understand and describe the laser-induced plasma from its generation to its expansion into the ambient gas. The objective is not to go into the details of each process; there are numerous specialized papers and books for that in the literature. The goal here is to gather in a same paper the essential understanding elements needed to describe laser-induced plasma as results from a complex process. These elements can be dispersed in several related but independent fields such as laser-matter interaction, laser ablation of material, optical and thermodynamic properties of hot and ionized gas, or plasma propagation in a background gas. We believe that presenting the ensemble of understanding elements of laser-induced plasma in a comprehensive way and in limited pages of this paper will be helpful for further development and optimized use of the LIBS technique. Experimental results obtained in our laboratory are used to illustrate the studied physical processes each time such illustration becomes possible and helpful.

  12. Fibrosis of the Choroid Plexus Filtration Membrane

    Science.gov (United States)

    Parratt, John D. E.; Kirwan, Paul D.

    2016-01-01

    We report a previously undescribed inflammatory lesion consisting of deposition of activated complement (C3d and C9neo) in association with major histocompatibility complex type II (MHC2)-positive activated microglia in choroid plexus villi exhibiting classical fibrous thickening of the pericapillary filtration membrane. The proportion of villi affected ranged from 5% to 90% in 56 adult subjects with diseases of the CNS and 11 subjects with no preexisting disease of the CNS. In 3 of the 4 children studied, 2% or less of examined villi showed stromal thickening, complement deposition, and the presence of MHC2-positive microglia; in adults, the proportion of villi affected increased with age. Other features of the lesion included loss of capillaries and failure by macrophages to clear extracellular particulate electron-dense material by clathrin-mediated phagocytosis. This choroid plexus lesion may relate pathogenetically to age-related macular degeneration and to Alzheimer disease, 2 other conditions with no known risk factors other than increasing age. All 3 conditions are characterized by the presence of damaged capillaries, inflammatory extracellular aggregates of mixed molecular composition and defective clearance of the deposits by macrophages. PMID:27444353

  13. Attenuation corrections for in-cylinder NO LIF measurements in a heavy-duty Diesel engine

    NARCIS (Netherlands)

    Verbiezen, K.; Klein Douwel, R.J.H.; Vliet, A.P. van; Donkerbroek, A.J.; Meerts, W.L.; Dam, N.J.; Meulen, J.J. ter

    2006-01-01

    Quantification of the nitric oxide (NO) concentration inside the cylinder of a Diesel engine by means of laser-induced fluorescence (LIF) measurements requires, amongst others, knowledge of the attenuation of the ultraviolet radiation involved. We present a number of laser diagnostic techniques to

  14. Polypoidal Choroidal Vasculopathy Associated with Optic Disc Coloboma

    Directory of Open Access Journals (Sweden)

    Yumiko Nakano

    2018-01-01

    Full Text Available Purpose: To report a case of polypoidal choroidal vasculopathy associated with optic disc coloboma. Methods: Case report. Results: A 50-year-old woman presented with optic disc coloboma and retinochoroidal coloboma associated with subretinal hemorrhage and serous retinal detachment (SRD in her left eye. Optical coherence tomography (OCT confirmed SRD at the macula and showed a sharply elevated retinal epithelial detachment at the choroidal excavation. OCT also revealed choroidal cavitation along the temporal side of the optic coloboma. Fluorescein angiography showed hyperfluorescent dye leakage and indocyanine green angiography revealed polypoidal lesions. We diagnosed polypoidal choroidal vasculopathy (PCV. PCV was located at the end of the choroidal cavitation. Her left eye was treated with an intraocular injection of the anti-vascular endothelial growth factor aflibercept (2 mg. Photodynamic therapy was performed using the standard protocol 1 week after the intravitreal application of aflibercept. One month after the combined treatment, OCT showed completely resolved SRD and her symptoms disappeared. Her best-corrected visual acuity remained stable and no recurrence was found during a 12-month follow-up period. Conclusion: PCV associated with optic disc coloboma has not been previously reported. The morphological abnormality of choroidal cavitation and choroidal excavation connecting with optic disc coloboma may contribute to the development of PCV in this case.

  15. Laser-induced fluorescence imaging of coronary arteries for open-heart surgery applications

    Science.gov (United States)

    Taylor, Roderick S.; Gladysz, D.; Brown, Derek W.; Higginson, Lyall A. J.

    1991-07-01

    A technique utilizing laser induced fluorescence has been developed to obtain direct real-time imaging of the coronary artery network for open heart surgery applications. Both excimer pumped dye and cw argon-ion laser radiation transmitted through a fused silica fiber were used as laser sources to irradiate swine, bovine, and human cadaver hearts whose coronary arteries had been injected with strongly fluorescent dyes. The laser induces fluorescence originating from within the coronary arteries and detected by the surgeon's eye, allows the entire coronary network to be directly viewed. A comparison between laser induced fluorescence and the use of direct visual inspection of arteries following injection of the dye Cardio-Green(R) as well as conventional thermal imaging is presented. The limitations imposed on each technique by layers of fat on top of the coronary arteries are also described. The possibility of using these techniques to detect mechanical or laser beam perforations during laser endarterectomy procedures is discussed.

  16. Development of Laser-Induced Fluorescence Diagnostic for the Paul Trap Simulator Experiment

    CERN Document Server

    Chung, Moses; Efthimion, Philip; Gilson, Erik P; Majeski, Richard; Startsev, Edward

    2005-01-01

    The Paul Trap Simulator Experiment (PTSX) is a cylindrical Paul trap whose purpose is to simulate the nonlinear dynamics of intense charged particle beam propagation in alternating-gradient magnetic transport systems. For the in-situ measurement of the transverse ion density profile in the PTSX device, which is essential for the study of beam mismatch and halo particle production, a laser-induced fluorescence diagnostic system is being developed. Instead of cesium, which has been used in the initial phase of the PTSX experiment, barium has been selected as the preferred ion for the laser-induced fluorescence diagnostic. The installation of the barium ion source and the characterization of the tunable dye laser system are discussed. The design of the collection optics with an intensified CCD camera system is also discussed. Finally, initial test results using the laser-induced fluorescence diagnostic will be presented.

  17. Photophysics of Laser Dye-Doped Polymer Membranes for Laser-Induced Fluorescence Photogrammetry

    Science.gov (United States)

    Dorrington, Adrian A.; Jones, Thomas W.; Danehy, Paul M.

    2004-01-01

    Laser-induced fluorescence target generation in dye-doped polymer films has recently been introduced as a promising alternative to more traditional photogrammetric targeting techniques for surface profiling of highly transparent or reflective membrane structures. We investigate the photophysics of these dye-doped polymers to help determine their long-term durability and suitability for laser-induced fluorescence photogrammetric targeting. These investigations included experimental analysis of the fluorescence emission pattern, spectral content, temporal lifetime, linearity, and half-life. Results are presented that reveal an emission pattern wider than normal Lambertian diffuse surface scatter, a fluorescence time constant of 6.6 ns, a pump saturation level of approximately 20 micro J/mm(exp 2), and a useful lifetime of more than 300,000 measurements. Furthermore, two demonstrations of photogrammetric measurements by laser-induced fluorescence targeting are presented, showing agreement between photogrammetric and physically measured dimensions within the measurement scatter of 100 micron.

  18. Acoustic signal characteristics of laser induced cavitation in DDFP droplet: Spectrum and time-frequency analysis.

    Science.gov (United States)

    Feng, Yi; Qin, Dui; Zhang, Jun; Ma, Chenxiang; Wan, Mingxi

    2015-01-01

    Cavitation has great application potential in microvessel damage and targeted drug delivery. Concerning cavitation, droplet vaporization has been widely investigated in vitro and in vivo with plasmonic nanoparticles. Droplets with a liquid dodecafluoropentane (DDFP) core enclosed in an albumin shell have a stable and simple structure with good characteristics of laser absorbing; thus, DDFP droplets could be an effective aim for laser-induced cavitation. The DDPF droplet was prepared and perfused in a mimic microvessel in the optical microscopic system with a passive acoustic detection module. Three patterns of laser-induced cavitation in the droplets were observed. The emitted acoustic signals showed specific spectrum components at specific time points. It was suggested that a nanosecond laser pulse could induce cavitation in DDPF droplets, and specific acoustic signals would be emitted. Analyzing its characteristics could aid in monitoring the laser-induced cavitation process in droplets, which is meaningful to theranostic application.

  19. Choroid plexus papilloma in a beluga whale (Delphinapterus leucas).

    Science.gov (United States)

    Thomas, Christian; Mergl, June; Gehring, Erica; Paulus, Werner; Martineau, Daniel; Hasselblatt, Martin

    2016-07-01

    We report herein a choroid plexus papilloma in a beluga whale (Delphinapterus leucas). This case was positive for choroid plexus tumor marker Kir7.1 on immunohistochemistry. These results and the high conservation of Kir7.1 across species at the amino acid sequence level strongly suggest that antibodies directed against Kir7.1 not only can be employed for the diagnosis of choroid plexus tumors in cetaceans, but are also likely to be diagnostically useful in other animal species. © 2016 The Author(s).

  20. Laser-induced synthesis and decay of Tritium under exposure of solid targets in heavy water

    CERN Document Server

    Barmina, E V; Timashev, S F; Shafeev, G A

    2013-01-01

    The processes of laser-assisted synthesis of Tritium nuclei and their laser-induced decay in cold plasma in the vicinity of solid targets (Au, Ti, Se, etc.) immersed into heavy water are experimentally realized at peak laser intensity of 10E10-10E13 Watts per square centimeter. Initial stages of Tritium synthesis and their laser-induced beta-decay are interpreted on the basis of non-elastic interaction of plasma electrons having kinetic energy of 5-10 eV with nuclei of Deuterium and Tritium, respectively.

  1. Benefits and applications of laser-induced sparks in real scale model measurements

    DEFF Research Database (Denmark)

    Gómez-Bolaños, Javier; Delikaris-Manias, Symeon; Pulkki, Ville Topias

    2015-01-01

    distributed sparks. The source steering direction was scanned across the horizontal and vertical plane to assess the origin of early reflections. The results confirm that the characteristics of the laser-induced spark outperform those of typical sources. Its monopole characteristics enable the authors......The characteristics of using a laser-induced spark as a monopole source in scale model measurements were assessed by comparison with an electric spark and a miniature spherical loudspeaker. Room impulse responses of first order directivity sources were synthesized off-line using six spatially...

  2. Probing autoionizing states of molecular oxygen with XUV transient absorption: Electronic-symmetry-dependent line shapes and laser-induced modifications

    Science.gov (United States)

    Liao, Chen-Ting; Li, Xuan; Haxton, Daniel J.; Rescigno, Thomas N.; Lucchese, Robert R.; McCurdy, C. William; Sandhu, Arvinder

    2017-04-01

    We used extreme ultraviolet (XUV) transient absorption spectroscopy to study the autoionizing Rydberg states of oxygen in an electronically- and vibrationally-resolved fashion. XUV pulse initiates molecular polarization and near-infrared pulse perturbs its evolution. Transient absorption spectra show positive optical-density (OD) change in the case of n s σg and n d πg autoionizing states of oxygen and negative OD change for n d σg states. Multiconfiguration time-dependent Hartree-Fock (MCTDHF) calculations are used to simulate the transient absorption and the resulting spectra and temporal evolution agree with experimental observations. We model the effect of near-infrared perturbation on molecular polarization and find that the laser-induced phase-shift model agrees with the experimental and MCTDHF results, while the laser-induced attenuation model does not. We relate the electronic-state-symmetry-dependent sign of the OD change to the Fano parameters of the static absorption line shapes.

  3. SU-E-J-161: Inverse Problems for Optical Parameters in Laser Induced Thermal Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Fahrenholtz, SJ; Stafford, RJ; Fuentes, DT [UT MD Anderson Cancer Center, Houston, TX (United States); UT Graduate School of Biomedical Sciences, Houston, TX (United States)

    2014-06-01

    Purpose: Magnetic resonance-guided laser-induced thermal therapy (MRgLITT) is investigated as a neurosurgical intervention for oncological applications throughout the body by active post market studies. Real-time MR temperature imaging is used to monitor ablative thermal delivery in the clinic. Additionally, brain MRgLITT could improve through effective planning for laser fiber's placement. Mathematical bioheat models have been extensively investigated but require reliable patient specific physical parameter data, e.g. optical parameters. This abstract applies an inverse problem algorithm to characterize optical parameter data obtained from previous MRgLITT interventions. Methods: The implemented inverse problem has three primary components: a parameter-space search algorithm, a physics model, and training data. First, the parameter-space search algorithm uses a gradient-based quasi-Newton method to optimize the effective optical attenuation coefficient, μ-eff. A parameter reduction reduces the amount of optical parameter-space the algorithm must search. Second, the physics model is a simplified bioheat model for homogeneous tissue where closed-form Green's functions represent the exact solution. Third, the training data was temperature imaging data from 23 MRgLITT oncological brain ablations (980 nm wavelength) from seven different patients. Results: To three significant figures, the descriptive statistics for μ-eff were 1470 m{sup −1} mean, 1360 m{sup −1} median, 369 m{sup −1} standard deviation, 933 m{sup −1} minimum and 2260 m{sup −1} maximum. The standard deviation normalized by the mean was 25.0%. The inverse problem took <30 minutes to optimize all 23 datasets. Conclusion: As expected, the inferred average is biased by underlying physics model. However, the standard deviation normalized by the mean is smaller than literature values and indicates an increased precision in the characterization of the optical parameters needed to plan MRg

  4. Role of Intravitreal Antivascular Endothelial Growth Factor Injections for Choroidal Neovascularization due to Choroidal Osteoma

    Directory of Open Access Journals (Sweden)

    Ahmad M. Mansour

    2014-01-01

    Full Text Available We treated 26 eyes of 25 young patients having a mean age of 30 years with intravitreal vascular endothelial growth factor (VEGF inhibitor for choroidal new vessel (CNV formation overlying choroidal osteoma over a mean follow-up of 26 months. Mean number of injections was 2.4 at 6 months, 3.2 at 12 months, and 5.5 at 24 months. CNV was subfoveal in 14 eyes, juxtafoveal in 5, extrafoveal in 5, and peripapillary in 2. By paired comparison, mean decrease from baseline was 119.7 microns at 6 months (n=15; P=0.001, 105.3 microns at 1 year (n=10; P=0.03, and 157.6 microns at 2 years (n=7; P=0.08. BCVA improved by 3.3 lines at 6 months after therapy (n=26; P<0.001, 2.8 lines (n=20; P=0.01 at 1 year, and 3.1 lines (n=13; P=0.049 at 2 years. We conclude that intravitreal anti-VEGF injections improve vision in majority of eyes with CNV from choroidal osteoma.

  5. Choroidal neovascularisation on optical coherence tomography angiography in punctate inner choroidopathy and multifocal choroiditis.

    Science.gov (United States)

    Levison, Ashleigh L; Baynes, Kimberly M; Lowder, Careen Y; Kaiser, Peter K; Srivastava, Sunil K

    2017-05-01

    To describe the findings seen on optical coherence tomography angiography (OCTA) in patients with punctate inner choroidopathy (PIC) and multifocal choroiditis and panuveitis (MCP) complicated by choroidal neovascular membranes. This was an Institutional Review Board-approved prospective, descriptive case series. 12 patients with PIC and MCP complicated by choroidal neovascularisation (CNV) were included. Each patient underwent slit-lamp examination by a uveitis specialist followed by conventional spectral domain OCT imaging of the macula. OCTA images of the macula were then obtained. 12 patients were enrolled in the study, out of which 9 patients were followed longitudinally. CNV was identified in 11 of the 12 patients. In all patients where fluorescein angiography (FA) was inconclusive for presence of CNV, OCTA identified CNV. Various lesions on OCT suggestive of activity correlated with changes in the vascular structure of OCTA to confirm suspicion of clinical activity. In patients with PIC and MCP complicated by CNV, OCTA successfully identified underlying CNV. Given the difficulty of differentiating inflammatory lesions from early CNV on OCT and FA, OCTA may provide a valuable method of monitoring patients with posterior uveitis highly correlated with development of CNV. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  6. Surgical induction of choroidal neovascularization in a porcine model

    DEFF Research Database (Denmark)

    Lassota, Nathan; Kiilgaard, Jens Folke; Prause, Jan Ulrik

    2007-01-01

    PURPOSE: To develop a reproducible surgical technique for the induction of choroidal neovascularization (CNV) in the subretinal space of porcine eyes and to analyse the resulting CNV clinically and histologically. METHODS: Two different modifications of a surgical technique previously described...

  7. Gelsolin Restores Aβ-Induced Alterations in Choroid Plexus Epithelium

    Directory of Open Access Journals (Sweden)

    Teo Vargas

    2010-01-01

    Full Text Available Histologically, Alzheimer's disease (AD is characterized by senile plaques and cerebrovascular amyloid deposits. In previous studies we demonstrated that in AD patients, amyloid-β (Aβ peptide also accumulates in choroid plexus, and that this process is associated with mitochondrial dysfunction and epithelial cell death. However, the molecular mechanisms underlying Aβ accumulation at the choroid plexus epithelium remain unclear. Aβ clearance, from the brain to the blood, involves Aβ carrier proteins that bind to megalin, including gelsolin, a protein produced specifically by the choroid plexus epithelial cells. In this study, we show that treatment with gelsolin reduces Aβ-induced cytoskeletal disruption of blood-cerebrospinal fluid (CSF barrier at the choroid plexus. Additionally, our results demonstrate that gelsolin plays an important role in decreasing Aβ-induced cytotoxicity by inhibiting nitric oxide production and apoptotic mitochondrial changes. Taken together, these findings make gelsolin an appealing tool for the prophylactic treatment of AD.

  8. Gelsolin Restores Aβ-Induced Alterations in Choroid Plexus Epithelium

    Science.gov (United States)

    Vargas, Teo; Antequera, Desiree; Ugalde, Cristina; Spuch, Carlos; Carro, Eva

    2010-01-01

    Histologically, Alzheimer's disease (AD) is characterized by senile plaques and cerebrovascular amyloid deposits. In previous studies we demonstrated that in AD patients, amyloid-β (Aβ) peptide also accumulates in choroid plexus, and that this process is associated with mitochondrial dysfunction and epithelial cell death. However, the molecular mechanisms underlying Aβ accumulation at the choroid plexus epithelium remain unclear. Aβ clearance, from the brain to the blood, involves Aβ carrier proteins that bind to megalin, including gelsolin, a protein produced specifically by the choroid plexus epithelial cells. In this study, we show that treatment with gelsolin reduces Aβ-induced cytoskeletal disruption of blood-cerebrospinal fluid (CSF) barrier at the choroid plexus. Additionally, our results demonstrate that gelsolin plays an important role in decreasing Aβ-induced cytotoxicity by inhibiting nitric oxide production and apoptotic mitochondrial changes. Taken together, these findings make gelsolin an appealing tool for the prophylactic treatment of AD. PMID:20369065

  9. Diagnosis of Choroidal Melanoma in Dense Asteroid Hyalosis.

    Science.gov (United States)

    Motiani, Meghna V; McCannel, Colin A; Almanzor, Robert; McCannel, Tara A

    2017-01-01

    To demonstrate the utility of Optos ultra-wide field imaging in the diagnosis and management of choroidal melanoma in the setting of asteroid hyalosis. Observational case report. A 52-year-old female was referred for evaluation of floaters, photopsias, and blurry vision in the right eye. Clinical examination revealed dense asteroid hyalosis obscuring the fundus, and a limited view of a pigmented choroidal lesion in the nasal periphery. Optos ultra-wide field fluorescein angiography and ultrasonography facilitated the diagnosis of a choroidal melanoma. The patient underwent Iodine-125 brachytherapy for local tumor control and excellent tumor response was confirmed with serial follow-up Optos imaging and ultrasonography. Ultra-wide field fundus fluorescein angiography facilitated the diagnosis of a choroidal melanoma, which was obscured by dense asteroid hyalosis, allowing for local tumor control with brachytherapy. Optos wide-field imaging may be a valuable tool for detecting potentially life-threatening lesions in the setting of asteroid hyalosis.

  10. Keratoconus associated with choroidal neovascularization: a case report

    Directory of Open Access Journals (Sweden)

    Oh Joo

    2010-02-01

    Full Text Available Abstract Introduction Keratoconus and choroidal neovascularization can occur as a result of dysfunction of the epithelium and its basement membrane. Case presentation A 17-year-old Asian man, who was diagnosed with myopic choroidal neovascularization in both eyes and who subsequently underwent intravitreal injection of ranibizumab (Lucentis® five times over six months, presented with further vision decrease and pain in his right eye. Examination showed corneal steepening and stromal edema in the inferocentral cornea of his right eye, both of which were indicative of advanced keratoconus with acute hydrops. Corneal topography also showed features consistent with keratoconus in his left eye. Fluorescein angiography and optical coherence tomography revealed choroidal neovascularization-associated subretinal hemorrhages and lacquer cracks in both eyes. Conclusion Keratoconus and choroidal neovascularization, possibly resulting from dysfunction of the epithelium and its basement membrane, can occur together in the same individual. This would suggest a possible connection in pathogenesis between these two conditions.

  11. Optical coherence tomography angiography in pediatric choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Chiara Veronese

    2016-07-01

    Conclusion: Distinct choroidal neovascular patterns were visualized in these two cases of pediatric CNV when compared to adult subtypes. OCTA is a noninvasive imaging modality capable of evaluating and characterizing pediatric CNV and their associated vascular patterns.

  12. Morphological features of choroidal metastases: An OCT analysis

    Directory of Open Access Journals (Sweden)

    Ludovico Iannetti

    2013-01-01

    Full Text Available The morphological characteristics and retinal changes of chroidal metastases using Spectral Domain OCT are described in a case with primary lung adenocarcinoma and secondary choroidal involvement.

  13. Beals–Hecht syndrome and choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Roberto Gallego-Pinazo

    2010-07-01

    Full Text Available Roberto Gallego-Pinazo1, Ruth López-Lizcano1, José María Millán2,3, J Fernando Arevalo5, J Luis Mullor6, Manuel Díaz-Llopis1,3,41Department of Ophthalmology, 2Department of Genetics, Unit of Experimental Opthalmology, Hospital Universitario La Fe, Valencia, Spain; 3Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER, Valencia, Spain; 4Faculty of Medicine, University of Valencia, Valencia, Spain; 5Retina and Vitreous Service, Clínica Oftalmológica Centro Caracas, Caracas, Venezuela; 6Unit of Experimental Opthalmology, Fundación Parala Investigación del Hospital La Fe, Valencia, SpainPurpose: To describe a case of choroidal neovascularization (CNV in a female diagnosed with Beals–Hecht syndrome.Methods: A retrospective, interventional case is described in a 26-year-old female complaining of metamorphopsia and visual loss in her left eye (counting fingers. The fluorescein angiogram and the optical coherence tomography supported the diagnosis of CNV. Intravitreal ranibizumab was administered.Results: After the third intravitreal ranibizumab, her visual acuity improved to 0.8 and the morphology of the macular area was restored.Conclusions: To our knowledge this is the first report of CNV in Beals–Hecht syndrome treated with ranibizumab. Self-monitoring by periodically performing Amsler grid test is strongly recommended in these patients in order to achieve an early diagnosis of eventual CNV and avoid visual acuity loss.Keywords: Beals–Hecht syndrome, connective tissue disease, choroidal neovascularization, ranibizumab

  14. Retinal and choroidal thickness in myopic anisometropia.

    Science.gov (United States)

    Vincent, Stephen J; Collins, Michael J; Read, Scott A; Carney, Leo G

    2013-04-03

    We compared the retinal thickness (RT) and choroidal thickness (ChT) between the fellow eyes of nonamblyopic myopic anisometropes. The eyes of 22 nonamblyopic myopic anisometropes (≥ 1 diopter [D] spherical equivalent refraction [SER] anisometropia) were examined using spectral domain optical coherence tomography (SD-OCT). Customized software was used to register, align, and average multiple foveal OCT B-scan images from each subject to enhance image quality. Two independent masked observers manually determined the RT and ChT from each SD-OCT image up to 2.5 mm nasal and temporal to the fovea. Axial length (AXL) was measured using optical low coherence biometry during relaxed accommodation. The mean SER anisometropia was 1.74 ± 0.95 D and the mean interocular AXL difference was 0.58 ± 0.41 mm. There was no significant difference in foveal RT between the fellow eyes (P > 0.05). Mean subfoveal ChT was significantly thinner in the more myopic eye (252 ± 46 μm) compared to the fellow, less myopic eye (286 ± 58 μm) (P < 0.001). There was a moderate correlation between the interocular difference in subfoveal ChT and the interocular difference in AXL (r = -0.50, P < 0.01). Asian anisometropes displayed more regionally symmetrical (nasal-temporal) interocular differences in ChT profile compared to Caucasians. RT was similar between the fellow eyes of myopic anisometropes; however, the subfoveal choroid was significantly thinner in the more myopic (longer) eye of this anisometropic cohort. The interocular asymmetry in ChT correlated with the interocular difference in AXL.

  15. Patterns of tumor initiation in choroidal melanoma.

    Science.gov (United States)

    Li, W; Judge, H; Gragoudas, E S; Seddon, J M; Egan, K M

    2000-07-15

    This study attempts to document the occurrence of tumors with respect to clock hour location and distance from the macula and to evaluate tumor location in relation to retinal topography and light dose distribution on the retinal sphere. Analysis of patterns of tumor initiation may provide new evidence to clarify the controversy regarding the possible light-related etiology of choroidal melanoma. Incident cases of choroidal and ciliary body melanoma in Massachusetts residents diagnosed between 1984 and 1993 were the basis for analysis. Conventional fundus drawings and photos were used to assess the initiation site of each tumor. The initiation site was defined as the intersect between the largest tumor diameter and the largest perpendicular diameter of the tumor. Initiation sites were recorded using spherical coordinates. The retinal sphere was divided into 61 mutually exclusive sectors defined according to clock hour and anteroposterior distance from the macula. Rates of initiation were computed for each sector, overall, and according to gender and other clinical factors. Results were similar in left and right eyes; therefore, these were combined in analysis. Tumor initiation had a predilection for the macula (P preference was observed (P = 0.63). However, the parafoveal zone showed a strong circular trend (P eyes, respectively. Concentric zone location did not vary by gender (P = 0.93) or laterality (P = 0.78). However, posterior location was associated with light iris color (P = 0.01). Tumor diameters were largest in the peripheral region of the fundus and smallest in the macular and ciliary body zone (P color (P = 0.84), or tumor diameter (P = 0.73). Results suggest that tumor initiation is not uniformly distributed, with rates of occurrence concentrated in the macular area and decreasing monotonically with distance from the macula to the ciliary body. This pattern is consistent with the retinal topography and correlates positively with the dose distribution of

  16. The effect of strabismus surgery on choroidal thickness.

    Science.gov (United States)

    Inan, Kamil; Niyaz, Leyla

    2017-09-07

    To determine the effects of strabismus surgery on choroidal thickness. This was a prospective randomized study. The measurements of subfoveal and macular choroidal thickness of patients who underwent strabismus surgery were obtained by enhanced depth imaging optic coherence tomography. The patients were grouped as patients who had 1 horizontal muscle surgery (group 1), 1 oblique muscle surgery (group 2), 2 horizontal muscle surgeries (group 3), or 1 horizontal and 1 oblique muscle surgery (group 4). Choroidal thickness of the patients was measured preoperatively and on the postoperative first day, second week, first month, and third month. Choroidal thickness was measured at subfoveal area (S) and at the nasal (N1, N2) and temporal (T1, T2) fovea with 500-μm intervals. The average age of the 37 patients was 15.59 ± 13.84 years. In preoperative and postoperative first day comparison, a decrease in choroidal thickness was found in all areas in group 1. In group 2, a significant decrease was found in N2, N1, and S values. In group 3, a significant decrease was found in N2, N1, and T2 values. In group 4, a significant decrease was found in N1 value. The second week comparison of all groups showed significant postoperative decrease in choroidal thickness in all areas. On the postoperative first month, a significant decrease in choroidal thickness was found only in the subfoveal area of group 1 and the N1 area of group 2. At the postoperative third month, there was no change in any group. Strabismus surgery causes a decrease in choroidal thickness in the early postoperative period.

  17. Effect of modified Zhu Jing prescriptions on the expression of VEGF in pathological myopia with choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Nan-Nan Tian

    2013-08-01

    Full Text Available AIM: To observe the effect of traditional medicine to the expression of vascular endothelium growth factor(VEGF, and explore the intervention effect to the pathological myopia with choroidal neovascularization(CNVthrough experimental model of lasers -induced CNV in guinea pigs with pathological myopia induced by form deprivation. METHODS: Fifteen of the forty-five 3-week old female guinea pigs were randomly selected as the blank control group, the rest 30 guinea pigs were using facemask to induce high myopia in 4 weeks, then randomly assigned to model group and treatment group, then induced CNV by different wavelength laser. The treatment group gavaged with modified Zhu Jing prescriptions while the control group was gavaged with distill water. 21 days after treatment, histopathologic choroidal flat mounts, HE stain,immunofluorescence stain and immuno- histochemistry for VEGF in the experimental eyes and control eyes were performed.RESULTS:All the 30 guinea pigs were successfully induced high myopia and the axial length of the right eyes were significantly greater than the non-facemask eyes and the eyes of control group. Immunofluorescence stain and immunohistochemistry for VEGF showed that the expression of VEGF of the treatment group was less than the model group. The average optical density(AODof the form deprivation eye in the treatment group(0.0589±0.0146was higher than that in the model group(0.0972±0.0507(PCONCLUSION: Modified Zhu Jing prescriptions has a positive effect to the reduction of the VEGF expression in the CNV with pathological myopia and thus it can inhibit the growth of CNV.

  18. Top down fabrication of organic nanocrystals by femtosecond laser induced transfer method

    NARCIS (Netherlands)

    Fang, Hong-Hua; Yang, Jie; Ding, Ran; Feng, Jing; Chen, Qi-Dai; Sun, Hong-Bo; Fang, Honghua

    2012-01-01

    We present the preparation of nanometer-size organic crystals using femtosecond laser induced forward transfer (Fs-LIFT) method. 1,4-Bis(4-methylstyryl)benzene (BSB-Me) nanocrystals are directly deposited on the substrate to form a nanocrystal film. Size and morphology as functions of applied laser

  19. The spatial resolution of the porcine multifocal electroretinogram for detection of laser-induced retinal lesions

    DEFF Research Database (Denmark)

    Kyhn, Maria Voss; Kiilgaard, Jens Folke; Scherfig, Erik

    2008-01-01

    This study aimed to investigate the spatial resolution of a porcine multifocal electroretinogram (mfERG) protocol by testing its ability to detect laser-induced retinal lesions. Furthermore, we wanted to describe time-dependent changes in implicit time and amplitude of the different mfERG peaks...

  20. Calculation and optimization of sample identification by laser induced breakdown spectroscopy via correlation analysis

    NARCIS (Netherlands)

    Lentjes, M.; Dickmann, K.; Meijer, J.

    2007-01-01

    Linear correlation analysis may be used as a technique for the identification of samples with a very similar chemical composition by laser induced breakdown spectroscopy. The spectrum of the “unknown” sample is correlated with a library of reference spectra. The probability of identification by

  1. Capillary electrophoresis with laser-induced fluorescence detection for fast and reliable apolipoprotein E genotyping

    NARCIS (Netherlands)

    Somsen, GW; Welten, HTME; Mulder, FP; Swart, CW; Kema, IP; de Jong, GJ

    2002-01-01

    The use of capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection for the rapid determination of apolipoprotein E (apoE) genotypes was studied. High resolution and sensitive detection of the concerned DNA restriction fragments was achieved using CE buffers with

  2. Standoff Detection of Explosives at 1 m using Laser Induced Breakdown Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Junjuri, R.; Myakalwar, A.K.; Gundawar, M.K.

    2017-01-01

    Roč. 67, č. 6 (2017), s. 623-630 ISSN 0011-748X Institutional support: RVO:67985882 Keywords : Laser induced breakdown spectroscopy * Multivariate analysis * Principal component analysis * Explosive detection Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.500, year: 2016

  3. Effects of thermo-plasmonics on laser-induced backside wet etching of silicate glass

    Science.gov (United States)

    Tsvetkov, M. Yu; Yusupov, V. I.; Minaev, N. V.; Timashev, P. S.; Golant, K. M.; Bagratashvili, V. N.

    2016-10-01

    The thermo-plasmonic effect (heat deposition via absorption of laser light by metal nanoparticles) is applied to substantially enhance the effectiveness and controllability of the microstructure formation by laser-induced backside wet etching (LIBWE). Experiments were carried out with silicate glass plates using a pulsed 527 nm wavelength laser and an aqueous solution of AgNO3 as a precursor of the Ag nanoparticles. Mechanisms of such thermo-plasmonic LIBWE (TP-LIBWE) versions are considered. They involve: laser-induced photo-thermal reducing of silver (Ag) and self-assembling of Ag nanoparticles in water and the water/glass interface; fast laser-induced overheating of a water and glass surface through the thermo-plasmonic effect; formation of highly reactive supercritical water that causes glass etching and crater formation; generation of steam-gas bubbles in a liquid. It is significant that the emergence of the Marangoni convection results in bubble retention in the focal point at the interface and the accumulation of nanoparticles on the surface of the laser-induced crater, as this facilitates the movement of the bubbles with captured Ag particles from the fluid volume in the crater region, and accelerates the formation of the area of strong ‘surface absorption’ of laser energy. All these mechanisms provide a highly efficient and reproducible process for laser microstructure formation on the surface of glass using a novel TP-LIBWE technique.

  4. Laser-induced breakdown spectra of Zn2 molecule in the violet region

    Indian Academy of Sciences (India)

    Laser-induced breakdown spectrum has been recorded in the region of 380-455 nm using second harmonics of Nd:YAG laser, computer-controlled TRIAX 320 M monochromator with a reciprocal linear dispersion .... Laser & Spectroscopy Laboratory, Department of Physics, University of Allahabad, Allahabad 211 002, India ...

  5. Work of adhesion in laser-induced delamination along polymer-metal interfaces

    NARCIS (Netherlands)

    Fedorov, A.; van Tijum, R.; Vellinga, W. P.; de Hosson, Jeff

    2007-01-01

    Laser-induced delamination is a recent technique aimed at characterizing adhesive strength of thin polymer coatings on metal substrates. A laser pulse is used to create a blister that initiates further delamination of the film under pressure. To process the experimental data a simple elastic model

  6. Plume expansion of a laser-induced plasma studied with the particle-in-cell method

    DEFF Research Database (Denmark)

    Ellegaard, Ole; Nedela, T; Urbassek, H

    2002-01-01

     The initial stage of laser-induced plasma plume expansion from a solid in vacuum and the effect of the Coulomb field have been studied. We have performed a one-dimensional numerical calculation by mapping the charge on a computational grid according to the particle-in-cell (PIC) method of Birdsall...

  7. Plume expansion of a laser-induced plasma studied with the particle-in-cell method

    DEFF Research Database (Denmark)

    Ellegaard, O.; Nedelea, T.; Schou, Jørgen

    2002-01-01

    The initial stage of laser-induced plasma plume expansion from a solid in vacuum and the effect of the Coulomb field have been studied. We have performed a one-dimensional numerical calculation by mapping the charge on a computational grid according to the particle-in-cell (PIC) method of Birdsall...

  8. Laser-induced forward transfer of intact, solid-phase inorganic materials

    NARCIS (Netherlands)

    Feinäugle, Matthias

    2014-01-01

    Laser-induced forward transfer (LIFT) is a technique for the micro- and nanofabrication of photonic, electronic and biomedical devices. Compared to conventional methods of device microfabrication, LIFT offers the unique features of transfer of functional and sensitive thin films with a minimum of

  9. Formation of nitric oxide in an industrial burner measured by 2-D laser induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, A.; Bombach, R.; Kaeppeli, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    We have performed two-dimensional Laser Induced Fluorescence (2-D LIF) measurements of nitric oxide and hydroxyl radical distributions in an industrial burner at atmospheric pressure. The relative 2-D LIF data of NO were set to an absolute scale by calibration with probe sampling combined with gas analysis. (author) 3 figs., 7 refs.

  10. Laser-Induced Breakdown Spectroscopy for Qualitative Analysis of Metals in Simulated Martian Soils

    Science.gov (United States)

    Mowry, Curtis; Milofsky, Rob; Collins, William; Pimentel, Adam S.

    2017-01-01

    This laboratory introduces students to laser-induced breakdown spectroscopy (LIBS) for the analysis of metals in soil and rock samples. LIBS employs a laser-initiated spark to induce electronic excitation of metal atoms. Ensuing atomic emission allows for qualitative and semiquantitative analysis. The students use LIBS to analyze a series of…

  11. High-resolution imaging of ejection dynamics in laser-induced forward transfer

    NARCIS (Netherlands)

    Pohl, Ralph; Visser, C.W.; Römer, Gerardus Richardus, Bernardus, Engelina; Sun, C.; Huis in 't Veld, Bert; Lohse, Detlef; Nakata, Yoshiki; Xianfan, Xianfan; Roth, Stephan; Neuenschwander, Beat

    2014-01-01

    Laser-induced Forward Transfer (LIFT) is a 3D direct-write method suitable for precision printing of various materials. As the ejection mechanism of picosecond LIFT has not been visualized in detail, the governing physics are not fully understood yet. Therefore, this article presents an experimental

  12. Printing Functional 3D Microdevices by Laser-Induced Forward Transfer

    NARCIS (Netherlands)

    Luo, Jun; Pohl, Ralph; Qi, Lehua; Römer, Gerardus Richardus, Bernardus, Engelina; Sun, Chao; Lohse, Detlef; Visser, C.W.

    2017-01-01

    Slender, out-of-plane metal microdevices are made in a new spatial domain, by using laser-induced forward transfer (LIFT) of metals. Here, a thermocouple with a thickness of 10 µm and a height of 250 µm, consisting of platinum and gold pillars is demonstrated. Multimaterial LIFT enables

  13. Laser-induced breakdown spectroscopy for quantification of heavy metals in soils and sediments

    CSIR Research Space (South Africa)

    Ambushe, AA

    2010-09-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS) will be used to determine the contents of heavy metals in soils and sediments. LIBS results will be compared with the results obtained by inductively coupled plasma-optical emission spectrometry (ICP...

  14. Study of mid IR fiber transmission and mode patterns under laser induced stimulated Brillouin scattering

    Science.gov (United States)

    Yu, C.; Chong, Yat C.; Zhou, Hongyi

    1990-01-01

    Mid IR fiber transmission and exit radiation mode patterns at various incident CO2 laser power levels appear to be effective diagnostic tools for monitoring laser induced stimulated Brillouin scattering in various mid IR fibers. Such processes are deemed to be essential mechanisms for fiber-optic amplifiers and switches as potential replacements of current repeaters and bistable devices.

  15. Laser-induced bound-state phases in high-order harmonic generation

    DEFF Research Database (Denmark)

    Etches, Adam; B. Gaarde, Mette; Bojer Madsen, Lars

    2012-01-01

    We present single-molecule and macroscopic calculations showing that laser-induced Stark shifts contribute significantly to the phase of high-order harmonics from polar molecules. This is important for orbital tomography, where phases of field-free dipole matrix elements are needed in order...

  16. [The Spectral Analysis of Laser-Induced Plasma in Laser Welding with Various Protecting Conditions].

    Science.gov (United States)

    Du, Xiao; Yang, Li-jun; Liu, Tong; Jiao, Jiao; Wang, Hui-chao

    2016-01-01

    The shielding gas plays an important role in the laser welding process and the variation of the protecting conditions has an obvious effect on the welding quality. This paper studied the influence of the change of protecting conditions on the parameters of laser-induced plasma such as electron temperature and electron density during the laser welding process by designing some experiments of reducing the shielding gas flow rate step by step and simulating the adverse conditions possibly occurring in the actual Nd : YAG laser welding process. The laser-induced plasma was detected by a fiber spectrometer to get the spectral data. So the electron temperature of laser-induced plasma was calculated by using the method of relative spectral intensity and the electron density by the Stark Broadening. The results indicated that the variation of protecting conditions had an important effect on the electron temperature and the electron density in the laser welding. When the protecting conditions were changed, the average electron temperature and the average electron density of the laser-induced plasma would change, so did their fluctuation range. When the weld was in a good protecting condition, the electron temperature, the electron density and their fluctuation were all low. Otherwise, the values would be high. These characteristics would have contribution to monitoring the process of laser welding.

  17. Laser-induced breakdown spectroscopy thickness measurements of films thinner than ablation rate

    Science.gov (United States)

    Nishijima, D.; Doerner, R. P.; Hollmann, E. M.; Miyamoto, M.

    2017-10-01

    A new laser-induced breakdown spectroscopy (LIBS) technique is proposed to measure the thickness of films thinner than the ablation rate. The film thickness dependence of the signal intensity is used as a calibration curve. It is demonstrated that calibration curves are successfully made for thin W films and (Fe, Cr, Ni) mixed-material films produced in a magnetron sputtering device.

  18. Ejection Regimes in Picosecond Laser-Induced Forward Transfer of Metals

    NARCIS (Netherlands)

    Pohl, Ralph; Visser, C.W.; Römer, Gerardus Richardus, Bernardus, Engelina; Lohse, Detlef; Sun, Chao; Huis in 't Veld, Bert

    2015-01-01

    Laser-induced forward transfer (LIFT) is a 3D direct-write method suitable for precision printing of various materials, including pure metals. To understand the ejection mechanism and thereby improve deposition, here we present visualizations of ejection events at high-spatial (submicrometer) and

  19. Imaging of the ejection process of nanosecond laser-induced forward transfer of gold

    NARCIS (Netherlands)

    Pohl, Ralph; Visser, C.W.; Römer, Gerardus Richardus, Bernardus, Engelina; Sun, Chao; Huis in 't Veld, Bert; Lohse, Detlef

    2014-01-01

    Laser-induced forward transfer is a direct-write process suitable for high precision 3D printing of several materials. However, the driving forces related to the ejection mechanism of the donor ma-terial are still under debate. So far, most of the experimental studies of nanosecond LIFT, are based

  20. Characterization of Metal Sprays Created by a Picosecond Laser-Induced Forward Transfer (LIFT) Process

    NARCIS (Netherlands)

    Pohl, Ralph; Römer, Gerardus Richardus, Bernardus, Engelina; Hoppenbrouwers, M.; Huis in 't Veld, Bert

    2012-01-01

    A new method to analyze and quantify results obtained with the Laser-Induced Forward Transfer (LIFT) process is presented. This experiment based characterization method was designed to investigate the spraying behavior of the LIFT process, that occurs in certain fluence regimes. This method was

  1. Nanoparticle detection in aqueous solutions using Raman and Laser Induced Breakdown Spectroscopy

    NARCIS (Netherlands)

    Sovago, M.; Buis, E.-J.; Sandtke, M.

    2013-01-01

    We show the chemical identification and quantification of the concentration and size of nanoparticle (NP) dispersions in aqueous solutions by using a combination of Raman Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS). The two spectroscopic techniques are applied to demonstrate the NP

  2. Analysis of irradiation processes for laser-induced periodic surface structures

    NARCIS (Netherlands)

    Eichstädt, J.; Huis in 't Veld, Bert

    2013-01-01

    The influence of errors on the irradiation process for laser-induced periodic surface structures (LIPSS) was studied theoretically with energy density simulations. Therefore an irradiation model has been extended by a selection of technical variations. The influence of errors has been found in a

  3. Laser-induced photochemical gas-phase reactions of vibrationally excited triplet molecules

    Science.gov (United States)

    Zalesskaya, G. A.; Yakovlev, D. L.; Sambor, E. G.

    2002-05-01

    Mechanisms and rates of laser-induced gas-phase reactions of vibrationally excited triplet ketones were studied after adding electron and hydrogen donors using time-resolved delayed fluorescence. The influence of various bimolecular competing processes on DF quenching was analyzed.

  4. Verification of a characterization method of the laser-induced selective activation based on industrial lasers

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; Tang, Peter T.

    2013-01-01

    In this article, laser-induced selective activation (LISA) for subsequent autocatalytic copper plating is performed by several types of industrial scale lasers, including a Nd:YAG laser, a UV laser, a fiber laser, a green laser, and a short pulsed laser. Based on analysis of all the laser-machine...

  5. Positron emission tomography of laser-induced interstitial hyperthermia in cerebral gliomas

    Science.gov (United States)

    Ulrich, Frank; Bettag, Martin; Langen, K. J.

    1991-05-01

    Up to the present 5 patients with cerebral gliomas (WHO II-III) were treated by stereotactic, laser-induced, interstitial thermal therapy (SLIITT). Parameters used in SLIITT were 3 watts as continuous wave over 5-10 minutes in single or multiple foci depending on the size of the tumor.

  6. Combined raman/laser-induced breakdown spectrometer: space and non-space applications

    NARCIS (Netherlands)

    Sandtke, M.; Laan, E.C.; Ahlers, B.

    2010-01-01

    TNO has developed the combination of two spectroscopic analysis methods in one instrument. Raman spectroscopy and Laser-induced Breakdown Spectroscopy (LIBS) were brought together for an instrument to be flown on the ExoMars mission from the European Space Agency (ESA) to investigate the Martian

  7. Laser induced fluorescence measurements of the mixing of fuel oil with air

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, A.; Bombach, R.; Hubschmid, W.; Kaeppeli, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    We report on measurements of the mixing of fuel oil with air at atmospheric pressure in an industrial premixed gas turbine burner. The concentration of the vaporized fuel oil was measured with laser induced fluorescence. We reason that the fuel oil concentration can be considered with good accuracy as proportional to the fluorescence intensity. (author) 6 fig., 3 refs.

  8. A Combined Mathematical-Physical Model of Laser-Induced Thermotherapy (LITT)

    DEFF Research Database (Denmark)

    Enevoldsen, Marie Sand; Skovgaard, Ove; Andersen, Peter E.

    2009-01-01

    Laser{induced thermo therapy (LITT) is an alternative, gentle therapy of cancer. In this work a new computa- tional model (3D space and time) of LITT is presented. Using an arbitrary small number (<20) of optical ¯bers, multiple low energy laser light sources are applied internal to an arbitrary ...

  9. Laser-induced down-conversion parameters of singly and doubly ...

    Indian Academy of Sciences (India)

    Singly and doubly doped ZnS phosphors have been synthesized using flux method. Laser-induced photoluminescence has been observed in ZnS-doped phosphors when these were excited by the pulsed UV N2 laser radiation. Due to down-conversion phenomenon, fast phosphorescence emission in the visible region is ...

  10. Choroidal Excavation in Eye with Normal Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Kazunobu Asao

    2014-05-01

    Full Text Available Purpose: To report the case of an eye with normal tension glaucoma and a choroidal excavation. Methods: This is an observational case report. Results: A 59-year-old woman with normal tension glaucoma had a choroidal excavation in the left eye. Her best-corrected visual acuity and intraocular pressure were within normal limits and had been stable for 5 years. Fundus examination showed a small white lesion inferior to the macula and a nerve fiber layer defect at the inferior edge of the optic disc. Humphrey Field Analyzer (HFA showed visual field defects corresponding to the nerve fiber layer defect with C30-2, and a central scotoma superior to the macula with C10-2. Optical coherence tomography (OCT showed a 150-µm deep choroidal excavation. Disruptions of the IS/OS line were detected only in the area inferior to the choroidal excavation. During the 5 months of follow-up, her best-corrected visual acuity remained at 1.0 and the IOP ranged from 12 to 14 mm Hg in the left eye. The fundus and OCT images did not deteriorate and the choroidal excavation did not enlarge. Conclusions: The disruption of the inner/outer segment (IS/OS line was detected only at the area surrounding the choroidal excavation. OCT examinations are useful in assessing the area of the residual IS/OS line, and HFA can be used to estimate the residual central visual field.

  11. Choroidal excavation in vogt-koyanagi-harada disease.

    Science.gov (United States)

    Hashida, Noriyasu; Fok, Andrew; Nishida, Kohji

    2014-05-01

    To report a case of choroidal excavation accompanied by Vogt-Koyanagi-Harada disease (VKH). A 54-year-old Japanese woman who was complaining of bilateral blurring of vision associated with headache underwent optical coherence tomography (OCT), fluorescein angiography, and indocyanine green angiography as well as a routine ophthalmological examination. Fundoscopy showed papilloedema and serous retinal detachment in both eyes. Fluorescein angiography detected bilateral multifocal leakage with pooling of dye in the subretinal space. Indocyanine green angiography showed patches of hyperfluorescence and hypofluorescent spots bilaterally. A diagnosis of VKH was reached soon afterwards. OCT of the left eye revealed the presence of a unilateral choroidal excavation under the fovea and subretinal fibrin over the site of the excavation. Treatment successfully resolved VKH symptoms with gradual resolution of subretinal fibrin and fluid; however, the choroidal excavation remained. This case is the first report of choroidal excavation associated with VKH. Our results suggest that choroidal excavation can be induced by choroidal inflammation caused by VKH.

  12. Choroidal excavation in eye with normal tension glaucoma.

    Science.gov (United States)

    Asao, Kazunobu; Morimoto, Takeshi; Nakada, Atsuko; Kawasaki, Yoshimi

    2014-05-01

    To report the case of an eye with normal tension glaucoma and a choroidal excavation. This is an observational case report. A 59-year-old woman with normal tension glaucoma had a choroidal excavation in the left eye. Her best-corrected visual acuity and intraocular pressure were within normal limits and had been stable for 5 years. Fundus examination showed a small white lesion inferior to the macula and a nerve fiber layer defect at the inferior edge of the optic disc. Humphrey Field Analyzer (HFA) showed visual field defects corresponding to the nerve fiber layer defect with C30-2, and a central scotoma superior to the macula with C10-2. Optical coherence tomography (OCT) showed a 150-µm deep choroidal excavation. Disruptions of the IS/OS line were detected only in the area inferior to the choroidal excavation. During the 5 months of follow-up, her best-corrected visual acuity remained at 1.0 and the IOP ranged from 12 to 14 mm Hg in the left eye. The fundus and OCT images did not deteriorate and the choroidal excavation did not enlarge. The disruption of the inner/outer segment (IS/OS) line was detected only at the area surrounding the choroidal excavation. OCT examinations are useful in assessing the area of the residual IS/OS line, and HFA can be used to estimate the residual central visual field.

  13. Nine orders of magnitude dynamic range: picomolar to millimolar concentration measurement in capillary electrophoresis with laser induced fluorescence detection employing cascaded avalanche photodiode photon counters.

    Science.gov (United States)

    Dada, Oluwatosin O; Essaka, David C; Hindsgaul, Ole; Palcic, Monica M; Prendergast, Jillian; Schnaar, Ronald L; Dovichi, Norman J

    2011-04-01

    The dynamic range of capillary electrophoresis analysis is ultimately limited by molecular shot noise at low concentrations and by concentration-induced band broadening at high concentrations. We report a system that approaches these fundamental limits. A laser-induced fluorescence detector is reported that employs a cascade of four fiber-optic beam splitters connected in series to generate a primary signal and four attenuated signals, each monitored by a single-photon counting avalanche photodiode. Appropriate scaling of the signals from the five photodiodes produces a linear optical calibration curve for 5-carboxyl-tetramethylrhodamine from the concentration detection limit of 1 pM to the upper limit of 1 mM. Mass detection limits are 120 yoctomoles (70 molecules) injected into the instrument. The very-wide dynamic range instrument was used to study the metabolic products of the fluorescently labeled glycosphingolipid tetramethylrhodamine labeled GM1 (GM1-TMR) produced by single cells isolated from the rat cerebellum.

  14. Outcomes of anti-vascular endothelial growth factor therapy in the management of choroidal neovascularization associated with choroidal osteoma.

    Science.gov (United States)

    Khan, Mohammed A; DeCroos, Francis C; Storey, Philip P; Shields, Jerry A; Garg, Sunir J; Shields, Carol L

    2014-09-01

    To investigate the efficacy of serial anti-vascular endothelial growth factor injections for choroidal neovascularization associated with choroidal osteoma. In this retrospective interventional case series, eyes with choroidal osteoma and associated choroidal neovascularization were treated with intravitreal ranibizumab or bevacizumab with or without photodynamic therapy consolidation. Resolution of subretinal fluid on optical coherence tomography and best-corrected visual acuity were assessed. Eight eyes in eight patients were treated with monthly intravitreal anti-vascular endothelial growth factor injections with or without photodynamic therapy. Resolution of subretinal fluid on optical coherence tomography was achieved in 7 of 8 eyes (87%) with a mean of 12.3 ± 12.6 injections (range, 1-40). Four eyes (50%) experienced at least 1 recurrence of exudation at a mean interval of 10 months (median, 7.5; range, 5-21 months), necessitating further therapy. The mean Snellen visual acuity improvement was 1 ± 4 lines (range, loss 3 to gain 7 lines) at a mean of 32-months follow-up. Serial anti-vascular endothelial growth factor therapy alone or with photodynamic therapy consolidation for choroidal neovascularization due to choroidal osteoma resulted in anatomical improvement and modest visual gain.

  15. Comparison of endostatin(endostarand avastin's inhibition effect on mice choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Jing Li

    2014-06-01

    Full Text Available AIM:To observe the inhibition effect of endostatin(endostaron mice choroidal neovascularization model(CNVand compare with the Avastin.METHODS: Using 532nm laser photocoagulation to establish a mouse model of CNV. We observed the formation of CNV by histopathological examination after 2wk later. Forty successful models of mice were randomly divided into control group(group 1, 10 rats, normal saline group(group 2, 10 rats, endostatin group(group 3, 10 ratsand avastin group(group 4, 10 rats. The drugs were injected into the mice' vitreous after photocoagulation 2wk later. Then 1wk later, we took the mice eyeballs to perform the HE and immunohistochemical staining to observe. The statistical analysis of ANOVA was done by SPSS 16.0 and the LSD-t test was used for multiple samples, taking PRESULTS: Two weeks later, HE histopathological examination was done, light microscope showed large amount of new vessels' formation, the positive rate for CNV was 72.8%. The blank control group compared with the normal saline group P>0.05, had no inhibitory effect on CNV; endostatin treated group compared with control group, PPt was performed on Avastin group and endostatin group, P(-overxAvastin =26.90,(-overxendostatin=29.13,(-overxAvastin(-overxendostatin, we can infer that endostar had lower inhibitory effect on mice CNV than Avastin.CONCLUSION: Laser-induced CNV animal models of colored mice C57BL/6J is of short time and high rate establishment and it is an ideal model for CNV study. Endostar has certain inhibitory effect on CNV, and it is likely to become one of the important drugs for CNV-related diseases in the future.

  16. Choroidal dendritic cells require activation to present antigen and resident choroidal macrophages potentiate this response.

    Science.gov (United States)

    Forrester, J V; Lumsden, L; Duncan, L; Dick, A D

    2005-03-01

    The uveal compartment of the eye contains extensive networks of resident macrophages and dendritic cells. These cells are now recognised to have a role in many ocular pathologies. The aim of this study was to isolate, characterise, and compare the function of ciliary body/choroid dendritic cells and macrophages from the normal eye. Explants of rat and human ciliary body/choroid were cultured in vitro for various periods of time and cells harvested either from the supernatant fluid or from enzyme digested and washed explants. The cells were then phenotyped by microscopy and flow cytometry, examined by video time lapse photomicroscopy, and analysed functionally in a series of immunoassays. Two main types of dendritic cell were identified: large veil-like MHC class II(mid) motile but relatively non-translocatory cells and small MHC class II(hi) motile and rapidly translocating cells. Tissue macrophages mainly remained associated with the explants in culture but gradually lost their resident tissue marker (ED2) and detached from the explants as clusters of low density, large, CR3 (ED7)(+) cells, some of which underwent apoptosis. Video time lapse studies showed dendritic cells constantly interacting with large single cells and cell clusters by traversing the interstices of the cell clusters. In functional studies, freshly isolated dendritic cells were poor presenters of antigen and required activation by short term culture for acquisition of antigen presenting function. In contrast, dendritic cell depleted choroidal cell preparations containing macrophages and other cells failed to present antigen even after short term culture but augmented the antigen presenting function of dendritic cells when tested in co-culture. At least two types of dendritic cells are present in the normal ciliary body/choroid layer of the eye. It is likely that these cells have different functions based on their motility and potential to migrate to secondary lymphoid tissue either during normal

  17. Idiopathic polypoidal choroidal vasculopathy in Thai patients with clinical and angiographic choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Bhoomibunchoo C

    2017-02-01

    Full Text Available Chavakij Bhoomibunchoo,1 Yosanan Yospaiboon,1 Somanus Thoongsuwan,2 Duangnate Rojanaporn,3 Nawat Watanachai,4 Pichai Jirarattanasopa,5 Nattapon Wongcumchang,6 Atchara Amphornphruet,7 Sritatath Vongkulsiri,8 Eakkachai Arayangkoon9 1Department of Ophthalmology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 2Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, 3Department of Ophthalmology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, 4Department of Ophthalmology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 5Department of Ophthalmology, Faculty of Medicine, Prince of Songkla University, Songkhla, 6Department of Ophthalmology, Faculty of Medicine, Thammasat University, Pathum Thani, 7Department of Ophthalmology, Rajavithi Hospital, Bangkok, 8Department of Ophthalmology, Phramongkutklao Hospital, Bangkok, 9Department of Ophthalmology, Mettapracharak Hospital, Nakhon Pathom, Thailand Objective: This study aimed to study the prevalence and characteristics of idiopathic polypoidal choroidal vasculopathy (IPCV in Thai patients with clinical and angiographic choroidal neovascularization (CNV.Patients and methods: A consecutive case study of 140 patients presenting with CNV was conducted in nine large referral eye centers throughout Thailand. The demographic data, fundus photographs, fundus fluorescein angiography and indocyanine green angiography of the patients were analyzed.Results: Of 129 patients with clinical and angiographic CNV, IPCV was diagnosed in 100 patients (77.52%, idiopathic CNVs in 16 patients (12.40% and age-related macular degeneration (AMD in 12 patients (9.30%. Of the 107 eyes with IPCV, 90 eyes (84.11% had both branching venous networks (BVNs and polypoidal lesions. Most IPCV patients (93% had unilateral involvement and were at a younger age than AMD patients. In all, 79 eyes (73.83% had lesions found in the macular area, 14 eyes (13.08% in the

  18. A pilot study to image the vascular network of small melanocytic choroidal tumors with speckle noise-free 1050-nm swept source optical coherence tomography (OCT choroidal angiography).

    Science.gov (United States)

    Maloca, Peter; Gyger, Cyrill; Hasler, Pascal W

    2016-06-01

    To visualize and measure the vascular network of melanocytic choroidal tumors with speckle noise-free swept source optical coherence tomography (SS-OCT choroidal angiography). Melanocytic choroidal tumors from 24 eyes were imaged with 1050-nm optical coherence tomography (Topcon DRI OCT-1 Atlantis). A semi-automated algorithm was developed to remove speckle noise and to extract and measure the volume of the choroidal vessels from the obtained OCT data. In all cases, analysis of the choroidal vessels could be performed with SS-OCT without the need for pupillary dilation. The proposed method allows speckle noise-free, structure-guided visualization and measurement of the larger choroidal vessels in three dimensions. The obtained data suggest that speckle noise-free OCT may be more effective at identifying choroidal structures than traditional OCT methods. The measured volume of the extracted choroidal vessels of Haller's layer and Sattler's layer in the examined tumorous eyes was on average 0.982463955 mm(3) /982463956 μm(3) (range of 0.209764406 mm(3) /209764405.9 μm(3)to 1.78105544 mm(3) /1781055440 μm(3)). Full thickness obstruction of the choroidal vasculature by the tumor was found in 18 cases (72 %). In seven cases (18 %), choroidal vessel architecture did not show pronounced morphological abnormalities (18 %). Speckle noise-free OCT may serve as a new illustrative imaging technology and enhance visualization of the choroidal vessels without the need for dye injection. OCT can be used to identify and evaluate the choroidal vessels of melanocytic choroidal tumors, and may represent a potentially useful tool for imaging and monitoring of choroidal nevi and melanoma.

  19. Choroidal metastasis from early rectal cancer: Case report and literature review

    Directory of Open Access Journals (Sweden)

    Mitsuyoshi Tei

    2014-01-01

    CONCLUSION: This is the first report of choroidal metastasis from early rectal cancer. We consider it important to enforce systemic chemotherapy in addition to radiotherapy for choroidal metastasis from colorectal cancer.

  20. Gamma Knife Radiosurgery for Choroidal Hemangioma

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yun Taek; Kang, Se Woong [Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Lee, Jung-Il, E-mail: jilee@skku.edu [Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2011-12-01

    Purpose: Patients with choroidal hemangioma (CH), a benign ocular hamartoma, frequently presents with visual disturbance as a result of exudative retinal detachment (RD), which originates in subretinal fluid accumulation. We report our experience using the Leksell Gamma Knife in the management of symptomatic CH. Methods and Materials: Seven patients with symptomatic CH (circumscribed form in 3 patients and diffuse form in 4) were treated with the Leksell Gamma Knife at our institution during a 7-year period. All patients presented with exudative RD involving the macula that resulted in severe visual deterioration. The prescription dose to the target margin was 10 Gy in all cases. The mean tumor volume receiving the prescription dose was 536 mm{sup 3} (range, 151-1,057). The clinical data were analyzed in a retrospective fashion after a mean follow-up of 34.4 months (range, 9-76). Results: The resolution of exudative RD was achieved within 6 months, and the visual acuity of the affected eye had improved at the latest follow-up examination (p = .018) in all patients. No recurrence of exudative RD occurred. Thinning of the CHs was observed in most patients; however, symptomatic radiation toxicity had not developed in any of the patients. Conclusion: Symptomatic CHs can be safely and effectively managed with Gamma Knife radiosurgery using a marginal dose of 10 Gy.

  1. Our Treatment Results of Circumscribed and Diffuse Choroidal Hemangiomas

    Directory of Open Access Journals (Sweden)

    Esra Savku

    2013-08-01

    Full Text Available Purpose: To discuss our treatment results of choroidal hemangiomas. Material and Method: The records of 39 cases of choroidal hemangioma followed up at our clinic between July 1999–October 2012 were reviewed retrospectively. Asymptomatic cases were followed up. Symptomatic cases with subretinal fluid and impaired vision received treatment. Results: Mean age of the 39 patients was 44 (12-80 years. Thirty-five of 39 cases had circumscribed choroidal hemangioma, and 4 cases had diffuse choroidal hemangioma. Sturge-Weber syndrome was present in 3 cases with diffuse choroidal hemangioma. Cases with circumscribed choroidal hemangioma and minimal subretinal fluid were treated with TTT in 11 cases, PDT in 12 cases, and PDT+TTT in 1 case. Cases with circumscribed choroidal hemangioma and excessive subretinal fluid were treated with Ru-106 plaque radiotherapy in 1 case, Ru-106 plaque radiotherapy+TTT in 1 case, EBRT in 3 cases, and TTT+EBRT in 1 case. One painful blind eye with neovascular glaucoma and complicated cataract was enucleated. Cases with diffuse choroidal hemangioma and excessive subretinal fluid were treated with Ru-106 plaque radiotherapy+TTT in 1 case and EBRT in 1 case. Ahmed glaucoma valve implantation and FAKO emulsification were applied to a case with neovascular glaucoma and complicated cataract. Complete resorption of subretinal fluid was achieved in 23 (72% of treated 32 cases. When mean initial tumor thickness was 2.6 mm (0.5-6, mean final tumor thickness was 1.4 mm (0-6. When mean initial visual acuity (LogMAR was 1.5 (0-3, mean final visual acuity was 1.1 (0-3. No recurrence was observed. Discussion: The amount of the subretinal fluid determines the method of treatment in circumscribed choroidal hemangioma. While TTT and PDT are effective treatment modalities for minimal subretinal fluid, plaque radiotherapy and EBRT are applied in cases with excessive subretinal fluid. Combination therapies may be necessary according to the

  2. [Late metastasis development in two cases of small choroidal melanoma].

    Science.gov (United States)

    Svetlošáková, Z; Malclès, A; Pommier, P; Krásnik, V; Grange, J D

    2013-08-01

    To present data pointing out that small tumour size might not be a sufficient predictor of good prognosis of choroidal melanoma and present a new promising therapy of hepatic metastasis. Retrospective, noncomparative case report of two patients with small choroidal melanoma. Two cases of small choroidal melanoma which developed metastases are described. Both patients underwent radiotherapy of the primary tumour. Metastases were treated by combined therapy in patient 1 while in patient 2 a new therapeutic modality of stereotactic radiotherapy, Cyberknife, was applied. Patient 1 died from metastatic spread 7,6 years after primary therapy despite a very good local tumour control. Patient 2 died 11,3 years after primary therapy due to intercurrent disease with a very good local eye findings and hepatic metastasis in regression. Choroidal melanoma of a small size can develop into metastatic disease even long time after satisfactory primary treatment. Further studies are required to assess the risk factors of metastatic spread in small uveal melanomas. Cyberknife stereotactic radiotherapy seems to be a promising therapeutic method of a solitary hepatic metastasis. Key words: choroidal melanoma, metastasis, prognostic factors, stereotactic radiotherapy.

  3. The Choroid Plexus in Healthy and Diseased Brain.

    Science.gov (United States)

    Kaur, Charanjit; Rathnasamy, Gurugirijha; Ling, Eng-Ang

    2016-03-01

    The choroid plexus is composed of epithelial cells resting on a basal lamina. These cells produce the cerebrospinal fluid (CSF), which has many functions including rendering mechanical support, providing a route for some nutrients, removing by-products of metabolism and synaptic activity, and playing a role in hormonal signaling. The choroid plexus synthesizes many growth factors, including insulin-like, fibroblast, and platelet-derived growth factors. The tight junctions located between the apical parts of the choroid plexus epithelial cells form the blood-CSF barrier (BCSFB), which is crucial for the homeostatic regulation of the brain microenvironment along with the blood-brain barrier (BBB). Morphological changes such as atrophy of the epithelial cells and thickening of the basement membrane suggest altered CSF production occurs in aging and in Alzheimer disease. In brain injuries and infections, leukocytes accumulate in the CSF by passing through the choroid plexus. In inflammatory CNS diseases (eg, multiple sclerosis), pathogenic autoreactive T lymphocytes may migrate through the BBB and BCSFB into the CNS. The development of therapeutic strategies to mitigate disruption of the BCSFB may be helpful to curtail the entry of inflammatory cells into the CSF and hence reduce inflammation, thereby overcoming choroid plexus dysfunction in senescence and in various diseases of the CNS. © 2016 American Association of Neuropathologists, Inc. All rights reserved.

  4. The acute effect of pseudoephedrine on choroidal thickness.

    Science.gov (United States)

    Ovet, G; Alpfidan, I; Sakarya, Y; Sakarya, R; Ozcimen, M; Göktaş, S; Erdoğan, E

    2016-01-01

    To investigate the acute effects of pseudoephedrine (PE) on choroidal thickness in healthy young patients. Fifty patients with nasal and sinus congestion who were prescribed 60 mg oral PE at the otolaryngology department were recruited for this study. The enhanced depth imaging (EDI) optic coherence tomography (OCT) (Spectralis OCT; Heidelberg Engineering, Heidelberg, Germany) choroidal thickness measurements were performed at baseline and 1, 3 and 6 hours at 7 points. The right eyes of 50 healthy subjects (22 women and 28 men) were included in this study. The mean choroidal thickness at fovea was 293.12 μm, 279.80 μm, 295.80 μm, and 294.52 μm at baseline, 1, 3 and 6 hours respectively. A significant reduction in choroidal thickness versus baseline was observed at all points at 1 hour. The choroidal thickness decreased 1 hour after oral administration of PE and returned to baseline thickness at 3 hours. We suppose that this transient decrease might be associated with vasoconstriction due to activation of sympathetic alpha adrenoceptors.

  5. Review of spectral domain enhanced depth imaging optical coherence tomography of tumors of the choroid

    Directory of Open Access Journals (Sweden)

    Carol L Shields

    2015-01-01

    Full Text Available Background: Spectral domain enhanced depth imaging optical coherence tomography (EDI-OCT can provide anatomic localization of intraocular tumors. Aims: The aim was to identify topographical and intrinsic patterns of choroidal tumors on EDI-OCT. Settings and Design: Retrospective review. Materials and Methods: Analysis of published reports and personal observations using office based EDI-OCT. Results: Using EDI-OCT, choroidal nevus displayed a smooth, dome-shaped topography with overlying retinal pigment epithelium alterations, drusen, and occasional subretinal cleft demonstrating photoreceptor loss. Small choroidal melanoma showed smooth, moderately dome-shaped topography, commonly with overlying shallow subretinal fluid that often depicted "shaggy" photoreceptors. Choroidal metastasis showed a minimally "lumpy, bumpy" surface topography and with overlying subretinal fluid and shaggy photoreceptors. Choroidal hemangioma showed a smooth, dome-shaped topography, with expansion of the affected small, medium, and large choroidal vessels. Choroidal lymphoma showed varying topography with increasing tumor thickness as "flat, rippled, or undulating (seasick" surface. Choroidal osteoma displayed a smooth undulating surface with visible intralesional horizontal lines suggestive of bone lamellae and occasional horizontal and vertical tubules with intralesional "spongy" flecks. Choroidal melanocytosis appeared as uniformly thickened choroid with increased stromal density surrounding the normal choroidal vascular structures. Conclusions: Enhanced depth imaging-OCT can depict characteristic patterns that are suggestive of various choroidal tumors.

  6. Experimental investigation on dynamic characteristics and strengthening mechanism of laser-induced cavitation bubbles.

    Science.gov (United States)

    Ren, X D; He, H; Tong, Y Q; Ren, Y P; Yuan, S Q; Liu, R; Zuo, C Y; Wu, K; Sui, S; Wang, D S

    2016-09-01

    The dynamic features of nanosecond laser-induced cavitation bubbles near the light alloy boundary were investigated with the high-speed photography. The shock-waves and the dynamic characteristics of the cavitation bubbles generated by the laser were detected using the hydrophone. The dynamic features and strengthening mechanism of cavitation bubbles were studied. The strengthening mechanisms of cavitation bubble were discussed when the relative distance parameter γ was within the range of 0.5-2.5. It showed that the strengthening mechanisms caused by liquid jet or shock-waves depended on γ much. The research results provided a new strengthening method based on laser-induced cavitation shotless peening (CSP). Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Ultraviolet laser-induced lateral photovoltaic response in anisotropic black shale

    Science.gov (United States)

    Miao, Xinyang; Zhu, Jing; Zhao, Kun; Yue, Wenzheng

    2017-12-01

    The anisotropy of shale has significant impact on oil and gas exploration and engineering. In this paper, a-248 nm ultraviolet laser was employed to assess the anisotropic lateral photovoltaic (LPV) response of shale. Anisotropic angle-depending voltage signals were observed with different peak amplitudes ( V p) and decay times. We employed exponential models to explain the charge carrier transport in horizontal and vertical directions. Dependences of the laser-induced LPV on the laser spot position were observed. Owing to the Dember effect and the layered structure of shale, V p shows an approximately linear dependence with the laser-irradiated position for the 0° shale sample but nonlinearity for the 45° and 90° ones. The results demonstrate that the laser-induced voltage method is very sensitive to the structure of materials, and thus has a great potential in oil and gas reservoir characterization.

  8. Effect of cylindrical cavity height on laser-induced breakdown spectroscopy with spatial confinement

    Science.gov (United States)

    Shao, Junfeng; Wang, Tingfeng; Guo, Jin; Chen, Anmin; Jin, Mingxing

    2017-02-01

    In this paper, we present a study on the spatial confinement effect of laser-induced plasma with a cylindrical cavity in laser-induced breakdown spectroscopy (LIBS). The emission intensity with the spatial confinement is dependent on the height of the confinement cavity. It is found that, by selecting the appropriate height of cylindrical cavity, the signal enhancement can be significantly increased. At the cylindrical cavity (diameter = 2 mm) with a height of 6 mm, the enhancement ratio has the maximum value (approximately 8.3), and the value of the relative standard deviation (RSD) (7.6%) is at a minimum, the repeatability of LIBS signal is best. The results indicate that the height of confinement cavity is very important for LIBS technique to reduce the limit of detection and improve the precision.

  9. Physical properties of hydrated tissue determined by surface interferometry of laser-induced thermoelastic deformation

    Science.gov (United States)

    Dark, Marta L.; Perelman, Lev T.; Itzkan, Irving; Schaffer, Jonathan L.; Feld, Michael S.

    2000-02-01

    Knee meniscus is a hydrated tissue; it is a fibrocartilage of the knee joint composed primarily of water. We present results of interferometric surface monitoring by which we measure physical properties of human knee meniscal cartilage. The physical response of biological tissue to a short laser pulse is primarily thermomechanical. When the pulse is shorter than characteristic times (thermal diffusion time and acoustic relaxation time) stresses build and propagate as acoustic waves in the tissue. The tissue responds to the laser-induced stress by thermoelastic expansion. Solving the thermoelastic wave equation numerically predicts the correct laser-induced expansion. By comparing theory with experimental data, we can obtain the longitudinal speed of sound, the effective optical penetration depth and the Grüneisen coefficient. This study yields information about the laser-tissue interaction and determines properties of the meniscus samples that could be used as diagnostic parameters.

  10. Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge

    Science.gov (United States)

    MacDonald, N. A.; Cappelli, M. A.; Hargus, W. A.

    2012-11-01

    A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s^' }[1/2]10 - 6p^' }[3/2]2 xenon atomic transition at λ = 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

  11. Planar laser-induced fluorescence fuel imaging during gas-turbine relight

    DEFF Research Database (Denmark)

    Read, Robert; Rogerson, J.W.; Hochgreb, S.

    2013-01-01

    This experimental study investigates the influence of fuel distribution on ignition outcome during high-altitude relight of a gas turbine. Planar laser-induced fluorescence is used to image fuel inside a lean direct-injection combustor under realistic conditions. A novel apparatus is developed...... to permit planar laser-induced fluorescence imaging, in which large quantities of poorly atomized fuel impinges on the internal surfaces of the combustor. Results reveal high variability in atomization quality. In the absence of flame, small droplets are confined to areas of recirculating flow, whereas......-induced fluorescence is a useful tool for the analysis of all stages of altitude relight. Copyright © 2013 by R. W. Read, J. W. Rogerson, and S. Hochgreb....

  12. An intelligent artificial throat with sound-sensing ability based on laser induced graphene

    Science.gov (United States)

    Tao, Lu-Qi; Tian, He; Liu, Ying; Ju, Zhen-Yi; Pang, Yu; Chen, Yuan-Quan; Wang, Dan-Yang; Tian, Xiang-Guang; Yan, Jun-Chao; Deng, Ning-Qin; Yang, Yi; Ren, Tian-Ling

    2017-02-01

    Traditional sound sources and sound detectors are usually independent and discrete in the human hearing range. To minimize the device size and integrate it with wearable electronics, there is an urgent requirement of realizing the functional integration of generating and detecting sound in a single device. Here we show an intelligent laser-induced graphene artificial throat, which can not only generate sound but also detect sound in a single device. More importantly, the intelligent artificial throat will significantly assist for the disabled, because the simple throat vibrations such as hum, cough and scream with different intensity or frequency from a mute person can be detected and converted into controllable sounds. Furthermore, the laser-induced graphene artificial throat has the advantage of one-step fabrication, high efficiency, excellent flexibility and low cost, and it will open practical applications in voice control, wearable electronics and many other areas.

  13. Using NBOHC fluorescence to predict multi-pulse laser-induced damage in fused silica

    Science.gov (United States)

    Beaudier, Alexandre; Wagner, Frank R.; Natoli, Jean-Yves

    2017-11-01

    We investigate the evolution of the fluorescence signal as function of repeated nanosecond laser pulses up to laser-induced damage in fused silica at 266 nm. We observed a maximum in the fluorescence spectrum at 664 nm linked to NBOHCs (Non-Bridging Oxygen Hole Centers). This peak increases with shot number for a fixed fluence until damage occurs. Thanks to the data from the in situ fluorescence measurements, we propose a new method to predict the occurrence of laser damage in high quality fused silica samples like Herasil©and Suprasil 1©. This new method allows to reduce drastically the time of test and the area under study that are required to record the reference data for damage occurrence. Furthermore we measured that the lifetime of the laser-induced modifications is about 2 h in Herasil.

  14. Crystallo-optic diagnostics method of the soft laser-induced effects in biological fluids

    Science.gov (United States)

    Skopinov, S. A.; Yakovleva, S. V.

    1991-05-01

    Presently, it is well known that individual cells"2 and higher organisms3'4 exhibit a marked response to soft laser irradiation in certain parts of the visible and near infrared spectral ranges. Broad clinical applications of laser therapy and slow progress in understanding of the physical, chemical and biological mechanisms of this phenomenon make the task to search new methods of objectivisation of laser-induces bioeffects very insistent. In this paper we give a short review of the methods of structural-optical diagnostics of the soft laser-induced effects in biofluids (blood and its fractions, saliva, juices, mucuses, exudations, etc.) and suggest their applications in experimental and clinical studies of the soft laser bioeffects.

  15. A Simplified Approach for Predicting Pulsed-Laser-Induced Carrier Generation in Semiconductor

    Science.gov (United States)

    Hales, Joel M.; Khachatrian, Ani; Buchner, Stephen; Roche, Nicolas J.-H.; Warner, Jeffrey; McMorrow, Dale

    2017-03-01

    Simplified analytic expressions are presented for calculating pulsed-laser induced charge generation in devices with collection volumes of any size. The expressions for charge generation by single-photon absorption for various limiting cases are applied to charge-collection measurements for a bulk Si photodiode, and single-event upsets in a 90-nm CMOS, silicon on insulator (SOI), static random-access memory (SRAM). Strong quantitative agreement between the simplified expressions, the full numerical calculations, and the experimental data serves to validate the analytical expressions. Furthermore, despite the complexity of determining charge deposited via two-photon absorption, the analytic expressions exhibit excellent agreement with full charge-generation simulations utilizing nonlinear-optical beam propagation software. These expressions therefore, represent a convenient and accurate method for estimating pulsed-laser induced charge generation in specified volumes, and are particularly relevant for two-photon absorption, which previously has required the use of complex numerical approaches.

  16. Hyperspectral laser-induced flourescence imaging for assessing internal quality of kiwi fruit

    Science.gov (United States)

    Liu, Muhua; Liao, Yifeng; Zhou, Xiaomei

    2008-03-01

    This paper describes an experimental study on non-destructive methods for predicting quality of kiwifruits using fluorescence imaging. The method is based on hyperspectral laser-induced fluorescence imaging in the region between 700 and 1110 nm, and estimates the kiwifruits quality in terms of internal sugar content and firmness. A station for acquiring hyperspectral laser-induced fluorescence imaging has been designed and carefully choosing each component. The fluorescence imaging acquired by the station has been pre-processed by selecting regions of interest (ROIs) of 50 100 × pixels. A line regressing prediction method estimates the quality of kiwifruit samples. The results obtained in classification show that the station and prediction model enables the correct discrimination of kiwifruits internal sugar content and firmness with a percentage of r= 98.5%, SEP=0.4 and r=99.9%, SEP=0.62.

  17. Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge.

    Science.gov (United States)

    MacDonald, N A; Cappelli, M A; Hargus, W A

    2012-11-01

    A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s(')[1/2](1)(0)-6p(')[3/2](2) xenon atomic transition at λ = 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

  18. Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, N. A.; Cappelli, M. A. [Stanford Plasma Physics Laboratory, Stanford University, Stanford, California 94305 (United States); Hargus, W. A. Jr. [Air Force Research Laboratory, Edwards AFB, California 93524 (United States)

    2012-11-15

    A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s{sup Prime }[1/2]{sub 1}{sup 0}-6p{sup Prime }[3/2]{sub 2} xenon atomic transition at {lambda}= 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

  19. An alternative approach for femtosecond laser induced black silicon in ambient air

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yuncan; Ren Hai [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xianning West Road 28, Xi' an 710049 (China); Si Jinhai, E-mail: jinhaisi@mail.xjtu.edu.cn [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xianning West Road 28, Xi' an 710049 (China); Sun Xuehui; Shi Haitao; Chen Tao; Chen Feng; Hou Xun [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xianning West Road 28, Xi' an 710049 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer An alternative approach for femtosecond laser induced black silicon in ambient air is proposed. Black-Right-Pointing-Pointer Energy dispersive X-ray spectroscopy analysis shows that incorporated oxygen is effectively eliminated via etching. Black-Right-Pointing-Pointer Absorption measurement shows that the optical absorption of the black silicon is enhanced. Black-Right-Pointing-Pointer The formation mechanism of black silicon and the enhancement mechanism of the optical absorption are discussed. - Abstract: An alternative approach for femtosecond laser induced black silicon in ambient air is proposed, in which, black silicon is fabricated on a tellurium coated silicon substrate via femtosecond laser irradiation in ambient air, and selectively etching with hydrofluoric acid is employed to remove the incorporated oxygen. Results of energy dispersive X-ray spectroscopy analysis and absorption measurement show that oxygen is effectively eliminated via etching, and the optical absorption of the black silicon is enhanced.

  20. Identification of inks and structural characterization of contemporary artistic prints by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oujja, M. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Vila, A. [Departament de Pintura, Conservacio-Restauracio, Facultat de Belles Arts, Universitat de Barcelona, Pau Gargallo 4, 08028 Barcelona (Spain); Rebollar, E. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Garcia, J.F. [Departament de Pintura, Conservacio-Restauracio, Facultat de Belles Arts, Universitat de Barcelona, Pau Gargallo 4, 08028 Barcelona (Spain); Castillejo, M. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain)]. E-mail: marta.castillejo@iqfr.csic.es

    2005-08-31

    Identification of the inks used in artistic prints and the order in which different ink layers have been applied on a paper substrate are important factors to complement the classical stylistic aspects for the authentication of this type of objects. Laser-induced breakdown spectroscopy (LIBS) is investigated to determine the chemical composition and structural distribution of the constituent materials of model prints made by applying one or two layers of several blue and black inks on an Arches paper substrate. By using suitable laser excitation conditions, identification of the inks was possible by virtue of emissions from key elements present in their composition. Analysis of successive spectra on the same spot allowed the identification of the order in which the inks were applied on the paper. The results show the potential of laser-induced breakdown spectroscopy for the chemical and structural characterization of artistic prints.

  1. Mechanisms of two-color laser-induced field-free molecular orientation.

    Science.gov (United States)

    Spanner, Michael; Patchkovskii, Serguei; Frumker, Eugene; Corkum, Paul

    2012-09-14

    Two mechanisms of two-color (ω+2ω) laser-induced field-free molecular orientation, based on the hyperpolarizability and ionization depletion, are explored and compared. The CO molecule is used as a computational example. While the hyperpolarizability mechanism generates small amounts of orientation at intensities below the ionization threshold, ionization depletion quickly becomes the dominant mechanism as soon as ionizing intensities are reached. Only the ionization mechanism leads to substantial orientation (e.g., on the order of ≳0.1). For intensities typical of laser-induced molecular alignment and orientation experiments, the two mechanisms lead to robust, characteristic timings of the field-free orientation wave-packet revivals relative to the alignment revivals and the revival time. The revival timings can be used to detect the active orientation mechanism experimentally.

  2. Quantitative Classification of Quartz by Laser Induced Breakdown Spectroscopy in Conjunction with Discriminant Function Analysis

    Directory of Open Access Journals (Sweden)

    A. Ali

    2016-01-01

    Full Text Available A responsive laser induced breakdown spectroscopic system was developed and improved for utilizing it as a sensor for the classification of quartz samples on the basis of trace elements present in the acquired samples. Laser induced breakdown spectroscopy (LIBS in conjunction with discriminant function analysis (DFA was applied for the classification of five different types of quartz samples. The quartz plasmas were produced at ambient pressure using Nd:YAG laser at fundamental harmonic mode (1064 nm. We optimized the detection system by finding the suitable delay time of the laser excitation. This is the first study, where the developed technique (LIBS+DFA was successfully employed to probe and confirm the elemental composition of quartz samples.

  3. Simultaneous laser-induced fluorescence and Rayleigh scattering measurements of structure in partially premixed flames

    Energy Technology Data Exchange (ETDEWEB)

    Heberle, N.H.; Smith, G.P.; Jeffries, J.B.; Crosley, D.R. [SRI International, Menlo Park, CA (United States). Materials Research Lab.; Dibble, R.W. [Combustion Analysis Laboratory, Department of Mechanical Engineering, University of California Berkeley, CA 94720 (United States)

    2000-11-01

    Laser-induced fluorescence and Rayleigh scattering measurements were made in well-stabilized, laminar partially premixed Bunsen-type methane/air flames. Simultaneous Rayleigh scattering (temperature) and laser-induced fluorescence (flame radical concentration) enable precise determination of the position of CH and OH radical structures in the gradient of the flame temperature. The OH and CH structures in the straight walls of the premixed inner flame cone are well described by models incorporating detailed flame chemistry and one-dimensional transport. Near the tip of the inner cone in regions of increased flame stretch, at richer stoichiometries of the premixed portion of the flames, and in flames perturbed by a metal insert, the measured structure of CH and OH deviates from this simple description. CH concentrations predicted by the model depend on flow rate, thus suggesting the importance of strain rate to prompt NO{sub x} formation in these flames. (orig.)

  4. Applicability of KrF excimer laser induced fluorescence in sooting high-pressure flames

    Energy Technology Data Exchange (ETDEWEB)

    Hildenbrandt, F.; Schulz, C.; Sick, V.; Jander, H.; Wagner, H.G.

    1999-07-01

    Laser-induced emissions obtained after excitation with a tunable KrF excimer laser at 248 nm were measured in well-defined sooting laminar high-pressure flames fueled with methane/air and ethylene/air up to 15 bar. A spectral analysis shows that Mie scattering, Raman scattering and laser-induced fluorescence (LIF) signals can be used for detailed flame studies under sooting high-pressure conditions. Mie scattering is correlated with soot, Raman signals can be used to measure spatially-resolved major species concentrations as well as temperatures. A LIF-scheme to measure NO was found to be applicable even under these conditions. The broadband fluorescence in the range from 270 to 290 nm, usually discarded as background, correlates well with the total concentration of polycyclic aromatic hydrocarbons (PAH) as measured via GC-MS methods. (orig.)

  5. Detection of toxic metals in waste water from dairy products plant using laser induced breakdown spectroscopy.

    Science.gov (United States)

    Hussain, T; Gondal, M A

    2008-06-01

    Laser Induced Breakdown Spectroscopy (LIBS) System was developed locally for determination of toxic metals in liquid samples and the system was tested for analysis of waste water collected from dairy products processing plant. The plasma was generated by focusing a pulsed Nd: YAG laser at 1064 nm on waste water samples. Optimal experimental conditions were evaluated for improving the sensitivity of our LIBS system through parametric dependence investigations. The Laser-Induced Breakdown Spectroscopy (LIBS) results were then compared with the results obtained using standard analytical technique such as Inductively Coupled Plasma Emission Spectroscopy (ICP). The evaluation of the potential and capabilities of LIBS as a rapid tool for liquid sample analysis are discussed in brief.

  6. Time-domain Brillouin scattering for the determination of laser-induced temperature gradients in liquids

    Science.gov (United States)

    Chaban, Ievgeniia; Shin, Hyun D.; Klieber, Christoph; Busselez, Rémi; Gusev, Vitalyi E.; Nelson, Keith A.; Pezeril, Thomas

    2017-07-01

    We present an optical technique based on ultrafast photoacoustics to determine the local temperature distribution profile in liquid samples in contact with a laser heated optical transducer. This ultrafast pump-probe experiment uses time-domain Brillouin scattering (TDBS) to locally determine the light scattering frequency shift. As the temperature influences the Brillouin scattering frequency, the TDBS signal probes the local laser-induced temperature distribution in the liquid. We demonstrate the relevance and the sensitivity of this technique for the measurement of the absolute laser-induced temperature gradient of a glass forming liquid prototype, glycerol, at different laser pump powers—i.e., different steady state background temperatures. Complementarily, our experiments illustrate how this TDBS technique can be applied to measure thermal diffusion in complex multilayer systems in contact with a surrounding liquid.

  7. Simultaneous laser induced breakdown spectroscopy and Pd-assisted methane decomposition at different pressures

    Energy Technology Data Exchange (ETDEWEB)

    Reyhani, A. [Phys. Dept., Faculty of Science, Imam Khomeini International University, Qazvin, 34149-16818 (Iran, Islamic Republic of); Mortazavi, S.Z. [Phys. Dept., Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Parvin, P., E-mail: parvin@aut.ac.ir [Phys. Dept., Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Mahmoudi, Z. [Phys. Dept., Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2012-08-15

    Methane decomposition is investigated during Pd-assisted laser induced plasma in the controlled chamber at various pressures using Q-switched Nd:YAG laser. Real time LIBS monitoring is applied to reveal the involved mechanisms during methane decomposition by inspecting the plasma parameters at mano-metric pressures of 1 to 10 mbar. The dependence of electron density and plasma temperature with pressure is also studied. It is shown that the plasma recreates higher hydrocarbons during the decomposition of methane. In addition, Fourier transform infrared spectroscopy, gas chromatography, scanning electron microscopy and transmission electron microscopy are applied to support the findings. - Highlights: Black-Right-Pointing-Pointer Simultaneous laser induced breakdown spectroscopy Black-Right-Pointing-Pointer Pd-assisted methane decomposition Black-Right-Pointing-Pointer Nanosecond pulsed laser decomposition of methane Black-Right-Pointing-Pointer Generation of higher hydrocarbon Black-Right-Pointing-Pointer Dependence of electron density and temperature of induced plasma with pressure.

  8. Analysis of laser-induced fluorescence spectra of in vitro plant tissue cultures

    Science.gov (United States)

    Muñoz-Muñoz, Ana Celia; Gutiérrez-Pulido, Humberto; Rodríguez-Domínguez, José Manuel; Gutiérrez-Mora, Antonia; Rodríguez-Garay, Benjamín; Cervantes-Martínez, Jesús

    2007-04-01

    We demonstrate the effectiveness of laser-induced fluorescence (LIF) for monitoring the development and stress detection of in vitro tissue cultures in a nondestructive and noninvasive way. The changes in LIF spectra caused by the induction of organogenesis, the increase of the F690/F740 ratio as a result of the stress originated in the organogenic explants due to shoot emergence, and the relationship between fluorescence spectra and shoot development were detected by LIF through closed containers of Saintpaulia ionantha.

  9. Experimental evidence of new tetragonal polymorphs of silicon formed through ultrafast laser-induced confined microexplosion

    OpenAIRE

    Rapp, L.; Haberl, B.; Pickard, C. J.; J.E. Bradby; Gamaly, E. G.; Williams, J.S.; Rode, A. V.

    2015-01-01

    Ordinary materials can transform into novel phases at extraordinary high pressure and temperature. The recently developed method of ultrashort laser-induced confined microexplosions initiates a non-equilibrium disordered plasma state. Ultra-high quenching rates overcome kinetic barriers to the formation of new metastable phases, which are preserved in the surrounding pristine crystal for subsequent exploitation. Here we demonstrate that confined microexplosions in silicon produce several meta...

  10. Laser Induced C60 Cage Opening Studied by Semiclassical Dynamics Simulation

    Directory of Open Access Journals (Sweden)

    Yusheng Dou

    2011-01-01

    Full Text Available Laser induced opening of the C60 cage is studied by a semiclassical electron-radiation-ion dynamics technique. The simulation results indicate that the C60 cage is abruptly opened immediately after laser excitation. The opening of the C60 cage induces a quick increase in kinetic energy and a sharp decrease in electronic energy, suggesting that the breaking of the C60 cage efficiently heats up the cluster and enhances the thermal fragmentation of C60 fullerene.

  11. Field Observations with Laser-Induced Fluorescence Transient (LIFT) Method in Barley and Sugar Beet

    OpenAIRE

    Anna R. Raesch; Onno Muller; Roland Pieruschka; Uwe Rascher

    2014-01-01

    The laser-induced fluorescence transient (LIFT) method is a non-invasive remote sensing technique for measurement of photosynthetic performance of plants under laboratory and field conditions. We report here a long-term comparative study to monitor the performance of different cultivars of barley and sugar beet during the growth season of these crops. The LIFT measurements provided useful results about photosynthetic light use efficiency on selected leaves in the canopy of the studied crops. ...

  12. Determining spatial sodium distribution in fresh and aged bread using laser-induced breakdown spectroscopy

    NARCIS (Netherlands)

    Scholtes-Timmerman, M.; Heddes, C.; Noort, M.W.J.; Veen, S. van

    2013-01-01

    A fast and easy-to-use method using laser-induced breakdown spectroscopy (LIBS) was set up to determine Na (sodium) distribution in baked bread. Standard bread was made using a standard recipe and the amount of salt added was 0, 0.5, 1, 2, 4, 10, 15 and 20g corresponding to 0, 0.25, 0.5, 1.0, 2.0,

  13. Ultrasound measurements of cavitation bubble radius for femtosecond laser-induced breakdown in water.

    Science.gov (United States)

    Aglyamov, Salavat R; Karpiouk, Andrei B; Bourgeois, Frederic; Ben-Yakar, Adela; Emelianov, Stanislav Y

    2008-06-15

    A recently developed ultrasound technique is evaluated by measuring the behavior of a cavitation bubble that is induced in water by a femtosecond laser pulse. The passive acoustic emission during optical breakdown is used to estimate the location of the cavitation bubble's origin. In turn, the position of the bubble wall is defined based on the active ultrasonic pulse-echo signal. The results suggest that the developed ultrasound technique can be used for quantitative measurements of femtosecond laser-induced microbubbles.

  14. Laser-induced corneal cross-linking upon photorefractive ablation with riboflavin

    OpenAIRE

    Kornilovskiy IM; Kasimov EM; Sultanova AI; Burtsev AA

    2016-01-01

    Igor M Kornilovskiy,1 Elmar M Kasimov,2 Ayten I Sultanova,2 Alexander A Burtsev1 1Department of Eye Diseases, Federal State Budgetary Institution “National Pirogov Medical Surgical Centre”, Ministry of Health, Moscow, Russia; 2Department of Eye Diseases, Zarifa Aliyeva National Ophthalmology Center, Ministry of Health, Baku, Azerbaijan Aim: To estimate the biomechanical effect of the laser-induced cross-linking resulting from photorefractive ablation of the cornea with r...

  15. Clinical diagnosis of fissure caries with conventional and laser-induced fluorescence techniques

    OpenAIRE

    Chu, CH; Lo, ECM; You, DSH

    2010-01-01

    We studied the in vivo validity of dentinal fissure caries diagnosis by visual examination, bitewing radiography, and use of a laser-induced fluorescence device (DIAGNOdent). A total of 144 and second molars with macroscopically intact occlusal surfaces in 41 Chinese young adults were examined visually, by bitewing radiography, and by DIAGNOdent. Visual examination after pit and fissure opening was used as the reference standard. The sensitivity and specificity of detecting caries that had ex...

  16. Applications of Laser-Induced Breakdown Spectroscopy (LIBS) in Molten Metal Processing

    Science.gov (United States)

    Hudson, Shaymus W.; Craparo, Joseph; De Saro, Robert; Apelian, Diran

    2017-10-01

    In order for metals to meet the demand for critical applications in the automotive, aerospace, and defense industries, tight control over the composition and cleanliness of the metal must be achieved. The use of laser-induced breakdown spectroscopy (LIBS) for applications in metal processing has generated significant interest for its ability to perform quick analyses in situ. The fundamentals of LIBS, current techniques for deployment on molten metal, demonstrated capabilities, and possible avenues for development are reviewed and discussed.

  17. Laser-induced transformation of GaS and GaSe nanosheets to ...

    Indian Academy of Sciences (India)

    Administrator

    Laser-induced transformation of GaS and GaSe nanosheets to onion structures. 1385. Figure 3. FESEM images of few-layer GaS as a function of number of laser pulses: (a) as-prepared,. (b) after 5 layer pulses, (c) after 20 layer pulses and (d) 50 laser pulses. In figure 5(a), we show the TEM image of dewetted.

  18. Successful treatment of laser induced hypopigmentation with narrowband ultraviolet B targeted phototherapy

    Directory of Open Access Journals (Sweden)

    Venkataram Mysore

    2013-01-01

    Full Text Available Q-switched 1064 nm neodymium-doped yttrium aluminium garnet (Qs 1064 nm Nd: YAG laser plays an important role in the treatment of pigmentary skin disorders, including tattoos. Although it has high efficacy and safety, adverse effect like hypopigmentation may occur causing anxiety to patients. We present a case report of Qs 1064 nm Nd: YAG laser induced hypopigmentation which was successfully treated with ultraviolet B targeted phototherapy, with rapid and satisfactory re-pigmentation.

  19. Laser-induced rotation of iodine molecules in He-nanodroplets

    DEFF Research Database (Denmark)

    Shepperson, Benjamin; Søndergaard, Anders A.; Christiansen, Lars

    2017-01-01

    Rotation of molecules embedded in He nanodroplets is explored by a combination of fs laser-induced alignment experiments and angulon quasiparticle theory. We demonstrate that at low fluence of the fs alignment pulse, the molecule and its solvation shell can be set into coherent collective rotation...... shell. Our results open novel opportunities for studying non-equilibrium solute-solvent dynamics and quantum thermalization....

  20. Serum Protein Profile Study of Clinical Samples Using High Performance Liquid Chromatography-Laser Induced Fluorescence

    DEFF Research Database (Denmark)

    Karemore, Gopal Raghunath; Ukendt, Sujatha; Rai, Lavanya

    2009-01-01

    The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested...... for establishing the ability of HPLC-LIF protein profiling technique for discrimination, using hard clustering and Fuzzy clustering methods. The clustering algorithms have quite successfully classified the profiles as belonging to normal, cancer of cervix, and oral cancer conditions....

  1. Laser-induced fluorescence of jet-cooled 7-diethylamino-4-trifluoromethyl coumarin

    Science.gov (United States)

    Taylor, A. G.; Bouwman, W. G.; Jones, A. C.; Guo, C.; Phillips, D.

    1988-03-01

    Laser-induced fluorescence excitation and emission spectra of 7-diethylamino-4-trifluoromethyl coumarin (C152A) cooled in a supersonic expansion of helium are reported. The lowest observed excitation band is assigned as the vibrationless. 0 00 transition in disagreement with a previous assignment. The present assignment is consistent with a Franck-Condon simulation of the spectral intensities. No evidence was found for the formation of a twisted intramolecular charge transfer (TICT) state by the isolated jet-cooled molecule.

  2. Laser Induced Fluorescence (LIF) Nondestructive Evaluation of Incipient Heat Damage in Polymer Matrix Composites, A2476

    Science.gov (United States)

    2017-02-15

    02-2017 2. REPORT TYPE Final 3. DATES COVERED (From - To) Oct 2011 - Jul 2016 4. TITLE AND SUBTITLE Laser Induced Fluorescence (LIF...Instances of mechanical strength degradation from incipient heat damage in aircraft PMCs exceeding 60% have been reported (Fisher et al., 1995). Currently...forms of exposure. Bowie’s master’s thesis (2017) includes a review of the scientific and engineering literature on incipient heat damage in PMCs

  3. Effect of ambient gas pressure and nature on the temporal evolution of aluminum laser-induced plasmas

    National Research Council Canada - National Science Library

    Dawood, M. S; Margot, Joëlle

    2014-01-01

    Time-resolved analysis of emission spectra, electron densities and excitation temperatures of Aluminum laser induced plasmas produced in argon, nitrogen and helium at different pressures have been studied experimentally...

  4. Laser-induced chemistry: an advanced tool for micro structuring, synthesis, and modification of materials

    Science.gov (United States)

    Metev, Simeon; Stephen, Andreas; Schwarz, Joerg; Wochnowski, Carsten

    2004-04-01

    Laser-induced technological chemical processes can significantly contribute to the development of new methods for micro treatment of materials and hence to the broadening of the application spectrum of laser microtechnology. In this paper three typical laser-activated chemical technological methods in liquids, gases and solids and their possible applications are presented and discussed: (1) Laser-induced liquid-phase jet-chemical etching of metals. In this method, laser radiation which is guided from a coaxially expanding liquid jet-stream initiates locally on a metal surface a thermochemical etching reaction, which leads to a selective material removal at high resolution (thermochemical CVD processes taking place in a photon-initiated stationary plasma maintained in the electromagnetic optical field of a high-power cw-CO2 laser radiation. This method allows synthesis of thin-film coatings in the open-air atmosphere without using vacuum or reaction chamber; (3) Laser-induced photochemical modification of the optical properties of polymers. This method is based on the local controllable change of the polymer structure leading to modification of the refractive index in the treated area. By numerous independently adjustable laser radiation parameters, for instance wavelength and irradiation dose, the modification process can be controllably driven in order to generate desired functional properties.

  5. [Study of self-absorption effect on laser-induced metal plasma].

    Science.gov (United States)

    Chen, Jin-Zhong; Ma, Rui-Ling; Wang, Jing; Li, Xu; Su, Hong-Xin

    2014-09-01

    In order to reduce the effect of the spectral line self-absorption on the analysis result in the laser induced plasma and enhance the qualities of spectrum, the spectral information was recorded by the spectral analysis system consisting of a modular multifunctional grating spectrometer and a CCD detector etc., and the electron temperature and electron density of the plasma were measured with the spectroscopic methods. A plane mirror device was used to constraint the laser plasma, and a reasonable explanation was got through comparing the linear evolution under different experimental conditions and measuring the temperature, electronic density and sample evaporation. The result shows that when an appropriate plane mirror device was used to constraint the laser plasma, the axial temperature of the plasma increased and the radial distribution of the plasma becomes uniform; the electron density increased dramatically; however, obviously sample evaporation decreased, which may be the reasons for being able to effectively reduce the level of self-absorption spectral lines. Therefore, the plane mirror device could reduce the self-absorption effect in the laser-induced plasma. This makes it possible to choose a sensitive line that acts as analysis line in the quantitative analysis of the major elements. In other words, this promotes the measurement precision in the laser-induced break-down spectroscopy.

  6. Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

    Directory of Open Access Journals (Sweden)

    Christian G. Parigger

    2010-01-01

    Full Text Available Transient laser plasma is generated in laser-induced optical breakdown (LIOB. Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and 1 μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Hönl-London factors.

  7. Laser-induced damage threshold of camera sensors and micro-optoelectromechanical systems

    Science.gov (United States)

    Schwarz, Bastian; Ritt, Gunnar; Koerber, Michael; Eberle, Bernd

    2017-03-01

    The continuous development of laser systems toward more compact and efficient devices constitutes an increasing threat to electro-optical imaging sensors, such as complementary metal-oxide-semiconductors (CMOS) and charge-coupled devices. These types of electronic sensors are used in day-to-day life but also in military or civil security applications. In camera systems dedicated to specific tasks, micro-optoelectromechanical systems, such as a digital micromirror device (DMD), are part of the optical setup. In such systems, the DMD can be located at an intermediate focal plane of the optics and it is also susceptible to laser damage. The goal of our work is to enhance the knowledge of damaging effects on such devices exposed to laser light. The experimental setup for the investigation of laser-induced damage is described in detail. As laser sources, both pulsed lasers and continuous-wave (CW)-lasers are used. The laser-induced damage threshold is determined by the single-shot method by increasing the pulse energy from pulse to pulse or in the case of CW-lasers, by increasing the laser power. Furthermore, we investigate the morphology of laser-induced damage patterns and the dependence of the number of destructive device elements on the laser pulse energy or laser power. In addition to the destruction of single pixels, we observe aftereffects, such as persistent dead columns or rows of pixels in the sensor image.

  8. Laser-induced damage threshold of camera sensors and micro-opto-electro-mechanical systems

    Science.gov (United States)

    Schwarz, Bastian; Ritt, Gunnar; Körber, Michael; Eberle, Bernd

    2016-10-01

    The continuous development of laser systems towards more compact and efficient devices constitutes an increasing threat to electro-optical imaging sensors such as complementary metal-oxide-semiconductors (CMOS) and charge-coupled devices (CCD). These types of electronic sensors are used in day-to-day life but also in military or civil security applications. In camera systems dedicated to specific tasks, also micro-opto-electro-mechanical systems (MOEMS) like a digital micromirror device (DMD) are part of the optical setup. In such systems, the DMD can be located at an intermediate focal plane of the optics and it is also susceptible to laser damage. The goal of our work is to enhance the knowledge of damaging effects on such devices exposed to laser light. The experimental setup for the investigation of laser-induced damage is described in detail. As laser sources both pulsed lasers and continuous-wave (CW) lasers are used. The laser-induced damage threshold (LIDT) is determined by the single-shot method by increasing the pulse energy from pulse to pulse or in the case of CW-lasers, by increasing the laser power. Furthermore, we investigate the morphology of laser-induced damage patterns and the dependence of the number of destructed device elements on the laser pulse energy or laser power. In addition to the destruction of single pixels, we observe aftereffects like persisting dead columns or rows of pixels in the sensor image.

  9. Sensitive elemental detection using microwave-assisted laser-induced breakdown imaging

    Science.gov (United States)

    Iqbal, Adeel; Sun, Zhiwei; Wall, Matthew; Alwahabi, Zeyad T.

    2017-10-01

    This study reports a sensitive spectroscopic method for quantitative elemental detection by manipulating the temporal and spatial parameters of laser-induced plasma. The method was tested for indium detection in solid samples, in which laser ablation was used to generate a tiny plasma. The lifetime of the laser-induced plasma can be extended to hundreds of microseconds using microwave injection to remobilize the electrons. In this novel method, temporal integrated signal of indium emission was significantly enhanced. Meanwhile, the projected detectable area of the excited indium atoms was also significantly improved using an interference-, instead of diffraction-, based technique, achieved by directly imaging microwave-enhanced plasma through a novel narrow-bandpass filter, exactly centered at the indium emission line. Quantitative laser-induce breakdown spectroscopy was also recorded simultaneously with the new imaging method. The intensities recorded from both methods exhibit very good mutual linear relationship. The detection intensity was improved to 14-folds because of the combined improvements in the plasma lifetime and the area of detection.

  10. Polarization-dependent single-beam laser-induced grating-like effects on titanium films

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Lopez, Santiago [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico)], E-mail: camachol@cicese.mx; Evans, Rodger [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico); Escobar-Alarcon, Luis [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico DF 11801 (Mexico); Camacho-Lopez, Miguel A. [Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan s/n, esq. Jesus Carranza, Toluca, Estado de Mexico 50120 (Mexico); Camacho-Lopez, Marco A. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Tollocan s/n, esq. Paseo Colon, Toluca, Estado de Mexico, 50110 (Mexico)

    2008-12-30

    In this paper we present results on polarization-dependent laser-induced effects on titanium (Ti) thin films. We irradiated the titanium films, in ambient air, using a nanosecond Nd:YAG laser (532 nm, 9 ns pulse duration, 10 Hz). Using a series of pulses of fluence well below the ablation threshold, it was possible to form grating-like structures, whose grooves run parallel to the linear polarization of the incident beam. No grating-like structures were obtained when circularly polarized light was used. Our results revealed the remarkable formation of tiny (100 nm and even smaller diameter) craters, which self-arrange quasi-periodically along the ridges (never on the valleys) of the grating-like structure. Optical and scanning electron microscopy were used to study the laser-induced changes on the surface of the titanium films. Micro-Raman spectroscopy was used to analyze the irradiated areas on the titanium films. The Raman analysis demonstrated that the grooves in the grating-like structure, build up from the laser-induced oxidation of titanium. This is the first time, to the best of our knowledge, that periodic surface structures are reported to be induced below the ablation threshold regime, with the grooves made of crystalline metal oxide, in this case TiO{sub 2} in the well-known Rutile phase. The laser irradiated areas on the film acquired selective (upon recording polarization) holographic reflectance.

  11. SELF-INFLICTED LASER HANDHELD LASER-INDUCED MACULOPATHY: A NOVEL OCULAR MANIFESTATION OF FACTITIOUS DISORDER.

    Science.gov (United States)

    Rabiolo, Alessandro; Sacconi, Riccardo; Giuffrè, Chiara; Corbelli, Eleonora; Carnevali, Adriano; Querques, Lea; Sarraf, David; Freund, K Bailey; Sadda, SriniVas; Bandello, Francesco; Querques, Giuseppe

    2017-09-19

    To report a case of factitious self-inflicted handheld laser-induced maculopathy. A 29-year-old man presented to our clinic complaining of a step-wise progressive loss of vision that abruptly began in his left eye but then became bilateral. He underwent comprehensive ocular examination, including visual acuity testing, biomicroscopic, dilated funduscopic examination, structural optical coherence tomography, en face structural optical coherence tomography, optical coherence tomography angiography, fundus autofluorescence, fluorescein angiography, and indocyanine green angiography. Visual acuity was 20/200 in both eyes. Although the multimodal imaging was highly consistent with handheld laser-induced maculopathy, the patient continued to deny this behavior. Self-inflicted handheld laser-induced maculopathy may be a novel manifestation of factitious disorder. Clinical suspicion for this should remain high in the presence of the signature multimodal retinal findings despite denial by the patient. This category of patients could benefit from psychiatric referral, to prevent further ocular or extra-ocular self-injury.

  12. A combined laser-induced breakdown and Raman spectroscopy Echelle system for elemental and molecular microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Hoehse, Marek [BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter Str. 11, D-12489 Berlin (Germany); Mory, David [LTB Lasertechnik Berlin, Rudower Chaussee 29, 12489 Berlin (Germany); Florek, Stefan [ISAS - Institute for Analytical Science, Albert-Einstein-Str. 9, D-12489 Berlin (Germany); Weritz, Friederike [BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter Str. 11, D-12489 Berlin (Germany); Gornushkin, Igor, E-mail: igor.gornushkin@bam.d [BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter Str. 11, D-12489 Berlin (Germany); Panne, Ulrich [BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter Str. 11, D-12489 Berlin (Germany); Humboldt Universitaet zu Berlin, Chemistry Department, Brook-Taylor-Strasse 2, D-12489 Berlin (Germany)

    2009-11-15

    Raman and laser-induced breakdown spectroscopy is integrated into a single system for molecular and elemental microanalyses. Both analyses are performed on the same approx 0.002 mm{sup 2} sample spot allowing the assessment of sample heterogeneity on a micrometric scale through mapping and scanning. The core of the spectrometer system is a novel high resolution dual arm Echelle spectrograph utilized for both techniques. In contrast to scanning Raman spectroscopy systems, the Echelle-Raman spectrograph provides a high resolution spectrum in a broad spectral range of 200-6000 cm{sup -1} without moving the dispersive element. The system displays comparable or better sensitivity and spectral resolution in comparison to a state-of-the-art scanning Raman microscope and allows short analysis times for both Raman and laser induced breakdown spectroscopy. The laser-induced breakdown spectroscopy performance of the system is characterized by ppm detection limits, high spectral resolving power (15,000), and broad spectral range (290-945 nm). The capability of the system is demonstrated with the mapping of heterogeneous mineral samples and layer by layer analysis of pigments revealing the advantages of combining the techniques in a single unified set-up.

  13. Spatial variability of oceanic phycoerythrin spectral types derived from airborne laser-induced fluorescence emissions

    Science.gov (United States)

    Hoge, Frank E.; Wright, C. Wayne; Kana, Todd M.; Swift, Robert N.; Yungel, James K.

    1998-07-01

    We report spatial variability of oceanic phycoerythrin spectral types detected by means of a blue spectral shift in airborne laser-induced fluorescence emission. The blue shift of the phycoerythrobilin fluorescence is known from laboratory studies to be induced by phycourobilin chromophore substitution at phycoerythrobilin chromophore sites in some strains of phycoerythrin-containing marine cyanobacteria. The airborne 532-nm laser-induced phycoerythrin fluorescence of the upper oceanic volume showed distinct segregation of cyanobacterial chromophore types in a flight transect from coastal water to the Sargasso Sea in the western North Atlantic. High phycourobilin levels were restricted to the oceanic (oligotrophic) end of the flight transect, in agreement with historical ship findings. These remotely observed phycoerythrin spectral fluorescence shifts have the potential to permit rapid, wide-area studies of the spatial variability of spectrally distinct cyanobacteria, especially across interfacial regions of coastal and oceanic water masses. Airborne laser-induced phytoplankton spectral fluorescence observations also further the development of satellite algorithms for passive detection of phytoplankton pigments. Optical modifications to the NASA Airborne Oceanographic Lidar are briefly described that permitted observation of the fluorescence spectral shifts.

  14. Lycopene mitigates β-amyloid induced inflammatory response and inhibits NF-κB signaling at the choroid plexus in early stages of Alzheimer's disease rats.

    Science.gov (United States)

    Liu, Chong-Bin; Wang, Rui; Yi, Yan-Feng; Gao, Zhen; Chen, Yi-Zhu

    2017-11-28

    The choroid plexus is able to modulate the cognitive function, through changes in the neuroinflammatory response and in brain immune surveillance. However, whether lycopene is involved in inflammatory responses at the choroid plexus in the early stages of Alzheimer's disease, and its molecular underpinnings are elusive. In this rat study, lycopene was used to investigate its protective effects on inflammation caused by β-amyloid. We characterized the learning and memory abilities, cytokine profiles of circulating TNF-α, IL-1β and IL-6β in the serum and the expressions of Toll like receptor 4 and nuclear factor-κB p65 mRNA and protein at the choroid plexus. The results showed that functional deficits of learning and memory in lycopene treatment groups were significantly improved compared to the control group without lycopene treatment in water maze test. The levels of serum TNF-α, IL-1β and IL-6β were significantly increased, and the expressions of TLR4 and NF-κB p65 mRNA and protein at the choroid plexus were up-regulated, indicating inflammation response was initiated following administration of Aβ1-42. After intragastric pretreatment with lycopene, inflammatory cytokines were significantly reduced and lycopene also reversed the Aβ1-42 induced up-regulation of TLR4 and NF-κB p65 mRNA and protein expressions at the choroid plexus. These results provided a novel evidence that lycopene significantly improved cognitive deficits and were accompanied by the attenuation of inflammatory injury via blocking the activation of NF-κB p65 and TLR4 expressions and production of cytokines, thereby endorsing its usefulness for diminishing β-amyloid deposition in the hippocampus tissues. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Engorgement of vortex vein and polypoidal choroidal vasculopathy.

    Science.gov (United States)

    Chung, Song Ee; Kang, Se Woong; Kim, Jae Hui; Kim, Yun Taek; Park, Do Young

    2013-04-01

    The purpose of this study was to identify a correlation between engorgement of the vortex vein and the development of polypoidal choroidal vasculopathy (PCV). Engorgement of the vortex vein was evaluated by masked observers using a montage of indocyanine green angiography images. Sixty-three eyes with PCV, 27 uninvolved fellow eyes with PCV, and 30 eyes of age-matched control subjects were included. The incidence and distribution pattern of engorgement were evaluated. Thirty-three eyes (52.4%) of PCV evidenced engorgement of the vortex vein, whereas such engorgement was detected in only 7 of the 30 eyes (30.4%) of the control subjects (P = 0.016). Among 27 fellow eyes with PCV, it was detected in 11 (40.7%) (P = 0.706 vs. control eyes). In all groups, it was most frequently detected at the inferior temporal quadrant. In eyes with PCV, mean (±standard deviation) choroidal thickness of the eyes evidencing vortex vein engorgement was 338.1 ± 131.3 μm and the thickness of those not evidencing vortex vein engorgement was 275.1 ± 107.7 μm. When the choroidal thickness increased to 10 μm in the eyes with PCV, the odds of detecting the engorgement was multiplied by a factor of 1.05 (P = 0.042). The incidence of the engorgement of vortex vein was correlated with the presence of choroidal vascular hyperpermeability (P = 0.009). This study demonstrates that engorgement of the vortex vein was observed more frequently in the eyes with PCV. Such a finding was associated with choroidal thickening and choroidal vascular hyperpermeability. These indicate that the engorgement of the vortex vein might be involved in the pathogenic mechanisms of PCV.

  16. Development of the choroid plexus and blood-CSF barrier

    Science.gov (United States)

    Liddelow, Shane A.

    2015-01-01

    Well-known as one of the main sources of cerebrospinal fluid (CSF), the choroid plexuses have been, and still remain, a relatively understudied tissue in neuroscience. The choroid plexus and CSF (along with the blood-brain barrier proper) are recognized to provide a robust protective effort for the brain: a physical barrier to impede entrance of toxic metabolites to the brain; a “biochemical” barrier that facilitates removal of moieties that circumvent this physical barrier; and buoyant physical protection by CSF itself. In addition, the choroid plexus-CSF system has been shown to be integral for normal brain development, central nervous system (CNS) homeostasis, and repair after disease and trauma. It has been suggested to provide a stem-cell like repository for neuronal and astrocyte glial cell progenitors. By far, the most widely recognized choroid plexus role is as the site of the blood-CSF barrier, controller of the internal CNS microenvironment. Mechanisms involved combine structural diffusion restraint from tight junctions between plexus epithelial cells (physical barrier) and specific exchange mechanisms across the interface (enzymatic barrier). The current hypothesis states that early in development this interface is functional and more specific than in the adult, with differences historically termed as “immaturity” actually correctly reflecting developmental specialization. The advanced knowledge of the choroid plexus-CSF system proves itself imperative to understand a range of neurological diseases, from those caused by plexus or CSF drainage dysfunction (e.g., hydrocephalus) to more complicated late-stage diseases (e.g., Alzheimer's) and failure of CNS regeneration. This review will focus on choroid plexus development, outlining how early specializations may be exploited clinically. PMID:25784848

  17. Two dye combinations suitable for two-color/two-dye laser-induced fluorescence thermography for ethanol

    Science.gov (United States)

    Fenner, Andreas; Stephan, Peter

    2017-06-01

    This paper presents two dye combinations suitable for two-color/two-dye laser-induced fluorescence thermography for ethanol. Besides the temperature dependency of the fluorescence, the influences of laser fluence, dye concentration, pressure, dissolved air, and photobleaching are also discussed. The experimental data are compared with models and data available in literature. Based on this, parameter ranges for two-color/two-dye laser-induced fluorescence thermography applications can be determined.

  18. In-vivo multiphoton microscopy (MPM) of laser-induced optical breakdown (LIOB) in human skin (Conference Presentation)

    Science.gov (United States)

    Balu, Mihaela; Lentsch, Griffin; Korta, Dorota; Konig, Karsten; Kelly, Kristen M.; Tromberg, Bruce J.; Zachary, Christopher B.

    2017-02-01

    We use a multiphoton microscopy (MPM)-based clinical microscope (MPTflex, JenLab, Germany) to describe changes in human skin following treatment with a fractional non-ablative laser (PicoWay, Candela). The treatment was based on a fractionated picosecond Nd:YAG laser (1064 and 532nm, 3mJ and 1.5mJ (no attenuation), respectively maximum energy/pulse, 100 microbeams/6mmx6mm). Improvements in skin appearance resulting from treatment with this laser have been noted but optimizing the efficacy depends on a thorough understanding of the specific skin response to treatment. MPM is a nonlinear laser scanning microscopy technique that features sub-cellular resolution and label-free molecular contrast. MPM contrast in skin is derived from second-harmonic generation of collagen and two-photon excited fluorescence of NADH/FAD+, elastin, keratin, melanin. In this pilot study, two areas on the arm of a volunteer (skin type II) were treated with the picoWay laser (1064nm, 3mJ; 532nm, 1.5mJ; 1pass). The skin response to treatment was imaged in-vivo at 8 time points over the following 4 weeks. MPM revealed micro-injuries present in epidermis. Damaged individual cells were distinguished after 3h and 24h from treatment with both wavelengths. Pigmented cells were particularly damaged in the process, suggesting that melanin is the main absorber and the primary target for laser induced optical breakdown. At later time points, clusters of cellular necrotic debris were imaged across the treated epidermis. These results represent the groundwork for future longitudinal studies on expanded number of subjects to understand the response to treatment in different skin types at different laser parameters, critical factors in optimizing treatment outcomes.

  19. FOCAL CHOROIDAL EXCAVATION AND ITS ASSOCIATION WITH PACHYCHOROID SPECTRUM DISORDERS: A Review of the Literature and Multimodal Imaging Findings.

    Science.gov (United States)

    Chung, Hyewon; Byeon, Suk Ho; Freund, K Bailey

    2017-02-01

    To review the literature regarding focal choroidal excavation and show its association with pachychoroid features through case examples. The clinical manifestations of focal choroidal excavation are illustrated with various imaging modalities inclusive of fundus photography, fundus autofluorescence, fluorescein angiography, indocyanine green angiography, spectral domain optical coherence tomography (OCT), enhanced depth imaging OCT, and swept-source OCT. Diffuse or focal areas of choroidal thickening with dilated choroidal vessels (pachyvessels) on OCT and choroidal hyperpermeability on indocyanine green angiography are present in many eyes with focal choroidal excavation. Clinical and imaging features of associated comorbidities including central serous chorioretinopathy and choroidal neovascularization are described. Focal choroidal excavation appears to be a manifestation of pachychoroid spectrum disease associated with choroidal thickening and pachyvessels on structural OCT and choroidal hyperpermeability on indocyanine green angiography.

  20. Retinal and choroidal intravascular spectral-domain optical coherence tomography

    DEFF Research Database (Denmark)

    Willerslev, Anne; Li, Xiao Qiang; Cordtz, Peter

    2014-01-01

    Purpose:  To examine retinal and choroidal blood vessels using spectral-domain optical coherence tomography (SD-OCT). Methods:  Retrospective case series. Results:  Scans through retinal blood vessels in healthy subjects demonstrated vessel wall reflexes and a tri-layer profile of the blood column...

  1. Choroidal metastases as the initial presentation of lung cancer: A ...

    African Journals Online (AJOL)

    Clinical reports of symptomatic intraocular metastasis as the initial presentation of lung cancer are rare. We report the case of a 49-year-old female patient who presented with loss of vision due to choroidal metastases as the initial manifestation of her disseminated lung cancer. This particular patient was referred to us from ...

  2. Choroidal Metastases as the Initial Presentation of Lung Cancer: A ...

    African Journals Online (AJOL)

    Clinical reports of symptomatic intraocular metastasis as the initial presentation of lung cancer are rare. We report the case of a 49-year-old female patient who presented with loss of vision due to choroidal metastases as the initial manifestation of her disseminated lung cancer. This particular patient was referred to us from.

  3. Large choroidal excavation in a patient with rubella retinopathy.

    Science.gov (United States)

    Battaglia Parodi, Maurizio; Romano, Francesco; Montagna, Marco; Bandello, Francesco

    2017-10-17

    To describe a case of rubella retinopathy complicated by bilateral choroidal neovascularization (CNV) and late development of large choroidal excavation (LCE). A 19-year-old woman with a diagnosis of rubella retinopathy underwent her annual ophthalmologic examination, including visual acuity testing and slit-lamp biomicroscopy with dilated fundus examination. Color fundus photography, spectral-domain optical coherence tomography (SD-OCT) scans, and optical coherence tomography angiography were acquired to complete the investigation of her ocular condition. The main findings are described in this case report. This woman came to our attention in 2010 with a history of rubella retinopathy, complicated by bilateral CNV and treated with photodynamic therapy (PDT) in 2006. After 6 years of annual follow-up examinations, her visual acuity remained stable in both eyes (20/100), whereas SD-OCT scans uncovered the development of a bilateral LCE in the macular area, associated with a macular hole in the right eye. Optical coherence tomography angiography revealed a vascular network surrounding the choroidal excavation. Large choroidal excavation is a rare finding that has been described in few chorioretinal diseases, e.g., North Carolina macular dystrophy and toxoplasmosis. We propose to include rubella retinopathy complicated by CNV in the differential diagnosis of LCE, although we recognize the possibility that PDT might have induced or facilitated its formation.

  4. Increased choroidal thickness in patient with high-altitude retinopathy

    Directory of Open Access Journals (Sweden)

    Kyoko Hirukawa-Nakayama

    2014-01-01

    Full Text Available We report a case of high-altitude retinopathy with increased choroidal thickness detected by spectral-domain optical coherence tomography (SD-OCT. A 36-year-old Japanese man developed an acute vision decrease in his left eye after he had trekked at an altitude of 4600 m in Tibet for 1 week. His visual acuity was 20/20 OD and 20/200 OS with refractive errors of − 0.25 diopters (D OD and − 0.50 D OS 3 weeks after the onset of the visual decrease. Funduscopic examinations revealed multiple intraretinal hemorrhages bilaterally and a macular hemorrhage in the left eye. SD-OCT showed that the thickness of choroidal layer at the fovea was 530 μm OD and 490 μm OS which is thicker than that in normal subjects of approximately 300 μm. We suggest that the increase in the retinal blood flow under hypoxic conditions may be associated with an increase in the choroidal blood flow resulting in an increase in choroidal thickness.

  5. Intraocular malignant melanoma of the choroid presenting as orbital cellulitis.

    Science.gov (United States)

    Nair, Akshay Gopinathan; Kaliki, Swathi; Ali, Mohammed Javed; Naik, Milind N; Vemuganti, Geeta K

    2014-06-01

    We report a case of choroidal melanoma with features suggestive of orbital cellulitis. A 24-year-old Asian Indian male presented with a 20-day history of sudden loss of vision in the right eye. Edematous eyelids with complete mechanical ptosis, complete ophthalmoplegia, gross proptosis accompanied by massive chemosis, and prolapse of the inferior forniceal conjunctiva were noted. He denied perception of light in the right eye. The left eye was unremarkable. B-scan ultrasonography of the right eye showed a large dome-shaped mass filling the posterior segment suggestive of choroidal melanoma. Computed tomography confirmed those findings and showed no extraocular tumor extension. The patient was conservatively treated with systemic steroids following which the inflammation subsided. He underwent enucleation of the right eye and a diagnosis of spindle A cell choroidal melanoma was confirmed by histopathological examination. Although rare, orbital cellulitis is one of the presenting features of choroidal melanoma. Uveal melanoma-associated orbital cellulitis can be well controlled with systemic steroids, does not always indicate extraocular tumor extension, and can occur in spindle A cell melanomas.

  6. OPTIC NERVE MENINGOCELE SIMULATING EXTRAOCULAR EXTENSION OF CHOROIDAL MELANOMA.

    Science.gov (United States)

    Sioufi, Kareem; Say, Emil Anthony T; Gray, Hilary M; Shields, Carol L

    2017-01-01

    To report a case of optic nerve meningocele simulating massive, recurrent extraocular extension of choroidal melanoma. Case report. A 53-year-old white man with choroidal melanoma in his left eye of 7.3-mm thickness was treated with plaque radiotherapy and transpupillary thermotherapy. On 1-year follow-up examination, visual acuity was 20/20 in the right eye and 20/30 in the left eye. The regressed choroidal melanoma scar in the left eye measured 1.5 mm in thickness with stable margins. The optic disk was normal. Ultrasonography demonstrated regressed echogenic choroidal scar, with an echolucent multilobulated retrobulbar mass, suspicious for extraocular extension. On magnetic resonance imaging, the retrobulbar mass corresponded to a distended and kinked optic nerve sheath, filled with extensive subarachnoid fluid and normal-size optic nerve with apposition against the posterior globe. There was no extraocular extension of tumor. Similar but less distended right optic nerve sheath was documented, consistent with optic nerve sheath meningocele in both eyes. Observation was advised and the findings remained stable. Optic nerve sheath meningocele is a benign dilatation of the optic nerve sheath that can simulate orbital tumor or extraocular extension of intraocular tumor. Magnetic resonance imaging can reliably differentiate these conditions.

  7. Retinal and choroidal angiogenesis: a review of new targets.

    Science.gov (United States)

    Cabral, Thiago; Mello, Luiz Guilherme M; Lima, Luiz H; Polido, Júlia; Regatieri, Caio V; Belfort, Rubens; Mahajan, Vinit B

    2017-01-01

    Retinal and choroidal neovascularization are a major cause of significant visual impairment, worldwide. Understanding the various factors involved in the accompanying physiopathology is vital for development of novel treatments, and most important, for preserving patient vision. The intraocular use of anti-vascular endothelial growth factor therapeutics has improved management of the retinal and choroidal neovascularization but some patients do not respond, suggesting other vascular mediators may also contribute to ocular angiogenesis. Several recent studies examined possible new targets for future anti-angiogenic therapies. Potential targets of retinal and choroidal neovascularization therapy include members of the platelet-derived growth factor family, vascular endothelial growth factor sub-family, epidermal growth factor family, fibroblast growth factor family, transforming growth factor-β superfamily (TGF-β1, activins, follistatin and bone morphogenetic proteins), angiopoietin-like family, galectins family, integrin superfamily, as well as pigment epithelium derived factor, hepatocyte growth factor, angiopoietins, endothelins, hypoxia-inducible factors, insulin-like growth factors, cytokines, matrix metalloproteinases and their inhibitors and glycosylation proteins. This review highlights current antiangiogenic therapies under development, and discusses future retinal and choroidal pro- and anti-angiogenic targets as wells as the importance of developing of new drugs.

  8. Choroid Plexus A-V Malformation Presenting with IVH

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2002-12-01

    Full Text Available A term infant presenting on the second day with apnea and decerebrate posturing had an intraventricular hemorrhage (IVH, the result of an arteriovenous malformation of the choroid plexus demonstrated angiographically on the 3rd day and reported from Johns Hopkins Hospital.

  9. Case Report: Bilateral iris, choroid, optic nerve colobomas and ...

    African Journals Online (AJOL)

    Background: Baraitser–Winter syndrome (BRWS) is a malformation syndrome, characterized by facial dysmorphism, ocular colobomata, pachygyria, and intellectual defects. Case report: A 3.5 year old female child with BRWS has bilateral congenital ptosis, microcornea, iris, choroid, and optic nerve coloboma, retinal ...

  10. Clinical Profile and Outcome of Serpiginous Choroiditis in a Uveitis ...

    African Journals Online (AJOL)

    tulyasys

    understanding of this disease.[10] The current treatment protocol for serpiginous choroiditis also remains controversial.[14,15] Although oral steroid remain the mainstay, there is often a need for immunosuppressive in view of non-response, recurrence, or steroid-induced side effects.[9,10,14,15] Antituberculous therapy was ...

  11. Bilateral pigmented paravenous retino-choroidal degeneration following measles.

    Science.gov (United States)

    Peduzzi, M; Guerrieri, F; Torlai, F; Prampolini, M L

    1984-01-01

    A 26-year-old female showed a bilateral ophthalmoscopic picture of pigmented paravenous retino-choroidal distrophy 19 years after neuro-retinitis following measles. Pigmentary disturbances in the fundus were not reported in 1963 clinical record; however functional tests are at present practically unchanged. Some debated aspects of this condition are discussed.

  12. Blue flicker modifies the subfoveal choroidal blood flow in the human eye.

    Science.gov (United States)

    Lovasik, John V; Kergoat, Hélène; Wajszilber, Marcelo A

    2005-08-01

    The objective of the present study was to reveal an interaction between choroidal blood flow (ChBF) and light-induced photoreceptor activity, a physiological coupling that has been already demonstrated for retinal blood flow but rejected for ChBF. Ten healthy adults volunteered for this study. A real-time recording near-infrared laser-Doppler flowmeter was used to quantify the subfoveal ChBF while the luminance of blue flicker between 1 and 64 Hz was first increased and then decreased by 4.0 log units in 1.0-log unit steps between 0.0375 and 375 cd/m2. In separate testing, flash electroretinograms (ERGs) provided electrophysiological indexes of the relative response of short-wave cones (s-cones) and rods to blue light stimulation. Group-averaged, normalized ChBF measurements revealed that it was modulated by approximately 9% by flicker frequency. Increasing the blue flicker luminance from low to high attenuated the subfoveal ChBF, volume, and velocity by approximately 32%, approximately 30%, and approximately 5%, respectively. Decreasing the luminance from high to low over the same range had no effect on the subfoveal choroidal hemodynamics. The markedly different effects of reversed directions of change in blue flicker luminance on the subfoveal ChBF were linked to transitions between rod-dominated and s-cone-dominated retinal responses. Collectively, these findings indicate that the blue light-induced photoreceptor response is associated with a differential distribution of the ChBF across the ocular fundus according to the degree and type of retinal photoreceptor stimulated.

  13. Autofluorescence quantification of benign and malignant choroidal nevomelanocytic tumors.

    Science.gov (United States)

    Albertus, Daniel L; Schachar, Ira H; Zahid, Sarwar; Elner, Victor M; Demirci, Hakan; Jayasundera, Thiran

    2013-08-01

    Accurate diagnosis of choroidal melanoma is challenging and has important implications for both physicians and patients. We assessed the utility of quantification of fundus autofluorescence in the evaluation and follow-up of choroidal nevomelanocytic tumors. To assess the utility of autofluorescence quantification in distinguishing clinically diagnosed choroidal nevi, melanoma, and indeterminate nevomelanocytic lesions. A retrospective observational study from 2006 to 2012 of patients with choroidal nevomelanocytic lesions who had digital autofluorescence and color fundus imaging performed at the University of Michigan Kellogg Eye Center. ImageJ software was used to output autofluorescence gray-scale values for each pixel of a 500 × 50-pixel region within each lesion and a corresponding adjacent control region. A single value was generated, termed the Index of Retinal Autofluorescence (IRA), to represent the total difference in gray-scale values between the 2 regions in each affected eye. Thirteen of the 14 clinically diagnosed nevi exhibited an IRA less than 150 gray-scale intensity squared (gsi2). Eight of 9 clinically diagnosed melanomas exhibited an IRA more than 150 gsi2. An IRA of 150 gsi2 distinguished nevi from melanomas with a sensitivity of 0.89 and specificity of 0.93. Fifteen of 19 patients with indeterminate nevomelanocytic lesions underwent clinical assessment and initial imaging with clinical follow-up at a median of 10 months. All 3 patients with an IRA less than 150 gsi2 showed no evidence of clinical progression and 6 of 12 lesions with an IRA more than 150 gsi2 showed clinical progression to melanoma. An IRA of 150 gsi2 identifies indeterminate lesions that progressed to melanoma with a sensitivity of 1.00 and specificity of 0.33. Quantification of digital autofluorescence images can differentiate between clinically benign and malignant choroidal nevomelanocytic lesions and may be predictive for clinical progression of indeterminate lesions.

  14. [Transpupillary thermotherapy (TTT) for intraocular metastases in choroid].

    Science.gov (United States)

    Romanowska-Dixon, Bozena; Kowal, Joanna; Pogrzebielski, Arkadiusz; Markiewicz, Anna

    2011-01-01

    Uveal metastases are the most common intraocular malignant tumors. Most patients who develop metastatic carcinoma to the choroid are managed by radiation or chemotherapy. Since TTT is an optional treatment for choroidal melanomas and hemangiomas, we ought to determine whether TIT is suitable for treatment of solitary choroidal metastasis at the posterior pole. To evaluate effectivenes of TTT treatment for intraocular metastases. 45 patients (59 eyes) with intraocular metastases were treated in the Ophthalmological Department of Jagiellonian University in Kraków. There were 30 women and 15 man, at the age 31-84 years (av. 57.5). The primary tumor was a breast cancer in 22 women, lung cancer in 5 men and 2 women, kidney (3), colon (2), uterus (1), larynx (1), testicle (1), esophagus (1). 10 patients had also metastases in other organs. TTT was performed in all treated eyes, in 11 combined with 106Ru brachytherapy (BT). Chemotherapy as adjuvant treatment was performed in 18 patients. The results of treatment were evaluated in mean 14.5 months (1-61) follow-up. After TTT, tumor shrinking was observed in most treated tumors (in 37 eyes, 62.7%), inhibition of tumor growth in 5 (8.4%), and in 4 cases (6.7%) progression of tumor growth. In 3 cases (5.1%) with flat scar and intraocular tumor shrinking, extrascleral extension located close to the tumor base appeared after treatment (TTT in 2 eyes, TTT combined with BT in one case). TTT is an effective treatment method for small choroidal metastases located in the posterior pole. TTT combined with 106Ru brachytherapy can be useful treatment in medium sized choroidal metastases. Efficient results encourage further application of thermotherapy in the treatment of intraocular metastases. It allows for the conservative treatment of the eyeball and also useful visual acuity. Extraocular extension appearing after TT needs further study.

  15. Optical Defocus Rapidly Changes Choroidal Thickness in Schoolchildren.

    Directory of Open Access Journals (Sweden)

    Danyang Wang

    Full Text Available The current study aimed to examine the short-term choroidal response to optical defocus in schoolchildren. Myopic schoolchildren aged 8-16 were randomly allocated to control group (CG, myopic defocus group (MDG and hyperopic defocus group (HDG (n = 17 per group. Children in MDG and HDG received additional +3D and -3D lenses, respectively, to their full corrections on the right eyes. Full correction was given to their left eyes, and on both eyes in the CG. Axial length (AXL and subfoveal choroidal thickness (SFChT were then measured by spectral domain optical coherence tomography. Children wore their group-specific correction for 2 hours after which any existing optical defocus was removed, and subjects wore full corrections for another 2 hours. Both the AXL and SFChT were recorded hourly for 4 hours. The mean refraction of all subjects was -3.41 ± 0.37D (± SEM. SFChT thinned when exposed to hyperopic defocus for 2 hours but less thinning was observed in response to myopic defocus compared to the control group (p < 0.05, two-way ANOVA. Removal of optical defocus significantly decreased SFChT in the MDG and significantly increased SFChT in the HDG after 1 and 2 hours (mean percentage change at 2-hour; control vs. hyperopic defocus vs. myopic defocus; -0.33 ± 0.59% vs. 3.04 ± 0.60% vs. -1.34 ± 0.74%, p < 0.01. Our results showed short-term exposure to myopic defocus induced relative choroidal thickening while hyperopic defocus led to choroidal thinning in children. This rapid and reversible choroidal response may be an important clinical parameter in gauging retinal response to optical defocus in human myopia.

  16. Quasi-resonance enhancement of laser-induced-fluorescence diagnosis of endometriosis

    Science.gov (United States)

    Hill, Ralph H., Jr.; Vancaillie, Thierry G.

    1990-05-01

    Endometriosis, a common disease in women in the reproductive age group, is defined pathologically by the presence of endometrial tissue (inner lining of the uterus) outside the uterus. The displaced tissue is histologically identical to endometrium. In addition to being a highly prevalent disease, this disease is associated with many distressing and debilitating symptoms. Motivated by the need to improve diagnosis by endoscopic imaging instrumentation, we have previously used several drugs to cause selective laser-induced fluorescence of active surgically induced endometriosis in the rabbit model in vivo using ultraviolet-wavelength (351.1 and 363.8 nm) excitation from an argon-ion laser. In the present study we have investigated methods of enhancing differentiation between normal and abnormal tissue by using other excitation wavelengths. In addition to an enhanced capability for detecting abnormal tissue, there are several other advantages associated with using visible-wavelength excitation, such as deeper penetration into the tissue, as well as increased equipment performance, reliability, versatility, and availability. The disadvantage is that because only wavelengths longer than the excitation wavelength can be used for detection, some of the spectral information is lost. Because human endomeiriosis samples were somewhat limited in quantity, as well as specimen size, we used normal ovarian tissue for the laser-induced-fluorescence differentiation-enhancement studies. Positive enhancement of the laser-induced- fluorescence differentiation was found in human ovarian tissue in vitro utilizing 514.5-nm excitation from an argonion laser. Additionally, preliminary verification of this concept was accomplished in active surgically induced endometriosis in the rabbit model in vivo with visible argon-ion laser excitation of two tetracycline-based drugs. Future experiments with other drug treatments and excitation/detection parameters are planned.

  17. Novel estimation of the humification degree of soil organic matter by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Edilene Cristina, E-mail: edilene@iq.unesp.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); São Paulo State University—UNESP, Analytical Chemistry Department, P.O. Box 355, 14801-970 Rua Prof. Francisco Degni, 55, CEP 14800-900 Araraquara, SP (Brazil); Ferreira, Ednaldo José, E-mail: ednaldo.ferreira@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Villas-Boas, Paulino Ribeiro, E-mail: paulino.villas-boas@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Senesi, Giorgio Saverio, E-mail: giorgio.senesi@ba.imip.cnr.it [Institute of Inorganic Methodologies and Plasmas, CNR, Bari 70126 (Italy); Carvalho, Camila Miranda, E-mail: camilamc@gmail.com [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Physics Institute of São Carlos, University of São Paulo, IFSC-USP, Av. Trabalhador são-carlense, 400 Pq. Arnold Schimid, 13566-590 São Carlos, SP (Brazil); Romano, Renan Arnon, E-mail: renan.romano@gmail.com [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Physics Institute of São Carlos, University of São Paulo, IFSC-USP, Av. Trabalhador são-carlense, 400 Pq. Arnold Schimid, 13566-590 São Carlos, SP (Brazil); Martin-Neto, Ladislau, E-mail: ladislau.martin@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); and others

    2014-09-01

    Soil organic matter (SOM) constitutes an important reservoir of terrestrial carbon and can be considered an alternative for atmospheric carbon storage, contributing to global warming mitigation. Soil management can favor atmospheric carbon incorporation into SOM or its release from SOM to atmosphere. Thus, the evaluation of the humification degree (HD), which is an indication of the recalcitrance of SOM, can provide an estimation of the capacity of carbon sequestration by soils under various managements. The HD of SOM can be estimated by using various analytical techniques including fluorescence spectroscopy. In the present work, the potential of laser-induced breakdown spectroscopy (LIBS) to estimate the HD of SOM was evaluated for the first time. Intensities of emission lines of Al, Mg and Ca from LIBS spectra showing correlation with fluorescence emissions determined by laser-induced fluorescence spectroscopy (LIFS) reference technique were used to obtain a multivaried calibration model based on the k-nearest neighbor (k-NN) method. The values predicted by the proposed model (A-LIBS) showed strong correlation with LIFS results with a Pearson's coefficient of 0.87. The HD of SOM obtained after normalizing A-LIBS by total carbon in the sample showed a strong correlation to that determined by LIFS (0.94), thus suggesting the great potential of LIBS for this novel application. - Highlights: • Humification degree of soil organic matter (HD) • Importance of soil organic matter HD in keeping carbon in soil • Laser induced fluorescence spectroscopy (LIFS) for HD estimation (reference method) • New LIBS application to predict HD.

  18. Influence of exothermic chemical reactions on laser-induced shock waves.

    Science.gov (United States)

    Gottfried, Jennifer L

    2014-10-21

    Differences in the excitation of non-energetic and energetic residues with a 900 mJ, 6 ns laser pulse (1064 nm) have been investigated. Emission from the laser-induced plasma of energetic materials (e.g. triaminotrinitrobenzene [TATB], cyclotrimethylene trinitramine [RDX], and hexanitrohexaazaisowurtzitane [CL-20]) is significantly reduced compared to non-energetic materials (e.g. sugar, melamine, and l-glutamine). Expansion of the resulting laser-induced shock wave into the air above the sample surface was imaged on a microsecond timescale with a high-speed camera recording multiple frames from each laser shot; the excitation of energetic materials produces larger heat-affected zones in the surrounding atmosphere (facilitating deflagration of particles ejected from the sample surface), results in the formation of additional shock fronts, and generates faster external shock front velocities (>750 m s(-1)) compared to non-energetic materials (550-600 m s(-1)). Non-explosive materials that undergo exothermic chemical reactions in air at high temperatures such as ammonium nitrate and magnesium sulfate produce shock velocities which exceed those of the inert materials but are less than those generated by the exothermic reactions of explosive materials (650-700 m s(-1)). The most powerful explosives produced the highest shock velocities. A comparison to several existing shock models demonstrated that no single model describes the shock propagation for both non-energetic and energetic materials. The influence of the exothermic chemical reactions initiated by the pulsed laser on the velocity of the laser-induced shock waves has thus been demonstrated for the first time.

  19. Quantitative emission from femtosecond microplasmas for laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Taschuk, M T; Kirkwood, S E; Tsui, Y Y; Fedosejevs, R [Department of Electical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada T6H 2V4 (Canada)

    2007-04-15

    An ongoing study of the scaling of Laser-Induced Breakdown Spectroscopy (LIBS) to microjoule pulse energies is being conducted to quantify the LIBS process. The use of microplasmas for LIBS requires good understanding of the emission scaling in order to maximize the sensitivity of the LIBS technique at low energies. The quantitative scaling of emission of Al, Cu and Si microplasmas from 100 {mu}J down to 100 nJ is presented. The scaling of line emission from major and minor constituents in Al 5052 alloy is investigated and evaluated for analytical LIBS. Ablated crater volume scaling and emission efficiency for Si microplasmas are investigated.

  20. Low power continuous wave laser induced optical nonlinearities in saffron ( Crocus Sativus L.)

    Science.gov (United States)

    Nasibov, H.; Mamedbeili, I.

    2010-12-01

    We report on the low power CW laser induced nonlinear optical responses of Saffron (stigmata of Crocus Savitus L.) ethanol and methanol extracts. The optical nonlinearities were investigated by performing Z-scan measurements at 470 and 535 nm wavelengths. At both wavelengths the material has a strong nonlinear refraction, mainly of thermal origin. However, only at 470 nm wavelength the material exhibit pronounced saturable nonlinear absorption. Long-term (70 days) stability measurements indicated that the nonlinearities in the Saffron extracts are due to their nonvolatile components. This study shows that there is great potential for Saffron extracts to be used in nonlinear photonic applications.

  1. Measurement of Eu and Yb in aqueous solutions by underwater laser induced breakdown spectroscopy

    Science.gov (United States)

    Bhatt, Chet R.; Jain, Jinesh C.; Goueguel, Christian L.; McIntyre, Dustin L.; Singh, Jagdish P.

    2017-11-01

    In this paper, we report the use of laser induced breakdown spectroscopy (LIBS) to detect dissolved Eu and Yb in bulk aqueous solutions. Ten strong emission lines of Eu and one strong emission line of Yb were identified in the underwater LIBS spectra obtained by using Czerny-Turner spectrometer within the wavelength range of 375-515 nm. Temporal evolution of plasma and the effect of laser pulse energy on the spectral emission were studied. Calibration curves using the concentration range from 500 to 10,000 ppm were developed and limits of detection for Eu and Yb were estimated to be 209 and 156 ppm, respectively.

  2. Laser-induced charge transfer in the HeH/sup 2 +/ quasimolecule

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Mendez, L.; Riera, A.

    1983-11-01

    In a recent publication, the charge transfer cross section for He/sup 2 +/+H(ls) collisions through photon-assisted 2psigma--3dsigma transitions was calculated; this calculation, however, contained several errors whose quantitative--even qualitative effect on the results is not obvious. We present a correct evaluation of this laser-induced cross section, which turns out to be larger, and present a maximum for longer wavelengths, than the values previously reported. In addition, we have checked the applicability of perturbation theory, of the stationary phase, uniform and Landau--Zener approximations, and the importance of potentially competitive photon-assisted reactions.

  3. Competitive immunoassay for clenbuterol using capillary electrophoresis with laser-induced fluorescence detection.

    Science.gov (United States)

    Zhou, Jieyu; Xu, Xueshu; Wang, Yuxiao

    2007-04-01

    A competitive immunoassay for detecting clenbuterol in urine was established by capillary electrophoresis (CE) with laser-induced fluorescence (LIF). The clenbuterol was conjugated with bovine serum albumin (BSA), and then the derivative was labeled with fluorescein isothiocyanate (FITC) and competes for antibody with free clenbuterol in the sample. Under the optimal conditions, Free and bound FITC labeled clenbuterol was separated within 8 min with the relative standard deviation (R.S.D.) 0.72% for migration time and 2.8% for peak area. The detection limit reached 0.7 ng/ml.

  4. Miniature endoscope for simultaneous optical coherence tomography and laser-induced fluorescence measurement

    Science.gov (United States)

    Tumlinson, Alexandre R.; Hariri, Lida P.; Utzinger, Urs; Barton, Jennifer K.

    2004-01-01

    We have designed a multimodality system that combines optical coherence tomography (OCT) and laser-induced fluorescence (LIF) in a 2.0-mm-diameter endoscopic package. OCT provides ~18-μm resolution cross-sectional structural information over a 6-mm field. LIF spectra are collected sequentially at submillimeter resolution across the same field and provide histochemical information about the tissue. We present the use of a rod prism to reduce the asymmetry in the OCT beam caused by a cylindrical window. The endoscope has been applied to investigate mouse colon cancer in vivo.

  5. Analysis of pigments in polychromes by use of laser induced breakdown spectroscopy and Raman microscopy

    Science.gov (United States)

    Castillejo, M.; Martín, M.; Silva, D.; Stratoudaki, T.; Anglos, D.; Burgio, L.; Clark, R. J. H.

    2000-09-01

    Two laser-based analytical techniques, Laser Induced Breakdown Spectroscopy (LIBS) and Raman microscopy, have been used for the identification of pigments on a polychrome from the Rococo period. Detailed spectral data are presented from analyses performed on a fragment of a gilded altarpiece from the church of Escatrón, Zaragoza, Spain. LIBS measurements yielded elemental analytical data which suggest the presence of certain pigments and, in addition, provide information on the stratigraphy of the paint layers. Identification of most pigments and of the materials used in the preparation layer was performed by Raman microscopy.

  6. Detection of lead in paint samples synthesized locally using-laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Gondal, Mohammed A; Nasr, Mohamed M; Ahmed, Mubarak M; Yamani, Zain H; Alsalhi, M S

    2011-01-01

    A laser-induced breakdown spectroscopy (LIBS) setup was developed to detect lead and other toxic contaminants such as chromium in paint emulsion samples manufactured in Saudi Arabia. The lead concentration detected in these samples was in the 327.2-755.3 ppm range, which is much higher than the safe permissible limit set by Saudi regulatory agencies. Similarly, chromium concentration (98.1-149.5 ppm) was found in high concentrations as well. The results obtained with our LIBS setup are comparable with the sample analysis utilizing a standard technique such as ICP, and our LIBS results are comparable to ICP with in an accuracy limit of 2-4 %.

  7. Printing of metallic 3D micro-objects by laser induced forward transfer.

    Science.gov (United States)

    Zenou, Michael; Kotler, Zvi

    2016-01-25

    Digital printing of 3D metal micro-structures by laser induced forward transfer under ambient conditions is reviewed. Recent progress has allowed drop on demand transfer of molten, femto-liter, metal droplets with a high jetting directionality. Such small volume droplets solidify instantly, on a nanosecond time scale, as they touch the substrate. This fast solidification limits their lateral spreading and allows the fabrication of high aspect ratio and complex 3D metal structures. Several examples of micron-scale resolution metal objects printed using this method are presented and discussed.

  8. Analysis of Trace Elements in Leaves Using Laser-Induced Breakdown Spectroscopy

    OpenAIRE

    ZHANG, XU; Yao, Mingyin; Liu, Muhua; Lei, Zejian

    2011-01-01

    Part 1: GIS, GPS, RS and Precision Farming; International audience; Laser-Induced Breakdown Spectroscopy (LIBS) is a new way to analyze the plant ecology. The experimental used a Q-switched Nd:YAG laser to be the laser source and equipped with an eight-channel model spectrometer which’s wavelength range between 200 and 1100 nm. Studying the spectrum of the air-drying leaves and the nature leaves and detected the elements which contain Fe, Ca, Na, Mg, K, Cu, Al and Mn. Displaying the list whic...

  9. Laser induced breakdown spectroscopy for heavy metal detection in a sand matrix

    Science.gov (United States)

    Michel, Anna P. M.; Sonnichsen, Frederick

    2016-11-01

    Sediments in many locations, including harbors and coastal areas, can become contaminated and polluted, for example, from anthropogenic inputs, shipping, human activities, and poor waste management. Sampling followed by laboratory analysis has been the traditional methodology for such analysis. In order to develop rapid methodologies for field analysis of sediment samples, especially for metals analyses, we look to Laser Induced Breakdown Spectroscopy as an option. Here through laboratory experiments, we demonstrate that dry sand samples can be rapidly analyzed for the detection of the heavy metals chromium, zinc, lead, and copper. We also demonstrate that cadmium and nickel are detectable in sand matrices at high concentrations.

  10. Dual-Wavelength In Situ Pyrometry During Additive Formation of Fibers by Laser-Induced Deposition

    Science.gov (United States)

    Vinson, Katherine; Maxwell, James; Hooper, Ryan J.; Allen, Jimmy; Thompson, Gregory B.

    2017-11-01

    A dual-wavelength pyrometry system has been demonstrated for measuring the reaction zone temperature for a series of carbon and SiC fibers grown additively by hyperbaric-pressure laser-induced chemical vapor deposition. The results demonstrate an inverse relationship between reaction zone size and temperature measurement noise. Though the noise can obscure transient effects associated with unstable growth, use of individual wavelength signals has been demonstrated as a means to deconvolute these features. Consequently, the use of in situ temperature measurements helps to link the final morphology of the fiber to its real-time growth behavior.

  11. Field Observations with Laser-Induced Fluorescence Transient (LIFT Method in Barley and Sugar Beet

    Directory of Open Access Journals (Sweden)

    Anna R. Raesch

    2014-05-01

    Full Text Available The laser-induced fluorescence transient (LIFT method is a non-invasive remote sensing technique for measurement of photosynthetic performance of plants under laboratory and field conditions. We report here a long-term comparative study to monitor the performance of different cultivars of barley and sugar beet during the growth season of these crops. The LIFT measurements provided useful results about photosynthetic light use efficiency on selected leaves in the canopy of the studied crops. The different canopy architectures, with different optical properties, influenced the LIFT measurements.

  12. Experimental Research of Reliability of Plant Stress State Detection by Laser-Induced Fluorescence Method

    Directory of Open Access Journals (Sweden)

    Yury Fedotov

    2016-01-01

    Full Text Available Experimental laboratory investigations of the laser-induced fluorescence spectra of watercress and lawn grass were conducted. The fluorescence spectra were excited by YAG:Nd laser emitting at 532 nm. It was established that the influence of stress caused by mechanical damage, overwatering, and soil pollution is manifested in changes of the spectra shapes. The mean values and confidence intervals for the ratio of two fluorescence maxima near 685 and 740 nm were estimated. It is presented that the fluorescence ratio could be considered a reliable characteristic of plant stress state.

  13. Laser-Induced Fluorescence and Performance Analysis of the Ultra-Compact Combustor

    Science.gov (United States)

    2008-06-01

    value LII Laser-induced incandescence LPT Low-pressure turbine Nd:YAG Neodymium-doped yttrium aluminium garnet PIV Particle imaging velocimetry PLIF...velocity spinning in the cavity, the air holes are drilled at a 45-degree angle. The inner side of the UCC cavity is left open to the main flow to...designed and cut. This sleeve, shown in Figure 43 fits snugly into the exhaust end of the main vane and has a 5 x 5 mm grid of holes cut into it

  14. Investigation of laser-induced damage by various initiators on the subsurface of fused silica.

    Science.gov (United States)

    Gao, Xiang; Feng, Guoying; Han, Jinghua; Zhai, Lingling

    2012-09-24

    We develop a model that describes the effect of size distribution of nanoabsorbers on the subsurface of fused silica on laser-damage probability. Using Mie theory and heat equation, we obtain the correlation between the critical fluence and particle radius. Considering a power law distribution of nanoabsorbers, the curves of laser-damage probability are calculated based on experimental results of contents of contaminations and a fit parameter of size distribution of nanoabsorbers. This paper presents the influence of various potential candidates, jointly, on laser-induced damage.

  15. Laser-induced photodynamic effects at silica nanocomposite based on cadmium sulphide quantum dots.

    Science.gov (United States)

    Voznesenskiy, S S; Sergeev, A A; Galkina, A N; Kulchin, Yu N; Shchipunov, Yu A; Postnova, I V

    2014-01-27

    In this paper we study the laser-induced modification of optical properties of nanocomposite based on cadmium sulphide quantum dots encapsulated into thiomalic acid shell which were embedded into a porous silica matrix. We found red shift of luminescence of the nanocomposite when exposed to laser radiation at λ = 405 nm. Using pump-probe method and Small-Angle X-ray Scattering technique it was found that laser radiation at λ = 405 nm also increases the absorption coefficient of the nanocomposite in 15 times due to agglomeration of quantum dots. The modification of absorption properties is fully reversible.

  16. Transient transmittance and scattering changes during nanosecond laser-induced damage in fused silica

    Science.gov (United States)

    Cao, Zhen; Hu, Guohang; He, Hongbo; Zhao, Yuanan; Yang, Liujiang; Luo, Yang; Peng, Xiaocong; Shan, Yao

    2017-08-01

    Transient transmission and scattering changes was observed to study the dynamics during the laser-induced bulk damage in fused silica at the wavelength of 532 and 355 nm. Within the nanosecond high power laser irradiation, the transmittance decreased dramatically, indicating an intense absorption. With fluence increasing, the time required to form the intense absorption was shortened, and at similar fluence, this time interval at the wavelength of 355 nm is shorter than that at 532 nm. At times, the intense absorption did not cause the macroscopic damage because no variation in scattering was observed. While the macroscopic damage occurred, the scattering kept on increasing until the end of pulse.

  17. Sub-Microsecond Temperature Measurement in Liquid Water Using Laser Induced Thermal Acoustics

    Science.gov (United States)

    Alderfer, David W.; Herring, G. C.; Danehy, Paul M.; Mizukaki, Toshiharu; Takayama, Kazuyoshi

    2005-01-01

    Using laser-induced thermal acoustics, we demonstrate non-intrusive and remote sound speed and temperature measurements over the range 10 - 45 C in liquid water. Averaged accuracy of sound speed and temperature measurements (10 s) are 0.64 m/s and 0.45 C respectively. Single-shot precisions based on one standard deviation of 100 or greater samples range from 1 m/s to 16.5 m/s and 0.3 C to 9.5 C for sound speed and temperature measurements respectively. The time resolution of each single-shot measurement was 300 nsec.

  18. Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-06-01

    A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

  19. Detection of indoor biological hazards using the man-portable laser induced breakdown spectrometer.

    Science.gov (United States)

    Munson, Chase A; Gottfried, Jennifer L; Snyder, Emily Gibb; De Lucia, Frank C; Gullett, Brian; Miziolek, Andrzej W

    2008-11-01

    The performance of a man-portable laser induced breakdown spectrometer was evaluated for the detection of biological powders on indoor office surfaces and wipe materials. Identification of pure unknown powders was performed by comparing against a library of spectra containing biological agent surrogates and confusant materials, such as dusts, diesel soot, natural and artificial sweeteners, and drink powders, using linear correlation analysis. Simple models constructed using a second technique, partial least squares discriminant analysis, successfully identified Bacillus subtilis (BG) spores on wipe materials and office surfaces. Furthermore, these models were able to identify BG on materials not used in the training of the model.

  20. Laser-induced fusion of human embryonic stem cells with optical tweezers

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shuxun; Wang Xiaolin; Sun Dong [Department of Mechanical and Biomedical Engineering, City University of Hong Kong (Hong Kong); Cheng Jinping; Han Cheng, Shuk [Department of Biology and Chemistry, City University of Hong Kong (Hong Kong); Kong, Chi-Wing [Stem Cell and Regenerative Medicine Consortium, and Departments of Medicine and Physiology, LKS Faculty of Medicine, University of Hong Kong (Hong Kong); Li, Ronald A. [Stem Cell and Regenerative Medicine Consortium, and Departments of Medicine and Physiology, LKS Faculty of Medicine, University of Hong Kong (Hong Kong); Center of Cardiovascular Research, Mount Sinai School of Medicine, New York, New York 10029 (United States)

    2013-07-15

    We report a study on the laser-induced fusion of human embryonic stem cells (hESCs) at the single-cell level. Cells were manipulated by optical tweezers and fused under irradiation with pulsed UV laser at 355 nm. Successful fusion was indicated by green fluorescence protein transfer. The influence of laser pulse energy on the fusion efficiency was investigated. The fused products were viable as gauged by live cell staining. Successful fusion of hESCs with somatic cells was also demonstrated. The reported fusion outcome may facilitate studies of cell differentiation, maturation, and reprogramming.

  1. Roughness effects on the hydrogen signal in laser-induced breakdown spectroscopy

    DEFF Research Database (Denmark)

    Rapin, W.; Bousquet, B.; Lasue, J.

    2017-01-01

    On Mars, Laser-Induced Breakdown Spectroscopy (LIBS) as performed by the ChemCam instrument can be used to measure the hydrogen content of targets in situ, under a low pressure CO2 atmosphere. However, unexpected variations observed in the Martian dataset suggest an effect related to target...... to hydrogen, as other emission lines in the spectra are not affected. The increase of the signal could be related to an addition of hydrogen to the plasma due to interaction with the surrounding target surface, yet the exact physical process to explain such effect remains to be identified. More generally...

  2. Characterization of femtosecond-laser-induced periodic structures on SiC substrates

    Science.gov (United States)

    Miyagawa, Reina; Ohno, Yutaka; Deura, Momoko; Yonenaga, Ichiro; Eryu, Osamu

    2018-02-01

    We investigated the crystalline state of femtosecond-laser-induced periodic structures using a transmission electron microscope (TEM). The core of the 200-nm-pitch periodic nanostructures on SiC retained a high crystalline quality continued from the SiC substrate, where the crystal orientation was aligned with that of the SiC substrate. These results suggest that the periodic nanostructures were formed by periodic etching and not by rearrangement. At high laser power, microstructures with sizes larger than 2 µm were formed on the periodic nanostructures. The microstructures were amorphous and extended from the amorphous SiC layer that covered the periodic nanostructures.

  3. Experimental Study of the Laser-Induced Oxyhemoglobin Photodissociation in Cutaneous Blood Vessels

    Directory of Open Access Journals (Sweden)

    Gisbrecht Alexander

    2015-11-01

    Full Text Available A new optical method for reduction of local tissue hypoxia is proposed. It is shown that this method of phototherapy allows the control of a local oxygen concentration in tissue. Different aspects of biomedical application of this phenomenon are discussed. The results of in vivo experimental investigation of the laser-induced photodissociation of oxyhemoglobin in cutaneous blood vessels and its role in tissue oxygenation are presented. The rates of oxygen saturation SpO2 in blood and their dependence on the wavelength of the transcutaneous laser irradiation have been experimentally measured.

  4. All-fiber probe for laser-induced thermotherapy with integrated temperature measurement capabilities

    Science.gov (United States)

    Liu, Y.; Chen, W.; Yu, H.; Gassino, R.; Braglia, A.; Olivero, M.; Perrone, Guido; Vallan, A.

    2015-03-01

    The paper presents our recent results towards the development of a miniaturized all-fiber probe for laser induced thermal ablation of tumor cells, which combines the optimal delivery of a near-infrared high power ablating beam, a low power visible aiming beam and fast Bragg grating (FBG) temperature sensors. Specific combiner and probe end-cap based on dual cladding fibers have been developed to allow the simultaneous handling of the laser beams and of the signal that feeds the temperature sensor. Moreover, a very fast FBG interrogation system has been implemented to track abrupt temperature variations during medical treatment.

  5. Change in refractive index of muscle tissue during laser-induced interstitial thermotherapy.

    Science.gov (United States)

    Chen, Na; Chen, Meimei; Liu, Shupeng; Guo, Qiang; Chen, Zhenyi; Wang, Tingyun

    2014-01-01

    This paper presents a long-period fiber-grating (LPG) based Michelson interferometric refractometry to monitor the change in refractive index of porcine muscle during laser-induced interstitial thermotherapy (LITT). As the wavelength of RI interferometer alters with the change in refractive index around the probe, the LPG based refractometry is combined with LITT system to measure the change in refractive index of porcine muscle when irradiated by laser. The experimental results show the denaturation of tissue alters the refractive index significantly and the LPG sensor can be applied to monitor the tissue state during the LITT.

  6. Time-resolved laser-induced incandescence from multiwalled carbon nanotubes in air

    Energy Technology Data Exchange (ETDEWEB)

    Mitrani, J. M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA; Shneider, M. N. [Department of Mechanical Engineering, Princeton University, Princeton, New Jersey 08544, USA

    2015-01-26

    We observed temporal laser-induced incandescence (LII) signals from multiwalled carbon nanotubes(MWCNTs) suspended in ambient air. Unlike previous LII experiments with soot particles, which showed that primary particles with larger diameters cool at slower timescales relative to smaller particles, we observed that thicker MWCNTs with larger outer diameters (ODs) cool at faster timescales relative to thinner MWCNTs with smaller ODs. We suggested a simple explanation of this effect, based on the solution of one-dimensional nonstationary heat conduction equation for the initial non-uniform heating of MWCNTs with ODs greater than the skin depth.

  7. Laser induced deflection technique for absolute thin film absorption measurement: optimized concepts and experimental results.

    Science.gov (United States)

    Mühlig, Christian; Kufert, Siegfried; Bublitz, Simon; Speck, Uwe

    2011-03-20

    Using experimental results and numerical simulations, two measuring concepts of the laser induced deflection (LID) technique are introduced and optimized for absolute thin film absorption measurements from deep ultraviolet to IR wavelengths. For transparent optical coatings, a particular probe beam deflection direction allows the absorption measurement with virtually no influence of the substrate absorption, yielding improved accuracy compared to the common techniques of separating bulk and coating absorption. For high-reflection coatings, where substrate absorption contributions are negligible, a different probe beam deflection is chosen to achieve a better signal-to-noise ratio. Various experimental results for the two different measurement concepts are presented.

  8. Transformation of microcrystalline silicon films by excimer-laser-induced crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, I.-C. [Department of Electrical Engineering, Da-Yeh University, Changhua 515, Taiwan (China); Lien, S.-Y. [Department of Materials Engineering, National Chung Hsing University, 250 Kuo Kuang Rd., Taichung Taiwan 402, (China); Wuu, D.-S. [Department of Materials Engineering, National Chung Hsing University, 250 Kuo Kuang Rd., Taichung Taiwan 402 (China)]. E-mail: dsw@dragon.nchu.edu.tw

    2005-02-01

    We describe the excimer-laser-induced crystallization of microcrystalline silicon films deposited by plasma-enhanced chemical vapor deposition (PECVD). Microcrystalline silicon films containing 2 at.% hydrogen can be used as precursor films for the laser recrystallization process without a dehydrogenation step, and provide a wider laser energy fluence process window than the previous explosive recrystallization for low temperature polysilicon (poly-Si) thin-film transistor (TFT) fabrication. Ellipsometry, transmission electron microscopy (TEM), and atomic force microscopy (AFM) are used to evaluate the laser irradiated films. Specially, we describe using atomic force microscopy to obtain plane-view grain microstructure images.

  9. Activation analysis of indium, KCl, and melamine by using a laser-induced neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungman; Lee, Kitae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cha, Hyungki [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2014-04-15

    A laser-induced repetitively operated fast neutron source with a neutron yield of 4 x 10{sup 5} n/pulse and a pulse repetition rate of 5 Hz, which was developed using a deuterated polystyrene film target and a 24-TW femtosecond laser, was applied for laser activation analyses of indium, KCl, and melamine samples. The nuclear reactions of the measured gamma spectra for the activated samples were identified as (n, γ), (n, n'), and (n, 2n) reactions. These indicate possible usage of the neutron source for practical activation analyses of various materials.

  10. Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Drew; Scime, Earl; Short, Zachary, E-mail: zdshort@mix.wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26056 (United States)

    2016-11-15

    Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration. We determine that the ratio of the TALIF cross sections of xenon and hydrogen is 0.024 ± 0.001.

  11. Heat generation above break-even from laser-induced fusion in ultra-dense deuterium

    OpenAIRE

    Leif Holmlid

    2015-01-01

    Previous results from laser-induced processes in ultra-dense deuterium D(0) give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u−1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu) cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NT...

  12. A study of ps-laser-induced-damage-threshold in hybrid metal-dielectric mirrors

    Science.gov (United States)

    Škoda, Václav; Vanda, Jan

    2014-10-01

    Laser-induced-damage-threshold of two types of metal-dielectric mirrors was tested using a laser apparatus working at 800 nm wavelength with 1 ps pulse length at 1 kHz repetition rate and in 106-on-1 test mode. Four sets of mirror samples with different layer system designs using a multilayer Ta2O5/SiO2 coating on silver or gold metal layer were manufactured. Both BK7 and fused silica substrate materials were used for manufacturing of samples. The measured damage thresholds at 45 deg incidence and P-polarization were compared with computed properties of layer system and used materials.

  13. Formation of organic layer on femtosecond laser-induced periodic surface structures

    Science.gov (United States)

    Yasumaru, Naoki; Sentoku, Eisuke; Kiuchi, Junsuke

    2017-05-01

    Two types of laser-induced periodic surface structures (LIPSS) formed on titanium by femtosecond (fs) laser pulses (λ = 800 nm, τ = 180 fs, ν = 1 kHz) in air were investigated experimentally. At a laser fluence F above the ablation threshold, LIPSS with a minimum mean spacing of D organic thin film similar to a cellulose derivative that cannot be easily formed by conventional chemical synthesis. The results of these surface analyses indicate that these two types of LIPSS are formed through different mechanisms. This fs-laser processing technique may become a new technology for the artificial synthesis of cellulose derivatives.

  14. Spectroscopic studies of different brands of cigarettes using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Sayyad, M. H.; Saleem, M.; Shah, M.; Shaikh, N. M.; Baig, M. A.

    2008-05-01

    In this work the technique of laser-induced breakdown spectroscopy (LIBS) has been used for the elemental analysis of cigarettes. For this purpose emission spectra have been measured of eleven different kinds of cigarette brands sold and/or produced in Pakistan. Analysis of the spectral peaks observed shows that Na, Mg, Al, K, Ca, Cr, Fe, Sr and Ba are contained in all brands. Exhibiting the LIBS results, the powerful potential of this method for the identification of the elemental content of cigarettes is demonstrated.

  15. Laser-induced incandescence of suspended particles as a source of excitation of dye luminescence

    CERN Document Server

    Zelensky, S

    2003-01-01

    The interaction of pulsed YAG-Nd sup 3 sup + laser radiation with submicron light-absorbing particles suspended in an aqueous solution of Rhodamine 6G is investigated experimentally. The experiments demonstrate that the laser-induced incandescence of suspended particles excites the luminescence of the dissolved dye molecules. The mechanism of the luminescence excitation consists in the reabsorption of the thermal radiation within the volume of the sample cell. On the ground of this mechanism of excitation, a method of measurement of the luminescence quantum yield is proposed and realized. The method requires the knowledge of the geometrical parameters of the cell and does not require the use of reference samples.

  16. Laser-induced narrowband coherent synchrotron radiation: Efficiency versus frequency and laser power

    Directory of Open Access Journals (Sweden)

    C. Evain

    2010-09-01

    Full Text Available We analyze the narrowband terahertz emission process occurring from electron bunches passing in a bending magnet, after a laser-induced sinusoidal modulation has been performed. In particular, we focus on experimental tunability curves, and power scalings with current and laser power. Theoretically, we simplify the problem formulation using the slowly varying envelope approximation. At low powers, the scaling with laser power appears to be quadratic, and analytical expressions for the tuning curves are obtained. Emission at first passage in the bending magnet, and after one full turn in the storage ring, are considered both experimentally and theoretically. The experiments are performed on the UVSOR-II storage ring.

  17. Photonic structures in diamond based on femtosecond UV laser induced periodic surface structuring (LIPSS).

    Science.gov (United States)

    Granados, Eduardo; Martinez-Calderon, Miguel; Gomez, Mikel; Rodriguez, Ainara; Olaizola, Santiago M

    2017-06-26

    We study the fabrication of photonic surface structures in single crystal diamond by means of highly controllable direct femtosecond UV laser induced periodic surface structuring. By appropriately selecting the excitation wavelength, intensity, number of impinging pulses and their polarization state, we demonstrate emerging high quality and fidelity diamond grating structures with surface roughness below 1.4 nm. We characterize their optical properties and study their potential for the fabrication of photonic structure anti-reflection coatings for diamond Raman lasers in the near-IR.

  18. Laser-induced Stress Wave-assisted Gene Transfection with Cationic Liposome

    Science.gov (United States)

    Terakawa, Mitsuhiro; Otsuka, Risa; Sato, Shunichi; Satoh, Yasushi; Takishima, Kunio; Ashida, Hiroshi; Okano, Hideyuki; Obara, Minoru

    2007-12-01

    We showed that efficiency of gene transfer using laser-induced stress waves (LISWs) can be drastically enhanced by modifying plasmid DNA with cationic liposome. Cultured NIH 3T3 cells were covered with a suspension including plasmid DNA that had been modified with Lipofectamine, and a laser target was placed over the suspension. The cells were exposed to stress waves generated by irradiation of the laser target with 6-ns laser pulses. The cells showed a significantly higher transfection efficiency compared with that of cells treated with LISWs alone or Lipofectamine alone.

  19. Escherichia coli identification and strain discrimination using nanosecond laser-induced breakdown spectroscopy

    Science.gov (United States)

    Rehse, Steven; Diedrich, Jonathan; Palchaudhuri, Sunil

    2007-06-01

    Three strains of Escherichia coli, one strain of black mold and one strain of Candida albicans yeast have been analyzed by laser-induced breakdown spectroscopy (LIBS) using nanosecond laser pulses. All microorganisms were analyzed while still alive and with no sample preparation. Nineteen atomic and ionic emission lines have been identified in the spectrum, which is dominated by calcium, magnesium and sodium. A discriminant function analysis (DFA) has been used to discriminate between the bio-types and E. coli strains. This is the first demonstration of the ability of the LIBS technique to differentiate between different strains of a single species.

  20. Wavelength dependence of picosecond laser-induced periodic surface structures on copper

    Science.gov (United States)

    Maragkaki, Stella; Derrien, Thibault J.-Y.; Levy, Yoann; Bulgakova, Nadezhda M.; Ostendorf, Andreas; Gurevich, Evgeny L.

    2017-09-01

    The physical mechanisms of the laser-induced periodic surface structures (LIPSS) formation are studied in this paper for single-pulse irradiation regimes. The change in the LIPSS period with wavelength of incident laser radiation is investigated experimentally, using a picosecond laser system, which provides 7-ps pulses in near-IR, visible, and UV spectral ranges. The experimental results are compared with predictions made under the assumption that the surface-scattered waves are involved in the LIPSS formation. Considerable disagreement suggests that hydrodynamic mechanisms can be responsible for the observed pattern periodicity.

  1. Determination of Rare Earth Elements in Geological Samples Using Laser-Induced Breakdown Spectroscopy (LIBS).

    Science.gov (United States)

    Bhatt, Chet R; Jain, Jinesh C; Goueguel, Christian L; McIntyre, Dustin L; Singh, Jagdish P

    2018-01-01

    Laser-induced breakdown spectroscopy (LIBS) was used to detect rare earth elements (REEs) in natural geological samples. Low and high intensity emission lines of Ce, La, Nd, Y, Pr, Sm, Eu, Gd, and Dy were identified in the spectra recorded from the samples to claim the presence of these REEs. Multivariate analysis was executed by developing partial least squares regression (PLS-R) models for the quantification of Ce, La, and Nd. Analysis of unknown samples indicated that the prediction results of these samples were found comparable to those obtained by inductively coupled plasma mass spectrometry analysis. Data support that LIBS has potential to quantify REEs in geological minerals/ores.

  2. Changes in Choroidal Thickness follow the RNFL Changes in Leber’s Hereditary Optic Neuropathy

    Science.gov (United States)

    Borrelli, Enrico; Triolo, Giacinto; Cascavilla, Maria Lucia; La Morgia, Chiara; Rizzo, Giovanni; Savini, Giacomo; Balducci, Nicole; Nucci, Paolo; Giglio, Rosa; Darvizeh, Fatemeh; Parisi, Vincenzo; Bandello, Francesco; Sadun, Alfredo A.; Carelli, Valerio; Barboni, Piero

    2016-01-01

    Leber’s hereditary optic neuropathy (LHON) is typically characterized by vascular alterations in the acute phase. The aim of this study was to evaluate choroidal changes occurring in asymptomatic, acute and chronic stages of LHON. We enrolled 49 patients with LHON, 19 with Dominant Optic Atrophy (DOA) and 22 healthy controls. Spectral Domain-Optical Coherence Tomography (SD-OCT) scans of macular and peripapillary regions were performed in all subjects, to evaluate macular and peripapillary choroidal thickness, and retinal nerve fiber layer (RNFL) thicknes. Macular and peripapillary choroidal thicknesses were significantly increased in the acute LHON stage. On the contrary, macular choroidal thickness was significantly reduced in the chronic stage. Furthermore, peripapillary choroidal thickness was decreased in chronic LHON and in DOA. Both RNFL and choroid had the same trend (increased thickness, followed by thinning), but RNFL changes preceded those affecting the choroid. In conclusion, our study quantitatively demonstrated the involvement of the choroid in LHON pathology. The increase in choroidal thickness is a feature of the LHON acute stage, which follows the thickening of RNFL. Conversely, thinning of the choroid is the common outcome in chronic LHON and in DOA. PMID:27853297

  3. Changes in Choroidal Thickness follow the RNFL Changes in Leber's Hereditary Optic Neuropathy.

    Science.gov (United States)

    Borrelli, Enrico; Triolo, Giacinto; Cascavilla, Maria Lucia; La Morgia, Chiara; Rizzo, Giovanni; Savini, Giacomo; Balducci, Nicole; Nucci, Paolo; Giglio, Rosa; Darvizeh, Fatemeh; Parisi, Vincenzo; Bandello, Francesco; Sadun, Alfredo A; Carelli, Valerio; Barboni, Piero

    2016-11-17

    Leber's hereditary optic neuropathy (LHON) is typically characterized by vascular alterations in the acute phase. The aim of this study was to evaluate choroidal changes occurring in asymptomatic, acute and chronic stages of LHON. We enrolled 49 patients with LHON, 19 with Dominant Optic Atrophy (DOA) and 22 healthy controls. Spectral Domain-Optical Coherence Tomography (SD-OCT) scans of macular and peripapillary regions were performed in all subjects, to evaluate macular and peripapillary choroidal thickness, and retinal nerve fiber layer (RNFL) thicknes. Macular and peripapillary choroidal thicknesses were significantly increased in the acute LHON stage. On the contrary, macular choroidal thickness was significantly reduced in the chronic stage. Furthermore, peripapillary choroidal thickness was decreased in chronic LHON and in DOA. Both RNFL and choroid had the same trend (increased thickness, followed by thinning), but RNFL changes preceded those affecting the choroid. In conclusion, our study quantitatively demonstrated the involvement of the choroid in LHON pathology. The increase in choroidal thickness is a feature of the LHON acute stage, which follows the thickening of RNFL. Conversely, thinning of the choroid is the common outcome in chronic LHON and in DOA.

  4. Choroid plexus dysfunction impairs beta-amyloid clearance in a triple transgenic mouse model of Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    Ibrahim eGonzález Marrero

    2015-02-01

    Full Text Available Compromised secretory function of choroid plexus (CP and defective cerebrospinal fluid (CSF production, along with accumulation of beta-amyloid (Aβ peptides at the blood-CSF barrier (BCSFB, likely contribute to complications of Alzheimer’s disease (AD. The AD triple transgenic mouse model (3xTg-AD at 16 month-old mimics several critical hallmarks of the human disease. In brain, the 3xTg-AD progressively develops β-amyloid (Aβ plaques and neurofibrillary tangles with a temporal- and regional- specific profile resembling their development in human AD. Currently, little is known about transport and metabolic responses by CP to the disrupted homeostasis of CNS Aβ in AD. This study analyzed the effects of highly-expressed AD-linked human transgenes (APP, PS1 and tau on lateral ventricle CP function. Confocal imaging and immunohistochemistry revealed an increase in Aβ42 (but not Aβ40 in epithelial cytosol and in stroma surrounding choroidal capillaries; the buildup in insoluble Aβ42 may reflect insufficient clearance transport from CSF to blood. Still, there was increased expression, presumably compensatory, of the choroidal Aβ transporters: the low density lipoprotein receptor-related protein 1 (LRP1 and the receptor for advanced glycation end product (RAGE. A thickening of the epithelial basal membrane and greater collagen IV deposition occurred around capillaries in CP of 3xTg-AD mice, probably curtailing solute exchanges. Moreover, there was attenuated expression of epithelial aquaporin-1 and transthyretin protein compared to non-Tg controls. Collectively these findings indicate CP dysfunction (hypothetically linked to increasing Aβ burden resulting in less efficient ion transport, concurrently with reduced production of cerebrospinal fluid (less sink action on brain Aβ and diminished secretion of transthyretin (less neuroprotection against cortical Aβ toxicity. The putative effects of a disabled CP-CSF system on CNS f

  5. Preliminary studies of laser-induced breakdown spectrometry for the determination of Ba, Cd, Cr and Pb in toys

    Science.gov (United States)

    Godoi, Quienly; Santos, Dario, Jr.; Nunes, Lidiane C.; Leme, Flávio O.; Rufini, Iolanda A.; Agnelli, José A. M.; Trevizan, Lilian C.; Krug, Francisco J.

    2009-06-01

    The performance of laser-induced breakdown spectrometry (LIBS) for the determination of Ba, Cd, Cr and Pb in toys has been evaluated by using a Nd:YAG laser operating at 1064 nm and an Echelle spectrometer with intensified charge-coupled device detector. Samples were purchased in different cities of São Paulo State market and analyzed directly without sample preparation. Laser-induced breakdown spectrometry experimental conditions (number of pulses, delay time, integration time gate and pulse energy) were optimized by using a Doehlert design. Laser-induced breakdown spectrometry signals correlated reasonably well with inductively coupled plasma optical emission spectrometry (ICP OES) concentrations after microwave-assisted acid digestion of selected samples. Thermal analysis was used for polymer identification and scanning electron microscopy to visualize differences in crater geometry of different polymers employed for toy fabrication. Results indicate that laser-induced breakdown spectrometry can be proposed as a rapid screening method for investigation of potentially toxic elements in toys. The unique application of laser-induced breakdown spectrometry for identification of contaminants in successive layers of ink and polymer is also demonstrated.

  6. Choroidal thinning in high myopia measured by optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Ikuno Y

    2013-05-01

    Full Text Available Yasushi Ikuno, Satoko Fujimoto, Yukari Jo, Tomoko Asai, Kohji NishidaDepartment of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, JapanPurpose: To investigate the rate of choroidal thinning in highly myopic eyes.Patients and methods: A retrospective observational study of 37 eyes of 26 subjects (nine males and 17 females, mean age 39.6 ± 7.7 years with high myopia but no pathologies who had undergone spectral domain optical coherence tomography and repeated the test 1 year later (1 ± 0.25 year at Osaka University Hospital, Osaka, Japan. Patients older than 50 years with visual acuity worse than 20/40 or with whitish chorioretinal atrophy involving the macula were excluded. Two masked raters measured the choroidal thicknesses (CTs at the foveda, 3 mm superiorly, inferiorly, temporally, and nasally on the images and averaged the values. The second examination was about 365 days after the baseline examination. The CT reduction per year (CTRPY was defined as (CT 1 year after - baseline CT/days between the two examinations × 365. The retinal thicknesses were also investigated.Results: The CTRPY at the fovea was −1.0 ± 22.0 µm (range –50.2 to 98.5 at the fovea, –6.5 ± 24.3 µm (range −65.8 to 90.2 temporally, –0.5 ± 22.3 µm (range –27.1 to 82.5 nasally, –9.7 ± 21.7 µm (range –40.1 to 60.1 superiorly, and –1.4 ± 25.5 µm (range –85.6 to 75.2 inferiorly. There were no significant differences in the CTRPY at each location (P = 0.34. The CT decreased significantly (P < 0.05 only superiorly. The superior CTRPY was negatively correlated with the axial length (P < 0.05. The retinal thickness at the fovea did not change. Stepwise analysis for CTRPY selected axial length (P = 0.04, R2 = 0.13 and age (P = 0.08, R2 = 0.21 as relevant factors.Conclusions: The highly myopic choroid might gradually thin and be affected by many factors. Location and axial length are key factors to regulate the rate of choroidal

  7. Laser induced breakdown spectroscopy (LIBS) as a rapid tool for material analysis

    Science.gov (United States)

    Hussain, T.; Gondal, M. A.

    2013-06-01

    Laser induced breakdown spectroscopy (LIBS) is a novel technique for elemental analysis based on laser-generated plasma. In this technique, laser pulses are applied for ablation of the sample, resulting in the vaporization and ionization of sample in hot plasma which is finally analyzed by the spectrometer. The elements are identified by their unique spectral signatures. LIBS system was developed for elemental analysis of solid and liquid samples. The developed system was applied for qualitative as well as quantitative measurement of elemental concentration present in iron slag and open pit ore samples. The plasma was generated by focusing a pulsed Nd:YAG laser at 1064 nm on test samples to study the capabilities of LIBS as a rapid tool for material analysis. The concentrations of various elements of environmental significance such as cadmium, calcium, magnesium, chromium, manganese, titanium, barium, phosphorus, copper, iron, zinc etc., in these samples were determined. Optimal experimental conditions were evaluated for improving the sensitivity of developed LIBS system through parametric dependence study. The laser-induced breakdown spectroscopy (LIBS) results were compared with the results obtained using standard analytical technique such as inductively couple plasma emission spectroscopy (ICP). Limit of detection (LOD) of our LIBS system were also estimated for the above mentioned elements. This study demonstrates that LIBS could be highly appropriate for rapid online analysis of iron slag and open pit waste.

  8. Laser induced fluorescence spectrum analysis of OH from photo-dissociation of water in gas phase

    Science.gov (United States)

    Li, Guohua; Ye, Jingfeng; Zhang, Zhengrong; Wang, Sheng; Hu, Zhiyun; Zhao, Xinyan

    2017-05-01

    The OH can be generated from photo-dissociation of water in the gas phase, and the generated OH has served in tagging velocimetry using the time-flight method. The hydroxyl tagging mechanism has the advantages of non-seeding, kindly flow following character, but its application in the reaction region is limited for the fluorescence interference from nascent OH. In this paper, we explored the laser induced fluorescence spectrum of OH both from burning and photodissociation. A photo-dissociation laser induced fluorescence (PD-LIF) system with optical multichannel analysis instrument (OMA) for spectrum analysis was developed. Based on multichannel mechanism, the LIF spectrum of OH from photo-dissociation and burning were acquired simultaneously. The temporal spectrum profiles of dissociation OH both in flame and air were taken by varying the pump-probe delay. The normalized emission spectrum in flame showed a process of rotational relaxation while in air the spectrum was almost not changed. The fluorescence intensity was precisely proportional to the base states population, so we can get certain states that the OH from dissociation was predominant from the fluorescence intensity ratio of OH. This result can be further utilized for hydroxyl tagging velocimetry technology (HTV) which was less affected by burning OH.

  9. Compositional Analysis of Aerosols Using Calibration-Free Laser-Induced Breakdown Spectroscopy.

    Science.gov (United States)

    Boudhib, Mohamed; Hermann, Jörg; Dutouquet, Christophe

    2016-04-05

    We demonstrate that the elemental composition of aerosols can be measured using laser-induced breakdown spectroscopy (LIBS) without any preliminary calibration with standard samples. Therefore, a nanosecond Nd:YAG laser beam was focused into a flux of helium charged with alumina aerosols of a few micrometers diameter. The emission spectrum of the laser-generated breakdown plasma was recorded with an echelle spectrometer coupled to a gated detector. The spectral features including emission from both the helium carrier gas and the Al2O3 aerosols were analyzed on the base of a partial local thermodynamic equilibrium. Thus, Boltzmann equilibrium distributions of population number densities were assumed for all plasma species except of helium atoms and ions. By analyzing spectra recorded for different delays between the laser pulse and the detector gate, it is shown that accurate composition measurements are only possible for delays ≤1 μs, when the electron density is large enough to ensure collisional equilibrium for the aerosol vapor species. The results are consistent with previous studies of calibration-free LIBS measurements of solid alumina and glass and promote compositional analysis of aerosols via laser-induced breakdown in helium.

  10. [A method for time-resolved laser-induced breakdown spectroscopy measurement].

    Science.gov (United States)

    Pan, Cong-Yuan; Han, Zhen-Yu; Li, Chao-Yang; Yu, Yun-Si; Wang, Sheng-Bo; Wang, Qiu-Ping

    2014-04-01

    Laser-Induced Breakdown Spectroscopy (LIBS) is strongly time related. Time-resolved LIBS measurement is an important technique for the research on laser induced plasma evolution and self-absorption of the emission lines. Concerning the temporal characteristics of LIBS spectrum, a method is proposed in the present paper which can achieve micros-scale time-resolved LIBS measurement by using general ms-scale detector. By setting different integration delay time of the ms-scale spectrum detector, a series of spectrum are recorded. And the integration delay time interval should be longer than the worst temporal precision. After baseline correction and spectrum fitting, the intensity of the character line was obtained. Calculating this intensity with differential method at a certain time interval and then the difference value is the time-resolved line intensity. Setting the plasma duration time as X-axis and the time-resolved line intensity as Y-axis, the evolution curve of the character line intensity can be plotted. Character line with overlap-free and smooth background should be a priority to be chosen for analysis. Using spectrometer with ms-scale integration time and a control system with temporal accuracy is 0.021 micros, experiments carried out. The results validate that this method can be used to characterize the evolution of LIBS characteristic lines and can reduce the cost of the time-resolved LIBS measurement system. This method makes high time-resolved LIBS spectrum measurement possible with cheaper system.

  11. Deflagration of Energetic Materials Initiated by Electrostatic Discharges and Laser-Induced Plasmas

    Science.gov (United States)

    Collins, Eric; Gottfried, Jennifer

    2017-06-01

    A laser-induced plasma and an electrostatic discharge were used for the ignition of small quantities (5-10 mg) of energetic materials. The laser-induced plasma was generated from a ns-pulsed Nd:YAG laser with energy output of 0.8 J per pulse and the electrostatic discharge was generated from a 0.035 μF capacitor that was charged to energy levels of up to 10 J. Although the durations and energy outputs of these two ignition mechanisms are very different, similarities in the initiation of the energetic materials include particle ejection from the target, heating of particles in the air from the plasma and spark, and a shockwave formation. The shock wave was measured and analyzed at various energy levels using schlieren imaging with a high speed camera. Diagnostics used to measure time-resolved temperatures, energy generation, and emission signatures of the deflagrations were high speed camera pyrometry, visible and infrared photo receivers, and a high-resolution spectrometer, respectively.

  12. Simultaneous analysis of Cr and Pb in contaminated pork by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Yao, Mingyin; Rao, Gangfu; Huang, Lin; Liu, Muhua; Yang, Hui; Chen, Jinyin; Chen, Tianbing

    2017-10-10

    Laser-induced breakdown spectroscopy (LIBS) as a rapid and green method was used to detect heavy metals Cr and Pb in pork contaminated in the lab. The laser-induced plasma was generated by a Q-switched Nd:YAG laser, and the LIBS signal was collected by a spectrometer with a charge-coupled device detector. The traditional calibration curves (CC) and multivariate partial least squares (PLS) algorithm were applied and compared to validate the accuracy in predicting the content of heavy metals in samples. The results demonstrated that the correlation coefficient of CC is poor by the classical univariate calibration method, so the univariate calibration analysis cannot effectively serve the quantitative purpose in analyzing heavy metals' residue in pork with a complex matrix. The analysis accuracy was improved effectively by the PLS method, and the correlation coefficient is 0.9894 for Cr and 0.9908 for Pb. The concentration of Cr and Pb in samples from a prediction set was obtained using the PLS calibration method, and the average relative errors for the 21 samples in the prediction set are lower than 6.53% and 7.82% for Cr and Pb, respectively. The investigated results display that the matrix effect would be reduced effectively during the quantitative analysis of pork by a LIBS-combined PLS model, and the predictive accuracy would be improved greatly compared to traditional univariate analysis.

  13. [Research on radiation intensity of nanosecond pulse laser-induced soil plasma].

    Science.gov (United States)

    Chen, Jin-zhong; Song, Guang-ju; Sun, Jiang; Li, Xu; Wei, Yan-hong

    2012-01-01

    To improve the quality of laser-induced breakdown spectroscopy, nanosecond pulse laser generated by Nd : YAG laser was used to excite soil sample. The laser-induced plasma spectrum was observed using a grating spectrometer and a photoelectric detection system. The influence of laser output energy ranging from 100 to 500 mJ on the radiation intensity of plasma was studied. The results show that both the line intensity and signal-to-background ratio can be enhanced under the optimized condition that the laser energy is 200 mJ. The quality of spectrum was further improved after the laser beam used to excite the sample was defocused properly. When the defocusing position is + 6 mm, the spectral lines intensity of element Mg, Al, K and Fe increased about 46%, 63%, 59% and 45% compared to that without defocusing respectively. The spectral signal-to-background ratio increased about 11%, 31%, 35% and 38% respectively. This lays a foundation for detection of trace impurity element in soil.

  14. Quantitative analyses of glass via laser-induced breakdown spectroscopy in argon

    Science.gov (United States)

    Gerhard, C.; Hermann, J.; Mercadier, L.; Loewenthal, L.; Axente, E.; Luculescu, C. R.; Sarnet, T.; Sentis, M.; Viöl, W.

    2014-11-01

    We demonstrate that elemental analysis of glass with a measurement precision of about 10% can be performed via calibration-free laser-induced breakdown spectroscopy. Therefore, plasma emission spectra recorded during ultraviolet laser ablation of different glasses are compared to the spectral radiance computed for a plasma in local thermodynamic equilibrium. Using an iterative calculation algorithm, we deduce the relative elemental fractions and the plasma properties from the best agreement between measured and computed spectra. The measurement method is validated in two ways. First, the LIBS measurements are performed on fused silica composed of more than 99.9% of SiO2. Second, the oxygen fractions measured for heavy flint and barite crown glasses are compared to the values expected from the glass composing oxides. The measured compositions are furthermore compared with those obtained by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. It is shown that accurate LIBS analyses require spectra recording with short enough delays between laser pulse and detector gate, when the electron density is larger than 1017 cm- 3. The results show that laser-induced breakdown spectroscopy based on accurate plasma modeling is suitable for elemental analysis of complex materials such as glasses, with an analytical performance comparable or even better than that obtained with standard techniques.

  15. Non-destructive evaluation of UV pulse laser-induced damage performance of fused silica optics.

    Science.gov (United States)

    Huang, Jin; Wang, Fengrui; Liu, Hongjie; Geng, Feng; Jiang, Xiaodong; Sun, Laixi; Ye, Xin; Li, Qingzhi; Wu, Weidong; Zheng, Wanguo; Sun, Dunlu

    2017-11-24

    The surface laser damage performance of fused silica optics is related to the distribution of surface defects. In this study, we used chemical etching assisted by ultrasound and magnetorheological finishing to modify defect distribution in a fused silica surface, resulting in fused silica samples with different laser damage performance. Non-destructive test methods such as UV laser-induced fluorescence imaging and photo-thermal deflection were used to characterize the surface defects that contribute to the absorption of UV laser radiation. Our results indicate that the two methods can quantitatively distinguish differences in the distribution of absorptive defects in fused silica samples subjected to different post-processing steps. The percentage of fluorescence defects and the weak absorption coefficient were strongly related to the damage threshold and damage density of fused silica optics, as confirmed by the correlation curves built from statistical analysis of experimental data. The results show that non-destructive evaluation methods such as laser-induced fluorescence and photo-thermal absorption can be effectively applied to estimate the damage performance of fused silica optics at 351 nm pulse laser radiation. This indirect evaluation method is effective for laser damage performance assessment of fused silica optics prior to utilization.

  16. Investigation of laser induced damage threshold measurement with single-shot on thin films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhichao, E-mail: zcliu44@163.com; Zheng, Yi; Pan, Feng; Lin, Qi; Ma, Ping; Wang, Jian

    2016-09-30

    Highlights: • Developed a rapid-testing method of the laser induced damage threshold for thin film surface within only one shot. • Comparison of single shot test and the ISO standard test has been performed on several types of reflectors. • Factors that impacted the measurement accuracy were discussed, and the optimization process was mentioned in this paper as well. - Abstract: A method for rapid determination of laser induced damage threshold (LIDT) of optical coatings is proposed and investigated in this paper. By use of this method, the LIDT of thin film can be rapidly obtained by only one shot. The modulation of laser beam profile, which is considered as a negative factor in conventional LIDT test, is utilized in this method. Basing on image processing technique, the damage information could be extracted from the comparison between the damage pattern and beam intensity distribution in the test region. The applicability and repeatability of this testing method has been verified on three type reflectors, HfO{sub 2}/SiO{sub 2}, HfO{sub 2}/Al{sub 2}O{sub 3} and Ta{sub 2}O{sub 5}/SiO{sub 2}. In addition, the experimental results showed that appropriate beam size, laser energy and image compression ratio are the key factors to ensure a high accuracy of LIDT.

  17. UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry in the diagnostics of alopecia

    Science.gov (United States)

    Skomorokha, Diana P.; Pigoreva, Yulia N.; Salmin, Vladimir V.

    2016-04-01

    Development of optical biopsy methods has a great interest for medical diagnostics. In clinical and experimental studies it is very important to analyze blood circulation quickly and accurately, thereby laser Doppler flowmetry (LDF) is widely used. UV laser-induced fluorescence spectroscopy (UV LIFS) is express highly sensitive and widely-spread method with no destructive impact, high excitation selectivity and the possibility to use in highly scattering media. The goal of this work was to assess a correlation of UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry parameters, and a possibility to identify or to differentiate various types of pathological changes in tissues according to their autofluorescence spectra. Three groups of patients with diffuse (symptomatic) alopecia, androgenic alopecia, and focal alopecia have been tested. Each groups consisted of not less than 20 persons. The measurements have been done in the parietal and occipital regions of the sculls. We used the original automated spectrofluorimeter to record autofluorescence spectra, and standard laser Doppler flowmeter BLF-21 (Transonic Systems, Inc., USA) to analyze the basal levels of blood circulation. Our results show that UV LIFS accurately distinguishes the zones with different types of alopecia. We found high correlation of the basal levels of blood circulation and the integrated intensity of autofluorescence in the affected tissue.

  18. Laser Induced Breakdown Spectroscopy in archeometry: A review of its application and future perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Spizzichino, Valeria, E-mail: valeria.spizzichino@enea.it; Fantoni, Roberta

    2014-09-01

    Laser Induced Breakdown Spectroscopy (LIBS) in the last decades has been more and more applied to the field of Cultural Heritage with great results obtained either alone or in combination with complementary laser techniques. Its ability to analyze, with a minimal loss, different kinds of materials in laboratory, in situ and even in hostile environments has been highly appreciated. The main aim of this paper is to present a review of LIBS applications in the interdisciplinary field of archeometry. The LIBS technique is shortly described both from a theoretical and practical point of view, discussing the instrumental setup, also in comparison with typical features of laser induced fluorescence (LIF) and Raman spectroscopy apparata. The complementary with multivariate analysis, a method that can help in reducing data set dimensions and in pulling out effective information, is stressed. In particular the role of LIBS in Cultural Heritage material characterization, recognition of fakes and indirect dating is described, reporting general considerations and case studies on metal alloys, mural paintings, decorated ceramics, glasses, stones and gems. - Highlights: • Applications of LIBS to archeometry are reviewed. • Complementary among LIBS, LIF, Raman and multivariate analysis is highlighted. • Three major areas of successful LIBS application in archeometry are identified. • Significant results have been presented for several different materials.

  19. Laser-induced breakdown spectroscopy for in situ qualitative and quantitative analysis of mineral ores

    Science.gov (United States)

    Pořízka, P.; Demidov, A.; Kaiser, J.; Keivanian, J.; Gornushkin, I.; Panne, U.; Riedel, J.

    2014-11-01

    In this work, the potential of laser-induced breakdown spectroscopy (LIBS) for discrimination and analysis of geological materials was examined. The research was focused on classification of mineral ores using their LIBS spectra prior to quantitative determination of copper. Quantitative analysis is not a trivial task in LIBS measurement because intensities of emission lines in laser-induced plasmas (LIP) are strongly affected by the sample matrix (matrix effect). To circumvent this effect, typically matrix-matched standards are used to obtain matrix-dependent calibration curves. If the sample set consists of a mixture of different matrices, even in this approach, the corresponding matrix has to be known prior to the downstream data analysis. For this categorization, the multielemental character of LIBS spectra can be of help. In this contribution, a principal component analysis (PCA) was employed on the measured data set to discriminate individual rocks as individual matrices against each other according to their overall elemental composition. Twenty-seven igneous rock samples were analyzed in the form of fine dust, classified and subsequently quantitatively analyzed. Two different LIBS setups in two laboratories were used to prove the reproducibility of classification and quantification. A superposition of partial calibration plots constructed from the individual clustered data displayed a large improvement in precision and accuracy compared to the calibration plot constructed from all ore samples. The classification of mineral samples with complex matrices can thus be recommended prior to LIBS system calibration and quantitative analysis.

  20. Spatial characterization of laser induced Yb plasma in argon using optical emission spectroscopy: Pressure effect

    Energy Technology Data Exchange (ETDEWEB)

    Jazmati, A.K.; Alnama, K., E-mail: pscientific21@aec.org.sy; Alkhawwam, A.

    2014-09-15

    Highlights: • Laser induced Yb plasma at different pressure of Argon is spatially investigated. • O-TOF profiles and excitation temperature are used to characterize the plasma. • At 100 Pa of argon background gas, shock wave begins to be formed. • Drag force expansion describes the plasma propagation at pressures bigger than 1 Pa. • Two components of velocity distribution of the Yb atoms are estimated. - Abstract: Spatial and temporal behavior of laser induced Ytterbium plasma plume is studied using optical emission spectroscopy technique. A third harmonic Nd:YAG nanosecond laser was used to generate Yb plasma plume at different Argon background pressures (1, 10, 10{sup 2}, 10{sup 3} and 10{sup 4} Pa). The plasma dynamics was investigated based on the spatial behavior of the excitation temperature coupled with optical time of flight (O-TOF) profiles of neutral Yb emission line (555.65 nm) along the propagation axe of the plasma plume. Drag force model was appropriate to describe the propagation dynamics at all pressures except of the lowest one (1 Pa) where free expansion model is dominant. The velocity distribution of Yb I atoms were extracted using two terms of Shifted Maxwell–Boltzmann (SMB) distribution. The correlation between the spatial comportment of both excitation temperature and O-TOF profiles is discussed.

  1. Laser-induced breathing modes in metallic nanoparticles: a symmetric molecular dynamics study.

    Science.gov (United States)

    Ng, Ming-Yaw; Chang, Yia-Chung

    2011-03-07

    A highly efficient simulation method based on molecular dynamics and group theory is adopted to investigate the laser-induced breathing oscillation of gold and silver nanospheres. Nanoparticles with size ranging from 5.8 to 46.2 nm are discussed. The effect due to laser-induced heating is modeled by a symmetric sudden expansion of the nanospheres by increasing the interatomic distances. A long-range empirical potential model which is capable of describing the phonon dispersion curves of noble metals in the full frequency range is established. Group theory is fully exploited to increase the computation efficiency, and the oscillation behavior of nanospheres of over 3 × 10(6) atoms can be simulated efficiently. Oscillation frequencies of nanospheres are obtained by calculating the Fourier transform of the velocity autocorrelation function. The breathing modes of nanospheres are identified as the excitation of A(1g) modes with in-phase radial displacement of atoms in the nanospheres. The resulting oscillation spectra are in very good agreement with experimental data. © 2011 American Institute of Physics.

  2. Detection and Classification of Live and Dead Escherichia coli by Laser-Induced Breakdown Spectroscopy

    Science.gov (United States)

    Sivakumar, P.; Fernández-Bravo, A.; Taleh, L.; Biddle, J.F.

    2015-01-01

    Abstract A common goal for astrobiology is to detect organic materials that may indicate the presence of life. However, organic materials alone may not be representative of currently living systems. Thus, it would be valuable to have a method with which to determine the health of living materials. Here, we present progress toward this goal by reporting on the application of laser-induced breakdown spectroscopy (LIBS) to study characteristics of live and dead cells using Escherichia coli (E. coli) strain K12 cells as a model organism since its growth and death in the laboratory are well understood. Our goal is to determine whether LIBS, in its femto- and/or nanosecond forms, could ascertain the state of a living organism. E. coli strain K12 cells were grown, collected, and exposed to one of two types of inactivation treatments: autoclaving and sonication. Cells were also kept alive as a control. We found that LIBS yields key information that allows for the discrimination of live and dead E. coli bacteria based on ionic shifts reflective of cell membrane integrity. Key Words: E. coli—Trace elements—Live and dead cells—Laser-induced breakdown spectroscopy—Atomic force microscopy. Astrobiology 15, 144–153. PMID:25683088

  3. Capillary electrophoresis hyphenated with UV-native-laser induced fluorescence detection (CE/UV-native-LIF).

    Science.gov (United States)

    Couderc, François; Ong-Meang, Varravaddheay; Poinsot, Véréna

    2017-01-01

    Native laser-induced fluorescence using UV lasers associated to CE offers now a large related literature, for now 30 years. The main works have been performed using very expensive Ar-ion lasers emitting at 257 and 275 nm. They are not affordable for routine analyses, but have numerous applications such as protein, catecholamine, and indolamine analysis. Some other lasers such as HeCd 325 nm have been used but only for few applications. Diode lasers, emitting at 266 nm, cheaper, are extensively used for the same topics, even if the obtained sensitivity is lower than the one observed using the costly UV-Ar-ion lasers. This review presents various CE or microchips applications and different UV lasers used for the excitation of native fluorescence. We showed that CE/Native UV laser induced fluorescence detection is very sensitive for detection as well as small aromatic biomolecules than proteins containing Trp and Tyr amino acids. Moreover, it is a simple way to analyze biomolecules without derivatization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Numerical analysis of quantitative measurement of hydroxyl radical concentration using laser-induced fluorescence in flame

    Science.gov (United States)

    Shuang, Chen; Tie, Su; Yao-Bang, Zheng; Li, Chen; Ting-Xu, Liu; Ren-Bing, Li; Fu-Rong, Yang

    2016-06-01

    The aim of the present work is to quantitatively measure the hydroxyl radical concentration by using LIF (laser-induced fluorescence) in flame. The detailed physical models of spectral absorption lineshape broadening, collisional transition and quenching at elevated pressure are built. The fine energy level structure of the OH molecule is illustrated to understand the process with laser-induced fluorescence emission and others in the case without radiation, which include collisional quenching, rotational energy transfer (RET), and vibrational energy transfer (VET). Based on these, some numerical results are achieved by simulations in order to evaluate the fluorescence yield at elevated pressure. These results are useful for understanding the real physical processes in OH-LIF technique and finding a way to calibrate the signal for quantitative measurement of OH concentration in a practical combustor. Project supported by the National Natural Science Foundation of China (Grant No. 11272338) and the Fund from the Science and Technology on Scramjet Key Laboratory, China (Grant No. STSKFKT2013004).

  5. Temporal scaling law and intrinsic characteristic of laser induced damage on the dielectric coating

    Science.gov (United States)

    Zhou, Li; Jiang, Youen; Wang, Chao; Wei, Hui; Zhang, Peng; Fan, Wei; Li, Xuechun

    2018-01-01

    High power laser is essential for optical manipulation and fabrication. When the laser travels through optics and to the target finally, irreversible damage on the dielectric coating is always accompanied without knowing the law and principle of laser induced damage. Here, an experimental study of laser induced damage threshold (LIDT) Fth of the dielectric coating under different pulse duration t is implemented. We observe that the temporal scaling law of square pulse for high-reflectivity (HR) coating and anti-reflectivity (AR) coating are Fth = 9.53t0.47 and Fth = 6.43t0.28 at 1064 nm, respectively. Moreover, the intrinsic LIDT of HR coating is 62.7 J/cm2 where the coating is just 100% damaged by gradually increasing the fluence densities of a 5ns-duration pulse, which is much higher than the actual LIDT of 18.6 J/cm2. Thus, a more robust and reliable high power laser system will be a reality, even working at very high fluence, if measures are taken to improve the actual LIDT to a considerable level near the intrinsic value.

  6. Effects of ambient conditions on femtosecond laser-induced breakdown spectroscopy of Al

    Science.gov (United States)

    Nakimana, Agnes; Tao, Haiyan; Gao, Xun; Hao, Zuoqiang; Lin, Jingquan

    2013-07-01

    Aluminum alloy was analysed by using femtosecond laser-induced breakdown spectroscopy under argon, air and helium environments at pressures ranging from 1 to 80 kPa. The results reveal that both spectra intensity and lines detection are significantly influenced by the ambient conditions. In all ambient gases, as the pressure increases the emitted light initially increases, attains its maximum intensity and then decreases with further increase in pressure. It is also observed that some lines are well detected at low pressures in argon while they are absent at the same pressures in helium. In addition, plasma parameters such as electron densities and electron temperature have been investigated at different pressures in the three gases. Hotter and denser plasma has been observed in argon than that in air and helium. Furthermore, it is noted that plasma parameters at relative low pressures of argon (1 kPa) are similar to those obtained at relative high pressures of helium (80 kPa). The optimum conditions for the use of argon and helium as ambient gases have been determined. In fact, argon provides the best environment of femtosecond laser-induced breakdown spectroscopy only at relative low pressures while helium constitutes a good environment only at relative high pressures.

  7. Tomography of homogenized laser-induced plasma by Radon transform technique

    Science.gov (United States)

    Eschlböck-Fuchs, S.; Demidov, A.; Gornushkin, I. B.; Schmid, T.; Rössler, R.; Huber, N.; Panne, U.; Pedarnig, J. D.

    2016-09-01

    Tomography of a laser-induced plasma in air is performed by inverse Radon transform of angle-resolved plasma images. Plasmas were induced by single laser pulses (SP), double pulses (DP) in collinear geometry, and by a combination of single laser pulses with pulsed arc discharges (SP-AD). Images of plasmas on metallurgical steel slags were taken at delay times suitable for calibration-free laser-induced breakdown spectroscopy (CF-LIBS). Delays ranged from few microseconds for SP and DP up to tens of microseconds for SP-AD excitation. The white-light and the spectrally resolved emissivity ε(x,y,z) was reconstructed for the three plasma excitation schemes. The electron number density Ne(x,y,z) and plasma temperature Te(x,y,z) were determined from Mg and Mn emission lines in reconstructed spectra employing the Saha-Boltzmann plot method. The SP plasma revealed strongly inhomogeneous emissivity and plasma temperature. Re-excitation of plasma by a second laser pulse (DP) and by an arc discharge (SP-AD) homogenized the plasma and reduced the spatial variation of ε and Te. The homogenization of a plasma is a promising approach to increase the accuracy of calibration-free LIBS analysis of complex materials.

  8. Femtosecond laser-induced breakdown spectroscopy: Elemental imaging of thin films with high spatial resolution

    Science.gov (United States)

    Ahamer, Christoph M.; Riepl, Kevin M.; Huber, Norbert; Pedarnig, Johannes D.

    2017-10-01

    We investigate femtosecond laser-induced breakdown spectroscopy (fs-LIBS) for the spectrochemical imaging of thin films with high spatial resolution. Chemical images are obtained by recording LIBS spectra at each site of 2D raster-scans across the samples employing one fs-laser pulse per site. The diffraction images of the Echelle spectrometer are binned to reduce the read-out time of the intensified CCD detector and to increase the stability of the emission signals against peak drifts in the echellograms. For copper thin films on glass the intensities of Cu I emission lines and the size of ablation craters vary non-monotonously with the film thickness hCu = 5-500 nm. The emission efficiency, defined as the Cu I line intensity per ablated volume, strongly decreases for films thicker than the optical penetration depth. The Na I line intensity from glass increases exponentially with decreasing Cu film thickness. For yttrium barium copper oxide (YBCO) thin films on MgO various atomic and molecular emission lines of the laser-induced plasma are measured (film thickness hYBCO = 200-1000 nm). The obtained element (Y, Ba, Cu, Mg) and molecular (Y-O) fs-LIBS images match the structure of the micro-patterned YBCO films very well. The achieved lateral resolution δr = 6 μm is among the best values reported for spectrochemical LIBS imaging.

  9. Femtosecond-laser-induced damage initiation mechanism on metal multilayer dielectric gratings for pulse compression

    Science.gov (United States)

    Huang, Haopeng; Kong, Fanyu; Xia, Zhilin; Jin, Yunxia; Li, Linxin; Wang, Leilei; Chen, Junming; Cui, Yun; Shao, Jianda

    2018-01-01

    The femtosecond-laser-induced damage behaviors of metal multilayer dielectric gratings (MMDG) for pulse compression are explored. The grating ridge of this type of MMDG consists of a layer of HfO2 sandwiched between two SiO2 layers. The initial damage position is on the HfO2 layer of the ridge which opposite to the laser beam direction. A theoretical model is constructed to explain the femtosecond-laser-induced damage initiation mechanism on the MMDG, and the model can simulate the evolution of the electron density in the conduction band and the change of the dielectric constants of HfO2 and SiO2 in the sandwiched grating structure. The dramatic increase in the imaginary part of the dielectric constant of the middle HfO2 layer indicates that it strongly absorbs laser energy, resulting in damage to the MMDG. The experimental results and theoretical calculation agree very well with each other.

  10. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    Science.gov (United States)

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A.; Belasri, A.

    2015-09-01

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C CF-LIBS calculated by CF-LIBS and the certified concentrations C certified were very close.

  11. Geographical analysis of 'conflict minerals' utilizing laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hark, Richard R., E-mail: hark@juniata.edu [Department of Chemistry, Juniata College, Huntingdon, PA 16652 (United States); Remus, Jeremiah J. [Department of Electrical and Computer Engineering, Clarkson University, Potsdam, NY 13699 (United States); East, Lucille J. [Applied Spectra, Inc., Fremont, CA 94538 (United States); Harmon, Russell S. [Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695 (United States); Wise, Michael A. [Department of Mineral Sciences, Smithsonian Institution, Washington, DC 20013 (United States); Tansi, Benjamin M.; Shughrue, Katrina M. [Department of Chemistry, Juniata College, Huntingdon, PA 16652 (United States); Dunsin, Kehinde S. [Department of Electrical and Computer Engineering, Clarkson University, Potsdam, NY 13699 (United States); Liu, Chunyi [Applied Spectra, Inc., Fremont, CA 94538 (United States)

    2012-08-15

    Laser-induced breakdown spectroscopy (LIBS) offers a means of rapidly distinguishing different geographic sources for a mineral because the LIBS plasma emission spectrum provides information on the chemical composition (i.e. geochemical fingerprint) of a geomaterial. An application of this approach with potentially significant commercial and political importance is the spectral fingerprinting of 'conflict minerals' such as columbite-tantalite ('coltan'). Following a successful pilot study of a columbite-tantalite suite from North America, a more geographically diverse set of 57 samples from 37 locations around the world was analyzed using a commercially available LIBS system. The LIBS spectra were analyzed using advanced multivariate statistical signal processing techniques. Partial least squares discriminant analysis (PLSDA) resulted in a correct place-level geographic classification at success rates above 90%. The possible role of rare-earth elements (REEs) as a factor contributing to the high levels of sample discrimination was explored. These results provide additional evidence that LIBS has the potential to be utilized in the field as a real-time screening tool to discriminate between columbite-tantalite ores of different provenance. - Highlights: Black-Right-Pointing-Pointer Analysis of columbite-tantalite using laser-induced breakdown spectroscopy (LIBS) Black-Right-Pointing-Pointer Chemometric analysis (PLSDA) affords 90-100% correct sample classification. Black-Right-Pointing-Pointer Possible role of rare-earth elements in the high level of sample discrimination.

  12. A theoretical analysis for temperature dependences of laser-induced damage threshold

    Science.gov (United States)

    Mikami, K.; Motokoshi, S.; Somekawa, T.; Jitsuno, T.; Fujita, M.; Tanaka, K. A.

    2013-11-01

    The temperature dependence of the laser-induced damage threshold on optical coatings was studied in detail for laser pulses from 123 K to 473 K at different temperature using Nd:YAG laser (wavelength 1064 nm and pulse width 4 ns) and Ti:Sapphire laser (wavelength 800 nm and pulse width 100 fs, 2 ps, and 200 ps). The six kinds of optical monolayer coatings were prepared by electron beam evaporation and the coating materials were SiO2, Al2O3, HfO2, ZrO2, Ta2O5, and MgF2. For pulses longer than a few picoseconds, the laser-induced damage threshold of single-layer coatings increased with decreasing temperature. This temperature dependence was reversed for pulses shorter than a few picoseconds. We describe the physics models to explain the observed scaling. The electron avalanche is essential to explain the differences in the temperature dependence. In other words, the balance between linear process such as electron avalanche etc. and nonlinear process such as multiphoton ionization etc. will be able to decide the tendency of the temperature dependence. The proposed model also gives one of possibility for an extremely high LIDT optics.

  13. Laser-induced damage of multilayer dielectric for broadband pulse compression grating

    Science.gov (United States)

    Kong, Fanyu; Chen, Shunli; Liu, Shijie; Jin, Yunxia; Guan, Heyuan; Du, Ying; Wei, Chaoyang; He, Hongbo; Yi, Kui

    2012-01-01

    The multilayer dielectrics (MLDs) for broad bandwidth 800nm pulse compression gratings were fabricated with optimized design by electron beam evaporation using three different kinds of materials (Ta2O5/SiO2/HfO2), which had more than 99% reflectance with bandwidth larger than 160nm around the center wavelength of 800 nm and high transmission at the exposure wavelength of 413nm. Laser-induced damage behaviors of the mirrors were investigated. It was found that the laser-induced damage threshold (LIDT) of the samples could reach 1.0J/cm2 and 2.0J/cm2 in the normal beam (57 degrees, TE mode) at pulse duration of 50fs and 120fs, respectively. The depth information of the damage sites at these two cases was explored by atomic force microscope (AFM). The reason of the sample having so high LIDT was also discussed in this paper. The MLDs provide a solid base for the high laser threshold 800nm pulse compression gratings and may open a new way for broad bandwidth 800nm reflectance coatings used in the ultrashort pulse laser system.

  14. Multivariate methods for analysis of environmental reference materials using laser-induced breakdown spectroscopy

    Directory of Open Access Journals (Sweden)

    Shikha Awasthi

    2017-06-01

    Full Text Available Analysis of emission from laser-induced plasma has a unique capability for quantifying the major and minor elements present in any type of samples under optimal analysis conditions. Chemometric techniques are very effective and reliable tools for quantification of multiple components in complex matrices. The feasibility of laser-induced breakdown spectroscopy (LIBS in combination with multivariate analysis was investigated for the analysis of environmental reference materials (RMs. In the present work, different (Certified/Standard Reference Materials of soil and plant origin were analyzed using LIBS and the presence of Al, Ca, Mg, Fe, K, Mn and Si were identified in the LIBS spectra of these materials. Multivariate statistical methods (Partial Least Square Regression and Partial Least Square Discriminant Analysis were employed for quantitative analysis of the constituent elements using the LIBS spectral data. Calibration models were used to predict the concentrations of the different elements of test samples and subsequently, the concentrations were compared with certified concentrations to check the authenticity of models. The non-destructive analytical method namely Instrumental Neutron Activation Analysis (INAA using high flux reactor neutrons and high resolution gamma-ray spectrometry was also used for intercomparison of results of two RMs by LIBS.

  15. Laser-induced breakdown spectroscopy measurements of uranium and thorium powders and uranium ore

    Energy Technology Data Exchange (ETDEWEB)

    Judge, Elizabeth J. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Barefield, James E., E-mail: jbarefield@lanl.gov [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Berg, John M. [Manufacturing Engineering and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Clegg, Samuel M.; Havrilla, George J.; Montoya, Velma M.; Le, Loan A.; Lopez, Leon N. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-05-01

    Laser-induced breakdown spectroscopy (LIBS) was used to analyze depleted uranium and thorium oxide powders and uranium ore as a potential rapid in situ analysis technique in nuclear production facilities, environmental sampling, and in-field forensic applications. Material such as pressed pellets and metals, has been extensively studied using LIBS due to the high density of the material and more stable laser-induced plasma formation. Powders, on the other hand, are difficult to analyze using LIBS since ejection and removal of the powder occur in the laser interaction region. The capability of analyzing powders is important in allowing for rapid analysis of suspicious materials, environmental samples, or trace contamination on surfaces since it most closely represents field samples (soil, small particles, debris etc.). The rapid, in situ analysis of samples, including nuclear materials, also reduces costs in sample collection, transportation, sample preparation, and analysis time. Here we demonstrate the detection of actinides in oxide powders and within a uranium ore sample as both pressed pellets and powders on carbon adhesive discs for spectral comparison. The acquired LIBS spectra for both forms of the samples differ in overall intensity but yield a similar distribution of atomic emission spectral lines. - Highlights: • LIBS analysis of mixed actinide samples: depleted uranium oxide and thorium oxide • LIBS analysis of actinide samples in powder form on carbon adhesive discs • Detection of uranium in a complex matrix (uranium ore) as a precursor to analyzing uranium in environmental samples.

  16. Laser-induced deformation of triatomic molecules: Influence on tunnel ionization

    Science.gov (United States)

    Kornev, Aleksei S.; Chernov, Vladislav E.; Zon, Boris A.

    2017-11-01

    We consider a type of light-dressing effect in molecules which is due to laser-induced deformation of molecules. We derive general formulas which describe the change of the equilibrium bond lengths, bending angles, and vibration frequencies for a polyatomic molecule. Up to the second-order terms in the field strength, the normal coordinates of the molecule are not changed. Explicit expressions for the change of the geometric parameters and vibration frequencies are found for a nonlinear triatomic molecule of the A2B type. These results are applied to calculation of the tunnel-ionization rates for H2O , H2O+ , and SO2 molecules, both in ac and dc fields. The main influence of the laser-induced deformation on the tunnel ionization is due to the changes in Franck-Condon factors, which are determined by overlap of the nuclei wave function of the molecule and its residual ion. In a laser field with an intensity of ˜1014W /cm2 , the contribution of the laser-dressing effect to the ionization rate is within 5% for H2O and H2O+ , while accounting for this effect changes the ionization rate of the SO2 molecule by up to 20 times depending on the molecule's orientation with respect to the electric-field vector. Such a large difference is due to the electronic structures of these molecules.

  17. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A., E-mail: sidahmed.beldjilali@univ-usto.dz; Belasri, A. [Université des Sciences et de la Technologie d’Oran Mohamed Boudiaf USTO-MB, LPPMCA (Algeria)

    2015-09-15

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C{sub CF-LIBS} calculated by CF-LIBS and the certified concentrations C{sub certified} were very close.

  18. A comparative study on laser induced shock cleaning of radioactive contaminants in air and water

    Science.gov (United States)

    Kumar, Aniruddha; Prasad, Manisha; Bhatt, R. B.; Behere, P. G.; Biswas, D. J.

    2018-03-01

    Efficient removal of Uranium-di-oxide (UO2) particulates from stainless steel surface was effected by Nd-YAG laser induced plasma shock waves in air as well as in water environment. The propagation velocity of the generated shock wave was measured by employing the photo-acoustic probe deflection method. Monitoring of the alpha activity of the sample with a ZnS (Ag) scintillation detector before and after the laser exposure allowed the estimation of decontamination efficiency defined as the percentage removal of the initial activity. Experiments were carried out to study the effect of laser pulse energy, number of laser exposures, orientation of the sample, the separation between the substrate surface and the onset point of the shock wave on the de-contamination efficiency. The most optimised cleaning was found to occur when the laser beam impinged normally on the sample that was immersed in water and placed at a distance of ∼0.7 mm from the laser focal spot. Analysis of the cleaned surface by optical microscopes established that laser induced shock cleaning in no way altered the surface property. The shock force generated in both air and water has been estimated theoretically and has been found to exceed the Van der Waal's binding force for spherical contaminant particulate.

  19. Elemental analysis of steel scrap metals and minerals by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vieitez, Maria Ofelia [Department of Physics, Royal Institute of Technology, AlbaNova University Centrum, SE-10691 Stockholm (Sweden); Hedberg, Jonas [Department of Physics, Royal Institute of Technology, AlbaNova University Centrum, SE-10691 Stockholm (Sweden); Launila, Olli [Department of Physics, Royal Institute of Technology, AlbaNova University Centrum, SE-10691 Stockholm (Sweden)]. E-mail: olli@physics.kth.se; Berg, Lars-Erik [Department of Physics, Royal Institute of Technology, AlbaNova University Centrum, SE-10691 Stockholm (Sweden)

    2005-08-31

    The atomic emission of laser-induced plasma on steel samples has been studied for quantitative elemental analysis. The plasma has been created with 8 ns wide pulses using the second-harmonic from a Q-switched Nd:YAG laser, in air at atmospheric pressure. The plasma emission is detected with temporal resolution, using an Echelle spectrometer of wide spectral range (300-900 nm) combined with an intensified charge coupled device camera. A plasma temperature of 7800 {+-} 400 K is determined using the Boltzmann plot method, from spectra obtained under optimized experimental conditions. As an example of an industrial application the concentration of copper in scrap metals is studied, which is an important factor to determine the quality of the samples to recycle. Cu concentrations down to 200 ppm can be detected. Another application of the laser-induced plasma spectroscopy method is the measurement of the nickel and copper concentrations in an iron-containing sample of reduced magma from the 1870s expedition to western Greenland by Adolf Erik Nordenskioeld. Different spectral lines of nickel are used for calibration, and their results are compared.

  20. Application of laser-induced breakdown spectroscopy to the analysis of algal biomass for industrial biotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Porizka, P.; Prochazka, D. [X-ray micro CT and nano CT research group, CEITEC-Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, 616 00 Brno (Czech Republic); Pilat, Z. [Institute of Scientific Instruments of the ASCR v.v.i., Academy of Sciences of the Czech Republic, Kralovopolska 147, Brno 61669 (Czech Republic); Krajcarova, L. [Department of Chemistry, Faculty of Sciences, Masaryk University, Kotlarska 2, Brno 611 37 (Czech Republic); Kaiser, J., E-mail: kaiser@fme.vutbr.cz [X-ray micro CT and nano CT research group, CEITEC-Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, 616 00 Brno (Czech Republic); Malina, R.; Novotny, J. [X-ray micro CT and nano CT research group, CEITEC-Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, 616 00 Brno (Czech Republic); Zemanek, P.; Jezek, J.; Sery, M.; Bernatova, S.; Krzyzanek, V.; Dobranska, K. [Institute of Scientific Instruments of the ASCR v.v.i., Academy of Sciences of the Czech Republic, Kralovopolska 147, Brno 61669 (Czech Republic); Novotny, K. [Department of Chemistry, Faculty of Sciences, Masaryk University, Kotlarska 2, Brno 611 37 (Czech Republic); Trtilek, M. [Photon Systems Instruments, Drasov 470, 664 24 Drasov (Czech Republic); Samek, O. [Institute of Scientific Instruments of the ASCR v.v.i., Academy of Sciences of the Czech Republic, Kralovopolska 147, Brno 61669 (Czech Republic)

    2012-08-15

    We report on the application of laser-induced breakdown spectroscopy (LIBS) to the determination of elements distinctive in terms of their biological significance (such as potassium, magnesium, calcium, and sodium) and to the monitoring of accumulation of potentially toxic heavy metal ions in living microorganisms (algae), in order to trace e.g. the influence of environmental exposure and other cultivation and biological factors having an impact on them. Algae cells were suspended in liquid media or presented in a form of adherent cell mass on a surface (biofilm) and, consequently, characterized using their spectra. In our feasibility study we used three different experimental arrangements employing double-pulse LIBS technique in order to improve on analytical selectivity and sensitivity for potential industrial biotechnology applications, e.g. for monitoring of mass production of commercial biofuels, utilization in the food industry and control of the removal of heavy metal ions from industrial waste waters. - Highlights: Black-Right-Pointing-Pointer We realized laser-induced breakdown spectroscopy (LIBS) analysis of algal biomass. Black-Right-Pointing-Pointer We used water jet setup, bulk liquid arrangement and algal biofilms. Black-Right-Pointing-Pointer LIBS analysis of macro- and micro-element concentrations in algae was shown. Black-Right-Pointing-Pointer LIBS can be of assistance in research of sustainable biofuel generation. Black-Right-Pointing-Pointer LIBS can be used in research of algal food applications and bioremediation.

  1. Development of Laser-induced Grating Spectroscopy for Underwater Temperature Measurement in Shock Wave Focusing Regions

    Science.gov (United States)

    Gojani, Ardian B.; Danehy, Paul M.; Alderfer, David W.; Saito, Tsutomu; Takayama, Kazuyoshi

    2003-01-01

    In Extracorporeal Shock Wave Lithotripsy (ESWL) underwater shock wave focusing generates high pressures at very short duration of time inside human body. However, it is not yet clear how high temperatures are enhanced at the spot where a shock wave is focused. The estimation of such dynamic temperature enhancements is critical for the evaluation of tissue damages upon shock loading. For this purpose in the Interdisciplinary Shock Wave Research Center a technique is developed which employs laser induced thermal acoustics or Laser Induced Grating Spectroscopy. Unlike most of gasdynamic methods of measuring physical quantities this provides a non-invasive one having spatial and temporal resolutions of the order of magnitude of 1.0 mm3 and 400 ns, respectively. Preliminary experiments in still water demonstrated that this method detected sound speed and hence temperature in water ranging 283 K to 333 K with errors of 0.5%. These results may be used to empirically establish the equation of states of water, gelatin or agar cells which will work as alternatives of human tissues.

  2. Laser-induced dry-fabrication of bibenzyl molecular layers on the silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yong Ping, E-mail: zhangyyping@yahoo.com [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Chen, Zhi Qian [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Dong, Dong [School of Materials Science and Engineering, Northwest Polytechnical University, Xi’an 710072 (China); Xu, Guo Qin, E-mail: chmxugq@nus.edu.sg [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore)

    2014-08-30

    Graphical abstract: Schematic illustration of photoinduced polymerization of 4-bromostyrene molecules on the Si(1 1 1)-(7 × 7) surface. - Highlights: • Laser-induced fabrication of molecular layer. • XPS and HREELS experimental evidence for the reaction. • DFT explanation of photochemical reaction. - Abstract: The covalently attached organic monolayer has great effects on the structures of the organic semiconductor thin films and their electronic transport properties in the fabrication of molecular electronic devices. A laser-induced dry-fabrication method has been developed to form bibenzyl-like molecular layers by photoinduced reaction of 4-bromostyrene molecules on silicon surface in the vacuum environment. The radical site produced via the C–Br bond cleavage concurrently reacts with the C=C vinyl group of the physisorbed 4-bromostyrene molecule above to form the –CH{sub 2}–CHBr– covalent linkage. X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS) experimental results and density functional theory (DFT) calculations confirm the formation of covalently bonded bibenzyl-like (Phi–CH{sub 2}–CHBr–Phi) molecular layers on the silicon surface.

  3. Laser-Induced Breakdown Spectroscopy and Plasma Characterization Generated by Long-Pulse Laser on Soil Samples

    Science.gov (United States)

    Xu, S.; Duan, W.; Ning, R.; Li, Q.; Jiang, R.

    2017-03-01

    The plasma is generated by focusing a long-pulse (80 μs) Nd:YAG laser on chromium-doped soil samples. The calibration curves are drawn using the intensity ratio of the chromium spectral line at 425.435 nm with the iron spectral line (425.079 nm) as reference. The regression coefficient of the calibration curve is 0.993, and the limit of detection is 16 mg/kg, which is 19% less than that for the case of a Q-switched laser In the method of long-pulse laser-induced breakdown spectroscopy, the laser-induced plasma had a temperature of 15795.907 K and an electron density of 2.988 × 1017 cm-3, which exceeded the corresponding plasma parameters of the Q-switched laser-induced breakdown spectroscopy by 75% and 24% respectively.

  4. The potential of laser-induced breakdown spectrometry for real time monitoring the laser cleaning of archaeometallurgical objects

    Science.gov (United States)

    Fortes, F. J.; Cabalín, L. M.; Laserna, J. J.

    2008-10-01

    In this work, an orthogonal double pulse (DP) laser-induced breakdown spectroscopy configuration as a diagnostic tool for the restoration of archaeometallurgical samples has been developed and evaluated. Although laser-induced breakdown spectroscopy has been extensively tested in this kind of applications, this study presents an alternative method in terms of controlling the laser cleaning process of metallic object as well as real time laser-induced breakdown spectroscopy monitoring of the emission signal of the ablated material (pollutants and the structural materials). Several experimental parameters such as interpulses delay time, second laser to target distance and second pulse energy delay have also been accomplished in ancient Alexandrian coins. An enhancement of the signal emission is observed when both cleaning and analyzing lasers are combined, while no spectra signal is achieved when both lasers are operating independently. The restoration of ancient object by means of both conventional and double pulse laser cleaning arrangements is also discussed.

  5. The potential of laser-induced breakdown spectrometry for real time monitoring the laser cleaning of archaeometallurgical objects

    Energy Technology Data Exchange (ETDEWEB)

    Fortes, F.J.; Cabalin, L.M. [Department of Analytical Chemistry, Faculty of Sciences, University of Malaga, Campus de Teatinos s/n, 29071 Malaga (Spain); Laserna, J.J. [Department of Analytical Chemistry, Faculty of Sciences, University of Malaga, Campus de Teatinos s/n, 29071 Malaga (Spain)], E-mail: laserna@uma.es

    2008-10-15

    In this work, an orthogonal double pulse (DP) laser-induced breakdown spectroscopy configuration as a diagnostic tool for the restoration of archaeometallurgical samples has been developed and evaluated. Although laser-induced breakdown spectroscopy has been extensively tested in this kind of applications, this study presents an alternative method in terms of controlling the laser cleaning process of metallic object as well as real time laser-induced breakdown spectroscopy monitoring of the emission signal of the ablated material (pollutants and the structural materials). Several experimental parameters such as interpulses delay time, second laser to target distance and second pulse energy delay have also been accomplished in ancient Alexandrian coins. An enhancement of the signal emission is observed when both cleaning and analyzing lasers are combined, while no spectra signal is achieved when both lasers are operating independently. The restoration of ancient object by means of both conventional and double pulse laser cleaning arrangements is also discussed.

  6. Real-time in vivo micromorphology and histopathology of choroidal osteoma using enhanced depth imaging

    Directory of Open Access Journals (Sweden)

    Rameez Hussain

    2015-01-01

    Full Text Available Choroidal osteoma is a usually unilateral benign tumor of the choroid composed of mature bone. Optical coherence tomography (OCT has been used to image osteoma for several years. With the advent of enhanced depth imaging (EDI feature of spectral-domain OCT (SD-OCT, better visualization of the morphology of choroidal lesions has been possible. Herein we present a case of choroidal osteoma in a 45-year-old woman, wherein in vivo morphology of the choroidal osteoma had been visualized using EDI technique of SD-OCT before and after performing photodynamic therapy. EDI OCT has proven to be a valuable noninvasive imaging modality, almost comparable to histopathological examination, for diagnosing choroidal osteomas and for providing an insight into the in vivo micromorphological changes occurring during the course of the disease.

  7. A choroid plexus cyst in the fourth ventricle of a Sprague-Dawley rat.

    Science.gov (United States)

    Murai, Atsuko; Nakamura, Kenji; Takimoto, Norifumi; Namiki, Kengo; Hibi, Daisuke; Yanagizawa, Yukihiro; Shimouchi, Koji

    2017-07-01

    Choroid plexus cysts are rare lesions in the brain and are reported in humans and dogs. Herein, we report a choroid plexus cyst found in a 10-week-old female Sprague-Dawley rat. Histologically, a cyst measuring approximately 600 μm in diameter was found in the fourth ventricle of the brain. The cyst was lined with a single layer of flattened cells and was present in the connective tissue of the choroid plexus. Next to the cyst, a dilated tube was found with a similar morphology to the epithelium of the choroid plexus. Immunohistochemistry revealed that flattened cells lining the cyst were positive for cytokeratin and vimentin, and negative for GFAP and S-100, which is the same as in the normal choroid plexus, excluding vimentin. We diagnosed the present cyst as a spontaneously occurring choroid plexus cyst that was considered to be undergoing the epithelial-mesenchymal transition.

  8. Complete Disappearance of Choroidal Metastasis from Lung Adenocarcinoma Treated with Bevacizumab and Chemotherapy

    Directory of Open Access Journals (Sweden)

    Hampig Raphael Kourie

    2015-01-01

    Full Text Available Choroidal metastasis from lung cancer is uncommon. We report a case of choroidal metastasis as an inaugural manifestation of lung adenocarcinoma, successfully treated by docetaxel, cisplatinum, and intravenous bevacizumab as an antiangiogenesis therapy. A complete remission was obtained after 4 cycles and maintained after six cycles. This case report demonstrates the importance of the systemic bevacizumab and chemotherapy in the treatment of choroidal metastasis from adenocarcinoma of the lung.

  9. A CASE OF FULL-THICKNESS MACULAR HOLE IN EYE WITH FOCAL CHOROIDAL EXCAVATION.

    Science.gov (United States)

    Fayyad, Omar Faisal; Al-Hashimi, Mustafa Raad; Fayyad, Faisal Tawfeeq

    2016-12-09

    To report an association between a Stage 4 full-thickness macular hole and focal choroidal excavation. Case report. A 46-year-old male patient with high myopia was referred for macular hole surgery and found to have an associated focal choroidal excavation. The patient underwent uneventful combined procedure with closure of macular hole. Successful macular hole surgery can be achieved even in the presence of focal choroidal excavation.

  10. Evaluation of focal choroidal excavation in the macula using swept-source optical coherence tomography.

    Science.gov (United States)

    Lim, F P M; Loh, B K; Cheung, C M G; Lim, L S; Chan, C M; Wong, D W K

    2014-09-01

    To evaluate imaging findings of patients with focal choroidal excavation (FCE) in the macula using swept-source optical coherence tomography (SS-OCT) and correlate it clinically. Prospective observational case series. Eleven consecutive patients (12 eyes) with FCE were described. Data on demographics and clinical presentation were collected and imaging findings (including color photography, fundus autofluorescence imaging, fluorescein angiography, indocyanine green angiography, spectral-domain optical coherence tomography, and SS-OCT) were analyzed. The primary diagnosis was epiretinal membrane (two eyes), choroidal neovascularization (one eye), polypoidal choroidal vasculopathy (three eyes), central serous chorioretinopathy (one eye), and dry age-related macular degeneration (two eyes). Eleven out of 12 of the lesions were conforming. One presented with a non-conforming lesion that progressed to a conforming lesion. One eye had multiFCE and two had two overlapping choroidal excavations. Using the SS-OCT, we found the choroid to be thinned out at the area of FCE but sclera remained normal. The choroidal tissue beneath the FCE was abnormal, with high internal reflectivity and poor visualization of choroidal vessels. There was loss of contour of the outer choroidal boundary that appeared to be pulled inward by this abnormal choroidal tissue. A suprachoroidal space was noted beneath this choroidal tissue and the choroidal-scleral interface was smooth. Repeat SS-OCT 6 months after presentation showed the area of excavation to be stable in size. FCE can be associated with epiretinal membrane, central serous chorioretinopathy, and age-related macular degeneration. The choroid was thinned out in the area of FCE.

  11. CAVERNOUS HEMANGIOMALIKE CHANGES IN A CHOROIDAL MELANOMA AFTER BRACHYTHERAPY.

    Science.gov (United States)

    Lopez, Michael; Johnson, Jean G; Margo, Curtis E; Pavan, Peter R

    2016-01-01

    To describe a degenerative vascular change in a treated choroidal melanoma that clinically simulated late treatment failure. Observational case report. A 79-year-old man with choroidal melanoma treated 15 years earlier with iodine-125 brachytherapy demonstrated substantial increase in size of this once stable tumor. The eye was removed because of concern of late treatment failure. Histologically, the tumor consisted of melanocytes with no mitotic activity and virtually no Ki-67 expression. Roughly half the lesion was composed of cavernous blood-filled spaces lined by bland CD34+ and CD31+ endothelial cells. Late degenerative changes in the vasculature of treated uveal melanoma can result in tumor enlargement, which may raise clinical concerns over treatment failure and neoplastic potential.

  12. Current and emerging treatment options for myopic choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    El Matri L

    2015-04-01

    Full Text Available Leila El Matri, Ahmed Chebil, Fedra Kort Department B of Ophthalmology, Hedi Rais Institute of Ophthalmology, Faculty of Medicine of Tunis, University of El Manar, Tunis, Tunisia Abstract: Choroidal neovascularization (CNV is the main cause of visual impairment in highly myopic patients younger than 50 years of age. There are different treatments for myopic CNV (mCNV, with 5- to 10-year outcomes currently. Chorioretinal atrophy is still the most important determinant factor for visual outcome. The purpose of this study is to provide an overview of the current treatments for mCNV, including laser, surgical management, verteporfin photodynamic therapy, and mainly anti-vascular endothelial growth factor therapy. Emerging treatment options are also discussed. Keywords: myopia, choroidal neovascularization, current treatment, emerging treatment

  13. [Intravitreal bevacizumab for choroidal neovascularization associated with Best's disease].

    Science.gov (United States)

    Velazquez-Villoria, D; Macià Badia, C; Rigo Quera, J; Velez-Escola, L; Arcos-Algaba, G; Martínez-Castillo, V; García-Arumí, J

    2014-10-01

    A 27-year old woman presented with loss of vision in the right eye (20/200). Ophthalmoscopic examination showed intrarretinal hemorrhage in the macular region with neurosensory detachment in the right eye, and viteliform deposit on the left eye. Fluorescein angiography and the electrooculogram confirmed the diagnosis of choroidal neovascularization associated with Best's disease. Four weeks after a single bevacizumab intravitreal injection, visual acuity was restored (20/25) and remained stable after a 12 month follow-up. Intravitreal bevacizumab appears to be an effective treatment for choroidal neovascularization associated to Best's disease. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  14. Transcriptome of the human retina, retinal pigmented epithelium and choroid

    Science.gov (United States)

    Tian, Lifeng; Kazmierkiewicz, Krista L; Bowman, Anita S; Li, Mingyao; Curcio, Christine A; Stambolian, Dwight E

    2015-01-01

    The retina and its adjacent supporting tissues -- retinal pigmented epithelium (RPE) and choroid -- are critical structures in human eyes required for normal visual perception. Abnormal changes in these layers have been implicated in diseases such as age-related macular degeneration and glaucoma. With the advent of high-throughput methods, such as serial analysis of gene expression, cDNA microarray, and RNA sequencing, there is unprecedented opportunity to facilitate our understanding of the normal retina, RPE, and choroid. This information can be used to identify dysfunction in age-related macular degeneration and glaucoma. In this review, we describe the current status in our understanding of these transcriptomes through the use of high throughput techniques. PMID:25645700

  15. Laser-induced ignition and combustion in a SI engine with direct injection; Laserzuendung und Verbrennung im Ottomotor mit Direkteinspritzung

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Volker; Kubach, Heiko; Spicher, Ulrich [Karlsruher Institut fuer Technologie, Karlsruhe (Germany). Inst. fuer Kolbenmaschinen; Schiessl, Robert; Maas, Ulrich [Karlsruher Institut fuer Technologie, Karlsruhe (Germany). Inst. fuer Technische Thermodynamik

    2010-07-15

    Laser-induced ignition has shown huge advantages for the combustion of lean air- fuel mixtures in SI engines. A research project founded by the FVV under 'DI Laserzuendung' and No. 928 was set up at the Institute for Reciprocating Engines (IFKM) and the Institute for Technical Thermodynamics (ITT) at the Karlsruhe Institute of Technology (KIT) to investigate the potential of the laser-induced ignition. The emphasis was on improving combustion initiation and heat release during a direct injection with a spray-guided combustion. (orig.)

  16. Combination of Nd:Yag laser-induced subconjunctival bleeding and intracameral viscoelastic injection to treat hypotony maculopathy.

    Science.gov (United States)

    Ascaso, F J; Loras, E; Cristobal, J A

    2002-01-01

    A 38-year-old man with primary open-angle glaucoma who had undergone trabeculectomy with mitomycin-C developed macular folds consistent with hypotony maculopathy. The patient was successfully treated with a combination of Neodymium:yttrium-aluminum-garnet (Nd:YAG) laser-induced subconjunctival bleeding and injection of a viscoelastic substance into the anterior chamber. The combination of Nd:YAG laser-induced subconjunctival bleeding with intracameral viscoelastic injection appears to be a reasonable alternative to autologous blood injection and may be tried as first-line treatment for hypotony maculopathy caused by overfiltration.

  17. Temperature measurements of micro-droplets using pulsed 2-color laser-induced fluorescence with MDR-enhanced energy transfer

    Science.gov (United States)

    Palmer, Johannes; Reddemann, Manuel A.; Kirsch, Valeri; Kneer, Reinhold

    2016-12-01

    In this work, a new measurement system is presented for studying temperature of micro-droplets by pulsed 2-color laser-induced fluorescence. Pulsed fluorescence excitation allows motion blur suppression and thus simultaneous measurements of droplet size, velocity and temperature. However, high excitation intensities of pulsed lasers lead to morphology-dependent resonances inside micro-droplets, which are accompanied by disruptive stimulated emission. Investigations showed that stimulated emission can be avoided by enhanced energy transfer via an additional dye. The suitability and accuracy of the new pulsed method are verified on the basis of a spectroscopic analysis and comparison to continuously excited 2-color laser-induced fluorescence.

  18. Secondary choroidal lymphoma in a child treated for Burkitt lymphoma.

    Science.gov (United States)

    Ramasubramanian, Aparna; Shields, Carol L; Longmire, Michelle; Hunt, David J

    2011-02-01

    A 9-year-old girl presented with a choroidal tumor 6 years after remission of Burkitt lymphoma with no evidence of systemic recurrence. The tumor regressed after plaque radiotherapy. The second tumor could have been related to previous chemotherapy, caused by Epstein-Barr virus infection, or the result of independent lymphoma cell growth. Copyright © 2011 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

  19. Photochemical Thrombosis Of Retinal And Choroidal Vessels Using Rose Bengal

    Science.gov (United States)

    Lewis, Mary Lou; Winward, Kirk; Watson, Brant D.; Hernandez, Eleut

    1989-09-01

    Rose bengal is an effective photosensitizing agent which interacts with argon green light to induce photochemical thrombosis of irradiated vessels. We used focal, low energy irradiation to occlude retinal and choroidal vessels in both albino and pigmented rabbits. Immediately after intravenous injection of rose bengal at concentrations of 10 and 20 mg/kg, irradiation was performed via a slit lamp-delivered argon green laser (514.5 nm) with the aid of fundus contact lens. In 11 eyes, arteries were treated with 50-100 interrupted bursts of 75u spot size at 0.2 sec and 40-100 mW (9 choroidal vessels, serous elevation of the retina, and disc neovascularization. In eight eyes choroidal vessels were irradiated with 10-20 mW, 15-60 sec, 500u spot size (31 choroidal vessels. There was minimal damage to surrounding tissue. Control eyes in all three groups irradiated utilizing the same parameters, but without rose bengal, demonstrated no evidence of thermal injury.

  20. Choroidal thickness in diabetic patients of Indian ethnicity

    Directory of Open Access Journals (Sweden)

    Aditya Sudhalkar

    2015-01-01

    Full Text Available Purpose: To evaluate choroidal thickness (CT change in various grades of diabetic retinopathy (DR in comparison to age-matched healthy subjects. Methods: This prospective observational study included 227 eyes of 125 subjects with diabetes (study group: 58 females and 197 eyes of 110 age-matched healthy subjects (control group: 66 females. Collected data included age, gender, duration of diabetes, glycemic control, comprehensive ocular examination, fundus photography, and CT measurement on spectral domain ocular coherence tomography using enhanced depth imaging. Results: Mean age in the study group was 57.0 ± 9.37 years (43–73 years. The mean age was 41.48 ± 5.43 years in the control group. Subjects with diabetes with (252.8 ± 55.6 microns and without (261.71 ± 51.8 microns retinopathy had significantly thinner choroids when compared to the control group (281.7 ± 47.7 microns; P = 0.032. Seventy-four of 227 eyes did not have any evidence of DR, 89 eyes had features of nonproliferative diabetic retinopathy (NPDR, and 33 eyes had treatment naïve proliferative diabetic retinopathy (PDR. Thirty-one PDR eyes had received previous laser photocoagulation. Subjects with diabetes without retinopathy had a greater subfoveal choroidal thickness (SFCT than subjects with diabetes with retinopathy (P < 0.001. Eyes with PDR (243.9 ± 56.2 microns had thinner SFCT than those with NPDR (238.98 ± 111.23 microns. There was no difference in the SFCT between treated (laser photocoagulation done; 251.784 ± 103.72 microns and treatment naïve PDR (258.405 ± 89.47 microns, P = 0.23. Conclusions: Control eyes had greater SFCT compared to subjects with diabetes, with and without retinopathy. The thinning progressed with increasing severity of DR. Choroidal thinning may contribute to DR pathogenesis.

  1. Silent polypoidal choroidal vasculopathy in a patient with angioid streaks

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    Zafer Cebeci

    2016-06-01

    Full Text Available ABSTRACT We present a case of silent polypoidal choroidal vasculopathy (PCV in a patient with angioid streaks. PCV was detected during a routine ophthalmic examination and confirmed by fluorescein angiography, indocyanine green angiography, and optical coherence tomography. After 2 years of follow-up, the PCV remained silent without any complications. We report this rare coexistence and review literature on this topic.

  2. Choroidal Coloboma in a Case of Tay-Sachs Disease

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    Nasreen Raees Ahmed

    2014-01-01

    Full Text Available Coloboma as an ocular finding has been documented in various syndromes. Here we have a case of infantile Tay-Sachs disease associated with unilateral choroidal coloboma. To the best of our knowledge, such an association has not been documented in the literature. Whether such an association is a matter of chance or signifies the involvement of ganglioside metabolism in ocular embryogenesis remains to be elucidated.

  3. MACULAR CHOROIDAL VOLUME CHANGES AFTER INTRAVITREAL BEVACIZUMAB FOR EXUDATIVE AGE-RELATED MACULAR DEGENERATION.

    Science.gov (United States)

    Palkovits, Stefan; Seidel, Gerald; Pertl, Laura; Malle, Eva M; Hausberger, Silke; Makk, Johanna; Singer, Christoph; Osterholt, Julia; Herzog, Sereina A; Haas, Anton; Weger, Martin

    2017-12-01

    To evaluate the effect of intravitreal bevacizumab on the macular choroidal volume and the subfoveal choroidal thickness in treatment naïve eyes with exudative age-related macular degeneration. The macular choroidal volume and the subfoveal choroidal thickness were measured using enhanced depth imaging optical coherence tomography. After a screening examination, each patient received 3 monthly intravitreal injections of 1.25 mg bevacizumab. One month after the third injection was a final assessment. Forty-seven patients with a mean age of 80 ± 6.4 years were included. The macular choroidal volume decreased significantly from median 4.1 mm (interquartile range 3.4-5.9) to median 3.9 mm (interquartile range 3.1-5.6) between the baseline and final examination (difference -0.46 mm, 95% confidence interval: -0.57 to 0.35, P macular choroidal volume at baseline and subfoveal choroidal thickness at baseline were not associated with the response to treatment. The macular choroidal volume and the subfoveal choroidal thickness decreased significantly after 3 monthly bevacizumab injections for exudative age-related macular degeneration.

  4. Visual Loss from Choroidal Melanoma Mimicking Neurological Syndromes

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    Karim Hammamji

    2017-03-01

    Full Text Available Melanoma of the eye is rare, but can mimic a range of disorders. This report highlights 2 cases of choroidal melanoma with vision loss mimicking neurological diagnoses. The first patient is a 41-year-old white male with a known history of multiple sclerosis and a previous episode of optic neuritis in the right eye, who presented with a 6-month history of decreased vision in the same eye, and occasional photopsiae. He was treated with 2 courses of oral steroids for presumed recurrent optic neuritis. After a temporary improvement in his symptoms, his vision worsened, following which he had a head MRI, which revealed a solid intraocular mass. He was subsequently diagnosed with a choroidal melanoma for which he was treated successfully with ruthenium-106 plaque brachytherapy. The second patient is a 57-year-old female, who presented with a progressive cerebellar syndrome under investigation by the neurology service, as well as decreased vision in the right eye. Her visual acuity gradually deteriorated and her neurological assessment, which included a PET-CT, revealed uptake in the right eye. The diagnosis of a choroidal melanoma was made, and following conservative treatment with proton beam radiotherapy, she had an enucleation of the eye. Intraocular tumours can masquerade as many different entities. Unexplained unilateral visual loss, especially if it is atypical for a neurological syndrome, should prompt dilated fundoscopy and referral to an ophthalmologist.

  5. Focal choroidal excavation in patients with central serous chorioretinopathy

    Science.gov (United States)

    Luk, F O J; Fok, A C T; Lee, A; Liu, A T W; Lai, T Y Y

    2015-01-01

    Purpose To evaluate the prevalence and clinical features of focal choroidal excavation (FCE) in patients presenting with central serous chorioretinopathy (CSC). Methods This is a retrospective consecutive case series of consecutive patients with CSC who were referred for spectral domain optical coherence tomography (SD-OCT) between January 2010 and December 2011. Medical records were reviewed and clinical features including presence of FCE in SD-OCT, fluorescence angiography (FA), and indocyanine green angiography (ICGA) were studied. Results Among the 116 CSC patients assessed, FCE was found in 11 eyes of 7 (6.0%) patients. FCE was associated with subretinal fluid in six eyes of six patients and serous pigment epithelial detachment in three eyes of two patients. The mean central subfield retinal thickness of CSC eyes with FCE was 283.7 μm, compared with 377.5 μm for CSC eyes without FCE (Mann–Whitney U-test, P=0.020). Five FCE eyes of five patients had focal leakage on FA. Choroidal hyperpermeability on ICGA was found in seven CSC eyes with FCE, with four eyes showing hypofluorescent spot corresponding to the FCE. After a mean follow-up of 16 months, visual acuity of all 11 eyes with FCE remained stable or improved at the last follow-up. Conclusion FCE is not an uncommon feature in patients with CSC and might be associated with choroidal hemodynamic disturbances. PMID:25853402

  6. Clinicopathologic findings in choroidal melanomas after failed transpupillary thermotherapy.

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    Zaldivar, Renzo A; Aaberg, Thomas M; Sternberg, Paul; Waldron, Rhonda; Grossniklaus, Hans E

    2003-05-01

    To review the clinicopathologic features of eyes enucleated after failed transpupillary thermotherapy. Retrospective review. Pathology reports in the L.F. Montgomery Laboratory between 1998 and 2002 were searched for enucleated eyes with choroidal melanoma that had been treated only by transpupillary thermotherapy (TTT) prior to enucleation. The clinical features of the patients, including ultrasonography examination, were reviewed and compared with the pathologic findings. Seven eyes from seven patients had been enucleated, representing 8% of eyes treated with TTT at our institute during the period studied. The primary indication for enucleation was tumor growth. The melanomas tended to grow laterally, with minimal if any increase in thickness. Five of the seven eyes histologically demonstrated extrascleral extension, which was detected by ultrasonography prior to enucleation in only one of those eyes. Choroidal melanoma may continue to grow along a path of least resistance after TTT. The melanoma may extend laterally in the choroid and through emissary canals. Early extrascleral extension may be difficult to detect by ultrasonography.

  7. Detection of epidermoid squamous-cell carcinoma by laser induced autofluorescence – preliminary results

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    Romeo Costin

    2016-07-01

    Full Text Available Epidermoid squamous-cell carcinoma is by far the most common malignant tumor of larynx (95-96%, representing 1.6-2% of cancers in men and 0.2-0.4% of malignancies in females, with a world growing incidence and a slight dominance in urban areas. By exposing cells and tissues to UV light, the excitation of naturally occurring chromophores occurs in part by non-radiative deactivations, in part via fluorescence emission. Using laser induced autofluorescence (LIAF in natural tissues not impregnated with photosensitizers as a noninvasive autofluorescence technique for both diagnosis and intraoperative assessments of laryngeal cancer we can improve the tumor malign identification in vivo. A total of three laryngeal biopsies (i.e. three pairs of tissues, each pair containing a healthy and a tumor tissue sample extracted from the same patient were considered in this study. The samples were collected from patients previously diagnosed with stage T3 laryngeal carcinoma. Immediately after the surgery fragments of normal tissue and neoplastic tissue were collected, fragments of which later, after freezing, were sectioned in 25-30 μm thickness slices and stretched to quartz slides. All samples were subjected to controlled laser irradiation using a pulsed diode laser (λ=375nm, pulse width=87ps, frequency 31MHz and the autofluorescence and its lifetime were collected using two optical fibers (inner diameter 400µm and 1500µm, respectively positioned in a 45o geometry. The signals were recorded using a spectrograph and a photo-sensor module, the output of which was fed to a digital oscilloscope. We assessed the impact of laser induced autofluorescence and autofluorescence lifetime measurements in order to identify the differences between healthy and tumoral laryngeal tissue and outlining them, in terms of differences between the laser autoinduced fluorescence averaged intensity. The results determined the usefulness of laser induced spectroscopy in the

  8. UV-laser-induced densification of fused silica: A molecular dynamics study

    Science.gov (United States)

    Zheng, Lianqing

    Fused silica (amorphous silicon dioxide, a-SiO 2) is a choice optical material in semiconductor-fabrication lithography due to its many excellent optical, mechanical, physical, and chemical properties. UV-laser-induced densification in fused silica has been observed and intensive experimental work has focused on this phenomenon. However, the mechanism of UV-laser-induced densification of fused silica still remains unclear and poorly understood. In the present thesis, we have performed classical molecular dynamics simulations to study the relationships between 193-nm UV-laser-induced densification and absorbed laser fluence (J/cm2) under different laser pulse durations (from 50 ps to 12500 ps), pressures (-1 GPa, 0 GPa, 2 GPa, and 4 GPa), and temperatures (200 K, 300 K, and 500 K) and how UV-laser irradiation affects the microstructural properties (radial distribution functions, coordination number, neutron static structure factor, total correlation function, bond-angle distributions, and ring-size distribution) and the elastic constants of fused silica. The fused silica simulation cell contains 502 silicon atoms and 1004 oxygen atoms and periodic boundary conditions are applied in all three directions. The effect of laser irradiation is modeled as energy transfer from the absorbed laser photons to bonded silicon and oxygen atoms in silica. The absorbed energy is equivalent to a laser wavelength of 193 nm and two-photon absorption is also applied. The induced densification is found to, at first, increase with laser fluence, but tends to reach saturation or even decrease at higher fluence. Longer laser pulse duration produces larger densification under the same fluence. Higher pressure or higher temperature also causes more densification. The Si-O bond length increases slightly with fused-silica density, whereas the O-O distance decreases notably. Over-coordinated Si and O atoms appear upon irradiation and increase in number with densification. The medium

  9. Choroidal Thickness in Turkish Children with Anisometric Amblyopia.

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    Karaca, Emine Esra; Çubuk, Mehmet Özgür; Akçam, Hanife Tuba; Uzun, Feyzahan; Yüksel, Erdem

    2017-01-01

    To assess macular choroidal thickness (CT) and axial length measurements in children with anisometropic amblyopia and to compare the measurements with that of fellow non-amblyopic eyes and age-sex matched controls. Forty patients with anisometropic amblyopia and 40 age-/sex-matched controls were evaluated in this study. Eyes were classified into three groups as follows: amblyopic eyes (n = 40), fellow non-amblyopic eyes, and healthy eyes (n = 40). All subjects underwent complete ophthalmic examination and macular choroidal thickness measurements by enhanced depth imaging method of the Spectralis optical coherence tomography system. CT was measured at the fovea and at 1000-μm intervals from the foveal center in both temporal and nasal directions. The statistical assessment was performed with the assistance of one-way analysis of variance (ANOVA) and Pearson's correlation test. The mean subfoveal CT was 389.35, 349.07, and 315.8 μm in the amblyopic, fellow non-amblyopic and healthy eyes, respectively. Choroid was thickest in subfoveal and thinnest in nasal regions among all groups. Both amblyopic and fellow non-amblopic eyes were more hyperopic than healthy eyes. While the subfoveal and nasal CT in amblyopic eyes and fellow eyes were significantly higher than healthy eyes, the temporal CT in amblyopic eyes was significantly higher than in healthy eyes. There was a significant positive correlation between the CT of the subfoveal, nasal, and temporal regions and the refractive state (r = 0.432 p = 0.001; r = 0.324 p = 0.001; r = 0.215 p = 0.01, respectively). The macular choroidal thickness-not only in amblyopic eyes but also in non-amblyopic fellow eyes-was significantly thicker than in the healthy subjects. The thick choroid in amblyopic and non-amblyopic fellow eyes may indicate bilateral delay of emmetropization, which probably means amblyopia affecting the visual feedback of both eyes.

  10. Anti-vascular endothelial growth factors for choroidal neovascularization secondary to choroidal osteoma: Long-term results

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    T Lekha

    2015-01-01

    Full Text Available Choroidal osteoma is an uncommon benign osseous intraocular tumor typically seen unilaterally in young women. Visual loss can occur due to choroidal neovascularization (CNV complicating osteoma. We report a rare case of bilateral choroidal osteoma with secondary CNV in a young male and the long-term results following anti-vascular endothelial growth factor (VEGF therapy. A 30-year-old male with history of defective vision in both eyes since several years and recent worsening in the right eye (RE since 2 months was found to have bilateral macular osteoma with CNV in the RE based on clinical evaluation, fluorescein angiography, optical coherence tomography, and ultrasonography. Intravitreal injection of ranibizumab at monthly intervals for three doses resulted in resolution of CNV and remained stable for 5 years. Recurrent CNV detected 6 years later responded to an injection of intravitreal bevacizumab and has remained stable till date. Anti-VEGF therapy stabilized the secondary CNV in our patient for 7 years with satisfactory structural and functional outcome, demonstrating the long-term efficacy of this modality of treatment.

  11. Choroidal thickness in non-ocular Behçet's disease – A spectral-domain OCT study

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    Aman Mittal

    2017-09-01

    Conclusion: This study demonstrates that BD may have subclinical manifestations in the choroid, resulting in thinning of the choroid relative to normal eyes, even without overt signs of ocular involvement.

  12. ASSOCIATION OF DRUSEN VOLUME WITH CHOROIDAL PARAMETERS IN NONNEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

    Science.gov (United States)

    Balasubramanian, Siva; Lei, Jianqin; Nittala, Muneeswar G; Velaga, Swetha B; Haines, Jonathan; Pericak-Vance, Margaret A; Stambolian, Dwight; Sadda, SriniVas R

    2017-10-01

    The choroid is thought to be relevant to the pathogenesis of nonneovascular age-related macular degeneration, but its role has not yet been fully defined. In this study, we evaluate the relationship between the extent of macular drusen and specific choroidal parameters, including thickness and intensity. Spectral domain optical coherence tomography images were collected from two distinct, independent cohorts with nonneovascular age-related macular degeneration: Amish (53 eyes of 34 subjects) and non-Amish (40 eyes from 26 subjects). All spectral domain optical coherence tomography scans were obtained using the Cirrus HD-OCT with a 512 × 128 macular cube (6 × 6 mm) protocol. The Cirrus advanced retinal pigment epithelium analysis tool was used to automatically compute drusen volume within 3 mm (DV3) and 5 mm (DV5) circles centered on the fovea. The inner and outer borders of the choroid were manually segmented, and the mean choroidal thickness and choroidal intensity (i.e., brightness) were calculated. The choroidal intensity was normalized against the vitreous and nerve fiber layer reflectivity. The correlation between DV and these choroidal parameters was assessed using Pearson and linear regression analysis. A significant positive correlation was observed between normalized choroidal intensity and DV5 in the Amish (r = 0.42, P = 0.002) and non-Amish (r = 0.33, P = 0.03) cohorts. Also, DV3 showed a significant positive correlation with normalized choroidal intensity in both the groups (Amish: r = 0.30, P = 0.02; non-Amish: r = 0.32, P = 0.04). Choroidal thickness was negatively correlated with normalized choroidal intensity in both Amish (r = -0.71, P = 0.001) and non-Amish (r = -0.43, P = 0.01) groups. Normalized choroidal intensity was the most significant constant predictor of DV in both the Amish and non-Amish groups. Choroidal intensity, but not choroidal thickness, seems to be associated with drusen volume in Amish and non-Amish populations. These

  13. Evaluation of focal choroidal excavation in the macula using swept-source optical coherence tomography

    Science.gov (United States)

    Lim, F P M; Loh, B K; Cheung, C M G; Lim, L S; Chan, C M; Wong, D W K

    2014-01-01

    Purpose To evaluate imaging findings of patients with focal choroidal excavation (FCE) in the macula using swept-source optical coherence tomography (SS-OCT) and correlate it clinically. Methods Prospective observational case series. Eleven consecutive patients (12 eyes) with FCE were described. Data on demographics and clinical presentation were collected and imaging findings (including color photography, fundus autofluorescence imaging, fluorescein angiography, indocyanine green angiography, spectral-domain optical coherence tomography, and SS-OCT) were analyzed. Results The primary diagnosis was epiretinal membrane (two eyes), choroidal neovascularization (one eye), polypoidal choroidal vasculopathy (three eyes), central serous chorioretinopathy (one eye), and dry age-related macular degeneration (two eyes). Eleven out of 12 of the lesions were conforming. One presented with a non-conforming lesion that progressed to a conforming lesion. One eye had multiFCE and two had two overlapping choroidal excavations. Using the SS-OCT, we found the choroid to be thinned out at the area of FCE but sclera remained normal. The choroidal tissue beneath the FCE was abnormal, with high internal reflectivity and poor visualization of choroidal vessels. There was loss of contour of the outer choroidal boundary that appeared to be pulled inward by this abnormal choroidal tissue. A suprachoroidal space was noted beneath this choroidal tissue and the choroidal–scleral interface was smooth. Repeat SS-OCT 6 months after presentation showed the area of excavation to be stable in size. Conclusion FCE can be associated with epiretinal membrane, central serous chorioretinopathy, and age-related macular degeneration. The choroid was thinned out in the area of FCE. PMID:24946847

  14. Using laser-induced spin manipulation to build magnetic nanologic elements

    Science.gov (United States)

    Hübner, W.; Kersten, S.; Lefkidis, G.

    2010-01-01

    We present an ab initio theory of ultrafast nanologic elements and show that controlled spin manipulation is feasible with the inclusion of spin-orbit coupling in Λ-processes. We show that in branched metallic chains with three magnetic centers both spin flips and spin transfers are possible within a hundred femtoseconds. A static external magnetic field and the magnetic state of one magnetic center serve as input poles (input bits), while the magnetic state of the cluster after a controlled laser pulse can be mapped to the output. Combining laser-induced spin-manipulation scenarios we are able to construct the NAND logic. Thus multicenter magnetic clusters can extend spin dynamics to optically triggered and functionalized magnetic transport on a subpicosecond timescale and nanometer spatial scale.

  15. Compact low-cost detector for in vivo assessment of microphytobenthos using laser induced fluorescence

    Science.gov (United States)

    Utkin, A. B.; Vieira, S.; Marques da Silva, J.; Lavrov, A.; Leite, E.; Cartaxana, P.

    2013-03-01

    The development of a compact low-cost detector for non-destructive assessment of microphytobenthos using laser induced fluorescence was described. The detector was built from a specially modified commercial miniature fiber optic spectrometer (Ocean Optics USB4000). Its usefulness is experimentally verified by the study of diatom-dominated biofilms inhabiting the upper layers of intertidal sediments of the Tagus Estuary, Portugal. It is demonstrated that, operating with a laser emitter producing 30 mJ pulses at the wavelength of 532 nm, the detector is capable to record fluorescence signals with sufficient intensity for the quantitative biomass characterization of the motile epipelic microphytobenthic communities and to monitor their migratory activity. This paves the way for building an entire emitter-detector LIF system for microphytobenthos monitoring, which will enable microalgae communities occupying hardly accessible intertidal flats to be monitored in vivo at affordable cost.

  16. A LabVIEW-Based Virtual Instrument System for Laser-Induced Fluorescence Spectroscopy.

    Science.gov (United States)

    Wu, Qijun; Wang, Lufei; Zu, Lily

    2011-01-01

    We report the design and operation of a Virtual Instrument (VI) system based on LabVIEW 2009 for laser-induced fluorescence experiments. This system achieves synchronous control of equipment and acquisition of real-time fluorescence data communicating with a single computer via GPIB, USB, RS232, and parallel ports. The reported VI system can also accomplish data display, saving, and analysis, and printing the results. The VI system performs sequences of operations automatically, and this system has been successfully applied to obtain the excitation and dispersion spectra of α-methylnaphthalene. The reported VI system opens up new possibilities for researchers and increases the efficiency and precision of experiments. The design and operation of the VI system are described in detail in this paper, and the advantages that this system can provide are highlighted.

  17. Electron density and temperature diagnostics in laser-induced hydrogen plasma

    Science.gov (United States)

    Gautam, G.; Parigger, C. G.

    2017-02-01

    Laser-induced optical breakdown is achieved by using Q-switched, Nd:YAG radiation focused into ultra-high-purity (UHP) hydrogen gas at a pressure of 1.08 ± 0.03 × 105 Pa inside a cell. The plasma emission spectra are dispersed by a Czerny-Turner type spectrometer and detected with an intensified charge-coupled device (ICCD). Stark-broadened hydrogen Balmer series H α and Hβ line profiles are used as a spectroscopic tool for the determination of electron density and excitation temperature. Spatial variation of electron density and temperature at 0.40 µs are extracted from the recorded intensities of H α and Hβ lines. Temporal variations of electron density and excitation temperature are also presented for the time delay range of 0.15 µs to 1.4 µs.

  18. Lidar remote sensing of laser-induced incandescence on light absorbing particles in the atmosphere.

    Science.gov (United States)

    Miffre, Alain; Anselmo, Christophe; Geffroy, Sylvain; Fréjafon, Emeric; Rairoux, Patrick

    2015-02-09

    Carbon aerosol is now recognized as a major uncertainty on climate change and public health, and specific instruments are required to address the time and space evolution of this aerosol, which efficiently absorbs light. In this paper, we report an experiment, based on coupling lidar remote sensing with Laser-Induced-Incandescence (LII), which allows, in agreement with Planck's law, to retrieve the vertical profile of very low thermal radiation emitted by light-absorbing particles in an urban atmosphere over several hundred meters altitude. Accordingly, we set the LII-lidar formalism and equation and addressed the main features of LII-lidar in the atmosphere by numerically simulating the LII-lidar signal. We believe atmospheric LII-lidar to be a promising tool for radiative transfer, especially when combined with elastic backscattering lidar, as it may then allow a remote partitioning between strong/less light absorbing carbon aerosols.

  19. Laser ablation-laser induced breakdown spectroscopy for the measurement of total elemental concentration in soils.

    Science.gov (United States)

    Pareja, Jhon; López, Sebastian; Jaramillo, Daniel; Hahn, David W; Molina, Alejandro

    2013-04-10

    The performances of traditional laser-induced breakdown spectroscopy (LIBS) and laser ablation-LIBS (LA-LIBS) were compared by quantifying the total elemental concentration of potassium in highly heterogeneous solid samples, namely soils. Calibration curves for a set of fifteen samples with a wide range of potassium concentrations were generated. The LA-LIBS approach produced a superior linear response different than the traditional LIBS scheme. The analytical response of LA-LIBS was tested with a large set of different soil samples for the quantification of the total concentration of Fe, Mn, Mg, Ca, Na, and K. Results showed an acceptable linear response for Ca, Fe, Mg, and K while poor signal responses were found for Na and Mn. Signs of remaining matrix effects for the LA-LIBS approach in the case of soil analysis were found and discussed. Finally, some improvements and possibilities for future studies toward quantitative soil analysis with the LA-LIBS technique are suggested.

  20. Application of laser induced fluorescence analysis to nuclear fuel reprocessing plant

    Energy Technology Data Exchange (ETDEWEB)

    Hayashibara, Hirofumi; Miyake, Takafumi; Izumi, Jyun [Mitsubishi Heavy Industries Ltd., Takasago, Hyogo (Japan). Takasago Research and Development Center; Taguchi, Syouzou; Watanabe, Ryuuichi

    1996-09-01

    In nuclear fuel reprocessing plants, to maintain the system integrity, many kinds of chemical analysis must be done. However, with chemical analysis performed under a high radiation field, to reduce the occupational radiation exposure, a new type of trace analysis technique is desirable, concerning the technique of trace analysis, a laser ray method enables us to achieve higher sensitivity and selectivity than the conventional methods, due to its higher energy and narrow spectral width. Then, we developed a laser induced fluorescence (LIF) method and performed an application study for fuel reprocessing plants by using the simulated samples. Main investigated analyzed elements are an impurities of uranium in nitric acid solution. As a result of this investigation, a pretreatment procedure of analysis was found to be simple compared with the conventional analysis method. (author)