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Sample records for laser engraving methods

  1. Ultrafast Laser Engraving Method to Fabricate Gravure Plate for Printed Metal-Mesh Touch Panel

    Weiyuan Chen

    2015-10-01

    Full Text Available In order to engrave gravure plate with fine lines structures, conventional art used lithography with dry/wet etching. Lithography with dry/wet etching method allows to engrave lines with smooth concave shape, but its disadvantages include difficulty in controlling aspect ratio, high and uniform in large size process, substrate material limitation due to etching solution availability, and process complexity. We developed ultra-fast laser technology to directly engrave a stainless plate, a gravure plate, to be used for fabricating 23 in. metal-mesh touch panel by gravure offset printing process. The technology employs high energy pulse to ablate materials from a substrate. Because the ultra-fast laser pulse duration is shorter than the energy dissipation time between material lattices, there is no heating issue during the ablation process. Therefore, no volcano-type protrusion on the engraved line edges occurs, leading to good printing quality. After laser engraving, we then reduce surface roughness of the gravure plate using electro-polishing process. Diamond like carbon (DLC coating layer is then added onto the surface to increase scratch resistance. We show that this procedure can fabricate gravure plate for gravure offset printing process with minimum printing linewidth 10.7 μm. A 23 in. metal-mesh pattern was printed using such gravure plate and fully functional touch panel was demonstrated in this work.

  2. Atmospheric pressure plasma-assisted femtosecond laser engraving of aluminium

    Gerhard, Christoph; Gimpel, Thomas; Tasche, Daniel; Koch née Hoffmeister, Jennifer; Brückner, Stephan; Flachenecker, Günter; Wieneke, Stephan; Schade, Wolfgang; Viöl, Wolfgang

    2018-05-01

    In this contribution, we report on the impact of direct dielectric barrier discharge argon plasma at atmospheric pressure on femtosecond laser engraving of aluminium. It is shown that the assisting plasma strongly affects the surface geometry and formation of spikes of both laser-engraved single lines and patterns of adjacent lines with an appropriate overlap. Further, it was observed that the overall ablation depth is significantly increased in case of large-scale patterning whereas no notable differences in ablation depth are found for single lines. Several possible mechanisms and underlying effects of this behaviour are suggested. The increase in ablation depth is supposed to be due to a plasma-induced removal of debris particles from the cutting point via charging and oxidation as supported by EDX analysis of the re-solidified debris. Furthermore, the impact of a higher degree of surface wrinkling as well as direct interactions of plasma species with the aluminium surface on the ablation process are discussed.

  3. UV laser engraving of high temperature polymeric materials

    Martinez, D.; Laude, L.D.; Kolev, K.; Hanus, F.

    1999-01-01

    Among emerging technologies, those associated with laser sources as surface processing tools are quite promising. In the present work, a UV pulsed (excimer) laser source is experimented for engraving (or ablating) polymeric materials based on three high temperature polymers: polyethylene terephtalate (PET), polyethersulfone (PES) and polyphenylene sulfide (PPS). The ablation phenomenon is demonstrated on all these polymers and evaluated by stylus profilometry upon varying the laser fluence at impact. For each polymer, results give evidence for three characteristic quantities: an ablation threshold E sub 0, a maximum ablation depth per pulse z sub 0 and an initial rate of ablation α, just above threshold. A simple ablation model is presented which describes correctly the observed behaviours and associates closely the above quantities to the polymer formulation, thus providing for the first time a rational basis to polymer ablation. The model may be extended to parent plastic materials whenever containing the same polymers. It may also be used to predict the behaviours of other polymers when subjected to excimer laser irradiation

  4. Diffraction efficiency enhancement of femtosecond laser-engraved diffraction gratings due to CO2 laser polishing

    Choi, Hun-Kook; Jung, Deok; Sohn, Ik-Bu; Noh, Young-Chul; Lee, Yong-Tak; Kim, Jin-Tae; Ahsan, Shamim

    2014-01-01

    This research demonstrates laser-assisted fabrication of high-efficiency diffraction gratings in fused-silica glass samples. Initially, femtosecond laser pulses are used to engrave diffraction gratings on the glass surfaces. Then, these micro-patterned glass samples undergo CO 2 laser polishing process. unpolished diffraction gratings encoded in the glass samples show an overall diffraction efficiency of 18.1%. diffraction gratings imprinted on the glass samples and then polished four times by using a CO 2 laser beam attain a diffraction efficiency of 32.7%. We also investigate the diffraction patterns of the diffraction gratings encoded on fused-silica glass surfaces. The proposed CO 2 laser polishing technique shows great potential in patterning high-efficiency diffraction gratings on the surfaces of various transparent materials.

  5. HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

    Sandoval Amador, A.; Carreño Garcia, H.; Escobar Rivero, P.; Peña Ballesteros, D. Y.; Estupiñán Duran, H. A.

    2016-02-01

    The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti6Al4V surfaces were evaluated. Ti6Al4V surfaces were textured using a CO2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment.

  6. HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

    Sandoval Amador, A; Carreño Garcia, H; Escobar Rivero, P; Peña Ballesteros, D Y; Estupiñán Duran, H A

    2016-01-01

    The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti 6 Al 4 V surfaces were evaluated. Ti 6 Al 4 V surfaces were textured using a CO 2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment. (paper)

  7. Diffraction efficiency enhancement of femtosecond laser-engraved diffraction gratings due to CO{sub 2} laser polishing

    Choi, Hun-Kook [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Chosun University, Gwangju (Korea, Republic of); Jung, Deok; Sohn, Ik-Bu; Noh, Young-Chul; Lee, Yong-Tak [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Kim, Jin-Tae [Chosun University, Gwangju (Korea, Republic of); Ahsan, Shamim [Khulna University, Khulna (Bangladesh)

    2014-11-15

    This research demonstrates laser-assisted fabrication of high-efficiency diffraction gratings in fused-silica glass samples. Initially, femtosecond laser pulses are used to engrave diffraction gratings on the glass surfaces. Then, these micro-patterned glass samples undergo CO{sub 2} laser polishing process. unpolished diffraction gratings encoded in the glass samples show an overall diffraction efficiency of 18.1%. diffraction gratings imprinted on the glass samples and then polished four times by using a CO{sub 2} laser beam attain a diffraction efficiency of 32.7%. We also investigate the diffraction patterns of the diffraction gratings encoded on fused-silica glass surfaces. The proposed CO{sub 2} laser polishing technique shows great potential in patterning high-efficiency diffraction gratings on the surfaces of various transparent materials.

  8. Engraving Print Classification

    Hoelck, Daniel; Barbe, Joaquim

    2008-01-01

    A print is a mark, or drawing, made in or upon a plate, stone, woodblock or other material which is cover with ink and then is press usually into a paper reproducing the image on the paper. Engraving prints usually are image composed of a group of binary lines, specially those are made with relief and intaglio techniques. Varying the number and the orientation of lines, the drawing of the engraving print is conformed. For this reason we propose an application based on image processing methods to classify engraving prints

  9. Laser-engraved carbon nanotube paper for instilling high sensitivity, high stretchability, and high linearity in strain sensors

    Xin, Yangyang

    2017-06-29

    There is an increasing demand for strain sensors with high sensitivity and high stretchability for new applications such as robotics or wearable electronics. However, for the available technologies, the sensitivity of the sensors varies widely. These sensors are also highly nonlinear, making reliable measurement challenging. Here we introduce a new family of sensors composed of a laser-engraved carbon nanotube paper embedded in an elastomer. A roll-to-roll pressing of these sensors activates a pre-defined fragmentation process, which results in a well-controlled, fragmented microstructure. Such sensors are reproducible and durable and can attain ultrahigh sensitivity and high stretchability (with a gauge factor of over 4.2 × 10(4) at 150% strain). Moreover, they can attain high linearity from 0% to 15% and from 22% to 150% strain. They are good candidates for stretchable electronic applications that require high sensitivity and linearity at large strains.

  10. Correlative microscopy including CLSM and SEM to improve high-speed, high-resolution laser-engraved print and embossing forms

    Bohrer, Markus; Schweitzer, Michael; Nirnberger, Robert; Weinberger, Bernhard

    2015-10-01

    The industrial market for processing large-scale films has seen dramatic changes since the 1980s and has almost completely been replaced by lasers and digital processes. A commonly used technology for engraving screens, print and embossing forms in the printing industry, well known since then, is the use of RF-excited CO2 lasers with a beam power up to about 1 kW, modulated in accordance to the pattern to be engraved. Future needs for high-security printing (banknotes, security papers, passports, etc.) will require laser engraving of at least half a million or even more structured elements with a depth from some μm up to 500 μm. Industry now wants photorealistic pictures in packaging design, which requires a similar performance. To ensure 'trusted pulses' from the digital process to the print result the use of correlative microscopy (CLSM and SEM) is demonstrated as a complete chain for a correlative print process in this paper.

  11. Fir Engraver (FIDL)

    George T. Ferrell

    1986-01-01

    The fir engraver, Scolytus ventralis LeConte, belongs to the family of insects called bark beetles, which live between the bark and wood of host trees. A wide-ranging, native beetle, the fir engraver attacks most species of fir in the Western United States. Epidemics can cause severe tree mortality. From 1977 to 1978, for example, the fir engraver killed an estimated 1...

  12. The X'tal cube PET detector with a monolithic crystal processed by the 3D sub-surface laser engraving technique: Performance comparison with glued crystal elements

    Yoshida, Eiji, E-mail: rush@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Hirano, Yoshiyuki; Tashima, Hideaki; Inadama, Naoko; Nishikido, Fumihiko [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Moriya, Takahiro; Omura, Tomohide; Watanabe, Mitsuo [Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu, Shizuoka 434-8601 (Japan); Murayama, Hideo; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

    2013-09-21

    The X'tal cube is a depth-of-interaction (DOI)-PET detector which is aimed at obtaining isotropic resolution by effective readout of scintillation photons from six sides of the crystal block. The X'tal cube is composed of a 3D crystal block with isotropic segments. Each face of the 3D crystal block is covered with a 4×4 array of multi-pixel photon counters (MPPCs). Previously, in order to fabricate the 3D crystal block efficiently and precisely, we applied a sub-surface laser engraving technique to a monolithic crystal block instead of gluing segmented small crystals. A dense arrangement of multiple micro-cracks carved by the laser beam works efficiently as a scattering wall for the scintillation photons. The X'tal cube with the laser-processed block showed excellent performance with respect to crystal identification and energy resolution. In this work, for characteristics comparison between the laser-processed block and the conventional segmented array block, we made the laser-processed block and two types of segmented array blocks, one with air gaps and the other with glued segmented small crystals. All crystal blocks had 3D grids of 2 mm pitch. The 4×4 MPPC arrays were optically coupled to each surface of the crystal block. When performance was evaluated using a uniform irradiation of 511 keV, we found that the X'tal cubes with the laser-processed block could easily achieve 2 mm{sup 3} uniform crystal identification. Also, the average energy resolution of each 3D grid was 11.1±0.7%. On the other hand, the glued segmented array block had a pinched distribution and crystals could not be separated clearly. The segmented array block with air gaps had satisfactory crystal identification performance; however, the laser-processed block had higher crystal identification performance. Also, the energy resolution of the laser-processed block was better than for the segmented array blocks. In summary, we found the laser-processed X'tal cube had

  13. Research on a Novel Parallel Engraving Machine and its Key Technologies

    Zhang Shi-hui

    2008-11-01

    Full Text Available In order to compensate the disadvantages of conventional engraving machine and exert the advantages of parallel mechanism, a novel parallel engraving machine is presented and some key technologies are studied in this paper. Mechanism performances are analyzed in terms of the first and the second order influence coefficient matrix firstly. So the sizes of mechanism, which are better for all the performance indices of both kinematics and dynamics, can be confirmed and the restriction due to considering only the first order influence coefficient matrix in the past is broken through. Therefore, the theory basis for designing the mechanism size of novel engraving machine with better performances is provided. In addition, method for tool path planning and control technology for engraving force is also studied in the paper. The proposed algorithm for tool path planning on curved surface can be applied to arbitrary spacial curved surface in theory, control technology for engraving force based on fuzzy neural network(FNN has well adaptability to the changing environment. Research on teleoperation for parallel engraving machine based on B/S architecture resolves the key problems such as control mode, sharing mechanism for multiuser, real-time control for engraving job and real-time transmission for video information. Simulation results further show the feasibility and validity of the proposed methods.

  14. Research on a Novel Parallel Engraving Machine and its Key Technologies

    Kong Ling-fu

    2004-12-01

    Full Text Available In order to compensate the disadvantages of conventional engraving machine and exert the advantages of parallel mechanism, a novel parallel engraving machine is presented and some key technologies are studied in this paper. Mechanism performances are analyzed in terms of the first and the second order influence coefficient matrix firstly. So the sizes of mechanism, which are better for all the performance indices of both kinematics and dynamics, can be confirmed and the restriction due to considering only the first order influence coefficient matrix in the past is broken through. Therefore, the theory basis for designing the mechanism size of novel engraving machine with better performances is provided. In addition, method for tool path planning and control technology for engraving force is also studied in the paper. The proposed algorithm for tool path planning on curved surface can be applied to arbitrary spacial curved surface in theory, control technology for engraving force based on fuzzy neural network(FNN has well adaptability to the changing environment. Research on teleoperation for parallel engraving machine based on B/S architecture resolves the key problems such as control mode, sharing mechanism for multiuser, real-time control for engraving job and real-time transmission for video information. Simulation results further show the feasibility and validity of the proposed methods.

  15. Laser pulse stacking method

    Moses, E.I.

    1992-12-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  16. Laser device and method

    Myers, J.D.

    1986-01-01

    A method is described of treatment of opacity of the lens of an eye resulting from foreign matter at the back surface of the eye lens within the vitreous fluid body of the eye with a passively Q-switched laser device. The method consists of: (a) generating a single lasing pulse emitted from the laser device focused within the eye vitreous fluid body, spaced from the lens back surface, creating a microplasma dot in the vitreous fluid body (b) then increasing the frequency of the lasing pulses emitted from the lasing device having a frequency greater than the life of the microplasma to generate an elongated lasing plasma within the eye vitreous fluid moving toward the lens back surface, until the elongated lasing plasma contacts and destroys the foreign matter

  17. Anesthesia Methods in Laser Resurfacing

    Gaitan, Sergio; Markus, Ramsey

    2012-01-01

    Laser resurfacing technology offers the ability to treat skin changes that are the result of the aging process. One of the major drawbacks of laser resurfacing technologies is the pain associated with the procedure. The methods of anesthesia used in laser resurfacing to help minimize the pain include both noninvasive and invasive procedures. The noninvasive procedures can be divided into topical, cryoanesthesia, and a combination of both. The invasive methods of anesthesia include injected fo...

  18. Anesthesia Methods in Laser Resurfacing

    Gaitan, Sergio; Markus, Ramsey

    2012-01-01

    Laser resurfacing technology offers the ability to treat skin changes that are the result of the aging process. One of the major drawbacks of laser resurfacing technologies is the pain associated with the procedure. The methods of anesthesia used in laser resurfacing to help minimize the pain include both noninvasive and invasive procedures. The noninvasive procedures can be divided into topical, cryoanesthesia, and a combination of both. The invasive methods of anesthesia include injected forms (infiltrative, nerve blocks, and tumescent anesthesia) and supervised anesthesia (monitored anesthesia care and general anesthesia). In this review, the authors summarize the types of anesthesia used in laser resurfacing to aid the provider in offering the most appropriate method for the patient to have as painless a procedure as possible. PMID:23904819

  19. Wavefront holoscopy: application of digital in-line holography for the inspection of engraved marks in progressive addition lenses.

    Perucho, Beatriz; Micó, Vicente

    2014-01-01

    Progressive addition lenses (PALs) are engraved with permanent marks at standardized locations in order to guarantee correct centering and alignment throughout the manufacturing and mounting processes. Out of the production line, engraved marks provide useful information about the PAL as well as act as locator marks to re-ink again the removable marks. Even though those marks should be visible by simple visual inspection with the naked eye, engraving marks are often faint and weak, obscured by scratches, and partially occluded and difficult to recognize on tinted or antireflection-coated lenses. Here, we present an extremely simple optical device (named as wavefront holoscope) for visualization and characterization of permanent marks in PAL based on digital in-line holography. Essentially, a point source of coherent light illuminates the engraved mark placed just before a CCD camera that records a classical Gabor in-line hologram. The recorded hologram is then digitally processed to provide a set of high-contrast images of the engraved marks. Experimental results are presented showing the applicability of the proposed method as a new ophthalmic instrument for visualization and characterization of engraved marks in PALs.

  20. Dynamic analysis of a guided projectile during engraving process

    Tao Xue

    2014-06-01

    Full Text Available The reliability of the electronic components inside a guided projectile is highly affected by the launch dynamics of guided projectile. The engraving process plays a crucial role on determining the ballistic performance and projectile stability. This paper analyzes the dynamic response of a guided projectile during the engraving process. By considering the projectile center of gravity moving during the engraving process, a dynamics model is established with the coupling of interior ballistic equations. The results detail the stress situation of a guided projectile band during its engraving process. Meanwhile, the axial dynamic response of projectile in the several milliseconds following the engraving process is also researched. To further explore how the different performance of the engraving band can affect the dynamics of guided projectile, this paper focuses on these two aspects: (a the effects caused by the different band geometry; and (b the effects caused by different band materials. The time domain and frequency domain responses show that the dynamics of the projectile are quite sensitive to the engraving band width. A material with a small modulus of elasticity is more stable than one with a high modulus of elasticity.

  1. The Oval Engravings of Nabara 2 (Ennedi, Chad

    Alessandro Menardi Noguera

    2017-09-01

    Full Text Available By revisiting the Nabara 2 shelter in the southern Ennedi (Chad, some previously unreported paintings and a whole set of unexpected oval engravings were surveyed. These engravings, internally decorated with patterns of lines, some featured by a single longitudinal element or a sort of reticular structure, make Nabara 2 an unparalleled site among the hundreds known in the region. Comparison with similar motifs associated to human depictions found at the western termination of the Ennedi Highland suggests these engravings could be depictions of shields, attributable to the pastoral period.

  2. Laser marking method and device

    Okazaki, Yuki; Aoki, Nobutada; Mukai, Narihiko; Sano, Yuji; Yamamoto, Seiji.

    1997-01-01

    An object is disposed in laser beam permeating liquid or gaseous medium. Laser beams such as CW laser or pulse laser oscillated from a laser device are emitted to the object to apply laser markings with less degradation of identification and excellent corrosion resistance on the surface of the object simply and easily. Upon applying the laser markings, a liquid or gas as a laser beam permeating medium is blown onto the surface of the object, or the liquid or gas in the vicinity of the object is sucked, the laser beam-irradiated portion on the surface can be cooled positively. Accordingly, the laser marking can be formed on the surface of the object with less heat affection to the object. In addition, if the content of a nitrogen gas in the laser beam permeating liquid medium is reduced by degassing to lower than a predetermined value, or the laser beam permeating gaseous medium is formed by an inert gas, a laser marking having high corrosion resistance and reliability can be formed on the surface of the objective member. (N.H.)

  3. [The decoration of Italian Renaissance drug jars after engravings].

    Drey, R E

    1994-01-01

    Although Italian drug jar painters generally devised original compositions for the ornamentation of their products, on occasion they derived their subjects from printed sources. Printed sources used by drug jar artists of the Renaissance include wood-engraved Italian tarot cards and wood-engraved illustrations by Hans Sebald Beham and Bernard Salomon in miniature bibles published in the sixteenth century in Frankfurt and in Lyons respectively.

  4. Multifunctional cube-like system for biomedical applications featuring 3D printing by dual deposition, scanner, and UV engraving

    Guzmán-González, J. V.; Saldaña-Martínez, M. I.; Barajas-González, O. G.; Guzmán-Ramos, V.; García-Garza, A. K.; Franco-Herrada, M. G.; Selvas Aguilar, R. J.; García-Ramírez, M. A.

    2017-02-01

    In this paper, a cubic-like structure is proposed to scan and print tools used as medical equipment at low cost for developing countries. The structure features a 3-axis frame plane that uses high-precision step motors. An actuator drives the "x and y" axis through serrated bands with 2 mm pitch. Those give an accuracy of 2.5 microns tops. The z-axe is driven by and inductive sensor that allows us to keep the focus to the printing bed as well as to search for non-smooth areas to correct it and deliver an homogeneous impression. The 3D scanner as well as the entire gears are placed underneath in order to save space. As extrude tip, we are using a 445 nm UV laser with 2000 mW of power. The laser system is able to perform several functions such as crystallizing, engraving or cut though a set of mirror arrays. Crystallization occurs when the laser is guided towards the base. This process allows us to direct it towards the polymer injector and as a result, it crystalizes on the spot. Another feature that this system is the engraving process that occurs while the base moves. The movement allows the beam to pass freely towards the base and perform the engraving process.

  5. Method of controlling chaos in laser equations

    Duong-van, M.

    1993-01-01

    A method of controlling chaotic to laminar flows in the Lorenz equations using fixed points dictated by minimizing the Lyapunov functional was proposed by Singer, Wang, and Bau [Phys. Rev. Lett. 66, 1123 (1991)]. Using different fixed points, we find that the solutions in a chaotic regime can also be periodic. Since the laser equations are isomorphic to the Lorenz equations we use this method to control chaos when the laser is operated over the pump threshold. Furthermore, by solving the laser equations with an occasional proportional feedback mechanism, we recover the essential laser controlling features experimentally discovered by Roy, Murphy, Jr., Maier, Gills, and Hunt [Phys. Rev. Lett. 68, 1259 (1992)

  6. Method of controlling chaos in laser equations

    Duong-van, Minh

    1993-01-01

    A method of controlling chaotic to laminar flows in the Lorenz equations using fixed points dictated by minimizing the Lyapunov functional was proposed by Singer, Wang, and Bau [Phys. Rev. Lett. 66, 1123 (1991)]. Using different fixed points, we find that the solutions in a chaotic regime can also be periodic. Since the laser equations are isomorphic to the Lorenz equations we use this method to control chaos when the laser is operated over the pump threshold. Furthermore, by solving the laser equations with an occasional proportional feedback mechanism, we recover the essential laser controlling features experimentally discovered by Roy, Murphy, Jr., Maier, Gills, and Hunt [Phys. Rev. Lett. 68, 1259 (1992)].

  7. Composition of the bacterial community in the gut of the pine engraver, Ips pini (Say) (Coloptera) colonizing red pine

    Italo Jr. Delalibera; Archana Vasanthakumar; Benjamin J. Burwitz; Patrick D. Schloss; Kier D. Klepzig; Jo Handelsman; Kenneth F. Raffa

    2007-01-01

    The gut bacterial community of a bark beetle, the pine engraver Ips pini (Say), was characterized using culture-dependent and culture-independent methods. Bacteria from individual guts of larvae, pupae and adults were cultured and DNA was extracted from samples of pooled larval guts. Analysis of 16S rRNA gene sequences amplified directly from the gut...

  8. U.S. Mint - Bureau of Engraving and Printing (BEP) Facilities

    Department of Homeland Security — United States Mint - Bureau of Engraving and Printing Facilities This dataset includes facilities of the United States Mint and facilities of the Bureau of Engraving...

  9. Rock Engravings and Sculptures of North Guwahati, Assam

    Dwipen Bezbaruah

    2016-02-01

    Full Text Available Evidences of rock engravings and sculptures, in Assam, are predominantly found to occur in the vicinity of the temples. Incidence of images of Gods and Goddesses, faunal and floral motif are invariably more. Apart from these, some geometric designs are also perceived. Such tangible archaeological heritages are considered important evidences for understanding the past in a more meaningful way. Therefore, it is pertinent to systematically document these sites and the remains before natural and anthropogenic obliteration. The objective of the present paper is to record and document the rock engravings and sculptures observed in the archaeological sites, namely Dirgheswari, Aswakranta, Manikarneswar, Rudreswar and Kanai Boroshi bowa of North Guwahati in Kamrup district, Assam, which are protected and preserved by the Directorate of Archaeology, Assam and to understand the archaeological context of the sites and their remains. The data for the present paper have been collected through field visit and Exploration was conducted in dry and winter season. The findings of the present work comprises of some sculptures of Ganesa, Yama, Sage, Kali, deities, bull without head, human figures, broken piece of a tiger, remains of door frame or pillar and shrines. Series of dot marks, cut marks, inscription, image of Shiva, foot impression, chess board, square, bow, signs, female figurine, and elephant engravings constitute the rock engravings observed in the area.

  10. A rock engraving made by Neanderthals in Gibraltar.

    Rodríguez-Vidal, Joaquín; d'Errico, Francesco; Giles Pacheco, Francisco; Blasco, Ruth; Rosell, Jordi; Jennings, Richard P; Queffelec, Alain; Finlayson, Geraldine; Fa, Darren A; Gutiérrez López, José María; Carrión, José S; Negro, Juan José; Finlayson, Stewart; Cáceres, Luís M; Bernal, Marco A; Fernández Jiménez, Santiago; Finlayson, Clive

    2014-09-16

    The production of purposely made painted or engraved designs on cave walls--a means of recording and transmitting symbolic codes in a durable manner--is recognized as a major cognitive step in human evolution. Considered exclusive to modern humans, this behavior has been used to argue in favor of significant cognitive differences between our direct ancestors and contemporary archaic hominins, including the Neanderthals. Here we present the first known example of an abstract pattern engraved by Neanderthals, from Gorham's Cave in Gibraltar. It consists of a deeply impressed cross-hatching carved into the bedrock of the cave that has remained covered by an undisturbed archaeological level containing Mousterian artifacts made by Neanderthals and is older than 39 cal kyr BP. Geochemical analysis of the epigenetic coating over the engravings and experimental replication show that the engraving was made before accumulation of the archaeological layers, and that most of the lines composing the design were made by repeatedly and carefully passing a pointed lithic tool into the grooves, excluding the possibility of an unintentional or utilitarian origin (e.g., food or fur processing). This discovery demonstrates the capacity of the Neanderthals for abstract thought and expression through the use of geometric forms.

  11. Method for laser spot welding monitoring

    Manassero, Giorgio

    1994-09-01

    As more powerful solid state laser sources appear on the market, new applications become technically possible and important from the economical point of view. For every process a preliminary optimization phase is necessary. The main parameters, used for a welding application by a high power Nd-YAG laser, are: pulse energy, pulse width, repetition rate and process duration or speed. In this paper an experimental methodology, for the development of an electrooptical laser spot welding monitoring system, is presented. The electromagnetic emission from the molten pool was observed and measured with appropriate sensors. The statistical method `Parameter Design' was used to obtain an accurate analysis of the process parameter that influence process results. A laser station with a solid state laser coupled to an optical fiber (1 mm in diameter) was utilized for the welding tests. The main material used for the experimental plan was zinc coated steel sheet 0.8 mm thick. This material and the related spot welding technique are extensively used in the automotive industry, therefore, the introduction of laser technology in production line will improve the quality of the final product. A correlation, between sensor signals and `through or not through' welds, was assessed. The investigation has furthermore shown the necessity, for the modern laser production systems, to use multisensor heads for process monitoring or control with more advanced signal elaboration procedures.

  12. Laser beam cutting method. Laser ko ni yoru kaitai koho

    Kutsumizu, A. (Obayashi Corp., Osaka (Japan))

    1991-07-01

    In this special issue paper concerning the demolition of concrete structures, was introduced a demolition of concrete structures using laser, of which practical application is expected due to the remarkable progress of generating power and efficiency of laser radiator. The characteristics of laser beam which can give a temperature of one million centigrade at the irradiated spot, the laser radiator consisting of laser medium, laser resonator and pumping apparatus, and the laser kinds for working, such as CO{sub 2} laser, YAG laser and CO laser, were described. The basic constitution of laser cutting equipment consisting of large generating power radiator, beam transmitter, beam condenser, and nozzle for working was also illustrated. Furthermore, strong and weak points in the laser cutting for concrete and reinforcement were enumerated. Applications of laser to cutting of reinforced and unreinforced concrete constructions were shown, and the concept and safety measure for application of laser to practical demolition was discussed. 5 refs., 8 figs.

  13. Study of inks on paper engravings using portable EDXRF spectrometry

    Ferrero, J.L.; Roldan, C.; Juanes, D.; Carballo, J.; Pereira, J.; Ardid, M.; Lluch, J.L.; Vives, R.

    2004-01-01

    The prints are fragile and delicate art objects that need for its examination a suitable technique for 'in situ', non-destructive and rapid analyses. The energy dispersive X-ray Fluorescence (EDXRF) spectrometry with portable instrumentation offers these analytical properties. In this work we present the EDXRF analyses of eight engravings elaborated with different techniques (etching and heliogravure) from the 17th to 20th centuries. The characterization of the paper is directly done from its EDXRF spectra, whereas the inks are characterized by the ink plus paper analysis after subtracting the background from the paper spectrum. Inorganic components of the paper engravings and inks have been identified from the EDXRF spectra and the results are discussed. Also, we present EDXRF analyses for the identification of inorganic components from six samples of modern inks

  14. From the Prehispanic Codices to the Engravings Inspirited by Poems

    Gabriela Toma

    2015-01-01

    Full Text Available This article debates the importance of shaping a community's identity and the artist's identity within one culture starting from the Prehispanic pictograms - where the sense allows itself to be discovered as the image is internalized, this double sense being similar to the reading of the works of Mexican artists Jose Guadalupe Posada, Diego Rivera and Frida Kahlo similar to the engraving of the poems of Nichita Stanescu by Mircia Dumitrescu.

  15. Characteristics of the Arcing Plasma Formation Effect in Spark-Assisted Chemical Engraving of Glass, Based on Machine Vision

    Chao-Ching Ho; Dung-Sheng Wu

    2018-01-01

    Spark-assisted chemical engraving (SACE) is a non-traditional machining technology that is used to machine electrically non-conducting materials including glass, ceramics, and quartz. The processing accuracy, machining efficiency, and reproducibility are the key factors in the SACE process. In the present study, a machine vision method is applied to monitor and estimate the status of a SACE-drilled hole in quartz glass. During the machining of quartz glass, the spring-fed tool electrode was p...

  16. Repetitive output laser system and method using target reflectivity

    Johnson, R.R.

    1978-01-01

    An improved laser system and method for implosion of a thermonuclear fuel pellet is described in which that portion of a laser pulse reflected by the target pellet is utilized in the laser system to initiate a succeeding target implosion, and in which the energy stored in the laser system to amplify the initial laser pulse, but not completely absorbed thereby, is used to amplify succeeding laser pulses initiated by target refγlection

  17. Lasers and new methods of particle acceleration

    Parsa, Z.

    1998-02-01

    There has been a great progress in development of high power laser technology. Harnessing their potential for particle accelerators is a challenge and of great interest for development of future high energy colliders. The author discusses some of the advances and new methods of acceleration including plasma-based accelerators. The exponential increase in sophistication and power of all aspects of accelerator development and operation that has been demonstrated has been remarkable. This success has been driven by the inherent interest to gain new and deeper understanding of the universe around us. With the limitations of the conventional technology it may not be possible to meet the requirements of the future accelerators with demands for higher and higher energies and luminosities. It is believed that using the existing technology one can build a linear collider with about 1 TeV center of mass energy. However, it would be very difficult (or impossible) to build linear colliders with energies much above one or two TeV without a new method of acceleration. Laser driven high gradient accelerators are becoming more realistic and is expected to provide an alternative, (more compact, and more economical), to conventional accelerators in the future. The author discusses some of the new methods of particle acceleration, including laser and particle beam driven plasma based accelerators, near and far field accelerators. He also discusses the enhanced IFEL (Inverse Free Electron Laser) and NAIBEA (Nonlinear Amplification of Inverse-Beamstrahlung Electron Acceleration) schemes, laser driven photo-injector and the high energy physics requirements

  18. Initial alignment method for free space optics laser beam

    Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

    2016-08-01

    The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

  19. Laser method of free atom nuclei orientation

    Barabanov, A.L.

    1987-01-01

    Orientation process of free atom (atoms in beams) nuclei, scattering quanta of circularly polarized laser radiation is considered. A method for the evaluation of nuclei orientation parameters is developed. It is shown that in the process of pumping between the ground and first excited atomic states with electron shell spins J 1 and J 2 , so that J 2 = J 1 + 1, a complete orientation of nuclei can be attained

  20. Applications of Friction Stir Processing during Engraving of Soft Materials

    V. Kočović

    2015-12-01

    Full Text Available Friction stir processing has extensive application in many technological operations. Application area of friction stir processing can be extended to the processing of non-metallic materials, such as wood. The paper examines the friction stir processing contact between a specially designed hard and temperature-resistant rotating tool and workpiece which is made of wood. Interval of speed slip and temperature level under which the combustion occurs and carbonization layer of soft material was determined. The results of the research can be applied in technological process of wood engraving operations which may have significant technological and aesthetic effects.

  1. The gematrical numbers in dimensions of the "Melencolia I" engraving

    Tine Kurent

    1998-12-01

    Full Text Available The Melancholy engraving by Dürer and Agrippa is hiding its gematrical messages not only in the numbers of its magic square but also in the numbers forming its modular dimensions. If the sphere on the lower left side of the composition is 10 modules in diameter, the magic square measures 8 by 8 modules, and the print is 70 by 55 modules large. The circumference of the etching equals 250 and its diagonal 89 modules. In the numbers 55, 70, 250 and 89 are hidden gematrical messages, prayers, cursing, the name of the Melancholia itself and the names of its authors.

  2. Study on Laser Welding Process Monitoring Method

    Knag , Heeshin

    2017-01-01

    International audience; In this paper, a study of quality monitoring technology for the laser welding was conducted. The laser welding and the industrial robotic systems were used with robot-based laser welding systems. The laser system used in this study was 1.6 kW fiber laser, while the robot system was Industrial robot (pay-load : 130 kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plat...

  3. Study on Laser Welding Process Monitoring Method

    Heeshin Knag

    2016-01-01

    In this paper, a study of quality monitoring technology for the laser welding was conducted. The laser welding and the industrial robotic systems were used with robot-based laser welding systems. The laser system used in this study was 1.6 kW fiber laser, while the robot system was Industrial robot (pay-load : 130 kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plate coated with zinc were ...

  4. A trial of direct control of pine engraver beetles on a small logging unit

    W. L. Jackson

    1960-01-01

    Laboratory tests and small-scale field trials have shown the insecticide lindane to be highly toxic to pine engraver beetles. On the basis of that information, the insecticide was applied to fresh logging slash heavily infested with pine engraver beetles at Challenge Experimental Forest in 1959. Costs were reasonable and no insurmountable problems were encountered....

  5. An iconographic study of the engraving of the Consecration, the Flemish artist Abraham van Diepenbeeck

    Juan Isaac Calvo Portela

    2017-06-01

    Full Text Available In this article we study a engraving from the workshop of flemish artist, Abraham van Diepenbeeck, who opened the engraver Mattheus Borrekens and published Martinus van den Enden the Elder, between the late 1640s and early 1650s. In the Courtland Institute of London is preserved a previus sketch of this engraving, which allows us to approach the analysis of the creative process of the engraving. In this engraving are expressed many of the doctrines that the Council of Trent established on the Eucharist is expressed, and at the same time, it tries to deal the position of Jansenism on the Sacramento and also it opposes to the idea of frequent Communion, idea that was defended among others the Jesuits.

  6. Method for mounting laser fusion targets for irradiation

    Fries, R. Jay; Farnum, Eugene H.; McCall, Gene H.

    1977-07-26

    Methods for preparing laser fusion targets of the ball-and-disk type are disclosed. Such targets are suitable for irradiation with one or two laser beams to produce the requisite uniform compression of the fuel material.

  7. Polarization methods for diode laser excitation of solid state lasers

    Holtom, Gary R.

    2008-11-25

    A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. A Yb-doped gain medium can be used that absorbs light having a first polarization and emits light having a second polarization. Using such pumping with laser cavity dispersion control, pulse durations of less than 100 fs can be achieved.

  8. METHOD AND SYSTEM FOR LASER WELDING

    2008-01-01

    The invention relates to laser welding of at least two adjacent, abutting or overlapping work pieces in a welding direction using multiple laser beams guided to a welding region, wherein at least two of the multiple laser beams are coupled into the welding region so as to form a melt and at least...

  9. Selection of Near Optimal Laser Cutting Parameters in CO2 Laser Cutting by the Taguchi Method

    Miloš MADIĆ

    2013-12-01

    Full Text Available Identification of laser cutting conditions that are insensitive to parameter variations and noise is of great importance. This paper demonstrates the application of Taguchi method for optimization of surface roughness in CO2 laser cutting of stainless steel. The laser cutting experiment was planned and conducted according to the Taguchi’s experimental design using the L27 orthogonal array. Four laser cutting parameters such as laser power, cutting speed, assist gas pressure, and focus position were considered in the experiment. Using the analysis of means and analysis of variance, the significant laser cutting parameters were identified, and subsequently the optimal combination of laser cutting parameter levels was determined. The results showed that the cutting speed is the most significant parameter affecting the surface roughness whereas the influence of the assist gas pressure can be neglected. It was observed, however, that interaction effects have predominant influence over the main effects on the surface roughness.

  10. Method of stabilizing a laser apparatus with wavelength converter

    2013-01-01

    and to output the frequency-converted radiation (213), the frequency-converted radiation having at least a second wavelength different from the first wavelength, the diode laser (10) comprising at least a first and a second section (222,223), a first contact (220) for injecting a first current (I1......) into the first section (222), a second contact (221) for injecting a second current (I2) into the second section (223), and means for controlling a temperature of the diode laser; wherein the method comprises monitoring a first parameter indicative of the power content of a dominant lobe of the first radiation......A method of controlling beam quality and stability of a laser apparatus, the laser apparatus comprising, a diode laser (10) providing first radiation of at least a first wavelength, and a frequency conversion unit (12) configured to frequency-convert the first radiation from the diode laser...

  11. New photonuclear methods based on femtosecond lasers

    Ivanov, K.A.; Shulyapov, S.A.; Savel'ev, A.B.; Uryupina, D.S.; Volkov, R.V.; Rusakov, A.V.; Turinge, A.A.; Dzhilkibaev, R.M.; Nedorezov, V.G.; Brantov, A.V.; Bychenkov, V.Yu.

    2014-01-01

    Results of X-ray diagnostics of plasma created on the surface of matter by laser pulse with an intensity of 2.5 · 10 18 W/cm 2 are presented in the paper. Comparison of experimental data with the results of numerical simulation of laser-plasma interaction is made taking into account the response functions of the detector. Examples of possible nuclear tasks realizable with the use of laser plasma as a source of charged particles and X rays are given

  12. Development of laser excited atomic fluorescence and ionization methods

    Winefordner, J.D.

    1991-01-01

    Progress report: May 1, 1988 to December 31, 1991. The research supported by DE-FG05-88ER13881 during the past (nearly) 3 years can be divided into the following four categories: (1) theoretical considerations of the ultimate detection powers of laser fluorescence and laser ionization methods; (2) experimental evaluation of laser excited atomic fluorescence; (3) fundamental studies of atomic and molecular parameters in flames and plasmas; (4) other studies

  13. An overview of the laser ranging method of space laser altimeter

    Zhou, Hui; Chen, Yuwei; Hyyppä, Juha; Li, Song

    2017-11-01

    Space laser altimeter is an active remote sensing instrument to measure topographic map of Earth, Moon and planetary. The space laser altimeter determines the range between the instrument and laser footprint by measuring round trip time of laser pulse. The return pulse reflected from ground surface is gathered by the receiver of space laser altimeter, the pulsewidth and amplitude of which are changeable with the variability of the ground relief. Meantime, several kinds of noise overlapped on the return pulse signal affect its signal-to-noise ratio. To eliminate the influence of these factors that cause range walk and range uncertainty, the reliable laser ranging methods need to be implemented to obtain high-precision range results. Based on typical space laser altimeters in the past few decades, various ranging methods are expounded in detail according to the operational principle of instruments and timing method. By illustrating the concrete procedure of determining time of flight of laser pulse, this overview provides the comparison of the employed technologies in previous and undergoing research programs and prospect innovative technology for space laser altimeters in future.

  14. Methods for Optimisation of the Laser Cutting Process

    Dragsted, Birgitte

    This thesis deals with the adaptation and implementation of various optimisation methods, in the field of experimental design, for the laser cutting process. The problem in optimising the laser cutting process has been defined and a structure for at Decision Support System (DSS......) for the optimisation of the laser cutting process has been suggested. The DSS consists of a database with the currently used and old parameter settings. Also one of the optimisation methods has been implemented in the DSS in order to facilitate the optimisation procedure for the laser operator. The Simplex Method has...... been adapted in two versions. A qualitative one, that by comparing the laser cut items optimise the process and a quantitative one that uses a weighted quality response in order to achieve a satisfactory quality and after that maximises the cutting speed thus increasing the productivity of the process...

  15. Development of laser cutting method for stainless steel liner

    Ishihara, Satoshi; Takahata, Masato; Wignarajah, Sivakumaran; Kamata, Hirofumi

    2007-01-01

    The present work is an attempt to develop a laser cutting method for cutting and removing stainless steel liners from concrete walls and floors in nuclear facilities. The effect of basic laser cutting parameters such as energy, cutting speed, assist gas flow etc. were first studied through cutting experiments on mock-up concrete specimens lined with 3mm thick stainless steel sheets using a 1kW Nd:YAG laser. These initial studies were followed by further studies on the effect of unevenness of the liner surface and on a new method of confining contamination during the cutting process using a sliding evacuation hood attached to the laser cutting head. The results showed that laser cutting is superior to other conventional cutting methods from the point of view of safety from radioactivity and work efficiency when cutting contaminated stainless steel liners. (author)

  16. Technique for Increasing the Selectivity of the Method of Laser Fragmentation/Laser-Induced Fluorescence

    Bobrovnikov, S. M.; Gorlov, E. V.; Zharkov, V. I.

    2018-05-01

    A technique for increasing the selectivity of the method of detecting high-energy materials (HEMs) based on laser fragmentation of HEM molecules with subsequent laser excitation of fluorescence of the characteristic NO fragments from the first vibrational level of the ground state is suggested.

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

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

    2017-10-01

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

  18. Laser filamentation mathematical methods and models

    Lorin, Emmanuel; Moloney, Jerome

    2016-01-01

    This book is focused on the nonlinear theoretical and mathematical problems associated with ultrafast intense laser pulse propagation in gases and in particular, in air. With the aim of understanding the physics of filamentation in gases, solids, the atmosphere, and even biological tissue, specialists in nonlinear optics and filamentation from both physics and mathematics attempt to rigorously derive and analyze relevant non-perturbative models. Modern laser technology allows the generation of ultrafast (few cycle) laser pulses, with intensities exceeding the internal electric field in atoms and molecules (E=5x109 V/cm or intensity I = 3.5 x 1016 Watts/cm2 ). The interaction of such pulses with atoms and molecules leads to new, highly nonlinear nonperturbative regimes, where new physical phenomena, such as High Harmonic Generation (HHG), occur, and from which the shortest (attosecond - the natural time scale of the electron) pulses have been created. One of the major experimental discoveries in this nonlinear...

  19. Efficient method for transport simulations in quantum cascade lasers

    Maczka Mariusz

    2017-01-01

    Full Text Available An efficient method for simulating quantum transport in quantum cascade lasers is presented. The calculations are performed within a simple approximation inspired by Büttiker probes and based on a finite model for semiconductor superlattices. The formalism of non-equilibrium Green’s functions is applied to determine the selected transport parameters in a typical structure of a terahertz laser. Results were compared with those obtained for a infinite model as well as other methods described in literature.

  20. Self-seeded single-frequency laser peening method

    DAne, C Brent; Hackey, Lloyd A; Harris, Fritz B

    2012-06-26

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  1. Long life gas laser system and method

    Hochuli, E.E.

    1975-01-01

    A long life gas discharge laser having an improved self-repairing cathode system is described. In a specific embodiment, water vapor having a partial pressure below about 10 -5 torr incorporated in a molecular sieve is used to provide impurities (in this case water vapor) for repairing the cathode surface by regenerating the oxide surface and/or preventing same from deteriorating. Other impurities may be incorporated in the molecular sieve such as hydrogen, oxygen, for example. In some cases CO 2 may be used. This application includes material disclosed in a paper entitled ''Continuation of the Investigation into Material Properties Affecting the Frequency Stability and Reliability of He-Ne Laser Structures'' submitted to the Office of Naval Research dated June 1972 by the inventor hereof and also a paper entitled ''Investigations of the Long Term Frequency Stability of Stable Laser Structures'' Progress Report for ONR Contract N00014-67-A-D239-0016 July 1972 by the inventor hereof. A royalty free license is hereby granted to the United States for use of the invention for all government purposes. (auth)

  2. Method of laser beam coding for control systems

    Pałys, Tomasz; Arciuch, Artur; Walczak, Andrzej; Murawski, Krzysztof

    2017-08-01

    The article presents the method of encoding a laser beam for control systems. The experiments were performed using a red laser emitting source with a wavelength of λ = 650 nm and a power of P ≍ 3 mW. The aim of the study was to develop methods of modulation and demodulation of the laser beam. Results of research, in which we determined the effect of selected camera parameters, such as image resolution, number of frames per second on the result of demodulation of optical signal, is also shown in the paper. The experiments showed that the adopted coding method provides sufficient information encoded in a single laser beam (36 codes with the effectiveness of decoding at 99.9%).

  3. [The celestial phenomena in A. Dürer's engraving Melancholia I].

    Weitzel, Hans

    2009-01-01

    The celestial body of Dürer's engraving Melencolia I is connected with his painting of a meteor, the Raveningham-painting; it is shown that the origin of this painting owns to the impact of the meteor of Ensisheim in 1492. Until now the celestial body, the balance, and the magic square are nearly consistently interpreted as the planet Saturn, the zodiac sign Libra, and the planet Jupiter, and the melancholy woman is subject to these heavenly bodies. Consequently, neoplatonic astrology has been the main focus of the engraving; including the rainbow, the engraving has also been interpreted biblically. The present paper, however, places emphasis on problems of the geometry as the reason of melancholy. Any astronomical meaning of the configuration of the numbers of the magic square is discarded.

  4. Glass Imprint Templates by Spark Assisted Chemical Engraving for Microfabrication by Hot Embossing

    Lucas Abia Hof

    2017-01-01

    Full Text Available As the field of microelectromechanical systems (MEMS matures, new demands are being placed on the microfabrication of complex architectures in robust materials, such as hard plastics. Iterative design optimization in a timely manner—rapid prototyping—places challenges on template fabrication, for methods such as injection moulding and hot embossing. In this paper, we demonstrate the possibility of using spark assisted chemical engraving (SACE to produce micro patterned glass templates. The direct, write-based approach enabled the facile fabrication of smooth microfeatures with variations in all three-dimensions, which could be replicated by hot embossing different thermoplastics. As a proof of principle, we demonstrated the technique for a high glass transition temperature polycarbonate. Good fidelity over more than 10 cycles provides evidence that the approach is viable for rapid prototyping and has the potential to satisfy commercial-grade production at medium-level output volumes. Glass imprint templates showed no degradation after use, but care must be taken due to brittleness. The technique has the potential to advance microfabrication needs in academia and could be used by MEMS product developers.

  5. Image Signal Transfer Method in Artificial Retina using Laser

    Yoon, I.Y.; Lee, B.H.; Kim, S.J. [Seoul National University, Seoul (Korea)

    2002-05-01

    Recently, the research on artificial retina for the blind is active. In this paper a new optical link method for the retinal prosthesis is proposed. Laser diode system was chosen to transfer image into the eye in this project and the new optical system was designed and evaluated. The use of laser diode array in artificial retina system makes system simple for lack of signal processing part inside of the eyeball. Designed optical system is enough to focus laser diode array on photodiode array in 20X20 application. (author). 11 refs., 7 figs., 2 tabs.

  6. Acoustic Emission Detection of Macro-Cracks on Engraving Tool Steel Inserts during the Injection Molding Cycle Using PZT Sensors

    Aleš Hančič

    2013-05-01

    Full Text Available This paper presents an improved monitoring system for the failure detection of engraving tool steel inserts during the injection molding cycle. This system uses acoustic emission PZT sensors mounted through acoustic waveguides on the engraving insert. We were thus able to clearly distinguish the defect through measured AE signals. Two engraving tool steel inserts were tested during the production of standard test specimens, each under the same processing conditions. By closely comparing the captured AE signals on both engraving inserts during the filling and packing stages, we were able to detect the presence of macro-cracks on one engraving insert. Gabor wavelet analysis was used for closer examination of the captured AE signals’ peak amplitudes during the filling and packing stages. The obtained results revealed that such a system could be used successfully as an improved tool for monitoring the integrity of an injection molding process.

  7. Enrichment of gadolinium-157 and gadolinium-155 by laser method

    Xinjun, Su; Xiaowei, Zhang; Zhiquan, Li

    2008-01-01

    Laser isotope separation experiments of gadolinium by atomic vapor method have been performed. Gadolinium-157 and gadolinium-155 were selectively photoionized by means of three linearly polarized dye lasers, the excitation process of which is based on the polarization selection rules. Gramme-magnitude of enriched gadolinium was obtained and the total abundance of gadolinium-157 and gadolinium-155 was in excess of 80%, and the product rating exceeded 200 mg/h. (author)

  8. Low energy methods of molecular laser isotope separation

    Makarov, G N

    2015-01-01

    Of the many proposals to date for laser-assisted isotope separation methods, isotope-selective infrared (IR) multiphoton dissociation (MPD) of molecules has been the most fully developed. This concept served as the basis for the development and operation of the carbon isotope separation facility in Kaliningrad, Russia. The extension of this method to heavy elements, including uranium, is hindered by, among other factors, the high power consumption and the lack of high-efficiency high-power laser systems. In this connection, research and development covering low energy methods for the laser separation of isotopes (including those of heavy atoms) is currently in high demand. This paper reviews approaches to the realization of IR-laser-induced isotope-selective processes, some of which are potentially the basis on which low-energy methods for molecular laser isotope separation can be developed. The basic physics and chemistry, application potential, and strengths and weaknesses of these approaches are discussed. Potentially promising alternatives to the title methods are examined. (reviews of topical problems)

  9. Method for laser welding a fin and a tube

    Fuerschbach, Phillip W.; Mahoney, A. Roderick; Milewski, John O

    2001-01-01

    A method of laser welding a planar metal surface to a cylindrical metal surface is provided, first placing a planar metal surface into approximate contact with a cylindrical metal surface to form a juncture area to be welded, the planar metal surface and cylindrical metal surface thereby forming an acute angle of contact. A laser beam, produced, for example, by a Nd:YAG pulsed laser, is focused through the acute angle of contact at the juncture area to be welded, with the laser beam heating the juncture area to a welding temperature to cause welding to occur between the planar metal surface and the cylindrical metal surface. Both the planar metal surface and cylindrical metal surface are made from a reflective metal, including copper, copper alloys, stainless steel alloys, aluminum, and aluminum alloys.

  10. Laser induced uranium fluorescence as an analytical method

    Krutman, I.

    1985-01-01

    A laser induced fluorescence system was developed to measure uranium trace level amounts in aqueous solution with reliable and simple materials and electronics. A nitrogen pulsed laser was built with the storage energy capacitor directly coupled to laser tube electrodes as a transmission line device. This laser operated at 3Hz repetition rate with peak intensity around 21 Kw and temporal width of 4.5 x 10 -9 s. A sample compartment made of rigid PVC and a photomultiplier housing of aluminium were constructed and assembled forming a single integrated device. As a result of this prototype system we made several analytical measurements with U dissolved in nitric acid to obtain a calibration curve. We obtained a straight line from a plot of U concentration versus fluorescence intensity fitted by a least square method that produced a regression coefficient of 0.994. The lower limit of U determination was 30 ppb -+ 3.5%. (Author) [pt

  11. Apparatus, system, and method for laser-induced breakdown spectroscopy

    Effenberger, Jr., Andrew J; Scott, Jill R; McJunkin, Timothy R

    2014-11-18

    In laser-induced breakdown spectroscopy (LIBS), an apparatus includes a pulsed laser configured to generate a pulsed laser signal toward a sample, a constructive interference object and an optical element, each located in a path of light from the sample. The constructive interference object is configured to generate constructive interference patterns of the light. The optical element is configured to disperse the light. A LIBS system includes a first and a second optical element, and a data acquisition module. The data acquisition module is configured to determine an isotope measurement based, at least in part, on light received by an image sensor from the first and second optical elements. A method for performing LIBS includes generating a pulsed laser on a sample to generate light from a plasma, generating constructive interference patterns of the light, and dispersing the light into a plurality of wavelengths.

  12. Speckle reduction methods in laser-based picture projectors

    Akram, M. Nadeem; Chen, Xuyuan

    2016-02-01

    Laser sources have been promised for many years to be better light sources as compared to traditional lamps or light-emitting diodes (LEDs) for projectors, which enable projectors having wide colour gamut for vivid image, super brightness and high contrast for the best picture quality, long lifetime for maintain free operation, mercury free, and low power consumption for green environment. A major technology obstacle in using lasers for projection has been the speckle noise caused by to the coherent nature of the lasers. For speckle reduction, current state of the art solutions apply moving parts with large physical space demand. Solutions beyond the state of the art need to be developed such as integrated optical components, hybrid MOEMS devices, and active phase modulators for compact speckle reduction. In this article, major methods reported in the literature for the speckle reduction in laser projectors are presented and explained. With the advancement in semiconductor lasers with largely reduced cost for the red, green and the blue primary colours, and the developed methods for their speckle reduction, it is hoped that the lasers will be widely utilized in different projector applications in the near future.

  13. Evaluation of insecticides for protecting southwestern ponderosa pines from attack by engraver beetles (Coleoptera: Curculionidae: Scolytinae)

    Tom E. DeGomez; Christopher J. Hayes; John A. Anhold; Joel D. McMillin; Karen M. Clancy; Paul P. Bosu

    2006-01-01

    Insecticides that might protect pine trees from attack by engraver beetles (Ips spp.) have not been rigorously tested in the southwestern United States. We conducted two field experiments to evaluate the efficacy of several currently and potentially labeled preventative insecticides for protecting high-value ponderosa pine, Pinus ponderosa...

  14. A history of engraving and etching techniques: developments of manual intaglio printmaking processes, 1400-2000

    Stijnman, A.C.J.

    2012-01-01

    This book surveys the history of the techniques of engraving, etching and plate printing - i.e. that of manual intaglio printmaking processes - from its beginning in the 1430s until today. These developments are observed in the light of the coherence between the technique of the intaglio print (such

  15. E-Myrcenol: A New Pheromone for the Pine Engraver, Ips Pini (Say) (Coleoptera: Scolytidae)

    D.R. Miller; G. Gries; J.H. Borden

    1990-01-01

    E-Myrcenol reduced catches of the pine engraver, Ips pini (Say), to ipsdienol-baited, multiple-funnel traps in a dose-dependent fashion. The sex ratio was unaffected by E-myrcenol treatments. Lures containing E-myrcenol in ethanol solution failed to protect freshly cut logs of lodgepole pine from attack by

  16. Weather, logging, and tree growth associated with fir engraver attack scars in white fir

    George T. Ferrell

    1973-01-01

    The boles of 32 recently killed, and 41 living, white fir were examined for embedded fir engraver (Scolytus ventralis) attack scars. Of 287 scars found in annual rings for the years 1934-69, only 2 to 3 percent represented reproductively successful attacks. Trends in scar abundance were directly correlated with trends in white fir killed by ...

  17. New laser power sensor using weighing method

    Pinot, P.; Silvestri, Z.

    2018-01-01

    We present a set-up using a piece of pyrolytic carbon (PyC) to measure laser power in the range from a few milliwatts to a few watts. The experimental configuration consists in measuring the magnetic repulsion force acting between a piece of PyC placed on a weighing pan and in a magnetic induction generated by a magnet array in a fixed position above the PyC sheet. This involves a repulsion force on the PyC piece which is expressed in terms of mass by the balance display. The quantities affecting the measurement results have been identified. An example of metrological characterization in terms of accuracy, linearity and sensitivity is given. A relative uncertainty of optical power measurement for the first experimental set-up is around 1%. The wavelength and power density dependence on power response of this device has been demonstrated. This PyC-based device presented here in weighing configuration and the other one previously studied in levitation configuration offer a new technique for measuring optical power.

  18. Laser and biological methods of biomonitoring of surrounding waters

    Posudin, Yuri I.

    1994-02-01

    Three main methods are proposed for the biomonitoring of chemicals in water medium: laser spectrofluorometry, which is based on the excitation and recording of the spectra of fluorescence; laser scattering, which is connected with measurement of the Doppler shifts of the scattered light from the motile cells; videomicrography, which provides the analysis of parameters of photomovement of motile cells via microscope and video system. Such chemicals as surface-active substances, heavy metals and pesticides were determined in water medium due to these methods.

  19. Characterization of nuclear graphite elastic properties using laser ultrasonic methods

    Zeng, Fan W.; Han, Karen; Olasov, Lauren R.; Gallego, Nidia C.; Contescu, Cristian I.; Spicer, James B.

    2015-05-01

    Laser ultrasonic methods have been used to characterize the elastic behaviors of commercially-available and legacy nuclear graphites. Since ultrasonic techniques are sensitive to various aspects of graphite microstructure including preferred grain orientation, microcrack orientation and porosity, laser ultrasonics is a candidate technique for monitoring graphite degradation and structural integrity in environments expected in high-temperature, gas-cooled nuclear reactors. Aspects of materials texture can be assessed by studying ultrasonic wavespeeds as a function of propagation direction and polarization. Shear wave birefringence measurements, in particular, can be used to evaluate elastic anisotropy. In this work, laser ultrasonic measurements of graphite moduli have been made to provide insight into the relationship between the microstructures and the macroscopic stiffnesses of these materials. In particular, laser ultrasonic measurements have been made using laser line sources to produce shear waves with specific polarizations. By varying the line orientation relative to the sample, shear wave birefringence measurements have been recorded. Results from shear wave birefringence measurements show that an isostatically molded graphite, such as PCIB, behaves isotropically, while an extruded graphite, such as H-451, displays significant ultrasonic texture. Graphites have complicated microstructures that depend on the manufacturing processes used, and ultrasonic texture in these materials could originate from grain orientation and preferred microcrack alignment. Effects on material isotropy due to service related microstructural changes are possible and the ultimate aim of this work is to determine the degree to which these changes can be assessed nondestructively using laser ultrasonics measurements.

  20. Exact extraction method for road rutting laser lines

    Hong, Zhiming

    2018-02-01

    This paper analyzes the importance of asphalt pavement rutting detection in pavement maintenance and pavement administration in today's society, the shortcomings of the existing rutting detection methods are presented and a new rutting line-laser extraction method based on peak intensity characteristic and peak continuity is proposed. The intensity of peak characteristic is enhanced by a designed transverse mean filter, and an intensity map of peak characteristic based on peak intensity calculation for the whole road image is obtained to determine the seed point of the rutting laser line. Regarding the seed point as the starting point, the light-points of a rutting line-laser are extracted based on the features of peak continuity, which providing exact basic data for subsequent calculation of pavement rutting depths.

  1. Study of inverse methods in remote sensing with laser

    Jesus, Wellington Carlos de

    2009-01-01

    The Laboratory of Environmental Applications of Lasers at IPEN realizes a study about atmospherics properties, such as extinction and backscattering coefficient. These coefficient are estimated by an inverse method, whose estimate quality is difficult to measure. This work presents a method with good statistic approach to retrieval the same coefficients. The new method, however, offers a number of advantages compared to the first method in use, including (1) the ability to incorporate different kinds of information under a common retrieval philosophy and (2) the method provides number of ways for evaluating the quality of the retrieval. Thus we hope improve the accuracy of estimates. (author)

  2. Laser methods of. gamma. spectroscopy without Doppler broadening

    Letokhov, V S [AN SSSR, Moscow. Inst. Spektroskopii

    1976-01-01

    Some new ideas and methods being conceived in a boundary area between atomic-molecular and nuclear physics are discussed. The recent progress with lasers tunable in the UV, visible, and IR should make the realization of these methods quite possible. There are at least two effects that link atomic and molecular transitions with nuclear transitions: they are the recoil effect and the Doppler effect.

  3. Methods for registration laser scanner point clouds in forest stands

    Bienert, A.; Pech, K.; Maas, H.-G.

    2011-01-01

    Laser scanning is a fast and efficient 3-D measurement technique to capture surface points describing the geometry of a complex object in an accurate and reliable way. Besides airborne laser scanning, terrestrial laser scanning finds growing interest for forestry applications. These two different recording platforms show large differences in resolution, recording area and scan viewing direction. Using both datasets for a combined point cloud analysis may yield advantages because of their largely complementary information. In this paper, methods will be presented to automatically register airborne and terrestrial laser scanner point clouds of a forest stand. In a first step, tree detection is performed in both datasets in an automatic manner. In a second step, corresponding tree positions are determined using RANSAC. Finally, the geometric transformation is performed, divided in a coarse and fine registration. After a coarse registration, the fine registration is done in an iterative manner (ICP) using the point clouds itself. The methods are tested and validated with a dataset of a forest stand. The presented registration results provide accuracies which fulfill the forestry requirements [de

  4. Laser target fabrication, structure and method for its fabrication

    Farnum, Eugene H.; Fries, R. Jay

    1985-01-01

    The disclosure is directed to a laser target structure and its method of fabrication. The target structure comprises a target plate containing an orifice across which a pair of crosshairs are affixed. A microsphere is affixed to the crosshairs and enclosed by at least one hollow shell comprising two hemispheres attached together and to the crosshairs so that the microsphere is juxtapositioned at the center of the shell.

  5. Method for nondestructive fuel assay of laser fusion targets

    Farnum, Eugene H.; Fries, R. Jay

    1976-01-01

    A method for nondestructively determining the deuterium and tritium content of laser fusion targets by counting the x rays produced by the interaction of tritium beta particles with the walls of the microballoons used to contain the deuterium and tritium gas mixture under high pressure. The x rays provide a direct measure of the tritium content and a means for calculating the deuterium content using the initial known D-T ratio and the known deuterium and tritium diffusion rates.

  6. Method for nondestructive fuel assay of laser fusion targets

    Farnum, E.H.; Fries, R.J.

    1976-01-01

    A method is described for nondestructively determining the deuterium and tritium content of laser fusion targets by counting the x rays produced by the interaction of tritium beta particles with the walls of the microballoons used to contain the deuterium and tritium gas mixture under high pressure. The x rays provide a direct measure of the tritium content and a means for calculating the deuterium content using the initial known D-T ratio and the known deuterium and tritium diffusion rates

  7. New method to estimate the frequency stability of laser signals

    McFerran, J.J.; Maric, M.; Luiten, A.N.

    2004-01-01

    A frequent challenge in the scientific and commercial use of lasers is the need to determine the frequency stability of the output optical signal. In this article we present a new method to estimate this quantity while avoiding the complexity of the usual technique. The new technique displays the result in terms of the usual time domain measure of frequency stability: the square root Allan variance

  8. Laser: a Tool for Optimization and Enhancement of Analytical Methods

    Preisler, Jan [Iowa State Univ., Ames, IA (United States)

    1997-01-01

    In this work, we use lasers to enhance possibilities of laser desorption methods and to optimize coating procedure for capillary electrophoresis (CE). We use several different instrumental arrangements to characterize matrix-assisted laser desorption (MALD) at atmospheric pressure and in vacuum. In imaging mode, 488-nm argon-ion laser beam is deflected by two acousto-optic deflectors to scan plumes desorbed at atmospheric pressure via absorption. All absorbing species, including neutral molecules, are monitored. Interesting features, e.g. differences between the initial plume and subsequent plumes desorbed from the same spot, or the formation of two plumes from one laser shot are observed. Total plume absorbance can be correlated with the acoustic signal generated by the desorption event. A model equation for the plume velocity as a function of time is proposed. Alternatively, the use of a static laser beam for observation enables reliable determination of plume velocities even when they are very high. Static scattering detection reveals negative influence of particle spallation on MS signal. Ion formation during MALD was monitored using 193-nm light to photodissociate a portion of insulin ion plume. These results define the optimal conditions for desorbing analytes from matrices, as opposed to achieving a compromise between efficient desorption and efficient ionization as is practiced in mass spectrometry. In CE experiment, we examined changes in a poly(ethylene oxide) (PEO) coating by continuously monitoring the electroosmotic flow (EOF) in a fused-silica capillary during electrophoresis. An imaging CCD camera was used to follow the motion of a fluorescent neutral marker zone along the length of the capillary excited by 488-nm Ar-ion laser. The PEO coating was shown to reduce the velocity of EOF by more than an order of magnitude compared to a bare capillary at pH 7.0. The coating protocol was important, especially at an intermediate pH of 7.7. The increase of p

  9. In situ surface roughness measurement using a laser scattering method

    Tay, C. J.; Wang, S. H.; Quan, C.; Shang, H. M.

    2003-03-01

    In this paper, the design and development of an optical probe for in situ measurement of surface roughness are discussed. Based on this light scattering principle, the probe which consists of a laser diode, measuring lens and a linear photodiode array, is designed to capture the scattered light from a test surface with a relatively large scattering angle ϕ (=28°). This capability increases the measuring range and enhances repeatability of the results. The coaxial arrangement that incorporates a dual-laser beam and a constant compressed air stream renders the proposed system insensitive to movement or vibration of the test surface as well as surface conditions. Tests were conducted on workpieces which were mounted on a turning machine that operates with different cutting speeds. Test specimens which underwent different machining processes and of different surface finish were also studied. The results obtained demonstrate the feasibility of surface roughness measurement using the proposed method.

  10. Laser triangulation method for measuring the size of parking claw

    Liu, Bo; Zhang, Ming; Pang, Ying

    2017-10-01

    With the development of science and technology and the maturity of measurement technology, the 3D profile measurement technology has been developed rapidly. Three dimensional measurement technology is widely used in mold manufacturing, industrial inspection, automatic processing and manufacturing, etc. There are many kinds of situations in scientific research and industrial production. It is necessary to transform the original mechanical parts into the 3D data model on the computer quickly and accurately. At present, many methods have been developed to measure the contour size, laser triangulation is one of the most widely used methods.

  11. One-step patterning of hollow microstructures in paper by laser cutting to create microfluidic analytical devices.

    Nie, Jinfang; Liang, Yuanzhi; Zhang, Yun; Le, Shangwang; Li, Dunnan; Zhang, Songbai

    2013-01-21

    In this paper, we report a simple, low-cost method for rapid, highly reproductive fabrication of paper-based microfluidics by using a commercially available, minitype CO(2) laser cutting/engraving machine. This method involves only one operation of cutting a piece of paper by laser according to a predesigned pattern. The hollow microstructures formed in the paper are used as the 'hydrophobic barriers' to define the hydrophilic flowing paths. A typical paper device on a 4 cm × 4 cm piece of paper can be fabricated within ∼7-20 s; it is ready for use once the cutting process is finished. The main fabrication parameters such as the applied current and cutting rate of the laser were optimized. The fabrication resolution and multiplexed analytical capability of the hollow microstructure-patterned paper were also characterized.

  12. Diffractive elements for generating microscale laser beam patterns: a Y2K problem

    Teiwes, Stephan; Krueger, Sven; Wernicke, Guenther K.; Ferstl, Margit

    2000-03-01

    Lasers are widely used in industrial fabrication for engraving, cutting and many other purposes. However, material processing at very small scales is still a matter of concern. Advances in diffractive optics could provide for laser systems that could be used for engraving or cutting of micro-scale patterns at high speeds. In our paper we focus on the design of diffractive elements which can be used for this special application. It is a common desire in material processing to apply 'discrete' as well as 'continuous' beam patterns. Especially, the latter case is difficult to handle as typical micro-scale patterns are characterized by bad band-limitation properties, and as speckles can easily occur in beam patterns. It is shown in this paper that a standard iterative design method usually fails to obtain diffractive elements that generate diffraction patterns with acceptable quality. Insights gained from an analysis of the design problems are used to optimize the iterative design method. We demonstrate applicability and success of our approach by the design of diffractive phase elements that generate a discrete and a continuous 'Y2K' pattern.

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

    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......-machined surfaces, normalized bearing area curves and parameters are used to characterize the surface quantitatively. The range of normalized bearing area curve parameters for plate-able surface is suggested. PBT/PET with 40 % glass fiber was used as the substrate material. For all of the studied lasers......, the parameters were varied in a relatively large range, and matrixes of the laser-machined surface were obtained. The topography of those laser-machined surfaces was examined by scanning electronic microscope (SEM). For each sample examined by SEM, there was an identical workpiece plated by for 90 min...

  14. A novel optical gating method for laser gated imaging

    Ginat, Ran; Schneider, Ron; Zohar, Eyal; Nesher, Ofer

    2013-06-01

    For the past 15 years, Elbit Systems is developing time-resolved active laser-gated imaging (LGI) systems for various applications. Traditional LGI systems are based on high sensitive gated sensors, synchronized to pulsed laser sources. Elbit propriety multi-pulse per frame method, which is being implemented in LGI systems, improves significantly the imaging quality. A significant characteristic of the LGI is its ability to penetrate a disturbing media, such as rain, haze and some fog types. Current LGI systems are based on image intensifier (II) sensors, limiting the system in spectral response, image quality, reliability and cost. A novel propriety optical gating module was developed in Elbit, untying the dependency of LGI system on II. The optical gating module is not bounded to the radiance wavelength and positioned between the system optics and the sensor. This optical gating method supports the use of conventional solid state sensors. By selecting the appropriate solid state sensor, the new LGI systems can operate at any desired wavelength. In this paper we present the new gating method characteristics, performance and its advantages over the II gating method. The use of the gated imaging systems is described in a variety of applications, including results from latest field experiments.

  15. Laboratory methods for evaluating the effect of low level laser ...

    The basic tenet of laser therapy is that laser radiation has a wavelength dependent capability to alter cellular behaviour in the absence of significant heating. Low intensity radiation can inhibit as well as stimulate cellular activity. Laser therapy typically involves the delivery of 1-4J/cm 2 to treatments sites with lasers having ...

  16. Method and system for communicating with a laser power driver

    Telford, Steven

    2017-07-18

    A system for controlling a plurality of laser diodes includes an optical transmitter coupled to the laser diode driver for each laser diode. An optical signal including bi-phase encoded data is provided to each laser diode driver. The optical signal includes current level and pulse duration information at which each of the diodes is to be driven. Upon receiving a trigger signal, the laser diode drivers operate the laser diodes using the current level and pulse duration information to output a laser beam.

  17. Laser absorption spectroscopy - Method for monitoring complex trace gas mixtures

    Green, B. D.; Steinfeld, J. I.

    1976-01-01

    A frequency stabilized CO2 laser was used for accurate determinations of the absorption coefficients of various gases in the wavelength region from 9 to 11 microns. The gases investigated were representative of the types of contaminants expected to build up in recycled atmospheres. These absorption coefficients were then used in determining the presence and amount of the gases in prepared mixtures. The effect of interferences on the minimum detectable concentration of the gases was measured. The accuracies of various methods of solution were also evaluated.

  18. Improved beam jitter control methods for high energy laser systems

    Frist, Duane C.

    2009-01-01

    Approved for public release, distribution unlimited The objective of this research was to develop beam jitter control methods for a High Energy Laser (HEL) testbed. The first step was to characterize the new HEL testbed at NPS. This included determination of natural frequencies and component models which were used to create a Matlab/Simulink model of the testbed. Adaptive filters using Filtered-X Least Mean Squares (FX-LMS) and Filtered-X Recursive Least Square (FX-RLS) were then implement...

  19. Characteristics of the Arcing Plasma Formation Effect in Spark-Assisted Chemical Engraving of Glass, Based on Machine Vision.

    Ho, Chao-Ching; Wu, Dung-Sheng

    2018-03-22

    Spark-assisted chemical engraving (SACE) is a non-traditional machining technology that is used to machine electrically non-conducting materials including glass, ceramics, and quartz. The processing accuracy, machining efficiency, and reproducibility are the key factors in the SACE process. In the present study, a machine vision method is applied to monitor and estimate the status of a SACE-drilled hole in quartz glass. During the machining of quartz glass, the spring-fed tool electrode was pre-pressured on the quartz glass surface to feed the electrode that was in contact with the machining surface of the quartz glass. In situ image acquisition and analysis of the SACE drilling processes were used to analyze the captured image of the state of the spark discharge at the tip and sidewall of the electrode. The results indicated an association between the accumulative size of the SACE-induced spark area and deepness of the hole. The results indicated that the evaluated depths of the SACE-machined holes were a proportional function of the accumulative spark size with a high degree of correlation. The study proposes an innovative computer vision-based method to estimate the deepness and status of SACE-drilled holes in real time.

  20. Characteristics of the Arcing Plasma Formation Effect in Spark-Assisted Chemical Engraving of Glass, Based on Machine Vision

    Chao-Ching Ho

    2018-03-01

    Full Text Available Spark-assisted chemical engraving (SACE is a non-traditional machining technology that is used to machine electrically non-conducting materials including glass, ceramics, and quartz. The processing accuracy, machining efficiency, and reproducibility are the key factors in the SACE process. In the present study, a machine vision method is applied to monitor and estimate the status of a SACE-drilled hole in quartz glass. During the machining of quartz glass, the spring-fed tool electrode was pre-pressured on the quartz glass surface to feed the electrode that was in contact with the machining surface of the quartz glass. In situ image acquisition and analysis of the SACE drilling processes were used to analyze the captured image of the state of the spark discharge at the tip and sidewall of the electrode. The results indicated an association between the accumulative size of the SACE-induced spark area and deepness of the hole. The results indicated that the evaluated depths of the SACE-machined holes were a proportional function of the accumulative spark size with a high degree of correlation. The study proposes an innovative computer vision-based method to estimate the deepness and status of SACE-drilled holes in real time.

  1. A compact plasma pre-ionized TEA-CO2 laser pulse clipper for material processing

    Gasmi, Taieb

    2017-08-01

    An extra-laser cavity CO2-TEA laser pulse clipper using gas breakdown techniques for high spatial resolution material processing and shallow material engraving and drilling processes is presented. Complete extinction of the nitrogen tail, that extends the pulse width, is obtained at pressures from 375 up to 1500 torr for nitrogen and argon gases. Excellent energy stability and pulse repeatability were further enhanced using high voltage assisted preionized plasma gas technique. Experimental data illustrates the direct correlation between laser pulse width and depth of engraving in aluminum and alumina materials.

  2. Root canal preparation in endodontics: conventional versus laser methods

    Goodis, Harold E.; White, Joel M.; Marshall, Sally J.; Marshall, Grayson W.; Moskowitz, Emrey

    1992-06-01

    Conventional cleaning and shaping of root canal systems employs hand and/or rotary instrumentation to remove the contents of the canal and shape the canal to receive a filling material. With the advent of the Nd:YAG laser system another method of accomplishing proper cleaning and shaping is evaluated. Single rooted teeth were radiographed bucco- lingually and mesio-distally and were divided into 2 groups. The first group was accessed and the root canal systems cleaned and shaped with a step back technique utilizing hand files and gates glidden burs. At completion of the procedure the teeth were again radiographed at the same positions as those prior to the procedure. The teeth were split longitudinally and examined under scanning electron microscopy to assess cleaning. The second group of teeth were accessed, and cleaning and shaping was accomplished using the Nd:YAG laser in combination with hand files and rotary instruments. These teeth were subjected to the same analysis as those in the first group. The before and after radiographs of each group were subjected to image analysis to determine effectiveness of the two methods in shaping the canal systems. We will discuss the ability of Nd:YAG to clean and shape root canal spaces and remove smear layer and organic tissue remnants from those areas.

  3. Laser method of acoustical emission control from vibrating surfaces

    Motyka, Zbigniew

    2013-01-01

    For limitation of the noise in environment, the necessity occurs of determining and location of sources of sounds emitted from surfaces of many machines and devices, assuring in effect the possibility of suitable constructional changes implementation, targeted at decreasing of their nuisance. In the paper, the results of tests and calculations are presented for plane surface sources emitting acoustic waves. The tests were realized with the use of scanning laser vibrometer which enabled remote registration and the spectral analysis of the surfaces vibrations. The known hybrid digital method developed for determination of sound wave emission from such surfaces divided into small finite elements was slightly modified by distinguishing the phase correlations between such vibrating elements. The final method being developed may find use in wide range of applications for different forms of vibrations of plane surfaces.

  4. Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

    Braunlich, P.F.; Tetzlaff, W.

    1989-01-01

    Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters are disclosed. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phosphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate. 34 figs

  5. Russian Portrait Engraving of the Second Half of the XVIII Century among European Schools. The Problem of Correlation with Painted Originals

    Zalina V. Tetermazova

    2012-09-01

    Full Text Available The article deals with the problem of interpretation of easel paintings in portrait engraving of the second half of the XVIII century. The national features of Russian portrait engravings development are examined on the basis of comparison with west-European works.

  6. Method of mounting a fuel pellet in a laser-excited fusion reactor

    Hirsch, R.L.

    1979-01-01

    A method is described for irradiating a target, wherein a single laser light beam from a source and a mirror close to the target are used with aperture means for directing laser light to interact with the target over a broad area of the surface, and for protecting the laser light source

  7. 2.5D direct laser engraving of silicone microfluidic channels for stretchable electronics

    Nagels, Steven; Deferme, Wim

    2017-01-01

    Stretchable and bendable sensors have become increasingly relevant as the technology behind them matures rapidly from lab based to industrially applicable production principles. In a broader sense, stretchable electronics promises to increase the way we are surrounded by and interact with our devices. Electronic circuits will be deployed in environments where we require them to dynamically flex, bend, stretch, compress, twist and - quite possibly - even fold; where they have to demonstrate a ...

  8. Laser systems configured to output a spectrally-consolidated laser beam and related methods

    Koplow, Jeffrey P [San Ramon, CA

    2012-01-10

    A laser apparatus includes a plurality of pumps each of which is configured to emit a corresponding pump laser beam having a unique peak wavelength. The laser apparatus includes a spectral beam combiner configured to combine the corresponding pump laser beams into a substantially spatially-coherent pump laser beam having a pump spectrum that includes the unique peak wavelengths, and first and second selectively reflective elements spaced from each other to define a lasing cavity including a lasing medium therein. The lasing medium generates a plurality of gain spectra responsive to absorbing the pump laser beam. Each gain spectrum corresponds to a respective one of the unique peak wavelengths of the substantially spatially-coherent pump laser beam and partially overlaps with all other ones of the gain spectra. The reflective elements are configured to promote emission of a laser beam from the lasing medium with a peak wavelength common to each gain spectrum.

  9. LDRD Final Report: Adaptive Methods for Laser Plasma Simulation

    Dorr, M R; Garaizar, F X; Hittinger, J A

    2003-01-01

    The goal of this project was to investigate the utility of parallel adaptive mesh refinement (AMR) in the simulation of laser plasma interaction (LPI). The scope of work included the development of new numerical methods and parallel implementation strategies. The primary deliverables were (1) parallel adaptive algorithms to solve a system of equations combining plasma fluid and light propagation models, (2) a research code implementing these algorithms, and (3) an analysis of the performance of parallel AMR on LPI problems. The project accomplished these objectives. New algorithms were developed for the solution of a system of equations describing LPI. These algorithms were implemented in a new research code named ALPS (Adaptive Laser Plasma Simulator) that was used to test the effectiveness of the AMR algorithms on the Laboratory's large-scale computer platforms. The details of the algorithm and the results of the numerical tests were documented in an article published in the Journal of Computational Physics [2]. A principal conclusion of this investigation is that AMR is most effective for LPI systems that are ''hydrodynamically large'', i.e., problems requiring the simulation of a large plasma volume relative to the volume occupied by the laser light. Since the plasma-only regions require less resolution than the laser light, AMR enables the use of efficient meshes for such problems. In contrast, AMR is less effective for, say, a single highly filamented beam propagating through a phase plate, since the resulting speckle pattern may be too dense to adequately separate scales with a locally refined mesh. Ultimately, the gain to be expected from the use of AMR is highly problem-dependent. One class of problems investigated in this project involved a pair of laser beams crossing in a plasma flow. Under certain conditions, energy can be transferred from one beam to the other via a resonant interaction with an ion acoustic wave in the crossing region. AMR provides an

  10. COMPARING PARTICLE SIZE DISTRIBUTION ANALYSIS BY SEDIMENTATION AND LASER DIFFRACTION METHOD

    Vito Ferro; Stefano Mirabile

    2009-01-01

    In this paper a brief review of the laser diffraction method is firstly carried out. Then, for 30 soil samples having a different texture classification sampled in Sicilian basin, a comparison between the two techniques is developed. The analysis demonstrated that the sand content measured by Sieve-Hydrometer method can be assumed equal to the one determinated by laser diffraction technique while an overestimation of the clay fraction measured by Sieve-Hydrometer method respect to laser diffr...

  11. New methods of generation of ultrashort laser pulses for ranging

    Jelinkova, Helena; Hamal, Karel; Kubecek, V.; Prochazka, Ivan

    1993-01-01

    To reach the millimeter satellite laser ranging accuracy, the goal for nineties, new laser ranging techniques have to be applied. To increase the laser ranging precision, the application of the ultrashort laser pulses in connection with the new signal detection and processing techniques, is inevitable. The two wavelength laser ranging is one of the ways to measure the atmospheric dispersion to improve the existing atmospheric correction models and hence, to increase the overall system ranging accuracy to the desired value. We are presenting a review of several nonstandard techniques of ultrashort laser pulses generation, which may be utilized for laser ranging: compression of the nanosecond pulses using stimulated Brillouin and Raman backscattering; compression of the mode-locked pulses using Raman backscattering; passive mode-locking technique with nonlinear mirror; and passive mode-locking technique with the negative feedback.

  12. Developments of integrated laser crystals by a direct bonding method

    Sugiyama, Akira; Fukuyama, Hiroyasu; Katsumata, Masaki; Tanaka, Mitsuhiro; Okada, Yukikatu

    2003-01-01

    Laser crystal integration using a neodymium-doped yttrium vanadate (or orthovanadate) laser crystal, and non-doped yttrium vanadate crystals that function as cold fingers has been demonstrated. A newly developed dry etching process was adopted in the preparation for contact of mechanically polished surfaces. In the heat treatment process, temperature optimization was essential to get rid of precipitation of vanadic acid caused by the thermo-chemical reaction in a vacuum furnace. The bonded crystal was studied via optical characteristics, magnified inspections, laser output performances pumped by a CW laser diode. From these experiments, it was clear that the integrated Nd:YVO 4 laser crystal, securing the well-improved thermal conductivity, can increase laser output power nearly twice that of the conventional single crystal which was cracked in high power laser pumping of 10 W due to its intrinsic poor thermal conductivity. (author)

  13. Laser induced desorption as hydrogen retention diagnostic method

    Zlobinski, Miroslaw

    2016-07-15

    Laser Induced Desorption Spectroscopy (LIDS) is a diagnostic method to measure the hydrogen content in the surface of a material exposed to a hydrogen isotope (H,D,T) plasma. It is developed mainly to monitor hydrogen retention in the walls of magnetic fusion devices that have to limit the amount of their fuel tritium mainly due to safety reasons. The development of fusion increasingly focusses on plasma-wall interactions for which in situ diagnostics like LIDS are required that work during plasma operation and without tile removal. The method has first been developed for thin amorphous hydrocarbon (a-C:H < 500 nm) layers successfully and is studied in the present work on thick (15 μm) layers, carbon fibre composites (CFCs), bulk tungsten (W), W fuzz and mixed C/W materials. In LID a 3 ms Nd:YAG (1064 nm) laser pulse heats a spot of diameter 3 mm with 500 {sup MW}/{sub m{sup 2}} on W to 1800 K at the surface and thus above 1300 K within ca. 0.2 mm depth. On C materials (graphite, CFC, a-C:H) this temperature guarantees a nearly complete (>95%) desorption already within 1.5 ms pulse duration. The retained hydrogen atoms are desorbed locally, recombine to molecules and migrate promptly to the surface via internal channels like pores and grain boundaries. Whereas, in W the retained hydrogen atoms have to diffuse through the bulk material, which is a relatively slow process also directed into the depth. The desorbed hydrogen fraction can thus be strongly reduced to 18-91% as observed here. This fraction is measured by melting the central part of a previously heated spot ca. 40 μm deep with a diameter 2 mm, 3 ms laser pulse, releasing the remaining hydrogen. W samples exposed to different plasmas in TEXTOR, Pilot-PSI, PSI-2, PADOS and PlaQ show that the desorption fraction of LID mainly decreases due to higher sample temperature during plasma exposure. The heat causes deeper hydrogen diffusion and/or stronger hydrogen trapping due to creation of traps with higher

  14. Laser induced desorption as hydrogen retention diagnostic method

    Zlobinski, Miroslaw

    2016-01-01

    Laser Induced Desorption Spectroscopy (LIDS) is a diagnostic method to measure the hydrogen content in the surface of a material exposed to a hydrogen isotope (H,D,T) plasma. It is developed mainly to monitor hydrogen retention in the walls of magnetic fusion devices that have to limit the amount of their fuel tritium mainly due to safety reasons. The development of fusion increasingly focusses on plasma-wall interactions for which in situ diagnostics like LIDS are required that work during plasma operation and without tile removal. The method has first been developed for thin amorphous hydrocarbon (a-C:H < 500 nm) layers successfully and is studied in the present work on thick (15 μm) layers, carbon fibre composites (CFCs), bulk tungsten (W), W fuzz and mixed C/W materials. In LID a 3 ms Nd:YAG (1064 nm) laser pulse heats a spot of diameter 3 mm with 500 MW / m 2 on W to 1800 K at the surface and thus above 1300 K within ca. 0.2 mm depth. On C materials (graphite, CFC, a-C:H) this temperature guarantees a nearly complete (>95%) desorption already within 1.5 ms pulse duration. The retained hydrogen atoms are desorbed locally, recombine to molecules and migrate promptly to the surface via internal channels like pores and grain boundaries. Whereas, in W the retained hydrogen atoms have to diffuse through the bulk material, which is a relatively slow process also directed into the depth. The desorbed hydrogen fraction can thus be strongly reduced to 18-91% as observed here. This fraction is measured by melting the central part of a previously heated spot ca. 40 μm deep with a diameter 2 mm, 3 ms laser pulse, releasing the remaining hydrogen. W samples exposed to different plasmas in TEXTOR, Pilot-PSI, PSI-2, PADOS and PlaQ show that the desorption fraction of LID mainly decreases due to higher sample temperature during plasma exposure. The heat causes deeper hydrogen diffusion and/or stronger hydrogen trapping due to creation of traps with higher binding energy

  15. A Lightweight Structure Redesign Method Based on Selective Laser Melting

    Li Tang

    2016-11-01

    Full Text Available The purpose of this paper is to present a new design method of lightweight parts fabricated by selective laser melting (SLM based on the “Skin-Frame” and to explore the influence of fabrication defects on SLM parts with different sizes. Some standard lattice parts were designed according to the Chinese GB/T 1452-2005 standard and manufactured by SLM. Then these samples were tested in an MTS Insight 30 compression testing machine to study the trends of the yield process with different structure sizes. A set of standard cylinder samples were also designed according to the Chinese GB/T 228-2010 standard. These samples, which were made of iron-nickel alloy (IN718, were also processed by SLM, and then tested in the universal material testing machine INSTRON 1346 to obtain their tensile strength. Furthermore, a lightweight redesigned method was researched. Then some common parts such as a stopper and connecting plate were redesigned using this method. These redesigned parts were fabricated and some application tests have already been performed. The compression testing results show that when the minimum structure size is larger than 1.5 mm, the mechanical characteristics will hardly be affected by process defects. The cylinder parts were fractured by the universal material testing machine at about 1069.6 MPa. These redesigned parts worked well in application tests, with both the weight and fabrication time of these parts reduced more than 20%.

  16. [Absorption spectrum of Quasi-continuous laser modulation demodulation method].

    Shao, Xin; Liu, Fu-Gui; Du, Zhen-Hui; Wang, Wei

    2014-05-01

    A software phase-locked amplifier demodulation method is proposed in order to demodulate the second harmonic (2f) signal of quasi-continuous laser wavelength modulation spectroscopy (WMS) properly, based on the analysis of its signal characteristics. By judging the effectiveness of the measurement data, filter, phase-sensitive detection, digital filtering and other processing, the method can achieve the sensitive detection of quasi-continuous signal The method was verified by using carbon dioxide detection experiments. The WMS-2f signal obtained by the software phase-locked amplifier and the high-performance phase-locked amplifier (SR844) were compared simultaneously. The results show that the Allan variance of WMS-2f signal demodulated by the software phase-locked amplifier is one order of magnitude smaller than that demodulated by SR844, corresponding two order of magnitude lower of detection limit. And it is able to solve the unlocked problem caused by the small duty cycle of quasi-continuous modulation signal, with a small signal waveform distortion.

  17. Walking response of the Mediterranean pine engraver, Orthotomicus erosus, to novel plant odors host in a laboratory olfactometer

    A. J. Walter; R. C. Venette; S. A. Kells; S. J. Seybold

    2010-01-01

    When an herbivorous insect enters a new geographic area, it will select host plants based on short and long distance cues. A conifer-feeding bark beetle that has been recently introduced to North America, the Mediterranean pine engraver, Orthotomicus erosus (Wollaston), has a potentially wide host range, especially among members of the Pinaceae....

  18. Differential susceptibility of white fir provenances to the fir engraver and its fungal symbiont in northern California

    G.T. Ferrell; W.J. Otrosina

    1996-01-01

    The fir engraver, Scolytus ventralis LeC., attacks white fir, Abies concolor (Gord. and Glend.) Lindl., and other true firs, Abies spp., in western North America. The biology, attack behavior, and ecology of this bark beetle were recently summarized by Berryman and Ferrell (1988). During the summer flight season, the attacking beetles bore into the cambial zone of...

  19. Inter- and Intrapopulation Variation of the Pheromone, Ipsdienol Produced by Male Pine Engravers Ips pini (Say) (Coleoptera: Scolytidae)

    D.R. Miller; J.H. Borden; K.N. Slessor

    1989-01-01

    We determined the chirality of ipsdienol in individual male pine engravers, Ips pini (Say), from New York, California, and two localities in British Columbia (BC). Both quantity and chirality of ipsdienol varied significantly between and within populations of I. pini . Beetles from California and southeastern BC produced...

  20. Comparison of three methods reducing the beam parameter product of a laser diode stack for long range laser illumination applications

    Lutz, Yves; Poyet, Jean-Michel; Metzger, Nicolas

    2013-10-01

    Laser diode stacks are interesting laser sources for active imaging illuminators. They allow the accumulation of large amounts of energy in multi-pulse mode, which is well suited for long-range image recording. Even when laser diode stacks are equipped with fast-axis collimation (FAC) and slow-axis collimation (SAC) microlenses, their beam parameter product (BPP) are not compatible with a direct use in highly efficient and compact illuminators. This is particularly true when narrow divergences are required such as for long range applications. To overcome these difficulties, we conducted investigations in three different ways. A first near infrared illuminator based on the use of conductively cooled mini-bars was designed, realized and successfully tested during outdoor experimentations. This custom specified stack was then replaced in a second step by an off-the-shelf FAC + SAC micro lensed stack where the brightness was increased by polarization overlapping. The third method still based on a commercial laser diode stack uses a non imaging optical shaping principle resulting in a virtually restacked laser source with enhanced beam parameters. This low cost, efficient and low alignment sensitivity beam shaping method allows obtaining a compact and high performance laser diode illuminator for long range active imaging applications. The three methods are presented and compared in this paper.

  1. Development and application of preventive maintenance technique for pipes using laser cladding method

    Hatakenaka, Hiroaki; Yamadera, Masao; Shiraiwa, Takanori.

    1995-01-01

    A laser cladding method which produces a highly corrosion-resisting coating (cladding) on the surface of the material was developed for the purpose of preventing stress corrosion cracking (SCC) in the austenitic stainless steel (Type 304). In this method, metallic powder paste is applied on the inner surface of pipes, and then a YAG laser beam is irradiated to the paste, which melts and forms a clad with excellent corrosion resistance. Recently, the laser cladding method was practically and successfully applied to the actual nuclear power plant in Japan. This report describes this laser cladding technique, the equipment, and actual works in the field. (author)

  2. Target isolation system, high power laser and laser peening method and system using same

    Dane, C. Brent; Hackel, Lloyd A.; Harris, Fritz

    2007-11-06

    A system for applying a laser beam to work pieces, includes a laser system producing a high power output beam. Target delivery optics are arranged to deliver the output beam to a target work piece. A relay telescope having a telescope focal point is placed in the beam path between the laser system and the target delivery optics. The relay telescope relays an image between an image location near the output of the laser system and an image location near the target delivery optics. A baffle is placed at the telescope focal point between the target delivery optics and the laser system to block reflections from the target in the target delivery optics from returning to the laser system and causing damage.

  3. Laser spectroscopy: Assessment of research needs for laser technologies applied to advanced spectroscopic methods

    Hurst, G.S.

    1990-05-01

    This report is organized as follows. Section 2 summarizes the current program of DOE's Office of Health and Environmental Research (OHER) and provides some remarks on low laser science and technology could beneficially impact most of the research programs. Section 3 provides a brief global perspective on laser technology and attempts to define important trends in the field. Similarly, Section 4 provides a global perspective on laser spectroscopy and addresses important trends. Thus, Section 5 focuses on the trends in laser technology and spectroscopy which could impact the OHER mission in significant ways and contains the basis for recommendations made in the executive summary. For those with limited familiarity with laser technology and laser spectroscopy, reference is made to Appendix 1 for a list of abbreviations and acronyms. Appendix 2 can serve a useful review or tutorial for those who are not deeply involved with laser spectroscopy. Even those familiar with laser spectroscopy and laser technology may find it useful to know precisely what the authors of this document mean by certain specialized terms and expressions. Finally, a note on the style of referencing may be appropriate. Whenever possible a book or review articles is referenced as the preferred citation. However, we frequently found it useful to reference a number of individual papers of recent origin or those which were not conveniently found in the review articles

  4. Assessing the significance of Palaeolithic engraved cortexes. A case study from the Mousterian site of Kiik-Koba, Crimea.

    Ana Majkić

    Full Text Available Twenty-Seven Lower and Middle Paleolithic sites from Europe and the Middle East are reported in the literature to have yielded incised stones. At eleven of these sites incisions are present on flint cortexes. Even when it is possible to demonstrate that the engravings are ancient and human made, it is often difficult to distinguish incisions resulting from functional activities such as butchery or use as a cutting board, from those produced deliberately, and even more difficult to identify the scope of the latter. In this paper we present results of the analysis of an engraved cortical flint flake found at Kiik-Koba, a key Mousterian site from Crimea, and create an interpretative framework to guide the interpretation of incised cortexes. The frame of inference that we propose allows for a reasoned evaluation of the actions playing a role in the marking process and aims at narrowing down the interpretation of the evidence. The object comes from layer IV, the same layer in which a Neanderthal child burial was unearthed, which contains a para-Micoquian industry of Kiik-Koba type dated to between c.35 and 37 cal kyr BP. The microscopic analysis and 3D reconstruction of the grooves on the cortex of this small flint flake, demonstrate that the incisions represent a deliberate engraving made by a skilled craftsman, probably with two different points. The lines are nearly perfectly framed into the cortex, testifying of well controlled motions. This is especially the case considering the small size of the object, which makes this a difficult task. The production of the engraving required excellent neuromotor and volitional control, which implies focused attention. Evaluation of the Kiik-Koba evidence in the light of the proposed interpretative framework supports the view that the engraving was made with a representational intent.

  5. Gas discharge laser and method of manufacturing same

    Haans, P.F.A.

    1975-01-01

    On a thick-walled capillary tube rounded edges are pressed at either end. Double-conical surfaces are ground on the rounded edges so that a fitting edge which is very obtuse in cross-section is obtained for laser mirrors of a He-Ne laser of an economic construction

  6. Method and apparatus for laser-controlled proton beam radiology

    Johnstone, Carol J.

    1998-01-01

    A proton beam radiology system provides cancer treatment and proton radiography. The system includes an accelerator for producing an H.sup.- beam and a laser source for generating a laser beam. A photodetachment module is located proximate the periphery of the accelerator. The photodetachment module combines the H.sup.- beam and laser beam to produce a neutral beam therefrom within a subsection of the H.sup.- beam. The photodetachment module emits the neutral beam along a trajectory defined by the laser beam. The photodetachment module includes a stripping foil which forms a proton beam from the neutral beam. The proton beam is delivered to a conveyance segment which transports the proton beam to a patient treatment station. The photodetachment module further includes a laser scanner which moves the laser beam along a path transverse to the cross-section of the H.sup.- beam in order to form the neutral beam in subsections of the H.sup.- beam. As the scanning laser moves across the H.sup.- beam, it similarly varies the trajectory of the proton beam emitted from the photodetachment module and in turn varies the target location of the proton beam upon the patient. Intensity modulation of the proton beam can also be achieved by controlling the output of the laser.

  7. Method of concentrating and separating lithium isotopes by laser

    Yamashita, Mikio; Kashiwagi, Hiroshi.

    1976-01-01

    Purpose: To eliminate the need for repeating separating operation in many stages and permit concentrated lithium of high purity to be obtained in a short period of time. Constitution: Lithium atom vapor is irradiated by a laser of wavelengths resonant to 6 Li or 7 Li absorption spectra present in the neighborhood of 6,707.84 A or 3,232.61 A (chromatic laser being used for oscillation in the neighborhood of 6,707.84 A and ultraviolet laser used for oscillation in the neighborhood of 6,707.84 A) for selectively exciting 6 Li or 7 Li alone. Then, ionization is brought about by using other types of lasers (ultraviolet Ar ion laser being used as the former wavelength laser and visible Ar ion laser as the latter wavelength laser), and only the ionized isotopes are passed through a mass filter and collected by an ion collector, thereby effecting separation of the ionized isotopes from the non-ionized neutral isotopes and their concentration. (Aizawa, K.)

  8. The Effect of Laser Treatment as a Weed Control Method

    Mathiassen, Solvejg K; Bak, Thomas; Christensen, Svend

    2006-01-01

    at the cotyledon stage. Experiments were carried out under controlled conditions, using pot-grown weeds. Two lasers and two spot sizes were tested and different energy doses were applied by varying the exposure time. The biological efficacy was examined on three different weed species: Stellaria media (common...... was related to wavelength, exposure time, spot size and laser power. The efficacy also varied between the weed species. The results indicate that the efficacy of laser treatments can be improved by a more precise pointing of the laser beam towards the apical meristems and optimisation of the energy density...... (exposure time and spot size of the laser beam). The experiment also showed a significant difference between two wavelengths. In order to improve the performance and to validate the efficacy on a broader spectrum of weed species, further research and development is needed....

  9. Study on effective laser cleaning method to remove carbon layer from a gold surface

    Singh, Amol; Modi, Mohammed H; Lodha, G S; Choubey, A K; Upadhyaya, B N

    2013-01-01

    Hydrocarbon cracking and carbon contamination is a common problem in soft x-ray Synchrotron Radiation (SR) beamlines. Carbon contamination on optics is known to absorb and scatter radiation close to the C K-edge (284 eV) spectral region. The purpose of this work is to study and develop a laser cleaning method that can effectively remove the carbon contaminations without damaging the underneath gold-coated optics. The laser cleaning process is a non-contact, accurate, efficient and safe. Nd:YAG laser of 100 ns pulse duration is used for carbon cleaning. The effect of laser pulse duration, laser fluence, number of laser passes, angle of incidence and spot overlapping on the cleaning performance is studied. Cleaning effect and subsequent film quality after laser irradiation is analyzed using x-ray photoelectron spectroscopy (XPS) and soft x-ray reflectivity (SXR) techniques.

  10. Restoration and Preservation of Engraved Limestone Blocks Discovered in Abu Mousa Excavation, Suez - Egypt

    Nabil A. Abd El-Tawab BADER

    2013-03-01

    Full Text Available A lot of engraved limestone blocks were discovered at Awlad Abu Musa (east of Suez, Egypt in 1995/2007 by Supreme Council of Antiquities. The stone blocks were seriously affected by archaeological environments during burial environment in agriculture land. They were covered with thick clay layer with soil particles that disfigured them and hid their inscriptions. Prior to the conservation intervention, the materials were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, Chemical analyses of ground water and microbiological study. After the material characterization, the conservation and restoration of the stone blocks were carried out including cleaning, consolidation, reduction of salts, Re-jointing, restoration and completion of lost parts. After that the blocks were exhibited in Suez museum.

  11. More than horse paintings in Ekain Cave (Deba, Gipuzkoa: Palaeolithic digital engravings in Western Europe

    Blanca Ochoa

    2018-06-01

    Full Text Available Technological advances are enabling the discovery of new caves with rock art and of new graphic units in already known and studied caves. In this framework, a discovery was made in an unexplored gallery in Ekain (Deba, Gipuzkoa, a small passage named La Fontana. Figurative representations (horses and non-figurative marks (simple strokes were traced on both walls using digital engraving on decalcified clay. This discovery prompted the re-study of depictions executed with the same technique in the final part of Azkenzaldei gallery, where a new ensemble of representations, mostly non-figurative, was also found. Since it is impossible to date these representations directly, we apply a stylistic analysis to establish their chronology. The comparison with other depictions in the same cave might point towards their execution during advanced phases of the Magdalenian.

  12. Laser induced ultrasonic phased array using full matrix capture data acquisition and total focusing method.

    Stratoudaki, Theodosia; Clark, Matt; Wilcox, Paul D

    2016-09-19

    Laser ultrasonics is a technique where lasers are employed to generate and detect ultrasound. A data collection method (full matrix capture) and a post processing imaging algorithm, the total focusing method, both developed for ultrasonic arrays, are modified and used in order to enhance the capabilities of laser ultrasonics for nondestructive testing by improving defect detectability and increasing spatial resolution. In this way, a laser induced ultrasonic phased array is synthesized. A model is developed and compared with experimental results from aluminum samples with side drilled holes and slots at depths of 5 - 20 mm from the surface.

  13. Comparative evaluation of skin cancer therapy with impulse laser radiation and surgical methods

    Moskalik, K.G.; Kozlov, A.P.

    1980-01-01

    Altogether 324 patients with skin basilomas, 559 with recurrent basiloma and 38 with squamous-cell carcinoma of the skin were treated by means of impulse neodymium laser radiation. A follow-up period was up to 7 years. It was shown that impulse laser radiation is a highly effective means of treating skin cancer, having a number of advantages over the radiation and surgical methods. Laser radiation is also highly effective in the treatment of basiloma relapses. If relapses accounted for by the development of a radioresistant tumour occur at the sites where surgical eXcision yields an unstatisfactory cosmetic effect, laser therapy should be considered a method of choice

  14. Laser-driven ion acceleration: methods, challenges and prospects

    Badziak, J.

    2018-01-01

    The recent development of laser technology has resulted in the construction of short-pulse lasers capable of generating fs light pulses with PW powers and intensities exceeding 1021 W/cm2, and has laid the basis for the multi-PW lasers, just being built in Europe, that will produce fs pulses of ultra-relativistic intensities ~ 1023 - 1024 W/cm2. The interaction of such an intense laser pulse with a dense target can result in the generation of collimated beams of ions of multi-MeV to GeV energies of sub-ps time durations and of extremely high beam intensities and ion fluencies, barely attainable with conventional RF-driven accelerators. Ion beams with such unique features have the potential for application in various fields of scientific research as well as in medical and technological developments. This paper provides a brief review of state-of-the art in laser-driven ion acceleration, with a focus on basic ion acceleration mechanisms and the production of ultra-intense ion beams. The challenges facing laser-driven ion acceleration studies, in particular those connected with potential applications of laser-accelerated ion beams, are also discussed.

  15. Laser therapy and comparative therapy methods in parodontology

    Schauer, P

    1997-02-01

    This two studies aim to examine application of a diode-laser in periodontal therapy. The aim of the pilot-study was to examine the immediate effect of the diode-laser in reducing the bacterial concentration in periodontal pockets. 50 patients were randomly subdivided into two groups (laser group, control group) and microbiologic samples were collected. One week after the therapy (1 st group: scaling and laser, 2 nd group: scaling) there were taken further more samples from the same periodontal pockets treated before. The microbiologic samples were evaluated to verify bacterial elimination from the periodontal pockets, especially Actinobacillus actinomycetemcomitans could be considerably eliminated from periodontal pockets by the diode laser. In the long-term study, there were two groups, one laser-group and one control-group. All 50 patients were required to have periodontal pockets with a minimum depth of 4 mm in each quadrate. The bacterial reduction, the change of bleeding on probing and the pocket depth had been evaluated six months after therapy. The irradiation with the diode laser allows considerable bacterial elimination, the index of bleeding on probing came out to be significantly better than in the control group. The reduction of pocket depth was also greater than in the control group. (author)

  16. Research on atmospheric transmission distortion of Gauss laser using multiple phase screen method

    Zhang, Yizhuo; Wang, Qiushi; Gu, Haidong

    2018-02-01

    The laser beam is attenuated, broadened, defocused and may even be deflected from its initial propagation direction as it propagates through the atmosphere. It leads to the decrease of the laser intensity of the receiving surface. Gauss beam is the fundamental components of all possible laser waveforms. Therefore, research on the transmission of the Gauss laser has far-reaching consequences in optical communication, weaponry, target designation, ranging, remote sensing and other applications that require transmission of laser beams through the atmosphere. In this paper, we propose a laboratory simulation method using multi-phase screen to calculate the effects of atmospheric turbulence. Theoretical analysis of Gauss laser transmission in the atmosphere is given. By calculating the propagation of the Gauss beam TEM00, the far field intensity and phase distribution is shown. By the given method, the optical setup is presented and used for optimizing the adaptive optics algorithm.

  17. Ultrafast laser based coherent control methods for explosives detection

    Moore, David Steven [Los Alamos National Laboratory

    2010-12-06

    The detection of explosives is a notoriously difficult problem, especially at stand-off, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring Optimal Dynamic Detection of Explosives (ODD-Ex), which exploits the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity to explosives signatures while dramatically improving specificity, particularly against matrix materials and background interferences. These goals are being addressed by operating in an optimal non-linear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe subpulses. Recent results will be presented.

  18. Advanced methods for nuclear reactor gas laser coupling

    Miley, G.H.; Verdeyen, J.T.

    1978-06-01

    Research is described that led to the discovery of three nuclear-pumped lasers (NPLs) using mixtures of Ne--N 2 , He--Hg, and He or Ne with CO or CO 2 . The Ne--N 2 NPL was the first laser obtained with modest neutron fluxes from a TRIGA reactor (vs fast burst reactors used elsewhere in such work), the He--Hg NPL was the first visible nuclear-pumped laser, while the Ne--CO and He--CO 2 lasers are the first to provide energy storage on a millisecond time scale. Important potential applications of NPLs include coupling and power transmission from remote power stations such as nuclear plants in satellites and neutron-feedback operation of inertial confinement fusion plants

  19. Method and system for compact efficient laser architecture

    Bayramian, Andrew James; Erlandson, Alvin Charles; Manes, Kenneth Rene; Spaeth, Mary Louis; Caird, John Allyn; Deri, Robert J.

    2015-09-15

    A laser amplifier module having an enclosure includes an input window, a mirror optically coupled to the input window and disposed in a first plane, and a first amplifier head disposed along an optical amplification path adjacent a first end of the enclosure. The laser amplifier module also includes a second amplifier head disposed along the optical amplification path adjacent a second end of the enclosure and a cavity mirror disposed along the optical amplification path.

  20. COMPARING PARTICLE SIZE DISTRIBUTION ANALYSIS BY SEDIMENTATION AND LASER DIFFRACTION METHOD

    Vito Ferro

    2009-06-01

    Full Text Available In this paper a brief review of the laser diffraction method is firstly carried out. Then, for 30 soil samples having a different texture classification sampled in Sicilian basin, a comparison between the two techniques is developed. The analysis demonstrated that the sand content measured by Sieve-Hydrometer method can be assumed equal to the one determinated by laser diffraction technique while an overestimation of the clay fraction measured by Sieve-Hydrometer method respect to laser diffraction technique was obtained. Finally a set of equations useful to refer LD measurements to SH method was proposed.

  1. Automatic Tree Data Removal Method for Topography Measurement Result Using Terrestrial Laser Scanner

    Yokoyama, H.; Chikatsu, H.

    2017-02-01

    Recently, laser scanning has been receiving greater attention as a useful tool for real-time 3D data acquisition, and various applications such as city modelling, DTM generation and 3D modelling of cultural heritage sites have been proposed. And, former digital data processing were demanded in the past digital archive techniques for cultural heritage sites. However, robust filtering method for distinguishing on- and off-terrain points by terrestrial laser scanner still have many issues. In the past investigation, former digital data processing using air-bone laser scanner were reported. Though, efficient tree removal methods from terrain points for the cultural heritage are not considered. In this paper, authors describe a new robust filtering method for cultural heritage using terrestrial laser scanner with "the echo digital processing technology" as latest data processing techniques of terrestrial laser scanner.

  2. Laser capture microdissection: Arcturus(XT) infrared capture and UV cutting methods.

    Gallagher, Rosa I; Blakely, Steven R; Liotta, Lance A; Espina, Virginia

    2012-01-01

    Laser capture microdissection (LCM) is a technique that allows the precise procurement of enriched cell populations from a heterogeneous tissue under direct microscopic visualization. LCM can be used to harvest the cells of interest directly or can be used to isolate specific cells by ablating the unwanted cells, resulting in histologically enriched cell populations. The fundamental components of laser microdissection technology are (a) visualization of the cells of interest via microscopy, (b) transfer of laser energy to a thermolabile polymer with either the formation of a polymer-cell composite (capture method) or transfer of laser energy via an ultraviolet laser to photovolatize a region of tissue (cutting method), and (c) removal of cells of interest from the heterogeneous tissue section. Laser energy supplied by LCM instruments can be infrared (810 nm) or ultraviolet (355 nm). Infrared lasers melt thermolabile polymers for cell capture, whereas ultraviolet lasers ablate cells for either removal of unwanted cells or excision of a defined area of cells. LCM technology is applicable to an array of applications including mass spectrometry, DNA genotyping and loss-of-heterozygosity analysis, RNA transcript profiling, cDNA library generation, proteomics discovery, and signal kinase pathway profiling. This chapter describes the unique features of the Arcturus(XT) laser capture microdissection instrument, which incorporates both infrared capture and ultraviolet cutting technology in one instrument, using a proteomic downstream assay as a model.

  3. Forecasting method in multilateration accuracy based on laser tracker measurement

    Aguado, Sergio; Santolaria, Jorge; Samper, David; José Aguilar, Juan

    2017-01-01

    Multilateration based on a laser tracker (LT) requires the measurement of a set of points from three or more positions. Although the LTs’ angular information is not used, multilateration produces a volume of measurement uncertainty. This paper presents two new coefficients from which to determine whether the measurement of a set of points, before performing the necessary measurements, will improve or worsen the accuracy of the multilateration results, avoiding unnecessary measurement, and reducing the time and economic cost required. The first specific coefficient measurement coefficient (MC LT ) is unique for each laser tracker. It determines the relationship between the radial and angular laser tracker measurement noise. Similarly, the second coefficient is related with specific conditions of measurement β . It is related with the spatial angle between the laser tracker positions α and its effect on error reduction. Both parameters MC LT and β are linked in error reduction limits. Beside these, a new methodology to determine the multilateration reduction limit according to the multilateration technique of an ideal laser tracker distribution and a random one are presented. It provides general rules and advice from synthetic tests that are validated through a real test carried out in a coordinate measurement machine. (paper)

  4. Roll-to-Roll Nanoforming of Metals Using Laser-Induced Superplasticity.

    Goswami, Debkalpa; Munera, Juan C; Pal, Aniket; Sadri, Behnam; Scarpetti, Caio Lui P G; Martinez, Ramses V

    2018-05-24

    This Letter describes a low-cost, scalable nanomanufacturing process that enables the continuous forming of thin metallic layers with nanoscale accuracy using roll-to-roll, laser-induced superplasticity (R2RLIS). R2RLIS uses a laser shock to induce the ultrahigh-strain-rate deformation of metallic films at room temperature into low-cost polymeric nanomolds, independently of the original grain size of the metal. This simple and inexpensive nanoforming method does not require access to cleanrooms and associated facilities, and can be easily implemented on conventional CO 2 lasers, enabling laser systems commonly used for rapid prototyping or industrial cutting and engraving to fabricate uniform and three-dimensional crystalline metallic nanostructures over large areas. Tuning the laser power during the R2RLIS process enables the control of the aspect ratio and the mechanical and optical properties of the fabricated nanostructures. This roll-to-roll technique successfully fabricates mechanically strengthened gold plasmonic nanostructures with aspect ratios as high as 5 that exhibit high oxidation resistance and strong optical field enhancements. The CO 2 laser used in R2RLIS can also integrate the fabricated nanostructures on transparent flexible substrates with robust interfacial contact. The ability to fabricate ultrasmooth metallic nanostructures using roll-to-roll manufacturing enables the large scale production, at a relatively low-cost, of flexible plasmonic devices toward emerging applications.

  5. Optimization of Paper Discoloration via Pyrolysis Using Lasers

    Alhashem, Mayadah M.

    2017-04-01

    Printing ink is a main component of the modern printer, and it has always been throughout the history of printing. Ink and toners are expensive replaceable components that inkjet and laser printers cannot function without. The digital printing industry, which is majorly composed of monochrome printing, is expected to increase by 225% by 2024 from a 2013 baseline (Smithers et al., 2014). Expenses aside, toner cartridges and ink cartridges pose an overlooked threat to the environment. Manufacturing, packaging, transporting, and waste disposal of printer ink and toners result in carbon dioxide emissions. The complete elimination of ink in monochrome printing is potentially viable with the patented new discoloration technique. The patent studies a discoloration method by carbonizing a paper’s surface (Alhashem et al., 2015). The printing method optimizes surface paper pyrolysis via laser heating. The aim is obtaining the darkest possible shade without compromising paper quality. The challenge is in creating a printed area from the paper material itself, rather than depositing ink on paper. A 75-watt CO2 laser engraving machine emitting a 10.6 μm wavelength beam for heating is used with low power settings to carbonize a fraction of the paper surface. The carbonization is essentially a combustion reaction. Solid fuel burns in three stages: drying, devolatilization (pyrolysis, or distillation phase), and lastly, the char (charcoal) combustion. These stages are driven by heat from the CO2 laser. Moving the laser rapidly above the paper surface arrests the reaction at the second stage, after the formation of blackened char. The control variables in the experimental method are laser power, speed, and the vertical position that affects the laser intensity. Computer software controls these variables. The discoloration of paper is quantified by measuring the light absorptivity using a UV-Vis-IR Spectrometer.

  6. FDTD method for laser absorption in metals for large scale problems.

    Deng, Chun; Ki, Hyungson

    2013-10-21

    The FDTD method has been successfully used for many electromagnetic problems, but its application to laser material processing has been limited because even a several-millimeter domain requires a prohibitively large number of grids. In this article, we present a novel FDTD method for simulating large-scale laser beam absorption problems, especially for metals, by enlarging laser wavelength while maintaining the material's reflection characteristics. For validation purposes, the proposed method has been tested with in-house FDTD codes to simulate p-, s-, and circularly polarized 1.06 μm irradiation on Fe and Sn targets, and the simulation results are in good agreement with theoretical predictions.

  7. Methods and Devices for Space Optical Communications Using Laser Beams

    Goorjian, Peter M. (Inventor)

    2018-01-01

    Light is used to communicate between objects separated by a large distance. Light beams are received in a telescopic lens assembly positioned in front of a cat's-eye lens. The light can thereby be received at various angles to be output by the cat's-eye lens to a focal plane of the cat's-eye lens, the position of the light beams upon the focal plane corresponding to the angle of the beam received. Lasers and photodetectors are distributed along this focal plane. A processor receives signals from the photodetectors, and selectively signal lasers positioned proximate the photodetectors detecting light, in order to transmit light encoding data through the cat's-eye lens and also through a telescopic lens back in the direction of the received light beams, which direction corresponds to a location upon the focal plane of the transmitting lasers.

  8. Calibration method for a vision guiding-based laser-tracking measurement system

    Shao, Mingwei; Wei, Zhenzhong; Hu, Mengjie; Zhang, Guangjun

    2015-01-01

    Laser-tracking measurement systems (laser trackers) based on a vision-guiding device are widely used in industrial fields, and their calibration is important. As conventional methods typically have many disadvantages, such as difficult machining of the target and overdependence on the retroreflector, a novel calibration method is presented in this paper. The retroreflector, which is necessary in the normal calibration method, is unnecessary in our approach. As the laser beam is linear, points on the beam can be obtained with the help of a normal planar target. In this way, we can determine the function of a laser beam under the camera coordinate system, while its corresponding function under the laser-tracker coordinate system can be obtained from the encoder of the laser tracker. Clearly, when several groups of functions are confirmed, the rotation matrix can be solved from the direction vectors of the laser beams in different coordinate systems. As the intersection of the laser beams is the origin of the laser-tracker coordinate system, the translation matrix can also be determined. Our proposed method not only achieves the calibration of a single laser-tracking measurement system but also provides a reference for the calibration of a multistation system. Simulations to evaluate the effects of some critical factors were conducted. These simulations show the robustness and accuracy of our method. In real experiments, the root mean square error of the calibration result reached 1.46 mm within a range of 10 m, even though the vision-guiding device focuses on a point approximately 5 m away from the origin of its coordinate system, with a field of view of approximately 200 mm  ×  200 mm. (paper)

  9. Gas laser tube and method of fabricating same

    Garman, L.E.

    1975-01-01

    An improved gas laser tube is fabricated by counter boring the ends of a tubular aluminum extrusion having an inner tubular portion supported from an outer tubular portion via the intermediary of a plurality of radially directed support vanes or legs. Metallic transverse walls are sealed across the ends of the tubular extrusion to define the ends of a gas tight metallic envelope. An electrically insulative glow discharge tube is axially disposed within and supported by the inner tubular portion of the extrusion in axial alignment with an optical resonator of the laser tube. (U.S.)

  10. System and method for laser assisted sample transfer to solution for chemical analysis

    Van Berkel, Gary J; Kertesz, Vilmos

    2014-01-28

    A system and method for laser desorption of an analyte from a specimen and capturing of the analyte in a suspended solvent to form a testing solution are described. The method can include providing a specimen supported by a desorption region of a specimen stage and desorbing an analyte from a target site of the specimen with a laser beam centered at a radiation wavelength (.lamda.). The desorption region is transparent to the radiation wavelength (.lamda.) and the sampling probe and a laser source emitting the laser beam are on opposite sides of a primary surface of the specimen stage. The system can also be arranged where the laser source and the sampling probe are on the same side of a primary surface of the specimen stage. The testing solution can then be analyzed using an analytical instrument or undergo further processing.

  11. Comparison of infrared laser beam shaping by diffractive and refractive methods

    Forbes, A

    2005-08-01

    Full Text Available Infra-red laser beam shaping has the inherent difficulty that simple ray tracing methods often yield anomalous results, due primarily to the propagation effects at longer wavelengths. Techniques based on diffraction theory have been developed...

  12. Standardization of Laser Methods and Techniques for Vibration Measurements and Calibrations

    Martens, Hans-Juergen von

    2010-01-01

    The realization and dissemination of the SI units of motion quantities (vibration and shock) have been based on laser interferometer methods specified in international documentary standards. New and refined laser methods and techniques developed by national metrology institutes and by leading manufacturers in the past two decades have been swiftly specified as standard methods for inclusion into in the series ISO 16063 of international documentary standards. A survey of ISO Standards for the calibration of vibration and shock transducers demonstrates the extended ranges and improved accuracy (measurement uncertainty) of laser methods and techniques for vibration and shock measurements and calibrations. The first standard for the calibration of laser vibrometers by laser interferometry or by a reference accelerometer calibrated by laser interferometry (ISO 16063-41) is on the stage of a Draft International Standard (DIS) and may be issued by the end of 2010. The standard methods with refined techniques proved to achieve wider measurement ranges and smaller measurement uncertainties than that specified in the ISO Standards. The applicability of different standardized interferometer methods to vibrations at high frequencies was recently demonstrated up to 347 kHz (acceleration amplitudes up to 350 km/s 2 ). The relative deviations between the amplitude measurement results of the different interferometer methods that were applied simultaneously, differed by less than 1% in all cases.

  13. An Improved Method of Mitigating Laser Induced Surface Damage Growth in Fused Silica Using a Rastered, Pulsed CO2 Laser

    Bass, I L; Guss, G M; Nostrand, M J; Wegner, P L

    2010-10-21

    A new method of mitigating (arresting) the growth of large (>200 m diameter and depth) laser induced surface damage on fused silica has been developed that successfully addresses several issues encountered with our previously-reported large site mitigation technique. As in the previous work, a tightly-focused 10.6 {micro}m CO{sub 2} laser spot is scanned over the damage site by galvanometer steering mirrors. In contrast to the previous work, the laser is pulsed instead of CW, with the pulse length and repetition frequency chosen to allow substantial cooling between pulses. This cooling has the important effect of reducing the heat-affected zone capable of supporting thermo-capillary flow from scale lengths on the order of the overall scan pattern to scale lengths on the order of the focused laser spot, thus preventing the formation of a raised rim around the final mitigation site and its consequent down-stream intensification. Other advantages of the new method include lower residual stresses, and improved damage threshold associated with reduced amounts of redeposited material. The raster patterns can be designed to produce specific shapes of the mitigation pit including cones and pyramids. Details of the new technique and its comparison with the previous technique will be presented.

  14. Localized corrosion evaluation of the ASTM F139 stainless steel marked by laser using scanning vibrating electrode technique, X-ray photoelectron spectroscopy and Mott–Schottky techniques

    Pieretti, Eurico F.; Manhabosco, Sara M.; Dick, Luís F.P.; Hinder, Steve; Costa, Isolda

    2014-01-01

    Graphical abstract: SEM image of pits found at the centred marked area, where the laser beam focused twice. - Highlights: • The effect of laser engraving on the corrosion resistance of the ASTM F139 was studied. • Scanning vibrating electrode technique was used to identify the anodic zone. • Laser engraving of austenitic stainless steels produces highly defective surfaces. • Laser engraving causes large chemical modification of the surface. • Pitting nucleates at the interface between laser affected and unaffected areas. - Abstract: The effect of laser engraving on the corrosion resistance of ASTM F139 stainless steel (SS) has been investigated by electrochemical techniques. The nucleation of localized corrosion on this biomaterial was evaluated by scanning vibrating electrode technique (SVET) in a phosphate buffered saline solution (PBS) of pH 7.4. The Mott–Schottky approach was used to determine the electronic properties of the passive film, also chemically characterized by X-ray photoelectron spectroscopy (XPS). SVET allowed the identification of the anodic zones on the surface of the SS marked by laser technique that were associated with the heat-affected areas. Metallic drops solidified on the laser marked surface dissolved actively at OCP and favoured the nucleation of crevice corrosion, while at the pitting potential, pits nucleate preferentially on the laser marks. XPS results showed that laser engraving caused large chemical modification of the surface. Mott–Schottky results indicated a more defective oxide layer with a larger number of donors on the laser marked surface comparatively to that without marks

  15. Deformation measurements of materials at low temperatures using laser speckle photography method

    Sumio Nakahara; Yukihide Maeda; Kazunori Matsumura; Shigeyoshi Hisada; Takeyoshi Fujita; Kiyoshi Sugihara

    1992-01-01

    The authors observed deformations of several materials during cooling down process from room temperature to liquid nitrogen temperature using the laser speckle photography method. The in-plane displacements were measured by the image plane speckle photography and the out-of-plane displacement gradients by the defocused speckle photography. The results of measurements of in-plane displacement are compared with those of FEM analysis. The applicability of laser speckle photography method to cryogenic engineering are also discussed

  16. Lasers

    Milonni, Peter W

    1988-01-01

    A comprehensive introduction to the operating principles and applications of lasers. Explains basic principles, including the necessary elements of classical and quantum physics. Provides concise discussions of various laser types including gas, solid state, semiconductor, and free electron lasers, as well as of laser resonators, diffraction, optical coherence, and many applications including holography, phase conjugation, wave mixing, and nonlinear optics. Incorporates many intuitive explanations and practical examples. Discussions are self-contained in a consistent notation and in a style that should appeal to physicists, chemists, optical scientists and engineers.

  17. Method and system for homogenizing diode laser pump arrays

    Bayramian, Andy J

    2013-10-01

    An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.

  18. Laser materials development by means of a solid-state bonding method

    Sugiyama, Akira

    2011-01-01

    This paper reviews laser materials development via a bonding method without adhesives. Instead of conventional chemical etching, a dry etching technique using an argon beam has been newly developed for the bonding method. This method meets the requirement for the use of optical materials. We succeeded in the fabrication of a composite laser crystal with good heat conductivity by bonding two kinds of crystals; one is neodymium-doped YVO 4 crystal (Nd:YVO 4 ) and the other is its host crystal YVO 4 . In the comparison of the laser performance between the normal and composite crystal, the composite one shows the good lasing capability of increasing laser output without fracture of the crystal due to thermal stress which appeared in the normal one. (author)

  19. Soil Particle Size Analysis by Laser Diffractometry: Result Comparison with Pipette Method

    Šinkovičová, Miroslava; Igaz, Dušan; Kondrlová, Elena; Jarošová, Miriam

    2017-10-01

    Soil texture as the basic soil physical property provides a basic information on the soil grain size distribution as well as grain size fraction representation. Currently, there are several methods of particle dimension measurement available that are based on different physical principles. Pipette method based on the different sedimentation velocity of particles with different diameter is considered to be one of the standard methods of individual grain size fraction distribution determination. Following the technical advancement, optical methods such as laser diffraction can be also used nowadays for grain size distribution determination in the soil. According to the literature review of domestic as well as international sources related to this topic, it is obvious that the results obtained by laser diffractometry do not correspond with the results obtained by pipette method. The main aim of this paper was to analyse 132 samples of medium fine soil, taken from the Nitra River catchment in Slovakia, from depths of 15-20 cm and 40-45 cm, respectively, using laser analysers: ANALYSETTE 22 MicroTec plus (Fritsch GmbH) and Mastersizer 2000 (Malvern Instruments Ltd). The results obtained by laser diffractometry were compared with pipette method and the regression relationships using linear, exponential, power and polynomial trend were derived. Regressions with the three highest regression coefficients (R2) were further investigated. The fit with the highest tightness was observed for the polynomial regression. In view of the results obtained, we recommend using the estimate of the representation of the clay fraction (analysis is done according to laser diffractometry. The advantages of laser diffraction method comprise the short analysis time, usage of small sample amount, application for the various grain size fraction and soil type classification systems, and a wide range of determined fractions. Therefore, it is necessary to focus on this issue further to address the

  20. Investigation of collisional excitation-transfer processes in a plasma by laser perturbation method

    Sakurai, Takeki

    1983-01-01

    The theoretical background and the experimental method of the laser perturbation method applied to the study of collisional excitation transfer process in plasma are explained. The atomic density at some specified level can be evaluated theoretically. By using the theoretical results and the experimentally obtained data, the total attenuation probability, the collisional transfer probability and natural emission probability were estimated. For the experiments, continuous wave laser (cw) and pulse laser are employed. It is possible by using pulse dye laser to observe the attenuation curve directly, and to bring in resonance to any atomic spectra. At the beginning, the experimental studies were made on He-Ne discharge. The pulse dye laser has been used for the excitation of alkali atoms. The first application of pulse laser to the study of plasma physics was the study on He. The cross section of disalignment has also been studied by the laser perturbation. The alignment of atoms, step and cascade transfer, the confinement of radiation and optogalvanic effect are discussed in this paper. (Kato, T.)

  1. Methods and system for controlled laser-driven explosive bonding

    Rubenchik, Alexander M.; Farmer, Joseph C.; Hackel, Lloyd; Rankin, Jon

    2015-11-19

    A technique for bonding two dissimilar materials includes positioning a second material over a first material at an oblique angle and applying a tamping layer over the second martial. A laser beam is directed at the second material that generates a plasma at the location of impact on the second material. The plasma generates pressure that accelerates a portion of the second material to a very high velocity and towards the first material. The second material impacts the first material causing bonding of the two materials.

  2. A laser optical method for detecting corn kernel defects

    Gunasekaran, S.; Paulsen, M. R.; Shove, G. C.

    1984-01-01

    An opto-electronic instrument was developed to examine individual corn kernels and detect various kernel defects according to reflectance differences. A low power helium-neon (He-Ne) laser (632.8 nm, red light) was used as the light source in the instrument. Reflectance from good and defective parts of corn kernel surfaces differed by approximately 40%. Broken, chipped, and starch-cracked kernels were detected with nearly 100% accuracy; while surface-split kernels were detected with about 80% accuracy. (author)

  3. NEW POSSIBILITIES OF ENVIRONMENTALY FRIENDLY CLEANING METHOD BY LASER TECHNOLOGY

    Lýdia Sobotová

    2016-12-01

    Full Text Available Still deteriorating environment, requirements for reducing of production waste, requirements for the protection of the working environment, the formation of new technologies and materials, as well as the economic conditions are forcing manufacturers to use the environmentally friendly technology. The contribution deals with new progressive possibilities of cleaning products, raw materials and with the establishment of a minimum production waste. The research focuses on the possibilities of laser cleaning of materials, under defined technological conditions. In the contribution is presented the results of realized experiments in Technical University of Kosice, together created in cooperation with Trumpf Slovakia, s.r.o

  4. Laser apparatus and method for microscopic and spectroscopic analysis and processing of biological cells

    Gourley, P.L.; Gourley, M.F.

    1997-03-04

    An apparatus and method are disclosed for microscopic and spectroscopic analysis and processing of biological cells. The apparatus comprises a laser having an analysis region within the laser cavity for containing one or more biological cells to be analyzed. The presence of a cell within the analysis region in superposition with an activated portion of a gain medium of the laser acts to encode information about the cell upon the laser beam, the cell information being recoverable by an analysis means that preferably includes an array photodetector such as a CCD camera and a spectrometer. The apparatus and method may be used to analyze biomedical cells including blood cells and the like, and may include processing means for manipulating, sorting, or eradicating cells after analysis. 20 figs.

  5. Ray tracing method for simulation of laser beam interaction with random packings of powders

    Kovalev, O. B.; Kovaleva, I. O.; Belyaev, V. V.

    2018-03-01

    Selective laser sintering is a technology of rapid manufacturing of a free form that is created as a solid object by selectively fusing successive layers of powder using a laser. The motivation of this study is due to the currently insufficient understanding of the processes and phenomena of selective laser melting of powders whose time scales differ by orders of magnitude. To construct random packings from mono- and polydispersed solid spheres, the algorithm of their generation based on the discrete element method is used. A numerical method of ray tracing is proposed that is used to simulate the interaction of laser radiation with a random bulk packing of spherical particles and to predict the optical properties of the granular layer, the extinction and absorption coefficients, depending on the optical properties of a powder material.

  6. Simulation of the output power of copper bromide lasers by the MARS method

    Iliev, I P; Voynikova, D S; Gocheva-Ilieva, S G

    2012-01-01

    The dependence of the output power of CuBr lasers (operating at wavelengths of 510.6 and 578.2 nm) on ten input physical parameters has been statistically analysed based on a large amount of experimental data accumulated for these lasers. Regression models have been built using the flexible nonparametric method of multivariate adaptive regression splines (MARS) to describe both linear and nonlinear local dependences. These models cover more than 97% initial data with an error comparable with the experimental error; they are applied to estimate and predict the output powers of both existing and future lasers. The advantage of the models constructed for estimating laser parameters over the standard parametric methods of multivariate factor and regression analysis is demonstrated.

  7. Measurements of natural uranium concentration in Caspian Sea and Persian Gulf water by laser fluorimetric method

    Garshasbi, H.; Karimi Diba, J.; Jahanbakhshian, M. H.; Asghari, S. K.; Heravi, G. H.

    2005-01-01

    Natural uranium exists in earth crust and seawater. The concentration of uranium might increase by human manipulation or geological changes. The aim of this study was to verify susceptibility of laser fluorimetry method to determine the uranium concentration in Caspian Sea and Persian Gulf water. Materials and Methods: Laser fluorimetric method was used to determine the uranium concentration in several samples prepared from Caspian Sea and Persian Gulf water. Biological and chemical substances were eliminated in samples for better evaluation of the method. Results: As the concentration of natural uranium in samples increases, the response of instrument (uranium analyzer) increases accordingly. The standard deviation also increased slightly and gradually. Conclusion: Results indicate that the laser fluorimetry method show a reliable and accurate response with uranium concentration up to 100 μg/L in samples after removal of biological and organic substances

  8. Two-micron (Thulium) Laser Prostatectomy: An Effective Method for BPH Treatment.

    Jiang, Qi; Xia, Shujie

    2014-01-01

    The two-micron (thulium) laser is the newest laser technique for treatment of bladder outlet obstruction resulting from benign prostatic hyperplasia (BPH). It takes less operative time than standard techniques, provides clear vision and lower blood loss as well as shorter catheterization times and hospitalization times. It has been identified to be a safe and efficient method for BPH treatment regardless of the prostate size.

  9. Method and apparatus for improving the quality and efficiency of ultrashort-pulse laser machining

    Stuart, Brent C.; Nguyen, Hoang T.; Perry, Michael D.

    2001-01-01

    A method and apparatus for improving the quality and efficiency of machining of materials with laser pulse durations shorter than 100 picoseconds by orienting and maintaining the polarization of the laser light such that the electric field vector is perpendicular relative to the edges of the material being processed. Its use is any machining operation requiring remote delivery and/or high precision with minimal collateral dames.

  10. Laser paper cleaning: the method of cleaning historical books

    Zekou, Evangelini; Tsilikas, Ioannis; Chatzitheodoridis, Elias; Serafetinides, Alexander A.

    2016-01-01

    Conservation of cultural heritage treasures is the most important issue for transferring knowledge to the public through the next generation of students, academics, and researchers. Although this century is authenticating e-books and information by means of electronic text, still historical manuscripts as content as well as objects are the main original recourses of keeping a record of this transformation. The current work focuses on cleaning paper samples by the application of pulsed light, which is interventional. Experiments carried out using paper samples that are artificially colonized with Ulocladium chartarum. Paper is treated by Nd:YAG laser light. The available wavelength is 1064 nm, at various fluences, repetition rates and number of pulses. Two types of paper are stained with fungi colonies, which grow on substrates of clean paper, as well as on paper with ink text. The first type of paper is Whatman No.1056, which is closer to pure cellulose. The second type of paper is a page of a cultural heritage book published in 1926. Cleaning is performed using laser irradiation, thus defining the damage threshold of each sample. The treatment on paper Watman showed a yellowing, especially on areas with high concentration of fungi. The second sample was more durable to the exposure, performing the best results at higher fluences. Eventually, the paper samples are characterized, with optical microscopy and SEM/EDX analyses, prior to and after cleaning.

  11. Laser speckle imaging: a novel method for detecting dental erosion.

    Nelson H Koshoji

    Full Text Available Erosion is a highly prevalent condition known as a non-carious lesion that causes progressive tooth wear due to chemical processes that do not involve the action of bacteria. Speckle images proved sensitive to even minimal mineral loss from the enamel. The aim of the present study was to investigate the use of laser speckle imaging analysis in the spatial domain to quantify shifts in the microstructure of the tooth surface in an erosion model. 32 fragments of the vestibular surface of bovine incisors were divided in for groups (10 min, 20 min. 30 min and 40 min of acid etching immersed in a cola-based beverage (pH approximately 2.5 twice a day during 7 days to create an artificial erosion. By analyzing the laser speckle contrast map (LASCA in the eroded region compared to the sound it was observed that the LASCA map shifts, proportionally to the acid each duration, by: 18%; 23%; 39% and 44% for the 10 min; 20 min; 30 min and 40 min groups, respectively. To the best of our knowledge, this is the first study to demonstrate the correlation between speckle patterns and erosion progression.

  12. Method of high precision interval measurement in pulse laser ranging system

    Wang, Zhen; Lv, Xin-yuan; Mao, Jin-jin; Liu, Wei; Yang, Dong

    2013-09-01

    Laser ranging is suitable for laser system, for it has the advantage of high measuring precision, fast measuring speed,no cooperative targets and strong resistance to electromagnetic interference,the measuremen of laser ranging is the key paremeters affecting the performance of the whole system.The precision of the pulsed laser ranging system was decided by the precision of the time interval measurement, the principle structure of laser ranging system was introduced, and a method of high precision time interval measurement in pulse laser ranging system was established in this paper.Based on the analysis of the factors which affected the precision of range measure,the pulse rising edges discriminator was adopted to produce timing mark for the start-stop time discrimination,and the TDC-GP2 high precision interval measurement system based on TMS320F2812 DSP was designed to improve the measurement precision.Experimental results indicate that the time interval measurement method in this paper can obtain higher range accuracy. Compared with the traditional time interval measurement system,the method simplifies the system design and reduce the influence of bad weather conditions,furthermore,it satisfies the requirements of low costs and miniaturization.

  13. A laser-abrasive method for the cutting of enamel and dentin.

    Altshuler, G B; Belikov, A V; Sinelnik, Y A

    2001-01-01

    This paper introduced a new method for the removal of hard dental tissue based upon the use of particles accelerated by laser irradiation, which the authors have called the laser-abrasive method. The particles used were sapphire as powder or an aqueous suspension. The effect of the products of enamel ablation was also investigated. The particles were accelerated using submillisecond pulses of Er:YAG and Nd:YAG lasers. A strobing CCD camera was used to measure the speed of the ejected particles. The additional contribution of these particles to the efficiency of laser ablation of enamel and dentin was also investigated. The results showed that the enamel particles produced by the beam-tissue interaction were also accelerated by this process of ablation and were effective in the removal of enamel and dentin. The use of an aqueous suspension of sapphire particles increased the efficiency of enamel removal threefold when compared with the use of an Er:YAG laser with water spray. The laser-abrasive method allowed for the removal of enamel and dentin at speeds approaching those of the high-speed turbine. Copyright 2001 Wiley-Liss, Inc.

  14. Spectral isotopic methods of determining nitrogen and carbon in plant specimens with laser volatization

    Lazeeva, G.S.

    1986-01-01

    Methods have been devised for the local determination of nitrogen and carbon isotope compositions in plant specimens, which provide separate and joint determination. Local laser evaporation has been combined with spectroscopic determination of the isotope compositions in the gas phase. A continuous-wave CO 2 laser is preferable for the local evaporation; the carbon isotope composition may be determined directly on the sum of the evaporation products, whereas nitrogen must first be separated as N 2 . Methods have also been developed for the local determination of total nitrogen and carbon in a sample with isotope dilution on the basis of laser evaporation. In order to eliminate systematic errors in determining total carbon in plant material, an evaporation method free from a rim has been devised. These methods have been used in determining isotope concentration profiles in plant specimens grown in experiments employing labeled nitrogen and carbon

  15. High-speed photographic methods for compression dynamics investigation of laser irradiated shell target

    Basov, N.G.; Kologrivov, A.A.; Krokhin, O.N.; Rupasov, A.A.; Shikanov, A.S.

    1979-01-01

    Three methods are described for a high-speed diagnostics of compression dynamics of shell targets being spherically laser-heated on the installation ''Kal'mar''. The first method is based on the direct investigation of the space-time evolution of the critical-density region for Nd-laser emission (N sub(e) asymptotically equals 10 21 I/cm 3 ) by means of the streak photography of plasma image in the second-harmonic light. The second method involves investigation of time evolution of the second-harmonic spectral distribution by means of a spectrograph coupled with a streak camera. The use of a special laser pulse with two time-distributed intensity maxima for the irradiation of shell targets, and the analysis of the obtained X-ray pin-hole pictures constitute the basis of the third method. (author)

  16. Parallel ion flow velocity measurement using laser induced fluorescence method in an electron cyclotron resonance plasma

    Yoshimura, Shinji; Okamoto, Atsushi; Terasaka, Kenichiro; Ogiwara, Kohei; Tanaka, Masayoshi Y.; Aramaki, Mitsutoshi

    2010-01-01

    Parallel ion flow velocity along a magnetic field has been measured using a laser induced fluorescence (LIF) method in an electron cyclotron resonance (ECR) argon plasma with a weakly-diverging magnetic field. To measure parallel flow velocity in a cylindrical plasma using the LIF method, the laser beam should be injected along device axis; however, the reflection of the incident beam causes interference between the LIF emission of the incident and reflected beams. Here we present a method of quasi-parallel laser injection at a small angle, which utilizes the reflected beam as well as the incident beam to obtain the parallel ion flow velocity. Using this method, we observed an increase in parallel ion flow velocity along the magnetic field. The acceleration mechanism is briefly discussed on the basis of the ion fluid model. (author)

  17. Comparison between laser terahertz emission microscope and conventional methods for analysis of polycrystalline silicon solar cell

    Hidetoshi Nakanishi

    2015-11-01

    Full Text Available A laser terahertz emission microscope (LTEM can be used for noncontact inspection to detect the waveforms of photoinduced terahertz emissions from material devices. In this study, we experimentally compared the performance of LTEM with conventional analysis methods, e.g., electroluminescence (EL, photoluminescence (PL, and laser beam induced current (LBIC, as an inspection method for solar cells. The results showed that LTEM was more sensitive to the characteristics of the depletion layer of the polycrystalline solar cell compared with EL, PL, and LBIC and that it could be used as a complementary tool to the conventional analysis methods for a solar cell.

  18. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    Yeung, E.S.; Chen, G.

    1990-05-01

    A method and means are disclosed for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived. 15 figs.

  19. Practical Method for engineering Erbium-doped fiber lasers from step-like pulse excitations

    Causado-Buelvas, J D; Gomez-Cardona, N D; Torres, P

    2011-01-01

    A simple method, known as 'easy points', has been applied to the characterization of Erbium-doped fibers, aiming for the engineering of fiber lasers. Using low- optical-power flattop pulse excitations it has been possible to determine both the attenuation coefficients and the intrinsic saturation powers of doped single-mode fibers at 980 and 1550 nm. Laser systems have been projected for which the optimal fiber length and output power have been determined as a function of the input power. Ring and linear laser cavities have been set up, and the characteristics of the output laser have been obtained and compared with the theoretical predictions based on the 'easy points' parameters.

  20. Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods

    Hora, H.; Aydin, M.

    1992-01-01

    The control of the very complex behavior of a plasma with laser interaction by smoothing with induced spatial incoherence or other methods was related to improving the lateral uniformity of the irradiation. While this is important, it is shown from numerical hydrodynamic studies that the very strong temporal pulsation (stuttering) will mostly be suppressed by these smoothing methods too

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

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

    2005-01-01

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

  2. PMT response drift of ATLAS Tile Laser II calibration system: an introduction of a new method

    Di Gregorio, Giulia

    2016-01-01

    In this article I describe the performance of the monitoring diodes of the Laser II system, a new system for run II used to calibrate the gain variation of PMTs in between two cesium scan. I also show a new method to measure the PMT drift response that it is compared to the method used up to now (Clermont-Ferrant) corrected with the Pisa method. The agreement between the two method is within 0.2%.

  3. Production of pulsed atomic oxygen beams via laser vaporization methods

    Brinza, D.E.; Coulter, D.R.; Liang, R.H.; Gupta, A.

    1987-01-01

    Energetic pulsed atomic oxygen beams were generated by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin films of indium-tin oxide (ITO). Mass and energy characterization of beams from the ozone/oxygen films were carried out by mass spectrometry. The peak flux, found to occur at 10 eV, is estimated from this data to be 3 x 10(20) m(-2) s(-1). Analysis of the time-of-flight data indicates a number of processes contribute to the formation of the atomic oxygen beam. The absence of metastable states such as the 2p(3) 3s(1) (5S) level of atomic oxygen blown off from ITO films is supported by the failure to observe emission at 777.3 nm from the 2p(3) 3p(1) (5P/sub J/) levels. Reactive scattering experiments with polymer film targets for atomic oxygen bombardment are planned using a universal crossed molecular beam apparatus

  4. Measured emittance dependence on injection method in laser plasma accelerators

    Barber, Samuel; van Tilborg, Jeroen; Schroeder, Carl; Lehe, Remi; Tsai, Hai-En; Swanson, Kelly; Steinke, Sven; Nakamura, Kei; Geddes, Cameron; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2017-10-01

    The success of many laser plasma accelerator (LPA) based applications relies on the ability to produce electron beams with excellent 6D brightness, where brightness is defined as the ratio of charge to the product of the three normalized emittances. As such, parametric studies of the emittance of LPA generated electron beams are essential. Profiting from a stable and tunable LPA setup, combined with a carefully designed single-shot transverse emittance diagnostic, we present a direct comparison of charge dependent emittance measurements of electron beams generated by two different injection mechanisms: ionization injection and shock induced density down-ramp injection. Notably, the measurements reveal that ionization injection results in significantly higher emittance. With the down-ramp injection configuration, emittances less than 1 micron at spectral charge densities up to 2 pC/MeV were measured. This work was supported by the U.S. DOE under Contract No. DE-AC02-05CH11231, by the NSF under Grant No. PHY-1415596, by the U.S. DOE NNSA, DNN R&D (NA22), and by the Gordon and Betty Moore Foundation under Grant ID GBMF4898.

  5. Applications of laser-photoacoustic gas analysis method

    Hernberg, R.; Stenberg, J. [Tampere Univ. of Technology (Finland). Dept. of Physics

    1996-12-01

    The dynamic behavior of a circulating fluidized bed boiler (CFB) was studied using two high speed gas analysis systems during combustion of coal, peat and wood chips. Time resolved concentrations of some pollutants (SO{sub 2}, NO, NH{sub 3} and H{sub 2}S) were measured using laser induced photoacoustic spectroscopy (LIPS). A zirkonia cell based probe (lambda-probe) was used in synchronization with the LIPS-probe to measure fluctuations between reducing and oxidizing conditions. The two probes were positioned in the same measurement volume on the center-line of the combustion chamber of the CFB. The purpose of the measurements was to investigate the behavior of the LIPS in a combustion chamber containing large amounts of other unburnt hydrocarbons. The correlations between oxidizing and reducing conditions and concentrations at three locations in the combustion chamber are presented. The best correlations were found in the upper part of the CFB combustion chamber. In some cases the correlations between reducing conditions and the LIPS signal were caused by hydrocarbons. Comparison of the average values obtained by the LIPS-system for NO and SO{sub 2} with the result from a sampling probe system connected to on-line analysers was also carried out. (author)

  6. Method of measuring directed electron velocities in flowing plasma using the incoherent regions of laser scattering

    Jacoby, B.A.; York, T.M.

    1979-02-01

    With the presumption that a shifted Maxwellian velocity distribution adequately describes the electrons in a flowing plasma, the details of a method to measure their directed velocity are described. The system consists of a ruby laser source and two detectors set 180 0 from each other and both set at 90 0 with respect to the incident laser beam. The lowest velocity that can be determined by this method depends on the electron thermal velocity. The application of this diagnostic to the measurement of flow velocities in plasma being lost from the ends of theta-pinch devices is described

  7. Comparison on different repetition rate locking methods in Er-doped fiber laser

    Yang, Kangwen; Zhao, Peng; Luo, Jiang; Huang, Kun; Hao, Qiang; Zeng, Heping

    2018-05-01

    We demonstrate a systematic comparative research on the all-optical, mechanical and opto-mechanical repetition rate control methods in an Er-doped fiber laser. A piece of Yb-doped fiber, a piezoelectric transducer and an electronic polarization controller are simultaneously added in the laser cavity as different cavity length modulators. By measuring the cavity length tuning ranges, the output power fluctuations, the temporal and frequency repetition rate stability, we show that all-optical method introduces the minimal disturbances under current experimental condition.

  8. Application of laser cladding method to small-diameter stainless steel pipes in actual nuclear plant

    Atago, Y.; Yamadera, M.; Tsuji, H.; Shiraiwa, T.; Kanno, M.

    1995-01-01

    Recently, to prevent stress corrosion cracking (SCC) the material of stainless steel (Type 304), a laser cladding method which produces a highly corrosion-resisting coating (cladding) to be formed on the surface of the material was developed. This is applicable to a long distance and narrow space, because of the good accessibility of the YAG (Yttrium-Aluminum Garnet) laser beam that can be transmitted through an optical fiber. In this method, a paste mixed metallic powder and heating resistive organic solvent is firstly placed on the inner surface of a small pipe and then a YAG laser beam transmitted through an optical fiber is irradiated to the paste, which will be melted and formed a clad subsequently, which is excellent in corrosion resistance. Finally, it can be achieved further resistance against the SCC due to the clad layer formed thus on the surface of the material. Recently, this Laser Cladding method was practically and successfully applied to the actual BWR Nuclear Power Plant in Japan. This report introduces the laser cladding technique, the equipments developed for practical application in the field

  9. Fabrication of metallic surfaces with long-term superhydrophilic property using one-stop laser method

    Guan, Y.C.; Luo, F.F.; Lim, G.C.; Hong, M.H.; Zheng, H.Y.; Qi, Bojin

    2015-01-01

    Highlights: • One-stop laser method is presented to fabricate superhydrophilic surface on metals. • Wettability study shows the longest superhydrophilic duration as more than 1 month. • Water-soluble compounds, polar functional groups and dual-scale structures were formed. • Surface roughness shows an amplification effect of the wetting behavior. - Abstract: A simple method for fabricating stable superhydrophilic surface at metallic substrates is reported. This technique comprises irradiating the surface with multiple laser pulses. Surface wettability can be taylored through controlling laser parameters and processing conditions. The substrates were selected as aluminum alloy and stainless steel. Physical morphology and chemical composition of laser-textured surfaces were characterized by SEM, XPS, and 3D profiler measurements. Results showed that the longest wettability duration was achieved as more than 1 month for stainless steel and more than 200 h for Al alloy, respectively. The possible mechanism of hydrophilic behavior of laser-textured surfaces was discussed. The effect of surface topography on superhydrophilicity property was also evaluated. This study presents a promising method in fabricating long-term superhydrophilic surfaces, which is useful for improving adhesion or achieving water-assisted flow in industrial applications as well as developing cell-based technologies in biomedical applications

  10. Application of laser ultrasonic method for on-line monitoring of friction stir spot welding process.

    Zhang, Kuanshuang; Zhou, Zhenggan; Zhou, Jianghua

    2015-09-01

    Application of a laser ultrasonic method is developed for on-line monitoring of the friction stir spot welding (FSSW) process. Based on the technology of FSSW, laser-generated ultrasonic waves in a good weld and nonweld area are simulated by a finite element method. The reflected and transmitted waves are analyzed to disclose the properties of the welded interface. The noncontact-laser ultrasonic-inspection system was established to verify the numerical results. The reflected waves in the good-weld and nonweld area can be distinguished by time-of-flight. The transmitted waves evidently attenuate in the nonweld area in contrast to signal amplitude in the good weld area because of interfacial impedance difference. Laser ultrasonic C-scan images can sufficiently evaluate the intrinsic character of the weld area in comparison with traditional water-immersion ultrasonic testing results. The research results confirm that laser ultrasonics would be an effective method to realize the characterization of FSSW defects.

  11. Diamond coating deposition by synergy of thermal and laser methods-A problem revisited

    Ristic, Gordana S.; Trtica, Milan S.; Bogdanov, Zarko D.; Romcevic, Nebojsa Z.; Miljanic, Scepan S.

    2007-01-01

    Diamond coatings were deposited by synergy of the hot filament CVD method and the pulse TEA CO 2 laser, in spectroactive and spectroinactive diamond precursor atmospheres. Resulting diamond coatings are interpreted relying on evidence of scanning electron microscopy as well as microRaman spectroscopy. Thermal synergy component (hot filament) possesses an activating agent for diamond deposition, and contributes significantly to quality and extent of diamond deposition. Laser synergy component comprises a solid surface modification as well as the spectroactive gaseous atmosphere modification. Surface modification consists in changes of the diamond coating being deposited and, at the same time, in changes of the substrate surface structure. Laser modification of the spectroactive diamond precursor atmosphere means specific consumption of the precursor, which enables to skip the deposition on a defined substrate location. The resulting process of diamond coating elimination from certain, desired locations using the CO 2 laser might contribute to tailoring diamond coatings for particular applications. Additionally, the substrate laser modification could be optimized by choice of a proper spectroactive precursor concentration, or by a laser radiation multiple pass through an absorbing medium

  12. Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2011-01-01

    This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 μm and 150 μm. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 μm. The maximum hardness achieved was between 728 and 905 HV0.1. These findings are significant to modern development of hard coatings for wear resistant applications.

  13. Analysis of a wavelength selectable cascaded DFB laser based on the transfer matrix method

    Xie Hongyun; Chen Liang; Shen Pei; Sun Botao; Wang Renqing; Xiao Ying; You Yunxia; Zhang Wanrong

    2010-01-01

    A novel cascaded DFB laser, which consists of two serial gratings to provide selectable wavelengths, is presented and analyzed by the transfer matrix method. In this method, efficient facet reflectivity is derived from the transfer matrix built for each serial section and is then used to simulate the performance of the novel cascaded DFB laser through self-consistently solving the gain equation, the coupled wave equation and the current continuity equations. The simulations prove the feasibility of this kind of wavelength selectable laser and a corresponding designed device with two selectable wavelengths of 1.51 μm and 1.53 μm is realized by experiments on InP-based multiple quantum well structure. (semiconductor devices)

  14. Residence space/graphic space: engravings in the open air in the municipality of La Hinojosa (Cuenca

    Bueno Ramírez, Primitiva

    1998-06-01

    Full Text Available The work that now we present is based on the analysis of graphic designs, their location and their relationship to the environment, in the municipality of La Hinojosa Cuenca, a place where we have well documented occupations of the Copper and Bronze Ages. Our aim is to understand these engravings as part of the expressions of peninsular Schematic Art, in this case associated with an occupational context, and to provide elements for the comprehension of its message in a broader context that includes occupational contexts for other open aire engravings in the Iberian Peninsula.

    El trabajo que ahora presentamos se basa en el análisis de las grafías, su ubicación en el soporte y su relación con el entorno, en una zona concreta, el término de La Hinojosa, en Cuenca, lugar en el que tenemos bien documentadas ocupaciones calcolíticas y de la Edad del Bronce. Nuestra propuesta es la de comprender dichos grabados como una parte de las expresiones del Arte Esquemático peninsular, en este caso asociadas a un contexto habitacional y, a partir de ahí, aportar elementos para la comprensión de su "mensaje" desde una perspectiva más amplia que incluye otros contextos habitacionales para conjuntos de grabados al aire libre en la Península Ibérica.

  15. Creating compact and microscale features in paper-based devices by laser cutting.

    Mahmud, Md Almostasim; Blondeel, Eric J M; Kaddoura, Moufeed; MacDonald, Brendan D

    2016-11-14

    In this work we describe a fabrication method to create compact and microscale features in paper-based microfluidic devices using a CO 2 laser cutting/engraving machine. Using this method we are able to produce the smallest features with the narrowest barriers yet reported for paper-based microfluidic devices. The method uses foil backed paper as the base material and yields inexpensive paper-based devices capable of using small fluid sample volumes and thus small reagent volumes, which is also suitable for mass production. The laser parameters (power and laser head speed) were adjusted to minimize the width of hydrophobic barriers and we were able to create barriers with a width of 39 ± 15 μm that were capable of preventing cross-barrier bleeding. We generated channels with a width of 128 ± 30 μm, which we found to be the physical limit for small features in the chromatography paper we used. We demonstrate how miniaturizing of paper-based microfluidic devices enables eight tests on a single bioassay device using only 2 μL of sample fluid volume.

  16. A novel calibration method for non-orthogonal shaft laser theodolite measurement system

    Wu, Bin, E-mail: wubin@tju.edu.cn, E-mail: xueting@tju.edu.cn; Yang, Fengting; Ding, Wen [State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072 (China); Xue, Ting, E-mail: wubin@tju.edu.cn, E-mail: xueting@tju.edu.cn [College of Electrical Engineering and Automation, Tianjin Key Laboratory of Process Measurement and Control, Tianjin University, Tianjin 300072 (China)

    2016-03-15

    Non-orthogonal shaft laser theodolite (N-theodolite) is a new kind of large-scale metrological instrument made up by two rotary tables and one collimated laser. There are three axes for an N-theodolite. According to naming conventions in traditional theodolite, rotary axes of two rotary tables are called as horizontal axis and vertical axis, respectively, and the collimated laser beam is named as sight axis. And the difference between N-theodolite and traditional theodolite is obvious, since the former one with no orthogonal and intersecting accuracy requirements. So the calibration method for traditional theodolite is no longer suitable for N-theodolite, while the calibration method applied currently is really complicated. Thus this paper introduces a novel calibration method for non-orthogonal shaft laser theodolite measurement system to simplify the procedure and to improve the calibration accuracy. A simple two-step process, calibration for intrinsic parameters and for extrinsic parameters, is proposed by the novel method. And experiments have shown its efficiency and accuracy.

  17. High power CO2 laser development with AOM integration for ultra high-speed pulses

    Bohrer, Markus; Vaupel, Matthias; Nirnberger, Robert; Weinberger, Bernhard; Jamalieh, Murad

    2017-01-01

    There is a 500 billion USD world market for packaging expected to grow to a trillion in 2030. Austria plays an important role world wide for high speed laser engraving applications — especially when it comes to high end solutions. Such high end solutions are fundamental for the production of print forms for the packaging and decorating industry (e. g. cans). They are additionally used for security applications (e. g. for printing banknotes), for the textile printing industry and for creating embossing forms (e. g. for the production of dashboards in the automotive industry). High speed, high precision laser engraving needs laser resonators with very stable laser beams (400 - 800W) especially in combination with AOMs. Based upon a unique carbon fiber structure - stable within the sub-micrometer range - a new resonator has been developed, accompanied by most recent thermo-mechanical FEM calculations. The resulting beam is evaluated on an automated optical bench using hexapods, allowing to optimize the complete beam path with collimators and AOM. The major steps related to laser engraving of dry offset printing plates during the full workflow from the artists design to the printed result on an aluminum can is presented in this paper as well as laser characteristics, AOM integration and correlative CLSM and SEM investigation of the results.

  18. Apparatus and method for increasing the bandwidth of a laser beam

    Wilcox, Russell B.

    1992-01-01

    A method and apparatus using sinusoidal cross-phase modulation, provides a laser pulse having a very broad bandwidth while substantially retaining the input laser's temporal shape. The modulator may be used in a master oscillator system for a laser having a master oscillator-power amplifier (MOPA) configration. The modulator utilizes a first laser providing an output wavelength .lambda. and a second laser providing an output wavelength shifted by a small amount to .lambda.+.DELTA..lambda.. Each beam has a single, linear polarization. Each beam is coupled into a length of polarization-preserving optical fiber. The first laser beam is coupled into the optical fiber with the beam's polarization aligned with the fiber's main axis, and the second beam is coupled into the fiber with its polarization rotated from the main axis by a predetermined angle. Within the fiber, the main axis' polarization defines an interference beam and the orthogonal axis' polarization defines a signal beam. In the interference beam, the first laser beam and the parallel polarized vector component of the other beam interfere to create areas of high and low intensity, which modulates the signal beam by cross phase modulation. Upon exit from the optical fiber, the beams are coupled out and the modulated signal beam is separated out by a polarization selector. The signal beam can be applied to coherence reducing systems to provide an output that is temporally and spatially incoherent. The U.S. Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the U.S. Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.

  19. A High Precision Laser-Based Autofocus Method Using Biased Image Plane for Microscopy

    Chao-Chen Gu

    2018-01-01

    Full Text Available This study designs and accomplishes a high precision and robust laser-based autofocusing system, in which a biased image plane is applied. In accordance to the designed optics, a cluster-based circle fitting algorithm is proposed to calculate the radius of the detecting spot from the reflected laser beam as an essential factor to obtain the defocus value. The experiment conduct on the experiment device achieved novel performance of high precision and robustness. Furthermore, the low demand of assembly accuracy makes the proposed method a low-cost and realizable solution for autofocusing technique.

  20. Systems and methods for laser assisted sample transfer to solution for chemical analysis

    Van Berkel, Gary J; Kertesz, Vilmos; Ovchinnikova, Olga S

    2013-08-27

    Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

  1. Laser Based In Situ Techniques: Novel Methods for Generating Extreme Conditions in TEM Samples

    Taheri, M; Lagrange, T; Reed, B; Armstrong, M; Campbell, G; DeHope, W; Kim, J; King, W; Masiel, D; Browning, N

    2008-02-25

    The Dynamic Transmission Electron Microscope (DTEM) is introduced as a novel tool for in situ processing of materials. Examples of various types of dynamic studies outline the advantages and differences of laser-based heating in the DTEM in comparison to conventional (resistive) heating in situ TEM methods. We demonstrate various unique capabilities of the drive laser, namely, in situ processing of nanoscale materials, rapid and high temperature phase transformations, and controlled thermal activation of materials. These experiments would otherwise be impossible without the use of the DTEM drive laser. Thus, the potential of the DTEM to as a new technique to process and characterize the growth of a myriad of micro and nanostructures is demonstrated.

  2. Free Electron Laser Induced Forward Transfer Method of Biomaterial for Marking

    Suzuki, Kaoru

    Biomaterial, such as chitosan, poly lactic acid, etc., containing fluorescence agent was deposited onto biology hard tissue, such as teeth, fingernail of dog or cat, or sapphire substrate by free electron laser induced forward transfer method for direct write marking. Spin-coated biomaterial with fluorescence agent of rhodamin-6G or zinc phthalochyamine target on sapphire plate was ablated by free electron laser (resonance absorption wavelength of biomaterial : 3380 nm). The influence of the spin-coating film-forming temperature on hardness and adhesion strength of biomaterial is particularly studied. Effect of resonance excitation of biomaterial target by turning free electron laser was discussed to damage of biomaterial, rhodamin-6G or zinc phtarochyamine for direct write marking

  3. Study of laser radar system using the differential absorption method for detection of air pollutants

    Inomata, H; Igarashi, T

    1975-11-01

    A laser radar system using the differential absorption method for remote measurement of atmospheric NO/sub 2/ and SO/sub 2/ is studied. A simultaneous two-wavelength dye laser for the transmitter and a simultaneous two-wavelength signal processer for the receiver are developed. In using this technique, one laser shot allows the determination of NO/sub 2/ concentrations with an uncertainty equivalent to 44 ppM times the range interval (in meters). It seems that the technique is most promising for a range-resolved measurement of ambient molecular pollutants, since it has the advantage of canceling the effect of atmospheric variation in a measurement when atmospheric aerosols are used as a distributed reflector.

  4. Smooth polishing of femtosecond laser induced craters on cemented carbide by ultrasonic vibration method

    Wang, H. P.; Guan, Y. C.; Zheng, H. Y.

    2017-12-01

    Rough surface features induced by laser irradiation have been a challenging for the fabrication of micro/nano scale features. In this work, we propose hybrid ultrasonic vibration polishing method to improve surface quality of microcraters produced by femtosecond laser irradiation on cemented carbide. The laser caused rough surfaces are significantly smoothened after ultrasonic vibration polishing due to the strong collision effect of diamond particles on the surfaces. 3D morphology, SEM and AFM analysis has been conducted to characterize surface morphology and topography. Results indicate that the minimal surface roughness of Ra 7.60 nm has been achieved on the polished surfaces. The fabrication of microcraters with smooth surfaces is applicable to molding process for mass production of micro-optical components.

  5. Apparatus and method for the spectrochemical analysis of liquids using the laser spark

    Cremers, David A.; Radziemski, Leon J.; Loree, Thomas R.

    1990-01-01

    A method and apparatus for the qualitative and quantitative spectroscopic investigation of elements present in a liquid sample using the laser spark. A series of temporally closely spaced spark pairs is induced in the liquid sample utilizing pulsed electromagnetic radiation from a pair of lasers. The light pulses are not significantly absorbed by the sample so that the sparks occur inside of the liquid. The emitted light from the breakdown events is spectrally and temporally resolved, and the time period between the two laser pulses in each spark pair is adjusted to maximize the signal-to-noise ratio of the emitted signals. In comparison with the single pulse technique, a substantial reduction in the limits of detectability for many elements has been demonstrated. Narrowing of spectral features results in improved discrimination against interfering species.

  6. Femtosecond laser surface texturing of titanium as a method to reduce the adhesion of Staphylococcus aureus and biofilm formation

    Cunha, Alexandre [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Elie, Anne-Marie [Bordeaux University, CBMN UMR 5248, CNRS, Bordeaux Science Agro, 1 Rue du G. de Gaulle, 33170 Gradignan (France); Plawinski, Laurent [Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Serro, Ana Paula [Instituto Superior Técnico, Universidade de Lisboa, CQE-Centro de Química Estrutural, Av. Rovisco Pais 1, 1049-001 Lisbon (Portugal); Botelho do Rego, Ana Maria [Instituto Superior Técnico, Universidade de Lisboa, CQFM-Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology - IN, Av. Rovisco Pais 1, 1049-001 Lisbon (Portugal); Almeida, Amélia [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Urdaci, Maria C. [Bordeaux University, CBMN UMR 5248, CNRS, Bordeaux Science Agro, 1 Rue du G. de Gaulle, 33170 Gradignan (France); Durrieu, Marie-Christine [Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Vilar, Rui, E-mail: rui.vilar@tecnico.ulisboa.pt [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

    2016-01-01

    Graphical abstract: - Highlights: • The short-term adhesion of Staphylococcus aureus onto femtosecond laser textured surfaces of titanium was investigated. • The laser textured surfaces consist of laser-induced periodic surface structures (LIPSS) and nanopillars. • The laser treatment enhances the hydrophilicity and the surface free energy of the material. • The laser treatment reduces significantly the adhesion of S. aureus and biofilm formation. • Femtosecond laser surface texturing of titanium is a simple and promising method for endowing dental and orthopedic implants with antibacterial properties. - Abstract: The aim of the present work was to investigate the possibility of using femtosecond laser surface texturing as a method to reduce the colonization of Grade 2 Titanium alloy surfaces by Staphylococcus aureus and the subsequent formation of biofilm. The laser treatments were carried out with a Yb:KYW chirped-pulse-regenerative amplification laser system with a central wavelength of 1030 nm and a pulse duration of 500 fs. Two types of surface textures, consisting of laser-induced periodic surface structures (LIPSS) and nanopillars, were produced. The topography, chemical composition and phase constitution of these surfaces were investigated by atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction. Surface wettability was assessed by the sessile drop method using water and diiodomethane as testing liquids. The response of S. aureus put into contact with the laser treated surfaces in controlled conditions was investigated by epifluorescence microscopy and scanning electron microscopy 48 h after cell seeding. The results achieved show that the laser treatment reduces significantly the bacterial adhesion to the surface as well as biofilm formation as compared to a reference polished surfaces and suggest that femtosecond laser texturing is a simple and promising method

  7. DEVICE FOR MEASURING OF THERMAL LENS PARAMETERS IN LASER ACTIVE ELEMENTS WITH A PROBE BEAM METHOD

    A. N. Zakharova

    2015-01-01

    Full Text Available We have developed a device for measuring of parameters of thermal lens (TL in laser active elements under longitudinal diode pumping. The measurements are based on the probe beam method. This device allows one to determine sign and optical power of the lens in the principal meridional planes, its sensitivity factor with respect to the absorbed pump power and astigmatism degree, fractional heat loading which make it possible to estimate integral impact of the photoelastic effect to the formation of TL in the laser element. The measurements are performed in a linearly polarized light at the wavelength of 532 nm. Pumping of the laser element is performed at 960 nm that makes it possible to study laser materials doped with Yb3+ and (Er3+, Yb3+ ions. The precision of measurements: for sensitivity factor of TL – 0,1 m-1/W, for astigmatism degree – 0,2 m-1/W, for fractional heat loading – 5 %, for the impact of the photoelastic effect – 0,5 × 10-6 K-1. This device is used for characterization of thermal lens in the laser active element from an yttrium vanadate crystal, Er3+,Yb3+:YVO .

  8. GPC Light Shaper for energy efficient laser materials processing

    Bañas, Andrew Rafael; Palima, Darwin; Villangca, Mark Jayson

    The biggest use of lasers is in materials processing. In manufacturing, lasers are used for cutting, drilling, marking and other machining processes. Similarly, lasers are important in microfabrication processes such as photolithography, direct laser writing, or ablation. Lasers are advantageous...... with steep, well defined edges that would further increase laser cutting precision or allow “single shot” laser engraving of arbitrary 2D profiles, as opposed to point scanning [3,4]. Instead of lossy approaches, GPC beam shaping is achieved with simplified, binary phase-only optics [5] that redistributes...... because they do not wear out, have no physical contact with the processed material, avoid heating or warping effects, and are generally more precise. Since lasers are easier to adapt to different optimized shapes, they can be even more precise and energy efficient for materials processing. The cost...

  9. Research on horizontal displacement monitoring method of deep foundation pit based on laser projecting sensing technology

    Liu, Peng; Xie, Shulin; Zhang, Lixiao; Zhou, Guangyi; Zhao, Xuefeng

    2018-03-01

    A certain level of horizontal displacement will occur during excavation or subsequent construction of deep foundation pit. If the support is improper and the horizontal displacement of the foundation pit is too large, it will cause collapse and even affect the buildings around the foundation pit, which will endanger people's life and property. Therefore, the horizontal displacement monitoring of deep foundation pit becomes more and more important. At present, the electronic total station is often used to monitor the horizontal displacement of the foundation pit, but this monitoring method is expensive, prone to accidental errors, and can not be used for real-time monitoring. Therefore, a method of monitoring the horizontal displacement of deep foundation pit by using laser projection sensing technique is proposed in this paper. The horizontal displacement of the foundation pit is replaced by the displacement of the laser spot emitted by the laser, and the horizontal displacement of the foundation pit can be obtained by identifying the displacement of the laser spot projected on the screen. A series of experiments show that the accuracy of this monitoring method meets the engineering requirements and greatly reduces the cost, which provides a new technology for the displacement monitoring of deep foundation pit.

  10. High-precision pose measurement method in wind tunnels based on laser-aided vision technology

    Liu Wei

    2015-08-01

    Full Text Available The measurement of position and attitude parameters for the isolated target from a high-speed aircraft is a great challenge in the field of wind tunnel simulation technology. In this paper, firstly, an image acquisition method for small high-speed targets with multi-dimensional movement in wind tunnel environment is proposed based on laser-aided vision technology. Combining with the trajectory simulation of the isolated model, the reasonably distributed laser stripes and self-luminous markers are utilized to capture clear images of the object. Then, after image processing, feature extraction, stereo correspondence and reconstruction, three-dimensional information of laser stripes and self-luminous markers are calculated. Besides, a pose solution method based on projected laser stripes and self-luminous markers is proposed. Finally, simulation experiments on measuring the position and attitude of high-speed rolling targets are conducted, as well as accuracy verification experiments. Experimental results indicate that the proposed method is feasible and efficient for measuring the pose parameters of rolling targets in wind tunnels.

  11. Research on a high-precision calibration method for tunable lasers

    Xiang, Na; Li, Zhengying; Gui, Xin; Wang, Fan; Hou, Yarong; Wang, Honghai

    2018-03-01

    Tunable lasers are widely used in the field of optical fiber sensing, but nonlinear tuning exists even for zero external disturbance and limits the accuracy of the demodulation. In this paper, a high-precision calibration method for tunable lasers is proposed. A comb filter is introduced and the real-time output wavelength and scanning rate of the laser are calibrated by linear fitting several time-frequency reference points obtained from it, while the beat signal generated by the auxiliary interferometer is interpolated and frequency multiplied to find more accurate zero crossing points, with these points being used as wavelength counters to resample the comb signal to correct the nonlinear effect, which ensures that the time-frequency reference points of the comb filter are linear. A stability experiment and a strain sensing experiment verify the calibration precision of this method. The experimental result shows that the stability and wavelength resolution of the FBG demodulation can reach 0.088 pm and 0.030 pm, respectively, using a tunable laser calibrated by the proposed method. We have also compared the demodulation accuracy in the presence or absence of the comb filter, with the result showing that the introduction of the comb filter results to a 15-fold wavelength resolution enhancement.

  12. [Efficiency of combined methods of hemorroid treatment using hal-rar and laser destruction].

    Rodoman, G V; Kornev, L V; Shalaeva, T I; Malushenko, R N

    2017-01-01

    To develop the combined method of treatment of hemorrhoids with arterial ligation under Doppler control and laser destruction of internal and external hemorrhoids. The study included 100 patients with chronic hemorrhoids stage II and III. Combined method of HAL-laser was used in study group, HAL RAR-technique in control group 1 and closed hemorrhoidectomy with linear stapler in control group 2. Сomparative evaluation of results in both groups was performed. Combined method overcomes the drawbacks of traditional surgical treatment and limitations in external components elimination which are inherent for HAL-RAR. Moreover, it has a higher efficiency in treating of hemorrhoids stage II-III compared with HAL-RAR and is equally safe and well tolerable for patients. This method does not increase the risk of recurrence, reduces incidence of complications and time of disability.

  13. CO2 Laser-Based Rapid Prototyping of Micropumps

    Zachary Strike

    2018-05-01

    Full Text Available The fabrication of microdevices for fluidic control often requires the use of flexible diaphragms in a way that requires cleanroom equipment and compromises performance. We use a CO 2 laser to perform the standard ablative techniques of cutting and engraving materials, but we also apply a method that we call laser placement. This allows us to fabricate precisely-positioned and precisely-sized, isolated diaphragms. This in turn enables the rapid prototyping of integrated multilayer microfluidic devices to form complex structures without the need for manual positioning or cleanroom equipment. The fabrication process is also remarkably rapid and capable of being scaled to manufacturing levels of production. We explore the use of these devices to construct a compact system of peristaltic pumps that can form water in oil droplets without the use of the non-pulsatile pumping systems typically required. Many devices can be fabricated at a time on a sheet by sheet basis with a fabrication process that, to our knowledge, is the fastest reported to date for devices of this type (requiring only 3 h. Moreover, this system is unusually compact and self-contained.

  14. The element analysis of high purity beryllium by method of laser mass-spectrometry

    Virich, V.D.; Kisel', O.V.; Kovtun, K.V.; Pugachev, N.S.; Yakobson, L.A.

    2003-01-01

    The operation is devoted to examination of a possibility of the analysis of element composition pure and high purity model of a beryllium is model by a method of laser mass spectrometry. The advantages of a method in a part of finding of a small amount of admixtures in comparison with other modes of the analysis are exhibited. The possibility of quantitative definition of a content in beryllium samples of gas-making admixtures-C,N,O surveyed

  15. Laser methods for detecting explosive residues on surfaces of distant objects

    Skvortsov, L A [Institute of Cryptography, Communications and Informatics, Moscow (Russian Federation)

    2012-01-31

    The basic methods of laser spectroscopy that are used for standoff detection and identification of explosive traces in the form of particles on the surfaces of objects tested under real or close-toreal conditions are briefly considered. The advantages and drawbacks of all methods are discussed and their characteristics are compared. Particular attention has been given to the prospects of development and practical implementation of the technologies discussed and justification of their most preferred applications. (review)

  16. Computational method for an axisymmetric laser beam scattered by a body of revolution

    Combis, P.; Robiche, J.

    2005-01-01

    An original hybrid computational method to solve the 2-D problem of the scattering of an axisymmetric laser beam by an arbitrary-shaped inhomogeneous body of revolution is presented. This method relies on a domain decomposition of the scattering zone into concentric spherical radially homogeneous sub-domains and on an expansion of the angular dependence of the fields on the Legendre polynomials. Numerical results for the fields obtained for various scatterers geometries are presented and analyzed. (authors)

  17. Histological staining methods preparatory to laser capture microdissection significantly affect the integrity of the cellular RNA

    Wang, Hongyang; Owens, James D; Shih, Joanna H; Li, Ming-Chung; Bonner, Robert F; Mushinski, J Frederic

    2006-01-01

    Abstract Background Gene expression profiling by microarray analysis of cells enriched by laser capture microdissection (LCM) faces several technical challenges. Frozen sections yield higher quality RNA than paraffin-imbedded sections, but even with frozen sections, the staining methods used for histological identification of cells of interest could still damage the mRNA in the cells. To study the contribution of staining methods to degradation of results from gene expression profiling of LCM...

  18. Determination of laser cutting process conditions using the preference selection index method

    Madić, Miloš; Antucheviciene, Jurgita; Radovanović, Miroslav; Petković, Dušan

    2017-03-01

    Determination of adequate parameter settings for improvement of multiple quality and productivity characteristics at the same time is of great practical importance in laser cutting. This paper discusses the application of the preference selection index (PSI) method for discrete optimization of the CO2 laser cutting of stainless steel. The main motivation for application of the PSI method is that it represents an almost unexplored multi-criteria decision making (MCDM) method, and moreover, this method does not require assessment of the considered criteria relative significances. After reviewing and comparing the existing approaches for determination of laser cutting parameter settings, the application of the PSI method was explained in detail. Experiment realization was conducted by using Taguchi's L27 orthogonal array. Roughness of the cut surface, heat affected zone (HAZ), kerf width and material removal rate (MRR) were considered as optimization criteria. The proposed methodology is found to be very useful in real manufacturing environment since it involves simple calculations which are easy to understand and implement. However, while applying the PSI method it was observed that it can not be useful in situations where there exist a large number of alternatives which have attribute values (performances) very close to those which are preferred.

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

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

    2012-01-01

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

  20. Modified Laser Flash Method for Thermal Properties Measurements and the Influence of Heat Convection

    Lin, Bochuan; Zhu, Shen; Ban, Heng; Li, Chao; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2003-01-01

    The study examined the effect of natural convection in applying the modified laser flash method to measure thermal properties of semiconductor melts. Common laser flash method uses a laser pulse to heat one side of a thin circular sample and measures the temperature response of the other side. Thermal diffusivity can be calculations based on a heat conduction analysis. For semiconductor melt, the sample is contained in a specially designed quartz cell with optical windows on both sides. When laser heats the vertical melt surface, the resulting natural convection can introduce errors in calculation based on heat conduction model alone. The effect of natural convection was studied by CFD simulations with experimental verification by temperature measurement. The CFD results indicated that natural convection would decrease the time needed for the rear side to reach its peak temperature, and also decrease the peak temperature slightly in our experimental configuration. Using the experimental data, the calculation using only heat conduction model resulted in a thermal diffusivity value is about 7.7% lower than that from the model with natural convection. Specific heat capacity was about the same, and the difference is within 1.6%, regardless of heat transfer models.

  1. Laser interferometric method for determining the carrier diffusion length in semiconductors

    Manukhov, V. V. [Saint Petersburg State University (Russian Federation); Fedortsov, A. B.; Ivanov, A. S., E-mail: ivaleks58@gmail.com [Saint Petersburg Mining University (Russian Federation)

    2015-09-15

    A new laser interferometric method for measuring the carrier diffusion length in semiconductors is proposed. The method is based on the interference–absorption interaction of two laser radiations in a semiconductor. Injected radiation generates additional carriers in a semiconductor, which causes a change in the material’s optical constants and modulation of the probing radiation passed through the sample. When changing the distance between carrier generation and probing points, a decrease in the carrier concentration, which depends on the diffusion length, is recorded. The diffusion length is determined by comparing the experimental and theoretical dependences of the probe signal on the divergence of the injector and probe beams. The method is successfully tested on semiconductor samples with different thicknesses and surface states and can be used in scientific research and the electronics industry.

  2. Measurement of uranium dioxide thermophysical properties by the laser flash method

    Grossi, Pablo Andrade; Ferreira, Ricardo Alberto Neto; Camarano, Denise das Merces; Andrade, Roberto Marcio de

    2009-01-01

    The evaluation of the thermophysical properties of uranium dioxide (UO 2 ), including a reliable uncertainty assessment, are required by the nuclear reactor design. These important information are used by thermohydraulic codes to define operational aspects and to assure the safety, when analyzing various potential situations of accident. The laser flash method had become the most popular method to measure the thermophysical properties of materials. Despite its several advantages, some experimental obstacles have been found due to the difficulty to obtain experimentally the ideals initial and boundary conditions required by the original method. An experimental apparatus and a methodology for estimating uncertainties of thermal diffusivity, thermal conductivity and specific heat measurements based on the laser flash method are presented. A stochastic thermal diffusion modeling has been developed and validated by standard samples. Inverse heat conduction problems (IHCPs) solved by finite volumes technique were applied to the measurement process with real initial and boundary conditions, and Monte Carlo Method was used for propagating the uncertainties. The main sources of uncertainty were due to: pulse time, laser power, thermal exchanges, absorptivity, emissivity, sample thickness, specific mass and dynamic influence of temperature measurement system. As results, mean values and uncertainties of thermal diffusivity, thermal conductivity and specific heat of UO 2 are presented. (author)

  3. Self-calibration method for rotating laser positioning system using interscanning technology and ultrasonic ranging.

    Wu, Jun; Yu, Zhijing; Zhuge, Jingchang

    2016-04-01

    A rotating laser positioning system (RLPS) is an efficient measurement method for large-scale metrology. Due to multiple transmitter stations, which consist of a measurement network, the position relationship of these stations must be first calibrated. However, with such auxiliary devices such as a laser tracker, scale bar, and complex calibration process, the traditional calibration methods greatly reduce the measurement efficiency. This paper proposes a self-calibration method for RLPS, which can automatically obtain the position relationship. The method is implemented through interscanning technology by using a calibration bar mounted on the transmitter station. Each bar is composed of three RLPS receivers and one ultrasonic sensor whose coordinates are known in advance. The calibration algorithm is mainly based on multiplane and distance constraints and is introduced in detail through a two-station mathematical model. The repeated experiments demonstrate that the coordinate measurement uncertainty of spatial points by using this method is about 0.1 mm, and the accuracy experiments show that the average coordinate measurement deviation is about 0.3 mm compared with a laser tracker. The accuracy can meet the requirements of most applications, while the calibration efficiency is significantly improved.

  4. CO2-laser decomposition method of carbonate for AMS 14C measurements

    Kitagawa, Hiroyuki

    2013-01-01

    A CO 2 laser decomposition method enabled the efficient preparation of carbonate samples for AMS 14 C measurement. Samples were loaded in a vacuum chamber and thermally decomposed using laser emission. CO 2 liberated from the carbonate was directly trapped in the cold finger trap of a small CO 2 reduction reactor and graphitized by a hydrogen gas reduction method using catalytic iron powder. The fraction modern values for 0.07–0.57 mg of carbon, obtained from 200 μm-diameter spots of IAEA-C1, varied with sample size in the range of 0.00072 ± 0.00003 to 0.00615 ± 0.00052. The contamination induced by the laser decomposition method and the following graphite handling was estimated to be 0.53 ± 0.21 μg of modern carbon, assuming a constant amount of extraneous carbon contamination. This method could also make it possible to avoid the time-consuming procedures of the conventional acid dissolution method that involves multiple complex steps for the preparation of carbonate samples.

  5. Reflection and diffraction of atomic de Broglie waves by evanescent laser waves. Bare-state method

    Feng, Xiaoping; Witte, N.S.; Hollenberg, C.L.; Opat, G.

    1994-01-01

    Two methods are presented for the investigation of the reflection and diffraction of atoms by gratings formed either by standing or travelling evanescent laser waves. Both methods use the bare-state rather than dressed-state picture. One method is based on the Born series, whereas the other is based on the Laplace transformation of the coupled differential equations. The two methods yield the same theoretical expressions for the reflected and diffracted atomic waves in the whole space including the interaction and the asymptotic regions. 1 ref., 1 fig

  6. Weld quality inspection using laser-EMAT ultrasonic system and C-scan method

    Yang, Lei; Ume, I. Charles

    2014-02-01

    Laser/EMAT ultrasonic technique has attracted more and more interests in weld quality inspection because of its non-destructive and non-contact characteristics. When ultrasonic techniques are used to detect welds joining relative thin plates, the dominant ultrasonic waves present in the plates are Lamb waves, which propagate all through the thickness. Traditional Time of Flight(ToF) method loses its power. The broadband nature of laser excited ultrasound plus dispersive and multi-modal characteristic of Lamb waves make the EMAT acquired signals very complicated in this situation. Challenge rises in interpreting the received signals and establishing relationship between signal feature and weld quality. In this paper, the laser/EMAT ultrasonic technique was applied in a C-scan manner to record full wave propagation field over an area close to the weld. Then the effect of weld defect on the propagation field of Lamb waves was studied visually by watching an movie resulted from the recorded signals. This method was proved to be effective to detect the presence of hidden defect in the weld. Discrete wavelet transform(DWT) was applied to characterize the acquired ultrasonic signals and ideal band-pass filter was used to isolate wave components most sensitive to the weld defect. Different interactions with the weld defect were observed for different wave components. Thus this C-Scan method, combined with DWT and ideal band-pass filter, proved to be an effective methodology to experimentally study interactions of various laser excited Lamb Wave components with weld defect. In this work, the method was demonstrated by inspecting a hidden local incomplete penetration in weld. In fact, this method can be applied to study Lamb Wave interactions with any type of structural inconsistency. This work also proposed a ideal filtered based method to effectively reduce the total experimental time.

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

    Goel, S.; Lohani, B.

    2014-05-01

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

  8. Preparing the image: ground layers in Portuguese painting of 15th and 16th centuries – engraving and preparation

    Vanessa Antunes

    2018-01-01

    Full Text Available The study of the ground layers in ancient painting covers different aspects of its production stages. One of the phases, which we will explore in this text, is the adequacy of the ground layer to receive the drawing. With this aim we made an approach to the type of drawing found in some of the works studied by identifying certain technical issues established in prints from metal engraving technique, with Northern European influences. Ground layers are mostly composed of calcium sulfate, mainly anhydrite in the case of gesso grosso, with addition of calcium carbonate grains in order to smooth the surface of the drawing and painting, or dihydrated gypsum, gesso mate or "gesso sottile", which alone provides the ideal smoothness and fineness to receive the minutia of the drawn details.

  9. Study on APD real time compensation methods of laser Detection system

    Feng Ying; Zhang He; Zhang Xiangjin; Liu Kun

    2011-01-01

    With the monochromatic and the directional capability of the laser, laser detection system is confidential in anti-jamming. Detection accuracy is improved significantly as the result of laser's good orientation ability. Sensitivity is enhanced as laser's high-brightness characteristic. With the development of laser technology and laser devices, laser detections are developed both in civilian and military areas. In the military field, laser detection system has been widely applied in various types of tactical missiles, the technique is more mature. Because photo detectors receive the backscattering echo signal of target in laser detection system, they are required sensitive enough to weak signal. With APD's salient features of high sensitivity, rapid response speed, high response frequency and low noise equivalent power, etc.; PIN is replaced by APD to improve sensitivity of laser detection system in recent years. The signal magnification is inadequate in laser detection system, the detector output is usually amplified by multistage amplifiers. And then the system noise includes detector noise and latter amplifiers noise. With its high internal gain, APD becomes the primary noise source of receiving system. This point can be attested by analyzing the transfer function of laser detection system receiver. To ensure the system detecting ability, APD noise must be mitigated as low as possible. According to a large number of experiments, the power signal-to-noise (SNR) and the best multiplication factor of APD are mostly affected by background radiation and temperature. In order to make APD operate at state of the best multiplication factor, the optimum bias must be selected due to the actual operating circumstance. Therefore, APD realtime compensation must be adopted. The existing APD compensation includes the constant false alarm rate compensation, the noise compensation and the temperature compensation. The features of these compensations are obtained by analyzing

  10. Study on APD real time compensation methods of laser Detection system

    Feng Ying; Zhang He; Zhang Xiangjin; Liu Kun, E-mail: fy_caimi@163.com [ZNDY of Ministerial Key Laboratory, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2011-02-01

    With the monochromatic and the directional capability of the laser, laser detection system is confidential in anti-jamming. Detection accuracy is improved significantly as the result of laser's good orientation ability. Sensitivity is enhanced as laser's high-brightness characteristic. With the development of laser technology and laser devices, laser detections are developed both in civilian and military areas. In the military field, laser detection system has been widely applied in various types of tactical missiles, the technique is more mature. Because photo detectors receive the backscattering echo signal of target in laser detection system, they are required sensitive enough to weak signal. With APD's salient features of high sensitivity, rapid response speed, high response frequency and low noise equivalent power, etc.; PIN is replaced by APD to improve sensitivity of laser detection system in recent years. The signal magnification is inadequate in laser detection system, the detector output is usually amplified by multistage amplifiers. And then the system noise includes detector noise and latter amplifiers noise. With its high internal gain, APD becomes the primary noise source of receiving system. This point can be attested by analyzing the transfer function of laser detection system receiver. To ensure the system detecting ability, APD noise must be mitigated as low as possible. According to a large number of experiments, the power signal-to-noise (SNR) and the best multiplication factor of APD are mostly affected by background radiation and temperature. In order to make APD operate at state of the best multiplication factor, the optimum bias must be selected due to the actual operating circumstance. Therefore, APD realtime compensation must be adopted. The existing APD compensation includes the constant false alarm rate compensation, the noise compensation and the temperature compensation. The features of these compensations are obtained

  11. Study on APD real time compensation methods of laser Detection system

    Ying, Feng; He, Zhang; Xiangjin, Zhang; Kun, Liu

    2011-02-01

    With the monochromatic and the directional capability of the laser, laser detection system is confidential in anti-jamming. Detection accuracy is improved significantly as the result of laser's good orientation ability. Sensitivity is enhanced as laser's high-brightness characteristic. With the development of laser technology and laser devices, laser detections are developed both in civilian and military areas. In the military field, laser detection system has been widely applied in various types of tactical missiles, the technique is more mature. Because photo detectors receive the backscattering echo signal of target in laser detection system, they are required sensitive enough to weak signal. With APD's salient features of high sensitivity, rapid response speed, high response frequency and low noise equivalent power, etc.; PIN is replaced by APD to improve sensitivity of laser detection system in recent years. The signal magnification is inadequate in laser detection system, the detector output is usually amplified by multistage amplifiers. And then the system noise includes detector noise and latter amplifiers noise. With its high internal gain, APD becomes the primary noise source of receiving system. This point can be attested by analyzing the transfer function of laser detection system receiver. To ensure the system detecting ability, APD noise must be mitigated as low as possible. According to a large number of experiments, the power signal-to-noise (SNR) and the best multiplication factor of APD are mostly affected by background radiation and temperature. In order to make APD operate at state of the best multiplication factor, the optimum bias must be selected due to the actual operating circumstance. Therefore, APD realtime compensation must be adopted. The existing APD compensation includes the constant false alarm rate compensation, the noise compensation and the temperature compensation. The features of these compensations are obtained by analyzing

  12. Methods for slow axis beam quality improvement of high power broad area diode lasers

    An, Haiyan; Xiong, Yihan; Jiang, Ching-Long J.; Schmidt, Berthold; Treusch, Georg

    2014-03-01

    For high brightness direct diode laser systems, it is of fundamental importance to improve the slow axis beam quality of the incorporated laser diodes regardless what beam combining technology is applied. To further advance our products in terms of increased brightness at a high power level, we must optimize the slow axis beam quality despite the far field blooming at high current levels. The later is caused predominantly by the built-in index step in combination with the thermal lens effect. Most of the methods for beam quality improvements reported in publications sacrifice the device efficiency and reliable output power. In order to improve the beam quality as well as maintain the efficiency and reliable output power, we investigated methods of influencing local heat generation to reduce the thermal gradient across the slow axis direction, optimizing the built-in index step and discriminating high order modes. Based on our findings, we have combined different methods in our new device design. Subsequently, the beam parameter product (BPP) of a 10% fill factor bar has improved by approximately 30% at 7 W/emitter without efficiency penalty. This technology has enabled fiber coupled high brightness multi-kilowatt direct diode laser systems. In this paper, we will elaborate on the methods used as well as the results achieved.

  13. Towards a novel laser-driven method of exotic nuclei extraction−acceleration for fundamental physics and technology

    Nishiuchi, M., E-mail: sergei@jaea.go.jp; Sakaki, H.; Esirkepov, T. Zh. [Japan Atomic Energy Agency, Kansai Photon Science Institute (Japan); Nishio, K. [Japan Atomic Energy Agency, Advanced Science Research Center (Japan); Pikuz, T. A.; Faenov, A. Ya. [Japan Atomic Energy Agency, Kansai Photon Science Institute (Japan); Skobelev, I. Yu. [Russian Academy of Sciences, Joint Institute for High Temperature (Russian Federation); Orlandi, R. [Japan Atomic Energy Agency, Advanced Science Research Center (Japan); Pirozhkov, A. S.; Sagisaka, A.; Ogura, K.; Kanasaki, M.; Kiriyama, H.; Fukuda, Y. [Japan Atomic Energy Agency, Kansai Photon Science Institute (Japan); Koura, H. [Japan Atomic Energy Agency, Advanced Science Research Center (Japan); Kando, M. [Japan Atomic Energy Agency, Kansai Photon Science Institute (Japan); Yamauchi, T. [Graduate School of Maritime Sciences (Japan); Watanabe, Y. [Kyushu University, Interdisciplinary Graduate School of Engineering Sciences (Japan); Bulanov, S. V., E-mail: svbulanov@gmail.com; Kondo, K. [Japan Atomic Energy Agency, Kansai Photon Science Institute (Japan); and others

    2016-04-15

    A combination of a petawatt laser and nuclear physics techniques can crucially facilitate the measurement of exotic nuclei properties. With numerical simulations and laser-driven experiments we show prospects for the Laser-driven Exotic Nuclei extraction–acceleration method proposed in [M. Nishiuchi et al., Phys, Plasmas 22, 033107 (2015)]: a femtosecond petawatt laser, irradiating a target bombarded by an external ion beam, extracts from the target and accelerates to few GeV highly charged short-lived heavy exotic nuclei created in the target via nuclear reactions.

  14. Experimental method for laser-driven flyer plates for 1-D shocks

    Paisley, D. L.; Luo, S. N.; Swift, D. C.; Loomis, E.; Johnson, R.; Greenfield, S.; Peralta, P.; Koskelo, A.; Tonks, D.

    2007-01-01

    One-dimensional shocks can be generated by impacting flyer plates accelerated to terminal velocities by a confined laser-ablated plasma. Over the past few years, we have developed this capability with our facility-size laser, TRIDENT, capable of ≥500 Joules at multi-microsecond pulse lengths to accelerate 1-D flyer plates, 8-mm diameter by 0.1-2 mm thick. Plates have been accelerated to terminal velocities of 100 to ≥500 m/s, with full recovery of the flyer and target for post mortem metallography. By properly tailoring the laser temporal and spatial profile, the expanding confined plasma accelerates the plate away from the transparent sapphire substrate, and decouples the laser parameters from shock pressure profile resulting from the plate impact on a target. Since the flyer plate is in free flight on impact with the target, minimal collateral damage occurs to either. The experimental method to launch these plates to terminal velocity, ancillary diagnostics, and representative experimental data is presented

  15. Laser tattoo removal as an ablation process monitored by acoustical and optical methods

    Cencič, Boris; Gregorčič, Peter; Možina, Janez; Jezeršek, Matija

    2013-07-01

    Strength of the laser-tissue interaction varies even within a single tattoo because of the inhomogeneous distribution of the tattoo pigment embedded in the skin. A monitoring system is therefore developed for simultaneous monitoring of the laser tattoo removal process based on acoustical and optical techniques. A laser-beam-deflection probe is used for measuring the acoustical signals accompanying the breakdown, and a CCD camera captures the level and the spatial distribution of the plasma radiation. Using these methods we examine the degree of excitation-pulse absorption within the pigment and the degree of the structural changes of the skin. A Nd:YAG laser with a top-hat beam profile, designed for tattoo removal, is used as the excitation source in our experiments. Special attention is given to structural changes in the skin, which depend on the applied fluence. Tattoo removal with multiple pulses is also analyzed. Experiments are made in vitro (skin phantoms) and ex vivo (marking tattoos on the pig skin). The presented results are important for the understanding and optimization of the process used in medical therapies.

  16. Higher-order interactions in molecular collisions studied by a novel laser spectroscopic method

    Kajita, M.; Tachikawa, M.; Shimizu, T.

    1986-01-01

    This is the first systematic experiment to study the characteristics of the dipole-quadrupole and dipole-induced dipole interactions as well as the dipole-dipole interaction. The authors developed a new method to measure the relaxation rate constant of a weak IR transition. The absorption cell is introduced inside the CO/sub 2/ laser cavity to improve sensitivity. The transient oscillation superimposed on the cw laser output is observed when the Stark pulse is applied to the absorbing molecules. The absorption increases when the better coincidence between the laser and absorption lines is obtained by application of the Stark voltage. The absorption decreases for a larger Stark voltage. The sign of the signal depends on whether the absorption intensity increases or decreases due to the Stark field. Since pressure broadening modifies the absorption line shape, the sign of the signal changes when the pressure is increased. The relaxation rate constant can be determined by observing the sign of the signal. The experiment is performed with the frequency coincidence between the CH/sub 3/CN ν/sub 7//sup r/ R(6.6) line and the CO/sub 2/ laser 9.4-μm R(22) line. The relaxation rate constants against various foreign gas molecules (polar molecules, nonpolar linear molecules, and spherical atoms and molecules) have been determined

  17. The Brief Introduction of Different Laser Diagnostics Methods Used in Aeroengine Combustion Research

    Fei Xing

    2016-01-01

    Full Text Available Combustion test diagnosis has always been one of the most important technologies for the development of aerospace engineering. The traditional methods of measurement have been unable to meet the requirements of accurate capture of the flow field in the development process of the aeroengine combustor. Therefore, the development of high-precision measurement and diagnostic techniques to meet the needs of the aeroengine combustor design is imperative. Laser diagnostics techniques developed quickly in the past several years. They are used to measure the parameters of the combustion flow field such as velocity, temperature, and components concentration with high space and time resolution and brought no disturbance. Planar laser-induced fluorescence, coherent anti-Stokes Raman scattering, tunable diode laser absorption spectroscopy, and Raman scattering were introduced systemically in this paper. After analysis of their own advantages and disadvantages, the authors considered validated Raman scattering system and Tunable Diode Laser Absorption Tomography are more suitable for research activities on aeroengine combustion systems.

  18. Methods and considerations to determine sphere center from terrestrial laser scanner point cloud data

    Rachakonda, Prem; Muralikrishnan, Bala; Lee, Vincent; Shilling, Meghan; Sawyer, Daniel; Cournoyer, Luc; Cheok, Geraldine

    2017-01-01

    The Dimensional Metrology Group at the National Institute of Standards and Technology is performing research to support the development of documentary standards within the ASTM E57 committee. This committee is addressing the point-to-point performance evaluation of a subclass of 3D imaging systems called terrestrial laser scanners (TLSs), which are laser-based and use a spherical coordinate system. This paper discusses the usage of sphere targets for this effort, and methods to minimize the errors due to the determination of their centers. The key contributions of this paper include methods to segment sphere data from a TLS point cloud, and the study of some of the factors that influence the determination of sphere centers. (paper)

  19. A method of atmospheric density measurements during Shuttle entry using UV laser Rayleigh scattering

    Mckenzie, Robert L.

    1987-01-01

    A detailed study is described of the performance capabilities and the hardware requirements for a method in which ambient density is measured along the Space Shuttle flight path using on-board optical instrumentation. The technique relies on Rayleigh scattering of light from a pulsed, ultraviolet, ArF excimer laser operating at a wavelength of 193 nm. The method is shown to be capable of providing direct measurements of ambient density with an uncertainty of less than 1 percent and with a spatial resolution of 1 km, over an altitude range from 50 to 90 km. In addition, extensions of this concept are discussed that allow measurements of the shock wave location and the density profile within the shock layer. Two approaches are identified that appear to be feasible, in which the same laser system is used for the extended measurements as that required for the ambient density measurements.

  20. Characteristic analysis of laser isotope separation process by two-step photodissociation method

    Okamoto, Tsuyoshi; Suzuki, Atsuyuki; Kiyose, Ryohei

    1981-01-01

    A large number of laser isotope separation experiments have been performed actively in many countries. In this paper, the selective two-step photodissociation method is chosen and simultaneous nonlinear differential equations that express the separation process are solved directly by using computer. Predicted separation factors are investigated in relation to the incident pulse energy and the concentration of desired molecules. Furthermore, the concept of separative work is used to evaluate the results of separation for this method. It is shown from an example of numerical calculation that a very large separation factor can be obtained if the concentration of desired molecules is lowered and two laser pulses to be closely synchronized are not always required in operation for the photodissociation of molecules. (author)

  1. Systems and methods for imaging using radiation from laser produced plasmas

    Renard-Le Galloudec, Nathalie; Cowan, Thomas E.; Sentoku, Yasuhiko; Rassuchine, Jennifer

    2009-06-30

    In particular embodiments, the present disclosure provides systems and methods for imaging a subject using radiation emitted from a laser produced plasma generating by irradiating a target with a laser. In particular examples, the target includes at least one radiation enhancing component, such as a fluor, cap, or wire. In further examples, the target has a metal layer and an internal surface defining an internal apex, the internal apex of less than about 15 .mu.m, such as less than about 1 .mu.m. The targets may take a variety of shapes, including cones, pyramids, and hemispheres. Certain aspects of the present disclosure provide improved imaging of a subject, such as improved medical images of a radiation dose than typical conventional methods and systems.

  2. Implementing New Methods of Laser Marking of Items in the Nuclear Material Control and Accountability System at SSC RF-IPPE: An Automated Laser Marking System

    Regoushevsky, V.I.; Tambovtsev, S.D.; Dvukhsherstnov, V.G.; Efimenko, V.F.; Ilyantsev, A.I.; Russ, G.P. III

    2009-01-01

    For over ten years SSC RF-IPPE, together with the US DOE National Laboratories, has been working on implementing automated control and accountability methods for nuclear materials and other items. Initial efforts to use adhesive bar codes or ones printed (painted) onto metal revealed that these methods were inconvenient and lacked durability under operational conditions. For NM disk applications in critical stands, there is the additional requirement that labels not affect the neutron characteristics of the critical assembly. This is particularly true for the many stainless-steel clad disks containing highly enriched uranium (HEU) and plutonium that are used at SSC RF-IPPE for modeling nuclear power reactors. In search of an alternate method for labeling these disks, we tested several technological options, including laser marking and two-dimensional codes. As a result, the method of laser coloring was chosen in combination with Data Matrix ECC200 symbology. To implement laser marking procedures for the HEU disks and meet all the nuclear material (NM) handling standards and rules, IPPE staff, with U.S. technical and financial support, implemented an automated laser marking system; there are also specially developed procedures for NM movements during laser marking. For the laser marking station, a Zenith 10F system by Telesis Technologies (10 watt Ytterbium Fiber Laser and Merlin software) is used. The presentation includes a flowchart for the automated system and a list of specially developed procedures with comments. Among other things, approaches are discussed for human-factor considerations. To date, markings have been applied to numerous steel-clad HEU disks, and the work continues. In the future this method is expected to be applied to other MC and A items.

  3. Method for biological tissue temperature measuring in the area of laser radiation exposure with a small size beam profile during laser welding

    Ryabkin, Dmitrii I.

    2018-04-01

    Connection is not strong enough In case of insufficient or excessive temperature of the laser welding. As a result, the temperature measurement in laser welding is an important problem. Measurement area surface is small (3.12 mm2) and measurements shall be carried out by a Non-contact method, which makes them challenging. Method of temperature measurement by an infrared sensor in two positions has been offered. This method allows you to measure the temperature at a distance of up to 5 cm from the measured area with an accuracy of 8%.

  4. Integration of image exposure time into a modified laser speckle imaging method

    RamIrez-San-Juan, J C; Salazar-Hermenegildo, N; Ramos-Garcia, R; Munoz-Lopez, J [Optics Department, INAOE, Puebla (Mexico); Huang, Y C [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA (United States); Choi, B, E-mail: jcram@inaoep.m [Beckman Laser Institute and Medical Clinic, University of California, Irvine, CA (United States)

    2010-11-21

    Speckle-based methods have been developed to characterize tissue blood flow and perfusion. One such method, called modified laser speckle imaging (mLSI), enables computation of blood flow maps with relatively high spatial resolution. Although it is known that the sensitivity and noise in LSI measurements depend on image exposure time, a fundamental disadvantage of mLSI is that it does not take into account this parameter. In this work, we integrate the exposure time into the mLSI method and provide experimental support of our approach with measurements from an in vitro flow phantom.

  5. Integration of image exposure time into a modified laser speckle imaging method

    RamIrez-San-Juan, J C; Salazar-Hermenegildo, N; Ramos-Garcia, R; Munoz-Lopez, J; Huang, Y C; Choi, B

    2010-01-01

    Speckle-based methods have been developed to characterize tissue blood flow and perfusion. One such method, called modified laser speckle imaging (mLSI), enables computation of blood flow maps with relatively high spatial resolution. Although it is known that the sensitivity and noise in LSI measurements depend on image exposure time, a fundamental disadvantage of mLSI is that it does not take into account this parameter. In this work, we integrate the exposure time into the mLSI method and provide experimental support of our approach with measurements from an in vitro flow phantom.

  6. Endoscopic laser-induced steam generator: a new method of treatment for early gastric cancer

    Hayashi, Takuya; Arai, Tsunenori; Tajiri, Hisao; Nogami, Yashiroh; Hino, Kunihiko; Kikuchi, Makoto

    1996-05-01

    The minimum invasive endoscopic treatment for early gastric cancer has been popular in Japan. The endoscopic mucosal resection and laser coagulation by Nd:YAG laser irradiation has been the popular treatment method in this field. However, the submucosal cancer has not been successfully treated by these methods. To treat the submucosal cancer endoscopically, we developed a new coagulation therapy using hot steam generated by Nd:YAG laser. The steam of which temperature was over 10 deg. in Celsius was generated by the laser power of 30 W with 5 ml/min. of saline. The steam was emitted to canine gastric wall under laparotomy or endoscopy for 50 s respectively. Follow up endoscopy was performed on 3, 7, 14, 28 days after the treatment. Histological examination was studied on 7, 28 days, and just after the emission. In the acute observation, the submucosal layer was totally coagulated. On the 7th day, ulceration with white coat was seen. The mucosal defect, submucosal coagulation, and marked edema without muscle degeneration were found by the histological study. On the 14th day, the ulcer advanced in the scar stage. On the 28th day, it completely healed into white scar with mucosal regeneration and mucosal muscle thickening. We could obtain reproducible coagulation up to deep submucosal layer with large area in a short operation time. Moreover there were no degeneration of proper muscle. This treatment effectiveness could be easily controlled by the steam temperature and emission duration. We think that this method can be applied to early gastric cancer including the submucosal cancer, in particular poor risk case for operation. Further study should be done to apply this method to clinical therapy.

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

    Tolker-Nielsen, Tim; Sternberg, Claus

    2014-01-01

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

  8. A new automatic design method to develop multilayer thin film devices for high power laser applications

    Sahoo, N.K.; Apparao, K.V.S.R.

    1992-01-01

    Optical thin film devices play a major role in many areas of frontier technology like development of various laser systems to the designing of complex and precision optical systems. Design and development of these devices are really challenging when they are meant for high power laser applications. In these cases besides desired optical characteristics, the devices are expected to satisfy a whole range of different needs like high damage threshold, durability etc. In the present work a novel completely automatic design method based on Modified Complex Method has been developed for designing of high power thin film devices. Unlike most of the other methods it does not need any suitable starting design. A quarterwave design is sufficient to start with. If required, it is capable of generating its own starting design. The computer code of the method is very simple to implement. This report discusses this novel automatic design method and presents various practicable output designs generated by it. The relative efficiency of the method along with other powerful methods has been presented while designing a broadband IR antireflection coating. The method is also incorporated with 2D and 3D electric field analysis programmes to produce high damage threshold designs. Some experimental devices developed using such designs are also presented in the report. (author). 36 refs., 41 figs

  9. A new systematic calibration method of ring laser gyroscope inertial navigation system

    Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Xiong, Zhenyu; Long, Xingwu

    2016-10-01

    Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.

  10. Thermal Diffusivity Measurement for Thermal Spray Coating Attached to Substrate Using Laser Flash Method

    Akoshima, Megumi; Tanaka, Takashi; Endo, Satoshi; Baba, Tetsuya; Harada, Yoshio; Kojima, Yoshitaka; Kawasaki, Akira; Ono, Fumio

    2011-11-01

    Ceramic-based thermal barrier coatings are used as heat and wear shields of gas turbine blades. There is a strong need to evaluate the thermal conductivity of coating for thermal design and use. The thermal conductivity of a bulk material is obtained as the product of thermal diffusivity, specific heat capacity, and density above room temperature in many cases. Thermal diffusivity and thermal conductivity are unique for a given material because they are sensitive to the structure of the material. Therefore, it is important to measure them in each sample. However it is difficult to measure the thermal diffusivity and thermal conductivity of coatings because coatings are attached to substrates. In order to evaluate the thermal diffusivity of a coating attached to the substrate, we have examined the laser flash method with the multilayer model on the basis of the response function method. We carried out laser flash measurements in layered samples composed of a CoNiCrAlY bond coating and a 8YSZ top coating by thermal spraying on a Ni-based superalloy substrate. It was found that the procedure using laser flash method with the multilayer model is useful for the thermal diffusivity evaluation of a coating attached to a substrate.

  11. Measurement of liquid sheet using laser tagging method by photochromic dye

    Rosli, Nurrina Binti; Amagai, Kenji

    2014-12-01

    Liquid atomization system has been extensively applied as the most significant process in many industrial fields. In the internal combustion engine, the combustion phenomenon is strongly influenced by the spray characteristics of the fuel given by the atomization process. In order to completely understand the whole atomization process, a detail investigation of relations between the liquid jet characteristics and the breakup phenomenon is required. In this study, a non-intrusive method called as laser tagging method by photochromic dye has been developed with aim to study the breakup process of liquid sheet in detail, covering from the behavior in film until disintegrated into ligament and droplets. The laser tagging method by photochromic dye is based on a shift in the absorption spectrum of photochromic dye molecules tagged by ultraviolet laser. The shift results a color change at the tagged region of liquid containing the dye. In this study, the motions of the dye traces were analyzed as the liquid surface velocity. As a result, liquid sheet was found to keep its velocity constantly in film before suddenly increase around broken point. However, it then decreased after broken into droplets. By forming a set of four points of dye traces on the liquid sheet, the change of relative position of the set enabled the measurement of deformation and rotational motion of the liquid sheet. As a result, the normal strain of the liquid sheet parallel to the flow direction depended on the flow behavior of ligament formation.

  12. A method for the formation of Pt metal nanoparticle arrays using nanosecond pulsed laser dewetting

    Owusu-Ansah, Ebenezer; Horwood, Corie A.; Birss, Viola I.; Shi, Yujun J., E-mail: shiy@ucalgary.ca [Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); El-Sayed, Hany A. [Institute for Technical Electrochemistry, Technische Universität München, D-85748 Garching (Germany)

    2015-05-18

    Nanosecond pulsed laser dewetting of Pt thin films, deposited on a dimpled Ta (DT) surface, has been studied here in order to form ordered Pt nanoparticle (NP) arrays. The DT substrate was fabricated via a simple electrochemical anodization process in a highly concentrated H{sub 2}SO{sub 4} and HF solution. Pt thin films (3–5 nm) were sputter coated on DT and then dewetted under vacuum to generate NPs using a 355 nm laser radiation (6–9 ns, 10 Hz). The threshold laser fluence to fully dewet a 3.5 nm thick Pt film was determined to be 300 mJ/cm{sup 2}. Our experiments have shown that shorter irradiation times (≤60 s) produce smaller nanoparticles with more uniform sizes, while longer times (>60 s) give large nanoparticles with wider size distributions. The optimum laser irradiation time of 1 s (10 pulses) has led to the formation of highly ordered Pt nanoparticle arrays with an average nanoparticle size of 26 ± 3 nm with no substrate deformation. At the optimum condition of 1 s and 500 mJ/cm{sup 2}, as many as 85% of the dewetted NPs were found neatly in the well-defined dimples. This work has demonstrated that pulsed laser dewetting of Pt thin films on a pre-patterned dimpled substrate is an efficient and powerful technique to produce highly ordered Pt nanoparticle arrays. This method can thus be used to produce arrays of other high-melting-point metal nanoparticles for a range of applications, including electrocatalysis, functionalized nanomaterials, and analytical purposes.

  13. Porous plasmonic nanocomposites for SERS substrates fabricated by two-step laser method

    Koleva, M.E., E-mail: mihaela_ek@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee blvd., Sofia 1784 (Bulgaria); International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 (Japan); Nedyalkov, N.N.; Atanasov, P.A. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee blvd., Sofia 1784 (Bulgaria); Gerlach, J.W.; Hirsch, D.; Prager, A.; Rauschenbach, B. [Leibniz Institute of Surface Modification (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany); Fukata, N.; Jevasuwan, W. [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 (Japan)

    2016-04-25

    This research is focused on investigation of coupled plasmonic/metal-semiconductor nanomaterials. A two-step laser-assisted method is demonstrated for formation of plasmonic Ag nanoparticles (NPs) distributed into porous metal–oxide semiconductors. The mosaic Ag-ZnO target is used for laser ablation and, subsequently, laser annealing of the deposited layer is applied. The plasmon resonance properties of the nanostructures produced are confirmed by optical transmission spectroscopy. The wurtzite structure of ZnO is formed with tilted c-axis orientation and, respectively, a mixed Raman mode appears at 580 cm{sup −1}. The oxygen pressure applied during a deposition process has impact on the morphology and thickness of the porous nanostructures, but not on the size and size distribution of AgNPs. The porous nanocomposites exhibited potential for SERS applications, most pronounced for the oxygen deficient sample, grown at lower oxygen pressure. The observed considerable SERS enhancement of R6G molecules on AgNP/ZnO can be attributed to the ZnO-to-molecule charge transfer contribution, enhanced by the additional electrons from the local surface plasmon resonance (LSPR) of AgNPs to the ZnO through the conduction band. - Highlights: • Porous AgNPs/ZnO composites are obtained by laser deposition and laser annealing. • Morphology and properties depend on growth oxygen pressure. • The emergence of mixed-symmetry Raman mode at 580 cm{sup −1} is registered. • The AgNPs/ZnO porous nanocomposites are suitable for SERS-active substrates. • The charge transfer enhanced by LSPR has a contribution to SERS effect.

  14. The comparison of laser surface designing and pigment printing methods for the product quality

    Ozguney, Arif Taner

    2007-07-01

    Developing new designs by using the computer and transferring the designs that are obtained to textile surfaces will not only increase and facilitate the production in a more practical manner, but also help you create identical designs. This means serial manufacturing of the products at standard quality and increasing their added values. Moreover, creating textile designs using the laser will also contribute to the value of the product as far as the consumer is concerned because it will not cause any wearing off and deformation in the texture of the fabric unlike the other methods. In the system that has been designed, the laser beam at selected wavelength and intensity was directed onto a selected textile surface and a computer-controlled laser beam source was used to change the colour substances on the textile surface. Pigment printing is also used for designing in textile and apparel sector. In this method, designs are transferred to the fabric manually by using dyestuff. In this study, the denim fabric used for the surfacing trial was 100% cotton, with a weft count per centimeter of 20 and a warp count per centimeter of 27, with fabric weight of 458 g/m 2. The first step was to prepare 40 pieces of denim samples, half of which were prepared manually pigment printing and the other half by using the laser beam. After this, some test applications were done. The tensile strength, tensile extension and some fastness values of designed pieces with two methods were compared according to the international standards.

  15. Novel nuclear laser spectroscopy method using superfluid helium for measurement of spins and moments of exotic nuclei

    Furukawa, Takeshi; Wakui, Takashi; Yang, Xiaofei; Fujita, Tomomi; Imamura, Kei; Yamaguchi, Yasuhiro; Tetsuka, Hiroki; Tsutsui, Yoshiki; Mitsuya, Yosuke; Ichikawa, Yuichi; Ishibashi, Yoko; Yoshida, Naoki; Shirai, Hazuki; Ebara, Yuta; Hayasaka, Miki; Arai, Shino; Muramoto, Sosuke

    2013-01-01

    Highlights: • Development of a novel nuclear laser spectroscopy method using superfluid helium. • Observation of the Zeeman resonance with the 85 Rb beam introduced into helium. • Demonstration of deducing the nuclear spins from the observed resonance spectrum. -- Abstract: We have been developing a novel nuclear laser spectroscopy method “OROCHI” for determining spins and moments of exotic radioisotopes. In this method, we use superfluid helium as a stopping material of energetic radioisotope beams and then stopped radioisotope atoms are subjected to in situ laser spectroscopy in superfluid helium. To confirm the feasibility of this method for rare radioisotopes, we carried out a test experiment using a 85 Rb beam. In this experiment, we have successfully measured the Zeeman resonance signals from the 85 Rb atoms stopped in superfluid helium by laser-RF double resonance spectroscopy. This method is efficient for the measurement of spins and moments of more exotic nuclei

  16. Er,Cr:YSGG Laser as a Novel Method for Rebonding Failed Ceramic Brackets.

    Sohrabi, Aydin; Jafari, Sanaz; Kimyai, Soodabeh; Rikhtehgaran, Sahand

    2016-10-01

    Since there is no standard method for rebonding loose ceramic brackets, the aim of this study was to evaluate the possibility of using Er,Cr:YSGG laser to eliminate the remaining composite materials from the base of ceramic brackets and to compare the bond strength of rebonded brackets with the new ones. Sixty-two extracted human premolars were mounted in acrylic cylinders. Thirty-one ceramic brackets were bonded, and shear bond strength was tested using Hounsfield testing machine. The remnants of the bonding material were removed from the bases of brackets using Er,Cr:YSGG laser. These brackets were rebonded to 31 fresh teeth and again shear bond strength was measured. Pattern of debonding was assessed in both cases under a stereomicroscope and graded according to ARI index. Data were analyzed with independent t-test and Fisher's exact test. Mean shear bond strength of the bond and rebond groups was 12.29 ± 5.46 and 10.58 ± 5.16 MPa, respectively. There were no significant differences between the two groups (p = 0.21). Pattern of bond failure was not statistically different between the two groups. Er,Cr:YSGG laser was effective in removing the remnants of bonding material from the base of ceramic brackets without any interference with the ceramic base itself, demonstrating that it might be a suitable method for rebonding ceramic brackets.

  17. Method of surface error visualization using laser 3D projection technology

    Guo, Lili; Li, Lijuan; Lin, Xuezhu

    2017-10-01

    In the process of manufacturing large components, such as aerospace, automobile and shipping industry, some important mold or stamped metal plate requires precise forming on the surface, which usually needs to be verified, if necessary, the surface needs to be corrected and reprocessed. In order to make the correction of the machined surface more convenient, this paper proposes a method based on Laser 3D projection system, this method uses the contour form of terrain contour, directly showing the deviation between the actually measured data and the theoretical mathematical model (CAD) on the measured surface. First, measure the machined surface to get the point cloud data and the formation of triangular mesh; secondly, through coordinate transformation, unify the point cloud data to the theoretical model and calculate the three-dimensional deviation, according to the sign (positive or negative) and size of the deviation, use the color deviation band to denote the deviation of three-dimensional; then, use three-dimensional contour lines to draw and represent every coordinates deviation band, creating the projection files; finally, import the projection files into the laser projector, and make the contour line projected to the processed file with 1:1 in the form of a laser beam, compare the Full-color 3D deviation map with the projection graph, then, locate and make quantitative correction to meet the processing precision requirements. It can display the trend of the machined surface deviation clearly.

  18. Laser Induced Damage of Potassium Dihydrogen Phosphate (KDP Optical Crystal Machined by Water Dissolution Ultra-Precision Polishing Method

    Yuchuan Chen

    2018-03-01

    Full Text Available Laser induced damage threshold (LIDT is an important optical indicator for nonlinear Potassium Dihydrogen Phosphate (KDP crystal used in high power laser systems. In this study, KDP optical crystals are initially machined with single point diamond turning (SPDT, followed by water dissolution ultra-precision polishing (WDUP and then tested with 355 nm nanosecond pulsed-lasers. Power spectral density (PSD analysis shows that WDUP process eliminates the laser-detrimental spatial frequencies band of micro-waviness on SPDT machined surface and consequently decreases its modulation effect on the laser beams. The laser test results show that LIDT of WDUP machined crystal improves and its stability has a significant increase by 72.1% compared with that of SPDT. Moreover, a subsequent ultrasonic assisted solvent cleaning process is suggested to have a positive effect on the laser performance of machined KDP crystal. Damage crater investigation indicates that the damage morphologies exhibit highly thermal explosion features of melted cores and brittle fractures of periphery material, which can be described with the classic thermal explosion model. The comparison result demonstrates that damage mechanisms for SPDT and WDUP machined crystal are the same and WDUP process reveals the real bulk laser resistance of KDP optical crystal by removing the micro-waviness and subsurface damage on SPDT machined surface. This improvement of WDUP method makes the LIDT more accurate and will be beneficial to the laser performance of KDP crystal.

  19. 2D modeling of direct laser metal deposition process using a finite particle method

    Anedaf, T.; Abbès, B.; Abbès, F.; Li, Y. M.

    2018-05-01

    Direct laser metal deposition is one of the material additive manufacturing processes used to produce complex metallic parts. A thorough understanding of the underlying physical phenomena is required to obtain a high-quality parts. In this work, a mathematical model is presented to simulate the coaxial laser direct deposition process tacking into account of mass addition, heat transfer, and fluid flow with free surface and melting. The fluid flow in the melt pool together with mass and energy balances are solved using the Computational Fluid Dynamics (CFD) software NOGRID-points, based on the meshless Finite Pointset Method (FPM). The basis of the computations is a point cloud, which represents the continuum fluid domain. Each finite point carries all fluid information (density, velocity, pressure and temperature). The dynamic shape of the molten zone is explicitly described by the point cloud. The proposed model is used to simulate a single layer cladding.

  20. Evaluation of thermal shock strengths for graphite materials using a laser irradiation method

    Kim, Jae Hoon; Lee, Young Shin; Kim, Duck Hoi; Park, No Seok; Suh, Jeong; Kim, Jeng O.; Il Moon, Soon

    2004-01-01

    Thermal shock is a physical phenomenon that occurs during the exposure to rapidly high temperature and pressure changes or during quenching of a material. The rocket nozzle throat is exposed to combustion gas of high temperature. Therefore, it is important to select suitable materials having the appropriate thermal shock resistance and to evaluate these materials for rocket nozzle design. The material of this study is ATJ graphite, which is the candidate material for rocket nozzle throat. This study presents an experimental method to evaluate the thermal shock resistance and thermal shock fracture toughness of ATJ graphite using laser irradiation. In particular, thermal shock resistance tests are conducted with changes of specimen thickness, with laser source irradiated at the center of the specimen. Temperature distributions on the specimen surface are detected using type K and C thermocouples. Scanning electron microscope (SEM) is used to observe the thermal cracks on specimen surface

  1. [Physical treatment methods for acne. Light, laser, photodynamic therapy and peeling].

    Borelli, C; Korting, H C

    2010-02-01

    The medical treatment of acne is generally sufficient to meet the expectations of acne patients. However, in a number of situations additional therapeutic approaches may be advisable. There are a wide variety of useful physical methods. They range from electromagnetic waves, usually light, to peeling and manual therapy. Phototherapy of acne includes not just visible light but also laser and flash lamp therapy. The present review provides an overview on the evidence. Visible light, in particular blue light, provides an effective option for treatment of inflammatory acne. Photodynamic therapy also is efficacious; however, it should not be used because of an unfavorable risk-benefit ratio. UV treatment of acne is obsolete. Newer studies on the use of a variety of laser systems and flash lamps have demonstrated in part rewarding results.

  2. Method for Cleaning Laser-Drilled Holes on Printed Wiring Boards by Plasma Treatment

    Hirogaki, Toshiki; Aoyama, Eiichi; Minagi, Ryu; Ogawa, Keiji; Katayama, Tsutao; Matsuoka, Takashi; Inoue, Hisahiro

    We propose a new method for cleaning blind via holes after laser drilling of PWBs using oxygen plasma treatment. This report dealt with three kinds of PWB materials: epoxy resin and two kinds of aramid fiber reinforced plastics (AFRP: Technora or Kevlar fiber reinforcement). We observed the drilled holes after plasma treatment using both an optical and a scanning electric microscope (SEM). It was confirmed that adequate etching took place in the drilled holes by plasma treatment. We also compared the hole wall and hole bottom after plasma treatment with ones after chemical etching. It was clear that there was no damage to the aramid fiber tip on the hole wall, and that a smooth roughness of the hole wall was obtained by means of plasma treatment. As a result, we demonstrated that the plasma treatment is effective in cleaning the laser drilled holes of PWBs.

  3. Modification of the laser triangulation method for measuring the thickness of optical layers

    Khramov, V. N.; Adamov, A. A.

    2018-04-01

    The problem of determining the thickness of thin films by the method of laser triangulation is considered. An expression is derived for the film thickness and the distance between the focused beams on the photo detector. The possibility of applying the chosen method for measuring thickness is in the range [0.1; 1] mm. We could resolve 2 individual light marks for a minimum film thickness of 0.23 mm. We resolved with the help of computer processing of photos with a resolution of 0.10 mm. The obtained results can be used in ophthalmology for express diagnostics during surgical operations on the corneal layer.

  4. Detection of white spot lesions by segmenting laser speckle images using computer vision methods.

    Gavinho, Luciano G; Araujo, Sidnei A; Bussadori, Sandra K; Silva, João V P; Deana, Alessandro M

    2018-05-05

    This paper aims to develop a method for laser speckle image segmentation of tooth surfaces for diagnosis of early stages caries. The method, applied directly to a raw image obtained by digital photography, is based on the difference between the speckle pattern of a carious lesion tooth surface area and that of a sound area. Each image is divided into blocks which are identified in a working matrix by their χ 2 distance between block histograms of the analyzed image and the reference histograms previously obtained by K-means from healthy (h_Sound) and lesioned (h_Decay) areas, separately. If the χ 2 distance between a block histogram and h_Sound is greater than the distance to h_Decay, this block is marked as decayed. The experiments showed that the method can provide effective segmentation for initial lesions. We used 64 images to test the algorithm and we achieved 100% accuracy in segmentation. Differences between the speckle pattern of a sound tooth surface region and a carious region, even in the early stage, can be evidenced by the χ 2 distance between histograms. This method proves to be more effective for segmenting the laser speckle image, which enhances the contrast between sound and lesioned tissues. The results were obtained with low computational cost. The method has the potential for early diagnosis in a clinical environment, through the development of low-cost portable equipment.

  5. Laser speckle imaging of rat retinal blood flow with hybrid temporal and spatial analysis method

    Cheng, Haiying; Yan, Yumei; Duong, Timothy Q.

    2009-02-01

    Noninvasive monitoring of blood flow in retinal circulation will reveal the progression and treatment of ocular disorders, such as diabetic retinopathy, age-related macular degeneration and glaucoma. A non-invasive and direct BF measurement technique with high spatial-temporal resolution is needed for retinal imaging. Laser speckle imaging (LSI) is such a method. Currently, there are two analysis methods for LSI: spatial statistics LSI (SS-LSI) and temporal statistical LSI (TS-LSI). Comparing these two analysis methods, SS-LSI has higher signal to noise ratio (SNR) and TSLSI is less susceptible to artifacts from stationary speckle. We proposed a hybrid temporal and spatial analysis method (HTS-LSI) to measure the retinal blood flow. Gas challenge experiment was performed and images were analyzed by HTS-LSI. Results showed that HTS-LSI can not only remove the stationary speckle but also increase the SNR. Under 100% O2, retinal BF decreased by 20-30%. This was consistent with the results observed with laser Doppler technique. As retinal blood flow is a critical physiological parameter and its perturbation has been implicated in the early stages of many retinal diseases, HTS-LSI will be an efficient method in early detection of retina diseases.

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

    Taekjun Oh

    2015-07-01

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

  7. Trade of engravings and books between Rome and Spain at the end of the 16th century: the case of the Italian merchant Antonio Pisano

    María Josefa Tarifa Castilla

    2017-03-01

    Full Text Available This study reveals the arrival of prints and books to the North of Spain acquired by the Italian merchant Antonio Pisano in Rome during a trip of 1582-1583. The voyage was financed thanks to the temporary commercial company established between Pisano and the Genoese Juan Luis de Musante, royal master-builder to Felipe II in Navarre, and both residents in Pamplona. The works include engravings of sacred and profane themes by the most important engravers of the epoch, such as the Dutch Cornelis Cort and the Mantuans Adamo and Diana Ghisi, in addition to books of figures, some by outstanding artists such as Michelangelo or Polidoro da Caravaggio.

  8. Cutting of nonmetallic materials using Nd:YAG laser beam

    Bashir Ahmed Tahir; Rashid Ahmed; M. G. B. Ashiq; Afaq Ahmed; M. A. Saeed

    2012-01-01

    This study deals with Nd:YAG laser cutting nonmetallic materials,which is one of the most important and popular industrial applications of laser.The main theme is to evaluate the effects of Nd:YAG laser beam power besides work piece scanning speed.For approximate cutting depth,a theoretical study is conducted in terms of material property and cutting speed.Results show a nonlinear relation between the cutting depth and input energy.There is no significant effect of speed on cutting depth with the speed being larger than 30 mm/s.An extra energy is utilized in the deep cutting.It is inferred that as the laser power increases,cutting depth increases.The experimental outcomes are in good agreement with theoretical results.This analysis will provide a guideline for laser-based industry to select a suitable laser for cutting,scribing,trimming,engraving,and marking nonmetallic materials.

  9. Cutting of nonmetallic materials using Nd:YAG laser beam

    Tahir, Bashir Ahmed; Ashiq, M.G. B.; Saeed, M.A.; Ahmed, Rashid; Ahmed, Afaq

    2012-01-01

    This study deals with Nd:YAG laser cutting nonmetallic materials, which is one of the most important and popular industrial applications of laser. The main theme is to evaluate the effects of Nd:YAG laser beam power besides work piece scanning speed. For approximate cutting depth, a theoretical study is conducted in terms of material property and cutting speed. Results show a nonlinear relation between the cutting depth and input energy. There is no significant effect of speed on cutting depth with the speed being larger than 30 mm/s. An extra energy is utilized in the deep cutting. It is inferred that as the laser power increases, cutting depth increases. The experimental outcomes are in good agreement with theoretical results. This analysis will provide a guideline for laser-based industry to select a suitable laser for cutting, scribing, trimming, engraving, and marking nonmetallic materials. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  10. Highly Controlled Codeposition Rate of Organolead Halide Perovskite by Laser Evaporation Method.

    Miyadera, Tetsuhiko; Sugita, Takeshi; Tampo, Hitoshi; Matsubara, Koji; Chikamatsu, Masayuki

    2016-10-05

    Organolead-halide perovskites can be promising materials for next-generation solar cells because of its high power conversion efficiency. The method of precise fabrication is required because both solution-process and vacuum-process fabrication of the perovskite have problems of controllability and reproducibility. Vacuum deposition process was expected to achieve precise control; however, vaporization of amine compound significantly degrades the controllability of deposition rate. Here we achieved the reduction of the vaporization by implementing the laser evaporation system for the codeposition of perovskite. Locally irradiated continuous-wave lasers on the source materials realized the reduced vaporization of CH 3 NH 3 I. The deposition rate was stabilized for several hours by adjusting the duty ratio of modulated laser based on proportional-integral control. Organic-photovoltaic-type perovskite solar cells were fabricated by codeposition of PbI 2 and CH 3 NH 3 I. A power-conversion efficiency of 16.0% with reduced hysteresis was achieved.

  11. Femtosecond laser surface texturing of titanium as a method to reduce the adhesion of Staphylococcus aureus and biofilm formation

    Cunha, Alexandre; Elie, Anne-Marie; Plawinski, Laurent; Serro, Ana Paula; Botelho do Rego, Ana Maria; Almeida, Amélia; Urdaci, Maria C.; Durrieu, Marie-Christine; Vilar, Rui

    2016-01-01

    The aim of the present work was to investigate the possibility of using femtosecond laser surface texturing as a method to reduce the colonization of Grade 2 Titanium alloy surfaces by Staphylococcus aureus and the subsequent formation of biofilm. The laser treatments were carried out with a Yb:KYW chirped-pulse-regenerative amplification laser system with a central wavelength of 1030 nm and a pulse duration of 500 fs. Two types of surface textures, consisting of laser-induced periodic surface structures (LIPSS) and nanopillars, were produced. The topography, chemical composition and phase constitution of these surfaces were investigated by atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction. Surface wettability was assessed by the sessile drop method using water and diiodomethane as testing liquids. The response of S. aureus put into contact with the laser treated surfaces in controlled conditions was investigated by epifluorescence microscopy and scanning electron microscopy 48 h after cell seeding. The results achieved show that the laser treatment reduces significantly the bacterial adhesion to the surface as well as biofilm formation as compared to a reference polished surfaces and suggest that femtosecond laser texturing is a simple and promising method for endowing dental and orthopedic titanium implants with antibacterial properties, reducing the risk of implant-associated infections without requiring immobilized antibacterial substances, nanoparticles or coatings.

  12. Laser beam uniformity and stability using homogenizer-based fiber optic launch method: square core fiber delivery

    Lizotte, Todd E.

    2011-03-01

    Over the years, technological achievements within the laser medical diagnostic, treatment, and therapy markets have led to ever increasing requirements for greater control of critical laser beam parameters. Increased laser power/energy stabilization, temporal and spatial beam shaping and flexible laser beam delivery systems with ergonomic focusing or imaging lens systems are sought by leading medical laser system producers. With medical procedures that utilize laser energy, there is a constant emphasis on reducing adverse effects that come about by the laser itself or its optical system, but even when these variables are well controlled the medical professional will still need to deal with the multivariate nature of the human body. Focusing on the variables that can be controlled, such as accurate placement of the laser beam where it will expose a surface being treated as well as laser beam shape and uniformity is critical to minimizing adverse conditions. This paper covers the use of fiber optic beam delivery as a means of defining the beam shape (intensity/power distribution uniformity) at the target plane as well as the use of fiber delivery as a means to allow more flexible articulation of the laser beam over the surface being treated. The paper will present a new concept of using a square core fiber beam delivery design utilizing a unique micro lens array (MLA) launch method that improves the overall stability of the system, by minimizing the impact of the laser instability. The resulting performance of the prototype is presented to demonstrate its stability in comparison to simple lens launch techniques, with an emphasis on homogenization and articulated fiber delivery.

  13. Laser reflection method for determination of shear stress in low density transitional flows

    Sathian, Sarith P.; Kurian, Job

    2006-03-01

    The details of laser reflection method (LRM) for the determination of shear stress in low density transitional flows are presented. The method is employed to determine the shear stress due to impingement of a low density supersonic free jet issuing out from a convergent divergent nozzle on a flat plate. The plate is smeared with a thin oil film and kept parallel to the nozzle axis. For a thin oil film moving under the action of aerodynamic boundary layer, the shear stress at the air-oil interface is equal to the shear stress between the surface and air. A direct and dynamic measurement of the oil film slope generated by the shear force is done using a position sensing detector (PSD). The thinning rate of the oil film is directly measured which is the major advantage of the LRM. From the oil film slope history, calculation of the shear stress is done using a three-point formula. The range of Knudsen numbers investigated is from 0.028 to 0.516. Pressure ratio across the nozzle varied from 3,500 to 8,500 giving highly under expanded free jets. The measured values of shear, in the overlapping region of experimental parameters, show fair agreement with those obtained by force balance method and laser interferometric method.

  14. Method for studying gas composition in the human mastoid cavity by use of laser spectroscopy.

    Lindberg, Sven; Lewander, Märta; Svensson, Tomas; Siemund, Roger; Svanberg, Katarina; Svanberg, Sune

    2012-04-01

    We evaluated a method for gas monitoring in the mastoid cavity using tunable diode laser spectroscopy by comparing it to simultaneously obtained computed tomographic (CT) scans. The presented optical technique measures free gases, oxygen (O2), and water vapor (H2O) within human tissue by use of low-power diode lasers. Laser light was sent into the tip of the mastoid process, and the emerging light at the level of the antrum was captured with a detector placed on the skin. The absorption of H2O was used to monitor the probed gas volume of the mastoid cavity, and it was compared to the CT scan-measured volume. The ratio between O2 absorption and H2O absorption estimated the O2 content in the mastoid cavity and thus the ventilation. The parameters were compared to the grading of mastoid cavities based on the CT scans (n = 31). The reproducibility of the technique was investigated by measuring each mastoid cavity 4 times. Both O2 and H2O were detected with good reproducibility. The H2O absorption and the CT volume correlated (r = 0.69). The average ratio between the normalized O2 absorption and the H2O absorption signals was 0.7, indicating a lower O2 content than in surrounding air (expected ratio, 1.0), which is consistent with previous findings made by invasive techniques. All mastoid cavities with radiologic signs of disease were detected. Laser spectroscopy monitoring appears to be a usable tool for noninvasive investigations of gas composition in the mastoid cavity, providing important clinical information regarding size and ventilation.

  15. Application of laser chaos control methods to controlling thyroid-catatonic oscillations and burst firing of dopamine neurons

    Duong-van, Minh

    1993-11-01

    A method of controlling chaotic to laminar flows in the Lorenz equations using fixed points dictated by minimizing the Lyapunov functional was proposed by Singer, Wang and Bau. Using different fixed points, we find that the solutions in a chaotic regime can also be periodic. Since the lasers equations are isomorphic to the Lorenz equations, we use this new method to control chaos when the laser is operated over the pump threshold. Furthermore, by solving the laser equations with an occasional proportional feedback mechanism, we recover the essential lasers controlling features experimentally discovered by Roy, Murphy, Jr., Maier, Gills and Hunt. This method of control chaos is now extended to various medical and biological systems.

  16. Computation of tightly-focused laser beams in the FDTD method.

    Capoğlu, Ilker R; Taflove, Allen; Backman, Vadim

    2013-01-14

    We demonstrate how a tightly-focused coherent TEMmn laser beam can be computed in the finite-difference time-domain (FDTD) method. The electromagnetic field around the focus is decomposed into a plane-wave spectrum, and approximated by a finite number of plane waves injected into the FDTD grid using the total-field/scattered-field (TF/SF) method. We provide an error analysis, and guidelines for the discrete approximation. We analyze the scattering of the beam from layered spaces and individual scatterers. The described method should be useful for the simulation of confocal microscopy and optical data storage. An implementation of the method can be found in our free and open source FDTD software ("Angora").

  17. Review of laser-induced fluorescence methods for measuring rf- and microwave electric fields in discharges

    Gavrilenko, V.; Oks, E.

    1994-01-01

    Development of methods for measuring rf- or μ-wave electric fields E(t) = E 0 cosωt in discharge plasmas is of a great practical importance. First, these are fields used for producing rf- or μ-wave discharges. Second, the fields E(t) may represent electromagnetic waves penetrating into a plasma from the outside. This paper reviews methods for diagnostics of the fields E(t) in low temperature plasmas based on Laser-Induced Fluorescence (LIF). Compared to emission (passive) methods, LIF-methods have a higher sensitivity as well as higher spatial and temporal resolutions. Underlying physical effects may be highlighted by an example of LIF of hydrogen atoms in a plasma. After a presentation of the underlying physical principles, the review focuses on key experiments where these principles were implemented for measurements of rf- and μ-wave electric fields in various discharges

  18. Long distance high power optical laser fiber break detection and continuity monitoring systems and methods

    Rinzler, Charles C.; Gray, William C.; Faircloth, Brian O.; Zediker, Mark S.

    2016-02-23

    A monitoring and detection system for use on high power laser systems, long distance high power laser systems and tools for performing high power laser operations. In particular, the monitoring and detection systems provide break detection and continuity protection for performing high power laser operations on, and in, remote and difficult to access locations.

  19. Mathematical simulation of the thermal diffusion in dentine irradiated with Nd:YAG laser using finite difference method

    Moriyama, Eduardo H.; Zangaro, Renato A.; Lobo, Paulo D. d. C.; Villaverde, Antonio G. J. B.; Watanabe-Sei, Ii; Pacheco, Marcos T. T.; Otsuka, Daniel K.

    2002-06-01

    Thermal damage in dental pulp during Nd:YAG laser irradiation have been studied by several researchers; but due to dentin inhomogeneous structure, laser interaction with dentin in the hypersensitivity treatment are not fully understood. In this work, heat distribution profile on human dentine samples irradiated with Nd:YAG laser was simulated at surface and subjacent layers. Calculations were carried out using the Crank-Nicolson's finite difference method. Sixteen dentin samples with 1,5 mm of thickness were evenly distributed into four groups and irradiated with Nd:YAG laser pulses, according to the following scheme: (I) 1 pulse of 900 mJ, (II) 2 pulses of 450 mJ, (III) 3 pulses of 300 mJ, (IV) 6 pulses of 150 mJ; corresponding to a total laser energy of 900 mJ. The pulse interval was 300ms, the pulse duration of 900 ms and irradiated surface area of 0,005 mm2. Laser induced morphological changes in dentin were observed for all the irradiated samples. The heat distribution throughout the dentin layer, from the external dentin surface to the pulpal chamber wall, was calculated for each case, in order to obtain further information about the pulsed Nd:YAG laser-oral hard tissue interaction. The simulation showed significant differences in the final temperature at the pulpal chamber, depending on the exposition time and the energy contained in the laser pulse.

  20. System and Method for Generating a Frequency Modulated Linear Laser Waveform

    Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)

    2017-01-01

    A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

  1. Polarization switching detection method using a ferroelectric liquid crystal for dichroic atomic vapor laser lock frequency stabilization techniques.

    Dudzik, Grzegorz; Rzepka, Janusz; Abramski, Krzysztof M

    2015-04-01

    We present a concept of the polarization switching detection method implemented for frequency-stabilized lasers, called the polarization switching dichroic atomic vapor laser lock (PSDAVLL) technique. It is a combination of the well-known dichroic atomic vapor laser lock method for laser frequency stabilization with a synchronous detection system based on the surface-stabilized ferroelectric liquid crystal (SSFLC).The SSFLC is a polarization switch and quarter wave-plate component. This technique provides a 9.6 dB better dynamic range ratio (DNR) than the well-known two-photodiode detection configuration known as the balanced polarimeter. This paper describes the proposed method used practically in the VCSEL laser frequency stabilization system. The applied PSDAVLL method has allowed us to obtain a frequency stability of 2.7×10⁻⁹ and a reproducibility of 1.2×10⁻⁸, with a DNR of detected signals of around 81 dB. It has been shown that PSDAVLL might be successfully used as a method for spectra-stable laser sources.

  2. Transformation of medical grade silicone rubber under Nd:YAG and excimer laser irradiation: First step towards a new miniaturized nerve electrode fabrication process

    Dupas-Bruzek, C.; Robbe, O.; Addad, A.; Turrell, S.; Derozier, D.

    2009-01-01

    Medical grade silicone rubber, poly-dimethylsiloxane (PDMS) is a widely used biomaterial. Like for many polymers, its surface can be modified in order to change one or several of its properties which further allow this surface to be functionalized. Laser-induced surface modification of PDMS under ambient conditions is an easy and powerful method for the surface modification of PDMS without altering its bulk properties. In particular, we profit from both UV laser inducing surface modification and of UV laser micromachining to develop a first part of a new process aiming at increasing the number of contacts and tracks within the same electrode surface to improve the nerve selectivity of implantable self sizing spiral cuff electrodes. The second and last part of the process is to further immerse the engraved electrode in an autocatalytic Pt bath leading in a selective Pt metallization of the laser irradiated tracks and contacts and thus to a functionalized PDMS surface. In the present work, we describe the different physical and chemical transformations of a medical grade PDMS as a function of the UV laser and of the irradiation conditions used. We show that the ablation depths, chemical composition, structure and morphology vary with (i) the laser wavelength (using an excimer laser at 248 nm and a frequency-quadrupled Nd:YAG laser at 266 nm), (ii) the conditions of irradiation and (iii) the pulse duration. These different modified properties are expected to have a strong influence on the nucleation and growth rates of platinum which govern the adhesion and the thickness of the Pt layer on the electrodes and thus the DC resistance of tracks.

  3. Progress on CD-DVD laser microfabrication method to develop cell culture scaffolds integrating biomimetic characteristics

    Hautefeuille, Mathieu; Vázquez-Victorio, Genaro; Cruz-Ramírez, Aaron; Cabriales, Lucia; Jiménez-Diaz, Edgar; Escutia-Guadarrama, Lidia; López-Aparicio, Jehú; Pérez-Calixto, Daniel; Cano-Jorge, Mariel; Nieto-Rivera, Brenda; Sánchez-Olvera, Raúl

    2018-02-01

    The development of organ-on-chip and biological scaffolds is currently requiring simpler methods to microstructure biocompatible materials in three dimensions, fabricate structural and functional elements in biomaterials or modify the physicochemical properties of desired substrates. With the aim of creating simple, cost-effective alternatives to conventional existing techniques to produce such platforms with very specific properties, a low-power CD-DVD laser pickup head was recycled and mounted on a programmable three-axis micro-displacement system in order to modify the surface of polymeric materials in a local fashion. Thanks to a specially-designed method using a strongly absorbing additive coating the materials of interest, it has been possible to establish and precisely control processes useful in microtechnology for biomedical applications and normally restricted to much less affordable high-power lasers. In this work, we present our latest progress regarding the application of our fabrication technique to the development of organ-on-chip platforms thanks to the simple integration of several biomimetic characteristics typically achieved with traditional, less cost-effective microtechnology methods in one step or through replica-molding. Our straightforward approach indeed enables great control of local laser microablation for true on-demand biomimetic micropatterned designs in several transparent polymers and hydrogels of tunable stiffness and is allowing integration of microfluidics, microelectronics, optical waveguides, surface microstructuring and even transfer of superficial protein micropatterns on a variety of biocompatible materials. The results presented here were validated using hepatic and fibroblasts cell lines to demonstrate the viability of our procedure for organ-on-chip development and show the impact of such features in cell culture.

  4. Numerical Investigation of Vertical Cavity Lasers With High-Contrast Gratings Using the Fourier Modal Method

    Taghizadeh, Alireza; Mørk, Jesper; Chung, Il-Sug

    2016-01-01

    We explore the use of a modal expansion technique, Fourier modal method (FMM), for investigating the optical properties of vertical cavities employing high-contrast gratings (HCGs). Three techniques for determining the resonance frequency and quality factor (Q-factor) of a cavity mode are compared......, the scattering losses of several HCG-based vertical cavities with inplane heterostructures which have promising prospects for fundamental physics studies and on-chip laser applications, are investigated. This type of parametric study of 3D structures would be numerically very demanding using spatial...

  5. Fringe counting method for synthetic phase with frequency-modulated laser diodes

    Onodera, Ribun; Sakuyama, Munechika; Ishii, Yukihiro

    2007-01-01

    Fringe counting method with laser diodes (LDs) for displacement measurement has been constructed. Two LDs are frequency modulated by mutually inverted sawtooth currents on an unbalanced two-beam interferometer. The mutually inverted sawtooth-current modulation of LDs produces interference fringe signals with opposite signs for respective wavelengths. The two fringe signals are fed to an electronic mixer to produce a synthetic fringe signal with a reduced sensitivity to the synthetic wavelength. Synthetic fringe pulses derived from the synthetic fringe signal make a fringe counting system possible for faster movement of the tested mirror

  6. Transport of nonintrinsic impurities injected by laser blow-off method

    Bakos, J.S.

    1993-09-01

    The transport of nonintrinsic impurities injected by laser blow-off method is theoretically described by solving the two-dimensional (radial and toroidal) time dependent equations of diffusion in the edge plasmas of a tokamak. Explicit expressions and evaluation procedures are given for the calculation of the density profile, temperature profile and the diffusion coefficients for the atoms injected and for the ions formed from the injected atoms from the two-dimensional intensity distribution of line radiation of two sorts of atom and ions formed from the atoms measured by a (matrix) CCD camera time resolved. (orig.)

  7. Laser sampling

    Gorbatenko, A A; Revina, E I

    2015-01-01

    The review is devoted to the major advances in laser sampling. The advantages and drawbacks of the technique are considered. Specific features of combinations of laser sampling with various instrumental analytical methods, primarily inductively coupled plasma mass spectrometry, are discussed. Examples of practical implementation of hybrid methods involving laser sampling as well as corresponding analytical characteristics are presented. The bibliography includes 78 references

  8. Gold nanoparticles and films produced by a laser ablation/gas deposition (LAGD) method

    Kawakami, Yuji; Seto, Takafumi; Yoshida, Toshinobu; Ozawa, Eiichi

    2002-01-01

    Gold nanoparticles have great potential for various nanoelectronic applications such as single electron transistors, an infrared absorption sensor and so on. It is very important to understand and control the size distribution of the particles for such a variety of applications. In this paper, we report the size distribution of gold nanoparticles and the relationship between the nanoparticle-films and the electrical property produced by a laser ablation method. Gold nanoparticle-films were prepared by a technique, which sprays nanoparticles on the substrate through a nozzle. We call it a gas deposition method. The nanoparticles were generated by the nanosecond pulsed Nd:YAG laser ablation of a gold substrate under a low-pressure inert gas atmosphere. The ambient pressure was changed to control the average size and their distribution. The particles produced in the generation chamber were transported by a helium carrier gas to the deposition chamber and deposited on a substrate to form the films composed of gold nanoparticles. The electrical resistivity of the generated gold nanoparticle-films on the glass substrates was measured using a four-probe method. The size distribution of the nanoparticles was examined using transmission electron microscopy (TEM) and a low-pressure differential mobility analyzer (LP-DMA). The relationship between the particle size and the electrical properties of each film made by the different synthesis conditions were analyzed. The electrical resistivity changed from the order of 10 -5 to 10 -1 Ω cm depending on the ambient pressure and the size distribution

  9. An optimization method for defects reduction in fiber laser keyhole welding

    Ai, Yuewei; Jiang, Ping; Shao, Xinyu; Wang, Chunming; Li, Peigen; Mi, Gaoyang; Liu, Yang; Liu, Wei

    2016-01-01

    Laser welding has been widely used in automotive, power, chemical, nuclear and aerospace industries. The quality of welded joints is closely related to the existing defects which are primarily determined by the welding process parameters. This paper proposes a defects optimization method that takes the formation mechanism of welding defects and weld geometric features into consideration. The analysis of welding defects formation mechanism aims to investigate the relationship between welding defects and process parameters, and weld features are considered to identify the optimal process parameters for the desired welded joints with minimum defects. The improved back-propagation neural network possessing good modeling for nonlinear problems is adopted to establish the mathematical model and the obtained model is solved by genetic algorithm. The proposed method is validated by macroweld profile, microstructure and microhardness in the confirmation tests. The results show that the proposed method is effective at reducing welding defects and obtaining high-quality joints for fiber laser keyhole welding in practical production.

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

    Jan Hackenberg

    2014-05-01

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

  11. [Research on the identification method of LTE condition in the laser-induced plasma].

    Fan, Juan-juan; Huang, Dan; Wang, Xin; Zhang, Lei; Ma, Wei-guang; Dong, Lei; Yin, Wang-bao; Jia, Suo-tang

    2014-12-01

    Because of the poor accuracy of the commonly used Boltzmann plot method and double-line method, the Boltzmann-Maxwell distribution combined with the Saha-Eggert formula is proposed to improve the measurement accuracy of the plasma temperature; the simple algorithm for determining the linewidth of the emission line was established according to the relationship between the area and the peak value of the Gaussian formula, and the plasma electron density was calculated through the Stark broadening of the spectral lines; the method for identifying the plasma local thermal equilibrium (LTE) condition was established based on the McWhirter criterion. The experimental results show that with the increase in laser energy, the plasma temperature and electron density increase linearly; when the laser energy changes within 127~510 mJ, the plasma electron density changes in the range of 1.30532X10(17)~1.87322X10(17) cm(-3), the plasma temperature changes in the range of 12586~12957 K, and all the plasma generated in this experiment meets the LTE condition threshold according to the McWhirter criterion. For element Al, there exist relatively few observable lines at the same ionization state in the spectral region of the spectrometer, thus it is unable to use the Boltzmann plane method to calculate temperature. One hundred sets of Al plasma spectra were used for temperature measurement by employing the Saha-Boltzmann method and the relative standard deviation (RSD) value is 0.4%, and compared with 1.3% of the double line method, the accuracy has been substantially increased. The methods proposed can be used for rapid plasma temperature and electron density calculation, the LTE condition identification, and are valuable in studies such as free calibration, spectral effectiveness analysis, spectral temperature correction, the best collection location determination, LTE condition distribution in plasma, and so on.

  12. The application of cost-effective lasers in coherent UDWDM-OFDM-PON aided by effective phase noise suppression methods.

    Liu, Yue; Yang, Chuanchuan; Yang, Feng; Li, Hongbin

    2014-03-24

    Digital coherent passive optical network (PON), especially the coherent orthogonal frequency division multiplexing PON (OFDM-PON), is a strong candidate for the 2nd-stage-next-generation PON (NG-PON2). As is known, OFDM is very sensitive to the laser phase noise which severely limits the application of the cost-effective distributed feedback (DFB) lasers and more energy-efficient vertical cavity surface emitting lasers (VCSEL) in the coherent OFDM-PON. The current long-reach coherent OFDM-PON experiments always choose the expensive external cavity laser (ECL) as the optical source for its narrow linewidth (usuallyOFDM-PON and study the possibility of the application of the DFB lasers and VCSEL in coherent OFDM-PON. A typical long-reach coherent ultra dense wavelength division multiplexing (UDWDM) OFDM-PON has been set up. The numerical results prove that the OBE method can stand severe phase noise of the lasers in this architecture and the DFB lasers as well as VCSEL can be used in coherent OFDM-PON. In this paper, we have also analyzed the performance of the RF-pilot-aided (RFP) phase noise suppression method in coherent OFDM-PON.

  13. Synthetic methods for beam to beam power balancing capability of large laser facilities

    Chen Guangyu; Zhang Xiaomin; Zhao Runchang; Zheng Wanguo; Yang Xiaoyu; You Yong; Wang Chengcheng; Shao Yunfei

    2011-01-01

    To account for output power balancing capability of large laser facilities, a synthetic method with beam to beam root-mean-square is presented. Firstly, a conversion process for the facilities from original data of beam powers to regular data is given. The regular data contribute to the normal distribution approximately, and then a corresponding simple method of root-mean-square for beam to beam power balancing capability is given.Secondly, based on theory of total control charts and cause-selecting control charts, control charts with root-mean-square are established which show short-term variety of power balancing capability of the facilities. Mean rate of failure occurrence is also defined and used to describe long-term trend of global balancing capabilities of the facilities. Finally, advantages of the intuitive and efficient diagnosis for synthetic methods are illustrated by analysis of experimental data. (authors)

  14. Laser-plasma interactions with a Fourier-Bessel particle-in-cell method

    Andriyash, Igor A., E-mail: igor.andriyash@gmail.com [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); LOA, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex (France); Lehe, Remi [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Lifschitz, Agustin [LOA, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex (France)

    2016-03-15

    A new spectral particle-in-cell (PIC) method for plasma modeling is presented and discussed. In the proposed scheme, the Fourier-Bessel transform is used to translate the Maxwell equations to the quasi-cylindrical spectral domain. In this domain, the equations are solved analytically in time, and the spatial derivatives are approximated with high accuracy. In contrast to the finite-difference time domain (FDTD) methods, that are used commonly in PIC, the developed method does not produce numerical dispersion and does not involve grid staggering for the electric and magnetic fields. These features are especially valuable in modeling the wakefield acceleration of particles in plasmas. The proposed algorithm is implemented in the code PLARES-PIC, and the test simulations of laser plasma interactions are compared to the ones done with the quasi-cylindrical FDTD PIC code CALDER-CIRC.

  15. A survey of some metallographic etching reagents for restoration of obliterated engraved marks on aluminium-silicon alloy surfaces.

    Uli, Norjaidi; Kuppuswamy, R; Amran, Mohd Firdaus Che

    2011-05-20

    A brief survey to assess the sensitivity and efficacy of some common etching reagents for revealing obliterated engraved marks on Al-Si alloy surfaces is presented. Experimental observations have recommended use of alternate swabbing of 10% NaOH and 10% HNO(3) on the obliterated surfaces for obtaining the desired results. The NaOH etchant responsible for bringing back the original marks resulted in the deposition of some dark coating that has masked the recovered marks. The coating had been well removed by dissolving it in HNO(3) containing 10-20% acid. However, the above etching procedure was not effective on aluminium (99% purity) and Al-Zn-Mg-Cu alloy surfaces. Also the two reagents (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH suggested earlier for high strength Al-Zn-Mg-Cu alloys [23] were quite ineffective on Al-Si alloys. Thus different aluminium alloys needed different etching treatments for successfully restoring the obliterated marks. Al-Si alloys used in casting find wide applications especially in the manufacture of engine blocks of motor vehicles. Hence, the results presented in this paper are of much relevance in serial number restoration problems involving this alloy. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  16. Colours in black and white: the depiction of lightness and brightness in achromatic engravings before the invention of photography.

    Zavagno, Daniele; Massironi, Manfredo

    2006-01-01

    What is it like to see the world in black and white? In the pioneer days of cinema, when movies displayed grey worlds, was it true that no 'colours' were actually seen? Did every object seen in those projections appear grey in the same way? The answer is obviously no--people in those glorious days were seeing a world full of light, shadows, and objects in which colours were expressed in terms of lightness. But the marvels of grey worlds have not always been so richly displayed. Before the invention of photography, the depiction of scenes in black-and-white had to face some technical and perceptual challenges. We have studied the technical and perceptual constraints that XV-XVIII century engravers had to face in order to translate actual colours into shades of grey. An indeterminacy principle is considered, according to which artists had to prefer the representation of some object or scene features over others (for example brightness over lightness). The reasons for this lay between the kind of grey scale technically available and the kind of information used in the construction of 3-D scenes. With the invention of photography, photomechanical reproductions, and new printing solutions, artists had at their disposal a continuous grey scale that greatly reduces the constraints of the indeterminacy principle.

  17. Measurement of the thermal diffusivity on ceramics and metals using the laser flash method

    Blumm, J.; Sauseng, B.

    2001-01-01

    Full Text: In the past few decades measurement of the thermophysical properties such as thermal expansion, specific heat, thermal diffusivity or thermal conductivity has become increasingly important for industrial applications. One example is the optimization of the heat transfer in industrial assemblies used for automotive or space applications. The thermal diffusivity and thermal conductivity of all components exposed to high and/or sub-ambient temperatures or large temperature gradients should be accurately known. Another well known example is the characterization of materials such as graphite used in nuclear reactors. Furthermore, analysis of solid and liquid metals is of paramount importance for the simulation of casting processes using finite element software programs. Thermal barrier coatings (zirconia) are used more and more often for high-temperature turbine blades. Reducing the thermal conductivity and the heat transfer through such coatings usually allows higher working temperatures and therefore higher efficiency of the gas turbine. These examples clearly demonstrate the need of instrumentation for the accurate measurement of the required thermophysical properties. The laser flash method has been developed to become one of the most commonly used techniques for the measurement of the thermal diffusivity of various kinds of solids and liquids. Easy sample preparation, small sample dimensions, fast measurement times and high accuracy are only some of the advantages of this non-destructive measurement technique. In addition, temperature dependent measurements can easily be realized. Since the development of the method by Parker et al. new routines for processing of the raw data have been established. Analytical mathematical descriptions were found to compensate for heat loss and finite pulse effects. Using modern personal computers and non-linear regression routines, mathematical models can be used to fit the raw data, yielding improved results for thermal

  18. A simple but precise method for quantitative measurement of the quality of the laser focus in a scanning optical microscope.

    Trägårdh, J; Macrae, K; Travis, C; Amor, R; Norris, G; Wilson, S H; Oppo, G-L; McConnell, G

    2015-07-01

    We report a method for characterizing the focussing laser beam exiting the objective in a laser scanning microscope. This method provides the size of the optical focus, the divergence of the beam, the ellipticity and the astigmatism. We use a microscopic-scale knife edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide, and a light-collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, a beam profile in the form of an error function can be obtained and by repeating this with the knife edge at different axial positions relative to the beam waist, the divergence and astigmatism of the postobjective laser beam can be obtained. The measured divergence can be used to quantify how much of the full numerical aperture of the lens is used in practice. We present data of the beam radius, beam divergence, ellipticity and astigmatism obtained with low (0.15, 0.7) and high (1.3) numerical aperture lenses and lasers commonly used in confocal and multiphoton laser scanning microscopy. Our knife-edge method has several advantages over alternative knife-edge methods used in microscopy including that the knife edge is easy to prepare, that the beam can be characterized also directly under a cover slip, as necessary to reduce spherical aberrations for objectives designed to be used with a cover slip, and it is suitable for use with commercial laser scanning microscopes where access to the laser beam can be limited. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  19. Analysis 'in vivo' of the employ of the Er:YAG laser and conventional method to remove carious tissue

    Ribeiro, Rafael Cardoso

    2002-01-01

    The aim of this study was to evaluate the removal of carious tissue employing the use of Er:YAG laser in comparison with the conventional burr rotary instrument. The wavelength of this laser is 2,64 μm and have a good absorption by the water and hydroxyapatite present in dental hard tissue. For this purpose were selected 24 molar teeth with occlusal carious, which were divided in random in two groups. For enamel, the laser energy used was in the interval from 250 mJ to 400 mJ, and the frequency range from 2 Hz to 4 Hz; for the dentine the energy laser range was from 150 mJ to 200 mJ and the laser frequency was in the range from 2 Hz to 6 Hz. For the evaluation of the results was used a questionaire to critical evaluation of the professional and another one to evaluation of the patient. The results have shown that the Er:YAG laser is able to remove carious enamel and dentin, without cause crunch or fracture and the irradiated surface was creasy. The patients reported greatest comfort when the cavity preparation was done with the Er:YAG laser than the conventional burr and all the patients treated reported prefer to future treatments the use of the Er:YAG laser. In conclusion, for the critical evaluation of the professional the treatment with the Er:YAG laser is a safe and effective method, and for the critical evaluation of the patient the treatment is one alternative more comfortable than the conventional method to remove caries. (author)

  20. Evaluation of positional plagiocephaly: Conventional anthropometric measurement versus laser scanning method.

    Nahles, Susanne; Klein, Martin; Yacoub, Anke; Neyer, Julia

    2018-01-01

    The incidence of plagiocephaly has increased in the 25 years since the "Back to Sleep" campaign in 1991 to prevent sudden infant death. Plagiocephaly is not considered to be a pathological condition. It is more of an esthetic impairment and could have potentially negative psychological or psychosocial consequences; therefore, treatment is recommended. The aim of this study is to compare conventional anthropometry and laser scanning - two different measurement methods - as diagnostic instruments for plagiocephaly. The present study also tests the measurement time of both methods and whether one method is easier on the patient than the other. A total of 44 children (21 girls, 23 boys) with a mean age of 8.8 months were involved in the present study. Of all patients, the following parameters were routinely evaluated using a standard protocol with the conventional anthropometric method and the scan method: head circumference, head length, head width, head diagonals, and distances ex-t. Furthermore, the time required to obtain measurements and the behavior of the children during measurement were documented. For statistical analysis, a t-test and a Wilcoxon test were used to analyze differences between the two methods. The results for head circumference showed a mean of 441.5 mm for the anthropometric measurements and 441.6 mm for the scan method, with no significant difference between the two methods. A significant difference was found regarding the head width, head length, diagonals, and distance ex-t. The measurement process using the scan method needed a mean of 579.6 s in contrast to the manual anthropometric method, which required a mean time of 180.5 s. In comparison with the conventional anthropometric method, measurements made with a 3D laser scanner yield inconsistent results. Moreover, the current state of technology of 3D cephalometry has no advantages compared with the conventional anthropometric method. Disadvantages worth mentioning appear to be the

  1. Multivariate methods for analysis of environmental reference materials using laser-induced breakdown spectroscopy

    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.

  2. Vertically aligned carbon nanotube growth by pulsed laser deposition and thermal chemical vapor deposition methods

    Sohn, Jung Inn; Nam, Chunghee; Lee, Seonghoon

    2002-01-01

    We have grown vertically aligned carbon nanotubes on the various substrates such as a planar p-type Si(1 0 0) wafer, porous Si wafer, SiO 2 , Si 3 N 4 , Al 2 O 3 , and Cr by thermal chemical vapor deposition (CVD) at 800 deg.C, using C 2 H 2 gas as a carbon source and Fe catalyst films deposited by a pulsed laser on the substrates. The Fe films were deposited for 5 min by pulsed laser deposition (PLD). The advantage of Fe deposition by PLD over other deposition methods lies in the superior adhesion of Fe to a Si substrate due to high kinetic energies of the generated Fe species. Scanning electron microscopy (SEM) images show that vertically well-aligned carbon nanotubes are grown on Fe nanoparticles formed from the thermal annealing of the Fe film deposited by PLD on the various substrates. Atomic force microscopy (AFM) images show that the Fe film annealed at 800 deg.C is broken to Fe nanoparticles of 10-50 nm in size. We show that the appropriate density of Fe nanoparticles formed from the thermal annealing of the film deposited by PLD is crucial in growing vertically aligned carbon nanotubes. Using a PLD and a lift-off method, we developed the selective growth of carbon nanotubes on a patterned Fe-coated Si substrate

  3. A Space-Frequency Data Compression Method for Spatially Dense Laser Doppler Vibrometer Measurements

    José Roberto de França Arruda

    1996-01-01

    Full Text Available When spatially dense mobility shapes are measured with scanning laser Doppler vibrometers, it is often impractical to use phase-separation modal parameter estimation methods due to the excessive number of highly coupled modes and to the prohibitive computational cost of processing huge amounts of data. To deal with this problem, a data compression method using Chebychev polynomial approximation in the frequency domain and two-dimensional discrete Fourier series approximation in the spatial domain, is proposed in this article. The proposed space-frequency regressive approach was implemented and verified using a numerical simulation of a free-free-free-free suspended rectangular aluminum plate. To make the simulation more realistic, the mobility shapes were synthesized by modal superposition using mode shapes obtained experimentally with a scanning laser Doppler vibrometer. A reduced and smoothed model, which takes advantage of the sinusoidal spatial pattern of structural mobility shapes and the polynomial frequency-domain pattern of the mobility shapes, is obtained. From the reduced model, smoothed curves with any desired frequency and spatial resolution can he produced whenever necessary. The procedure can he used either to generate nonmodal models or to compress the measured data prior to modal parameter extraction.

  4. Novel laser ellipsometry method for the KATRIN condensed {sup 83m}Kr source

    Zboril, Miroslav [Muenster Univ. (Germany). Inst. fuer Kernphysik; Collaboration: KATRIN-Collaboration

    2013-07-01

    One of the systematic effects in the neutrino mass experiment KATRIN are the fluctuations of the electric retarding potential which is experienced by the tritium β electrons on their path through the spectrometer. For the purpose of long-term monitoring of the energy scale stability several calibration electron sources will be utilised at KATRIN. One of them is the condensed {sup 83m}Kr source based on a frozen {sup 83m}Kr film on a HOPG backing at about 20 K. The isomeric state decays via a cascade of highly converted transitions, yielding conversion electron lines with energies ranging from 7.5 keV to 32.1 keV, useful for the energy calibration. The cleanliness of the HOPG backing is crucial as any adsorption of residual gas would shift the kinetic energy of the conversion electrons. The backing is cleaned via laser ablation and resistive heating. The cleanliness is checked via a novel method of laser ellipsometry where the polarisation analysis takes place directly in ultrahigh vacuum. The polarisation analysis is realised by an analyser and light detector at 90 K embedded in the cold baffle. This method allows to determine film thicknesses with a resolution of better than an atomic monolayer. As a byproduct it can be also used to determine the indices of refraction of condensed krypton and of the HOPG backing. The main features of the calibration source will be reviewed and the results of test measurements will be presented.

  5. Ann modeling of kerf transfer in Co2 laser cutting and optimization of cutting parameters using monte carlo method

    Miloš Madić

    2015-01-01

    Full Text Available In this paper, an attempt has been made to develop a mathematical model in order to study the relationship between laser cutting parameters such as laser power, cutting speed, assist gas pressure and focus position, and kerf taper angle obtained in CO2 laser cutting of AISI 304 stainless steel. To this aim, a single hidden layer artificial neural network (ANN trained with gradient descent with momentum algorithm was used. To obtain an experimental database for the ANN training, laser cutting experiment was planned as per Taguchi’s L27 orthogonal array with three levels for each of the cutting parameters. Statistically assessed as adequate, ANN model was then used to investigate the effect of the laser cutting parameters on the kerf taper angle by generating 2D and 3D plots. It was observed that the kerf taper angle was highly sensitive to the selected laser cutting parameters, as well as their interactions. In addition to modeling, by applying the Monte Carlo method on the developed kerf taper angle ANN model, the near optimal laser cutting parameter settings, which minimize kerf taper angle, were determined.

  6. Bacterial Adhesion on the Titanium and Stainless-Steel Surfaces Undergone Two Different Treatment Methods: Polishing and Ultrafast Laser Treatment

    Chik, N.; Zain, W. S. Wan Md; Mohamad, A. J.; Sidek, M. Z.; Ibrahim, W. H. Wan; Reif, A.; Rakebrandt, J. H.; Pfleging, W.; Liu, X.

    2018-05-01

    Bacterial adhesion has become a significant problem in many industries causing billions of dollars for its complicated removal treatment and maintenance. In this study, metal surfaces undergone treatment with ultrafast laser with varies power. The microstructure produced on its original surfaces were expected to prevent the adhesion of Escherichia coli (E. coli) ATCC 8739 and Staphylococcus aureus (S. aureus) ATCC 6838. The laser treatment was performed at 380 fs pulse duration, 515 µm central wavelength and a repetition rate of 200 kHz. Stainless steel AISI 316L was treated with an average laser power of 0.04 W (SS-0.04) and 0.11 W (SS-0.11), while Grade 5 titanium alloy was tested with high laser power 0.11 W (T-0.11). The adhesion was observed after 16 hours and the number of adhering bacteria was counted per cm2. The result achieved shows that, increasing the average laser power is leading to an enhanced S. aureus adhesion while E. coli adhesion is reduced which is due to the hydrophobicity interaction and difference in surface texture. Meanwhile, the laser treatment showed significant reduction of the bacterial adhesion on its surface compared to the polished surfaces. Thus, ultrafast laser texturing can be suggested as a promising method to reduce the bacterial adhesion, which reduced the adhesion of >80% for E. coli and >20% for S. aureus.

  7. Classical Measurement Methods and Laser Scanning Usage in Shaft Hoist Assembly Inventory

    Jaśkowski, Wojciech; Lipecki, Tomasz; Matwij, Wojciech; Jabłoński, Mateusz

    2018-03-01

    The shaft hoist assembly is the base of underground mining plant. Its efficiency and correct operation is subject to restrictive legal regulations and is controlled on a daily visual assessment by shaft crew and energomechanics. In addition, in the regular interval, the shaft hoist assembly is subject to a thorough inventory, which includes the determination of the geometrical relationships between the hoisting machine, the headframe and the shaft with its housing. Inventory measurements for shaft and headframe are used for years of conventional geodetic methods including mechanical or laser plumbing and tachymetric surveys. Additional precision levelling is also used for measuring shafts of hoisting machines and rope pulleys. Continuous modernization of measuring technology makes it possible to implement the further methods to the above mentioned purposes. The comparison of the accuracy and the economics of performing measurements based on many years of experience with comprehensive inventory of shaft hoist assembly using various research techniques was made and detailed in the article.

  8. Diagnostics of Susabi-nori (Porphyra Yezoensis) by Laser-Induced Fluorescence Method

    Okamoto, Tamotsu; Nakamura, Yuki; Takahashi, Kunio; Kaneko, Shohei; Shimada, Yuji

    Susabi-nori (Porphyra yezoensis) was diagnosed by means of laser-induced fluorescence (LIF) method. Fluorescence peaks located at approximately 580, 660, 685 and 720 nm were observed in the LIF spectra of Susabi-nori. In the spectrum of the sample infected with the red rot disease, the intensity of 580 nm peak was relatively high as compared with that of the control sample. On the other hand, the intensities of 580 nm and 660 nm peaks drastically decreased by the influence of the chytrid disease. Furthermore, the intensity of the 580 nm peak increased by dipping into fresh water. These results indicate that LIF spectra of Susabi-nori are affected by the diseases and the stress of fresh water and that the diseases and the stress of Susabi-nori can be diagnosed by the LIF method.

  9. Method for single-shot measurement of picosecond laser pulse-lengths without electronic time dispersion

    Kyrala, G.A.

    1987-01-01

    A two-source shear pattern recording is proposed as a method for single-shot measurement of the pulse shape from nearly monochromatic sources whose pulse lengths are shorter than their coherence times. The basis of this method relies on the assertion that if two identical electromagnetic pulses are recombined with a time delay greater than the sum of their pulse widths, the recordable spatial pattern has no fringes in it. At an arbitrary delay, translated into an actual spatial recording position, the recorded modulated intensity will sample the corresponding laser intensity at that delay time, but with a modulation due to the coherence function of the electromagnetic pulse. Two arrangements are proposed for recording the pattern. The principles, the design parameters, and the methodologies of these arrangements are presented. Resolutions of the configurations and their limitations are given as well

  10. Hydroxyapatite coatings on titanium dioxide thin films prepared by pulsed laser deposition method

    Suda, Yoshiaki; Kawasaki, Hiroharu; Ohshima, Tamiko; Nakashima, Shouta; Kawazoe, Syuichi; Toma, Tetsuya

    2006-01-01

    Hydroxyapatite (HAp) coated on titanium dioxide (TiO 2 ) thin films has been developed to supplement the defects of both TiO 2 and HAp. Thin films have been prepared by pulsed laser deposition (PLD) method using HAp and HAp(10%) + TiO 2 targets. X-ray diffraction (XRD) shows that there are many small peaks of Ca 1 0(PO 4 ) 6 (OH) 2 crystal, and no impurity other than HAp is detected in HAp films prepared using pure HAp target. The composition ratio of the film was analyzed by X-ray photoelectron spectroscopy (XPS). HAp coatings on TiO 2 thin films have been prepared using HAp(10%) + TiO 2 targets. XRD and XPS measurements suggest that crystalline HAp + TiO 2 thin films are obtained by the PLD method using HAp(10%) + TiO 2 target

  11. Method for spectrochemical analysis using time-resolved laser-induced breakdown. [Patent application

    Loree, T.R.; Radziemski, L.J.

    1982-01-26

    A method for real-time elemental analysis using laser-induced breakdown of the material under investigation and spectroscopic analysis of the light emitted from the plasma consequently formed is described. By delaying the observation of the emitted radiation, the unwanted background continuum and line spectra from excited ionic species can be rendered unimportant relative to the excited atomic line spectra, thereby producing sharp, well-defined characteristic identifying atomic spectral features. These features provide the indicia for detailed elemental analyses of substances. The method is quite general in that it applies to gases, surfaces, and particulates entrained in gases. It requires no electrodes and can excite atomic species like fluorine and chlorine which are difficult to observe by more conventional analytical procedures.

  12. A laser ablation ICP-MS based method for multiplexed immunoblot analysis

    de Bang, Thomas Christian; Petersen, Jørgen; Pedas, Pai Rosager

    2015-01-01

    developed a multiplexed antibody-based assay and analysed selected PSII subunits in barley (Hordeum vulgare L.). A selection of antibodies were labelled with specific lanthanides and immunoreacted with thylakoids exposed to Mn deficiency after western blotting. Subsequently, western blot membranes were...... analysed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), which allowed selective and relative quantitative analysis via the different lanthanides. The method was evaluated against established liquid chromatography electrospray ionization tandem mass spectrometry (LC...... by more than one technique. The developed method enables a higher number of proteins to be multiplexed in comparison to existing immunoassays. Furthermore, multiplexed protein analysis by LA-ICP-MS provides an analytical platform with high throughput appropriate for screening large collections of plants....

  13. Research on a wavefront aberration calculation method for a laser energy gradient attenuator

    Dong, Tingting; Han, Xu; Chen, Chi; Fu, Yuegang; Li, Ming

    2013-01-01

    When a laser energy gradient attenuator is working, there is an inhomogeneous temperature distribution in the whole of the glass because of the non-uniform light energy absorption. This will lead to optical performance reduction. An integrated opto-thermal–mechanical method is proposed to calculate the wavefront aberration for analysis of the thermal effect of the system. Non-sequential optical analysis is used for computing the absorbed energy distribution. The finite element analysis program solves the temperature distribution and the deformations of nodes on the surfaces. An interface routine is created to fit the surface shape and the index field, and extended Zernike polynomials are introduced to get a higher fitting precision. Finally, the parameters are imported to the CodeV optical design program automatically, and the user defined gradient index material is ray traced to obtain the wavefront aberration. The method can also be used in other optical systems for thermal effect analysis. (letter)

  14. Qualitative and quantitative determination of human biomarkers by laser photoacoustic spectroscopy methods

    Popa, C.; Bratu, A. M.; Matei, C.; Cernat, R.; Popescu, A.; Dumitras, D. C.

    2011-07-01

    The hypothesis that blood, urine and other body fluids and tissues can be sampled and analyzed to produce clinical information for disease diagnosis or therapy monitoring is the basis of modern clinical diagnosis and medical practice. The analysis of breath air has major advantages because it is a non-invasive method, represents minimal risk to personnel collecting the samples and can be often sampled. Breath air samples from the human subjects were collected using aluminized bags from QuinTron and analyzed using the laser photoacoustic spectroscopy (LPAS) technique. LPAS is used to detect traces of ethylene in breath air resulting from lipid peroxidation in lung epithelium following the radiotherapy and also traces of ammonia from patients subjected to hemodialysis for treatment of renal failure. In the case of patients affected by cancer and treated by external radiotherapy, all measurements were done at 10P(14) CO2 laser line, where the ethylene absorption coefficient has the largest value (30.4 cm-1 atm-1), whereas for patients affected by renal failure and treated by standard dialysis, all measurements were performed at 9R(30) CO2 laser line, where the ammonia absorption coefficient has the maximum value of 57 cm-1 atm-1. The levels of ethylene and ammonia in exhaled air, from patients with cancer and renal failure, respectively, were measured and compared with breath air contents from healthy humans. Human gas biomarkers were measured at sub-ppb (parts per billion) concentration sensitivities. It has been demonstrated that LPAS technique will play an important role in the future of exhaled breath air analysis. The key attributes of this technique are sensitivity, selectivity, fast and real time response, as well as its simplicity.

  15. Spectral fitting method for the solution of time-dependent Schroedinger equations: Applications to atoms in intense laser fields

    Qiao Haoxue; Cai Qingyu; Rao Jianguo; Li Baiwen

    2002-01-01

    A spectral fitting method for solving the time-dependent Schroedinger equation has been developed and applied to the atom in intense laser fields. This method allows us to obtain a highly accurate time-dependent wave function with a contribution from the high-order term of Δt. Moreover, the time-dependent wave function is determined on a small number of discrete mesh points, thus making calculations simple and accurate. This method is illustrated by computing wave functions and harmonic generation spectra of a model atom in laser fields

  16. Electron accelerator with a laser ignition for investigation of beam plasma by optical methods

    Kabanov, S.N.; Korolev, A.A.; Kul'beda, V.E.; Razumovskij, A.I.; Trukhin, V.A.

    1990-01-01

    Facility to conduct investigations into dense gas beam plasma is described. Facility comprises: electron accelerator (200-300 keV, 5kA, 20ns), OGM-40 ignition ruby laser LZhI-501 diagnostic laser (with 0.55-0.66 μm tunable wave length), Michelson interferometer and diagnostic equipment for optical measurements. Laser ignition of spark gap is introduced to strong synchronization (±10ns) of radiation pulse of diagnostic laser with beam current pulse

  17. Laser and Electron Beam Additive Manufacturing Methods of Fabricating Titanium Bone Implants

    Bartłomiej Wysocki

    2017-06-01

    Full Text Available Additive Manufacturing (AM methods are generally used to produce an early sample or near net-shape elements based on three-dimensional geometrical modules. To date, publications on AM of metal implants have mainly focused on knee and hip replacements or bone scaffolds for tissue engineering. The direct fabrication of metallic implants can be achieved by methods, such as Selective Laser Melting (SLM or Electron Beam Melting (EBM. This work compares the SLM and EBM methods used in the fabrication of titanium bone implants by analyzing the microstructure, mechanical properties and cytotoxicity. The SLM process was conducted in an environmental chamber using 0.4–0.6 vol % of oxygen to enhance the mechanical properties of a Ti-6Al-4V alloy. SLM processed material had high anisotropy of mechanical properties and superior UTS (1246–1421 MPa when compared to the EBM (972–976 MPa and the wrought material (933–942 MPa. The microstructure and phase composition depended on the used fabrication method. The AM methods caused the formation of long epitaxial grains of the prior β phase. The equilibrium phases (α + β and non-equilibrium α’ martensite was obtained after EBM and SLM, respectively. Although it was found that the heat transfer that occurs during the layer by layer generation of the component caused aluminum content deviations, neither methods generated any cytotoxic effects. Furthermore, in contrast to SLM, the EBM fabricated material met the ASTMF136 standard for surgical implant applications.

  18. A flexible calibration method for laser displacement sensors based on a stereo-target

    Zhang, Jie; Sun, Junhua; Liu, Zhen; Zhang, Guangjun

    2014-01-01

    Laser displacement sensors (LDSs) are widely used in online measurement owing to their characteristics of non-contact, high measurement speed, etc. However, existing calibration methods for LDSs based on the traditional triangulation measurement model are time-consuming and tedious to operate. In this paper, a calibration method for LDSs based on a vision measurement model of the LDS is presented. According to the constraint relationships of the model parameters, the calibration is implemented by freely moving a stereo-target at least twice in the field of view of the LDS. Both simulation analyses and real experiments were conducted. Experimental results demonstrate that the calibration method achieves an accuracy of 0.044 mm within the measurement range of about 150 mm. Compared to traditional calibration methods, the proposed method has no special limitation on the relative position of the LDS and the target. The linearity approximation of the measurement model in the calibration is not needed, and thus the measurement range is not limited in the linearity range. It is easy and quick to implement the calibration for the LDS. The method can be applied in wider fields. (paper)

  19. Method and apparatus for obtaining very high energy laser pulses: photon cyclotron

    Vali, V.; Krogstad, R.S.; Goldstein, R.

    1975-01-01

    Apparatus is arranged in selected embodiments of several combinations, each sometimes being referred to as a system, and each embodiment establishing a large enclosable chamber containing a laser energy reacting medium through which a laser beam is created. When laser energy pulses of such a beam are created, they are guided in a continuous path using reflectors in this chamber, and they receive supplemental energy units from multiple spaced laser pumps. Each laser pump is effective in respect to its own inverted population laser energy source, and each laser pump is triggered by an overall excitation control system. The laser beam is thereby supplemented to a higher level at each laser pump. Yet at all times the laser energy reacting medium remains at a level below super radiance. A working unit or working pulse of a laser beam is allowed to escape from each large enclosable chamber through an escape exit only when a preselected very high energy level is reached. The escape exit of this chamber may be designed to be destroyed by the exiting high level pulse energy of the laser beam. Also an escape exit may be opened upon the operation of a piezoelectric decoupler. (U.S.)

  20. Feasibility of Machine Learning Methods for Separating Wood and Leaf Points from Terrestrial Laser Scanning Data

    Wang, D.; Hollaus, M.; Pfeifer, N.

    2017-09-01

    Classification of wood and leaf components of trees is an essential prerequisite for deriving vital tree attributes, such as wood mass, leaf area index (LAI) and woody-to-total area. Laser scanning emerges to be a promising solution for such a request. Intensity based approaches are widely proposed, as different components of a tree can feature discriminatory optical properties at the operating wavelengths of a sensor system. For geometry based methods, machine learning algorithms are often used to separate wood and leaf points, by providing proper training samples. However, it remains unclear how the chosen machine learning classifier and features used would influence classification results. To this purpose, we compare four popular machine learning classifiers, namely Support Vector Machine (SVM), Na¨ıve Bayes (NB), Random Forest (RF), and Gaussian Mixture Model (GMM), for separating wood and leaf points from terrestrial laser scanning (TLS) data. Two trees, an Erytrophleum fordii and a Betula pendula (silver birch) are used to test the impacts from classifier, feature set, and training samples. Our results showed that RF is the best model in terms of accuracy, and local density related features are important. Experimental results confirmed the feasibility of machine learning algorithms for the reliable classification of wood and leaf points. It is also noted that our studies are based on isolated trees. Further tests should be performed on more tree species and data from more complex environments.

  1. FEASIBILITY OF MACHINE LEARNING METHODS FOR SEPARATING WOOD AND LEAF POINTS FROM TERRESTRIAL LASER SCANNING DATA

    D. Wang

    2017-09-01

    Full Text Available Classification of wood and leaf components of trees is an essential prerequisite for deriving vital tree attributes, such as wood mass, leaf area index (LAI and woody-to-total area. Laser scanning emerges to be a promising solution for such a request. Intensity based approaches are widely proposed, as different components of a tree can feature discriminatory optical properties at the operating wavelengths of a sensor system. For geometry based methods, machine learning algorithms are often used to separate wood and leaf points, by providing proper training samples. However, it remains unclear how the chosen machine learning classifier and features used would influence classification results. To this purpose, we compare four popular machine learning classifiers, namely Support Vector Machine (SVM, Na¨ıve Bayes (NB, Random Forest (RF, and Gaussian Mixture Model (GMM, for separating wood and leaf points from terrestrial laser scanning (TLS data. Two trees, an Erytrophleum fordii and a Betula pendula (silver birch are used to test the impacts from classifier, feature set, and training samples. Our results showed that RF is the best model in terms of accuracy, and local density related features are important. Experimental results confirmed the feasibility of machine learning algorithms for the reliable classification of wood and leaf points. It is also noted that our studies are based on isolated trees. Further tests should be performed on more tree species and data from more complex environments.

  2. Optimization of Selective Laser Melting by Evaluation Method of Multiple Quality Characteristics

    Khaimovich, A. I.; Stepanenko, I. S.; Smelov, V. G.

    2018-01-01

    Article describes the adoption of the Taguchi method in selective laser melting process of sector of combustion chamber by numerical and natural experiments for achieving minimum temperature deformation. The aim was to produce a quality part with minimum amount of numeric experiments. For the study, the following optimization parameters (independent factors) were chosen: the laser beam power and velocity; two factors for compensating the effect of the residual thermal stresses: the scale factor of the preliminary correction of the part geometry and the number of additional reinforcing elements. We used an orthogonal plan of 9 experiments with a factor variation at three levels (L9). As quality criterias, the values of distortions for 9 zones of the combustion chamber and the maximum strength of the material of the chamber were chosen. Since the quality parameters are multidirectional, a grey relational analysis was used to solve the optimization problem for multiple quality parameters. As a result, according to the parameters obtained, the combustion chamber segments of the gas turbine engine were manufactured.

  3. OPTIMASI PARAMETER MESIN LASER CUTTING TERHADAP KEKASARAN DAN LAJU PEMOTONGAN PADA SUS 316L MENGGUNAKAN TAGUCHI GREY RELATIONAL ANALYSIS METHOD

    Rakasita R

    2016-06-01

    Full Text Available Optimasi parameter adalah teknik yang digunakan pada proses manufaktur untuk menghasilkan produk terbaik. Penelitian ini bertujuan untuk mengoptimasi parameter CNC laser cutting, yaitu titik fokus sinar laser, tekanan gas cutting dan cutting speed untuk mengurangi variasi terhadap respon kekasaran dan laju pemotongan pada material SUS 316L. Masing-masing parameter memiliki 3 level dan pada penelitian ini menggunakan matriks orthogonal L9 (34. Metode ANOVA dan Taguchi digunakan untuk menganalisis data hasil percobaan. Optimasi kekasaran minimum permukaan dan laju pemotongan maksimum pada proses laser cutting dilakukan dengan menggunakan Grey relational analysis. Eksperimen konfirmasi digunakan untuk membuktikan hasil optimal yang telah didapatkan dari metode Taguchi Grey relational analysis. Hasil eksperimen menunjukkan bahwa Taguchi Grey relational analysis efektif digunakan untuk mengoptimasi parameter pemesinan pada laser cutting dengan multi respon.   Abstract Parameter optimization is used in manufacturing as an indicator to produce the best manufacturing product. This paper studies an optimization parameters of CNC laser cutting such as focus of laser beam, pressure cutting gases and cutting speed for reducing variation of surface roughness and cutting rate on material SUS 316L. Based on L9(34 orthogonal array parameters, it is analized using ANOVA based on Taguchi method. In order to optimaze the minimum surface roughness and maximum cutting rate in laser cutting process, it is used Grey relational analysis. The confirmation experiments used to validate the optimal results that has done by Taguchi method. The results show that the Taguchi Grey relational analysis is being effective to optimize the machining parameters for laser cutting process with two responses.

  4. Spectroscopy Methods and Applications of the Tor Vergata Laser-Plasma Facility Driven by GW-Level Laser System

    M. Francucci

    2011-01-01

    GW, tabletop, multistage Nd:YAG/Glass laser system, delivering infrared (IR pulses with nanosecond width and 1064 nm wavelength (TEM00 mode. Its applications are discussed providing: wide analysis of IR → soft X-ray conversion efficiency (1.3–1.55 keV; measures and modeling of line emission in soft X-ray spectra, such as those from zinc plasma near Ne-like Zn XXI and from barium plasma near Ni-like Ba XXIX. Particular attention is devoted to high-n dielectronic Rydberg satellites for finding a useful diagnostic tool for plasma conditions. Dependence of plasma spectra on laser parameters is shown. Finally, microradiography applications are presented for thin biological samples. Images permit to visualize specific structures and detect bioaccumulation sites due to contamination from pollutants.

  5. Study of a pressure measurement method using laser ionization for extremely-high vacuum

    Kokubun, Kiyohide

    1991-01-01

    A method of measuring pressures in the range of extremely-high vacuum (XHV) using the laser ionization has been studied. For this purpose, nonresonant multiphoton ionization of various kinds of gases has been studied, and highly-sensitive ion-detection systems and an extremely-high vacuum equipment were fabricated. These results are presented in detail. Two ion-detection systems were fabricated and tested: the one is based on the pulse-counting method, and the other utilizes the image-processing technique. The former is superior in detecting a few ions or less. The latter was processing technique. The former is superior in detecting a few ions or less. The latter was verified to able to count accurately the number of ions in the range of a few to several hundreds. To obtain the information on residual gases and test our pressure measurement system, an extremely-high vacuum system was fabricated in our own fashion, attained a pressure lower than 1 x 10 -10 Pa, measured with an extractor gauge. The outgassing rate of this vacuum vessel was measured to be 7.8 x 10 -11 Pa·m 3 /s·m 2 . The surface structures and the surface compositions of the raw material, the machined material, and the machined-and-outgased material were studied by SEM and AES. Besides, the pumping characteristics and the residual gases of the XHV system were investigated in detail at each pumping stage. On the course of these studies, the method of pressure measurement using the laser-ionization has been verified to be very effective for measuring pressures in XHV. (J.P.N.)

  6. Determination of weathering and conservation of sculptured stone by use of the laser method

    Aaberg, G.; Stijfhoorn, D.E.

    1996-09-01

    Weathering and deterioration of sculptured stone and masonry is a natural process which stars at the same moment the stone is quarried and exposed to exogenous conditions. This process of natural decay has, however, been accelerated due to the emission of different man-made pollutants, domestic and industrial, local and global. The ISOLASER project is based on the laser microprobe technique for determining the depth of natural and induced weathering and the effect of conservation measures of cultural objects of carbonaceous sandstone and marble/limestone. The purpose of the project is to determine the depth of weathering and depth of penetration of conservation agents in unweathered calcite-cemented stone and the weathering profile in linseed oil-treated stone after accelerated weathering cycles in a climatic chamber. The analytical results show that even after such a short period as five weeks of exposure the effect of SO 2 , NO 2 and elevated humidity on Gotland sandstone can be easily observed in a change of the δ 13 C values in the outermost 2 mm of the stone. Treating the sample with linseed oil has a preserving effect on the rock and hinders the deteriorating effect of SO 2 and NO 2 . The oil treatment even preserves the signature of previously incorporated organic carbon. Compilation of a questionnaire representing a broad field within natural sciences in cultural heritage research in Europe, shows an overwhelming positive approach to the project as such. The questioned researchers consider the laser method particularly useful as a complementary method in other investigations and states that the method can without doubt give new dimensions to the analysis of important cultural objects. 2 refs., 6 figs

  7. Investigation into the influence of laser energy input on selective laser melted thin-walled parts by response surface method

    Liu, Yang; Zhang, Jian; Pang, Zhicong; Wu, Weihui

    2018-04-01

    Selective laser melting (SLM) provides a feasible way for manufacturing of complex thin-walled parts directly, however, the energy input during SLM process, namely derived from the laser power, scanning speed, layer thickness and scanning space, etc. has great influence on the thin wall's qualities. The aim of this work is to relate the thin wall's parameters (responses), namely track width, surface roughness and hardness to the process parameters considered in this research (laser power, scanning speed and layer thickness) and to find out the optimal manufacturing conditions. Design of experiment (DoE) was used by implementing composite central design to achieve better manufacturing qualities. Mathematical models derived from the statistical analysis were used to establish the relationships between the process parameters and the responses. Also, the effects of process parameters on each response were determined. Then, a numerical optimization was performed to find out the optimal process set at which the quality features are at their desired values. Based on this study, the relationship between process parameters and SLMed thin-walled structure was revealed and thus, the corresponding optimal process parameters can be used to manufactured thin-walled parts with high quality.

  8. Electromagnetic numerical characterization of the laser-induced liquid crystal lens by finite-difference time domain method

    Morisaki, T.; Ono, H.

    2005-01-01

    A laser-induced liquid-crystal lens is formed by large optical non-linearity and anisotropic complex refractive indices in guest-host liquid crystals. We obtained light wave propagation characteristics of the laser-induced LC lens. Three analytical methods were used to obtain light wave propagation characteristics. Analysis by 3-dimensional heat conduction was applied to determine the refractive index in the liquid-crystal layer. Another method used was to determine light wave propagation characteristics in the laser-induced lens by means of the finite-difference tune domain (FDTD) method and diffraction theory. In this study, we draw a parallel between the experimental results and FDTD. Copyright (2003) AD-TECH - International Foundation for the Advancement of Technology Ltd

  9. A study on new method of noninvasive esophageal venous pressure measurement based on the airflow and laser detection technology.

    Hu, Chenghuan; Huang, Feizhou; Zhang, Rui; Zhu, Shaihong; Nie, Wanpin; Liu, Xunyang; Liu, Yinglong; Li, Peng

    2015-01-01

    Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed pump and a laser emitting apparatus could generate optical signals which can be captured by image acquisition and analysis system program. A synchronization system simultaneous measured the changes of air pressure and the deformation of the vein wall to capture the vascular deformation while simultaneously record the current pressure value. The results of this study indicated that the pressure values tested by the new method have good correlation with the actual pressure value in animal experiments. The new method of noninvasive pressure measurement based on the airflow and laser detection technology is accurate, feasible, repeatable and has a good application prospects.

  10. [Comparative adaptation of crowns of selective laser melting and wax-lost-casting method].

    Li, Guo-qiang; Shen, Qing-yi; Gao, Jian-hua; Wu, Xue-ying; Chen, Li; Dai, Wen-an

    2012-07-01

    To investigate the marginal adaptation of crowns fabricated by selective laser melting (SLM) and wax-lost-casting method, so as to provide an experimental basis for clinic. Co-Cr alloy full crown were fabricated by SLM and wax-lost-casting for 24 samples in each group. All crowns were cemented with zinc phosphate cement and cut along longitudinal axis by line cutting machine. The gap between crown tissue surface and die was measured by 6-point measuring method with scanning electron microscope (SEM). The marginal adaptation of crowns fabricated by SLM and wax-lost-casting were compared statistically. The gap between SLM crowns were (36.51 ± 2.94), (49.36 ± 3.31), (56.48 ± 3.35), (42.20 ± 3.60) µm, and wax-lost-casting crowns were (68.86 ± 5.41), (58.86 ± 6.10), (70.62 ± 5.79), (69.90 ± 6.00) µm. There were significant difference between two groups (P casting method and SLM method provide acceptable marginal adaptation in clinic, and the marginal adaptation of SLM is better than that of wax-lost-casting method.

  11. A Novel and Effective Multivariate Method for Compositional Analysis using Laser Induced Breakdown Spectroscopy

    Wang, W; Qi, H; Ayhan, B; Kwan, C; Vance, S

    2014-01-01

    Compositional analysis is important to interrogate spectral samples for direct analysis of materials in agriculture, environment and archaeology, etc. In this paper, multi-variate analysis (MVA) techniques are coupled with laser induced breakdown spectroscopy (LIBS) to estimate quantitative elemental compositions and determine the type of the sample. In particular, we present a new multivariate analysis method for composition analysis, referred to as s pectral unmixing . The LIBS spectrum of a testing sample is considered as a linear mixture with more than one constituent signatures that correspond to various chemical elements. The signature library is derived from regression analysis using training samples or is manually set up with the information from an elemental LIBS spectral database. A calibration step is used to make all the signatures in library to be homogeneous with the testing sample so as to avoid inhomogeneous signatures that might be caused by different sampling conditions. To demonstrate the feasibility of the proposed method, we compare it with the traditional partial least squares (PLS) method and the univariate method using a standard soil data set with elemental concentration measured a priori. The experimental results show that the proposed method holds great potential for reliable and effective elemental concentration estimation

  12. Automatic variable selection method and a comparison for quantitative analysis in laser-induced breakdown spectroscopy

    Duan, Fajie; Fu, Xiao; Jiang, Jiajia; Huang, Tingting; Ma, Ling; Zhang, Cong

    2018-05-01

    In this work, an automatic variable selection method for quantitative analysis of soil samples using laser-induced breakdown spectroscopy (LIBS) is proposed, which is based on full spectrum correction (FSC) and modified iterative predictor weighting-partial least squares (mIPW-PLS). The method features automatic selection without artificial processes. To illustrate the feasibility and effectiveness of the method, a comparison with genetic algorithm (GA) and successive projections algorithm (SPA) for different elements (copper, barium and chromium) detection in soil was implemented. The experimental results showed that all the three methods could accomplish variable selection effectively, among which FSC-mIPW-PLS required significantly shorter computation time (12 s approximately for 40,000 initial variables) than the others. Moreover, improved quantification models were got with variable selection approaches. The root mean square errors of prediction (RMSEP) of models utilizing the new method were 27.47 (copper), 37.15 (barium) and 39.70 (chromium) mg/kg, which showed comparable prediction effect with GA and SPA.

  13. Spectrophotometric analysis of the effectiveness of a novel in-office laser-assisted tooth bleaching method using Er,Cr:YSGG laser.

    Dionysopoulos, Dimitrios; Strakas, Dimitrios; Tolidis, Kosmas; Tsitrou, Effrosyni; Koumpia, Effimia; Koliniotou-Koumpia, Eugenia

    2017-11-01

    The purpose of this in vitro study was to compare the effectiveness of a novel Er,Cr:YSGG laser-assisted in-office tooth bleaching method with a conventional method by spectrophotometric analysis of the tooth color change. Furthermore, the influence of the application time of the bleaching gel on the effectiveness of the methods and the maintenance of the results 7 days and 1 month after the treatments were also evaluated. Twenty-four bovine incisors were stained and randomly distributed into four groups. Group 1 specimens received an in-office bleaching treatment with 35% H 2 O 2 for 2 × 15 min. Group 2 specimens received the same treatment but with extended application time (2 × 20 min). In Group 3, the same in-office bleaching procedure (2 × 15 min) was carried out as that in Group 1, using Er,Cr:YSGG laser irradiation for 2 × 15 s on each specimen to catalyze the reaction of H 2 O 2 breakdown. Group 4 specimens received the same bleaching treatment as Group 3 but with extended application time (2 × 20 min). Er,Cr:YSGG laser-assisted tooth bleaching treatment is more effective than the conventional treatment regarding color change of the teeth. Application time of the bleaching agent may influence the effectiveness of the methods. The color change of the tested treatments decreases after 7 days and 1 month. The clinical relevance of this study is that this novel laser-assisted bleaching treatment may be more advantageous in color change and application time compared to the conventional bleaching treatment.

  14. A method for the measurement of in line pistachio aflatoxin concentration based on the laser induced fluorescence spectroscopy

    Paghaleh, Soodeh Jamali; Askari, Hassan Ranjbar; Marashi, Seyed Mohammad Bagher; Rahimi, Mojtaba; Bahrampour, Ali Reza

    2015-01-01

    Contamination of pistachio nuts with aflatoxin is one of the most significant issues related to pistachio health and expert. A fast pistachio aflatoxin concentration measurement method based on the laser induced fluorescence spectroscopy (LIFS) is proposed. The proposed method from theoretical and experimental points of view is analyzed. In our experiments XeCl Excimer laser is employed as an Ultra Violet (UV) source (λ=308 nm) and a UV–visible (UV–vis) spectrometer is used for fluorescent emission detection. Our setup is employed to measure the concentration of different type of Aflatoxins in pistachio nuts. Measurements results obtained by the LIFS method are compared with those are measured by the standard HPLC method. Aflatoxins concentrations are in good agreement with those are obtained by the HPLC method. The proposed laser induced fluorescence spectroscopy can be used as an in line aflatoxins concentrations measurement instrument for industrial applications. - Highlights: • XeCl Excimer laser is employed as an UV source for measurement of AFs in pistachio nuts. • Results are compared with those are measured by the standard HPLC method. • LIFS is an online AFs concentration measurement method for industrial applications

  15. Development of Ultrafast Laser Flash Methods for Measuring Thermophysical Properties of Thin Films and Boundary Thermal Resistances

    Baba, Tetsuya; Taketoshi, Naoyuki; Yagi, Takashi

    2011-11-01

    Reliable thermophysical property values of thin films are important to develop advanced industrial technologies such as highly integrated electronic devices, phase-change memories, magneto-optical disks, light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), semiconductor lasers (LDs), flat-panel displays, and power electronic devices. In order to meet these requirements, the National Metrology Institute of Japan of the National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) has developed ultrafast laser flash methods heated by picosecond pulse or nanosecond pulse with the same geometrical configuration as the laser flash method, which is the standard method to measure the thermal diffusivity of bulk materials. Since these pulsed light heating methods induce one-dimensional heat diffusion across a well-defined length of the specimen thickness, the absolute value of thermal diffusivity across thin films can be measured reliably. Using these ultrafast laser flash methods, the thermal diffusivity of each layer of multilayered thin films and the boundary thermal resistance between the layers can be determined from the observed transient temperature curves based on the response function method. The thermophysical properties of various thin films important for modern industries such as the transparent conductive films used for flat-panel displays, hard coating films, and multilayered films of next-generation phase-change optical disks have been measured by these methods.

  16. Fundamental study of microelectronic chip response under laser ultrasonic-interferometric inspection using C-scan method

    Yang, Lei; Gong, Jie; Ume, I. Charles

    2014-02-01

    In modern surface mount packaging technologies, such as flip chips, chip scale packages, and ball grid arrays(BGA), chips are attached to the substrates/printed wiring board (PWB) using solder bump interconnections. The quality of solder bumps between the chips and the substrate/board is difficult to inspect. Laser ultrasonic-interferometric technique was proved to be a promising approach for solder bump inspection because of its noncontact and nondestructive characteristics. Different indicators extracted from received signals have been used to predict the potential defects, such as correlation coefficient, error ratio, frequency shifting, etc. However, the fundamental understanding of the chip behavior under laser ultrasonic inspection is still missing. Specifically, it is not sure whether the laser interferometer detected out-of-plane displacements were due to wave propagation or structural vibration when the chip was excited by pulsed laser. Plus, it is found that the received signals are chip dependent. Both challenges impede the interpretation of acquired signals. In this paper, a C-scan method was proposed to study the underlying phenomenon during laser ultrasonic inspection. The full chip was inspected. The response of the chip under laser excitation was visualized in a movie resulted from acquired signals. Specifically, a BGA chip was investigated to demonstrate the effectiveness of this method. By characterizing signals using discrete wavelet transform(DWT), both ultrasonic wave propagation and vibration were observed. Separation of them was successfully achieved using ideal band-pass filter and visualized in resultant movies, too. The observed ultrasonic waves were characterized and their respective speeds were measured by applying 2-D FFT. The C-scan method, combined with different digital signal processing techniques, was proved to be an very effective methodology to learn the behavior of chips under laser excitation. This general procedure can be

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

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

    2002-01-01

    energy as well as electron energy. We have estimated the time constant for energy transfer between the electrons and the ions. The scaling of these processes is given by a single parameter determined by the Debye length obtained from the electron density in the plasma outside the surface. (C) 2002......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...... et al. It is assumed that the particle ablation from a surface with a fixed temperature takes place as a pulse, i.e. within a finite period of time. A number of characteristic quantities for the plasma plume are compared with similar data for expansion of neutrals as well as fluid models: Density...

  18. Determination of uranium in sea and ocean waters by a luminescence method with laser excitation

    Preobrazhenskaya, E.B.; Gvgel, E.S.; Stepanov, A.V.

    1986-01-01

    This paper shows that it is possible to determine uranium insea and ocean waters by a luminescence method with laser excitation. Ocean waters with a low content of luminescent ingredients are analyzed directly by freezing at 77 K to eliminate the quenching effect of the chloride ion. The more polluted waters of inland seas are preferably analyzed at T = 293 K in 1 M H 3 PO 4 after the removal of chloride ions by distillation from a sample containing HNO 3 . The background effect is removed by time selection of the luminescent emission of the uranyl ion. Uranium contents were determined for water from the northwest Atlantic and the North and Baltic Seas

  19. SINGLE TREE DETECTION FROM AIRBORNE LASER SCANNING DATA USING A MARKED POINT PROCESS BASED METHOD

    J. Zhang

    2013-05-01

    Full Text Available Tree detection and reconstruction is of great interest in large-scale city modelling. In this paper, we present a marked point process model to detect single trees from airborne laser scanning (ALS data. We consider single trees in ALS recovered canopy height model (CHM as a realization of point process of circles. Unlike traditional marked point process, we sample the model in a constraint configuration space by making use of image process techniques. A Gibbs energy is defined on the model, containing a data term which judge the fitness of the model with respect to the data, and prior term which incorporate the prior knowledge of object layouts. We search the optimal configuration through a steepest gradient descent algorithm. The presented hybrid framework was test on three forest plots and experiments show the effectiveness of the proposed method.

  20. Apparatus and method for pulsed laser deposition of materials on wires and pipes

    Fernandez, Felix E.

    2003-01-01

    Methods and apparatuses are disclosed which allow uniform coatings to be applied by pulsed laser deposition (PLD) on inner and outer surfaces of cylindrical objects, such as rods, pipes, tubes, and wires. The use of PLD makes this technique particularly suitable for complex multicomponent materials, such as superconducting ceramics. Rigid objects of any length, i.e., pipes up to a few meters, and with diameters from less than 1 centimeter to over 10 centimeters can be coated using this technique. Further, deposition is effected simultaneously onto an annular region of the pipe wall. This particular arrangement simplifies the apparatus, reduces film uniformity control difficulties, and can result in faster operation cycles. In addition, flexible wires of any length can be continuously coated using the disclosed invention.

  1. Diode-laser-pump module with integrated signal ports for pumping amplifying fibers and method

    Savage-Leuchs,; Matthias, P [Woodinville, WA

    2009-05-26

    Apparatus and method for collimating pump light of a first wavelength from laser diode(s) into a collimated beam within an enclosure having first and second optical ports, directing pump light from the collimated beam to the first port; and directing signal light inside the enclosure between the first and second port. The signal and pump wavelengths are different. The enclosure provides a pump block having a first port that emits pump light to a gain fiber outside the enclosure and that also passes signal light either into or out of the enclosure, and another port that passes signal light either out of or into the enclosure. Some embodiments use a dichroic mirror to direct pump light to the first port and direct signal light between the first and second ports. Some embodiments include a wavelength-conversion device to change the wavelength of at least some of the signal light.

  2. Alkali resistant optical coatings for alkali lasers and methods of production thereof

    Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

    2014-11-18

    In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

  3. Electromagnetic particle-in-cell (PIC) method for modeling the formation of metal surface structures induced by femtosecond laser radiation

    Djouder, M. [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri de Tizi-ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria); Lamrous, O., E-mail: omarlamrous@mail.ummto.dz [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri de Tizi-ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria); Mitiche, M.D. [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri de Tizi-ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria); Itina, T.E. [Laboratoire Hubert Curien, UMR CNRS 5516/Université Jean Monnet, 18 rue de Professeur Benoît Lauras, 42000 Saint-Etienne (France); Zemirli, M. [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri de Tizi-ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria)

    2013-09-01

    The particle in cell (PIC) method coupled to the finite-difference time-domain (FDTD) method is used to model the formation of laser induced periodic surface structures (LIPSS) at the early stage of femtosecond laser irradiation of smooth metal surface. The theoretical results were analyzed and compared with experimental data taken from the literature. It was shown that the optical properties of the target are not homogeneous and the ejection of electrons is such that ripples in the electron density were obtained. The Coulomb explosion mechanism was proposed to explain the ripples formation under the considered conditions.

  4. Electromagnetic particle-in-cell (PIC) method for modeling the formation of metal surface structures induced by femtosecond laser radiation

    Djouder, M.; Lamrous, O.; Mitiche, M.D.; Itina, T.E.; Zemirli, M.

    2013-01-01

    The particle in cell (PIC) method coupled to the finite-difference time-domain (FDTD) method is used to model the formation of laser induced periodic surface structures (LIPSS) at the early stage of femtosecond laser irradiation of smooth metal surface. The theoretical results were analyzed and compared with experimental data taken from the literature. It was shown that the optical properties of the target are not homogeneous and the ejection of electrons is such that ripples in the electron density were obtained. The Coulomb explosion mechanism was proposed to explain the ripples formation under the considered conditions.

  5. A method of measuring micro-impulse with torsion pendulum based on multi-beam laser heterodyne

    Li, Yan-Chao; Wang, Chun-Hui

    2012-02-01

    In this paper, we propose a novel method of multi-beam laser heterodyne measurement for micro-impulse. The measurement of the micro-impulse, which is converted into the measurement of the small tuning angle of the torsion pendulum, is realized by considering the interaction between pulse laser and working medium. Based on Doppler effect and heterodyne technology, the information regarding the small tuning angle is loaded to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, thereby obtaining many values of the small tuning angle after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, the small tuning angle can be obtained accurately and the value of the micro-impulse can eventually be calculated. Using Polyvinylchlorid+2%C as a working medium, this novel method is used to simulate the value of the micro-impulse by MATLAB which is generated by considering the interaction between the pulse laser and the working medium, the obtained result shows that the relative error of this method is just 0.5%.

  6. A method of measuring micro-impulse with torsion pendulum based on multi-beam laser heterodyne

    Li Yan-Chao; Wang Chun-Hui

    2012-01-01

    In this paper, we propose a novel method of multi-beam laser heterodyne measurement for micro-impulse. The measurement of the micro-impulse, which is converted into the measurement of the small tuning angle of the torsion pendulum, is realized by considering the interaction between pulse laser and working medium. Based on Doppler effect and heterodyne technology, the information regarding the small tuning angle is loaded to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, thereby obtaining many values of the small tuning angle after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, the small tuning angle can be obtained accurately and the value of the micro-impulse can eventually be calculated. Using Polyvinylchlorid+2%C as a working medium, this novel method is used to simulate the value of the micro-impulse by MATLAB which is generated by considering the interaction between the pulse laser and the working medium, the obtained result shows that the relative error of this method is just 0.5%. (general)

  7. New phase method of measuring particle size with laser Doppler radar

    Zemlianskii, Vladimir M.

    1996-06-01

    A vast field of non-contact metrology, vibrometry, dynamics and microdynamics problems solved on the basis of laser Doppler method resulted in the development of great variety of laser Doppler radar (LDR). In coherent LDR few beams with various polarization are generally adopted, that are directed at the zone of measurement, through which the probing air stream moves. Studies of various coherent LDR demonstrated that polarization-phase effects of scattering can in some cases considerably effect on the signal-to-noise ratio of the Doppler signal. On the other side using phase effects can simultaneous measurement of size and velocity of spherical particles. New possibilities for improving the accuracy of measuring spherical particles' sizes come to light when application is made in coherent LDR of two waves- probing and one out of the types of symmetrical reception of scattered radiation, during which phase-conjugate signals are formed. The theoretical analysis on the basis of the scattering theory showed, that in symmetrical reception of scattered radiation with respect to the planes OXZ and OYZ output signal of the photoreceiver contains two high- frequency signal components, which in relation to parameters of the probing and size, can either be in phase or antiphase. Results of numerical modeling are presented: amplitude of high frequency signal, coefficient of phase and polarization matching of mixed waves, the depths of photocurrent modulation and also signal's phase in relation to the angle between the probing beams. Phase method of determining particle's sizes based on the use of two wavelengths probing and symmetrical reception of scattered radiation in which conditions for the formation of phase conjugated high-frequency signals are satisfied is presented.

  8. Diagnosis of human malignancies using laser-induced breakdown spectroscopy in combination with chemometric methods

    Chen, Xue; Li, Xiaohui; Yu, Xin; Chen, Deying; Liu, Aichun

    2018-01-01

    Diagnosis of malignancies is a challenging clinical issue. In this work, we present quick and robust diagnosis and discrimination of lymphoma and multiple myeloma (MM) using laser-induced breakdown spectroscopy (LIBS) conducted on human serum samples, in combination with chemometric methods. The serum samples collected from lymphoma and MM cancer patients and healthy controls were deposited on filter papers and ablated with a pulsed 1064 nm Nd:YAG laser. 24 atomic lines of Ca, Na, K, H, O, and N were selected for malignancy diagnosis. Principal component analysis (PCA), linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), and k nearest neighbors (kNN) classification were applied to build the malignancy diagnosis and discrimination models. The performances of the models were evaluated using 10-fold cross validation. The discrimination accuracy, confusion matrix and receiver operating characteristic (ROC) curves were obtained. The values of area under the ROC curve (AUC), sensitivity and specificity at the cut-points were determined. The kNN model exhibits the best performances with overall discrimination accuracy of 96.0%. Distinct discrimination between malignancies and healthy controls has been achieved with AUC, sensitivity and specificity for healthy controls all approaching 1. For lymphoma, the best discrimination performance values are AUC = 0.990, sensitivity = 0.970 and specificity = 0.956. For MM, the corresponding values are AUC = 0.986, sensitivity = 0.892 and specificity = 0.994. The results show that the serum-LIBS technique can serve as a quick, less invasive and robust method for diagnosis and discrimination of human malignancies.

  9. Histological staining methods preparatory to laser capture microdissection significantly affect the integrity of the cellular RNA

    Li Ming-Chung

    2006-04-01

    Full Text Available Abstract Background Gene expression profiling by microarray analysis of cells enriched by laser capture microdissection (LCM faces several technical challenges. Frozen sections yield higher quality RNA than paraffin-imbedded sections, but even with frozen sections, the staining methods used for histological identification of cells of interest could still damage the mRNA in the cells. To study the contribution of staining methods to degradation of results from gene expression profiling of LCM samples, we subjected pellets of the mouse plasma cell tumor cell line TEPC 1165 to direct RNA extraction and to parallel frozen sectioning for LCM and subsequent RNA extraction. We used microarray hybridization analysis to compare gene expression profiles of RNA from cell pellets with gene expression profiles of RNA from frozen sections that had been stained with hematoxylin and eosin (H&E, Nissl Stain (NS, and for immunofluorescence (IF as well as with the plasma cell-revealing methyl green pyronin (MGP stain. All RNAs were amplified with two rounds of T7-based in vitro transcription and analyzed by two-color expression analysis on 10-K cDNA microarrays. Results The MGP-stained samples showed the least introduction of mRNA loss, followed by H&E and immunofluorescence. Nissl staining was significantly more detrimental to gene expression profiles, presumably owing to an aqueous step in which RNA may have been damaged by endogenous or exogenous RNAases. Conclusion RNA damage can occur during the staining steps preparatory to laser capture microdissection, with the consequence of loss of representation of certain genes in microarray hybridization analysis. Inclusion of RNAase inhibitor in aqueous staining solutions appears to be important in protecting RNA from loss of gene transcripts.

  10. Histological staining methods preparatory to laser capture microdissection significantly affect the integrity of the cellular RNA.

    Wang, Hongyang; Owens, James D; Shih, Joanna H; Li, Ming-Chung; Bonner, Robert F; Mushinski, J Frederic

    2006-04-27

    Gene expression profiling by microarray analysis of cells enriched by laser capture microdissection (LCM) faces several technical challenges. Frozen sections yield higher quality RNA than paraffin-imbedded sections, but even with frozen sections, the staining methods used for histological identification of cells of interest could still damage the mRNA in the cells. To study the contribution of staining methods to degradation of results from gene expression profiling of LCM samples, we subjected pellets of the mouse plasma cell tumor cell line TEPC 1165 to direct RNA extraction and to parallel frozen sectioning for LCM and subsequent RNA extraction. We used microarray hybridization analysis to compare gene expression profiles of RNA from cell pellets with gene expression profiles of RNA from frozen sections that had been stained with hematoxylin and eosin (H&E), Nissl Stain (NS), and for immunofluorescence (IF) as well as with the plasma cell-revealing methyl green pyronin (MGP) stain. All RNAs were amplified with two rounds of T7-based in vitro transcription and analyzed by two-color expression analysis on 10-K cDNA microarrays. The MGP-stained samples showed the least introduction of mRNA loss, followed by H&E and immunofluorescence. Nissl staining was significantly more detrimental to gene expression profiles, presumably owing to an aqueous step in which RNA may have been damaged by endogenous or exogenous RNAases. RNA damage can occur during the staining steps preparatory to laser capture microdissection, with the consequence of loss of representation of certain genes in microarray hybridization analysis. Inclusion of RNAase inhibitor in aqueous staining solutions appears to be important in protecting RNA from loss of gene transcripts.

  11. Experimental Study of Laser Cladding Methods on Water Erosion Resistance to Low Pressure Blades Materials of Steam Turbine

    Di Zhang

    2014-01-01

    Full Text Available An experimental apparatus was built to study the effects of liquid-solid impact on laser cladding processing specimens of 17-4PH stainless steel material in the present investigation. Then the result of specimens without laser surface process was compared. The impact effect on the specimens was observed using the three-dimensional digital microscope. The depth of laser cladding and substrate material caused by liquid droplet impact was studied in detail and measured. The accuracy and reliability of the experimental system and computing methods were also verified. The depth of the impact area of laser cladding specimens was distributed in the range of 0.5–1.5 μm while the 17-4PH group was distributed in the range of 2.5–3.5 μm. In contrast with specimens without laser surface processing, the material processed by laser cladding has significantly higher resistance to water erosion.

  12. Uranium dioxide thermal characterization by the flash laser method from 23 Celsius to 175 Celsius

    Faeda, K.C.M.; Lameiras, F.S.; Carneiro, L.S.S.; Camarano, D.M.; Ferreira, R.A.N.

    2010-01-01

    The Laser Flash Method has become one of the most common techniques for measuring thermal diffusivity and conductivity in solids and liquids. This method is recognized by INMETRO as standard to be used in Brazil for measuring thermophysical properties of materials, such as metals, carbon composites, ceramics, and also nuclear materials. This article describes the experimental bench of the LMPT-Laboratorio de Medicao de Propriedades Termofisicas de Combustiveis Nucleares e Materiais of the CDTN-Centro de Desenvolvimento da Tecnologia Nuclear, (LMPT), as well as the mathematical model developed based on this method. The obtained results for the thermal diffusivity and for the thermal conductivity of uranium dioxide (U0 2 ) pellets in the temperature range from 25 deg to 175 deg C, are discussed and compared with the literature data. The estimative of the input quantities uncertainty of the mathematical model was determined according to ISO - BIPM-Guide to the Expression of Uncertainty in Measurement and the Monte Carlo Method was used to estimate of the output quantities uncertainty (thermal diffusivity and thermal conductivity). Additionally the results of the x-rays of these pellets are presented. (author)

  13. A method of reducing background fluctuation in tunable diode laser absorption spectroscopy

    Yang, Rendi; Dong, Xiaozhou; Bi, Yunfeng; Lv, Tieliang

    2018-03-01

    Optical interference fringe is the main factor that leads to background fluctuation in gas concentration detection based on tunable diode laser absorption spectroscopy. The interference fringes are generated by multiple reflections or scatterings upon optical surfaces in optical path and make the background signal present an approximated sinusoidal oscillation. To reduce the fluctuation of the background, a method that combines dual tone modulation (DTM) with vibration reflector (VR) is proposed in this paper. The combination of DTM and VR can make the unwanted periodic interference fringes to be averaged out and the effectiveness of the method in reducing background fluctuation has been verified by simulation and real experiments in this paper. In the detection system based on the proposed method, the standard deviation (STD) value of the background signal is decreased to 0.0924 parts per million (ppm), which is reduced by a factor of 16 compared with that of wavelength modulation spectroscopy. The STD value of 0.0924 ppm corresponds to the absorption of 4 . 328 × 10-6Hz - 1 / 2 (with effective optical path length of 4 m and integral time of 0.1 s). Moreover, the proposed method presents a better stable performance in reducing background fluctuation in long time experiments.

  14. SYNTHESIS OF 2,6-DIAMINOPYRIDINE-4-NITROPHENOL (2,6DAP4N COCRYSTAL NANOPARTICLES BY LASER ABLATION METHOD

    N. A. Zulina

    2015-11-01

    Full Text Available We propose findings for laser ablation of organic materials in liquids as one of the perspective methods of nanoparticles synthesis on their basis. We describe nanoparticles synthesis for 2,6-diaminopyridine-4-nitrophenol (2,6DAP4N cocrystal by the method of material laser ablation at nanoparticles condensation in liquid (dodecane and polyphenyleneoxide. Laser radiation with wavelength equal to 355 nm, pulse duration - 10 ns, pulse repetition rate - 3.8 kHz, and pulse power density equal to 170 kW/cm2 has been used in the study. Nanoparticles in the form of colloids have been obtained and studied by visible range spectroscopy and optical microscopy. Obtained particles size is around 0.5 μm.

  15. Characterization and modeling of 2D-glass micro-machining by spark-assisted chemical engraving (SACE) with constant velocity

    Didar, Tohid Fatanat; Dolatabadi, Ali; Wüthrich, Rolf

    2008-01-01

    Spark-assisted chemical engraving (SACE) is an unconventional micro-machining technology based on electrochemical discharge used for micro-machining nonconductive materials. SACE 2D micro-machining with constant speed was used to machine micro-channels in glass. Parameters affecting the quality and geometry of the micro-channels machined by SACE technology with constant velocity were presented and the effect of each of the parameters was assessed. The effect of chemical etching on the geometry of micro-channels under different machining conditions has been studied, and a model is proposed for characterization of the micro-channels as a function of machining voltage and applied speed

  16. The effect of thermal conductivity of the tool electrode in spark-assisted chemical engraving gravity-feed micro-drilling

    Mousa, M; Allagui, A; Ng, H D; Wüthrich, R

    2009-01-01

    Spark-assisted chemical engraving (SACE) is a non-traditional micro-machining technology based on electrochemical discharge phenomena. In SACE gravity-feed micro-drilling, various parameters including the thermal properties of the tool electrode play a significant role in the process. Based on a series of experiments using tool electrodes with different thermal properties, the effect in SACE gravity-feed micro-drilling is discussed. It is demonstrated that machining with higher thermal conductivity tool electrodes results in faster machining during the discharge regime and slower machining during the hydrodynamic regime of SACE gravity-feed micro-drilling

  17. Nanoparticle-assisted laser desorption/ionization mass spectrometry: Novel sample preparation methods and nanoparticle screening for plant metabolite imaging

    Yagnik, Gargey B. [Iowa State Univ., Ames, IA (United States)

    2016-02-19

    The main goal of the presented research is development of nanoparticle based matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS). This dissertation includes the application of previously developed data acquisition methods, development of novel sample preparation methods, application and comparison of novel nanoparticle matrices, and comparison of two nanoparticle matrix application methods for MALDI-MS and MALDI-MS imaging.

  18. A new method for incoherent combining of far-field laser beams based on multiple faculae recognition

    Ye, Demao; Li, Sichao; Yan, Zhihui; Zhang, Zenan; Liu, Yuan

    2018-03-01

    Compared to coherent beam combining, incoherent beam combining can complete the output of high power laser beam with high efficiency, simple structure, low cost and high thermal damage resistance, and it is easy to realize in engineering. Higher target power is achieved by incoherent beam combination which using technology of multi-channel optical path correction. However, each channel forms a spot in the far field respectively, which cannot form higher laser power density with low overlap ratio of faculae. In order to improve the combat effectiveness of the system, it is necessary to overlap different faculae that improve the target energy density. Hence, a novel method for incoherent combining of far-field laser beams is present. The method compromises piezoelectric ceramic technology and evaluation algorithm of faculae coincidence degree which based on high precision multi-channel optical path correction. The results show that the faculae recognition algorithm is low-latency(less than 10ms), which can meet the needs of practical engineering. Furthermore, the real time focusing ability of far field faculae is improved which was beneficial to the engineering of high-energy laser weapon or other laser jamming systems.

  19. Laser Scanning in Engineering Surveying: Methods of Measurement and Modeling of Structures

    Lenda Grzegorz

    2016-06-01

    Full Text Available The study is devoted to the uses of laser scanning in the field of engineering surveying. It is currently one of the main trends of research which is developed at the Department of Engineering Surveying and Civil Engineering at the Faculty of Mining Surveying and Environmental Engineering of AGH University of Science and Technology in Krakow. They mainly relate to the issues associated with tower and shell structures, infrastructure of rail routes, or development of digital elevation models for a wide range of applications. These issues often require the use of a variety of scanning techniques (stationary, mobile, but the differences also regard the planning of measurement stations and methods of merging point clouds. Significant differences appear during the analysis of point clouds, especially when modeling objects. Analysis of the selected parameters is already possible basing on ad hoc measurements carried out on a point cloud. However, only the construction of three-dimensional models provides complete information about the shape of structures, allows to perform the analysis in any place and reduces the amount of the stored data. Some structures can be modeled in the form of simple axes, sections, or solids, for others it becomes necessary to create sophisticated models of surfaces, depicting local deformations. The examples selected for the study allow to assess the scope of measurement and office work for a variety of uses related to the issue set forth in the title of this study. Additionally, the latest, forward-looking technology was presented - laser scanning performed from Unmanned Aerial Vehicles (drones. Currently, it is basically in the prototype phase, but it might be expected to make a significant progress in numerous applications in the field of engineering surveying.

  20. Novel method of dual fiber Bragg gratings integrated in fiber ring laser for biochemical sensors

    Bui, H.; Pham, T. B.; Nguyen, V. A.; Pham, V. D.; Do, T. C.; Nguyen, T. V.; Hoang, T. H. C.; Le, H. T.; Pham, V. H.

    2018-05-01

    Optical sensors have been shown to be very effective for measuring the toxic content in liquid and air environments. Optical sensors, which operate based on the wavelength shift of the optical signals, require an expensive spectrometer. In this paper, we propose a new configuration of the optical sensor device for measuring wavelength shift without using a spectrometer. This configuration has a large potential for application in biochemical sensing techniques, and comes with a low cost. This configuration uses dual fiber Bragg gratings (FBGs) integrated in a fiber ring laser structure of erbium-doped fiber, in which one FBG is used as a reference to sweep over the applicable spectrum of the etched-Bragg grating. The etched-FBG as a sensing probe is suitable for bio- and/or chemical sensors. The sensitivity and accuracy of the sensor system can be improved by the narrow linewidth of emission spectra from the laser, the best limit of detection of this sensor is 1.5  ×  10‑4 RIU (RIU: refractive index unit), as achieved by the optical sensor using a high resolution spectrometer. This sensor system has been experimentally investigated to detect different types of organic compounds, gasoline, mixing ratios of organic solvents in gasoline, and nitrate concentration in water samples. The experimental results show that this sensing method could determine different mixing ratios of organic solvents with good repeatability, high accuracy, and rapid response: e.g. for ethanol and/or methanol in gasoline RON 92 (RON: research octane number) of 0%–14% v/v, and nitrate in water samples at a low concentration range of 0–50 ppm. These results suggest that the proposed configuration can construct low-cost and accurate biochemical sensors.

  1. Several methods and apparatus of low-energy laser therapy in veterinary practice

    Svirin, Vaytcheslav N.; Rogatkin, Dmitrii A.; Barybin, Vitalii F.

    1998-12-01

    During same years various medical effect of low-energy laser therapy in veterinary were tested. We established that the laser low-energy therapy can be very effective for treatment such animal's diseases as mastitis and demodekose when certain combinations of laser beam parameters are used. This combinations were taken as the principle of a number of laser veterinary apparatus, which we started to produce at `POLUS'. It is our series of apparatus `VEGA-MB' and `VETLAS-3', which is real used today for dogs and cows treatment in Russia.

  2. Method and device for the powerful compression of laser-produced plasmas for nuclear fusion

    Hora, H.

    1975-01-01

    According to the invention, more than 10% of the laser energy are converted into mechanical energy of compression, in that the compression is produced by non-linear excessive radiation pressure. The time and local spectral and intensity distribution of the laser pulse must be controlled. The focussed laser beams must increase to over 10 15 W/cm 2 in less than 10 -9 seconds and the time variation of the intensities must be carried out so that the dynamic absorption of the outer plasma corona by rippling consumes less than 90% of the laser energy. (GG) [de

  3. Applications of laser-photoacoustic gas analysis method; Fotoakustisen kaasuanalyysin sovelluksia. Fotoakustiset mittaukset paineistetussa poelyvirtausreaktorissa

    Hernberg, R.; Stenberg, J. [Tampere Univ. of Technology (Finland). Lab. of Plasma Technology

    1997-10-01

    Laser induced photoacoustic spectroscopy has been developed in LIEKKI and LIEKKI 2 research programs. The method is intended for In-Situ analysis of gaseous components in hot and reactive environments such as combustion conditions. The method and the instrumentation developed in this project have been calibrated for SO{sub 2}, NO, NO{sub 2}, NH{sub 3}, N{sub 2}O, and H{sub 2}S between 20 and 860 deg C at atmospheric pressure. Calibrations at elevated pressures have been performed for NO{sub 2}, NO, SO{sub 2}, NH{sub 3} and N{sub 2}O. Calibration for OH radical has also been performed. A known concentration of OH was generated by thermally decomposing H{sub 2}O at temperatures between 900 and 1050 deg C. The photoacoustic method has earlier been applied to the chemical analysis of burning CH{sub 4}/HCN/O{sub 2}/N{sub 2} flame at pressures between 1 and 6 bar. The formation of NO and NH{sub 3} measured in post-flame conditions. The relative concentration of OH in the reactive zone of the flame was measured between 1 and 6 bar pressures. The method was also applied to measurements in circulating fluidized bed (CFB). Time resolved gas concentrations were measured at three different heights above the air distributor with a specialized probe. In this project the photoacoustic method is applied in studies regarding the effect of chlorine (Cl) on combustion chemistry. The second goal of this project is to make In-Situ measurements of the formation of NO{sub 2} in combustion. The formation of NO{sub 2} increases strongly at elevated pressures. Due to the instability of NO{sub 2} the analysis is prone to errors with conventional gas sampling probes

  4. Realistic PIC modelling of laser-plasma interaction: a direct implicit method with adjustable damping and high order weight functions

    Drouin, M.

    2009-11-01

    This research thesis proposes a new formulation of the relativistic implicit direct method, based on the weak formulation of the wave equation which is solved by means of a Newton algorithm. The first part of this thesis deals with the properties of the explicit particle-in-cell (PIC) methods: properties and limitations of an explicit PIC code, linear analysis of a numerical plasma, numerical heating phenomenon, interest of a higher order interpolation function, and presentation of two applications in high density relativistic laser-plasma interaction. The second and main part of this report deals with adapting the direct implicit method to laser-plasma interaction: presentation of the state of the art, formulating of the direct implicit method, resolution of the wave equation. The third part concerns various numerical and physical validations of the ELIXIRS code: case of laser wave propagation in vacuum, demonstration of the adjustable damping which is a characteristic of the proposed algorithm, influence of space-time discretization on energy conservation, expansion of a thermal plasma in vacuum, two cases of plasma-beam unsteadiness in relativistic regime, and then a case of the overcritical laser-plasma interaction

  5. A mathematical model and an approximate method for calculating the fracture characteristics of nonmetallic materials during laser cutting

    Smorodin, F.K.; Druzhinin, G.V.

    1991-01-01

    A mathematical model is proposed which describes the fracture behavior of amorphous materials during laser cutting. The model, which is based on boundary layer equations, is reduced to ordinary differential equations with the corresponding boundary conditions. The reduced model is used to develop an approximate method for calculating the fracture characteristics of nonmetallic materials.

  6. Electron density profile reconstruction by maximum entropy method with multichannel HCN laser interferometer system on SPAC VII

    Kubo, S.; Narihara, K.; Tomita, Y.; Hasegawa, M.; Tsuzuki, T.; Mohri, A.

    1988-01-01

    A multichannel HCN laser interferometer system has been developed to investigate the plasma electron confinement properties in SPAC VII device. Maximum entropy method is applied to reconstruct the electron density profile from measured line integrated data. Particle diffusion coefficient in the peripheral region of the REB ring core spherator was obtained from the evolution of the density profile. (author)

  7. Use of lasers in the furniture industry

    Wieloch, Grzegorz; Pohl, Piotr

    1995-03-01

    One of the ways of using laser in industry is its usage in loss treatment of wood and composite wood products. In the furniture industry the above mentioned machining is used in such technological processes in which tool machining (sawing, molding) is not economical or even possible. These processes are mainly curvilinear cutting of layer materials like veneers, plywood, and face layers and thicker materials like particleboards, fiberboards, and lumber- core panels. Wide usage has also been achieved in heat treatment in wood for decoration. It can be calcinating designs, engraving them, blackening of parts of surfaces, or changing of anatomic characteristics of wood tissue. Nevertheless laser usage in recliner cutting seems at present causeless.

  8. Lattice Boltzmann method for short-pulsed laser transport in a multi-layered medium

    Zhang, Yong; Yi, Hong-Liang; Tan, He-Ping

    2015-01-01

    We construct a lattice Boltzmann method (LBM) for transient radiative transfer in one-dimensional multi-layered medium with distinct refractive index in each layer. The left boundary is irradiated normally by a short-pulsed laser. The Fresnel interfaces conditions, which incorporate reflection and refraction, are used at the boundaries and the interfaces. Based on the Fresnel's law and Snell's law, the interfacial intensity formulas are introduced. The collimated and diffuse intensities are treated individually. At a transient time step, the collimated component is first solved by LBM and then embedded into the transient radiative transfer equation as a source term. To keep the consistency of the directions in all the layers, angular interpolation of the intensities at the interfaces is adopted. The transient radiative transfer in a two-layer medium is first investigated, and the time-resolved results are validated by comparing with those by the Monte Carlo method (MCM). Of particular interest, the angular intensities along the slab at different times are presented to illustrate a variety of interesting phenomena, and the discontinuous nature of the intensity at the interfaces is discussed. The effects of various parameters on the time-resolved signals are examined. - Highlights: • Transient radiative transfer in a multi-layered medium is solved by LBM. • The boundary and interfaces are all considered as Fresnel surfaces. • The LBM solution for the collimated pulse is derived. • Discontinuous nature of the intensity at the interface is illustrated and discussed

  9. Classical Measurement Methods and Laser Scanning Usage in Shaft Hoist Assembly Inventory

    Jaśkowski Wojciech

    2018-01-01

    Full Text Available The shaft hoist assembly is the base of underground mining plant. Its efficiency and correct operation is subject to restrictive legal regulations and is controlled on a daily visual assessment by shaft crew and energomechanics. In addition, in the regular interval, the shaft hoist assembly is subject to a thorough inventory, which includes the determination of the geometrical relationships between the hoisting machine, the headframe and the shaft with its housing. Inventory measurements for shaft and headframe are used for years of conventional geodetic methods including mechanical or laser plumbing and tachymetric surveys. Additional precision levelling is also used for measuring shafts of hoisting machines and rope pulleys. Continuous modernization of measuring technology makes it possible to implement the further methods to the above mentioned purposes. The comparison of the accuracy and the economics of performing measurements based on many years of experience with comprehensive inventory of shaft hoist assembly using various research techniques was made and detailed in the article.

  10. Revised method for forest canopy height estimation from Geoscience Laser Altimeter System waveforms.

    Michael A. Lefskya; Michael Keller; Yong Panga; Plinio B. de Camargod; Maria O. Hunter

    2007-01-01

    The vertical extent of waveforms collected by the Geoscience Laser Altimeter System (onboard ICESat - the Ice, Cloud, and land Elevation Satellite) increases as a function of terrain slope and footprint size (the area on the ground that is illuminated by the laser). Over sloped terrain, returns from both canopy and ground surfaces can occur at the same elevation. As a...

  11. Parameters nanodimensional zinc films deposited by the laser method in vacuum

    Goncharov, V.K.; Gusakov, G.A.; Puzyrev, M.V.

    2013-01-01

    The investigation of the thickness and structure of a zinc films surface produced by the laser-plasma deposition has been carried out. The dependence of a film thickness and surface structure from laser radiation intensity has been determined. Threshold intensity has been determined when an evaporation of a target material begins. (authors)

  12. THE DEVELOPMENT OF TECHNOLOGICAL METHODS OF LASER SURFACE TREATMENT OF HEAVILY LOADED PARTS WHEEL SET CARS

    V. D. Sheliahin

    2009-06-01

    Full Text Available Possibility of application of processes of laser superficial processing for restoration and increase of a resource of operation of shafts and rims of wheels of railway cars is investigated. The influence of critical parametres of process on depth of a zone of laser influence and their interrelation with the structure obtained and hardness is determineed.

  13. 3D Laser Imprint Using a Smoother Ray-Traced Power Deposition Method

    Schmitt, Andrew J.

    2017-10-01

    Imprinting of laser nonuniformities in directly-driven icf targets is a challenging problem to accurately simulate with large radiation-hydro codes. One of the most challenging aspects is the proper construction of the complex and rapidly changing laser interference structure driving the imprint using the reduced laser propagation models (usually ray-tracing) found in these codes. We have upgraded the modelling capability in our massively-parallel fastrad3d code by adding a more realistic EM-wave interference structure. This interference model adds an axial laser speckle to the previous transverse-only laser structure, and can be impressed on our improved smoothed 3D raytrace package. This latter package, which connects rays to form bundles and performs power deposition calculations on the bundles, is intended to decrease ray-trace noise (which can mask or add to imprint) while using fewer rays. We apply this improved model to 3D simulations of recent imprint experiments performed on the Omega-EP laser and the Nike laser that examined the reduction of imprinting due to very thin high-Z target coatings. We report on the conditions in which this new model makes a significant impact on the development of laser imprint. Supported by US DoE/NNSA.

  14. Parameters of nanodimensional aluminium films deposited by the laser method in vacuum

    Gusakov, G.A.; Ismailov, D.R.; Puzyrev, M.V.

    2011-01-01

    The investigation of the thickness and structure of a aluminium films surface produced by the laser-plasma deposition has been carried out. The dependence of a film thickness from laser radiation intensity has been determined. Threshold intensity has been determined when an evaporation of a target material begins. (authors)

  15. Observation of coherent optical phonons excited by femtosecond laser radiation in Sb films by ultrafast electron diffraction method

    Mironov, B. N.; Kompanets, V. O.; Aseev, S. A., E-mail: isanfemto@yandex.ru [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation); Ischenko, A. A. [Moscow Technological University, Institute of High Chemical Technologies (Russian Federation); Kochikov, I. V. [Moscow State University (Russian Federation); Misochko, O. V. [Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation); Chekalin, S. V.; Ryabov, E. A. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation)

    2017-03-15

    The generation of coherent optical phonons in a polycrystalline antimony film sample has been investigated using femtosecond electron diffraction method. Phonon vibrations have been induced in the Sb sample by the main harmonic of a femtosecond Ti:Sa laser (λ = 800 nm) and probed by a pulsed ultrashort photoelectron beam synchronized with the pump laser. The diffraction patterns recorded at different times relative to the pump laser pulse display oscillations of electron diffraction intensity corresponding to the frequencies of vibrations of optical phonons: totally symmetric (A{sub 1g}) and twofold degenerate (E{sub g}) phonon modes. The frequencies that correspond to combinations of these phonon modes in the Sb sample have also been experimentally observed.

  16. Patterning of metallic electrodes on flexible substrates for organic thin-film transistors using a laser thermal printing method

    Chen, Kun-Tso; Lin, Yu-Hsuan; Ho, Jeng-Rong; Chen, Chih-Kant; Liu, Sung-Ho; Liao, Jin-Long; Cheng, Hua-Chi

    2011-01-01

    We report on a laser thermal printing method for transferring patterned metallic thin films on flexible plastic substrates using a pulsed CO 2 laser. Aluminium and silver line patterns, with micrometre scale resolution on poly(ethylene terephthalate) substrates, are shown. The printed electrodes demonstrate good conductivity and fulfil the properties for bottom-contact organic thin-film transistors. In addition to providing the energy for transferring the film, the absorption of laser light results in a rise in the temperature of the film and the substrate. This also further anneals the film and softens the plastic substrate. Consequently, it is possible to obtain a film with better surface morphology and with its film thickness implanted in part into the plastic surface. This implantation reveals excellent characteristics in adhesion and flexure resistance. Being feasible to various substrates and executable at ambient temperatures renders this approach a potential alternative for patterning metallic electrodes.

  17. Comparison of Ultrasonic and CO2 Laser Pretreatment Methods on Enzyme Digestibility of Corn Stover

    Li-Li Zuo

    2012-03-01

    Full Text Available To decrease the cost of bioethanol production, biomass recalcitrance needs to be overcome so that the conversion of biomass to bioethanol becomes more efficient. CO2 laser irradiation can disrupt the lignocellulosic physical structure and reduce the average size of fiber. Analyses with Fourier transform infrared spectroscopy, specific surface area, and the microstructure of corn stover were used to elucidate the enhancement mechanism of the pretreatment process by CO2 laser irradiation. The present work demonstrated that the CO2 laser had potential to enhance the bioconversion efficiency of lignocellulosic waste to renewable bioethanol. The saccharification rate of the CO2 laser pretreatment was significantly higher than ultrasonic pretreatment, and reached 27.75% which was 1.34-fold of that of ultrasonic pretreatment. The results showed the impact of CO2 laser pretreatment on corn stover to be more effective than ultrasonic pretreatment.

  18. A new method to butt weld pipes with laser at different angles

    Gualini, M.M.S.

    1999-01-01

    Laser butt welding of pipes at different angles may be cumbersome and may require very expensive tooling. The pipe size may not allow using the laser for large volume throughputs. We propose a rotary optical head composed by an adjustable focus lens system and two reflecting mirrors. The laser beam is bent at 90 deg. C. so that weld can be performed inwards outwards. The optic head design compensates the rotary backlash and vibrations, like a penta prism thus ensuring a perfect follow up of the weld track. The optic head can be inclined at 45 deg. C. to laser butt weld pipe each other at 90 deg. C. In this case the laser beam focus position is computer controlled in order to keep the focus point always on the elliptical weld profile. The paper covers theoretical and practical aspects of the proposed device. (author)

  19. Comparison of ultrasonic and CO₂laser pretreatment methods on enzyme digestibility of corn stover.

    Tian, Shuang-Qi; Wang, Zhen-Yu; Fan, Zi-Luan; Zuo, Li-Li

    2012-01-01

    To decrease the cost of bioethanol production, biomass recalcitrance needs to be overcome so that the conversion of biomass to bioethanol becomes more efficient. CO(2) laser irradiation can disrupt the lignocellulosic physical structure and reduce the average size of fiber. Analyses with Fourier transform infrared spectroscopy, specific surface area, and the microstructure of corn stover were used to elucidate the enhancement mechanism of the pretreatment process by CO(2) laser irradiation. The present work demonstrated that the CO(2) laser had potential to enhance the bioconversion efficiency of lignocellulosic waste to renewable bioethanol. The saccharification rate of the CO(2) laser pretreatment was significantly higher than ultrasonic pretreatment, and reached 27.75% which was 1.34-fold of that of ultrasonic pretreatment. The results showed the impact of CO(2) laser pretreatment on corn stover to be more effective than ultrasonic pretreatment.

  20. Optimisation Of Cutting Parameters Of Composite Material Laser Cutting Process By Taguchi Method

    Lokesh, S.; Niresh, J.; Neelakrishnan, S.; Rahul, S. P. Deepak

    2018-03-01

    The aim of this work is to develop a laser cutting process model that can predict the relationship between the process input parameters and resultant surface roughness, kerf width characteristics. The research conduct is based on the Design of Experiment (DOE) analysis. Response Surface Methodology (RSM) is used in this work. It is one of the most practical and most effective techniques to develop a process model. Even though RSM has been used for the optimization of the laser process, this research investigates laser cutting of materials like Composite wood (veneer)to be best circumstances of laser cutting using RSM process. The input parameters evaluated are focal length, power supply and cutting speed, the output responses being kerf width, surface roughness, temperature. To efficiently optimize and customize the kerf width and surface roughness characteristics, a machine laser cutting process model using Taguchi L9 orthogonal methodology was proposed.

  1. Thermoelastic Stress Field Investigation of GaN Material for Laser Lift-off Technique based on Finite Element Method

    Ting, Wang; Zhan-Zhong, Cui; Li-Xin, Xu

    2009-01-01

    The transient thermoelastic stress fields of GaN films is analyzed by the finite element method for the laser lift-off (LLO) technique. Stress distributions in GaN films irradiated by pulse laser with different energy densities as functions of time and depth are simulated. The results show that the high thermoelastic stress distributions in GaN films localize within about 1 μm below the GaN/Al 2 O 3 interface using proper laser parameters. It is also found that GaN films can avoid the thermal deformation because the maximum thermoelastic stress 4.28 GPa is much smaller than the yield strength of GaN 15GPa. The effects of laser beam dimension and the thickness of GaN films on stress distribution are also analyzed. The variation range of laser beam dimension as a function of the thickness of GaN films is simulated to keep the GaN films free of thermal deformation. LLO experiments are also carried out. GaN-based light-emitting diodes (LEDs) are separated from sapphire substrates using the parameters obtained from the simulation. Compared with devices before LLO, P–I–V measurements of GaN-based LEDs after LLO show that the electrical and optical characteristics improve greatly, indicating that no stress damage is brought to GaN films using proper parameters obtained by calculation during LLO

  2. Comparison of Microleakage of Glass Ionomer Restoration in Primary Teeth Prepared by Er: YAG Laser and the Conventional Method

    M. Ghandehari

    2012-01-01

    Full Text Available Objective: One of the main criteria in evaluating the restorative materials is the degree of microleakage. The aim of this study was to compare the microleakage of glass ionomer restored cavities prepared by Er:YAG laser or turbine and bur.Materials and Methods: Twenty extracted caries-free deciduous posterior teeth were selected for this study. The teeth were randomly divided into two groups for cavity preparation. Cavities in group one were prepared by high speed turbine and bur. In the second group, Er:YAG laser with a 3W output power, 300 mJ energy and 10 Hz frequency was used. Cavities were restored with GC Fuji II LC. After thermocycling, the samples were immersed into 0.5% methylene blue solution. They were sectioned for examination under optic microscope.Results: The Wilcoxon signed ranks test showed no significant difference between microleakage of the laser group and the conventional group (P>0.05.Conclusion: Er:YAG laser with its advantages in pediatric dentistry may be suggested as an alternative device for cavity preparation.Key Words: Er:YAG laser, Glass ionomer, Microleakage

  3. Clustering and training set selection methods for improving the accuracy of quantitative laser induced breakdown spectroscopy

    Anderson, Ryan B.; Bell, James F.; Wiens, Roger C.; Morris, Richard V.; Clegg, Samuel M.

    2012-01-01

    We investigated five clustering and training set selection methods to improve the accuracy of quantitative chemical analysis of geologic samples by laser induced breakdown spectroscopy (LIBS) using partial least squares (PLS) regression. The LIBS spectra were previously acquired for 195 rock slabs and 31 pressed powder geostandards under 7 Torr CO 2 at a stand-off distance of 7 m at 17 mJ per pulse to simulate the operational conditions of the ChemCam LIBS instrument on the Mars Science Laboratory Curiosity rover. The clustering and training set selection methods, which do not require prior knowledge of the chemical composition of the test-set samples, are based on grouping similar spectra and selecting appropriate training spectra for the partial least squares (PLS2) model. These methods were: (1) hierarchical clustering of the full set of training spectra and selection of a subset for use in training; (2) k-means clustering of all spectra and generation of PLS2 models based on the training samples within each cluster; (3) iterative use of PLS2 to predict sample composition and k-means clustering of the predicted compositions to subdivide the groups of spectra; (4) soft independent modeling of class analogy (SIMCA) classification of spectra, and generation of PLS2 models based on the training samples within each class; (5) use of Bayesian information criteria (BIC) to determine an optimal number of clusters and generation of PLS2 models based on the training samples within each cluster. The iterative method and the k-means method using 5 clusters showed the best performance, improving the absolute quadrature root mean squared error (RMSE) by ∼ 3 wt.%. The statistical significance of these improvements was ∼ 85%. Our results show that although clustering methods can modestly improve results, a large and diverse training set is the most reliable way to improve the accuracy of quantitative LIBS. In particular, additional sulfate standards and specifically

  4. A Classification-oriented Method of Feature Image Generation for Vehicle-borne Laser Scanning Point Clouds

    YANG Bisheng

    2016-02-01

    Full Text Available An efficient method of feature image generation of point clouds to automatically classify dense point clouds into different categories is proposed, such as terrain points, building points. The method first uses planar projection to sort points into different grids, then calculates the weights and feature values of grids according to the distribution of laser scanning points, and finally generates the feature image of point clouds. Thus, the proposed method adopts contour extraction and tracing means to extract the boundaries and point clouds of man-made objects (e.g. buildings and trees in 3D based on the image generated. Experiments show that the proposed method provides a promising solution for classifying and extracting man-made objects from vehicle-borne laser scanning point clouds.

  5. A novel weld seam detection method for space weld seam of narrow butt joint in laser welding

    Shao, Wen Jun; Huang, Yu; Zhang, Yong

    2018-02-01

    Structured light measurement is widely used for weld seam detection owing to its high measurement precision and robust. However, there is nearly no geometrical deformation of the stripe projected onto weld face, whose seam width is less than 0.1 mm and without misalignment. So, it's very difficult to ensure an exact retrieval of the seam feature. This issue is raised as laser welding for butt joint of thin metal plate is widely applied. Moreover, measurement for the seam width, seam center and the normal vector of the weld face at the same time during welding process is of great importance to the welding quality but rarely reported. Consequently, a seam measurement method based on vision sensor for space weld seam of narrow butt joint is proposed in this article. Three laser stripes with different wave length are project on the weldment, in which two red laser stripes are designed and used to measure the three dimensional profile of the weld face by the principle of optical triangulation, and the third green laser stripe is used as light source to measure the edge and the centerline of the seam by the principle of passive vision sensor. The corresponding image process algorithm is proposed to extract the centerline of the red laser stripes as well as the seam feature. All these three laser stripes are captured and processed in a single image so that the three dimensional position of the space weld seam can be obtained simultaneously. Finally, the result of experiment reveals that the proposed method can meet the precision demand of space narrow butt joint.

  6. The reality of virtual anthropology: Comparing digitizer and laser scan data collection methods for the quantitative assessment of the cranium.

    Algee-Hewitt, Bridget F B; Wheat, Amber D

    2016-05-01

    The use of geometric morphometry to study cranial variation has steadily grown in appeal over the past decade in biological anthropology. Publication trends suggest that the most popular methods for three-dimensional data acquisition involve landmark-based coordinate data collection using a digitizer. Newer laser scan approaches are seeing increasing use, owing to the benefits that densely sampled data offer. While both of these methods have their utility, research that investigates their compatibility is lacking. The purpose of this project is to compare, quantitatively, craniometrics collected with a digitizer against data extracted from laser scans using the same individuals and laboratory conditions. Three-dimensional (x,y,z) coordinates and traditional inter-landmark distances (ILDs) were obtained with a Microscribe digitizer and 360° color models produced from NextEngine laser scans for 38 adult crania representing five cemeteries from the ADBOU skeletal collection in Denmark. Variance-based tests were performed to evaluate the disagreement between data collected with a digitizer and from laser scan models. Consideration was given to differences among landmarks by type, between ILDs calculated from landmark coordinates, and in morphology for the cemetery populations. Further, the reliability of laser scan data collection was assessed by intra-observer error tests. Researchers should be aware of the potential error associated with the use of Types II and III landmarks and the limitations on reliability imposed by object-to-scanner placement. This project reveals how laser scans can provide a valuable digital archive of cranial material that can be reasonably exploited for the "virtual" collection of coordinates and the calculation of ILDs. © 2015 Wiley Periodicals, Inc.

  7. Numerical simulations used for a validity check on the laser induced photo-detachment diagnostic method in electronegative plasmas

    Oudini, N. [Laboratoire des plasmas de décharges, Centre de Développement des Technologies Avancées, Cité du 20 Aout BP 17 Baba Hassen, 16081 Algiers (Algeria); Taccogna, F. [Istituto di Metodologie Inorganiche e dei Plasmi, CNR, via Amendola 122/D, 70126 Bari (Italy); Bendib, A. [Laboratoire d' Electronique Quantique, Faculté de Physique, USTHB, El Alia BP 32, Bab Ezzouar 16111, Algiers (Algeria); Aanesland, A. [Laboratoire de Physique des Plasmas (CNRS, Ecole Polytechnique, Sorbonne Universités, UPMC Univ Paris 06, Univ Paris-Sud), École Polytechnique, 91128 Palaiseau Cedex (France)

    2014-06-15

    Laser photo-detachment is used as a method to measure or determine the negative ion density and temperature in electronegative plasmas. In essence, the method consists of producing an electropositive channel (negative ion free region) via pulsed laser photo-detachment within an electronegative plasma bulk. Electrostatic probes placed in this channel measure the change in the electron density. A second pulse might be used to track the negative ion recovery. From this, the negative ion density and temperature can be determined. We study the formation and relaxation of the electropositive channel via a two-dimensional Particle-In-Cell/Mote Carlo collision model. The simulation is mainly carried out in a Hydrogen plasma with an electronegativity of α = 1, with a parametric study for α up to 20. The temporal and spatial evolution of the plasma potential and the electron densities shows the formation of a double layer (DL) confining the photo-detached electrons within the electropositive channel. This DL evolves into two fronts that move in the opposite directions inside and outside of the laser spot region. As a consequence, within the laser spot region, the background and photo-detached electron energy distribution function relaxes/thermalizes via collisionless effects such as Fermi acceleration and Landau damping. Moreover, the simulations show that collisional effects and the DL electric field strength might play a non-negligible role in the negative ion recovery within the laser spot region, leading to a two-temperature negative ion distribution. The latter result might have important effects in the determination of the negative ion density and temperature from laser photo detachment diagnostic.

  8. Injection Methods and Instrumentation for Serial X-ray Free Electron Laser Experiments

    James, Daniel

    Scientists have used X-rays to study biological molecules for nearly a century. Now with the X-ray free electron laser (XFEL), new methods have been developed to advance structural biology. These new methods include serial femtosecond crystallography, single particle imaging, solution scattering, and time resolved techniques. The XFEL is characterized by high intensity pulses, which are only about 50 femtoseconds in duration. The intensity allows for scattering from microscopic particles, while the short pulses offer a way to outrun radiation damage. XFELs are powerful enough to obliterate most samples in a single pulse. While this allows for a "diffract and destroy" methodology, it also requires instrumentation that can position microscopic particles into the X-ray beam (which may also be microscopic), continuously renew the sample after each pulse, and maintain sample viability during data collection. Typically these experiments have used liquid microjets to continuously renew sample. The high flow rate associated with liquid microjets requires large amounts of sample, most of which runs to waste between pulses. An injector designed to stream a viscous gel-like material called lipidic cubic phase (LCP) was developed to address this problem. LCP, commonly used as a growth medium for membrane protein crystals, lends itself to low flow rate jetting and so reduces the amount of sample wasted significantly. This work discusses sample delivery and injection for XFEL experiments. It reviews the liquid microjet method extensively, and presents the LCP injector as a novel device for serial crystallography, including detailed protocols for the LCP injector and anti-settler operation.

  9. Comparison of some effects of modification of a polylactide surface layer by chemical, plasma, and laser methods

    Moraczewski, Krzysztof, E-mail: kmm@ukw.edu.pl [Department of Materials Engineering, Kazimierz Wielki University, Department of Materials Engineering, ul. Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Rytlewski, Piotr [Department of Materials Engineering, Kazimierz Wielki University, Department of Materials Engineering, ul. Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Malinowski, Rafał [Institute for Engineering of Polymer Materials and Dyes, ul. M. Skłodowskiej–Curie 55, 87-100 Toruń (Poland); Żenkiewicz, Marian [Department of Materials Engineering, Kazimierz Wielki University, Department of Materials Engineering, ul. Chodkiewicza 30, 85-064 Bydgoszcz (Poland)

    2015-08-15

    Highlights: • We modified polylactide surface layer with chemical, plasma or laser methods. • We tested selected properties and surface structure of modified samples. • We stated that the plasma treatment appears to be the most beneficial. - Abstract: The article presents the results of studies and comparison of selected properties of the modified PLA surface layer. The modification was carried out with three methods. In the chemical method, a 0.25 M solution of sodium hydroxide in water and ethanol was utilized. In the plasma method, a 50 W generator was used, which produced plasma in the air atmosphere under reduced pressure. In the laser method, a pulsed ArF excimer laser with fluency of 60 mJ/cm{sup 2} was applied. Polylactide samples were examined by using the following techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and X-ray photoelectron spectroscopy (XPS). Images of surfaces of the modified samples were recorded, contact angles were measured, and surface free energy was calculated. Qualitative and quantitative analyses of chemical composition of the PLA surface layer were performed as well. Based on the survey it was found that the best modification results are obtained using the plasma method.

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

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

    2000-05-01

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

  11. AN AUTOMATED METHOD FOR 3D ROOF OUTLINE GENERATION AND REGULARIZATION IN AIRBONE LASER SCANNER DATA

    S. N. Perera

    2012-07-01

    Full Text Available In this paper, an automatic approach for the generation and regularization of 3D roof boundaries in Airborne Laser scanner data is presented. The workflow is commenced by segmentation of the point clouds. A classification step and a rule based roof extraction step are followed the planar segmentation. Refinement on roof extraction is performed in order to minimize the effect due to urban vegetation. Boundary points of the connected roof planes are extracted and fitted series of straight line segments. Each line is then regularized with respect to the dominant building orientation. We introduce the usage of cycle graphs for the best use of topological information. Ridge-lines and step-edges are basically extracted to recognise correct topological relationships among the roof faces. Inner roof corners are geometrically fitted based on the closed cycle graphs. Outer boundary is reconstructed using the same concept but with the outer most cycle graph. In here, union of the sub cycles is taken. Intermediate line segments (outer bounds are intersected to reconstruct the roof eave lines. Two test areas with two different point densities are tested with the developed approach. Performance analysis of the test results is provided to demonstrate the applicability of the method.

  12. Effect of solution composition on determination of uranium (6) microquantities by laser-induced luminescence method

    Romanovskaya, G.I.; Zakharova, G.V.; Chibisova, A.K.

    1984-01-01

    The effect of cation and anion composition of natural waters (sea water, ground water, etc.) on the uranium (6) determination in the form of uranyl complexes with Na 2 O3SiO 2 using the laser-induced luminescence method with the determination limit 2x10 -11 g/ml, has been studied. The dependence of the luminescence intensity of uranyl polysilicate complexes on the inorganic ion concentration has been measured. The measurement results permitted to determine the maximum permissible concentrations (MAC) of ions, the values of which are presented. The results reproducibility is characterized by a relative standard deveation within 0.01-0.05. It follows from the data analysis that the MPC of impurities vary from 10 -8 to 10 -2 g/ml. The MPCs of uranium as determined in the form of polysilicate complexes, are shown to be close to the values obtained during uranium determination in the form of complexes with fluoran for the CO 3 2- , Ni, Cu ions and they are by an order higher for the Na, K, Cl - , SO 4 2- , HPO 4 2- , Mn ions

  13. Investigation of ZnTe thin films grown by Pulsed Laser Deposition method

    Kotlyarchuk, B.; Savchuk, V.

    2007-01-01

    This paper is devoted to optimization of the Pulsed Laser Deposition (PLD) growth condition of ZnTe films on various substrates and subsequent investigation of relevant parameters of growth process, structural, optical and electrical properties of grown films. Studies of the effect of growth parameters on the structural quality and properties of grown films were carried out. X-ray diffraction measurements showed that the ZnTe films, which have been deposited at optimal substrate temperatures, were characterized by a (111) preferred orientation with large average grain size. The optical transmission and reflectance in the energy range 1.5-5.5 eV for films grown at various substrate temperatures were measured. We calculated the variation in the absorption coefficient with the photon energy from the transmittance spectrum for samples grown at various substrate temperatures. Obtained data were analyzed and the value of the absorption coefficient, for allowed direct transitions, has been determined as a function of photon energy. We found that the undoped ZnTe films, which were grown by the PLD method, are typically p-type and possess resistivity in the range of 10 3 Ωcm at room temperature. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. The Light Plane Calibration Method of the Laser Welding Vision Monitoring System

    Wang, B. G.; Wu, M. H.; Jia, W. P.

    2018-03-01

    According to the aerospace and automobile industry, the sheet steels are the very important parts. In the recent years, laser welding technique had been used to weld the sheet steel part. The seam width between the two parts is usually less than 0.1mm. Because the error of the fixture fixed can’t be eliminated, the welding parts quality can be greatly affected. In order to improve the welding quality, the line structured light is employed in the vision monitoring system to plan the welding path before welding. In order to improve the weld precision, the vision system is located on Z axis of the computer numerical control (CNC) tool. The planar pattern is placed on the X-Y plane of the CNC tool, and the structured light is projected on the planar pattern. The vision system stay at three different positions along the Z axis of the CNC tool, and the camera shoot the image of the planar pattern at every position. Using the calculated the sub-pixel center line of the structure light, the world coordinate of the center light line can be calculated. Thus, the structured light plane can be calculated by fitting the structured light line. Experiment result shows the effective of the proposed method.

  15. Laser fluorescent method for monitoring leaks from petrol pipes based on the neural network algorithm

    M. L. Belov

    2014-01-01

    Full Text Available Current systems for monitoring leaks from petrol pipes can detect large leaks only, and their sensitivity limit is about 1% of the whole petrol pipe’s capacity. In this paper, a problem of remote detection of small leaks (less than 1% from petrol pipes was considered. One of possible variations of such a system is a monitoring system of oil pollution at the earth surface along the petrol pipe. In this paper experimentally obtained data such as fluorescence spectra of oil products (crude oil, light-end oil products, heavy oil products, various earth surfaces (soil, vegetation, water, asphalt and oil products spilled over various earth's surface were used for the excitation wavelength of 266 nm. It was shown that use of the laser method based on detection of fluorescence radiation within three narrow spectral bands and a neural network algorithm of measured data processing allowed one to detect oil pollution on the earth surface with a probability of correct classification close to 1 and low probability of false alarm.

  16. Novel method to measure the soil clay’s permeability by laser interferometry

    Asselman H.

    2014-04-01

    Full Text Available In this study, we’ll present a new method to measure the permeability of clay soils (or infiltration rate by laser interferometry. The device is a modified Michelson interferometer. Indeed on the movable mirror is glued a clay sample in the form of a parallelepiped, dried, of length L, height H and shaped to retain the drops of water on its surface to control water’s content .When injecting a volume of distilled water (a few drops to the surface of the sample, it swells and moves the mirror, then we can measure the swelling depending on the depth of a clay soil and its permeability. Therefore we measure time that takes water to reach a depth of Z and we determine the infiltration rate: V=6μm/s ± 3% in concordance with literal values included between 2,8 and 13,9μm/s in clayey silt. For this comparison, we used the study of the characterization of the clay fraction to our sample by XRD.

  17. Selective laser pyrolysis of metallo-organics as a method of forming patterned thin film superconductors

    Mantese, J.V.; Catalan, A.B.; Sell, J.A.; Meyer, M.S.; Mance, A.M.

    1990-01-01

    This patent describes a method for forming patterned films of superconductive materials forming a solution from the neodecanoates of yttrium, barium and copper. The neodecanoates forming an oxide mixture exhibiting superconductive properties upon subsequent thermal decompositions wherein the oxide mixture is characterized by a ratio of yttrium:barium:copper of approximately 1:2:4, the solution comprising an organic solvent such as xylene; adding to the solution an appropriate dye, depositing a film of the solution having the dye onto a strontium titanate substrate; exposing selective regions of the film with an Argon laser emitting the wavelength of light, such that the exposed regions of the film become insoluble in the xylene; immersing the film into the xylene so that the soluble; unexposed regions of the film are removed from the substrate; heating the film to thermally decompose the neodecanoates into a film containing yttrium, barium and copper oxides; to promote recrystallization and grain growth of the metal oxides within the film and induce a change therein by which the film exhibits superconducting properties

  18. A novel DWDM method to design a 100-kW Laser

    Basu, Santanu

    2010-02-01

    In this paper, I will present the design analysis of a novel concept that may be used to generate a diffraction-limited beam from an aperture so that as much as 450 kW of laser power can be efficiently deposited on a diffraction-limited spot at a range. The laser beam will be comprised of many closely spaced wavelength channels as in a DWDM. The technique relies on the ability of an angular dispersion amplifier to multiplex a large number of high power narrow frequency lasers, wavelengths of which may be as close as 0.4 nm.

  19. Laser induced florescence: application to spectroscopy and new microscopy imaging methods

    Galaup, L. P.

    2012-01-01

    Laser induced fluorescence is one of the light using techniques which allows the highest sensitivity for atoms and molecules detection, up to the single atom or single molecule level. This field is much too large for an extensive review; therefor we have chosen to focus on two main points: 1- the observation of laser stimulated fluorescence in phthalocyanine and porphyrin like molecules in rare gas and nitrogen matrices at low temperatures. 2- the presentation of laser induced fluorescence techniques suitable for achieving ultra-high spatial resolution imaging, below the diffraction limit of conventional microscopy, thanks to highly fluorescent molecules to be used as biological markers. (Author)

  20. A novel and simple method for analyzing elements using x-ray induced with femto-second laser

    Fukushima, M.; Yomogihata, K.; Ono, H.; Hatanaka, K.; Fukumura, H.

    2005-01-01

    It is well known that x-ray emission is induced when materials are irradiated by an intense femto-second laser. Since the x-ray properties of atoms are almost independent of chemical forms or physical states, the induced x-ray emission spectrum is useful for analytical purposes. A new and simple method for analyzing elements in solid and liquid samples has been developed using a femto-second laser with sufficient power to generate x-ray emission. Femto-second pulses from a Ti: sapphire laser system were focused with a microscopic objective lens on samples, and x-ray emission spectra were measured by solid state detector. Though the sensitivity for elements is not so high, this method has several advantages; (1) available to analyze under daylight, (2) available to analyze in the air, (3) no need for the license to radioactive source. Moreover, this laser system can be taken to outside. It means this method can be used for in site analysis. Various kinds of samples were tested; commercial crystal glass, NIST SRM-1633b Coal Fly Ash: GSJ Reference Sample JMn-1 Mn nodule sample, several kinds of geological rocks, law fish slice, and gelatin gel of salt solutions. As a-result, specific x-rays were observed from elements more than l wt% contents in the spectral range of 3-8 keV, For analyzing liquid samples, laser pulses were focused on the surface of water jet stream or filter paper in which solution has soaked. Details of the results will be presented.

  1. An Alternative Method of Evaluating 1540NM Exposure Laser Damage using an Optical Tissue Phantom

    Jindra, Nichole M; Figueroa, Manuel A; Rockwell, Benjamin A; Chavey, Lucas J; Zohner, Justin J

    2006-01-01

    An optical phantom was designed to physically and optically resemble human tissue, in an effort to provide an alternative for detecting visual damage resulting from inadvertent exposure to infrared lasers...

  2. Short Pulsed Laser Methods for Velocimetry and Thermometry in High Enthalpy Facilities, Phase I

    National Aeronautics and Space Administration — A suite of laser-based diagnostics is proposed to measure velocity and temperature simultaneously using unseeded techniques in high enthalpy flows relevant to...

  3. Short Pulsed Laser Methods for Velocimetry and Thermometry in High Enthalpy Facilities, Phase II

    National Aeronautics and Space Administration — A suite of pulsed laser diagnostics is proposed for studying aspects of planetary entry and Earth atmospheric reentry in arc jets. For example, dissociation of...

  4. Laser applications in materials processing

    Ready, J.F.

    1980-01-01

    The seminar focused on laser annealing of semiconductors, laser processing of semiconductor devices and formation of coatings and powders, surface modification with lasers, and specialized laser processing methods. Papers were presented on the theoretical analysis of thermal and mass transport during laser annealing, applications of scanning continuous-wave and pulsed lasers in silicon technology, laser techniques in photovoltaic applications, and the synthesis of ceramic powders from laser-heated gas-phase reactants. Other papers included: reflectance changes of metals during laser irradiation, surface-alloying using high-power continuous lasers, laser growth of silicon ribbon, and commercial laser-shock processes

  5. Using Taguchi method to optimize welding pool of dissimilar laser welded components

    Anawa, E.; Olabi, Abdul-Ghani

    2008-01-01

    In the present work CO2 continuous laser welding process was successfully applied and optimized for joining a dissimilar AISI 316 stainless steel and AISI 1009 low carbon steel plates. Laser power, welding speed, and defocusing distance combinations were carefully selected with the objective of producing welded joint with complete penetration, minimum fusion zone size and acceptable welding profile. Fusion zone area and shape of dissimilar austenitic stainless steel with ferritic low carbon s...

  6. Review of the utilization of laser and electron beam methods in the nuclear domain

    Charissoux, C.; Bonnin, P.; Calvet, J.N.; Contre, M.

    1987-01-01

    The use of laser and electron beams by the nuclear industry for making components, fabricating fuels, waste processing, maintenance, and dismantling installations is reviewed. The advantages in welding include very rapid thermal cycles, deep weld zones with a restricted effect on surrounding material, and reduced residual stress. Surface treatments can also take advantage of these benefits. In cutting, the intrinsic advantages of the laser are completed by its high potential for robotization [fr

  7. Particle size determination of silver nanoparticles generated by plasma laser ablation using a deconvolution method

    Picciotto, A.; Torrisi, L.; Margarone, Daniele; Bellutti, P.

    2010-01-01

    Roč. 165, 6-10 (2010), s. 706-712 ISSN 1042-0150. [International Workshop on Pulsed Plasma Laser Ablation (PPLA)/4./. Monte Pieta, Messina, 18.06.2009-20.06.2009] Institutional research plan: CEZ:AV0Z10100522 Keywords : nanoparticles * plasma * laser ablation * surface plasmon resonance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.660, year: 2010

  8. Computational methods for describing the laser-induced mechanical response of tissue

    Trucano, T.; McGlaun, J.M.; Farnsworth, A.

    1994-02-01

    Detailed computational modeling of laser surgery requires treatment of the photoablation of human tissue by high intensity pulses of laser light and the subsequent thermomechanical response of the tissue. Three distinct physical regimes must be considered to accomplish this: (1) the immediate absorption of the laser pulse by the tissue and following tissue ablation, which is dependent upon tissue light absorption characteristics; (2) the near field thermal and mechanical response of the tissue to this laser pulse, and (3) the potential far field (and longer time) mechanical response of witness tissue. Both (2) and (3) are dependent upon accurate constitutive descriptions of the tissue. We will briefly review tissue absorptivity and mechanical behavior, with an emphasis on dynamic loads characteristic of the photoablation process. In this paper our focus will center on the requirements of numerical modeling and the uncertainties of mechanical tissue behavior under photoablation. We will also discuss potential contributions that computational simulations can make in the design of surgical protocols which utilize lasers, for example, in assessing the potential for collateral mechanical damage by laser pulses.

  9. Magneto-laser-ultrasonic therapy. Particular methodic of different diseases treatment. Scientific materials used in practice. V.4(2)

    Samosyuk, I.Z.; Chukhraev, N.V.; Myasnikov, V.G.; Samosyuk, N.I.

    2001-01-01

    Contemporary data about the use of magnetotherapy, ultrasound and magnetolaser therapy in resonance energy ranges are presented in this book. Practical methodics of simultaneous and combined use of these physical factors in different branches of clinical medicine (neurology, cardiology, gastroenterology and others) are described. Modern principles of the sensitive zone choice, bases of biorhythmic and resonance phenomena are presented. Practical uses of them became more and more important in physiotherapy and acupuncture. Diseases of different organs are considered, and magnetic, laser and ultrasound mehtods of their treatment are discussed. Special attention is paid to the use of magneto-laser and low-frequency ultrasonic therapy methods for diabetus melitus and respiratory organ treatment. Diseases of urinary tract, of ischemia, insult, ophthalmological ones and series of surgery profile diseases are considered in connection with different modern treatment methods of them. Review of cardiovascular, skin, digestive system diseases, those of ophtalmology, stomatology, otolaryngology nervous-psychic violations is presented and optimum methods of their treatment are recommended. The most part of magneto-laser-ultrasound therapy uses refers to the new generation of series 'MIT' and 'MIT-11' apparata which combine all three treatment factors

  10. Method for estimating optimal spectral and energy parameters of laser irradiation in photodynamic therapy of biological tissue

    Lisenko, S A; Kugeiko, M M [Belarusian State University, Minsk (Belarus)

    2015-04-30

    We have solved the problem of layer-by-layer laser-light dosimetry in biological tissues and of selecting an individual therapeutic dose in laser therapy. A method is proposed for real-time monitoring of the radiation density in tissue layers in vivo, concentrations of its endogenous (natural) and exogenous (specially administered) chromophores, as well as in-depth distributions of the spectrum of light action on these chromophores. As the background information use is made of the spectrum of diffuse light reflected from a patient's tissue, measured by a fibre-optic spectrophotometer. The measured spectrum is quantitatively analysed by the method of approximating functions for fluxes of light multiply scattered in tissue and by a semi-analytical method for calculating the in-depth distribution of the light flux in a multi-layered medium. We have shown the possibility of employing the developed method for monitoring photosensitizer and oxyhaemoglobin concentrations in tissue, light power absorbed by chromophores in tissue layers at different depths and laser-induced changes in the tissue morphology (vascular volume content and ratios of various forms of haemoglobin) during photodynamic therapy. (biophotonics)

  11. Corrosion resistance assessment of Co-Cr alloy frameworks fabricated by CAD/CAM milling, laser sintering, and casting methods.

    Tuna, Süleyman Hakan; Özçiçek Pekmez, Nuran; Kürkçüoğlu, Işin

    2015-11-01

    The effects of fabrication methods on the corrosion resistance of frameworks produced with Co-Cr alloys are not clear. The purpose of this in vitro study was to evaluate the electrochemical corrosion resistance of Co-Cr alloy specimens that were fabricated by conventional casting, milling, and laser sintering. The specimens fabricated with 3 different methods were investigated by potentiodynamic tests and electrochemical impedance spectroscopy in an artificial saliva. Ions released into the artificial saliva were estimated with inductively coupled plasma-mass spectrometry, and the results were statistically analyzed. The specimen surfaces were investigated with scanning electron microscopy before and after the tests. In terms of corrosion current and Rct properties, statistically significant differences were found both among the means of the methods and among the means of the material groups (Pcorrosion than those produced by milling and laser sintering. The corrosion resistance of a Co-Cr alloy specimens fabricated by milling or laser sintering was greater than that of the conventionally cast alloy specimens. The Co-Cr specimens produced by the same method also differed from one another in terms of corrosion resistance. These differences may be related to the variations in the alloy compositions. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  12. Experimentally studied laser fluorescence method for remote sensing of plant stress situation induced by improper plants watering

    Yu. V. Fedotov

    2014-01-01

    Full Text Available Stressful situations of plants can be caused by a lack of nutrients; mechanical damages; diseases; low or high temperatures; lack of illumination; insufficient or excess humidity of the soil; soil salinization; soil pollution by oil products or heavy metals; the increased acidity of the soil; use of pesticides, herbicides, insecticides, etc.At early stages it is often difficult to detect seemingly that the plants are in stressful situations caused by adverse external factors. However, the fluorescent analysis potentially allows detection of the stressful situations of plants by deformation of laser-induced fluorescence spectra. The paper conducts experimental investigations to learn the capabilities of the laser fluorescent method to monitor plant situations at 532nm wavelength of fluorescence excitation in the stressful situations induced by improper watering (at excess of moisture in the soil and at a lack of moisture.Researches of fluorescence spectra have been conducted using a created laboratory installation. As a source to excite fluorescence radiation the second harmonica of YAG:Nd laser is used. The subsystem to record fluorescence radiation is designed using a polychromator and a highly sensitive matrix detector with the amplifier of brightness.Experimental investigations have been conducted for fast-growing and unpretentious species of plants, namely different sorts of salad.Experimental studies of laser-induced fluorescence spectra of plants for 532nm excitement wavelength show that the impact of stressful factors on a plant due to the improper watering, significantly distorts a fluorescence spectrum of plants. Influence of a stressful factor can be shown as a changing profile of a fluorescence spectrum (an identifying factor, here, is a relationship of fluorescence intensities at two wavelengths, namely 685 nm and 740 nm or (and as a changing level of fluorescence that can be the basis for the laser method for monitoring the plant

  13. An improved method to experimentally determine temperature and pressure behind laser-induced shock waves at low Mach numbers

    Hendijanifard, Mohammad; Willis, David A

    2011-01-01

    Laser-matter interactions are frequently studied by measuring the propagation of shock waves caused by the rapid laser-induced material removal. An improved method for calculating the thermo-fluid parameters behind shock waves is introduced in this work. Shock waves in ambient air, induced by pulsed Nd : YAG laser ablation of aluminium films, are measured using a shadowgraph apparatus. Normal shock solutions are applied to experimental data for shock wave positions and used to calculate pressure, temperature, and velocity behind the shock wave. Non-dimensionalizing the pressure and temperature with respect to the ambient values, the dimensionless pressure and temperature are estimated to be as high as 90 and 16, respectively, at a time of 10 ns after the ablation pulse for a laser fluence of F = 14.5 J cm -2 . The results of the normal shock solution and the Taylor-Sedov similarity solution are compared to show that the Taylor-Sedov solution under-predicts pressure when the Mach number of the shock wave is small. At a fluence of 3.1 J cm -2 , the shock wave Mach number is less than 3, and the Taylor-Sedov solution under-predicts the non-dimensional pressure by as much as 45%.

  14. Amniotic membrane welded to contact lens by 1470-nm diode laser:a novel method for sutureless amniotic membrane transplantation

    Rifat Rasier

    2014-12-01

    Full Text Available AIM: To avoid the side effects of the suture usage by welding amniotic membrane (AM to contact lens (CL with laser.METHODS:AM was taken from pregnant women and cleaned from blood clots with sterile phosphate-buffered physiological saline solution which included antibiotics. Stromal side of the AM was spread inside of the CL and it was welded to CL by 1470 nm diode laser. 600 μm diameter fiber tip of the laser was contacted with the epithelial side of the AM from 4 separate points. After welding excess amniotic membrane around the CL was cut with a scalpel.RESULTS:Stromal side of the AM was spread inside of the CL and then with laser fiber, different power levels and exposure times were applied on the epithelium of AM and 340 mW for seven seconds was found optimal. CL and AM attached with the spot welding effect in 4 points by touching fiber tip. CL-AM welded complex did not separated from each other while holding AM that extend beyond the CL with the help of two forceps.CONCLUSION:As a conclusion, it was aimed in this study to achieve the success of the conventional amniotic membrane transplantation (AMTwith the easiness of applying a CL and to avoid risks and side effects of corneal or conjunctival suturing. The results showed that the application of the CL–AM complex will be as easy as the application of a CL and lasts shortly.

  15. Clustering and training set selection methods for improving the accuracy of quantitative laser induced breakdown spectroscopy

    Anderson, Ryan B., E-mail: randerson@astro.cornell.edu [Cornell University Department of Astronomy, 406 Space Sciences Building, Ithaca, NY 14853 (United States); Bell, James F., E-mail: Jim.Bell@asu.edu [Arizona State University School of Earth and Space Exploration, Bldg.: INTDS-A, Room: 115B, Box 871404, Tempe, AZ 85287 (United States); Wiens, Roger C., E-mail: rwiens@lanl.gov [Los Alamos National Laboratory, P.O. Box 1663 MS J565, Los Alamos, NM 87545 (United States); Morris, Richard V., E-mail: richard.v.morris@nasa.gov [NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX 77058 (United States); Clegg, Samuel M., E-mail: sclegg@lanl.gov [Los Alamos National Laboratory, P.O. Box 1663 MS J565, Los Alamos, NM 87545 (United States)

    2012-04-15

    We investigated five clustering and training set selection methods to improve the accuracy of quantitative chemical analysis of geologic samples by laser induced breakdown spectroscopy (LIBS) using partial least squares (PLS) regression. The LIBS spectra were previously acquired for 195 rock slabs and 31 pressed powder geostandards under 7 Torr CO{sub 2} at a stand-off distance of 7 m at 17 mJ per pulse to simulate the operational conditions of the ChemCam LIBS instrument on the Mars Science Laboratory Curiosity rover. The clustering and training set selection methods, which do not require prior knowledge of the chemical composition of the test-set samples, are based on grouping similar spectra and selecting appropriate training spectra for the partial least squares (PLS2) model. These methods were: (1) hierarchical clustering of the full set of training spectra and selection of a subset for use in training; (2) k-means clustering of all spectra and generation of PLS2 models based on the training samples within each cluster; (3) iterative use of PLS2 to predict sample composition and k-means clustering of the predicted compositions to subdivide the groups of spectra; (4) soft independent modeling of class analogy (SIMCA) classification of spectra, and generation of PLS2 models based on the training samples within each class; (5) use of Bayesian information criteria (BIC) to determine an optimal number of clusters and generation of PLS2 models based on the training samples within each cluster. The iterative method and the k-means method using 5 clusters showed the best performance, improving the absolute quadrature root mean squared error (RMSE) by {approx} 3 wt.%. The statistical significance of these improvements was {approx} 85%. Our results show that although clustering methods can modestly improve results, a large and diverse training set is the most reliable way to improve the accuracy of quantitative LIBS. In particular, additional sulfate standards and

  16. Numerical analysis of laser welding with consideration analytical methods of determining phase transformations and mechanical properties of welded joint

    Piekarska Wiesława

    2018-01-01

    Full Text Available The numerical analysis of laser welding process with consideration analytical methods determining phase transformations and mechanical properties of welded joints are presents in this paper. The analytical CCT diagram and final structural composition of S355 steel are presented. The empirical relations presents in paper are determined by chemical compositions investigated steel and cooling rate between temperatures 800-500°C (t8/5. Phase composition and mechanical properties each of structures of steel in weld and heat affected zone (HAZ are determined on the basis of analytical methods. Laser welded flat is used in numerical simulations in ABAQUS. Mathematical modes of volumetric welding source are used in the calculations. Temperature fields, shape and size of melting zone for selected points in the cross-section of the joint are determined on the basis of thermal cycles obtained numerical.

  17. Multivariate Methods for Prediction of Geologic Sample Composition with Laser-Induced Breakdown Spectroscopy

    Morris, Richard; Anderson, R.; Clegg, S. M.; Bell, J. F., III

    2010-01-01

    Laser-induced breakdown spectroscopy (LIBS) uses pulses of laser light to ablate a material from the surface of a sample and produce an expanding plasma. The optical emission from the plasma produces a spectrum which can be used to classify target materials and estimate their composition. The ChemCam instrument on the Mars Science Laboratory (MSL) mission will use LIBS to rapidly analyze targets remotely, allowing more resource- and time-intensive in-situ analyses to be reserved for targets of particular interest. ChemCam will also be used to analyze samples that are not reachable by the rover's in-situ instruments. Due to these tactical and scientific roles, it is important that ChemCam-derived sample compositions are as accurate as possible. We have compared the results of partial least squares (PLS), multilayer perceptron (MLP) artificial neural networks (ANNs), and cascade correlation (CC) ANNs to determine which technique yields better estimates of quantitative element abundances in rock and mineral samples. The number of hidden nodes in the MLP ANNs was optimized using a genetic algorithm. The influence of two data preprocessing techniques were also investigated: genetic algorithm feature selection and averaging the spectra for each training sample prior to training the PLS and ANN algorithms. We used a ChemCam-like laboratory stand-off LIBS system to collect spectra of 30 pressed powder geostandards and a diverse suite of 196 geologic slab samples of known bulk composition. We tested the performance of PLS and ANNs on a subset of these samples, choosing to focus on silicate rocks and minerals with a loss on ignition of less than 2 percent. This resulted in a set of 22 pressed powder geostandards and 80 geologic samples. Four of the geostandards were used as a validation set and 18 were used as the training set for the algorithms. We found that PLS typically resulted in the lowest average absolute error in its predictions, but that the optimized MLP ANN and

  18. [Study on Ammonia Emission Rules in a Dairy Feedlot Based on Laser Spectroscopy Detection Method].

    He, Ying; Zhang, Yu-jun; You, Kun; Wang, Li-ming; Gao, Yan-wei; Xu, Jin-feng; Gao, Zhi-ling; Ma, Wen-qi

    2016-03-01

    It needs on-line monitoring of ammonia concentration on dairy feedlot to disclose ammonia emissions characteristics accurately for reducing ammonia emissions and improving the ecological environment. The on-line monitoring system for ammonia concentration has been designed based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology combining with long open-path technology, then the study has been carried out with inverse dispersion technique and the system. The ammonia concentration in-situ has been detected and ammonia emission rules have been analyzed on a dairy feedlot in Baoding in autumn and winter of 2013. The monitoring indicated that the peak of ammonia concentration was 6.11 x 10(-6) in autumn, and that was 6.56 x 10(-6) in winter. The concentration results show that the variation of ammonia concentration had an obvious diurnal periodicity, and the general characteristic of diurnal variation was that the concentration was low in the daytime and was high at night. The ammonia emissions characteristic was obtained with inverse dispersion model that the peak of ammonia emissions velocity appeared at noon. The emission velocity was from 1.48 kg/head/hr to 130.6 kg/head/hr in autumn, and it was from 0.004 5 kg/head/hr to 43.32 kg/head/hr in winter which was lower than that in autumn. The results demonstrated ammonia emissions had certain seasonal differences in dairy feedlot scale. In conclusion, the ammonia concentration was detected with optical technology, and the ammonia emissions results were acquired by inverse dispersion model analysis with large range, high sensitivity, quick response without gas sampling. Thus, it's an effective method for ammonia emissions monitoring in dairy feedlot that provides technical support for scientific breeding.

  19. A novel laser-based method for controlled crystallization in dental prosthesis materials

    Cam, Peter; Neuenschwander, Beat; Schwaller, Patrick; Köhli, Benjamin; Lüscher, Beat; Senn, Florian; Kounga, Alain; Appert, Christoph

    2015-02-01

    Glass-ceramic materials are increasingly becoming the material of choice in the field of dental prosthetics, as they can feature both high strength and very good aesthetics. It is believed that their color, microstructure and mechanical properties can be tuned such as to achieve an optimal lifelike performance. In order to reach that ultimate perfection a controlled arrangement of amorphous and crystalline phases in the material is required. A phase transformation from amorphous to crystalline is achieved by a heat treatment at defined temperature levels. The traditional approach is to perform the heat treatment in a furnace. This, however, only allows a homogeneous degree of crystallization over the whole volume of the parent glass material. Here a novel approach using a local heat treatment by laser irradiation is presented. To investigate the potential of this approach the crystallization process of SiO2-Li2O-Al2O3-based glass has been studied with laser systems (pulsed and continuous wave) operating at different wavelengths. Our results show the feasibility of gradual and partial crystallization of the base material using continuous laser irradiation. A dental prosthesis machined from an amorphous glassy state can be effectively treated with laser irradiation and crystallized within a confined region of a few millimeters starting from the body surface. Very good aesthetics have been achieved. Preliminary investigation with pulsed nanosecond lasers of a few hundreds nanoseconds pulse width has enabled more refinement of crystallization and possibility to place start of phase change within the material bulk.

  20. The Use of Laser Microdissection in Forensic Sexual Assault Casework: Pros and Cons Compared to Standard Methods.

    Costa, Sergio; Correia-de-Sá, Paulo; Porto, Maria J; Cainé, Laura

    2017-07-01

    Sexual assault samples are among the most frequently analyzed in a forensic laboratory. These account for almost half of all samples processed routinely, and a large portion of these cases remain unsolved. These samples often pose problems to traditional analytic methods of identification because they consist most frequently of cell mixtures from at least two contributors: the victim (usually female) and the perpetrator (usually male). In this study, we propose the use of current preliminary testing for sperm detection in order to determine the chances of success when faced with samples which can be good candidates to undergo analysis with the laser microdissection technology. Also, we used laser microdissection technology to capture fluorescently stained cells of interest differentiated by gender. Collected materials were then used for DNA genotyping with commercially available amplification kits such as Minifiler, Identifiler Plus, NGM, and Y-Filer. Both the methodology and the quality of the results were evaluated to assess the pros and cons of laser microdissection compared with standard methods. Overall, the combination of fluorescent staining combined with the Minifiler amplification kit provided the best results for autosomal markers, whereas the Y-Filer kit returned the expected results regardless of the used method. © 2017 American Academy of Forensic Sciences.

  1. Laser microsampling method for determination of retained fission gas in irradiated nuclear fuels

    Graczyk, D.G.; Bandyopadhyay, G.; Gehl, S.M.; Hughes, J.P.; Goodspeed, H.T.

    1979-10-01

    A small ruby laser adapted to fire through a microscope is used to release fission gases from specific sites on a plane surface of an irradiated fuel specimen. Interaction of the focused laser pulse with the specimen surface results in a conical crater from which sampled material has been vaporized; the crater is surrounded by a heat-affected zone in which intergranular fracture and grain separation allow release of grain-boundary gases. Procedures for measuring the amount of krypton-85 released by laser heating and the volume of material from which the release occurred are presented. The data obtained may be used to obtain local krypton fission-gas concentrations and the intragranular/intergranular distribution

  2. Comparison of 2 root surface area measurement methods: 3-dimensional laser scanning and cone-beam computed tomography

    Tasanapanont, Jintana; Apisariyakul, Janya; Wattanachai, Tanapan; Jotikasthira, Dhirawat; Sriwilas, Patiyut; Midtboe, Marit

    2017-01-01

    The aim of this study was to compare the use of 3-dimensional (3D) laser scanning and cone-beam computed tomography (CBCT) as methods of root surface measurement. Thirty teeth (15 maxillary first premolars and 15 mandibular first premolars) from 8 patients who required extractions for orthodontic treatment were selected. Before extraction, pre-treatment CBCT images of all the patients were recorded. First, a CBCT image was imported into simulation software (Mimics version 15.01; Materialise, Leuven, Belgium) and the root surface area of each tooth was calculated using 3-Matic (version 7.01, Materialise, Leuven, Belgium). After extraction, all the teeth were scanned and the root surface area of each extracted tooth was calculated. The root surface areas calculated using these 2 measurement methods were analyzed using the paired t-test (P<.05). Correlations between the 2 methods were determined by calculating the Pearson correlation coefficient. The intraclass correlation coefficient (ICC) was used to assess intraobserver reliability. The root surface area measurements (230.11±41.97 mm"2) obtained using CBCT were slightly greater than those (229.31±42.46 mm2) obtained using 3D laser scanning, but not significantly (P=.425). A high Pearson correlation coefficient was found between the CBCT and the 3D laser scanner measurements. The intraobserver ICC was 1.000 for 3D laser scanning and 0.990 for CBCT. This study presents a novel CBCT approach for measuring the root surface area; this technique can be used for estimating the root surface area of non-extracted teeth

  3. The repeatability of three diagnostic methods (visual using ICDAS II, laser fluorescence, and radiographic) for early caries detection

    Sukmasari, S.; Lestari, W.; Ko, B. B.; Noh, Z.; Asmail, N.; Yaacob, N.

    2017-08-01

    Newly introduced ICDAS II as a visual method, laser fluorescence as another technique that have ability to quantify early mineral loss of tooth structure and intra oral radiograph, are methods can be used in the clinic. To provide standardization for comprehensive caries management at an early stage, all methods supposed to be tested between users. The objective of this research is to evaluate the repeatability of each system. It is a comparative cross sectional study using 100 extracted permanent teeth without obvious cavitation (premolar & molar) that were collected and stored in thymol solution. The teeth were embedded on the wax block and labeled with numbers. All 5 surfaces were examined by 5 examiners using visual (ICDAS II), laser fluorescence (LF) and radiographic examination. The data were then analyzed to measure intra and inter examiner repeatability using Cronbach’s alpha and inter-item correlation matrix. Intra-examiner repeatability for all examiners was >0.7. Chronbach’s a value for inter-examiner repeatability for ICDAS II was >0.8 on 3 surfaces except on buccal and lingual. LF exhibit repeatability of >0.8 on all surfaces. Radiograph shows a low value of inter examiner repeatability (students for inter-item correlation while the 2nd and 3rd reading of LF displays the best agreement. ICDAS II score favors more non-invasive treatment compared to LF. ICDAS II showed good repeatability except on buccal and lingual surfaces. In line with some of the previous study, ICDAS II is applicable for caries detection in daily clinical basis. Laser fluorescence exhibits the highest repeatability while the radiograph showed weak inter-examiner repeatability. Treatment decisions of ICDAS II propose more preventive treatment for early caries lesions compared to laser fluorescence.

  4. Comparison of 2 root surface area measurement methods: 3-dimensional laser scanning and cone-beam computed tomography

    Tasanapanont, Jintana; Apisariyakul, Janya; Wattanachai, Tanapan; Jotikasthira, Dhirawat [Dept. of Orthodontics and Pediatric Dentistry, Faculty of Dentistry, Chiang Mai University, Chiang Mai (Thailand); Sriwilas, Patiyut [Dept. of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok (Thailand); Midtboe, Marit [Dept. of Clinical Dentistry - Orthodontics, Faculty of Medicine and Dentistry, University of Bergen, Bergen (Norway)

    2017-06-15

    The aim of this study was to compare the use of 3-dimensional (3D) laser scanning and cone-beam computed tomography (CBCT) as methods of root surface measurement. Thirty teeth (15 maxillary first premolars and 15 mandibular first premolars) from 8 patients who required extractions for orthodontic treatment were selected. Before extraction, pre-treatment CBCT images of all the patients were recorded. First, a CBCT image was imported into simulation software (Mimics version 15.01; Materialise, Leuven, Belgium) and the root surface area of each tooth was calculated using 3-Matic (version 7.01, Materialise, Leuven, Belgium). After extraction, all the teeth were scanned and the root surface area of each extracted tooth was calculated. The root surface areas calculated using these 2 measurement methods were analyzed using the paired t-test (P<.05). Correlations between the 2 methods were determined by calculating the Pearson correlation coefficient. The intraclass correlation coefficient (ICC) was used to assess intraobserver reliability. The root surface area measurements (230.11±41.97 mm{sup 2}) obtained using CBCT were slightly greater than those (229.31±42.46 mm2) obtained using 3D laser scanning, but not significantly (P=.425). A high Pearson correlation coefficient was found between the CBCT and the 3D laser scanner measurements. The intraobserver ICC was 1.000 for 3D laser scanning and 0.990 for CBCT. This study presents a novel CBCT approach for measuring the root surface area; this technique can be used for estimating the root surface area of non-extracted teeth.

  5. Method for selecting hollow microspheres for use in laser fusion targets

    Farnum, Eugene H.; Fries, R. Jay; Havenhill, Jerry W.; Smith, Maurice Lee; Stoltz, Daniel L.

    1976-01-01

    Hollow microspheres having thin and very uniform wall thickness are useful as containers for the deuterium and tritium gas mixture used as a fuel in laser fusion targets. Hollow microspheres are commercially available; however, in commercial lots only a very small number meet the rigid requirements for use in laser fusion targets. Those meeting these requirements may be separated from the unsuitable ones by subjecting the commercial lot to size and density separations and then by subjecting those hollow microspheres thus separated to an external pressurization at which those which are aspherical or which have nonuniform walls are broken and separating the sound hollow microspheres from the broken ones.

  6. Analysis of laser and inkjet prints using spectroscopic methods for forensic identification of questioned documents

    Gál, Lukáš; Belovičová, Michaela; Oravec, Michal; Palková, Miroslava; Čeppan, Michal

    2013-01-01

    The spectral properties in UV-VIS-NIR and IR regions of laser and inkjet prints were studied for the purposes of forensic analysis of documents. The procedures of measurements and processing of spectra of printed documents using fibre optics reflectance spectroscopy in UV-VIS and NIR region, FTIR-ATR with diamond/ZnSe and germanium crystals were optimized. It was found that the shapes of spectra of various black laser jet prints and inkjet prints generally differ in the spectral regions...

  7. New method for laser driven ion acceleration with isolated, mass-limited targets

    Paasch-Colberg, T.; Sokollik, T.; Gorling, K.; Eichmann, U.; Steinke, S.; Schnuerer, M.; Nickles, P.V.; Andreev, A.; Sandner, W.

    2011-01-01

    A new technique to investigate laser driven ion acceleration with fully isolated, mass-limited glass spheres with a diameter down to 8μm is presented. A Paul trap was used to prepare a levitating glass sphere for the interaction with a laser pulse of relativistic intensity. Narrow-bandwidth energy spectra of protons and oxygen ions have been observed and were attributed to specific acceleration field dynamics in case of the spherical target geometry. A general limiting mechanism has been found that explains the experimentally observed ion energies for the mass-limited target.

  8. Method for measuring energy-input inhomogeneities in electroionization CO/sub 2/-lasers

    Borovkov, V V; Kornilov, V G; Sukhanov, L V; Chelpanov, V I

    1987-08-01

    A Michelson interferometer at a wavelength of 0.63 micron was used to measure optical inhomogeneities due to variations of the polarizability of the molecular components in CO/sub 2/-laser mixtures under vibrational excitation in a nonself-sustained electric discharge. It is suggested that the observed effect can be used for the noninertial and noncontact diagnostics of energy-input distribution over the cross section of the active medium of an electroionization CO/sub 2/-laser. Results are presented for N/sub 2/-He, CO/sub 2/-He, CO/sub 2/-N/sub 2/-He, and CO/sub 2/-He mixtures. 10 references.

  9. Experimental Research of Reliability of Plant Stress State Detection by Laser-Induced Fluorescence Method

    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.

  10. Characterization of ultra-fast deposited polycrystalline graphite by a CO{sub 2} laser-assisted combustion-flame method

    McKindra, Travis, E-mail: mckindra@mst.edu [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Patil, Sandeep; O' Keefe, Matthew J. [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Han Yaoxuan; Ling Hao; Lu Yongfeng [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States)

    2009-02-15

    High deposition rate, 750 {mu}m/min, crystalline graphite was deposited on WC substrates by a CO{sub 2} laser-assisted combustion-flame method at laser powers between 300 and 800 W. The structures, which were identified as pillars, were characterized by various methods. The pillars were cylindrical in shape and grew to a size of approximately 3 mm in length and in a few minutes. The laser power did not affect the overall length of the pillar, but caused changes in the physical shape. X-ray and electron diffraction results revealed the pillars to be crystalline graphite regardless of the laser power. Investigation of the pillars by scanning electron microscopy showed two distinct microstructural areas: an inner core of dense material surrounded by an outer shell of lamellar-like material. The core/shell microstructure was unaffected by the level of CO{sub 2} laser power.

  11. Measurement of particle size distribution of soil and selected aggregate sizes using the hydrometer method and laser diffractometry

    Guzmán, G.; Gómez, J. A.; Giráldez, J. V.

    2010-05-01

    Soil particle size distribution has been traditionally determined by the hydrometer or the sieve-pipette methods, both of them time consuming and requiring a relatively large soil sample. This might be a limitation in situations, such as for instance analysis of suspended sediment, when the sample is small. A possible alternative to these methods are the optical techniques such as laser diffractometry. However the literature indicates that the use of this technique as an alternative to traditional methods is still limited, because the difficulty in replicating the results obtained with the standard methods. In this study we present the percentages of soil grain size determined using laser diffractometry within ranges set between 0.04 - 2000 μm. A Beckman-Coulter ® LS-230 with a 750 nm laser beam and software version 3.2 in five soils, representative of southern Spain: Alameda, Benacazón, Conchuela, Lanjarón and Pedrera. In three of the studied soils (Alameda, Benacazón and Conchuela) the particle size distribution of each aggregate size class was also determined. Aggregate size classes were obtained by dry sieve analysis using a Retsch AS 200 basic ®. Two hundred grams of air dried soil were sieved during 150 s, at amplitude 2 mm, getting nine different sizes between 2000 μm and 10 μm. Analyses were performed by triplicate. The soil sample preparation was also adapted to our conditions. A small amount each soil sample (less than 1 g) was transferred to the fluid module full of running water and disaggregated by ultrasonication at energy level 4 and 80 ml of sodium hexametaphosphate solution during 580 seconds. Two replicates of each sample were performed. Each measurement was made for a 90 second reading at a pump speed of 62. After the laser diffractometry analysis, each soil and its aggregate classes were processed calibrating its own optical model fitting the optical parameters that mainly depends on the color and the shape of the analyzed particle. As a

  12. Lateral Temperature-Gradient Method for High-Throughput Characterization of Material Processing by Millisecond Laser Annealing.

    Bell, Robert T; Jacobs, Alan G; Sorg, Victoria C; Jung, Byungki; Hill, Megan O; Treml, Benjamin E; Thompson, Michael O

    2016-09-12

    A high-throughput method for characterizing the temperature dependence of material properties following microsecond to millisecond thermal annealing, exploiting the temperature gradients created by a lateral gradient laser spike anneal (lgLSA), is presented. Laser scans generate spatial thermal gradients of up to 5 °C/μm with peak temperatures ranging from ambient to in excess of 1400 °C, limited only by laser power and materials thermal limits. Discrete spatial property measurements across the temperature gradient are then equivalent to independent measurements after varying temperature anneals. Accurate temperature calibrations, essential to quantitative analysis, are critical and methods for both peak temperature and spatial/temporal temperature profile characterization are presented. These include absolute temperature calibrations based on melting and thermal decomposition, and time-resolved profiles measured using platinum thermistors. A variety of spatially resolved measurement probes, ranging from point-like continuous profiling to large area sampling, are discussed. Examples from annealing of III-V semiconductors, CdSe quantum dots, low-κ dielectrics, and block copolymers are included to demonstrate the flexibility, high throughput, and precision of this technique.

  13. A novel method for soil aggregate stability measurement by laser granulometry with sonication

    Rawlins, B. G.; Lark, R. M.; Wragg, J.

    2012-04-01

    Regulatory authorities need to establish rapid, cost-effective methods to measure soil physical indicators - such as aggregate stability - which can be applied to large numbers of soil samples to detect changes of soil quality through monitoring. Limitations of sieve-based methods to measure the stability of soil macro-aggregates include: i) the mass of stable aggregates is measured, only for a few, discrete sieve/size fractions, ii) no account is taken of the fundamental particle size distribution of the sub-sampled material, and iii) they are labour intensive. These limitations could be overcome by measurements with a Laser Granulometer (LG) instrument, but this technology has not been widely applied to the quantification of aggregate stability of soils. We present a novel method to quantify macro-aggregate (1-2 mm) stability. We measure the difference between the mean weight diameter (MWD; μm) of aggregates that are stable in circulating water of low ionic strength, and the MWD of the fundamental particles of the soil to which these aggregates are reduced by sonication. The suspension is circulated rapidly through a LG analytical cell from a connected vessel for ten seconds; during this period hydrodynamic forces associated with the circulating water lead to the destruction of unstable aggregates. The MWD of stable aggregates is then measured by LG. In the next step, the aggregates - which are kept in the vessel at a minimal water circulation speed - are subject to sonication (18W for ten minutes) so the vast majority of the sample is broken down into its fundamental particles. The suspension is then recirculated rapidly through the LG and the MWD measured again. We refer to the difference between these two measurements as disaggregation reduction (DR) - the reduction in MWD on disaggregation by sonication. Soil types with more stable aggregates have larger values of DR. The stable aggregates - which are resistant to both slaking and mechanical breakdown by the

  14. Theoretical study of annealed proton-exchanged Nd $LiNbO_{3}$ channel waveguide lasers with variational method

    De Long Zhang; Yuan Guo Xie; Guilan, Ding; Yuming, Cui; Cai He Chen

    2001-01-01

    The controllable fabrication parameters, including anneal time, initial exchange time, channel width, dependences of TM/sub 00/ mode size, corresponding effective refractive index, effective pump area, and coupling efficiency between pump and laser modes in z-cut annealed proton-exchanged (APE) Nd:LiNbO/sub 3/ channel waveguide lasers were studied by using variational method. The effect of channel width on the surface index increment and the waveguide depth was taken into account. The features of mode size and effective refractive index were summarized, discussed, and compared with previously published experimental results. The effective pump area, which is directly proportional to threshold pump power, increases strongly, slightly, and very slightly with the increase of anneal time, channel width, and initial exchange time, respectively. However, the coupling efficiency, which is directly proportional to slope efficiency, remains constant (around 0.82) no matter what changes made to these parameters. The var...

  15. Examination of structure and mechanical properties of hard-to-weld metal joints obtained with the laser method

    Czujko, T.; Przetakiewicz, W.; Jozwiak, S.; Hoffman, J.; Kalita, W.

    1995-01-01

    Metal joints of stainless of type X6CrNiMoTi1722 (according to DIN) and high conductivity (HC) copper, and joints of transformer steel containing about 3.5% of silicon were obtained using metal sheets 2 mm in thickness. The microstructure and the distribution of microhardness in the area of the joint, and the changes of the strength and elongation caused by the process of laser welding were examined with reference to the properties of the native metal; and, in the case of transformer steel-joints, the effects of welding by means of the TIG method were also analyzed. A probable mechanism of the formation of the steel-copper joint was presented, the strength of which is comparable with that of copper. The superiority of laser welding over TIG welding was also demonstrated. (author). 11 refs, 4 figs, 1 tab

  16. Laser ablation method for cleaning of mirror surfaces for optical diagnostic systems at the ITER

    Aleksandrova, A.S.; Kuznetsov, A.P.; Gubskij, K.L.; Petrovskij, V.N.; Savelov, A.S.; Shtamm, V.G.; Buzhinskij, O.I.

    2012-01-01

    The possibility of cleaning metallic mirrors from films with complex composition by pulsed radiation from a fiber laser has been experimentally examined. It has been shown that the high initial reflection characteristics of optical elements can be recovered by choosing regimes of the action of radiation on the surface with a deposited film [ru

  17. Time dependent growth of vertically aligned carbon nanotube forest using a laser activated catalytical CVD method

    Haluska, M.; Bellouard, Y.J.; Dietzel, A.H.

    2008-01-01

    We report the growth of vertically aligned single-wall and multi-wall carbon nanotube forest using a Laser Activated - Catalytic Chemical Vapor Deposition process. The experiments were performed in a cold-wall reactor filled with an ethylene-hydrogen-argon gas mixture in a 5:2:8 ratio at ambient

  18. Carbohydrate-protein interaction studies by laser photo CIDNP NMR methods

    Siebert, HC; Kaptein, R; Beintema, JJ; Soedjanaatmadja, UM; Wright, CS; Rice, A; Kleineidam, RG; Kruse, S; Schauer, R; Pouwels, PJW; Kamerling, JP; Gabius, HJ; Vliegenthart, JFG

    The side chains of tyrosine, tryptophan and histidine are able to produce CIDNP (Chemically Induced Dynamic Nuclear Polarization) signals after laser irradiation in the presence of a suitable radical pair-generating dye. Elicitation of such a response in proteins implies surface accessibility of the

  19. Method to separate various isotopes in compounds by means of laser radiation

    Meyer-Kretschmer, G.; Jetter, H.; Toennies, P.

    1980-01-01

    The uranium hexafluoride together with an inert addition gas is cooled down below 50 K by adiabatic expansion, then the state of oscillation of the molecules is changed specifically for each isotope using laser light, and subsequently positive ions are produced by means of an electron beam. The ions are removed from the gas by means of an electric field. (DG) [de

  20. Theoretical investigation of dielectric corona pre-ionization TEA nitrogen laser based on transmission line method

    Bahrampour, Alireza; Fallah, Robabeh; Ganjovi, Alireza A.; Bahrampour, Abolfazl

    2007-07-01

    This paper models the dielectric corona pre-ionization, capacitor transfer type of flat-plane transmission line traveling wave transverse excited atmospheric pressure nitrogen laser by a non-linear lumped RLC electric circuit. The flat-plane transmission line and the pre-ionizer dielectric are modeled by a lumped linear RLC and time-dependent non-linear RC circuit, respectively. The main discharge region is considered as a time-dependent non-linear RLC circuit where its resistance value is also depends on the radiated pre-ionization ultra violet (UV) intensity. The UV radiation is radiated by the resistance due to the surface plasma on the pre-ionizer dielectric. The theoretical predictions are in a very good agreement with the experimental observations. The electric circuit equations (including the ionization rate equations), the equations of laser levels population densities and propagation equation of laser intensities, are solved numerically. As a result, the effects of pre-ionizer dielectric parameters on the electrical behavior and output laser intensity are obtained.

  1. In vitro evaluation of microleakage around orthodontic brackets using laser etching and Acid etching methods.

    Mohammad Hossein Toodehzaeim

    2014-06-01

    Full Text Available path of microleakage between the enamel and adhesive potentially allows microbial ingress that may consequently cause enamel decalcification. The aim of this study was to compare microleakage of brackets bonded either by laser or acid etching techniques.The specimens were 33 extracted premolars that were divided into three groups as the acid etching group (group 1, laser etching with Er:YAG at 100 mJ and 15 Hz for 15s (group 2, and laser etching with Er:YAG at 140 mJ and 15 Hz for 15s (group 3. After photo polymerization, the teeth were subjected to 500 thermal cycles. Then the specimens were sealed with nail varnish, stained with 2% methylen blue for 24hs, sectioned, and examined under a stereomicroscope. They were scored for marginal microleakage that occurred between the adhesive-enamel and bracket-adhesive interfaces from the occlusal and gingival margins. Data were analyzed with the Kruskal- Wallis test.For the adhesive-enamel and bracket-adhesive surfaces, significant differences were not observed between the three groups.According to this study, the Er:YAG laser with 1.5 and 2.1 watt settings may be used as an adjunctive for preparing the surface for orthodontic bracket bonding.

  2. Rapid identification of pathogens directly from blood culture bottles by Bruker matrix-assisted laser desorption laser ionization-time of flight mass spectrometry versus routine methods.

    Jamal, Wafaa; Saleem, Rola; Rotimi, Vincent O

    2013-08-01

    The use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of microorganisms directly from blood culture is an exciting dimension to the microbiologists. We evaluated the performance of Bruker SepsiTyper kit™ (STK) for direct identification of bacteria from positive blood culture. This was done in parallel with conventional methods. Nonrepetitive positive blood cultures from 160 consecutive patients were prospectively evaluated by both methods. Of 160 positive blood cultures, the STK identified 114 (75.6%) isolates and routine conventional method 150 (93%). Thirty-six isolates were misidentified or not identified by the kit. Of these, 5 had score of >2.000 and 31 had an unreliable low score of <1.7. Four of 8 yeasts were identified correctly. The average turnaround time using the STK was 35 min, including extraction steps and 30:12 to 36:12 h with routine method. The STK holds promise for timely management of bacteremic patients. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Studying stellar binary systems with the Laser Interferometer Space Antenna using delayed rejection Markov chain Monte Carlo methods

    Trias, Miquel; Vecchio, Alberto; Veitch, John

    2009-01-01

    Bayesian analysis of Laser Interferometer Space Antenna (LISA) data sets based on Markov chain Monte Carlo methods has been shown to be a challenging problem, in part due to the complicated structure of the likelihood function consisting of several isolated local maxima that dramatically reduces the efficiency of the sampling techniques. Here we introduce a new fully Markovian algorithm, a delayed rejection Metropolis-Hastings Markov chain Monte Carlo method, to efficiently explore these kind of structures and we demonstrate its performance on selected LISA data sets containing a known number of stellar-mass binary signals embedded in Gaussian stationary noise.

  4. The research of PSD location method in micro laser welding fields

    Zhang, Qiue; Zhang, Rong; Dong, Hua

    2010-11-01

    In the field of micro laser welding, besides the special requirement in the parameter of lasers, the locating in welding points accurately is very important. The article adopt position sensitive detector (PSD) as hard core, combine optic system, electric circuits and PC and software processing, confirm the location of welding points. The signal detection circuits adopt the special integrate circuit H-2476 to process weak signal. It is an integrated circuit for high-speed, high-sensitivity optical range finding, which has stronger noiseproof feature, combine digital filter arithmetic, carry out repair the any non-ideal factors, increasing the measure precision. The amplifier adopt programmable amplifier LTC6915. The system adapt two dimension stepping motor drive the workbench, computer and corresponding software processing, make sure the location of spot weld. According to different workpieces to design the clamps. The system on-line detect PSD 's output signal in the moving processing. At the workbench moves in the X direction, the filaments offset is detected dynamic. Analyze the X axes moving sampling signal direction could be estimate the Y axes moving direction, and regulate the Y axes moving values. The workbench driver adopt A3979, it is a stepping motor driver with insert transducer and operate easily. It adapts the requirement of location in micro laser welding fields, real-time control to adjust by computer. It can be content up 20 μm's laser micro welding requirement on the whole. Using laser powder cladding technology achieve inter-penetration welding of high quality and reliability.

  5. Novel method to ascertain chromatin accessibility at specific genomic loci from frozen brain homogenates and laser capture microdissected defined cells.

    Delvaux, Elaine; Mastroeni, Diego; Nolz, Jennifer; Coleman, Paul D

    2016-06-01

    We describe a novel method for assessing the "open" or "closed" state of chromatin at selected locations within the genome. This method combines the use of Benzonase, which can digest DNA in the presence of actin, with qPCR to define digested regions. We demonstrate the application of this method in brain homogenates and laser captured cells. We also demonstrate application to selected sites within more than one gene and multiple sites within one gene. We demonstrate the validity of the method by treating cells with valproate, known to render chromatin more permissive, and by comparison with classical digestion with DNase I in an in vitro preparation. Although we demonstrate the use of this method in brain tissue we also recognize its applicability to other tissue types.

  6. Novel method to ascertain chromatin accessibility at specific genomic loci from frozen brain homogenates and laser capture microdissected defined cells

    Elaine Delvaux

    2016-06-01

    Full Text Available We describe a novel method for assessing the “open” or “closed” state of chromatin at selected locations within the genome. This method combines the use of Benzonase, which can digest DNA in the presence of actin, with quantitative polymerase chain reaction to define digested regions. We demonstrate the application of this method in brain homogenates and laser captured cells. We also demonstrate application to selected sites within more than 1 gene and multiple sites within 1 gene. We demonstrate the validity of the method by treating cells with valproate, known to render chromatin more permissive, and by comparison with classical digestion with DNase I in an in vitro preparation. Although we demonstrate the use of this method in brain tissue, we also recognize its applicability to other tissue types.

  7. Selective ablation of Copper-Indium-Diselenide solar cells monitored by laser-induced breakdown spectroscopy and classification methods

    Diego-Vallejo, David [Technische Universität Berlin, Institute of Optics and Atomic Physics, Straße des 17, Juni 135, 10623 Berlin (Germany); Laser- und Medizin- Technologie Berlin GmbH (LMTB), Applied Laser Technology, Fabeckstr. 60-62, 14195 Berlin (Germany); Ashkenasi, David, E-mail: d.ashkenasi@lmtb.de [Laser- und Medizin- Technologie Berlin GmbH (LMTB), Applied Laser Technology, Fabeckstr. 60-62, 14195 Berlin (Germany); Lemke, Andreas [Laser- und Medizin- Technologie Berlin GmbH (LMTB), Applied Laser Technology, Fabeckstr. 60-62, 14195 Berlin (Germany); Eichler, Hans Joachim [Technische Universität Berlin, Institute of Optics and Atomic Physics, Straße des 17, Juni 135, 10623 Berlin (Germany); Laser- und Medizin- Technologie Berlin GmbH (LMTB), Applied Laser Technology, Fabeckstr. 60-62, 14195 Berlin (Germany)

    2013-09-01

    Laser-induced breakdown spectroscopy (LIBS) and two classification methods, i.e. linear correlation and artificial neural networks (ANN), are used to monitor P1, P2 and P3 scribing steps of Copper-Indium-Diselenide (CIS) solar cells. Narrow channels featuring complete removal of desired layers with minimum damage on the underlying film are expected to enhance efficiency of solar cells. The monitoring technique is intended to determine that enough material has been removed to reach the desired layer based on the analysis of plasma emission acquired during multiple pass laser scribing. When successful selective scribing is achieved, a high degree of similarity between test and reference spectra has to be identified by classification methods in order to stop the scribing procedure and avoid damaging the bottom layer. Performance of linear correlation and artificial neural networks is compared and evaluated for two spectral bandwidths. By using experimentally determined combinations of classifier and analyzed spectral band for each step, classification performance achieves errors of 7, 1 and 4% for steps P1, P2 and P3, respectively. The feasibility of using plasma emission for the supervision of processing steps of solar cell manufacturing is demonstrated. This method has the potential to be implemented as an online monitoring procedure assisting the production of solar cells. - Highlights: • LIBS and two classification methods were used to monitor CIS solar cells processing. • Selective ablation of thin-film solar cells was improved with inspection system. • Customized classification method and analyzed spectral band enhanced performance.

  8. Comparison of some effects of modification of a polylactide surface layer by chemical, plasma, and laser methods

    Moraczewski, Krzysztof; Rytlewski, Piotr; Malinowski, Rafał; Żenkiewicz, Marian

    2015-08-01

    The article presents the results of studies and comparison of selected properties of the modified PLA surface layer. The modification was carried out with three methods. In the chemical method, a 0.25 M solution of sodium hydroxide in water and ethanol was utilized. In the plasma method, a 50 W generator was used, which produced plasma in the air atmosphere under reduced pressure. In the laser method, a pulsed ArF excimer laser with fluency of 60 mJ/cm2 was applied. Polylactide samples were examined by using the following techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and X-ray photoelectron spectroscopy (XPS). Images of surfaces of the modified samples were recorded, contact angles were measured, and surface free energy was calculated. Qualitative and quantitative analyses of chemical composition of the PLA surface layer were performed as well. Based on the survey it was found that the best modification results are obtained using the plasma method.

  9. Influence of femtosecond laser marking on the corrosion resistance of stainless steels

    Valette, S.; Steyer, P.; Richard, L.; Forest, B.; Donnet, C.; Audouard, E.

    2006-01-01

    Marking is of prime importance in the field of biomaterials to allow the identification of surgical tools as well as prostheses. Nowadays, marking is often achieved by means of laser beam, which may modify the characteristics of the treated surfaces. The use of laser devices delivering nanosecond pulses is known to induce dramatic corrosion degradations during sterilization or decontamination processes of the biomaterials. The aim of the present study is to investigate the ability of femtosecond (pulse duration in the 10 -15 s range) laser treatments to avoid preferential corrosion processes of the marked areas, in order to extend the durability and the reliability of biomaterials. Experiments have been performed on martensitic Z30C13 and austenitic 316L stainless steels. Electrochemical measurements (cyclic polarization curves) were carried out to determine the passive state of samples before and after engraving, their corrosion rate and their susceptibility to localized corrosion. Further protracted immersion tests were also carried out to evaluate the natural long-term degradation of engraved parts. The electrochemical behavior is then explained on the basis of surface characterizations. Femtosecond laser marking is shown to provide an electrochemical ennoblement. Moreover, the chemical composition is not affected so that the passive character of both stainless steels is maintained, even improved if we consider the susceptibility to localized corrosion

  10. Laser-induced micro-thermography - an innovative method of nondestructive testing of coatings. Laserinduzierte Mikrothermographie - ein innovatives ZfP-Verfahren zur Pruefung von Beschichtungen

    Radtke, U; Crostack, H A; Peppler, P; Winschuh, E

    1992-01-01

    The described, innovative NDT method of the laser-induced thermowave analysis, also called laser-induced microthermography, permits the 3D imaging of thermal characteristics with high axial and lateral resolution. The results show that the method is suitable for the quality control of coatings and yields information on thickness, thermal homogeneity and adhesion as well as valuable additional information, as compared to conventional metallography. (orig.)

  11. Calculus migration characterization during Ho:YAG laser lithotripsy by high-speed camera using suspended pendulum method.

    Zhang, Jian James; Rajabhandharaks, Danop; Xuan, Jason Rongwei; Chia, Ray W J; Hasenberg, Thomas

    2017-07-01

    Calculus migration is a common problem during ureteroscopic laser lithotripsy procedure to treat urolithiasis. A conventional experimental method to characterize calculus migration utilized a hosting container (e.g., a "V" grove or a test tube). These methods, however, demonstrated large variation and poor detectability, possibly attributed to the friction between the calculus and the container on which the calculus was situated. In this study, calculus migration was investigated using a pendulum model suspended underwater to eliminate the aforementioned friction. A high-speed camera was used to study the movement of the calculus which covered zero order (displacement), first order (speed), and second order (acceleration). A commercialized, pulsed Ho:YAG laser at 2.1 μm, a 365-μm core diameter fiber, and a calculus phantom (Plaster of Paris, 10 × 10 × 10 mm 3 ) was utilized to mimic laser lithotripsy procedure. The phantom was hung on a stainless steel bar and irradiated by the laser at 0.5, 1.0, and 1.5 J energy per pulse at 10 Hz for 1 s (i.e., 5, 10, and 15 W). Movement of the phantom was recorded by a high-speed camera with a frame rate of 10,000 FPS. The video data files are analyzed by MATLAB program by processing each image frame and obtaining position data of the calculus. With a sample size of 10, the maximum displacement was 1.25 ± 0.10, 3.01 ± 0.52, and 4.37 ± 0.58 mm for 0.5, 1, and 1.5 J energy per pulse, respectively. Using the same laser power, the conventional method showed <0.5 mm total displacement. When reducing the phantom size to 5 × 5 × 5 mm 3 (one eighth in volume), the displacement was very inconsistent. The results suggested that using the pendulum model to eliminate the friction improved sensitivity and repeatability of the experiment. A detailed investigation on calculus movement and other causes of experimental variation will be conducted as a future study.

  12. Laser-polarized xenon-129 magnetic resonance spectroscopy and imaging. The development of a method for in vivo perfusion measurement

    Rosen, Matthew Scot

    2001-07-01

    This thesis presents in vivo nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) studies with laser-polarized 129Xe delivered to living rats by inhalation and transported to tissue via blood flow. The results presented herein include the observation, assignment, and dynamic measurement of 129Xe resonances in the brain and body, the first one- and two-dimensional chemical-shift-resolved images of 129Xe in blood, tissue, and gas in the thorax, and the first images of 129Xe in brain tissue. These results establish that laser-polarized 129Xe can be used as a magnetic resonance tracer in vivo. NMR resonances at 0, 191, 198, and 209 ppm relative to the 129 Xe gas resonance are observed in the rat thorax and assigned to 129Xe in gas, fat, tissue, and blood respectively. Resonances at 189, 192, 195, 198, and 209 ppm are observed in the brain, and the 195 and 209 ppm resonances are assigned to 129Xe in grey matter, and blood, respectively. The design and construction of a laser-polarized 129Xe production and delivery system is described. This system produces liter-volumes of laser- polarized 129Xe by spin-exchange optical- pumping. It represented an order of magnitude increase over previously reported production volumes of polarized 129Xe. At approximately 3-7% polarization, 157 cc-atm of xenon is produced and stored as ice every 5 minutes. This reliable, effective, and simple production method for large volumes of 129Xe can be applied to other areas of research involving the use of laser-polarized noble gases. A model of the in vivo transport of laser polarized 129Xe to tissue under realistic experimental NMR conditions is described. Appropriate control of the NMR parameters is shown to allow tissue perfasion and 129Xe tissue T1 to be extracted from measurement of the steady-state 129Xe tissue signal. In vivo rodent 129Xe NMR results are used to estimate the signal-to-noise ratio of this technique, and an inhaled 30% xenon/70% O2 mixture polarized to 5

  13. Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

    Kuznetsov, A. P., E-mail: APKuznetsov@mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Buzinskij, O. I. [State Research Center Troitsk Institute for Innovation and Fusion Research (TRINITI) (Russian Federation); Gubsky, K. L.; Nikitina, E. A.; Savchenkov, A. V.; Tarasov, B. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Tugarinov, S. N. [State Research Center Troitsk Institute for Innovation and Fusion Research (TRINITI) (Russian Federation)

    2015-12-15

    A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements.

  14. Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

    Kuznetsov, A. P.; Buzinskij, O. I.; Gubsky, K. L.; Nikitina, E. A.; Savchenkov, A. V.; Tarasov, B. A.; Tugarinov, S. N.

    2015-01-01

    A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements

  15. Comparison of Microleakage under Rebonded Stainless Steel Orthodontic Brackets Using Two Methods of Adhesive Removal: Sandblast and Laser.

    Tudehzaeim, Mohamad Hossein; Yassaei, Soghra; Taherimoghadam, Shohreh

    2015-02-01

    Debonding is a common occurrence in orthodontic treatment and a considerable number of orthodontists prefer to rebond the detached brackets because of economic issues. The aim of this study was to compare the microleakage beneath rebonded stainless steel brackets using two methods of adhesive removal namely sandblast and laser. Sixty human premolar teeth were randomly divided into three groups. Following bonding the brackets, group 1 served as the control group. Brackets in groups 2 and 3 were debonded, and adhesive removal from the bracket bases was done by means of sandblasting and Er-YAG laser, respectively. After rebonding, teeth in each group were stained with 2% methylene blue for 24 hours, sectioned and examined under a stereomicroscope. Marginal microleakage at the adhesive-enamel and bracket-adhesive interfaces in the occlusal and gingival margins was determined. Statistical analysis was done using the Kruskal-Wallis test. Comparison of the microleakage scores among the three groups revealed no statistically significant difference (P > 0.05). At the enamel-adhesive interface, the gingival margins in all groups showed higher microleakage while in the adhesive-bracket interface, the occlusal margin exhibited greater microleakage. Er-YAG laser irradiation and sandblasting for adhesive removal from the debonded brackets yielded clinically acceptable microleakage scores.

  16. Zeeman structure of red lines of lanthanum observed by laser spectroscopy methods

    Sobolewski, Ł. M.; Windholz, L.; Kwela, J.

    2017-11-01

    Laser Induced Fluorescence (LIF) Spectroscopy and Optogalvanic (OG) Spectroscopy were used for the investigation of the Zeeman hyperfine (hf) structures of 27 spectral lines of La I in the wavelength range between 633.86 and 667.54 nm. As a source of free La atoms a hollow cathode discharge lamp was used. Spectra were recorded in the presence of a relatively weak magnetic field (about 800G) produced by a permanent magnet, for two linear polarization directions of the exciting laser beam. As a result of the measurements, we determined for the first time the Landé gJ- factors of 18 levels of La I. The Landé gJ- factors of 12 other levels were re-investigated and determined with higher accuracy.

  17. Antimicrobial activity of biopolymer–antibiotic thin films fabricated by advanced pulsed laser methods

    Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Popescu, C.; Dorcioman, G.; Miroiu, F.M.; Socol, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Gittard, S.D.; Miller, P.R.; Narayan, R.J. [Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, NC 27599-7575 (United States); Enculescu, M. [National Institute for Materials Physics, PO Box MG-7, Bucharest-Magurele (Romania); Chrisey, D.B. [Tulane University, Department of Physics and Engineering Physics, New Orleans, LA (United States)

    2013-08-01

    We report on thin film deposition by matrix assisted pulsed laser evaporation (MAPLE) of two polymer–drug composite thin film systems. A pulsed KrF* excimer laser source (λ = 248 nm, τ = 25 ns, ν = 10 Hz) was used to deposit composite thin films of poly(D,L-lactide) (PDLLA) containing several gentamicin concentrations. FTIR spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical structures similar to those of drop cast materials. Scanning electron microscopy data indicated that MAPLE may be used to fabricate thin films of good morphological quality. The activity of PDLLA–gentamicin composite thin films against Staphylococcus aureus bacteria was demonstrated using drop testing. The influence of drug concentration on microbial viability was also assessed. Our studies indicate that polymer–drug composite thin films prepared by MAPLE may be used to impart antimicrobial activity to implants, medical devices, and other contact surfaces.

  18. Application of the 2-D discrete-ordinates method to multiple scattering of laser radiation

    Zardecki, A.; Gerstl, S.A.W.; Embury, J.F.

    1983-01-01

    The discrete-ordinates finite-element radiation transport code twotran is applied to describe the multiple scattering of a laser beam from a reflecting target. For a model scenario involving a 99% relative humidity rural aerosol we compute the average intensity of the scattered radiation and correction factors to the Beer-Lambert law arising from multiple scattering. As our results indicate, 2-D x-y and r-z geometry modeling can reliably describe a realistic 3-D scenario. Specific results are presented for the two visual ranges of 1.52 and 0.76 km which show that, for sufficiently high aerosol concentrations (e.g., equivalent to V = 0.76 km), the target signature in a distant detector becomes dominated by multiply scattered radiation from interactions of the laser light with the aerosol environment. The merits of the scaling group and the delta-M approximation for the transfer equation are also explored

  19. A new method to position the APS dipoles with the use of a laser tracker

    Friedsam, H.; Penicka, J.

    1994-01-01

    The alignment requirements for the synchrotron light sources have increased to the limit of today's alignment techniques. Some components such as dipoles can only be positioned after having obtained a three-dimensional outline of the as-built magnet. The laser tracking system provides the unique opportunity to map the dipole gap and relate the information to the outside reference marks for the placement of the magnet. In this case the Leica SMART 310 laser tracker is used as a 3D coordinate measuring system that provides the necessary information of twist, roll, sag, and gap changes over the full dipole length. On the basis of this information the best fitting plane is calculated to obtain the average roll angle for the positioning of the dipole. This paper describes the basic principal of this alignment technique and demonstrates the achieved results with examples

  20. Development and Validation of a Laser Induced Breakdown Spectrometry Method for Cancer Detection and Characterization

    Otieno, E.A.

    2015-01-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a type of atomic emission spectroscopy which employs a highly energetic laser pulse to simultaneously prepare the sample and excite the species. The simplest calibration technique is based on the use of standard calibration curves. The phenomenon of self-absorption may be considered as a factor of linearity deviation in conventional calibration. Chemometrics has the ability to extract underlying phenomena from complex data with the help of multivariate techniques such as SIMCA, ICA, PCA, SVM and ANNs. The techniques are also capable of capturing information about correlated trends in a given dataset. It has been reported that in normal liver the zinc concentration is about 78ug/g, wet weight and the primary liver cancer itself is about 18ug/g

  1. Laser assisted nuclear decay spectroscopy: A new method for studying neutron-deficient francium

    Lynch, Kara Marie

    2015-01-01

    Radioactive decay studies of rare isotopes produced at radioactive ion beam facilities have often been hindered by the presence of isobaric and isomeric contamination. The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, CERN uses laser radiation to stepwise excite and ionize an atomic beam in a particular isomeric state. Deflection of this selectively ionized beam of exotic nuclei, from the remaining neutral contaminants, allows ultra-sensitive detection of rare isotopes and nuclear structure measurements in background-free conditions.\

  2. Laser fusion

    Ashby, D.E.T.F.

    1976-01-01

    A short survey is given on laser fusion its basic concepts and problems and the present theoretical and experimental methods. The future research program of the USA in this field is outlined. (WBU) [de

  3. Laser spectroscopy

    Letokhov, V.S.

    1981-01-01

    This article describes recent progress in the application of laser atomic spectroscopy to study parameters of nuclei available in very small quantities; radioactive nuclei, rare isotopes, nuclear isomers, etc, for which study by conventional spectroscopic methods is difficult. (author)

  4. A novel baseline correction method using convex optimization framework in laser-induced breakdown spectroscopy quantitative analysis

    Yi, Cancan; Lv, Yong; Xiao, Han; Ke, Ke; Yu, Xun

    2017-12-01

    For laser-induced breakdown spectroscopy (LIBS) quantitative analysis technique, baseline correction is an essential part for the LIBS data preprocessing. As the widely existing cases, the phenomenon of baseline drift is generated by the fluctuation of laser energy, inhomogeneity of sample surfaces and the background noise, which has aroused the interest of many researchers. Most of the prevalent algorithms usually need to preset some key parameters, such as the suitable spline function and the fitting order, thus do not have adaptability. Based on the characteristics of LIBS, such as the sparsity of spectral peaks and the low-pass filtered feature of baseline, a novel baseline correction and spectral data denoising method is studied in this paper. The improved technology utilizes convex optimization scheme to form a non-parametric baseline correction model. Meanwhile, asymmetric punish function is conducted to enhance signal-noise ratio (SNR) of the LIBS signal and improve reconstruction precision. Furthermore, an efficient iterative algorithm is applied to the optimization process, so as to ensure the convergence of this algorithm. To validate the proposed method, the concentration analysis of Chromium (Cr),Manganese (Mn) and Nickel (Ni) contained in 23 certified high alloy steel samples is assessed by using quantitative models with Partial Least Squares (PLS) and Support Vector Machine (SVM). Because there is no prior knowledge of sample composition and mathematical hypothesis, compared with other methods, the method proposed in this paper has better accuracy in quantitative analysis, and fully reflects its adaptive ability.

  5. Methods of Laser Spectroscopy in Devices for Continuous Monitoring of O2 and CO Content in Boiler Smoke Gases

    V. A. Firago

    2006-01-01

    Full Text Available Application efficiency of various absorption laser spectroscopy methods for determination of gas component concentration in boiler smoke gases has been studied in the paper, O2 and CO absorption spectra have been analyzed, optimum absorption lines in near IR spectral range (about 0.76 µm for O2 and 1.56 µm for CO have been selected and graphical dependences of intensity and half-width of the selected lines on the investigated medium temperature and pressure have been shown. Processes of monitoring CO and O2 content in boiler smoke gases while using basic laser spectroscopy methods have been simulated and measuring errors have been analyzed. It has been found out that in order to decrease methodical errors of concentration measuring it is necessary to take into account the investigated medium temperature and pressure. The paper shows that the least errors of continuous CO and O2 concentration monitoring at the presence of variations in dissipative losses have been ensured by the modified correlation method though its threshold sensitivity is less than integral and correlation ones.

  6. A qualitative and quantitative laser-based computer-aided flow visualization method. M.S. Thesis, 1992 Final Report

    Canacci, Victor A.; Braun, M. Jack

    1994-01-01

    The experimental approach presented here offers a nonintrusive, qualitative and quantitative evaluation of full field flow patterns applicable in various geometries in a variety of fluids. This Full Flow Field Tracking (FFFT) Particle Image Velocimetry (PIV) technique, by means of particle tracers illuminated by a laser light sheet, offers an alternative to Laser Doppler Velocimetry (LDV), and intrusive systems such as Hot Wire/Film Anemometry. The method makes obtainable the flow patterns, and allows quantitative determination of the velocities, accelerations, and mass flows of an entire flow field. The method uses a computer based digitizing system attached through an imaging board to a low luminosity camera. A customized optical train allows the system to become a long distance microscope (LDM), allowing magnifications of areas of interest ranging up to 100 times. Presented in addition to the method itself, are studies in which the flow patterns and velocities were observed and evaluated in three distinct geometries, with three different working fluids. The first study involved pressure and flow analysis of a brush seal in oil. The next application involved studying the velocity and flow patterns in a cowl lip cooling passage of an air breathing aircraft engine using water as the working fluid. Finally, the method was extended to a study in air to examine the flows in a staggered pin arrangement located on one side of a branched duct.

  7. RESEARCH ON COORDINATE TRANSFORMATION METHOD OF GB-SAR IMAGE SUPPORTED BY 3D LASER SCANNING TECHNOLOGY

    P. Wang

    2018-04-01

    Full Text Available In the image plane of GB-SAR, identification of deformation distribution is usually carried out by artificial interpretation. This method requires analysts to have adequate experience of radar imaging and target recognition, otherwise it can easily cause false recognition of deformation target or region. Therefore, it is very meaningful to connect two-dimensional (2D plane coordinate system with the common three-dimensional (3D terrain coordinate system. To improve the global accuracy and reliability of the transformation from 2D coordinates of GB-SAR images to local 3D coordinates, and overcome the limitation of traditional similarity transformation parameter estimation method, 3D laser scanning data is used to assist the transformation of GB-SAR image coordinates. A straight line fitting method for calculating horizontal angle was proposed in this paper. After projection into a consistent imaging plane, we can calculate horizontal rotation angle by using the linear characteristics of the structure in radar image and the 3D coordinate system. Aided by external elevation information by 3D laser scanning technology, we completed the matching of point clouds and pixels on the projection plane according to the geometric projection principle of GB-SAR imaging realizing the transformation calculation of GB-SAR image coordinates to local 3D coordinates. Finally, the effectiveness of the method is verified by the GB-SAR deformation monitoring experiment on the high slope of Geheyan dam.

  8. Research on Coordinate Transformation Method of Gb-Sar Image Supported by 3d Laser Scanning Technology

    Wang, P.; Xing, C.

    2018-04-01

    In the image plane of GB-SAR, identification of deformation distribution is usually carried out by artificial interpretation. This method requires analysts to have adequate experience of radar imaging and target recognition, otherwise it can easily cause false recognition of deformation target or region. Therefore, it is very meaningful to connect two-dimensional (2D) plane coordinate system with the common three-dimensional (3D) terrain coordinate system. To improve the global accuracy and reliability of the transformation from 2D coordinates of GB-SAR images to local 3D coordinates, and overcome the limitation of traditional similarity transformation parameter estimation method, 3D laser scanning data is used to assist the transformation of GB-SAR image coordinates. A straight line fitting method for calculating horizontal angle was proposed in this paper. After projection into a consistent imaging plane, we can calculate horizontal rotation angle by using the linear characteristics of the structure in radar image and the 3D coordinate system. Aided by external elevation information by 3D laser scanning technology, we completed the matching of point clouds and pixels on the projection plane according to the geometric projection principle of GB-SAR imaging realizing the transformation calculation of GB-SAR image coordinates to local 3D coordinates. Finally, the effectiveness of the method is verified by the GB-SAR deformation monitoring experiment on the high slope of Geheyan dam.

  9. Semiconductor laser shearing interferometer

    Ming Hai; Li Ming; Chen Nong; Xie Jiaping

    1988-03-01

    The application of semiconductor laser on grating shearing interferometry is studied experimentally in the present paper. The method measuring the coherence of semiconductor laser beam by ion etching double frequency grating is proposed. The experimental result of lens aberration with semiconductor laser shearing interferometer is given. Talbot shearing interferometry of semiconductor laser is also described. (author). 2 refs, 9 figs

  10. In vivo study of the human skin by the method of laser-induced fluorescence spectroscopy

    Borisova, E.; Avramov, L.

    2000-01-01

    The goals of this study are to perform a preliminary evaluation of the diagnostic potential of noninvasive laser-induced auto-fluorescence spectroscopy (LIAFS) for human skin and optimize of detection and diagnosis of hollow organs and skin. In recent years, there has been growing interest in the use of laser-induced fluorescence to discriminate disease from normal surrounding tissue. The most fluorescence studies have used exogenous fluorophores of this discrimination. The laser-induced auto-fluorescence which is used for diagnosis of tissues in the human body avoids administration of any drugs. In this study a technique for optical biopsy of in vivo human skin is presented. The auto-fluorescence characterization of tissue relies on different spectral properties of tissues. It was demonstrated a differentiation between normal skin and skin with vitiligo. Two main endogenous fluorophores in the human skin account for most of the cellular auto-fluorescence for excitation wavelength 337 nm reduced from of nicotinamide adenine dinucleotide and collagen. The auto-fluorescence spectrum of human skin depend on main internal absorbers which are blood and melanin. In this study was described the effect caused by blood and melanin content on the shape of the auto-fluorescence spectrum of human skin. Human skin fluorescence spectrum might provide dermatologists with important information and such investigations are successfully used now in skin disease diagnostics, in investigation of the environmental factor impact or for evaluation of treatment efficiency. (authors)

  11. Method to measure the position offset of multiple light spots in a distributed aperture laser angle measurement system.

    Jing, Xiaoli; Cheng, Haobo; Xu, Chunyun; Feng, Yunpeng

    2017-02-20

    In this paper, an accurate measurement method of multiple spots' position offsets on a four-quadrant detector is proposed for a distributed aperture laser angle measurement system (DALAMS). The theoretical model is put forward, as well as the corresponding calculation method. This method includes two steps. First, as the initial estimation, integral approximation is applied to fit the distributed spots' offset function; second, the Boltzmann function is employed to compensate for the estimation error to improve detection accuracy. The simulation results attest to the correctness and effectiveness of the proposed method, and tolerance synthesis analysis of DALAMS is conducted to determine the maximum uncertainties of manufacturing and installation. The maximum angle error is less than 0.08° in the prototype distributed measurement system, which shows the stability and robustness for prospective applications.

  12. Beyond the Floquet theorem: generalized Floquet formalisms and quasienergy methods for atomic and molecular multiphoton processes in intense laser fields

    Chu, Shih-I.; Telnov, Dmitry A.

    2004-02-01

    The advancement of high-power and short-pulse laser technology in the past two decades has generated considerable interest in the study of multiphoton and very high-order nonlinear optical processes of atomic and molecular systems in intense and superintense laser fields, leading to the discovery of a host of novel strong-field phenomena which cannot be understood by the conventional perturbation theory. The Floquet theorem and the time-independent Floquet Hamiltonian method are powerful theoretical framework for the study of bound-bound multiphoton transitions driven by periodically time-dependent fields. However, there are a number of significant strong-field processes cannot be directly treated by the conventional Floquet methods. In this review article, we discuss several recent developments of generalized Floquet theorems, formalisms, and quasienergy methods, beyond the conventional Floquet theorem, for accurate nonperturbative treatment of a broad range of strong-field atomic and molecular processes and phenomena of current interests. Topics covered include (a) artificial intelligence (AI)-most-probable-path approach (MPPA) for effective treatment of ultralarge Floquet matrix problem; (b) non-Hermitian Floquet formalisms and complex quasienergy methods for nonperturbative treatment of bound-free and free-free processes such as multiphoton ionization (MPI) and above-threshold ionization (ATI) of atoms and molecules, multiphoton dissociation (MPD) and above-threshold dissociation (ATD) of molecules, chemical bond softening and hardening, charge-resonance enhanced ionization (CREI) of molecular ions, and multiple high-order harmonic generation (HHG), etc.; (c) many-mode Floquet theorem (MMFT) for exact treatment of multiphoton processes in multi-color laser fields with nonperiodic time-dependent Hamiltonian; (d) Floquet-Liouville supermatrix (FLSM) formalism for exact nonperturbative treatment of time-dependent Liouville equation (allowing for relaxations and

  13. Beyond the Floquet theorem: generalized Floquet formalisms and quasienergy methods for atomic and molecular multiphoton processes in intense laser fields

    Chu, S.-I.; Telnov, D.A.

    2004-01-01

    The advancement of high-power and short-pulse laser technology in the past two decades has generated considerable interest in the study of multiphoton and very high-order nonlinear optical processes of atomic and molecular systems in intense and superintense laser fields, leading to the discovery of a host of novel strong-field phenomena which cannot be understood by the conventional perturbation theory. The Floquet theorem and the time-independent Floquet Hamiltonian method are powerful theoretical framework for the study of bound-bound multiphoton transitions driven by periodically time-dependent fields. However, there are a number of significant strong-field processes cannot be directly treated by the conventional Floquet methods. In this review article, we discuss several recent developments of generalized Floquet theorems, formalisms, and quasienergy methods, beyond the conventional Floquet theorem, for accurate nonperturbative treatment of a broad range of strong-field atomic and molecular processes and phenomena of current interests. Topics covered include (a) artificial intelligence (AI)-most-probable-path approach (MPPA) for effective treatment of ultralarge Floquet matrix problem; (b) non-Hermitian Floquet formalisms and complex quasienergy methods for nonperturbative treatment of bound-free and free-free processes such as multiphoton ionization (MPI) and above-threshold ionization (ATI) of atoms and molecules, multiphoton dissociation (MPD) and above-threshold dissociation (ATD) of molecules, chemical bond softening and hardening, charge-resonance enhanced ionization (CREI) of molecular ions, and multiple high-order harmonic generation (HHG), etc.; (c) many-mode Floquet theorem (MMFT) for exact treatment of multiphoton processes in multi-color laser fields with nonperiodic time-dependent Hamiltonian; (d) Floquet-Liouville supermatrix (FLSM) formalism for exact nonperturbative treatment of time-dependent Liouville equation (allowing for relaxations and

  14. Development of a thermal fatigue test method for thermal barrier coatings by laser excitation using a laser thermal shock facility; Entwicklung eines Pruefverfahrens zur laserinduzierten thermischen Ermuedung thermischer Schutzschichten mittels einer Laser-Thermoschockpruefeinrichtung

    Nies, Daniel

    2012-07-13

    The finite nature of fossil fuel supply and the growing environmental awareness become increasingly stronger motivations for the development of efficient gas turbines and jet engines for power generation or as engines for land-, sea- and water-based vehicles. One concept developed for this purpose are thermal barrier coatings, where the thermal load of components is reduced by applying a ceramic coating onto the components. In this work the possibility to use a laser thermal shock facility for thermo-cyclic testing of thermal barrier coatings is examined. A focused laser beam is used for heating the sample and a homogeneous temperature distribution on the sample surface is achieved by the used trajectory and radial adjusted laser power. The required improvements of the existing testing facility are explained, including the development of a new sample holder and of the testing and evaluation routines for the experiments. For the assessment of the initiation and evolution of damages, acoustic emission and thermographic methods are used. The possibilities and limits of these methods are assessed during the experiments. The work also includes an extensive temperature dependent characterisation of the ceramic material used for the thermal barrier coating. In this part, the measurement of the Young's modulus by a dynamic method is to be highlighted, as this is a rarely used technique. The characterisations show the expected values, except for a lower porosity as expected by the manufacturer and no significant phase changes during isothermal heat treatments. To reach sample surface temperatures above 1000 C, it is necessary to increase the absorption by an additional coating of magnetite. The temperature distribution on the surface is measured by an infrared camera, which is calibrated for this purpose. With the incorporated active air cooling of the sample backside, the temperature gradient can be controlled, but still leaves room for improvements. Already without

  15. A new time-frequency method to reveal quantum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing transform

    Sheu, Yae-lin; Hsu, Liang-Yan; Wu, Hau-tieng; Li, Peng-Cheng; Chu, Shih-I

    2014-01-01

    This study introduces a new adaptive time-frequency (TF) analysis technique, the synchrosqueezing transform (SST), to explore the dynamics of a laser-driven hydrogen atom at an ab initio level, upon which we have demonstrated its versatility as a new viable venue for further exploring quantum dynamics. For a signal composed of oscillatory components which can be characterized by instantaneous frequency, the SST enables rendering the decomposed signal based on the phase information inherited in the linear TF representation with mathematical support. Compared with the classical type of TF methods, the SST clearly depicts several intrinsic quantum dynamical processes such as selection rules, AC Stark effects, and high harmonic generation

  16. Laser-ultrasound spectroscopy apparatus and method with detection of shear resonances for measuring anisotropy, thickness, and other properties

    Levesque, Daniel; Moreau, Andre; Dubois, Marc; Monchalin, Jean-Pierre; Bussiere, Jean; Lord, Martin; Padioleau, Christian

    2000-01-01

    Apparatus and method for detecting shear resonances includes structure and steps for applying a radiation pulse from a pulsed source of radiation to an object to generate elastic waves therein, optically detecting the elastic waves generated in the object, and analyzing the elastic waves optically detected in the object. These shear resonances, alone or in combination with other information, may be used in the present invention to improve thickness measurement accuracy and to determine geometrical, microstructural, and physical properties of the object. At least one shear resonance in the object is detected with the elastic waves optically detected in the object. Preferably, laser-ultrasound spectroscopy is utilized to detect the shear resonances.

  17. A statistical method for determining the dimensions, tolerances and specification of optics for the Laser Megajoule facility (LMJ)

    Denis, Vincent

    2008-09-01

    This paper presents a statistical method for determining the dimensions, tolerance and specifications of components for the Laser MegaJoule (LMJ). Numerous constraints inherent to a large facility require specific tolerances: the huge number of optical components; the interdependence of these components between the beams of same bundle; angular multiplexing for the amplifier section; distinct operating modes between the alignment and firing phases; the definition and use of alignment software in the place of classic optimization. This method provides greater flexibility to determine the positioning and manufacturing specifications of the optical components. Given the enormous power of the Laser MegaJoule (over 18 kJ in the infrared and 9 kJ in the ultraviolet), one of the major risks is damage the optical mounts and pollution of the installation by mechanical ablation. This method enables estimation of the beam occultation probabilities and quantification of the risks for the facility. All the simulations were run using the ZEMAX-EE optical design software.

  18. Development of a Method for the Determination of Chromium and Cadmium in Tannery Wastewater Using Laser-Induced Breakdown Spectroscopy

    Mahwish Bukhari

    2012-01-01

    Full Text Available This paper illustrates systematic development of a convenient analytical method for the determination of chromium and cadmium in tannery wastewater using laser-induced breakdown spectroscopy (LIBS. A new approach was developed by which liquid was converted into solid phase sample surface using absorption paper for subsequent LIBS analysis. The optimized values of LIBS parameters were 146.7 mJ for chromium and 89.5 mJ for cadmium (laser pulse energy, 4.5 μs (delay time, 70 mm (lens to sample surface distance, and 7 mm (light collection system to sample surface distance. Optimized values of LIBS parameters demonstrated strong spectrum lines for each metal keeping the background noise at minimum level. The new method of preparing metal standards on absorption papers exhibited calibration curves with good linearity with correlation coefficients, R2 in the range of 0.992 to 0.998. The developed method was tested on real tannery wastewater samples for determination of chromium and cadmium.

  19. Correlation between macro texture measures carried out by the volumetric method and by different laser texture meter

    Parra Ruiz, L.; Yanguas Gonzalez, S. J.

    2013-01-01

    The reference value for the measurement of surface macro texture in the Spanish Main Road Network is the MTD or Mean Texture Depth (PMT, Profundidad Media de Textura), obtained by means of the volumetric methods, in accordance with the standard UNE EN 13036-1:12010. The fact that it is a spot measurement that requires road closures makes it an expensive procedure as well as slow and dangerous. In addition to this, the test results are relatively sensitive to the operator, being the procedure not too suitable for systematic surveys. These are some of the reasons that have contributed to the development of texture meter laser devices that can be assembled on board of vehicles, circulating without interfering with the normal traffic flow and providing a parameter named the MPD (Mean Depth Profile). According to the standard UNE-EN ISO 13473-1:2006, it is possible to estimate the texture obtained by volumetric methods, with the parameter ETD (Estimated Texture Depth) through the equation: ETD=0,8 x MPD+0.2 In 2008 CEDEX conducted a study that correlated macro texture measures obtained by means of the volumetric method with such carried out by different laser texture meters. The equations yield a better relation between MPD and MTD were dependent on the measurement device used and were not linear equations type, as is it indicated in the standard, but exponential type equations. (Author) 6 refs.

  20. Structural and optical properties of {beta}-FeSi{sub 2}/Si(100) prepared by laser ablation method

    Kakemoto, H; Makita, Y; Obara, A; Tsai, Y; Sakuragi, S; Ando, S; Tsukamoto, T

    1997-07-01

    {beta}-FeSi{sub 2} is a promising material for the application of various electronic, optoelectronic and energy devices. The authors present here the semiconducting properties of {beta}-FeSi{sub 2} films on Si(100) substrate prepared by laser ablation method. Samples were grown using poly-crystalline bulk {beta}-FeSi{sub 2} prepared by horizontal gradient freeze method. For the monitoring of growth, in-situ observation of ablation plume was made through fluorescence spectroscopy. Reflection of high-energy electron beam diffraction (RHEED) was also made in-situ to see the surface morphology. Characterization of the films by X-ray diffraction presented purely {beta}(220) orientation. Raman scattering measurements at room temperature also indicated that the grown films are semiconducting {beta}-FeSi{sub 2}. Optical absorption spectra at room temperature showed absorption coefficient higher than 10{sup 5} cm{sup {minus}1} above the band-gap ({approximately}1.2 eV). It was revealed that high quality semiconducting {beta}-FeSi{sub 2} films can be fabricated by laser ablation method without post-annealing.

  1. An Improved Measurement Method for the Strength of Radiation of Reflective Beam in an Industrial Optical Sensor Based on Laser Displacement Meter

    Youngchul Bae

    2016-05-01

    Full Text Available An optical sensor such as a laser range finder (LRF or laser displacement meter (LDM uses reflected and returned laser beam from a target. The optical sensor has been mainly used to measure the distance between a launch position and the target. However, optical sensor based LRF and LDM have numerous and various errors such as statistical errors, drift errors, cyclic errors, alignment errors and slope errors. Among these errors, an alignment error that contains measurement error for the strength of radiation of returned laser beam from the target is the most serious error in industrial optical sensors. It is caused by the dependence of the measurement offset upon the strength of radiation of returned beam incident upon the focusing lens from the target. In this paper, in order to solve these problems, we propose a novel method for the measurement of the output of direct current (DC voltage that is proportional to the strength of radiation of returned laser beam in the received avalanche photo diode (APD circuit. We implemented a measuring circuit that is able to provide an exact measurement of reflected laser beam. By using the proposed method, we can measure the intensity or strength of radiation of laser beam in real time and with a high degree of precision.

  2. An Improved Measurement Method for the Strength of Radiation of Reflective Beam in an Industrial Optical Sensor Based on Laser Displacement Meter.

    Bae, Youngchul

    2016-05-23

    An optical sensor such as a laser range finder (LRF) or laser displacement meter (LDM) uses reflected and returned laser beam from a target. The optical sensor has been mainly used to measure the distance between a launch position and the target. However, optical sensor based LRF and LDM have numerous and various errors such as statistical errors, drift errors, cyclic errors, alignment errors and slope errors. Among these errors, an alignment error that contains measurement error for the strength of radiation of returned laser beam from the target is the most serious error in industrial optical sensors. It is caused by the dependence of the measurement offset upon the strength of radiation of returned beam incident upon the focusing lens from the target. In this paper, in order to solve these problems, we propose a novel method for the measurement of the output of direct current (DC) voltage that is proportional to the strength of radiation of returned laser beam in the received avalanche photo diode (APD) circuit. We implemented a measuring circuit that is able to provide an exact measurement of reflected laser beam. By using the proposed method, we can measure the intensity or strength of radiation of laser beam in real time and with a high degree of precision.

  3. Treatment of cosmetic tattoos with nonablative fractional laser in an animal model: a novel method with histopathologic evidence.

    Wang, Chia-Chen; Huang, Chuen-Lin; Lee, Shao-Chen; Sue, Yuh-Mou; Leu, Fur-Jiang

    2013-02-01

    Cosmetic tattoos are difficult to treat using Q-switched lasers. We introduce a novel method for the treatment of cosmetic tattoos using a nonablative fractional laser and investigate the underlying pathophysiological mechanisms in an animal model. Ten rats were tattooed on their backs with white and flesh-colored pigments. One-half of each tattoo was treated with a 1,550-nm, erbium:glass fractional laser system with energy settings of 17 mJ and 169 MTZ/cm(2)  × 2 passes for five sessions at 1-month intervals. The untreated half of each tattoo served as the control. An independent physician reviewed the photographs and scored the clinical response. Serial skin samples were obtained at baseline and at various times after laser treatment. These tissue sections were stained with hematoxylin and eosin, and immunostained for types I, III, and IV collagen; laminin; fibronectin; and α-smooth muscle actin. White tattoos showed excellent responses in two rats and good responses in eight rats, whereas flesh-colored tattoos showed excellent responses in four rats and good responses in six rats (P = 0.001 in both cases compared with baseline). Both tattoos exhibited a similar clearance rate (P > 0.05) and histological reactions. Microscopic epidermal necrotic debris (MEND) containing tattoo pigments and collagen fibrils appeared on day 1, increased on day 2, and was exfoliated after 5 days. The dermal-epidermal junction lost integrity 30 minutes after treatment, but recovered completely on day 3. The expression of fibronectin and collagen-III, which play key roles in wound healing, increased around the microscopic treatment zone on days 1-5 and 4-7, respectively. A few myofibroblasts appeared on days 4-7. Nonablative fractional lasers (NAFLs) successfully remove cosmetic tattoos by transepidermal elimination of tattoo pigments through the disrupted dermal-epidermal junction. This action is facilitated by the wound healing process. Copyright © 2013 Wiley

  4. Determination of Trace Available Heavy Metals in Soil Using Laser-Induced Breakdown Spectroscopy Assisted with Phase Transformation Method.

    Yi, Rongxing; Yang, Xinyan; Zhou, Ran; Li, Jiaming; Yu, Huiwu; Hao, Zhongqi; Guo, Lianbo; Li, Xiangyou; Lu, Yongfeng; Zeng, Xiaoyan

    2018-05-18

    To detect available heavy metals in soil using laser-induced breakdown spectroscopy (LIBS) and improve its poor detection sensitivity, a simple and low cost sample pretreatment method named solid-liquid-solid transformation was proposed. By this method, available heavy metals were extracted from soil through ultrasonic vibration and centrifuging and then deposited on a glass slide. Utilization of this solid-liquid-solid transformation method, available Cd and Pb elements in soil were detected successfully. The results show that the regression coefficients of calibration curves for soil analyses reach to more than 0.98. The limits of detection could reach to 0.067 and 0.94 ppm for available Cd and Pb elements in soil under optimized conditions, respectively, which are much better than those obtained by conventional LIBS.

  5. Observation of dusts by laser scattering method in the JIPPT-IIU tokamak

    Narihara, K.; Toi, K.; Hamada, Y.

    1997-03-01

    Laser scattering signals which indicate the presence of small dusts (diameter ≤ 2 μm) were occasionally observed in the JIPPT-IIU tokamak chamber. This phenomenon was reproduced by deliberately spreading carbon dusts from the top of the vacuum chamber. No noticeable effect on the plasma was observed for dust-fall of up to at least 10 6 dusts (10 μg) in 20 ms during discharge. Dusts fallen just before the plasma start-up seemed to be confined but soon be ejected in less than 30 ms. (author)

  6. A new method for detection of the electron temperature in laser-plasma short wave cut off of stimulated Raman scattering spectrum

    Zhang Jiatai

    1994-01-01

    From the theory of stimulated Raman scattering (SRS) three wave interaction, a new method of detecting the electron temperature in laser-plasma is obtained. SRS spectrum obtained from Shenguang No. 12 Nd-laser experiments are analysed. Using the wave length of short wave cut off of SRS, the electron temperature in corona plasma region is calculated consistently. These results agree reasonable with X-ray spectrum experiments

  7. Fabrication Of Scaffolds From Ti6Al4V Powders Using The Computer Aided Laser Method

    Dobrzański L.A.

    2015-06-01

    Full Text Available The aim of the research, the results of which are presented in the paper, is to fabricate, by Selective Laser Melting (SLM, a metallic scaffold with Ti6Al4V powder based on a virtual model corresponding to the actual loss of a patient’s craniofacial bone. A plaster cast was made for a patient with a palate recess, and the cast was then scanned with a 3D scanner to create a virtual 3D model of a palate recess, according to which a 3D model of a solid implant was created using specialist software. The virtual 3D solid implant model was converted into a 3D porous implant model after designing an individual shape of the unit cell conditioning the size and three-dimensional shape of the scaffold pores by multiplication of unit cells. The data concerning a virtual 3D porous implant model was transferred into a selective laser melting (SLM device and a metallic scaffold was produced from Ti6Al4V powder with this machine, which was subjected to surface treatment by chemical etching. An object with certain initially adopted assumptions, i.e. shape and geometric dimensions, was finally achieved, which perfectly matches the patient bone recesses. The scaffold created was subjected to micro-and spectroscopic examinations.

  8. Nd:YAG laser annealing investigation of screen-printed CIGS layer on PET: Layer annealing method for photovoltaic cell fabrication process

    Alsaggaf, Ahmed

    2014-06-01

    Cu(In, Ga)Se2 (CIGS) ink was formulated from CIGS powder, polyvinyl butyral PVB, terpineol and polyester/polyamine co-polymeric dispersant KD-1. Thin films with different thicknesses were deposited on PET substrate using screen-printing followed by heat treatment using a Nd:YAG laser. The structure and morphology of the heated thin films were studied. The characterization of the CIGS powder, ink, and film was done using TGA, SEM, FIB, EDS, and XRD. TGA analysis shows that the CIGS ink is drying at 200 °C, which is well below the decomposition temperature of the PET substrate. It was observed by SEM that 20 pulses of 532nm and 60 mJ/cm2 Nd:YAG laser annealing causes atomic diffusion on the near surface area. Furthermore, FIB cross section images were utilized to monitor the effect of laser annealing in the depth of the layer. Laser annealing effects were compared to as deposited layer using XRD in reference to CIGS powder. The measurement shows that crystallinity of deposited CIGS is retained while EDS quantification and atomic ratio result in gradual loss of selenium as laser energy increases. The laser parameters were tuned in an effort to utilize laser annealing of screen-printed CIGS layer as a layer annealing method for solar cell fabrication process.

  9. Efficiency of the confocal method of laser endomicroscopy in complex diagnoses of diseases of common bile duct

    Anaskin, S G; Korniletsky, I D; Panchenkov, D N; Chertyuk, V B; Sazonov, D V; Zabozlayev, F G; Danilevskaya, O V; Mokshina, N V

    2017-01-01

    One of the more frequent manifestations of diseases of the bile ducts are its’ strictures or stenoses that could be of either malignant or benign nature. Current methods of diagnosing this pathology include computer tomography (CT) scan, magnetic resonance cholangiopancreatography (MRCP), endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP). However, these methods are not always informative, which makes this a current and topical problem. A fundamentally new method that broadens the capabilities of ERCP when diagnosing diseases of the bile duct accompanied by the development of strictures or stenoses is probe-based confocal laser endomicroscopy (pCLE). The method is based on the principle of confocal fluorescence microscopy. The most elaborate complications arise with the presence of the pre-existing pancreatobiliary pathology: pseudotumoral chronic pancreatitis, acute cholangitis, etc. Early stage cholangiocarcinoma diagnosis can be difficult (and not always possible) even with the help of modern research methods. For the timely diagnostic it is advantageous to conduct pCLE and targeted biopsy of the zone with most manifested changes. In all instances, the first use of the pCLE method for diagnostic purposes allowed us to clarify and correctly verify the diagnosis. When concerning the diseases of the bile duct, the modern stage of pCLE development can be of critical importance when other methods are not effective. (paper)

  10. Ablation of CdTe with 100 μs Nd:YAG laser pulses: dependence on target preparation method

    Rzeszutek, J.; Savchuk, V.; Oszwaldowski, M.

    2008-01-01

    The results of experimental studies of the ablation of CdTe with a pulsed Nd:YAG laser (wavelength 1064 nm) performed with 100 μs pulses and repetition time of 35 Hz are presented for the pulse energy range from 0.13 to 0.25 J. The main goal is to elucidate the dependence of the ablation process on the target preparation method. The investigation of the vapour stream intensity and chemical composition and their evolution with time are performed with a quadrupole mass spectrometer synchronized with the laser pulses. These studies are performed for three kinds of targets: a target made of CdTe bulk crystal (BC target), a target made of CdTe fine powder pressed under the pressure of 700 atm (PP target), and a target made of loose CdTe powder (N-PP target). The applicability of these targets for obtaining high quality CdTe thin films is determined. The best chemical composition of the vapour stream can be obtained with the BC target. A major drawback of this target is the energetic threshold for ablation with Nd:YAG laser and resulting delay in the ablation process above the threshold. The advantage of powder targets over BC target is the lack of any ablation threshold or delay. Weaker angular dependence of the particle emission (associated with the surface roughness), if confirmed in further experiments, can be the most important advantage of PP and N-PP targets. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Particle size distribution in soils and marine sediments by laser diffraction using Malvern Mastersizer 2000—method uncertainty including the effect of hydrogen peroxide pretreatment

    Callesen, Ingeborg; Keck, Hannes; Andersen, Thorbjørn Joest

    2018-01-01

    with less than 1% C and some marine sediments. Materials and methods: The method uncertainty for particle size analysis by the laser diffraction method using or not using H2O2 pretreatment followed by 2 min ultrasound and 1-mm sieving was determined for two soil samples and two aquatic sediments......Purpose: Methods for particle size distribution (PSD) determination by laser diffraction are not standardized and differ between disciplines and sectors. The effect of H2O2 pretreatment before a sonication treatment in laser diffraction analysis of soils and marine sediments was examined on soils...... pretreatment on the PSD was small and not significant. The standard deviation (std) in particle size fractions increased with particle size. PSDs and std for some samples were presented for future reference. Similar to other studies, the content of clay and silt (by sieving/hydrometer, SHM) was lower...

  12. Application of High-performance Visual Analysis Methods to Laser Wakefield Particle Acceleration Data

    Rubel, Oliver; Prabhat, Mr.; Wu, Kesheng; Childs, Hank; Meredith, Jeremy; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Ahern, Sean; Weber, Gunther H.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes

    2008-01-01

    Our work combines and extends techniques from high-performance scientific data management and visualization to enable scientific researchers to gain insight from extremely large, complex, time-varying laser wakefield particle accelerator simulation data. We extend histogram-based parallel coordinates for use in visual information display as well as an interface for guiding and performing data mining operations, which are based upon multi-dimensional and temporal thresholding and data subsetting operations. To achieve very high performance on parallel computing platforms, we leverage FastBit, a state-of-the-art index/query technology, to accelerate data mining and multi-dimensional histogram computation. We show how these techniques are used in practice by scientific researchers to identify, visualize and analyze a particle beam in a large, time-varying dataset

  13. Analysis of the imaging method for the assessment of the smile of laser diode bars

    Marti-Lopez, Luis; Ramos-de-Campos, Jose A.; Furlan, Walter D.

    2009-01-01

    Imaging systems designed for the assessment of the smile of laser diode bars (LDBs) are studied. The magnification matrix is derived from the required sampling period and the geometries of the LDB and the charge coupled device (CCD) array. These imaging systems present in-plane pure translation invariance, but lack in-plane rotation invariance. It is shown that the smile parameters of the image of the LDB are linked with the smile parameters of the LDB by simple mathematical expressions. The spatial resolution of such optical systems is estimated at about 1μm for a mean wavelength λ ∼ 800 nm and a fast axis divergence φ ∼ 20 o - 30 o . Our results suggest that imaging systems for LDB smile assessment can be used for assessing smile heights in the 1μm 10μm range. (Author)

  14. The Isolation of Pure Populations of Neurons by Laser Capture Microdissection: Methods and Application in Neuroscience.

    Morris, Renée; Mehta, Prachi

    2018-01-01

    In mammals, the central nervous system (CNS) is constituted of various cellular elements, posing a challenge to isolating specific cell types to investigate their expression profile. As a result, tissue homogenization is not amenable to analyses of motor neurons profiling as these represent less than 10% of the total spinal cord cell population. One way to tackle the problem of tissue heterogeneity and obtain meaningful genomic, proteomic, and transcriptomic profiling is to use laser capture microdissection technology (LCM). In this chapter, we describe protocols for the capture of isolated populations of motor neurons from spinal cord tissue sections and for downstream transcriptomic analysis of motor neurons with RT-PCR. We have also included a protocol for the immunological confirmation that the captured neurons are indeed motor neurons. Although focused on spinal cord motor neurons, these protocols can be easily optimized for the isolation of any CNS neurons.

  15. The development of skin immersion clearing method for increasing of laser exposure efficiency on subcutaneous objects

    Kozina, Alexandra M.; Genina, Elina A.; Terentyuk, Georgy S.; Terentyuk, Artem G.; Bashkatov, Alexey N.; Tuchin, Valery V.; Khlebtsov, Boris N.

    2012-06-01

    In this paper we have studied effect of a hyperosmotic optical clearing agent (OCA), such as polyethylene glycol, on the fluorescence intensity from a target located in subcutaneous area in the model experiments. As a fluorescence agent the nanocomposite including gold nanorods with hematophorphyrin was used. The remitted fluorescent signal traveling to the tissue surface was monitored over time as the tissue was treated with the OCA. The detected fluorescent signal increased as the scattering in tissue samples was substantially reduced. The study has shown how OCA can be used to improve the detected signal at localization of subcutaneous target tissue at the photothermal or photodynamic therapy. Immersion clearing of skin can be also useful for improvement of laser exposure efficiency due to the increasing of light penetration depth.

  16. Method for pulse control in a laser including a stimulated brillouin scattering mirror system

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2007-10-23

    A laser system, such as a master oscillator/power amplifier system, comprises a gain medium and a stimulated Brillouin scattering SBS mirror system. The SBS mirror system includes an in situ filtered SBS medium that comprises a compound having a small negative non-linear index of refraction, such as a perfluoro compound. An SBS relay telescope having a telescope focal point includes a baffle at the telescope focal point which blocks off angle beams. A beam splitter is placed between the SBS mirror system and the SBS relay telescope, directing a fraction of the beam to an alternate beam path for an alignment fiducial. The SBS mirror system has a collimated SBS cell and a focused SBS cell. An adjustable attenuator is placed between the collimated SBS cell and the focused SBS cell, by which pulse width of the reflected beam can be adjusted.

  17. An iterative method for unfolding time-resolved soft x-ray spectra of laser plasmas

    Tang Yongjian; Shen Kexi; Xu Hepin

    1991-01-01

    Dante-recorded temporal waveforms have been unfolded by using Fast Fourier transformation (FFT) and the inverted convolution theorem of Fourier analysis. The conversion of the signals to time-dependent soft x-ray spectra is accomplished on the IBM-PC/XT-286 microcomputer system with the code DTSP including SAND II reported by W.N.Mcelory et al.. An amplitude-limited iterative and periodic smoothing technique has been developed in the code DTSP. Time-resolved soft x-ray spectra with sixteen time-cell, and time-dependent radiation, [T R (t)], have been obtained for hohlraum targets irradiated with laser beams (λ = 1.06 μm) on LF-12 in 1989

  18. Intrauterine device for laser light diffusion and method of using the same

    Tadir, Y.; Berns, M.W.; Svaasand, L.O.; Tromberg, B.J.

    1995-12-26

    An improved device for delivery of photoenergy from a light source, such as a laser, into a uterine cavity for photodynamic therapy is comprised of a plurality of optic fibers, which are bundled together and inserted into the uterine cavity by means of a uterine cannula. The cannula is positioned within the uterine cavity at a preferred location and then withdrawn thereby allowing the plurality of optic fibers to splay or diverge one from the other within the cavity. Different portions of the distal tip of the optic fiber is provided with a light diffusing tip, the remainder being provided with a nondiffusing tip portion. The fiber optic shape, as well as the segment which is permitted to actively diffuse light through the tip, is selected in order to provide a more uniform exposure intensity of the photo energy or at least sufficient radiation directed to each segment of the uterine walls. 5 figs.

  19. Laser guiding at>1018 W/cm2 in plasma channels formed by the ignitor heater method

    Geddes, C.G.R.; Toth, C.; vanTilborg, J.; Leemans, W.P.

    2004-01-01

    Experiments explore guiding of intense laser pulses, optimization using channel formation beams and gas jet targets, and the interplay of channel guiding and relativistic self guiding. Impact on laser wakefield particle acceleration is being assessed

  20. Lasers '89

    Harris, D.G.; Shay, T.M.

    1990-01-01

    This book covers the following topics: XUV, X-Ray and Gamma-Ray Lasers, excimer lasers, chemical lasers, nuclear pumped lasers, high power gas lasers, solid state lasers, laser spectroscopy. The paper presented include: Development of KrF lasers for fusion and Nuclear driven solid-state lasers