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Sample records for excimer laser induced

  1. Excimer laser applications

    International Nuclear Information System (INIS)

    Fantoni, R.

    1988-01-01

    This lecture deals with laser induced material photoprocessing, especially concerning those processes which are initiated by u.v. lasers (mostly excimer laser). Advantages of using the u.v. radiation emitted by excimer lasers, both in photophysical and photochemical processes of different materials, are discussed in detail. Applications concerning microelectronics are stressed with respect to other applications in different fields (organic chemistry, medicine). As further applications of excimer lasers, main spectroscopic techniques for ''on line'' diagnostics which employ excimer pumped dye lasers, emitting tunable radiation in the visible and near u.v. are reviewed

  2. Excimer Laser Technology

    CERN Document Server

    Basting, Dirk

    2005-01-01

    This comprehensive survey on Excimer Lasers investigates the current range of the technology, applications and devices of this commonly used laser source, as well as the future of new technologies, such as F2 laser technology. Additional chapters on optics, devices and laser systems complete this compact handbook. A must read for laser technology students, process application researchers, engineers or anyone interested in excimer laser technology. An effective and understandable introduction to the current and future status of excimer laser technology.

  3. excimer laser

    Indian Academy of Sciences (India)

    2014-01-07

    Jan 7, 2014 ... is necessary to deposit one order higher input electric power into gas medium than ... cross-sectional view of the laser system is shown in figure 2A. The system mainly consists ... Considering the simplicity and reliability of the.

  4. Electrodeless excimer laser

    International Nuclear Information System (INIS)

    Lisi, N.

    2001-01-01

    In this paper it is proposed how to build an excimer laser based on an electrodeless discharge (or Dielectric Barrier Discharge). Such laser could operate with a low energy per pulse ( 2 excimer molecule, whose emission wavelength in the VUV range (157 nm) at high reprate is particularly interesting in the micro-lithography field [it

  5. Tunable excimer lasers

    International Nuclear Information System (INIS)

    Sze, R.C.

    1990-01-01

    The wide bandwidth nature of the rare-gas halide excimer transitions allow reasonable tuning of the laser oscillation wavelength that makes it useful for a number of applications. At the same time this wide bandwidth makes narrow band operation difficult and special techniques are needed to insure narrow frequency lasing as well as absolute frequency resettability. The author discusses briefly some of the classical frequency narrowing techniques and then goes on to some recent work that require lasers of special frequency characteristics for special applications including KrF laser fusion

  6. High power excimer laser

    International Nuclear Information System (INIS)

    Oesterlin, P.; Muckenheim, W.; Basting, D.

    1988-01-01

    Excimer lasers emitting more than 200 W output power are not commercially available. A significant increase requires new technological efforts with respect to both the gas circulation and the discharge system. The authors report how a research project has yielded a laser which emits 0.5 kW at 308 nm when being UV preionized and operated at a repetition rate of 300 Hz. The laser, which is capable of operating at 500 Hz, can be equipped with an x-ray preionization module. After completing this project 1 kW output power will be available

  7. Excimer laser decontamination

    Science.gov (United States)

    Sentis, Marc L.; Delaporte, Philippe C.; Marine, Wladimir; Uteza, Olivier P.

    2000-04-01

    The application of excimer laser ablation process to the decontamination of radioactive surfaces is discussed. This technology is very attractive because it allows to efficiently remove the contaminated particles without secondary waste production. To demonstrate the capability of such technology to efficiently decontaminate large area, we studied and developed a prototype which include a XeCl laser, an optical fiber delivery system and an ablated particles collection cell. The main physical processes taking place during UV laser ablation will be explained. The influence of laser wavelength, pulse duration and absorption coefficient of material will be discussed. Special studies have been performed to understand the processes which limit the transmission of high average power excimer laser through optical fiber, and to determine the laser conditions to optimize the value of this transmission. An in-situ spectroscopic analysis of laser ablation plasma allows the real time control of the decontamination. The results obtained for painting or metallic oxides removal from stainless steel surfaces will be presented.

  8. Excimer-laser-induced activation of Mg-doped GaN layers

    International Nuclear Information System (INIS)

    Lin, Y.-J.; Liu, W.-F.; Lee, C.-T.

    2004-01-01

    In this study, we investigated the 248 nm excimer-laser-induced activation of the Mg-doped GaN layers. According to the observed photoluminescence results and the x-ray photoelectron spectroscopy measurements, we found that the dissociation of the Mg-H complexes and the formation of hydrogenated Ga vacancies (i.e., V Ga H 2 ) and/or the Ga vacancies occupied by interstitial Mg during the laser irradiation process, led to an increase in the hole concentration

  9. Composition of the excimer laser-induced plume produced during LASIK refractive surgery

    Science.gov (United States)

    Glickman, Randolph D.; Liu, Yun; Mayo, George L.; Baribeau, Alan D.; Starck, Tomy; Bankhead, Tom

    2003-07-01

    Because of concerns about potential hazards to surgical personnel of the plume associated with laser refractive surgery, this study was performed to characterize the composition of such plumes. Filter elements were removed from the smoke evacuator of a VISX S3 excimer laser (filter pore size ~0.3 microns) and from a Mastel Clean Room ( filter pore size ~0.2 microns) used with a LADARVISION excimer laser. The filters from both laser systems captured the laser-induced plumes from multiple, routine, LASIK patient procedures. Some filters were processed for scanning electron microscopy, while others were extracted with methanol and chloroform for biochemical analysis. Both the VISX "Final Air" filter and the Mastel "Clean Room" filter captured material that was not observed in filters that had clean operating room air only passed through them. In the VISX system, air flows through the filter unit parallel to the filter matrix. SEM analysis showed these filters captured discrete particles of 0.3 to 3.0 microns in size. In the Mastel Clean Room unit, air flows orthogonally through the filter, and the filter matrix was heavily layered with captured debris so that individual particles were not readily distinguished. Amino acid analysis and gel electrophoresis of extracted material revealed proteinaceous molecules as large as 5000 molecular weight. Such large molecules in the laser plume are not predicted by the existing theory of photochemical ablation. The presence of relatively large biomolecules may constitute a risk of allergenic reactions in personnel exposed to the plume, and also calls into question the precise mechanism of excimer laser photochemical ablation. Supported by the RMG Research Endowment, and Research to Prevent Blindness

  10. Excimer laser technology

    International Nuclear Information System (INIS)

    Mace, P.N.

    1980-01-01

    Scaling presently available excimer laser systems to lasers designed to operate at high average power and high pulse repetition rates for long periods of time requires advances in many areas of engineering technology. For economical application to industrial processes, the efficiency must be increased. This leads to more stringent requirements on preionization techniques, energy delivery systems, and system chemistry. Long life operation (> 10 9 to 10 10 pulses) requires development of new pulse power components, optical elements and flow system components. A broad-based program underway at the Los Alamos Scientific Laboratory is addressing these key technology issues, with the help of advanced component and systems development programs in industry. A prototype XeCl laser meeting all requirements for efficiency, system performance and life is scheduled for completion in 1984

  11. Excimer-laser-induced permanent electrical conductivity in solid C60 films

    International Nuclear Information System (INIS)

    Ning, D.; Lou, Q.H.; Dong, J.X.; Wei, Y.R.

    1996-01-01

    After being irradiated in air by a XeCl (308 nm) excimer laser, the electrical conductivity of solid thin-film C 60 has been improved by more than six orders of magnitudes. The products resulting from laser irradiation of C 60 films have been investigated by Raman scattering and the onset of conductivity can be attributed to laser-induced oxygenation and disintegration of the fullerene. Irradiated by ∼40 ns laser pulses with different fluence, products with different microstructure were observed. At lower fluence, the Raman features of microcrystalline graphite and fullerene polymer were observed. At a fluence just below the ablation threshold (36 mJ/cm 2 ), the fullerene molecules in the film were disintegrated completely and transformed to amorphous graphite. (orig.). With 5 figs

  12. The argon excimer laser

    International Nuclear Information System (INIS)

    Wrobel, W.G.

    1981-02-01

    The electron-beam-pumped argon eximer laser is investigated and tuned for the first time. The electron beam is generated by means of an improved coaxial field emmision diode in which argon gas is excited with power densities of 0.3 GW/cm 3 for 18 ns. The processes in the excited gas of 20 to 65 bar are described in the context of a kinetic model as a sequence of stationary states. Investigations of the amplified spontaneous emission (superfluorescence) confirm the predictions of this model. Only the absorption due to the excited Ar atoms is anomalously high. Reproducible operation of the argon eximer laser was achieved in a wide pressure range with various resonator arrangements. The wavelength of this shortest wavelength of this shortest wavelength excimer laser is 126 nm, the laser line width approx. 1.7 nm, the pulse length 7 to 13 ns, and the laser power 250 kW. The laser emission is tuned from 123.2 nm to 128.4 nm by two different methods (diffraction grating and prism). This tunable laser is thus the one with the shortest wavelength at present. Its line width is 0.25 to 0.4 nm, and the power ue 1.7 kW. (orig.)

  13. Excimer laser corneal surgery and free oxygen radicals.

    Science.gov (United States)

    Bilgihan, K; Bilgihan, A; Akata, F; Hasanreisoğlu, B; Türközkan, N

    1996-01-01

    Corneal photoablation with 193 nm argon fluoride excimer laser is a new technique for the treatment of refractive errors and for removing corneal opacities and irregularities. Ultraviolet radiation and thermal injury induce free radical formation in the tissues. The aim of this study was to confirm the production of free radicals by excimer laser photoablation in rabbits. The thermal changes of the posterior corneal surface were recorded during excimer laser photoablation. The lipid peroxide (LPO) levels and superoxide dismutase (SOD) activities of aqueous humour were measured after excimer laser keratectomy. The aqueous LPO levels were not changed after excimer laser ablation, but both the thermal increase in the cornea during the photoablation and the decreased aqueous SOD activities suggest that free radicals are formed in the cornea during excimer laser keratectomy, and that they may be responsible for some of the complications of excimer laser corneal surgery.

  14. Comparing laser induced plasmas formed in diode and excimer pumped alkali lasers.

    Science.gov (United States)

    Markosyan, Aram H

    2018-01-08

    Lasing on the D 1 transition (6 2 P 1/2 → 6 2 S 1/2 ) of cesium can be reached in both diode and excimer pumped alkali lasers. The first uses D 2 transition (6 2 S 1/2 → 6 2 P 3/2 ) for pumping, whereas the second is pumped by photoexcitation of ground state Cs-Ar collisional pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (excimers). Despite lasing on the same D 1 transition, differences in pumping schemes enables chemical pathways and characteristic timescales unique for each system. We investigate unavoidable plasma formation during operation of both systems side by side in Ar/C 2 H 6 /Cs.

  15. Excimer laser phototherapeutic keratectomy.

    Science.gov (United States)

    Ayres, Brandon D; Rapuano, Christopher J

    2006-10-01

    Anterior corneal pathology, such as corneal scars and corneal stromal dystrophies, can be visually devastating. Over the past decade, there was a shift in treatment of these conditions from corneal transplantation to phototherapeutic keratectomy (PTK) using the 193 nm excimer laser for visual restoration. We have reviewed the recent literature on techniques for performing and refining PTK and also on various pathologic conditions that can be treated with PTK. The primary indications for PTK include anterior corneal dystrophies, such as lattice, granular, and Reis-Bückler's dystrophy. PTK can produce significant visual improvement in these patients, and corneal transplantation or retransplantation can be delayed. Corneal degenerations, such as Salzmann's nodular degeneration, keratoconus nodules, and climatic droplet keratopathy, also can be successfully treated with PTK. Additionally, anterior corneal scars from such etiologies as trauma, corneal ulcers, and prior refractive surgery can have visual improvement with PTK. In summary, PTK is a powerful tool for the management of anterior corneal pathology. In a properly selected and well-counseled patient, PTK can significantly improve vision and quality of life.

  16. Modeling of excimer laser radiation induced defect generation in fluoride phosphate glasses

    International Nuclear Information System (INIS)

    Natura, U.; Ehrt, D.

    2001-01-01

    Fluoride phosphate (FP) glasses with low phosphate content are high-transparent in the deep ultraviolet (UV) range and attractive candidates for UV-optics. Their optical properties are complementary to fluoride crystals. The anomalous partial dispersion makes them desirable for optical lens designs to reduce the secondary spectrum. Their UV transmission is limited by trace impurities introduced by raw materials and decreases when exposed to UV-radiation (lamps, lasers). The experiments of the paper published previously in this journal were used in order to separate radiation induced absorption bands in the fluoride phosphate glass FP10. In this paper the generation mechanism of the phosphorus-oxygen related hole center POHC 2 is investigated in detail in glasses of various compositions (various phosphate and impurity contents) in order to predict the transmission loss in case of long-time irradiation. Experiments were carried out using ArF- and KrF-excimer lasers (ns-pulses). POHC 2 generation strongly depends on the phosphate content and on the content of Pb 2+ . A model was developed on these terms. Rate equations are formulated, incorporating the influence of the Pb 2+ -content on the defect generation, a two-step creation term including an energy transfer process and a one-photon bleaching term. This results in a set of coupled nonlinear differential equations. Absorption coefficients and lifetimes of the excited states were calculated as well. Experimental results compared well with the numerical analysis of the theoretical rate equations

  17. Excimer-laser-irradiation-induced effects in C60 films for photovoltaic applications

    International Nuclear Information System (INIS)

    Narayanan, K.L.; Yamaguchi, M.; Azuma, H.

    2002-01-01

    Thin films of fullerene C 60 deposited by the molecular-beam epitaxy method have been subjected to a 248 nm excimer laser for various timings. Reduction in the electrical resistance of the films and the spectral evolution of the D and G bands in the Raman spectra, due to the sharp tendency towards graphitization accompanied by an increasing level of structural disorder, are observed during laser irradiation. Based on the above results, an attempt has been carried out on these irradiated C 60 films to make a device sandwiched with n-type Si, and the photovoltaic parameters are reported as a function of the laser exposure times

  18. Microstructures induced by excimer laser surface melting of the SiC{sub p}/Al metal matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Qian, D.S., E-mail: Daishu.qian@postgrad.manchester.ac.uk; Zhong, X.L.; Yan, Y.Z.; Hashimoto, T.; Liu, Z.

    2017-08-01

    Highlights: • Microstructural analysis of the excimer laser-melted SiC{sub p}/AA2124;. • Analytical, FEM, and SPH simulation of the laser-material interaction;. • Mechanism of the formation of the laser-induced microstructure. - Abstract: Laser surface melting (LSM) was carried out on the SiC{sub p}/Al metal matrix composite (MMC) using a KrF excimer laser with a fluence of 7 J/cm{sup 2}. The re-solidification microstructure was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy dispersive X-ray detector, and X-ray diffraction (XRD) analysis. It was found that a 2.5 μm thick melted layer was formed in the near-surface region, in which dissolution of the intermetallics and removal of the SiC particles occurred. The thermal and material response upon laser irradiation was simulated using three models, i.e. analytical model, finite element model (FEM) and smoothed-particle hydrodynamics (SPH) model. The effect of SiC particles on the LSM process, the mechanism of the SiC removal and the re-solidification microstructures in the melted layer were discussed. The simulation results were in good agreement with the experimental results and contributed to the generic understanding of the re-solidification microstructures induced by ns-pulsed lasers.

  19. Excimer laser decomposition of silicone

    International Nuclear Information System (INIS)

    Laude, L.D.; Cochrane, C.; Dicara, Cl.; Dupas-Bruzek, C.; Kolev, K.

    2003-01-01

    Excimer laser irradiation of silicone foils is shown in this work to induce decomposition, ablation and activation of such materials. Thin (100 μm) laminated silicone foils are irradiated at 248 nm as a function of impacting laser fluence and number of pulsed irradiations at 1 s intervals. Above a threshold fluence of 0.7 J/cm 2 , material starts decomposing. At higher fluences, this decomposition develops and gives rise to (i) swelling of the irradiated surface and then (ii) emission of matter (ablation) at a rate that is not proportioned to the number of pulses. Taking into consideration the polymer structure and the foil lamination process, these results help defining the phenomenology of silicone ablation. The polymer decomposition results in two parts: one which is organic and volatile, and another part which is inorganic and remains, forming an ever thickening screen to light penetration as the number of light pulses increases. A mathematical model is developed that accounts successfully for this physical screening effect

  20. Semiconductor processing with excimer lasers

    International Nuclear Information System (INIS)

    Young, R.T.; Narayan, J.; Christie, W.H.; van der Leeden, G.A.; Rothe, D.E.; Cheng, L.J.

    1983-01-01

    The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisons of the quality of annealing of ion-implanted Si obtained with XeCl and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si at uv and visible wavelengths, the efficiency of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCl laser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCl laser annealed region are 2 to 3 orders of magnitude lower than that obtained from ruby or Nd:YAG lasers. All these results seem to suggest that XeCl lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications

  1. Structural and morphological transformations of TiO2 nanotube arrays induced by excimer laser treatment

    International Nuclear Information System (INIS)

    Hsu, Ming-Yi; Thang, Nguyen Van; Wang Chih; Leu Jihperng

    2012-01-01

    The structural and morphological transformations of TiO 2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400 °C for 1 h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25 ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85° was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs. - Highlights: ► We examined the morphology and microstructure of TNAs treated by ELA. ► Crystallinity of parallel ELA-treated TNAs reached ∼50% of furnace anneal. ► Tilted ELA at 85o enhanced the degree of crystallization in TNAs to 90%.

  2. Decontamination by excimer laser

    International Nuclear Information System (INIS)

    2001-01-01

    The process developed in collaboration with the C.N.R.S. has reached the industrial stage. The transport by optical fibre beam has been perfected and allows to work from a distance of 20 m from the source. Demonstration has been made with a laser of a 500 watt power which allows a 5 to 10 m 2 /hour etching efficiency. This process is in the course of qualification in collaboration with the different organisations: C.E.A., COGEMA and E.D.F. This qualification concerns 25 different materials and zircaloy fuel claddings. (author)

  3. Putative photoacoustic damage in skin induced by pulsed ArF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, S.; Flotte, T.J.; McAuliffe, D.J.; Jacques, S.L.

    1988-05-01

    Argon-fluoride excimer laser ablation of guinea pig stratum corneum causes deeper tissue damage than expected for thermal or photochemical mechanisms, suggesting that photoacoustic waves have a role in tissue damage. Laser irradiation (193 nm, 14-ns pulse) at two different radiant exposures, 62 and 156 mJ/cm2 per pulse, was used to ablate the 15-microns-thick stratum corneum of the skin. Light and electron microscopy of immediate biopsies demonstrated damage to fibroblasts as deep as 88 and 220 microns, respectively, below the ablation site. These depths are far in excess of the optical penetration depth of 193-nm light (1/e depth = 1.5 micron). The damage is unlikely to be due to a photochemical mechanism because (a) the photons will not penetrate to these depths, (b) it is a long distance for toxic photoproducts to diffuse, and (c) damage is proportional to laser pulse intensity and not the total dose that accumulates in the residual tissue; therefore, reciprocity does not hold. Damage due to a thermal mechanism is not expected because there is not sufficient energy deposited in the tissue to cause significant heating at such depths. The damage is most likely due to a photoacoustic mechanism because (a) photoacoustic waves can propagate deep into tissue, (b) the depth of damage increases with increasing laser pulse intensity rather than with increasing total residual energy, and (c) the effects are immediate. These effects should be considered in the evaluation of short pulse, high peak power laser-tissue interactions.

  4. Excimer laser: a module of the alopecia areata common protocol.

    Science.gov (United States)

    McMichael, Amy J

    2013-12-01

    Alopecia areata (AA) is an autoimmune condition characterized by T cell-mediated attack of the hair follicle. The inciting antigenic stimulus is unknown. A dense perbulbar lymphocytic infiltrate and reproducible immunologic abnormalities are hallmark features of the condition. The cellular infiltrate primarily consists of activated T lymphocytes and antigen-presenting Langerhans cells. The xenon chloride excimer laser emits its total energy at the wavelength of 308 nm and therefore is regarded as a "super-narrowband" UVB light source. Excimer laser treatment is highly effective in psoriasis, another T cell-mediated disorder that shares many immunologic features with AA. The excimer laser is superior in inducing T cell apoptosis in vitro compared with narrowband UVB, with paralleled improved clinical efficacy. The excimer laser has been used successfully in patients with AA. In this context, evaluation of the potential benefit of 308-nm excimer laser therapy in the treatment of AA is clinically warranted. Herein, the use of a common treatment protocol with a specifically designed module to study the outcome of excimer laser treatment on moderate-to-severe scalp AA in adults is described.

  5. Laser spectroscopy of the products of photoevaporation with a short-wavelength (λ = 193 nm) excimer laser

    International Nuclear Information System (INIS)

    Gochelashvili, K S; Zemskov, M E; Evdokimova, O N; Mikhkel'soo, V T; Prokhorov, A M

    1999-01-01

    An excimer laser spectrometer was designed and constructed. It consists of a high-vacuum interaction chamber, a short-wavelength (λ = 193 nm) excimer ArF laser used for evaporation, a probe dye laser pumped by an XeCl excimer laser, and a system for recording a laser-induced fluorescence signal. This spectrometer was used to investigate nonthermal mechanisms of photoevaporation of a number of wide-gap dielectrics. (laser applications and other topics in quantum electronics)

  6. 308nm Excimer Laser in Dermatology

    Science.gov (United States)

    Mehraban, Shadi

    2014-01-01

    308nm xenon-chloride excimer laser, a novel mode of phototherapy, is an ultraviolet B radiation system consisting of a noble gas and halide. The aim of this systematic review was to investigate the literature and summarize all the experiments, clinical trials and case reports on 308-nm excimer laser in dermatological disorders. 308-nm excimer laser has currently a verified efficacy in treating skin conditions such as vitiligo, psoriasis, atopic dermatitis, alopecia areata, allergic rhinitis, folliculitis, granuloma annulare, lichen planus, mycosis fungoides, palmoplantar pustulosis, pityriasis alba, CD30+ lympho proliferative disorder, leukoderma, prurigo nodularis, localized scleroderma and genital lichen sclerosus. Although the 308-nm excimer laser appears to act as a promising treatment modality in dermatology, further large-scale studies should be undertaken in order to fully affirm its safety profile considering the potential risk, however minimal, of malignancy, it may impose. PMID:25606333

  7. 308-nm excimer laser in endodontics

    Science.gov (United States)

    Liesenhoff, Tim

    1992-06-01

    Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

  8. Excimer laser beam profile recording based on electrochemical etched polycarbonate

    International Nuclear Information System (INIS)

    Parvin, P.; Jaleh, B.; Zangeneh, H.R.; Zamanipour, Z.; Davoud-Abadi, Gh.R.

    2008-01-01

    There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler

  9. Excimer laser beam profile recording based on electrochemical etched polycarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Parvin, P. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of)], E-mail: parvin@aut.ac.ir; Jaleh, B. [Physics Department, Bu-Ali Sina University, Postal Code 65174, Hamedan (Iran, Islamic Republic of); Zangeneh, H.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Zamanipour, Z. [Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of); Davoud-Abadi, Gh.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of)

    2008-08-15

    There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler.

  10. Excimer Laser Curing Of Polymer Coatings

    Science.gov (United States)

    Klick, David; Akerman, M. Alfred; Paul, George L.; Supurovic, Darko; Tsuda, Haruki

    1988-12-01

    The use of the excimer laser as a source of energy for photo-assisted curing of industrial polymeric coatings was investigated. Presently, UV lamps are sometimes used to excite a photoinitiating molecule mixed with the starting monomers and oligomers of a coating. The resulting polymeric chain reaction multiplies the effect of the initial photons, making economical use of the light source. The high cost of laser photons may thus be justifiable if lasers provide advantages over lamps. A series of visibly transparent 7 μm coatings (a typical thickness for 'slick' magazine coatings) with various photoinitiators, monomers, and oligomers was illuminated with excimer laser light of various wavelengths, fluences, and pulse repetition rates. For the optimum parameters, it was found that the laser had large advantages in curing speed over existing UV lamp processes, due to its monochromaticity. Pigmented coatings (20 μm TiO2 mixtures typical of appliance or automotive finishes) are not easily cured with UV lamps due to the inability of light to penetrate the absorbing and scattering pigmented layer. However, economically-viable cure rates were achieved with certain photoinitiators using a tunable excimer-pumped dye laser. A prototype of such a laser suitable for factory use was built and used to cure these coatings. Results are scaled to a factory situation, and costs are calculated to show the advantages of the laser method over currently used processes.

  11. Treatment of oral lichen planus using 308-nm excimer laser.

    Science.gov (United States)

    Liu, Wei-Bing; Sun, Li-Wei; Yang, Hua; Wang, Yan-Fei

    2017-09-01

    Oral lichen planus (OLP) is a chronic inflammatory disease, has prolonged courses, repeated attacks and resistance to treatment. The traditional narrow spectrum UVB treatment has an established efficacy on skin lichen planus, and high safety. However, most of ultraviolet phototherapy devices have a huge volume, thereby cannot be used in the treatment of OLP. Lymphocytic infiltration is evident in the lesions of lichen planus, and the direct irradiation of 308-nm excimer laser can induce apoptosis of the T lymphocytes in skin lesions, thereby has a unique therapeutic effect on the diseases involving T lymphocytes. This study aims to investigate the efficacy of 308-nm excimer laser in the treatment of OLP. A total of six OLP patients were enrolled into this study, and further pathological diagnosis was conducted, then 308-nm excimer laser was used in the treatment. The efficacy of 308-nm excimer laser in the treatment of OLP was satisfactory. The clinical symptoms of five patients were significantly improved. In two patients, the erosion surface based on congestion and the surrounding white spots completely disappeared, and clinical recovery was achieved. Three patients achieved partial remission, that is, the erosion surface healed, congestion and white spot area shrunk by more than 1/2 of the primary skin lesions. In the remaining one patient, the erosion surface had not completely healed after treatment, and congestion and white spot area shrunk by less than 1/2 of the primary skin lesions. Only one patients had developed mild pain during the treatment, and this symptom alleviated by itself. The 308-nm excimer laser therapy can serve as a safe and effective treatment for OLP. © 2017 Wiley Periodicals, Inc.

  12. Prototype of an excimer laser for microprocessing

    Science.gov (United States)

    Iwanejko, Leszek; Pokora, Ludwik J.; Wolinski, Wieslaw L.

    1991-08-01

    The paper presents a brief description of a prototype of a XeC1 excimer laser for micraprocessing of materials. The planned main parameters of the laserare as follows: wavelength . . . . . . . . . . . . . . . . . . . . . . . . . 308 nm -''energyofapulse. . . . . . . . . . . . . lOOmJ -pulseduration (FWHM) . . . . . . . . . . . . . . . 2Ons repetition frequency . . . . . . . . . . . . . . 1O Hz peak power of a pulse . . . . . . . . . . . . . . . 5 MW With respect to currently carrried works with the prototype we show only preliminary results of testing of a laser head. The obtained maximum laser pulse energy exceeded 90 ml. However it should be pointed out that this value was obtained without any opt i mi z at i on of the 1 aser.

  13. Excimer laser irradiation of metal surfaces

    Science.gov (United States)

    Kinsman, Grant

    In this work a new method of enhancing CO2 laser processing by modifying the radiative properties of a metal surface is studied. In this procedure, an excimer laser (XeCl) or KrF) exposes the metal surface to overlapping pulses of high intensity, 10(exp 8) - 10(exp 9) W cm(exp -2), and short pulse duration, 30 nsec FWHM (Full Width Half Maximum), to promote structural and chemical change. The major processing effect at these intensities is the production of a surface plasma which can lead to the formation of a laser supported detonation wave (LSD wave). This shock wave can interact with the thin molten layer on the metal surface influencing to a varying degree surface oxidation and roughness features. The possibility of the expulsion, oxidation and redeposition of molten droplets, leading to the formation of micron thick oxide layers, is related to bulk metal properties and the incident laser intensity. A correlation is found between the expulsion of molten droplets and a Reynolds number, showing the interaction is turbulent. The permanent effects of these interactions on metal surfaces are observed through scanning electron microscopy (SEM), transient calorimetric measurements and Fourier transform infrared (FTIR) spectroscopy. Observed surface textures are related to the scanning procedures used to irradiate the metal surface. Fundamental radiative properties of a metal surface, the total hemispherical emissivity, the near-normal spectral absorptivity, and others are examined in this study as they are affected by excimer laser radiation. It is determined that for heavily exposed Al surface, alpha' (10.6 microns) can be increased to values close to unity. Data relating to material removal rates and chemical surface modification for excimer laser radiation is also discussed. The resultant reduction in the near-normal reflectivity solves the fundamental problem of coupling laser radiation into highly reflective and conductive metals such as copper and aluminum. The

  14. Calculation of high-pressure argon plasma parameters produced by excimer laser

    International Nuclear Information System (INIS)

    Tsuda, Norio; Yamada, Jun

    2000-01-01

    When a XeCl excimer laser light was focused in a high-pressure argon gas up to 150 atm, a dense plasma developed not only backward but also forward. It is important to study on the electron density and temperature of the laser-induced plasma in the high-pressure gas. The electron density and temperature in high-pressure argon plasma produced by XeCl excimer laser has been calculated and compared with the experimental data. (author)

  15. Surface processing by high power excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Stehle, M [SOPRA, 92 - Bois-Colombes (France)

    1995-03-01

    Surface processing with lasers is a promising field of research and applications because lasers bring substantial advantages : laser beams work at distance, laser treatments are clean in respect of environment consideration and they offer innovative capabilities for surface treatment which cannot be reached by other way. Excimer lasers are pulsed, gaseous lasers which emit in UV spectral range - the most common are XeCl (308 nm), KrF (248 nm), ArF (193 nm). From 1980 up to 1994, many of them have been used for research, medical and industrial applications such as spectroscopy, PRK (photo-refractive keratotomy) and micro-machining. In the last six years, from 1987 up to 1993, efforts have been done in order to jump from 100 W average power up to 1 kW for XeCl laser at {lambda} = 308 nm. It was the aim of AMMTRA project in Japan as EU205 and EU213 Eureka projects in Europe. In this framework, SOPRA developed VEL (Very large Excimer Laser). In 1992, 1 kW (10 J x 100 Hz) millstone has been reached for the first time, this technology is based on X-Ray preionization and large laser medium (5 liters). Surface treatments based on this laser source are the main purpose of VEL Lasers. Some of them are given for instance : (a) Turbine blades made with metallic substrate and ceramic coatings on the top, are glazed in order to increase corrosion resistance of ceramic and metal sandwich. (b) Selective ablation of organic coatings deposited on fragile composite material is investigated in Aerospace industry. (c) Chock hardening of bulk metallic materials or alloys are investigated for automotive industry in order to increase wear resistance. (d) Ablation of thin surface oxides of polluted steels are under investigation in nuclear industry for decontamination. (J.P.N.).

  16. Surface processing by high power excimer laser

    International Nuclear Information System (INIS)

    Stehle, M.

    1995-01-01

    Surface processing with lasers is a promising field of research and applications because lasers bring substantial advantages : laser beams work at distance, laser treatments are clean in respect of environment consideration and they offer innovative capabilities for surface treatment which cannot be reached by other way. Excimer lasers are pulsed, gaseous lasers which emit in UV spectral range - the most common are XeCl (308 nm), KrF (248 nm), ArF (193 nm). From 1980 up to 1994, many of them have been used for research, medical and industrial applications such as spectroscopy, PRK (photo-refractive keratotomy) and micro-machining. In the last six years, from 1987 up to 1993, efforts have been done in order to jump from 100 W average power up to 1 kW for XeCl laser at λ = 308 nm. It was the aim of AMMTRA project in Japan as EU205 and EU213 Eureka projects in Europe. In this framework, SOPRA developed VEL (Very large Excimer Laser). In 1992, 1 kW (10 J x 100 Hz) millstone has been reached for the first time, this technology is based on X-Ray preionization and large laser medium (5 liters). Surface treatments based on this laser source are the main purpose of VEL Lasers. Some of them are given for instance : a) Turbine blades made with metallic substrate and ceramic coatings on the top, are glazed in order to increase corrosion resistance of ceramic and metal sandwich. b) Selective ablation of organic coatings deposited on fragile composite material is investigated in Aerospace industry. c) Chock hardening of bulk metallic materials or alloys are investigated for automotive industry in order to increase wear resistance. d) Ablation of thin surface oxides of polluted steels are under investigation in nuclear industry for decontamination. (J.P.N.)

  17. Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas y Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F.; Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati (Roma) (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-02-26

    A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

  18. Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

    International Nuclear Information System (INIS)

    Conde, J.C.; Martin, E.; Gontad, F.; Chiussi, S.; Fornarini, L.; Leon, B.

    2010-01-01

    A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

  19. Excimer laser development for fusion

    International Nuclear Information System (INIS)

    Giovanielli, D.

    1985-01-01

    The future utility of inertial confinement fusion requires a new driver. Successful experiments coupling laser energy to targets, and our understanding of fuel capsule behavior strongly suggest that a laboratory thermonuclear source is attainable and power production may be considered if a suitable driver with high efficiency, high repetition rate, and most importantly, low capital cost, can be identified. No adequate driver exists today; however, the krypton fluoride laser holds great promise. By the end of this decade, driver development can be brought to the point that a technically justifiable choice can be made for the future direction of ICF

  20. Photochemical and Spectroscopic Effects Resulting from Excimer Laser Excitation.

    Science.gov (United States)

    Wang, Xuan Xiao

    I. Photochemical production of ozone from pure oxygen using excimer lasers. Production of ozone was observed from experiments when oxygen was under a broadband pulsed KrF laser radiation. The production process was found to be autocatalytic. Mechanisms for the ozone formation were proposed. Experimental results over a range of oxygen pressure and laser pulse energy (irradiance) provided evidences in favor of the proposed mechanisms. Experiments were also numerically modeled. Good agreement between the experimental and the numerical results were observed, which provided further evidence to support the proposed mechanisms. Cross sections for some photochemical processes in the mechanisms were estimated. Production of ozone from pure oxygen under a ArF excimer laser radiation (193 nm) was also studied and numerically modeled. Effects of ambient water vapor on ozone production were investigated. Experimental results showed a fast ozone destruction when water vapor was present in the cell. However, numerical results obtained from the well-known OH and HO _2 chain ozone destruction mechanism predicted a slower ozone destruction. Possible reasons for the discrepancy are discussed. II. Resonance-enhanced multiphoton ionization of N_2 at 193 and 248 nm detected by N_sp{2}{+} fluorescence. Using a broadband excimer laser operating at 193 and 248 nm multiphoton ionization at high pressures in air and pure nitrogen has been detected by fluorescence from N_sp{2}{+} in the B-X firstnegative system. Measurements of the fluorescence intensity as a function of beam irradiance indicate resonance in N_2 at the energy of two 193 nm photons (2 + 1 REMPI) and three 248 nm photons (3 + 1 REMPI). Possible intermediate states are discussed. III. Excimer laser-induced fluorescence from some organic solvents. Fluorescence was observed from vapor phase benzene, toluene, p-xylene, benzyl chloride, methyl benzoate, acetic anhydride, ether, methanol, ethyl acetone, acetone, and 2-butanone using

  1. Electrodeless excimer laser; Laser a eccimeri senza elettrodi

    Energy Technology Data Exchange (ETDEWEB)

    Lisi, N. [ENEA, Divisione Nuovi Materiali, Centro Ricerche Casaccia, Rome (Italy)

    2001-07-01

    In this paper it is proposed how to build an excimer laser based on an electrodeless discharge (or Dielectric Barrier Discharge). Such laser could operate with a low energy per pulse (<100 mJ) and a high repetition rate (<100 kHz). The most relevant advantage an electrodeless DBD laser is the much longer gas mixture lifetime. This feature could allow the operation of a sealed laser emitting higher average power with respect to commercially available excimer lasers. Such discharge scheme could be advantageous in order to excite the F{sub 2} excimer molecule, whose emission wavelength in the VUV range (157 nm) at high reprate is particularly interesting in the micro-lithography field. [Italian] In questo documento viene proposto come costruire un laser a eccimeri basato su una scarica priva di elettrodi, o Dielectric Barrier Discharge. Tale laser puo' funzionare con una bassa energia per impulso (<100 mJ) ad alta frequenza di ripetizione (<100 kHz). Il vantaggio fondamentale di un laser a DBD e quindi privo di elettrodi e' la vita media della miscela gassosa molto piu' alta che potrebbe permettere alla camera laser di operare sigillata ad una potenza media superiore a quella dei laser a eccimeri attuali. Tale schema di pompaggio potrebbe essere particolarmente vantaggioso per eccitare la molecola eccimero F{sub 2} la cui lunghezza di emissione nel VUV (157 nm) ad elevata frequenza di ripetizione presenta un notevole interesse nel campo della produzione di microcircuiti.

  2. Excimer Pumped Pulsed Tunable Dye Laser

    Science.gov (United States)

    Littman, Michael G.

    1988-06-01

    It has been recently shown and reported for the first time at this meeting, that Excimer pumping of a single-mode, short-cavity, grazing-incidence, longitudinally-pumped pulsed dye laser is feasible. In this paper the key concepts upon which this latest development is based are presented and are in a somewhat unusual form. This manuscript describes five specific dye laser examples. The five examples represent a progression from the simplest type of dye laser to the single-mode version mentioned above. The examples thus serve as a tutorial introduction to potential users of dye lasers. The article is organized into five sections or STEPS, each of which describes a different pulsed dye laser. Since the subtle points about dye lasers are best appreciated only after one actually attempts to build a working model, a PROCEDURES category is included in which details about the construction of the particular form of laser are given. As one reads through this category, think of it as looking over the shoulder of the laser builder. The NOTES category which follows is a brief but essential discussion explaining why various components and procedures are used, as well as how laser performance specifications are obtained. This subsection can he viewed as a discussion with the laser builder concerning the reasons for specific actions and choices made in the assembly of the example laser. The last category contains COMMENTS which provide additional related information pertaining to the example laser that goes beyond the earlier annotated discussion. If you like, these are the narrator's comments. At the end of the article, after the five sequential forms of the laser have been presented, there is a brief summation.

  3. Krypton excimer laser oscillation by discharge pumping

    International Nuclear Information System (INIS)

    Shirai, Takahiro; Tabe, Yoshitaka; Kubodera, Shoichi; Sasaki, Wataru; Kawanaka, Junji

    2001-01-01

    We have demonstrated vacuum ultraviolet (VUV) laser oscillation of the krypton excimer (Kr 2 *) excited by a compact self-sustained discharge device. We have observed a spectral narrowing of the Kr 2 * emission centered at 147.8 nm. A deconvoluted spectral width is 0.5 nm (FWHM), which reveals a contrast to a 13 nm spectral width of the spontaneous emission. The Kr 2 * intensity has increased one order of magnitude when a charging voltage was increased larger than 29 kV. The success of the lasing in the VUV spectral region has been attributed to the success of a stable glow discharge of Kr at 10 atm. The pulse width of the VUV laser radiation is 400 ns (FWHM). The maximum output energy measured is as large as 150 μJ. (author)

  4. ArF Excimer Laser-induced Deposition of Ag/C Nanocomposite Thin Films in the Presence of n-Hexane

    Czech Academy of Sciences Publication Activity Database

    Gondal, M.A.; Fajgar, Radek; Chang, X.; Shen, K.; Xu, Q.

    2014-01-01

    Roč. 311, AUG 30 (2014), s. 95-100 ISSN 0169-4332 Grant - others:NNSFCH(CN) 51172044; NSFJP(CN) BK2011617; KFUPM(CN) RG 1311-1 Institutional support: RVO:67985858 Keywords : ArF excimer laser * nanocomposite * laser deposition Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.711, year: 2014

  5. [Glycosaminoglycans in subepithelial opacity after excimer laser keratectomy].

    Science.gov (United States)

    Nakayasu, K; Gotoh, T; Ishikawa, T; Kanai, A

    1996-05-01

    We evaluated histochemically the characteristics of glycosaminoglycans and proteoglycans in the corneal subepithelial opacity after excimer laser keratectomy on rabbit corneas. We also performed the same evaluations on the cornea after mechanical keratectomy. Twenty days after the operations, the area immediately subjacent to the epithelium showed strong staining with toluidine blue, alcian blue, and colloidal iron. However, after treatment with chondroitinase ABC or chondroitinase AC, alcian blue staining in this area decreased dramatically. Antilarge proteoglycan antibody also reacted strongly in this area. Histochemical and immunohistochemical examination of the cornea where mechanical keratectomy was done showed basically similar findings with the cornea of excimer laser keratectomy. These results suggest that large-molecula proteoglycans with chondroitine sulfate side chains become localized in the subepithelial area after two different kinds of keratectomies. We presume from histochemical and immunohistochemical observations that the subepithelial opacity observed after excimer laser keratectomy is not a special reaction to excimer laser but simply a corneal scar formed after stromal resection.

  6. Recent advances in excimer laser technology at Los Alamos

    International Nuclear Information System (INIS)

    Bigio, I.J.; Czuchlewski, S.; McCown, A.W.; Taylor, A.J.

    1991-01-01

    This paper reports that current research in excimer laser technology at Los Alamos progresses in two major areas: In the Bright Source program, the development of ultra-high brightness (sub-piosecond) laser systems, based on discharge -pumped excimer laser amplifiers, continues Recently the authors have completed rigorous measurements of the saturation parameter for ultra-short pulses. In the laser fusion program, implementation of the large KrF laser fusion amplifiers have been accompanied by numerous studies of the laser physics and kinetics of large e-beam pumped devices

  7. Excimer laser surface modification: Process and properties

    Energy Technology Data Exchange (ETDEWEB)

    Jervis, T.R.; Nastasi, M. [Los Alamos National Lab., NM (United States); Hirvonen, J.P. [Technical Research Institute, Espoo (Finland). Metallurgy Lab.

    1992-12-01

    Surface modification can improve materials for structural, tribological, and corrosion applications. Excimer laser light has been shown to provide a rapid means of modifying surfaces through heat treating, surface zone refining, and mixing. Laser pulses at modest power levels can easily melt the surfaces of many materials. Mixing within the molten layer or with the gas ambient may occur, if thermodynamically allowed, followed by rapid solidification. The high temperatures allow the system to overcome kinetic barriers found in some ion mixing experiments. Alternatively, surface zone refinement may result from repeated melting-solidification cycles. Ultraviolet laser light couples energy efficiently to the surface of metallic and ceramic materials. The nature of the modification that follows depends on the properties of the surface and substrate materials. Alloying from both gas and predeposited layer sources has been observed in metals, semiconductors, and ceramics as has surface enrichment of Cr by zone refinement of stainless steel. Rapid solidification after melting often results in the formation of nonequilibrium phases, including amorphous materials. Improved surface properties, including tribology and corrosion resistance, are observed in these materials.

  8. The Excimer Laser: Its Impact on Science and Industry

    Science.gov (United States)

    Basting, Dirk

    2010-03-01

    After the laser was demonstrated in 1960, 15 years were required to develop a practical method for extending laser emission into the UV: the Excimer laser. This historical review will describe the challenges with the new medium and provide an insight into the technological achievements. In the transition from Science to Industry it will be shown how start-ups successfully commercialized laboratory prototypes. The pioneers in this rapidly expanding field will be identified and the influence of government-funded research as well as the role of venture capital will be discussed. In scientific applications, the fields of photochemistry and material research were particularly stimulated by the advent of a reliable UV light source. Numerous industrial applications and worldwide research in novel applications were fueled In the early and mid 80's by progress in excimer laser performance and technology. The discovery of ablative photocomposition of polymer materials by Srinivasan at IBM opened the door to a multitude of important excimer applications. Micromachining with extreme precision with an excimer laser enabled the success of the inkjet printer business. Biological materials such as the human cornea can also be ``machined'' at 193nm, as proposed in 1983 by Trokel and Srinivasan. This provided the foundation of a new medical technology and an industry relying on the excimer laser to perform refractive surgery to correct vision Today, by far the largest use of the excimer laser is in photolithography to manufacture semiconductor chips, an application discovered by Jain at IBM in the early 80's. Moore's law of shrinking the size of the structure to multiply the number of transistors on a chip could not have held true for so long without the deep UV excimer laser as a light source. The presentation will conclude with comments on the most recent applications and latest market trends.

  9. Matrix metalloproteinase expression in excimer laser wounded rabbit corneas

    Science.gov (United States)

    Hahn, Taewon; Chamon, Wallace; Akova, Yonja; Stark, Walter J.; Stetler-Stevenson, William G.; Azar, Dimitri T.

    1994-06-01

    This study was performed to obtain information about matrix metalloproteinase (MMP) expression in excimer-wounded corneas and to determine whether MMPs expression correlates with the depth of the ablation. 6-mm excimer keratectomy (60 or 180 micrometers ) was performed using the 193-mm ArF excimer laser on 12 NZW rabbits. Corneas treated with mechanical epithelial debridement and untreated corneas served as controls. Rabbits were killed at 20 and 30 hr after laser ablation. Zymography after SDS extraction was performed on regenerated central epithelium and the central stroma to determine MMPs expression. We observed enzymatic activity of a 92 KDa band in the epithelium of excimer-ablated corneas but not in that following debridement wounds and untreated controls. The expression of the 92 KDa MMP was most pronounced with the deeper excimer ablation. A 72 KDa band of enzymatic activity present in the stroma of all treated and control eyes was also seen in the epithelium of excimer-ablated corneas. These proteolytic enzymes may play an important role in wound healing and remodelling after excimer keratectomy.

  10. Alkali-vapor laser-excimer pumped alkali laser

    International Nuclear Information System (INIS)

    Yue Desheng; Li Wenyu; Wang Hongyan; Yang Zining; Xu Xiaojun

    2012-01-01

    Based on the research internal and overseas, the principle of the excimer pumped alkali laser (XPAL) is explained, and the advantages and disadvantages of the XPAL are analyzed. Taking into consideration the difficulties that the diode pumped alkali laser (DPAL) meets on its development, the ability to solve or avoid these difficulties of XPAL is also analyzed. By summing up the achievements of the XPAL, the possible further prospect is proposed. The XPAL is of possibility to improve the performance of the DPAL. (authors)

  11. Latest result of PRK with excimer laser

    Science.gov (United States)

    Okamoto, Shinseiro; Okamoto, Michika

    1996-05-01

    We have in the last two years, performed PRK operation on over 300 human myopic eyes using ArF excimer laser with a Summit 'Omnimed' machine. For the initial 53 myopic eyes we treated, results were very good for those with correction less than minus 6 diopters. However, as previously reported, we also witnessed some regression for those eyes exceeding correction of more than minus 6 diopters. To counter such ill results of PRK we devised and suggested many new procedures for PRK with very good results. One such invention is the 'Okamoto-type' cooling machine for the cornea which reduces and stabilizes cornea temperature at 0 degrees Celsius while simultaneously bathing the cornea with special cooling fluid. After the operation, EGF, fibronectin and hexapeptide were administered using eyedrops. Soft contact lenses were used to protect the cornea, improve delivery of medication to the operated area, prevent infection and inflammation and also promote uniform and faster ephiterium regrowth. We were able to document very good post-operative results using this method, thereby giving us strong assurance that we have reached a significant milestone in PRK operation. Our report today covers post operative results of the 52 eyes we operated on and tracked for more than one year.

  12. Overview on the high power excimer laser technology

    Science.gov (United States)

    Liu, Jingru

    2013-05-01

    High power excimer laser has essential applications in the fields of high energy density physics, inertial fusion energy and industry owing to its advantages such as short wavelength, high gain, wide bandwidth, energy scalable and repetition operating ability. This overview is aimed at an introduction and evaluation of enormous endeavor of the international high power excimer laser community in the last 30 years. The main technologies of high power excimer laser are reviewed, which include the pumping source technology, angular multiplexing and pulse compressing, beam-smoothing and homogenous irradiation, high efficiency and repetitive operation et al. A high power XeCl laser system developed in NINT of China is described in detail.

  13. Optical design of high power excimer laser system

    International Nuclear Information System (INIS)

    Zhang Yongsheng; Zhao Jun; Ma Lianying; Yi Aiping; Liu Jingru

    2011-01-01

    Image relay and angular multiplexing,which should be considered together in the design of high power excimer laser system, is reviewed. It's important to select proper illumination setup and laser beam shaping techniques. Given the complex and special angular multiplexing scheme in high power excimer laser systems, some detailed conceptual layout schemes are given in the paper. After a brief description of lens array and reflective telescope objective, which combine the incoming beams to a common focus, a new schematic layout which uses the final targeting optics and one optical delay line array, to realize multiplexing and de-multiplexing simultaneously is first proposed in the paper. (authors)

  14. Excimer laser ablation of the cornea

    Science.gov (United States)

    Pettit, George H.; Ediger, Marwood N.; Weiblinger, Richard P.

    1995-03-01

    Pulsed ultraviolet laser ablation is being extensively investigated clinically to reshape the optical surface of the eye and correct vision defects. Current knowledge of the laser/tissue interaction and the present state of the clinical evaluation are reviewed. In addition, the principal findings of internal Food and Drug Administration research are described in some detail, including a risk assessment of the laser-induced-fluorescence and measurement of the nonlinear optical properties of cornea during the intense UV irradiation. Finally, a survey is presented of the alternative laser technologies being explored for this ophthalmic application.

  15. Advances in 193 nm excimer lasers for mass spectrometry applications

    Science.gov (United States)

    Delmdahl, Ralph; Esser, Hans-Gerd; Bonati, Guido

    2016-03-01

    Ongoing progress in mass analysis applications such as laser ablation inductively coupled mass spectrometry of solid samples and ultraviolet photoionization mediated sequencing of peptides and proteins is to a large extent driven by ultrashort wavelength excimer lasers at 193 nm. This paper will introduce the latest improvements achieved in the development of compact high repetition rate excimer lasers and elaborate on the impact on mass spectrometry instrumentation. Various performance and lifetime measurements obtained in a long-term endurance test over the course of 18 months will be shown and discussed in view of the laser source requirements of different mass spectrometry tasks. These sampling type applications are served by excimer lasers delivering pulsed 193 nm output of several mJ as well as fast repetition rates which are already approaching one Kilohertz. In order to open up the pathway from the laboratory to broader market industrial use, sufficient component lifetimes and long-term stable performance behavior have to be ensured. The obtained long-term results which will be presented are based on diverse 193 nm excimer laser tube improvements aiming at e.g. optimizing the gas flow dynamics and have extended the operational life the laser tube for the first time over several billion pulses even under high duty-cycle conditions.

  16. Modification of BSCCO surface by excimer laser annealing

    International Nuclear Information System (INIS)

    Ibi, A.; Akitsu, T.; Matsuzawa, H.

    2002-01-01

    Irradiation of Kr-F excimer laser onto the BSCCO calcined pellets changed their surface to be amorphous. SEM micrographs showed that sintering of the irradiated pellets recrystallized the surface layer and much reduced the intergrain gaps as compared with only sintered pellets, whereas the internal structure of the irradiated pellets remained unchanged. This processing made the surface-layer grains be tightly connected, resulting in the higher critical temperature than the conventionally sintered samples. We can say that excimer laser annealing process is a novel scheme to reduce the surface weak-link of the high Tc superconductors. (author)

  17. Treatment of onychomycosis using radiation of excimer laser

    Czech Academy of Sciences Publication Activity Database

    Urzová, J.; Jelínek, Miroslav; Mikšovský, Jan; Kymplová, J.

    2013-01-01

    Roč. 647, JAN (2013), s. 636-641 ISSN 1022-6680 R&D Projects: GA MŠk LD12069 Institutional support: RVO:68378271 Keywords : excimer laser * UV-C radiation * nails * onychomycosis Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. 308-nm excimer laser for the treatment of alopecia areata.

    Science.gov (United States)

    Al-Mutairi, Nawaf

    2007-12-01

    Alopecia areata is loss of hair from localized or diffuse areas of hair-bearing area of the skin. Recently there are reports of efficacy of the 308-nm excimer radiation for this condition. To study the effect of the 308-nm excimer laser in the treatment of alopecia areata. Eighteen patients with 42 recalcitrant patches (including 1 adult with alopecia totalis) were enrolled in this study. The lesions were treated with the 308-nm excimer laser twice a week for a period of 12 weeks; one lesion on each patient was left as a control for comparison. There were 7 males and 11 females in this study. Regrowth of hair was observed in 17 (41.5%) patches. Thirteen of the 18 lesions in scalp showed a complete regrowth of hair. The extremity regions failed to show a response. Atopic diatheses had an unfavorable effect on the outcome in our patients. The 308-nm excimer laser is an effective therapeutic option for patchy alopecia areata of the scalp and for some cases with patchy alopecia areata of the beard area. It does not work for patchy alopecia areata of the extremities.

  19. Collagen crosslinking for ectasia following PRK performed in excimer laser-assisted keratoplasty for keratoconus.

    Science.gov (United States)

    Spadea, Leopoldo

    2012-01-01

    To report the results of corneal collagen crosslinking (CXL) in a patient with corneal ectasia developed after excimer laser-assisted lamellar keratoplasty for keratoconus and a secondary photorefractive keratectomy (PRK) for residual refractive error. A 33-year-old woman, who had originally been treated for keratoconus in the right eye by excimer laser-assisted lamellar keratoplasty, subsequently had her residual ametropia treated by topographically guided, transepithelial excimer laser PRK. Five years after PRK, the patient developed corneal ectasia showing concomitant visual changes of best spectacle-corrected visual acuity (BSCVA) reduced to 20/33 with a refraction of -6.00 +6.00 × 30. The minimum corneal thickness at the ectasia apex was 406 µm. A treatment of riboflavin-UVA-induced corneal CXL was performed on the right eye. Two years after the CXL treatment, the right eye improved to 20/20 BSCVA with a refraction of plano +1.00 × 50 while exhibiting a clear lamellar graft. Corneal CXL provided safe and effective management of ectasia developed after excimer laser-assisted lamellar keratoplasty and PRK.

  20. Application of optical tweezers and excimer laser to study protoplast fusion

    Science.gov (United States)

    Kantawang, Titirat; Samipak, Sompid; Limtrakul, Jumras; Chattham, Nattaporn

    2015-07-01

    Protoplast fusion is a physical phenomenon that two protoplasts come in contact and fuse together. Doing so, it is possible to combine specific genes from one protoplast to another during fusion such as drought resistance and disease resistance. There are a few possible methods to induce protoplast fusion, for example, electrofusion and chemical fusion. In this study, chemical fusion was performed with laser applied as an external force to enhance rate of fusion and observed under a microscope. Optical tweezers (1064 nm with 100X objective N.A. 1.3) and excimer laser (308 nm LMU-40X-UVB objective) were set with a Nikon Ti-U inverted microscope. Samples were prepared by soaking in hypertonic solution in order to induce cell plasmolysis. Elodea Canadensis and Allium cepa plasmolysed leaves were cut and observed under microscope. Concentration of solution was varied to induce difference turgor pressures on protoplasts pushing at cell wall. Free protoplasts in solution were trapped by optical tweezers to study the effect of Polyethylene glycol (PEG) solution. PEG was diluted by Ca+ solution during the process to induced protoplast cell contact and fusion. Possibility of protoplast fusion by excimer laser was investigated and found possible. Here we report a novel tool for plant cell fusion using excimer laser. Plant growth after cell fusion is currently conducted.

  1. Triggering Excimer Lasers by Photoionization from Corona Discharges

    Science.gov (United States)

    Xiong, Zhongmin; Duffey, Thomas; Brown, Daniel; Kushner, Mark

    2009-10-01

    High repetition rate ArF (192 nm) excimer lasers are used for photolithography sources in microelectronics fabrication. In highly attaching gas mixtures, preionization is critical to obtaining stable, reproducible glow discharges. Photoionization from a separate corona discharge is one technique for preionization which triggers the subsequent electron avalanche between the main electrodes. Photoionization triggering of an ArF excimer laser sustained in multi-atmosphere Ne/Ar/F2/Xe gas mixtures has been investigated using a 2-dimensional plasma hydrodynamics model including radiation transport. Continuity equations for charged and neutral species, and Poisson's equation are solved coincident with the electron temperature with transport coefficients obtained from solutions of Boltzmann's equation. Photoionizing radiation is produced by a surface discharge which propagates along a corona-bar located adjacent to the discharge electrodes. The consequences of pulse power waveform, corona bar location, capacitance and gas mixture on uniformity, symmetry and gain of the avalanche discharge will be discussed.

  2. Nebulae at keratoconus--the result after excimer laser removal.

    Science.gov (United States)

    Fagerholm, P; Fitzsimmons, T; Ohman, L; Orndahl, M

    1993-12-01

    Ten patients underwent excimer laser ablation due to nebula formation at keratoconus. The nebulae interfered significantly with contact lens fit or wearing time. The mean follow-up time in these patients was 16.5 months. Following surgery all patients could be successfully fitted with a contact lens and thereby obtain good visual acuity. Furthermore, contact lens wearing time was 8 hours or more in all cases. In 2 patients the nebulae recurred but were successfully retreated.

  3. Subjective results of excimer laser correction of myopia. Review

    Directory of Open Access Journals (Sweden)

    V. N. Trubilin

    2012-01-01

    Full Text Available In review presents data of various authors regarding the subjective results excimer laser correction of myopia by LASIK. It was revealed that a group of patients with a high degree of dissatisfaction amounts to 4.6% of the total in all studies. High subjective results are confirmed by the positive dynamics of the «quality of life» of the patient.

  4. Myopic keratomileusis by excimer laser on a lathe.

    Science.gov (United States)

    Ganem, S; Aron-Rosa, D; Gross, M; Rosolen, S

    1994-01-01

    We designed an excimer laser keratomileusis delivery system to increase the regularity of the refractive cut surface and allow greater precision in the level and shape of the ablated zone. A parallel faced corneal disc was produced by microkeratectomy from six human eyes and surgical keratectomy in 12 beagle corneas. A 193-nanometer excimer laser that was used to project an oval beam onto the corneal disc was rotated on a flat surface to ensure overlapping of the ovally ablated areas between pulses. Electron microscopy of eye bank lenticules demonstrated a circular smooth regularly concave ablation zone. Histological examination of nine clear corneas confirmed thinning of the stroma without fibroblastic reaction and no epithelial hypertrophy. Mean preoperative corneal power of 43.15 +/- 2.18 decreased postoperatively to 33.61 +/- 2.34. The new technique of excimer laser keratomileusis has the advantage of a cut surface smoother and the clear zone is devoid of the stepwise concavity and irregularity seen in diaphragm based photoablation delivery systems.

  5. Assessment of the suitability of excimer lasers in treating onychomycosis

    International Nuclear Information System (INIS)

    Kymplová, Jaroslava; Dušek, Karel; Jelínek, Miroslav; Urzová, Jana; Mikšovský, Jan; Bauerová, Lenka

    2014-01-01

    Since it is known that UV-C radiation kills fungus, we wanted to verify the hypothesis that the use of excimer laser could be an alternative method for treating onychomycosis - nail fungus. The aim of the first stage of this work was to determine the transmission, reflection and absorption of nails. In the following stage we focused on irradiation of fungi. Our final task is to assess whether it is possible to determine the parameters of radiation (a total dose,a dose per pulse frequency, a repetition rate, a number of pulses) for which the elimination of fungi would be the most effective but without damaging the nail and soft tissue underneath it. The results so far have showed that UV-C radiation does not pass through a fingernail to such an extent that it could damage the soft tissue beneath it. Fungi are destroyed by the application of only small doses of radiation using the excimer laser. Additional measurements will be required to determine the modulation parameters of the excimer laser radiation for the treatment of onychomycosis.

  6. Automatic alignment of double optical paths in excimer laser amplifier

    Science.gov (United States)

    Wang, Dahui; Zhao, Xueqing; Hua, Hengqi; Zhang, Yongsheng; Hu, Yun; Yi, Aiping; Zhao, Jun

    2013-05-01

    A kind of beam automatic alignment method used for double paths amplification in the electron pumped excimer laser system is demonstrated. In this way, the beams from the amplifiers can be transferred along the designated direction and accordingly irradiate on the target with high stabilization and accuracy. However, owing to nonexistence of natural alignment references in excimer laser amplifiers, two cross-hairs structure is used to align the beams. Here, one crosshair put into the input beam is regarded as the near-field reference while the other put into output beam is regarded as the far-field reference. The two cross-hairs are transmitted onto Charge Coupled Devices (CCD) by image-relaying structures separately. The errors between intersection points of two cross-talk images and centroid coordinates of actual beam are recorded automatically and sent to closed loop feedback control mechanism. Negative feedback keeps running until preset accuracy is reached. On the basis of above-mentioned design, the alignment optical path is built and the software is compiled, whereafter the experiment of double paths automatic alignment in electron pumped excimer laser amplifier is carried through. Meanwhile, the related influencing factors and the alignment precision are analyzed. Experimental results indicate that the alignment system can achieve the aiming direction of automatic aligning beams in short time. The analysis shows that the accuracy of alignment system is 0.63μrad and the beam maximum restoration error is 13.75μm. Furthermore, the bigger distance between the two cross-hairs, the higher precision of the system is. Therefore, the automatic alignment system has been used in angular multiplexing excimer Main Oscillation Power Amplification (MOPA) system and can satisfy the requirement of beam alignment precision on the whole.

  7. Levels of interleukin-6 in tears before and after excimer laser treatment

    OpenAIRE

    Resan Mirko; Stanojević Ivan; Petković-Ćurčin Aleksandra; Pajić Bojan; Vojvodić Danilo

    2015-01-01

    Background/Aim. Immune response and consequent inflammatory process which originate on ocular surface after a trauma are mediated by cytokines. Photoablation of corneal stroma performed by excimer laser causes surgically induced trauma. Interleukin-6 (IL-6) is mostly known as a proinflammatory cytokine. However, it also has regenerative and anti-inflammatory effects. It is supposed that this cytokine is likely to play a significant role in the process of co...

  8. Pulse repetition frequency effects in a high average power x-ray preionized excimer laser

    International Nuclear Information System (INIS)

    Fontaine, B.; Forestier, B.; Delaporte, P.; Canarelli, P.

    1989-01-01

    Experimental study of waves damping in a high repetition rate excimer laser is undertaken. Excitation of laser active medium in a subsonic loop is achieved by means of a classical discharge, through transfer capacitors. The discharge stability is controlled by a wire ion plasma (w.i.p.) X-rays gun. The strong acoustic waves induced by the active medium excitation may lead to a decrease, at high PRF, of the energy per pulse. First results of the influence of a damping of induced density perturbations between two successive pulses are presented

  9. Effect of volatile compounds on excimer laser power delivery.

    Science.gov (United States)

    Van Horn, Stewart D; Hovanesian, John A; Maloney, Robert K

    2002-01-01

    To determine whether vapors from perfume, hairspray, oil-based paint, or water-based paint affect excimer laser beam power delivery at the corneal surface. We measured the power delivery of an Apex Plus laser before, during, and after exposure to vapors from the following volatile compounds: three types of perfume, hair spray, an oil-based paint, and a water-based paint. A digital calorimeter was used to measure the steady-state beam power of the laser during laser discharge at the corneal plane. Multiple trials were run with each compound, and the change in laser energy over time was examined to determine if any of the compounds caused degradation of the laser optics. The presence of a volatile compound in the room caused no change in mean laser energy in comparison to before and after the compound was present. However, perfumes caused a progressive decline in laser beam power throughout the trials. Controlling for this progressive decline, there was no significant difference from perfume to perfume. None of the compounds tested caused a decline in laser beam power while present in the room. However, the presence of any perfume caused a deterioration in beam power over time, suggesting a degradation of the laser optics for all perfumes. Laser centers should consider advising their patients and staff to not wear perfumes in the laser suite.

  10. Excimer laser superficial keratectomy for proud nebulae in keratoconus.

    Science.gov (United States)

    Moodaley, L; Liu, C; Woodward, E G; O'Brart, D; Muir, M K; Buckley, R

    1994-06-01

    Contact lens intolerance in keratoconus may be due to the formation of a proud nebula at or near the apex of the cone. Excimer laser superficial keratectomy was performed as an outpatients with proud nebulae as treatment patients with proud nebulae as treatment for their contact lens intolerance. The mean period of contact lens wear before the development of intolerance was 13.4 years (range 2 to 27 years). Following the development of intolerance, three patients abandoned contact lens wear in the affected eye while the remainder experienced a reduction in comfortable wearing time (mean = 3.75 hours; range: 0-14 hours). All patients had good potential Snellen visual acuity with a contact lens of 6/9 (nine eyes) and 6/12 (one eye). The proud nebulae were directly ablated with a 193 nm ArF excimer laser using a 1 mm diameter beam. Between 100-150 pulses were sufficient to ablate the raised area. Patients experienced no pain during the procedure and reported minimal discomfort postoperatively. In all cases flattening of the proud nebulae was achieved. Seven patients were able to resume regular contact lens wear (mean wearing time = 10.17 hours; range 8 to 16 hours). In three patients, resumption of contact lens wear was unsuccessful because of cone steepness. All patients achieved postoperative Snellen visual acuity of 6/12 or better with a contact lens. Four patients experienced a loss of one line in Snellen acuity. The mean follow up period was 8.3 months (range 2 to 17 months). Excimer laser superficial keratectomy is a useful technique for the treatment of contact lens intolerance caused by proud nebulae in patients with keratoconus. Penetrating keratoplasty is thus avoided.

  11. Corneal aldehyde dehydrogenase and glutathione S-transferase activity after excimer laser keratectomy in guinea pigs.

    Science.gov (United States)

    Bilgihan, K; Bilgihan, A; Hasanreisoğlu, B; Turkozkan, N

    1998-03-01

    The free radical balance of the eye may be changed by excimer laser keratectomy. Previous studies have demonstrated that excimer laser keratectomy increases the corneal temperature, decreases the superoxide dismutase activity of the aqueous, and induces lipid peroxidation in the superficial corneal stroma. Aldehyde dehydrogenase (ALDH) and glutathione S-transferase (GST) are known to play an important role in corneal metabolism, particularly in detoxification of aldehydes, which are generated from free radical reactions. In three groups of guinea pigs mechanical corneal de-epithelialisation was performed in group I, superficial corneal photoablation in group II, and deep corneal photoablation in group III, and the corneal ALDH and GST activities measured after 48 hours. The mean ALDH and GST activities of group I and II showed no differences compared with the controls (p > 0.05). The corneal ALDH activities were found to be significantly decreased (p < 0.05) and GST activities increased (p < 0.05) in group III. These results suggest that excimer laser treatment of high myopia may change the ALDH and GST activities, metabolism, and free radical balance of the cornea.

  12. Excimer laser processing of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Folkes, J.A.; Shibata, K.

    1994-01-01

    The effect of the excimer laser on the surface of Ti-6Al-4V is reported. Particular concentration is given to surface modification for potential materials processing applications. Results showed that: (1) there is an optimum energy for smoothing titanium; (2) at this energy density increasing the number of pulses has some, but not a significant, effect on the smoothing process; and (3) relatively smooth surfaces could be achieved at higher energy densities if the sample was processed in a helium atmosphere. Other typical surface modifications and features are also reported, including the effect of different gases on the process

  13. Keratomodelling with low-intensity ultraviolet radiation of excimer laser

    International Nuclear Information System (INIS)

    Vitrishchak, I.B.; Vorontsov, V.V.; Murzin, A.G.; Polikarpov, S.S.; Soms, L.N.

    1990-01-01

    A study was made on possibility of keratomodelling with low-intensive UV-radiation of excimer laser with subablation energy density in a pulse. Model specimens of polymers and cornea tissue were used. It is shown that the range of threshold energy density in a pulse expands with increase of UV-radiation wave length and contracts with increase of pulse repetition frequency. This range appeared to be different for polymers and cornea tissue. It was revealed that cornea tissue represented a complex high-molecular bipolymer with high water content

  14. Scattered UV irradiation during VISX excimer laser keratorefractive surgery.

    Science.gov (United States)

    Hope, R J; Weber, E D; Bower, K S; Pasternak, J P; Sliney, D H

    2008-04-01

    To evaluate the potential occupational health hazards associated with scattered ultraviolet (UV) radiation during photorefractive keratectomy (PRK) using the VISX Star S3 excimer laser. The Laser Vision Center, National Naval Medical Center, Bethesda, Maryland, USA. Intraoperative radiometric measurements were made with the Ophir Power/Energy Meter (LaserStar Model PD-10 with silicon detector) during PRK treatments as well as during required calibration procedures at a distance of 20.3 cm from the left cornea. These measurements were evaluated using a worst-case scenario for exposure, and then compared with the American Conference of Governmental Industrial Hygeinists (ACGIH) Threshold Value Limits (TVL) to perform a risk/hazard analysis. During the PRK procedures, the highest measured value was 248.4 nJ/pulse. During the calibration procedures, the highest measured UV scattered radiation level was 149.6 nJ/pulse. The maximum treatment time was 52 seconds. Using a worst-case scenario in which all treatments used the maximum power and time, the total energy per eye treated was 0.132 mJ/cm2 and the total UV radiation at close range (80 cm from the treated eye) was 0.0085 mJ/cm2. With a workload of 20 patients, the total occupational exposure at 80 cm to actinic UV radiation in an 8-hour period would be 0.425 mJ/cm2. The scattered actinic UV laser radiation from the VISX Star S3 excimer laser did not exceed occupational exposure limits during a busy 8-hour workday, provided that operating room personnel were at least 80 cm from the treated eye. While the use of protective eyewear is always prudent, this study demonstrates that the trace amounts of scattered laser emissions produced by this laser do not pose a serious health risk even without the use of protective eyewear.

  15. Laser dentistry: A new application of excimer laser in root canal therapy

    International Nuclear Information System (INIS)

    Pini, R.; Salimbeni, R.; Vannini, M.; Barone, R.; Clauser, C.

    1989-01-01

    We report the first study of the application of excimer lasers in dentistry for the treatment of dental root canals. High-energy ultraviolet (UV) radiation emitted by an XeCl excimer laser (308 nm) and delivered through suitable optical fibers can be used to remove residual organic tissue from the canals. To this aim, UV ablation thresholds of dental tissues have been measured, showing a preferential etching of infiltrated dentin in respect to healthy dentin, at laser fluences of 0.5-1.5 J/cm 2 . This technique has been tested on extracted tooth samples, simulating a clinical procedure. Fibers of decreasing core diameters have been used to treat different sections of the root canal down to its apical portion, resulting in an effective, easy, and fast cleaning action. Possible advantages of excimer laser clinical applications in respect to usual procedures are also discussed

  16. Excimer laser beam delivery systems for medical applications

    Science.gov (United States)

    Kubo, Uichi; Hashishin, Yuichi; Okada, Kazuyuki; Tanaka, Hiroyuki

    1993-05-01

    We have been doing the basic experiments of UV laser beams and biotissue interaction with both KrF and XeCl lasers. However, the conventional optical fiber can not be available for power UV beams. So we have been investigating about UV power beam delivery systems. These experiments carry on with the same elements doped quartz fibers and the hollow tube. The doped elements are OH ion, chlorine and fluorine. In our latest work, we have tried ArF excimer laser and biotissue interactions, and the beam delivery experiments. From our experimental results, we found that the ArF laser beam has high incision ability for hard biotissue. For example, in the case of the cow's bone incision, the incision depth by ArF laser was ca.15 times of KrF laser. Therefore, ArF laser would be expected to harden biotissue therapy as non-thermal method. However, its beam delivery is difficult to work in this time. We will develop ArF laser beam delivery systems.

  17. Laser drilling of metals with a XeCl excimer laser

    NARCIS (Netherlands)

    Schoonderbeek, A.

    2005-01-01

    This thesis is about laser drilling with a unique excimer laser with a nearly diffraction-limited beam and relatively long optical pulse duration of 175 ns. The combination of high processing speed and high processing quality suitable for industrial applications can be obtained because the excellent

  18. High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review of the ...... line marking with TEA-CO2 laser of high speed canning lines. The second one is manufactured for marking or microdrilling with excimer laser....

  19. Fabrication of SERS Active Surface on Polyimide Sample by Excimer Laser Irradiation

    Directory of Open Access Journals (Sweden)

    T. Csizmadia

    2014-01-01

    Full Text Available A possible application of excimer laser irradiation for the preparation of surface enhanced Raman spectroscopy (SERS substrate is demonstrated. A polyimide foil of 125 μm thickness was irradiated by 240 pulses of focused ArF excimer laser beam (λ = 193 nm, FWHM = 20 ns. The applied fluence was varied between 40 and 80 mJ/cm2. After laser processing, the sample was coated with 40 nm silver by PLD in order to create a conducting layer required for the SERS application. The SERS activity of the samples was tested by Raman microscopy. The Raman spectra of Rhodamine 6G aqueous solution (c=10−3 mol/dm3 were collected from the patterned and metalized areas. For areas prepared at 40–60 mJ/cm2 laser fluences, the measured Raman intensities have shown a linear dependence on the applied laser fluence, while above 60 mJ/cm2 saturation was observed. The morphology of the SERS active surface areas was investigated by scanning electron microscopy. Finite element modeling was performed in order to simulate the laser-absorption induced heating of the polyimide foil. The simulation resulted in the temporal and spatial distribution of the estimated temperature in the irradiated polyimide sample, which are important for understanding the structure formation process.

  20. Boron distribution in silicon after multiple pulse excimer laser annealing

    International Nuclear Information System (INIS)

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Italia, M.; Privitera, V.; Fortunato, G.; Cuscuna, M.; Mariucci, L.

    2005-01-01

    We have studied B redistribution in Si after excimer laser annealing (ELA) with multiple laser pulses. B was implanted with energies of 1 and 10 keV and doses of 1x10 14 and 1x10 15 cm -2 . ELA with the number of pulses from 1 to 100 was performed at room temperature and 450 deg. C in vacuum. Irrespective of the implantation parameters and the ELA conditions used, a pile-up in the B concentration is observed near the maximum melting depth after ten pulses of ELA. Moreover, a detailed study has revealed that B accumulates at the maximum melt depth gradually with the number of ELA pulses. Besides, an increase in the carrier concentration is observed at the maximum melt depth, suggesting electrical activity of the accumulated B. Formation of Si-B complexes and vacancy accumulation during multiple ELA are discussed as possible mechanisms for the B build-up

  1. The application of excimer lasers for corneal sculpturing

    International Nuclear Information System (INIS)

    King, M.C.

    1990-01-01

    Of the broad selection of lasers available for surgery, the argon fluoride excimer laser offers a set of attributes that make it uniquely suited for the removal of corneal tissue. With ultraviolet radiation at 193mm, the energy of an individual photon (6.3 electron volts) is sufficient to break bonds in protein molecules without generating molecular vibration (heat). A single laser pulse is capable of removing 0.25 microns of corneal tissue over a well defined area 80 mm 2 in extent. This excision with a lateral precision to a fraction of a micron causes no discernible damage to neighboring cells. The smooth surface left after the tissue is removed promotes a quick and predictable regrowth of the epithelium. The penetration of radiation into the underlying tissue is the order of a micron so there is no potential harm to the lens or retinal tissue. Insignificant mutagenesis or unscheduled DNA synthesis has been detected as a result of tissue irradiation at this wavelength. In the past few years major progress has been made towards developing ophthalmic procedures which utilize the unique properties of this laser. To date there are FDA IDE's (Investigational Device Exemptions) for the following procedures: Photorefractive Keratectomy (PRK) or corneal reshaping for correcting near-sightedness, far-sightedness and astigmatism without the need for eye glasses, contact lenses or conventional refractive surgery (Radial Keratotomy); Partial Excimer Trabeculectomy for relieving the pressure build-up caused by glaucoma; T-Excisons for reducing astigmatism; Myopic Keratomileusis (MKM) for the refractive correction of severe myopia; superficial Keratectomy (corneal smoothing) for treating various corneal scars, dystrophies, recurrent corneal erosion etc. In this paper the fundamentals of beam tissue interaction at 193nm will be discussed

  2. The effect of microarc oxidation and excimer laser processing on the microstructure and corrosion resistance of Zr–1Nb alloy

    International Nuclear Information System (INIS)

    Yang, Jiaoxi; Wang, Xin; Wen, Qiang; Wang, Xibing; Wang, Rongshan; Zhang, Yanwei; Xue, Wenbin

    2015-01-01

    The main purpose of this research was to investigate the effect of microarc oxidation (MAO) and excimer laser processing on the corrosion resistance of Zr–1Nb alloy in service environment. The pre-oxide film was fabricated on the surface of Zr–1Nb cladding tubes by MAO processing, and then subjected to KrF excimer laser irradiation. The surface morphology of the pre-oxide film was observed using a scanning electron microscope; phase compositions and quantities were determined using an X-ray diffraction; surface roughness was determined using a profilometer; and thermal expansion coefficient was measured using a dilatometer. Autoclave experiments were conducted for 94 days in an aqueous condition of 360 °C under 18.6 MPa in 0.01 mol/L LiOH solutions. The results showed that MAO + laser treatment resulted in a significant increase in the corrosion resistance of Zr–1Nb cladding tubes at high temperatures, because laser melting and etching could lead to a reduction in surface roughness and an increase in compactness of the pre-oxide film, and laser processing could promote the transformation of m-ZrO 2 phase to t-ZrO 2 phase. The best corrosion resistance was obtained when the pulse energy was 500 mJ, scanning speed was 0.13 mm/s, and pulse number was 2400. - Highlights: • Pre-oxide film was fabricated on Zr–1Nb cladding tube by MAO+ excimer laser processing. • Excimer laser processing induced the transformation of m-ZrO 2 to t-ZrO 2 . • The Rietveld quantitative analysis of the pre-oxide film was made. • We investigated the high temperature corrosion and corrosion mechanism of the oxide film. • The parameters of MAO+ excimer laser processing were optimized.

  3. The effect of microarc oxidation and excimer laser processing on the microstructure and corrosion resistance of Zr–1Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jiaoxi, E-mail: yangjiaoxi@bjut.edu.cn [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Wang, Xin; Wen, Qiang; Wang, Xibing [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Wang, Rongshan; Zhang, Yanwei [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Xue, Wenbin [College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2015-12-15

    The main purpose of this research was to investigate the effect of microarc oxidation (MAO) and excimer laser processing on the corrosion resistance of Zr–1Nb alloy in service environment. The pre-oxide film was fabricated on the surface of Zr–1Nb cladding tubes by MAO processing, and then subjected to KrF excimer laser irradiation. The surface morphology of the pre-oxide film was observed using a scanning electron microscope; phase compositions and quantities were determined using an X-ray diffraction; surface roughness was determined using a profilometer; and thermal expansion coefficient was measured using a dilatometer. Autoclave experiments were conducted for 94 days in an aqueous condition of 360 °C under 18.6 MPa in 0.01 mol/L LiOH solutions. The results showed that MAO + laser treatment resulted in a significant increase in the corrosion resistance of Zr–1Nb cladding tubes at high temperatures, because laser melting and etching could lead to a reduction in surface roughness and an increase in compactness of the pre-oxide film, and laser processing could promote the transformation of m-ZrO{sub 2} phase to t-ZrO{sub 2} phase. The best corrosion resistance was obtained when the pulse energy was 500 mJ, scanning speed was 0.13 mm/s, and pulse number was 2400. - Highlights: • Pre-oxide film was fabricated on Zr–1Nb cladding tube by MAO+ excimer laser processing. • Excimer laser processing induced the transformation of m-ZrO{sub 2} to t-ZrO{sub 2}. • The Rietveld quantitative analysis of the pre-oxide film was made. • We investigated the high temperature corrosion and corrosion mechanism of the oxide film. • The parameters of MAO+ excimer laser processing were optimized.

  4. Outcomes for Myopic LASIK With the MEL 90 excimer laser.

    Science.gov (United States)

    Reinstein, Dan Z; Carp, Glenn I; Lewis, Tariq A; Archer, Timothy J; Gobbe, Marine

    2015-05-01

    To evaluate the visual outcomes of myopic LASIK performed with the MEL 90 excimer laser (Carl Zeiss Meditec AG, Jena, Germany) using the Triple-A profile with a 500-Hz pulse rate. Retrospective analysis of the first 286 myopic LASIK procedures (147 patients) by two experienced surgeons in which the VisuMax femtosecond laser and MEL 90 excimer laser (Carl Zeiss Meditec) were used following a standardized surgical technique. Inclusion criteria were preoperative spherical equivalent refraction (SEQ) up to -10.38 diopters (D), cylinder up to 5.00 D, and corrected distance visual acuity (CDVA) of 20/25 or better. No nomogram adjustments were made. Patients were observed for 3 months. Flap thickness was between 80 and 110 µm and optical zone was between 6 and 7 mm. Standard outcomes analysis was performed. Preoperatively, mean SEQ was -3.83 ± 1.83 D (range: -0.13 to -10.38 D) and mean cylinder was -0.94 ± 0.86 D (range: 0.00 to -5.00 D). Mean age was 36.4 years (range: 18.2 to 74.1 years) with 50% female patients. Of this population, 138 eyes were treated by one surgeon and 148 eyes by another. The mean predictability of SEQ was -0.13 ± 0.34 D (range: -1.00 to +1.00 D). Postoperative SEQ was ± 0.50 D in 88% and ± 1.00 D in 100% of eyes. Preoperative CDVA was 20/20 or better in 97% of eyes. Postoperative uncorrected distance visual acuity was 20/20 or better in 92% and 20/25 or better in 99% of eyes. One line of CDVA was lost in 6% of eyes and no eyes lost two or more lines. There was statistically significant improvement in mesopic contrast sensitivity (CSV-1000) at 3 (P = .021), 6, 12, and 18 (all P ≤.001) cycles per degree. The MEL 90 excimer laser using the Triple-A ablation profile with a 500-Hz pulse rate was found to achieve a small but real increase in contrast sensitivity and high efficacy for myopia up to -10.00 D and cylinder up to 5.00 D without the need for a nomogram adjustment. Copyright 2015, SLACK Incorporated.

  5. Combination treatment with excimer laser and narrowband UVB light in vitiligo patients.

    Science.gov (United States)

    Shin, Sungsik; Hann, Seung-Kyung; Oh, Sang Ho

    2016-01-01

    For the treatment of vitiligo, narrowband UVB (NBUVB) light is considered the most effective for nonsegmental vitiligo, while excimer laser treatment is commonly used for localized vitiligo. However, treatment areas may potentially be missed with excimer laser treatment. We aimed to evaluate the effect of combinational treatment with NBUVB light and excimer laser on vitiligo. All patients were first treated with NBUVB; excimer laser was then applied in conjunction with NBUVB phototherapy due to a slow response or no further improvement with continuous NBUVB treatment alone. To minimize adverse effects, a fixed dose of NBUVB was administered, and the dose of excimer laser was increased based on patient response. Among 80 patients, 54 patients showed responses after combination with excimer laser; however, 26 patients (32.5%) showed no remarkable change after combination therapy. Of the 26 patients who showed no further response, 12 patients (46.1%) presented with vitiligo on the acral areas, which are known to the least responsive sites. Our study suggests that combined treatment of NBUVB and excimer laser in vitiligo may enhance the treatment response without remarkable side effects, therefore might also increase the compliance of the patients to the treatment. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. FEM numerical analysis of excimer laser induced modification in alternating multi-layers of amorphous and nano-crystalline silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.es [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Martin, E. [Dpto. Mecanica, Maquinas, Motores Termicos y Fluidos, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Stefanov, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Alpuim, P. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Chiussi, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer nc-Si:H is a material with growing importance for a large-area of nano-electronic, photovoltaic or biomedical devices. Black-Right-Pointing-Pointer UV-ELA technique causes a rapid heating that provokes the H{sub 2} desorption from the Si surface and bulk material. Black-Right-Pointing-Pointer Next, diffusion of P doped nc-Si films and eventually, for high energy densities would be possible to reach the melting point. Black-Right-Pointing-Pointer These multilayer structures consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) films deposited on SiO{sub 2}. Black-Right-Pointing-Pointer To optimize parameters involved in this processing, FEM numerical analysis of multilayer structures have been performed. Black-Right-Pointing-Pointer The numerical results are compared with exhaustive characterization of the experimental results. - Abstract: UV excimer laser annealing (UV-ELA) is an alternative annealing process that, during the last few years, has gained enormous importance for the CMOS nano-electronic technologies, with the ability to provide films and alloys with electrical and optical properties to fit the desired device performance. The UV-ELA of amorphous (a-) and/or doped nano-crystalline (nc-) silicon films is based on the rapid (nanoseconds) formation of temperature profiles caused by laser radiation that is absorbed in the material and lead to crystallisation, diffusion in solid or even in liquid phase. To achieve the desired temperature profiles and to optimize the parameters involved in the processing of hydrogenated nanocrystalline silicon (nc-Si:H) films with the UV-ELA, a numerical analysis by finite element method (FEM) of a multilayer structure has been performed. The multilayer structures, consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) layers, deposited on a glass substrate, has also been experimentally analyzed. Temperature profiles caused by 193 nm radiation with 25

  7. FEM numerical analysis of excimer laser induced modification in alternating multi-layers of amorphous and nano-crystalline silicon films

    International Nuclear Information System (INIS)

    Conde, J.C.; Martín, E.; Stefanov, S.; Alpuim, P.; Chiussi, S.

    2012-01-01

    Highlights: ► nc-Si:H is a material with growing importance for a large-area of nano-electronic, photovoltaic or biomedical devices. ► UV-ELA technique causes a rapid heating that provokes the H 2 desorption from the Si surface and bulk material. ► Next, diffusion of P doped nc-Si films and eventually, for high energy densities would be possible to reach the melting point. ► These multilayer structures consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) films deposited on SiO 2 . ► To optimize parameters involved in this processing, FEM numerical analysis of multilayer structures have been performed. ► The numerical results are compared with exhaustive characterization of the experimental results. - Abstract: UV excimer laser annealing (UV-ELA) is an alternative annealing process that, during the last few years, has gained enormous importance for the CMOS nano-electronic technologies, with the ability to provide films and alloys with electrical and optical properties to fit the desired device performance. The UV-ELA of amorphous (a-) and/or doped nano-crystalline (nc-) silicon films is based on the rapid (nanoseconds) formation of temperature profiles caused by laser radiation that is absorbed in the material and lead to crystallisation, diffusion in solid or even in liquid phase. To achieve the desired temperature profiles and to optimize the parameters involved in the processing of hydrogenated nanocrystalline silicon (nc-Si:H) films with the UV-ELA, a numerical analysis by finite element method (FEM) of a multilayer structure has been performed. The multilayer structures, consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) layers, deposited on a glass substrate, has also been experimentally analyzed. Temperature profiles caused by 193 nm radiation with 25 ns pulse length and energy densities ranging from 50 mJ/cm 2 to 400 mJ/cm 2 have been calculated. Numerical results allowed us to estimate the dehydrogenation

  8. 3-D ASE calculation for high power output XeCl excimer lasers

    International Nuclear Information System (INIS)

    Tu Qinfen; Zhang Jianquan; Wu Baosheng

    1996-01-01

    The 3-dimensional ASE calculation for electron beam pumping XeCl excimer laser is presented by M-C method. In the model wall-reflected ASE is included. This calculation also includes non-saturable absorption and mirror that reflect ASE flux back into the active gain medium. Results show optimum scaling of injected flux. It can provide theoretical basis and experimental references for experiments on excimer lasers, and be extrapolated to any other type of laser

  9. Effect of excimer laser (Arf, 193 nm) on aqueous humor during photorefractive keratectomy biophysical and biochemical study

    International Nuclear Information System (INIS)

    Mahmoud, S.S.; Mahmoud, A.A.

    2004-01-01

    Ultraviolet light (193 nm) produced by an excimer laser has been used to produce precise tissue ablation with minimal thermal damage to adjacent tissue. The present study was designed to investigate the effect of excimer laser during photo refractive keratectomy (PRK) on aqueous humor constituents and also the effect of antioxidant enzyme superoxide dismutase (SOD)- applied topically- on these changes if exist. Five groups of schenchilla rabbits were involved in this study, where four groups underwent corneal stromal ablation using argon fluoride excimer laser (Ar F, 193 nm). Two of these four groups were treated with superoxide dismutase intra operatively. The fifth group was used as control one. The obtained results revealed depletion of aqueous humor ascorbate and glutathione contents. Aqueous humor refractive index, cholesterol, phospholipids, malondialdehyde (MDA) and total protein were measured. In conclusion, the excimer laser can induce changes in aqueous humor constituents during PRK. These changes lasted at least for 24 hours and as the time increased to 4 weeks, these changes became limited. The use of exogenous SOD seems to exert beneficial effect on aqueous humor refractive index and total protein

  10. Excimer laser annealing of shallow As and B doped layers

    International Nuclear Information System (INIS)

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; Magna, A. La; Privitera, V.; Camalleri, M.; Fortunato, G.; Mariucci, L.

    2004-01-01

    Excimer laser annealing (ELA) of As-, B- and BF 2 -implanted Si has been studied by secondary ion mass spectrometry (SIMS), spreading resistance probe (SRP) and transmission electron microscopy (TEM). The implantations have been performed in the energy range from 1 to 30 keV with doses of 10 15 -10 16 cm -2 . ELA has been carried out with the energy densities in the range of 600-1200 mJ/cm 2 and the number of laser pulses from 1 to 10. It is shown that ELA results in a more uniform dopant distribution over the doped region with a more abrupt profile edge as compared to those after rapid thermal annealing (RTA). Besides, in contrast to RTA, ELA demonstrates a highly confined annealing effect, where the distribution of dopants below the melting region is not affected. SRP measurements demonstrate almost complete activation of the implanted dopants after ELA, and TEM does not reveal extended defects in the ELA-treated samples. The depth of the doped layers, abruptness of the profiles and the total doping dose as a function of ELA energy density and number of laser pulses are investigated. Computer simulations of ELA show a good agreement with the experimental data

  11. Fabrication of biosynthetic vascular prostheses by 193-nm excimer laser radiation

    Science.gov (United States)

    Husinsky, Wolfgang; Csek, Ch.; Bartel, A.; Grabenwoeger, M.; Fitzal, F.; Wolner, Ernst

    1998-05-01

    This study was undertaken to investigate the feasibility of transmural capillary ingrowth into the inner surface of biosynthetic vascular prostheses (OmniflowTM) through perforations created by an excimer-laser, thus inducing an endothelial cell coverage. The biosynthetic vascular prostheses (10 cm length, 6 mm (phi) ) were perforated with an excimer laser ((phi) of the holes 50 - 100 micrometer, distance 4 mm) and implanted into the carotid arteries of 8 sheep. The laser tissue interaction process of 193 nm radiation ensures minimal thermal damage to the prostheses. They were compared to untreated OmniflowTM prostheses implanted at the contralateral side. Three months after implantation the prostheses were explanted and evaluated by gross morphology, histological examination and scanning electron microscopy. Scanning electron microscopy showed endothelial cells in the midgraft portion of all perforated prostheses, whereas collagen fibers, fibrin meshwork and activated platelets formed the inner layer in 6 out of 8 untreated OmniflowTM prostheses. It can be concluded, that spontaneous endothelialization of biosynthetic vascular prostheses can be achieved by transmural capillary ingrowth through perforations in the wall of the prostheses in an experimental sheep model.

  12. Advanced excimer laser technologies enable green semiconductor manufacturing

    Science.gov (United States)

    Fukuda, Hitomi; Yoo, Youngsun; Minegishi, Yuji; Hisanaga, Naoto; Enami, Tatsuo

    2014-03-01

    "Green" has fast become an important and pervasive topic throughout many industries worldwide. Many companies, especially in the manufacturing industries, have taken steps to integrate green initiatives into their high-level corporate strategies. Governments have also been active in implementing various initiatives designed to increase corporate responsibility and accountability towards environmental issues. In the semiconductor manufacturing industry, there are growing concerns over future environmental impact as enormous fabs expand and new generation of equipments become larger and more powerful. To address these concerns, Gigaphoton has implemented various green initiatives for many years under the EcoPhoton™ program. The objective of this program is to drive innovations in technology and services that enable manufacturers to significantly reduce both the financial and environmental "green cost" of laser operations in high-volume manufacturing environment (HVM) - primarily focusing on electricity, gas and heat management costs. One example of such innovation is Gigaphoton's Injection-Lock system, which reduces electricity and gas utilization costs of the laser by up to 50%. Furthermore, to support the industry's transition from 300mm to the next generation 450mm wafers, technologies are being developed to create lasers that offer double the output power from 60W to 120W, but reducing electricity and gas consumption by another 50%. This means that the efficiency of lasers can be improve by up to 4 times in 450mm wafer production environments. Other future innovations include the introduction of totally Heliumfree Excimer lasers that utilize Nitrogen gas as its replacement for optical module purging. This paper discusses these and other innovations by Gigaphoton to enable green manufacturing.

  13. XeCl Excimer Laser For Micro - Machining Of Materials: Preliminary Theoretical And Experimental Works.

    Science.gov (United States)

    Iwanejko, Leszek; Pokora, Ludwik; Stefanski, Miroslaw; Ujda, Zbigniew

    1987-10-01

    The paper presents the results of preliminary investigations, both theoretical and experimental, of XeC1 excimer laser pumped by transverse electric discharge with UU preionization. The medium was a mixture of gases He-Xe-HC1. A theoretical model of the XeC1 laser was worked out and a lot of laser parameters calculations were done. In the same time an excimer laser operating on the mixture He-Xe-HC1 was started, the generation of laser radiation was of energy about 20mJ.

  14. 308-nm excimer laser ablation of human cartilage

    Science.gov (United States)

    Prodoehl, John A.; Rhodes, Anthony L.; Meller, Menachem M.; Sherk, Henry H.

    1993-07-01

    The XeCl excimer laser was investigated as an ablating tool for human fibrocartilage and hyaline cartilage. Quantitative measurements were made of tissue ablation rates as a function of fluence in meniscal fibrocartilage and articular hyaline cartilage. A force of 1.47 Newtons was applied to an 800 micrometers fiber with the laser delivering a range of fluences (40 to 190 mj/mm2) firing at a frequency of 5 Hz. To assess the effect of repetition rate on ablation rate, a set of measurements was made at a constant fluence of 60 mj/mm2, with the repetition rate varying from 10 to 40 Hz. Histologic and morphometric analysis was performed using light microscopy. The results of these studies revealed that the ablation rate was directly proportional to fluence over the range tested. Fibrocartilage was ablated at a rate 2.56 times faster than hyaline cartilage at the maximum fluence tested. Repetition rate had no effect on the penetration per pulse. Adjacent tissue damage was noted to be minimal (10 - 70 micrometers ).

  15. Microencapsulation of silicon cavities using a pulsed excimer laser

    KAUST Repository

    Sedky, Sherif M.

    2012-06-07

    This work presents a novel low thermal-budget technique for sealing micromachined cavities in silicon. Cavities are sealed without deposition, similar to the silicon surface-migration sealing process. In contrast to the 1100°C furnace anneal required for the migration process, the proposed technique uses short excimer laser pulses (24ns), focused onto an area of 23mm 2, to locally heat the top few microns of the substrate, while the bulk substrate remains near ambient temperature. The treatment can be applied to selected regions of the substrate, without the need for special surface treatments or a controlled environment. This work investigates the effect of varying the laser pulse energy from 400 mJ cm 2to 800 mJ cm 2, the pulse rate from 1Hz to 50Hz and the pulse count from 200 to 3000 pulses on sealing microfabricated cavities in silicon. An analytical model for the effect of holes on the surface temperature distribution is derived, which shows that much higher temperatures can be achieved by increasing the hole density. A mechanism for sealing the cavities is proposed, which indicates how complete sealing is feasible. © 2012 IOP Publishing Ltd.

  16. Investigation on gas medium parameters for an ArF excimer laser through orthogonal experimental design

    Science.gov (United States)

    Song, Xingliang; Sha, Pengfei; Fan, Yuanyuan; Jiang, R.; Zhao, Jiangshan; Zhou, Yi; Yang, Junhong; Xiong, Guangliang; Wang, Yu

    2018-02-01

    Due to complex kinetics of formation and loss mechanisms, such as ion-ion recombination reaction, neutral species harpoon reaction, excited state quenching and photon absorption, as well as their interactions, the performance behavior of different laser gas medium parameters for excimer laser varies greatly. Therefore, the effects of gas composition and total gas pressure on excimer laser performance attract continual research studies. In this work, orthogonal experimental design (OED) is used to investigate quantitative and qualitative correlations between output laser energy characteristics and gas medium parameters for an ArF excimer laser with plano-plano optical resonator operation. Optimized output laser energy with good pulse to pulse stability can be obtained effectively by proper selection of the gas medium parameters, which makes the most of the ArF excimer laser device. Simple and efficient method for gas medium optimization is proposed and demonstrated experimentally, which provides a global and systematic solution. By detailed statistical analysis, the significance sequence of relevant parameter factors and the optimized composition for gas medium parameters are obtained. Compared with conventional route of varying single gas parameter factor sequentially, this paper presents a more comprehensive way of considering multivariables simultaneously, which seems promising in striking an appropriate balance among various complicated parameters for power scaling study of an excimer laser.

  17. Time Evolution of the Excimer State of a Conjugated Polymer Laser

    Directory of Open Access Journals (Sweden)

    Wafa Musa Mujamammi

    2017-11-01

    Full Text Available An excited dimer is an important complex formed in nano- or pico-second time scales in many photophysics and photochemistry applications. The spectral and temporal profile of the excimer state of a laser from a new conjugated polymer, namely, poly (9,9-dioctylfluorenyl-2,7-diyl (PFO, under several concentrations in benzene were investigated. These solutions were optically pumped by intense pulsed third-harmonic Nd:YAG laser (355-nm to obtain the amplified spontaneous emission (ASE spectra of a monomer and an excimer with bandwidths of 6 and 7 nm, respectively. The monomer and excimer ASEs were dependent on the PFO concentration, pump power, and temperature. Employing a sophisticated picosecond spectrometer, the time evolution of the excimer state of this polymer, which is over 400 ps, can be monitored.

  18. Unscheduled DNA synthesis in human skin after in vitro ultraviolet-excimer laser ablation

    International Nuclear Information System (INIS)

    Green, H.A.; Margolis, R.; Boll, J.; Kochevar, I.E.; Parrish, J.A.; Oseroff, A.R.

    1987-01-01

    DNA damage repaired by the excision repair system and measured as unscheduled DNA synthesis (UDS) was assessed in freshly excised human skin after 193 and 248 nm ultraviolet (UV)-excimer laser ablative incisions. Laser irradiation at 248 nm induced DNA damage throughout a zone of cells surrounding the ablated and heat-damaged area. In contrast, with 193 nm irradiation UDS was not detected in cells adjacent to the ablated area, even though DNA strongly absorbs this wavelength. Our results suggest that the lack of UDS after 193 nm irradiation is due to: ''shielding'' of DNA by the cellular interstitium, membrane, and cytoplasm, DNA damage that is not repaired by excision repair, or thermal effects that either temporarily or permanently inhibit the excision repair processes

  19. Unscheduled DNA synthesis in human skin after in vitro ultraviolet-excimer laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Green, H.A.; Margolis, R.; Boll, J.; Kochevar, I.E.; Parrish, J.A.; Oseroff, A.R.

    1987-08-01

    DNA damage repaired by the excision repair system and measured as unscheduled DNA synthesis (UDS) was assessed in freshly excised human skin after 193 and 248 nm ultraviolet (UV)-excimer laser ablative incisions. Laser irradiation at 248 nm induced DNA damage throughout a zone of cells surrounding the ablated and heat-damaged area. In contrast, with 193 nm irradiation UDS was not detected in cells adjacent to the ablated area, even though DNA strongly absorbs this wavelength. Our results suggest that the lack of UDS after 193 nm irradiation is due to: ''shielding'' of DNA by the cellular interstitium, membrane, and cytoplasm, DNA damage that is not repaired by excision repair, or thermal effects that either temporarily or permanently inhibit the excision repair processes.

  20. Treatment of alopecia areata with the 308-nm xenon chloride excimer laser: case report of two successful treatments with the excimer laser.

    Science.gov (United States)

    Gundogan, Cuneyt; Greve, Bärbel; Raulin, Christian

    2004-01-01

    Alopecia areata is a common disease of unknown etiology; it causes significant cosmetic and psycho-social distress for most of the people it affects. We report on an innovative form of treatment in two patients with typical alopecia areata on the capillitium. We successfully treated two patients whose alopecia areata had worsened progressively for 3 and 14 weeks. The treatment involved the use of a 308 nm xenon chloride excimer laser (dosage 300-2,300 mJ/cm(2) per session). After 11 and 12 sessions within a 9-week and 11-week period, the entire affected focus showed homogenous and thick regrowth. No relapse was observed during the follow-up period of 5 and 18 months. The use of the excimer laser is an effective, elegant, and safe means of treatment and has good tolerability. Analogous to topical treatment of alopecia areata, the immunosuppressive mechanism of the excimer laser can be interpreted as an induction of T-cell apoptosis. This new means of treatment has yet to be discussed in medical literature. Further studies with greater numbers are needed to assess its potential more precisely and evaluate the excimer laser in treating alopecia areata. Copyright 2004 Wiley-Liss, Inc.

  1. Excimer laser for the treatment of psoriasis: safety, efficacy, and patient acceptability

    Directory of Open Access Journals (Sweden)

    Abrouk M

    2016-12-01

    Full Text Available Michael Abrouk,1 Ethan Levin,2 Merrick Brodsky,1 Jessica R Gandy,1 Mio Nakamura,2 Tian Hao Zhu,3 Benjamin Farahnik,4 John Koo,2 Tina Bhutani2 1Irvine School of Medicine, Irvine, 2Department of Dermatology, Psoriasis and Skin Treatment Center, University of California, San Francisco, 3Department of Dermatology, University of Southern California Keck School of Medicine, Los Angeles, CA, 4Department of Dermatology, University of Vermont College of Medicine, Burlington, VT, USA Introduction: The 308 nm excimer laser is a widely used device throughout the field of dermatology for many diseases including psoriasis. Although the laser has demonstrated clinical efficacy, there is a lack of literature outlining the safety, efficacy, and patient acceptability of the excimer laser. Methods: A literature search on PubMed was used with combinations of the terms “excimer”, “excimer laser”, “308 nm”, “psoriasis”, “protocol”, “safety”, “efficacy”, acceptability”, “side effects”, and “dose”. The search results were included if they contained information pertaining to excimer laser and psoriasis treatment and description of the safety, efficacy, and patient acceptability of the treatment. Results: The 308 nm excimer laser is generally safe and well tolerated with minimal side effects including erythema, blistering, and pigmentary changes. It has a range of efficacies depending on the protocol used with several different treatment protocols, including the induration protocol, the minimal erythema dose protocol, and the newer minimal blistering dose protocol. Conclusion: Although the excimer laser is not a first-line treatment, it remains an excellent treatment option for psoriasis patients and has been demonstrated to be an effective treatment with little to no side effects. Keywords: excimer, laser, 308 nm, psoriasis, safety, efficacy

  2. A comparison of the characteristics of excimer and femtosecond laser ablation of acrylonitrile butadiene styrene (ABS)

    International Nuclear Information System (INIS)

    See, Tian Long; Liu, Zhu; Li, Lin; Zhong, Xiang Li

    2016-01-01

    Highlights: • Ablation threshold for excimer laser is lower compared to femtosecond laser. • Effective optical penetration depth for excimer laser is lower compared to femtosecond laser. • Two ablation characteristic regimes are observed for femtosecond laser ablation. • Reduction of C=C bond following excimer or fs laser ablation is observed. • Addition of oxygen- and nitrogen-rich functional groups is observed. - Abstract: This paper presents an investigation on the ablation characteristics of excimer laser (λ = 248 nm, τ = 15 ns) and femtosecond laser (λ = 800 nm, τ = 100 fs) on ABS polymer sheets. The laser–material interaction parameters (ablation threshold, optical penetration depth and incubation factor) and the changes in material chemical properties were evaluated and compared between the two lasers. The work shows that the ablation threshold and effective optical penetration depth values are dependent on the wavelength of laser beam (photon energy) and the pulse width. The ablation threshold value is lower for the excimer laser ablation of ABS (F_t_h = 0.087 J/cm"2) than that for the femtosecond laser ablation of ABS (F_t_h = 1.576 J/cm"2), demonstrating a more dominating role of laser wavelength than the pulse width in influencing the ablation threshold. The ablation depth versus the logarithmic scale of laser fluence shows two linear regions for the fs laser ablation, not previously known for polymers. The effective optical penetration depth value is lower for excimer laser ablation (α"−"1 = 223 nm) than that for femtosecond laser ablation (α"−"1 = 2917 nm). The ablation threshold decreases with increasing number of pulses (NOP) due to the chain scission process that shortens the polymeric chains, resulting in a weaker polymeric configuration and the dependency is governed by the incubation factor. Excimer laser treatment of ABS eliminates the C=C bond completely through the chain scission process whereas C=C bond is partially

  3. A comparison of the characteristics of excimer and femtosecond laser ablation of acrylonitrile butadiene styrene (ABS)

    Energy Technology Data Exchange (ETDEWEB)

    See, Tian Long, E-mail: tianlong.see@postgrad.manchester.ac.uk [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom); Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, M13 9PL Manchester (United Kingdom); Liu, Zhu [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom); Li, Lin [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, M13 9PL Manchester (United Kingdom); Zhong, Xiang Li [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom)

    2016-02-28

    Highlights: • Ablation threshold for excimer laser is lower compared to femtosecond laser. • Effective optical penetration depth for excimer laser is lower compared to femtosecond laser. • Two ablation characteristic regimes are observed for femtosecond laser ablation. • Reduction of C=C bond following excimer or fs laser ablation is observed. • Addition of oxygen- and nitrogen-rich functional groups is observed. - Abstract: This paper presents an investigation on the ablation characteristics of excimer laser (λ = 248 nm, τ = 15 ns) and femtosecond laser (λ = 800 nm, τ = 100 fs) on ABS polymer sheets. The laser–material interaction parameters (ablation threshold, optical penetration depth and incubation factor) and the changes in material chemical properties were evaluated and compared between the two lasers. The work shows that the ablation threshold and effective optical penetration depth values are dependent on the wavelength of laser beam (photon energy) and the pulse width. The ablation threshold value is lower for the excimer laser ablation of ABS (F{sub th} = 0.087 J/cm{sup 2}) than that for the femtosecond laser ablation of ABS (F{sub th} = 1.576 J/cm{sup 2}), demonstrating a more dominating role of laser wavelength than the pulse width in influencing the ablation threshold. The ablation depth versus the logarithmic scale of laser fluence shows two linear regions for the fs laser ablation, not previously known for polymers. The effective optical penetration depth value is lower for excimer laser ablation (α{sup −1} = 223 nm) than that for femtosecond laser ablation (α{sup −1} = 2917 nm). The ablation threshold decreases with increasing number of pulses (NOP) due to the chain scission process that shortens the polymeric chains, resulting in a weaker polymeric configuration and the dependency is governed by the incubation factor. Excimer laser treatment of ABS eliminates the C=C bond completely through the chain scission process whereas

  4. Boron-enhanced diffusion in excimer laser annealed Si

    International Nuclear Information System (INIS)

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Privitera, V.; Fortunato, G.; Mariucci, L.

    2004-01-01

    The effect of excimer laser annealing (ELA) and rapid thermal annealing (RTA) on B redistribution in B-implanted Si has been studied by secondary ion mass spectrometry (SIMS) and spreading resistance probe (SRP). B has been implanted with an energy of 1 keV and a dose of 10 16 cm -2 forming a distribution with a width of 20-30 nm and a peak concentration of ∼5 x 10 21 cm -3 . It has been found that ELA with 10 pulses of the energy density of 850 mJ/cm 2 results in a uniform B distribution over the ELA-molten region with an abrupt profile edge. SRP measurements demonstrate good activation of the implanted B after ELA, with the concentration of the activated fraction (∼10 21 cm -3 ) exceeding the solid solubility level. RTA (30 s at 1100 deg. C) of the as-implanted and ELA-treated samples leads to a diffusion of B with diffusivities exceeding the equilibrium one and the enhancement is similar for both of the samples. It is also found that RTA decreases the activated B in the ELA-treated sample to the solid solubility limit (2 x 10 20 cm -3 ). The similarity of the B diffusivity for the as-implanted and ELA-treated samples suggests that the enhancement of the B diffusivity is due to the so-called boron-enhanced diffusion (BED). Possible mechanisms of BED are discussed

  5. High efficiency metal marking with CO2 laser and glass marking with excimer laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    with a thoroughly tested ray-tracing model is presented and compared with experimental results. Special emphasis is put on two different applications namely marking in metal with TEA-CO2 laser and marking in glass with excimer laser. The results are evaluated on the basis of the achievable energy enhancement......Today, mask based laser materials processing and especially marking is widely used. However, the energy efficiency in such processes is very low [1].This paper gives a review of the results, that may be obtained using the energy enhancing technique [1]. Results of simulations performed...

  6. KrF excimer laser precision machining of hard and brittle ceramic biomaterials

    International Nuclear Information System (INIS)

    Huang, Yao-Xiong; Lu, Jian-Yi; Huang, Jin-Xia

    2014-01-01

    KrF excimer laser precision machining of porous hard–brittle ceramic biomaterials was studied to find a suitable way of machining the materials into various desired shapes and sizes without distorting their intrinsic structure and porosity. Calcium phosphate glass ceramics (CPGs) and hydroxyapatite (HA) were chosen for the study. It was found that KrF excimer laser can cut both CPGs and HA with high efficiency and precision. The ablation rates of CPGs and HA are respectively 0.081 µm/(pulse ⋅ J cm −2 ) and 0.048 µm/(pulse ⋅ J cm −2 ), while their threshold fluences are individually 0.72 and 1.5 J cm −2 . The cutting quality (smoothness of the cut surface) is a function of laser repetition rate and cutting speed. The higher the repetition rate and lower the cutting speed, the better the cutting quality. A comparison between the cross sections of CPGs and HA cut using the excimer laser and using a conventional diamond cutting blade indicates that those cut by the excimer laser could retain their intrinsic porosity and geometry without distortion. In contrast, those cut by conventional machining had distorted geometry and most of their surface porosities were lost. Therefore, when cutting hard–brittle ceramic biomaterials to prepare scaffold and implant or when sectioning them for porosity evaluation, it is better to choose KrF excimer laser machining. (paper)

  7. Laser-driven hydrothermal process studied with excimer laser pulses

    Science.gov (United States)

    Mariella, Raymond; Rubenchik, Alexander; Fong, Erika; Norton, Mary; Hollingsworth, William; Clarkson, James; Johnsen, Howard; Osborn, David L.

    2017-08-01

    Previously, we discovered [Mariella et al., J. Appl. Phys. 114, 014904 (2013)] that modest-fluence/modest-intensity 351-nm laser pulses, with insufficient fluence/intensity to ablate rock, mineral, or concrete samples via surface vaporization, still removed the surface material from water-submerged target samples with confinement of the removed material, and then dispersed at least some of the removed material into the water as a long-lived suspension of nanoparticles. We called this new process, which appears to include the generation of larger colorless particles, "laser-driven hydrothermal processing" (LDHP) [Mariella et al., J. Appl. Phys. 114, 014904 (2013)]. We, now, report that we have studied this process using 248-nm and 193-nm laser light on submerged concrete, quartzite, and obsidian, and, even though light at these wavelengths is more strongly absorbed than at 351 nm, we found that the overall efficiency of LDHP, in terms of the mass of the target removed per Joule of laser-pulse energy, is lower with 248-nm and 193-nm laser pulses than with 351-nm laser pulses. Given that stronger absorption creates higher peak surface temperatures for comparable laser fluence and intensity, it was surprising to observe reduced efficiencies for material removal. We also measured the nascent particle-size distributions that LDHP creates in the submerging water and found that they do not display the long tail towards larger particle sizes that we had observed when there had been a multi-week delay between experiments and the date of measuring the size distributions. This is consistent with transient dissolution of the solid surface, followed by diffusion-limited kinetics of nucleation and growth of particles from the resulting thin layer of supersaturated solution at the sample surface.

  8. The effect of excimer laser keratectomy on corneal glutathione-related enzymes in rabbits.

    Science.gov (United States)

    Bilgihan, Ayşe; Bilgihan, Kamil; Yis, Ozgür; Yis, Nilgün Safak; Hasanreisoglu, Berati

    2003-04-01

    Glutathione related enzymes are involved in the metabolism and detoxification of cytotoxic and carcinogenic compounds as well as reactive oxygen species. Excimer laser is a very useful tool for the treatment of refractive errors and removing superficial corneal opacities. Previous studies have shown that excimer laser may initiate free radical formation in the cornea. In the present study, we evaluated the effect of excimer laser keratectomy on corneal glutathione-related enzyme activities in rabbits. Animals were divided into five groups, and all groups were compared with the controls (group 1), after epithelial scraping (group 2), transepithelial photorefractive keratectomy (PRK) (group 3), traditional PRK (group 4) and deep traditional PRK (group 5). Corneal glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) activities were measured after 24h. Corneal GPx and GR activities significantly decreased only in group 5 (p < 0.05) but GST activities significantly decreased in all groups when compared with the control group (p < 0.05). In conclusion, excimer laser inhibits the glutathione dependent defense system in the cornea, this effect becomes more prominent after high doses of excimer laser energy and antioxidants may be useful to reduce free radical mediated complications.

  9. XeCl Excimer Laser with Three- and Four-Component Mixture of Active Gases

    International Nuclear Information System (INIS)

    Iwanejko, L.; Pokora, L.

    1998-01-01

    Selected results of investigations of a XeCl excimer laser employing a new type (four-component)of mixture of gases, He-Kr:Xe-HCl, are presented. The mixture includes, instead of Xe, a mixture of not-separated Kr and Xe gases, much less expensive than pure xenon. A comparison of durations and energies of pulses generated in the XeCl excimer laser using three- or four-component gaseous active medium (He-Xe-HCl or He-Kr:Xe-HCl) is made. The investigations have been carried out with the use of a laser system with UV preionization and self sustained pumping discharge. (author)

  10. Stability of a 1-kW excimer laser with long optical pulses

    NARCIS (Netherlands)

    Timmermans, J.C.M.; Hofmann, T.; Hofmann, Th.; van Goor, F.A.; Witteman, W.J.

    1996-01-01

    For high repetition operation of excimer-lasers care has to be taken of the changing performance of the electrical circuit, gas dynamic effects and contamination of the gas mixture to avoid deterioration of the laser performance. The parameters that influence the stability of the discharge are

  11. Surface modification of polyethylene terephthalate using excimer and CO2 laser

    International Nuclear Information System (INIS)

    Mirzadeh, H.; Dadsetan, M.

    2002-01-01

    Complete text of publication follows. Attempts have been made to evaluate microstructuring which affects cell behaviour, physical and chemical changes produced by laser irradiation onto the polyethylene terephthalate (PET) surface. The surfaces of PET were irradiated using the CO 2 laser and KrF excimer pulsed laser. The changes in chemical and physical properties of the irradiated PET surface were investigated by attenuated total reflectance infrared spectroscopy (ATR-IR) and contact angle measurements. ATR-IR Spectra showed that the crystallinity in the surface region decreased due to the CO 2 laser and excimer laser irradiation. Scanning electron microscopy observations showed that the morphology of the laser irradiated PET surface changed due to laser irradiation. The results obtained from the cell behaviour studies revealed that changes of physico-chemical properties of the laser treated PET film have significantly changed in comparison with the unmodified PET

  12. Physical and optical limitations using ArF-excimer and Er:YAG lasers for PRK

    Science.gov (United States)

    Semchishen, Vladimir A.; Mrochen, Michael; Seiler, Theo

    1998-06-01

    The Erbium:YAG laser emitting at a wavelength of 2,94 micrometer have been promised as an alternative laser for the ArF-excimer laser (193 nm) in photorefractive keratectomy (PRK). This report discusses the limitations of laser parameters such as wavelength, energy density and pulse duration for the ablation of the cornea. In addition, the melting process during ablation on the corneal surface roughness may play a role.

  13. Hydrophilicity and morphological investigation of polycarbonate irradiated by ArF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Jaleh, B. [Bu-Ali-Sina University, Physics Department, Postal Code 65174, Hamedan (Iran, Islamic Republic of)], E-mail: jaleh@basu.ac.ir; Parvin, P. [Amir Kabir University of Technology, Physics Department, P.O. Box: 15875-4413, Tehran (Iran, Islamic Republic of); Laser Research Center, AEOI, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of); Sheikh, N. [Nuclear Science and Technology Research Institute, Radiation Applications Research School, Tehran (Iran, Islamic Republic of); Zamanipour, Z. [Laser Research Center, AEOI, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of); Sajad, B. [Azzahra University, Physics Department, Tehran (Iran, Islamic Republic of)

    2007-12-15

    Lasers are used to modify polymeric materials. In this work, a number of polycarbonate (PC) pieces were exposed by ArF excimer laser, 193 nm, at various UV doses from 10 to 100 J/cm{sup 2} with 50-500 mJ/pulse at 10 Hz pulse repetition rate. Morphology of PC has been investigated by scanning electron microscope (SEM) at three regimes pre-ablation, slow and fast ablation. SEM identifies that the conical defects are created on the polymer surface to grow opposite to the direction of laser irradiation. It increases the superficial absorptivity of the material dependent on the ArF laser induced conical microstructure geometry. The contact angle measurement was performed here, in order to determine the hydrophilicity of the irradiated polymer at various coherent doses. It is shown that the contact angle of PC samples which are exposed to the ArF laser significantly alters with UV dose below 7 J/cm{sup 2}.

  14. DNA damage in cultured human skin fibroblasts exposed to excimer laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rimoldi, D.; Miller, A.C.; Freeman, S.E.; Samid, D. (Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD (USA))

    1991-06-01

    Ultraviolet excimer lasers are being considered for use in a variety of refractive and therapeutic procedures, the long-term biologic consequences of which are unknown. The effect of sublethal doses of 193-nm laser radiation on cellular DNA was examined in cultured human skin fibroblasts. In contrast to 248 nm, treatments with the 193-nm laser radiation below 70 J/m2 did not cause significant pyrimidine dimer formation in the skin cells. This was indicated by the lack of excision repair activities (unscheduled DNA synthesis assay), and further demonstrated by direct analysis of pyrimidine dimers in DNA from irradiated cells. However, a low level of unscheduled DNA synthesis could be detected following irradiation at 193 nm with 70 J/m2. Both the 193-nm and 248-nm radiation were able to induce chromosomal aberrations, as indicated by a micronucleus assay. A dose-dependent increase in micronuclei frequency was observed 48 and 72 h after laser irradiation. These results indicate that exposure of actively replicating human skin fibroblasts to sublethal doses of either 193- or 248-nm laser radiation can result in genotoxicity.

  15. The effect of excimer laser pretreatment on diffusion and activation of boron implanted in silicon

    International Nuclear Information System (INIS)

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Italia, M.; Privitera, V.; Fortunato, G.; Cuscuna, M.; Mariucci, L.

    2005-01-01

    We have investigated the effect of excimer laser annealing (ELA) on transient enhanced diffusion (TED) and activation of boron implanted in Si during subsequent rapid thermal annealing (RTA). It is observed that ELA with partial melting of the implanted region causes reduction of TED in the region that remains solid during ELA, where the diffusion length of boron is reduced by a factor of ∼4 as compared to the as-implanted sample. This is attributed to several mechanisms such as liquid-state annealing of a fraction of the implantation induced defects, introduction of excess vacancies during ELA, and solid-state annealing of the defects beyond the maximum melting depth by the heat wave propagating into the Si wafer. The ELA pretreatment provides a substantially improved electrical activation of boron during subsequent RTA

  16. ArF excimer laser modulation of TNF-alpha and gelatinase B in NIH 3T3 cells

    International Nuclear Information System (INIS)

    Naudy-Vives, C.; Courant, D.; Perot, J.C.; Garcia, J.; Fretier, P.; Court, L.; Dormont, D.

    1995-01-01

    The effects on TNF-alpha and gelatinase B activity in mammalian cells induced by 193 nm argon fluoride excimer laser have been investigated. The data show that a secretion of 92 kDa type IV collagenase and TNF-alpha were increased in cell culture supernatants. Moreover, the 193 nm laser radiation produces a decrease of cell proliferation and an increase of cell activation 8 hours after irradiation. The total protein amount increases with the delivered dose. Same, but less effects were obtained after exposure to a conventional UV lamp at 254 nm. (author)

  17. [The 308 nm Excimer laser for the treatment of psoriasis and inflammatory skin diseases].

    Science.gov (United States)

    Fritz, K; Salavastru, C

    2018-01-01

    Overall, the 308 nm Excimer laser enables not only a more effective and safer UVB therapy than classical UV phototherapy, but also targeted irradiation in higher doses with a lower cumulative load, which results in faster healing of mainly circumscribed skin changes. This also applies to therapy-resistant residual lesions which, despite systemic therapy, did not diminish. Combination therapies usually improve the result and enable the dose of UVB and systemic medication to be reduced. Excimer laser therapy can be used for an increasing number of skin diseases, especially those that respond to phototherapy or photochemotherapy.

  18. Levels of interleukin-6 in tears before and after excimer laser treatment

    Directory of Open Access Journals (Sweden)

    Resan Mirko

    2015-01-01

    Full Text Available Background/Aim. Immune response and consequent inflammatory process which originate on ocular surface after a trauma are mediated by cytokines. Photoablation of corneal stroma performed by excimer laser causes surgically induced trauma. Interleukin-6 (IL-6 is mostly known as a proinflammatory cytokine. However, it also has regenerative and anti-inflammatory effects. It is supposed that this cytokine is likely to play a significant role in the process of corneal wound healing response after photoablation of stroma carried out by laser in situ keratomileusis (LASIK or photorefractive keratectomy (PRK methods. The aim of this study was to determine and compare the levels of IL-6 in tears before and after treatment with LASIK and PRK methods. Methods. The study included 68 shortsighted eyes up to -3.0 diopter sphere, i.e. 198 samples of tears (per three samples taken from each of the eyes, divided into two groups according to the kind of excimer laser intervention performed: the group 1 - eyes treated by LASIK method (n = 31, and the group 2 - eyes treated by the PRK method (n = 37. The samples of tears were taken from each eye at the following time points: before excimer laser treatment (0 h, the control group, 1 h after the treatment (1 h and 24 h after the treatment (24 h. The patients did not use anti-inflammatory therapy 24 h after the intervention. Tear samples were collected using microsurgical sponge. Level of IL-6 in tear fluid was determined by the flow cytometry method, applying a commercial test kit which allowed cytokine detection from a small sample volume. Results. The values of IL-6 were detectable in 16% of samples before LASIK treatment and in 30% of samples before PRK treatment. One h after the treatment IL-6 was detectable in 29% of samples for the LASIK group and 43% of samples for the PRK group, and 24 h after the treatment it was detectable in 19% of samples for the LASIK group and in 57% of samples for the PRK group. When we

  19. Levels of interleukin-6 in tears before and after excimer laser treatment.

    Science.gov (United States)

    Resan, Mirko; Stanojević, Ivan; Petković, Aleksandra; Pajić, Bojan; Vojvodić, Danilo

    2015-04-01

    Immune response and consequent inflammatory process which originate on ocular surface after a trauma are mediated by cytokines. Photoablation of corneal stroma performed by excimer laser causes surgically induced trauma. Interleukin-6 (IL-6) is mostly known as a proinflammatory cytokine. However, it also has regenerative and anti-inflammatory effects. It is supposed that this cytokine is likely to play a significant role in the process of corneal wound healing response after photoablation of stroma carried out by laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) methods. The aim of this study was to determine and compare the levels of IL-6 in tears before and after treatment with LASIK and PRK methods. The study included 68 shortsighted eyes up to -3.0 diopter sphere, i.e. 198 samples of tears (per three samples taken from each of the eyes), divided into two groups according to the kind of excimer laser intervention performed: the group 1--eyes treated by LASIK method (n=31), and the group 2--eyes treated by the PRK method (n=37). The samples of tears were taken from each eye at the following time points: before excimer laser treatment (0 h, the control group), 1 h after the treatment (1 h) and 24 h after the treatment (24 h). The patients did not use anti-inflammatory therapy 24 h after the intervention. Tear samples were collected using microsurgical sponge. Level of IL-6 in tear fluid was determined by the flow cytometry method, applying a commercial test kit which allowed cytokine detection from a small sample volume. Results. The values of IL-6 were detectable in 16% of samples before LASIK treatment and in 30% of samples before PRK treatment. One h after the treatment IL-6 was detectable in 29% of samples for the LASIK group and 43% of samples for the PRK group, and 24 h after the treatment it was detectable in 19% of samples for the LASIK group and in 57% of samples for the PRK group. When we analyzed the dynamics of IL76 production

  20. Aqueous transforming growth factor-beta-I levels in rabbit eyes after excimer laser photoablation.

    Science.gov (United States)

    Bilgihan, K; Gürelik, G; Okur, H; Bilgihan, A; Hasanreisoglu, B; Imir, T

    1997-01-01

    Transforming growth factor beta (TGF-beta) plays an important role in anterior segment wound healing, by controlling the cell proliferation and differentiation, angiogenesis, extracellular matrix composition and mediating the immunosuppressive properties of the aqueous humor. The present study was undertaken to clarify the possible changes of aqueous humor TGF-betaI levels after excimer laser photoablation. Twenty-eight New Zealand rabbits were divided into four groups of 7 rabbits each. Group 1 served as control, the central 7 mm of corneal epithelium was removed in groups 2, 3 and 4. We performed 50-microm corneal photoablation in group 3, and 100-microm ablation in group 4. After 48 h we measured the TGF-betaI levels of the aqueous humor by ELISA method. The mean TGF-betaI value of the aqueous humor was found to be 162.94+/-13.73 pg/ml in the control group. Mechanical deepithelialization did not change the TGF-betaI levels of the aqueous humor (p > 0.05). There was no significant difference between the 50-microm photoablated group and the controls (p > 0.05), but the TGF-betaI levels of the 100-microm photoablated group were found to be significantly higher than those of both the control group and 50-microm photoablated group (p < 0.05). Many factors and cytokines may induce corneal haze and myopic regression after excimer laser photoablation; our study demonstrated that TGF-betaI is one of these factors and there is a positive correlation between the depth of corneal photoablation and aqueous TGF-betaI concentrations.

  1. Investigation of excimer laser ablation threshold of polymers using a microphone

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, Joerg; Niino, Hiroyuki; Yabe, Akira

    2002-09-30

    KrF excimer laser ablation of polyethylene terephthalate (PET), polyimide (PI) and polycarbonate (PC) in air was studied by an in situ monitoring technique using a microphone. The microphone signal generated by a short acoustic pulse represented the etch rate of laser ablation depending on the laser fluence, i.e., the ablation 'strength'. From a linear relationship between the microphone output voltage and the laser fluence, the single-pulse ablation thresholds were found to be 30 mJ cm{sup -2} for PET, 37 mJ cm{sup -2} for PI and 51 mJ cm{sup -2} for PC (20-pulses threshold). The ablation thresholds of PET and PI were not influenced by the number of pulses per spot, while PC showed an incubation phenomenon. A microphone technique provides a simple method to determine the excimer laser ablation threshold of polymer films.

  2. Excimer laser coronary atherectomy in septal collaterals during retrograde recanalization of a chronic total occlusion

    Directory of Open Access Journals (Sweden)

    Bernward Lauer

    2011-09-01

    Full Text Available Management of chronic total occlusions has been refined through the development of a retrograde approach via collateral pathways. We describe the use of Excimer Laser Coronary Atherectomy in the septal collaterals. This appraoch was not yet described in the literature.

  3. A pulsed electron injector using a metal photocathode irradiated by an excimer laser

    International Nuclear Information System (INIS)

    Kauppila, T.J.; Builta, L.A.; Crutcher, J.K.; Elliott, J.C.; Moir, D.C.

    1987-01-01

    The hot cathode of an electron gun is replaced by a metallic photocathode driven by an excimer laser. The current, current density, and emittance of the 500-kV electron beam produced by the photoelectron source are presented. In addition, the temperature of the photocathode is varied to study the possibility of a hybrid source

  4. Refractive microlenses produced by excimer laser machining of poly(methyl methacrylate)

    DEFF Research Database (Denmark)

    Jensen, Martin Frøhling; Krühne, Ulrich; H., L.

    2005-01-01

    A method has been developed whereby refractive microlenses can be produced in poly (methyl methacrylate) by excimer laser irradiation at λ = 248 nm. The lenses are formed by a combined photochemical and thermal process. The lenses are formed as depressions in the substrate material (negative foca...

  5. Excimer laser crystallization of InGaZnO4 on SiO2 substrate

    NARCIS (Netherlands)

    Chen, T.; Wu, M.Y.; Ishihara, R.; Nomura, K.; Kamiya, T.; Hosono, H.; Beenakker, C.I.M.

    2011-01-01

    In this paper, we were able to crystallize InGaZnO4 (IGZO) by excimer laser on SiO2 substrate. It was observed that uniform [0001] textured polycrystalline IGZO film has been obtained without any grain boundaries and oxygen vacancies on SiO2 substrate. This process is very promising in fabricating

  6. Performance characteristics of an excimer laser (XeCl) with single ...

    Indian Academy of Sciences (India)

    2017-01-10

    Jan 10, 2017 ... Performance characteristics of an excimer laser (XeCl) with single-stage magnetic ... the stress can increase the lifetime of the switches and ..... work. References. [1] Ying-Tung Chen, Kris Naessens, Roel Bates, Yunn-Shiuan.

  7. Excimer laser texturing of natural composite polymer surfaces for studying cell-to-substrate specific response

    Energy Technology Data Exchange (ETDEWEB)

    Dinca, V., E-mail: dincavalentina@yahoo.com [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Alloncle, P.; Delaporte, P. [Aix-Marseille University, CNRS, LP3 Laboratory, Campus de Luminy, 13288 Marseille (France); Ion, V. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Faculty of Physics, University of Bucharest, 077125 Magurele (Romania); Rusen, L.; Filipescu, M. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering – IFIN HH, Magurele, Bucharest (Romania); Luculescu, C.; Dinescu, M. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania)

    2015-10-15

    Highlights: • Roughness gradients are obtained in one step by applying single laser pulses and sample tilting. • BSA protein and cell dependence behavior onto gradient characteristics was studied. • The degradation of the samples by lysozyme was correlated to its ability to access the textured area. - Abstract: Surface modifications of biocompatible materials are among the main factors used for enhancing and promoting specific cellular activities (e.g. spreading, adhesion, migration, and differentiation) for various types of medical applications such as implants, microfluidic devices, or tissue engineering scaffolds. In this work an excimer laser at 193 nm was used to fabricate chitosan–collagen roughness gradients. The roughness gradients were obtained in one step by applying single laser pulses and sample tilting. Fourier transform infrared spectroscopy measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and spectro-ellipsometry (SE) were used for sample characterization. The goal is to determine the optimal morpho-chemical characteristics of these structures for in vitro tailoring of protein adsorption and cell behavior. The response induced by the roughness gradient onto various cell lines (i.e. L 929 fibroblasts, HEP G2 hepatocytes, OLN 93 oligodendrocytes, M63 osteoblasts) and bovine serum albumin (BSA) protein absorption was investigated.

  8. Surface morphologies of excimer-laser annealed BF2+ implanted Si diodes

    International Nuclear Information System (INIS)

    Burtsev, A.; Schut, H.; Nanver, L.K.; Veen, A. van; Slabbekoorn, J.; Scholtes, T.L.M.

    2004-01-01

    Laser-induced surface roughness and damage formation in ultra-shallow n + -p and p + -n junctions, formed by low energy (5 keV) As + and BF 2 + implantations in Si, respectively, with a dose of 1 x 10 15 cm -2 have been investigated by atomic force microscopy (AFM) and Positron Annihilation Doppler Broadening (PADB) technique. The Si surface roughness is found to increase with laser energy density, and reaches a value of 3.5 nm after excimer-laser annealing (ELA) at 1100 mJ/cm 2 . However, anomalous behavior is witnessed for BF 2 + -implanted Si sample at 800 mJ/cm 2 , at which energy very high surface protrusions up to 9 nm high are observed. By PADB this behavior is correlated to extensive deep microcavity formation in the Si whereby the volatile F 2 fraction can accumulate and evaporate/out-diffuse, leading to Si surface roughening. The consequences for the diode characteristics and contact resistivity are examined

  9. Excimer lasers utilizing XeF and XeCl molecules

    Energy Technology Data Exchange (ETDEWEB)

    Bychkov, Yu I; Konovalov, I N; Losev, V F; Mesyats, G A; Ryzhov, V V; Tarasenko, V F; Fedorov, A I; Shemyakina, S B; Yastremskii, A G

    1978-12-01

    The results are given of an experimental and theoretical study of XeF (wavelength approx. 350 nm) and XeCl (wavelength approx. 308 nm) lasers excited by an electron beam, a discharge stabilized by an electron beam, and a rapid discharge. These lasers are representative of ones employing halides of noble gases, which are the most powerful sources of stimulated emission in the uv region. The XeCl laser is shown to have good emission characteristics with various methods of excitation. An analysis of the kinetics of processes in the plasma of lasers utilizing halides of noble gases showed that the main channel for the transfer of the beam's energy to the formation of excimer molecules is the ionic channel. An efficiency of about 2.6 percent and a specific radiant energy of 10 J.l/sup -1/ showed that XeCl* is one of the most effective excimer molecules.

  10. Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

    OpenAIRE

    O. Van Overschelde; G. Guisbiers; R. Snyders

    2013-01-01

    Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA) in de-ionized water. Excimer laser (248 nm) operating at low fluence (F ∼ 1 J/cm2) was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the cen...

  11. A design of energy detector for ArF excimer lasers

    Science.gov (United States)

    Feng, Zebin; Han, Xiaoquan; Zhou, Yi; Bai, Lujun

    2017-08-01

    ArF excimer lasers with short wavelength and high photon energy are widely applied in the field of integrated circuit lithography, material processing, laser medicine, and so on. Excimer laser single pulse energy is a very important parameter in the application. In order to detect the single pulse energy on-line, one energy detector based on photodiode was designed. The signal processing circuit connected to the photodiode was designed so that the signal obtained by the photodiode was amplified and the pulse width was broadened. The amplified signal was acquired by a data acquisition card and stored in the computer for subsequent data processing. The peak of the pulse signal is used to characterize the single pulse energy of ArF excimer laser. In every condition of deferent pulse energy value levels, a series of data about laser pulses energy were acquired synchronously using the Ophir energy meter and the energy detector. A data set about the relationship between laser pulse energy and the peak of the pulse signal was acquired. Then, by using the data acquired, a model characterizing the functional relationship between the energy value and the peak value of the pulse was trained based on an algorithm of machine learning, Support Vector Regression (SVR). By using the model, the energy value can be obtained directly from the energy detector designed in this project. The result shows that the relative error between the energy obtained by the energy detector and by the Ophir energy meter is less than 2%.

  12. UV excimer laser and low temperature plasma treatments of polyamide materials

    Science.gov (United States)

    Yip, Yiu Wan Joanne

    Polyamides have found widespread application in various industrial sectors, for example, they are used in apparel, home furnishings and similar uses. However, the requirements for high quality performance products are continually increasing and these promote a variety of surface treatments for polymer modification. UV excimer laser and low temperature plasma treatments are ideally suited for polyamide modification because they can change the physical and chemical properties of the material without affecting its bulk features. This project aimed to study the modification of polyamides by UV excimer laser irradiation and low temperature plasma treatment. The morphological changes in the resulting samples were analysed by scanning electron microscopy (SEM) and tapping mode atomic force microscopy (TM-AFM). The chemical modifications were studied by x-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and chemical force microscopy (CFM). Change in degree of crystallinity was examined by differential scanning calorimetry (DSC). After high-fluence laser irradiation, topographical results showed that ripples of micrometer size form on the fibre surface. By contrast, sub-micrometer size structures form on the polyamide surface when the applied laser energy is well below its ablation threshold. After high-fluence laser irradiation, chemical studies showed that the surface oxygen content of polyamide is reduced. A reverse result is obtained with low-fluence treatment. The DSC result showed no significant change in degree of crystallinity in either high-fluence or low-fluence treated samples. The same modifications in polyamide surfaces were studied after low temperature plasma treatment with oxygen, argon or tetrafluoromethane gas. The most significant result was that the surface oxygen content of polyamide increased after oxygen and argon plasma treatments. Both treatments induced many hydroxyl (-OH) and carboxylic acid (-COOH

  13. Excimer laser assisted re-oxidation of BaTiO3 thin films on Ni metal foils

    International Nuclear Information System (INIS)

    Bharadwaja, S. S. N.; Ko, S. W.; Qu, W.; Clark, T.; Rajashekhar, A.; Motyka, M.; Podraza, N.; Randall, C. A.; Trolier-McKinstry, S.

    2016-01-01

    Excimer laser assisted re-oxidation for reduced, crystallized BaTiO 3 thin films on Ni-foils was investigated. It was found that the BaTiO 3 can be re-oxidized at an oxygen partial pressure of ∼50 mTorr and substrate temperature of 350 °C without forming a NiO x interface layer between the film and base metal foil. The dielectric permittivity of re-oxidized films was >1000 with loss tangent values <2% at 100 Hz, 30 mV rms excitation signal. Electron Energy Loss Spectroscopy indicated that BaTiO 3 thin films can be re-oxidized to an oxygen stoichiometry close to ∼3 (e.g., stoichiometric). High resolution cross sectional transmission electron microscopy showed no evidence of NiO x formation between the BaTiO 3 and the Ni foil upon excimer laser re-oxidation. Spectroscopic ellipsometry studies on laser re-oxidized [001] C and [111] C BaTiO 3 single crystals indicate that the re-oxidation of BaTiO 3 single crystals is augmented by photo-excitation of the ozone, as well as laser pulse induced temperature and local stress gradients

  14. Change of wettability of PTFE surface by sputter etching and excimer laser. Sputter etching oyobi excimer laser ni yoru PTFE hyomen no shinsuika

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, S. (Nitto Denko Corp., Osaka (Japan)); Kubo, U. (Kinki University, Osaka (Japan))

    1994-06-20

    The wettability of PTFE (polytetrafluoroethylene) surfaces was improved by sputter etching and excimer laser irradiation. In sputter etching, the PTFE surface was treated by reactive sputter etching with H2O gas to give active groups on the surface. In laser irradiation, the surface was irradiated in pure water by high-energy KrF excimer laser. As the surface wettability was evaluated with a contact angle to water, the contact angle decreased remarkably in both treatments resulting in a good improvement effect. In sputter etching, various new chemical bonds such as F-C=O, F2C-FC-O, F2C-C-O and C-O were observed because of a decrease in F and incorporation of oxygen. Such chemical bonds could be eliminated by ultraviolet ray irradiation, and the treated surface condition approached the initial condition after irradiation of 200 hours. In laser irradiation, it was suggested that C-F bonds were broken, and OH groups were added to the surface by dissociation of H2O to H and OH. 7 refs., 8 figs., 1 tab.

  15. Influence of Selected Parameters of XeCl Excimer Laser System on Characteristics of Radiation Pulses

    International Nuclear Information System (INIS)

    Pokora, L.; Iwanejko, L.

    1998-01-01

    We present the dependences of energy and duration of radiation pulses as well as efficiency of XeCl laser on selected parameters of the laser system such as: C 2 capacitance, the separating inductance, L S , the distance between electrodes in laser's chamber, d K and also the supply voltage, U 0 , composition, and pressure of the active-medium mixture of gases. Results of numerical computations relate to a three-component mixture of gases, He-Xe-HCl, of the active medium of the excimer laser. (author)

  16. Comparative study of excimer and erbium:YAG lasers for ablation of structural components of the knee

    Science.gov (United States)

    Vari, Sandor G.; Shi, Wei-Qiang; van der Veen, Maurits J.; Fishbein, Michael C.; Miller, J. M.; Papaioannou, Thanassis; Grundfest, Warren S.

    1991-05-01

    This study was designed to compare the efficiency and thermal effect of a 135 ns pulsed-stretched XeCl excimer laser (308 nm) and a free-running Erbium:YAG laser (2940 nm) with 200 microsecond(s) pulse duration for ablation of knee joint structures (hyaline and fibrous cartilage, tendon and bone). The radiant exposure used for tissue ablation ranged from 2 to 15 J/cm2 for the XeCl excimer and from 33 to 120 J/cm2 for Er:YAG. The excimer and Er:YAG lasers were operated at 4 and 5 Hz respectively. The ablative laser energy was delivered to tissue through fibers. Ablation rates of soft tissues (hyaline and fibrous cartilage, tendon) varied from 8.5 to 203 micrometers /pulse for excimer and from 8.2 to 273 micrometers /pulse for Er:YAG lasers. Ablation rates of soft tissues are linearly dependent on the radiant exposure. Within the range of parameters tested all the tissues except the bone could be rapidly ablated by both lasers. Bone ablation was much less efficient, requiring 15 J/cm2 and 110 J/cm2 radiant exposure for excimer and Er:YAG lasers to ablate 9.5 and 8.2 micrometers tissue per pulse. However, excimer laser ablation produced less thermal damage in the tissues studied compared to Er:YAG at the same laser parameters. The authors conclude that both lasers are capable of efficient knee joint tissue ablation. XeCl excimer laser requires an order of magnitude less energy than Er:YAG laser for comparable tissue ablation.

  17. 308-nm excimer laser for the treatment of alopecia areata in children.

    Science.gov (United States)

    Al-Mutairi, Nawaf

    2009-01-01

    Alopecia areata (AA) is a common skin disease which is characterized by nonscarring localized or diffused hair loss. In this study we assessed the efficacy of 308-nm Excimer laser in the treatment of alopecia areata in children. A total of 9 children with 30 recalcitrant patches alopecia areata and two children with alopecia areata totalis were enrolled in this study which included seven male and four female patients, aged between 4 and 14 years and the durations of their disease were between 7 and 25 months. All of these patients had more than one lesion of alopecia areata and at least one of them was left as a control for comparison. The lesions were treated with the 308-nm Excimer laser twice a week for a period of 12 weeks. Regrowth of hair was observed in 18 (60%) alopecia patches in the scalp, while there was no response in the control patches and over the extremities. Only four patients with scalp lesions showed a recurrence of alopecia after 6 months post laser therapy. So, 308-nm Excimer laser is considered an effective safe therapeutic option for patchy alopecia areata in children.

  18. Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

    International Nuclear Information System (INIS)

    Gontad, F.; Conde, J.C.; Filonovich, S.; Cerqueira, M.F.; Alpuim, P.; Chiussi, S.

    2013-01-01

    We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p + -nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm 2 is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm 2 promote partial crystallization of the amorphous structures

  19. Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Gontad, F., E-mail: fran_gontad@yahoo.es [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Conde, J.C. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Filonovich, S.; Cerqueira, M.F.; Alpuim, P. [Department of Physics, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); Chiussi, S. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain)

    2013-06-01

    We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p{sup +}-nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm{sup 2} is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm{sup 2} promote partial crystallization of the amorphous structures.

  20. Clinical results of PRK touch-up using Chiron/Technolas Keracor 116 excimer laser

    Science.gov (United States)

    Davidian, Mary E.; Keates, Richard H.; Ren, Qiushi

    1995-05-01

    Regression of effect as well as undercorrection are well established complications of excimer photorefractive keratectomy for the correction of myopia. In thirteen eyes initially treated with the VISX Taunton excimer laser and then retreated with the Chiron Technolas laser, the minimum follow-up time was six months. The mean postoperative refraction at six months was -0.442 +/- 0.996 D (diopters), significantly different from the pretreatment mean of -1.904 +/- 1.297 D. At six months after retreatment (10/13 eyes) 76.9% had an uncorrected visual acuity greater than or equal to 20/40 and (10/13 eyes) 76.9% were within 1 diopter of emmetropia. Only one eye had a significant increase in postoperative haze. The results of this study indicate that the majority of photorefractive keratectomy regressions and undercorrections can be successfully retreated.

  1. X-ray photoelectron spectroscopy study of excimer laser treated alumina films

    Science.gov (United States)

    Georgiev, D. G.; Kolev, K.; Laude, L. D.; Mednikarov, B.; Starbov, N.

    1998-01-01

    Amorphous alumina layers are deposited on a single crystal Si substrate by a e-gun evaporation technique. These films are then thermally annealed in oxygen to be crystallized and, further, irradiated with an excimer laser beam. At each stage of the film preparation, an x-ray photoelectron spectroscopy analysis is performed at the film surface and in depth, upon ion beam grinding. Results give evidence for the formation of an aluminosilicate upon thermal annealing of the film in oxygen. At the surface itself, this compound is observed to decompose upon excimer laser irradiation at energy densities exceeding 1.75 J/cm2, giving rise to free Si atoms and SiO2, however with complete disappearance of Al atoms. Model photochemical reactions are proposed to explain such transformations.

  2. Periodic morphological modification developed on the surface of polyethersulfone by XeCl excimer laser photoablation

    International Nuclear Information System (INIS)

    Niino, H.; Nakano, M.; Nagano, S.; Yabe, A.; Miki, T.; Center for Structure Analyses, Teijin Limited, Asahigaoka, Hino, Tokyo, 191 Japan)

    1989-01-01

    Periodic and stable micropatterns appeared on the surface of amorphous polyethersulfone etched with an excimer laser at 308 nm in ambient air and a vacuum. The control of such radiative conditions as fluence and incident angle enables us to modify the spacing and pattern of the microstructures. A topographical investigation with scanning electron microscopy and an experiment with x-ray photoelectron spectroscopy to determine its composition is reported

  3. Improved model for the angular dependence of excimer laser ablation rates in polymer materials

    Science.gov (United States)

    Pedder, J. E. A.; Holmes, A. S.; Dyer, P. E.

    2009-10-01

    Measurements of the angle-dependent ablation rates of polymers that have applications in microdevice fabrication are reported. A simple model based on Beer's law, including plume absorption, is shown to give good agreement with the experimental findings for polycarbonate and SU8, ablated using the 193 and 248 nm excimer lasers, respectively. The modeling forms a useful tool for designing masks needed to fabricate complex surface relief by ablation.

  4. Does imiquimod pretreatment optimize 308-nm excimer laser (UVB) therapy in psoriasis patients?

    Science.gov (United States)

    Tacastacas, Joselin D; Oyetakin-White, Patricia; Soler, David C; Young, Andrew; Groft, Sarah; Honda, Kord; Cooper, Kevin D; McCormick, Thomas S

    2017-07-01

    Psoriasis continues to be a debilitating skin disease affecting 1-3% of the United States population. Although the effectiveness of several current biologic therapies have described this pathology as a IL-23, TNF-a and Th17-mediated disease, less invasive approaches are still in use and in need of refinement. One of these is the usage of narrow band-UVB (NB-UVB) therapy to deplete specifically intra-epidermal CD3+, CD4+ and CD8+ cells to clear psoriatic plaques. In order to improve NB-UVB therapy, we sought to determine whether skin pre-treatment with the TLR7 agonist imiquimod (IMQ) would help increase the efficiency of the former at resolving psoriatic plaques. Eucerin ® Original Moisturizing Lotion (topical vehicle) or Aldara ® (imiquimod 5% topical cream) were applied for 5 days once daily to a maximum contiguous area of 25 cm 2 (5 cm × 5 cm area). Patients were provided with sachets containing 12.5 mg of imiquimod each and were instructed to apply imiquimod (I) to two psoriasis plaques (5 sachets of imiquimod allotted to each plaque). A PHAROS excimer Laser EX-308 (Ra Medical Systems, Inc. Carlsbad, CA, USA) with an output of monochromatic 308-nm light and pulse width of 20-50 ns was used for all patients. Punch biopsies of psoriatic lesions (6 mm) were taken at 4 and 48 h after final application of topical treatment with or without excimer laser treatment. Real-time quantitative RT-PCR was performed according to manufacturer's instructions and Inmunohistochemistry was used as described before. Our results suggests that although IMQ seemed to activate the type I interferon pathway as previously described, its concomitant usage with NB-UVB for clearing psoriatic skin was ineffective. Although upregulation of genes MxA, GRAMD1A and DMXL2 suggested that IMQ treatment did induce skin changes in psoriasis patients, more optimal dosing of IMQ and NB-UVB might be necessary to achieve desired treatment responses. The observation that psoriasis involvement was not

  5. LASIK for myopia and astigmatism using the SCHWIND AMARIS excimer laser: an international multicenter trial.

    Science.gov (United States)

    Arbelaez, Maria Clara; Aslanides, Ioannis M; Barraquer, Carmen; Carones, Francesco; Feuermannova, Alena; Neuhann, Tobias; Rozsival, Pavel

    2010-02-01

    To assess the efficacy, predictability, and safety of LASIK for the surgical correction of low to moderate myopia with astigmatism using the SCHWIND AMARIS excimer laser. Six international study sites enrolled 358 eyes with a manifest refraction spherical equivalent (MRSE) from -0.50 to -7.38 diopters (D) (mean sphere: -3.13+/-1.58 D) with up to -5.00 D of astigmatism (mean: -0.69+/-0.67 D). All eyes underwent treatment with the nonwavefront-guided aspheric algorithm of the SCHWIND AMARIS excimer laser. All eyes were targeted for emmetropia. Refractive outcomes and corneal higher order aberrations were analyzed pre- and postoperatively. Visual quality was assessed using photopic and mesopic contrast sensitivity. Six-month postoperative outcomes are reported. At 6 months postoperative, the MRSE for all eyes was -0.21+/-0.20 D, and 96% (343/358) of eyes had MRSE within +/-0.50 D. Uncorrected visual acuity was 20/20 or better in 98% (351/358) of eyes, and no eyes lost 2 or more lines of best spectacle-corrected visual acuity. The total corneal higher order aberrations root-mean-square increased by 0.09 microm, spherical aberration increased by 0.08 microm, and coma increased by 0.04 microm postoperatively. Photopic and mesopic contrast sensitivity did not change 6 months postoperatively. Treatment of myopia with astigmatism using the SCHWIND AMARIS excimer laser is safe, efficacious, predictable, and maintains visual quality.

  6. Comparison of KrF and ArF excimer laser treatment of biopolymer surface

    Energy Technology Data Exchange (ETDEWEB)

    Michaljaničová, I. [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Slepička, P., E-mail: petr.slepicka@vscht.cz [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Heitz, J.; Barb, R.A. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Sajdl, P. [Department of Power Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Švorčík, V. [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic)

    2015-06-01

    Highlights: • The influence of ArF and KrF laser on biopolymer surface was determined. • ArF laser acts predominantly on biopolymer surface. • PHB roughness is increased similarly for both applied wavelengths. • Roughness of nanostructures can be precisely controlled. • ArF laser introduces nitrogen on PHB surface. - Abstract: The goal of this work was the investigation of the impact of two different excimer lasers on two biocompatible and biodegradable polymers (poly-L-lactide and poly hydroxybutyrate). Both polymers find usage in medical and pharmaceutical fields. The polymers were modified by KrF and ArF excimer lasers. Subsequently the impact on surface morphology, surface chemistry changes, and thermal properties was studied by means of confocal and AFM microscopy, FTIR and XPS spectroscopy and DSC calorimetry. Under the same conditions of laser treatment it was observed that ArF laser causes more significant changes on surface chemistry, surface morphology and pattern formation on the polymers under investigation. The data obtained in this work can be used for a wide range of possible applications, in tissue engineering or in combination with metallization in electronics, e.g. for biosensors.

  7. Excimer laser correction of hyperopia, hyperopic and mixed astigmatism: past, present, and future.

    Science.gov (United States)

    Lukenda, Adrian; Martinović, Zeljka Karaman; Kalauz, Miro

    2012-06-01

    The broad acceptance of "spot scanning" or "flying spot" excimer lasers in the last decade has enabled the domination of corneal ablative laser surgery over other refractive surgical procedures for the correction of hyperopia, hyperopic and mixed astigmatism. This review outlines the most important reasons why the ablative laser correction of hyperopia, hyperopic and mixed astigmatism for many years lagged behind that of myopia. Most of today's scanning laser systems, used in the LASIK and PRK procedures, can safely and effectively perform low, moderate and high hyperopic and hyperopic astigmatic corrections. The introduction of these laser platforms has also significantly improved the long term refractive stability of hyperopic treatments. In the future, further improvements in femtosecond and nanosecond technology, eye-tracker systems, and the development of new customized algorithms, such as the ray-tracing method, could additionally increase the upper limit for the safe and predictable corneal ablative laser correction ofhyperopia, hyperopic and mixed astigmatism.

  8. Ultraviolet excimer laser ablation: the effect of wavelength and repetition rate on in vivo guinea pig skin

    Energy Technology Data Exchange (ETDEWEB)

    Morelli, J.; Kibbi, A.G.; Farinelli, W.; Boll, J.; Tan, O.T.

    1987-06-01

    Multiple dermatologic conditions that are currently treated with traditional cold-knife surgery are amenable to laser therapy. The ideal surgical treatment would be precise and total removal of abnormal tissue with maximal sparing of remaining structures. The ultraviolet (UV) excimer laser is capable of such precise tissue removal due to the penetration depth of 193 nm and 248 nm irradiation of 1 micron per pulse. This type of ablative tissue removal requires a high repetition rate for efficient lesional destruction. Excimer laser radiation at 193 nm is capable of high repetition rates, which are necessary while 248 nm radiation causes increasing nonspecific thermal injury as the laser repetition rate is increased.

  9. The development and progress of XeCl Excimer laser system

    Science.gov (United States)

    Zhang, Yongsheng; Ma, Lianying; Wang, Dahui; Zhao, Xueqing; Zhu, Yongxiang; Hu, Yun; Qian, Hang; Shao, Bibo; Yi, Aiping; Liu, Jingru

    2015-05-01

    A large angularly multiplexed XeCl Excimer laser system is under development at the Northwest Institute of Nuclear Technology (NINT). It is designed to explore the technical issues of uniform and controllable target illumination. Short wavelength, uniform and controllable target illumination is the fundamental requirement of high energy density physics research using large laser facility. With broadband, extended light source and multi-beam overlapping techniques, rare gas halide Excimer laser facility will provide uniform target illumination theoretically. Angular multiplexing and image relay techniques are briefly reviewed and some of the limitations are examined to put it more practical. The system consists of a commercial oscillator front end, three gas discharge amplifiers, two electron beam pumped amplifiers and the optics required to relay, encode and decode the laser beam. An 18 lens array targeting optics direct and focus the laser in the vacuum target chamber. The system is operational and currently undergoing tests. The total 18 beams output energy is more than 100J and the pulse width is 7ns (FWHM), the intensities on the target will exceed 1013W/cm2. The aberration of off-axis imaging optics at main amplifier should be minimized to improve the final image quality at the target. Automatic computer controlled alignment of the whole system is vital to efficiency and stability of the laser system, an array of automatic alignment model is under test and will be incorporated in the system soon.

  10. Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

    Directory of Open Access Journals (Sweden)

    O. Van Overschelde

    2013-10-01

    Full Text Available Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA in de-ionized water. Excimer laser (248 nm operating at low fluence (F ∼ 1 J/cm2 was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the centrifugation method to isolate the smallest nanoparticles (∼60 nm in diameter.

  11. Perspectives and advantages of the use of excimer laser annealing for MOS technology

    International Nuclear Information System (INIS)

    Privitera, V.; Alippi, P.; Camalleri, M.

    2006-01-01

    The integration of excimer laser annealing (ELA) into the MOS device technology has been studied and evaluated within the frame of the IST project FLASH (Fundamentals and applications of laser processing for highly innovative MOS technology), funded by the European Commission. The final aim of the project was to demonstrate that ELA can be applied as a reliable, effective and advantageous process in the context of semiconductor device fabrication. Some of the results of this activity are summarised, relative to the experimental characterization and theoretical modelling. The electrical characterization of the transistor fabricated by ELA is also presented, showing a device yield of 90% on wafer

  12. Offset-gated poly-Si TFTs using in-situ fluorine passivation and excimer laser doping

    International Nuclear Information System (INIS)

    Jung, Sang Hoon; Kim, Cheon Hong; Yoo, Juhn Suk; Han, Min Koo

    2000-01-01

    A new low-temperature poly-Si thin film transistor (TFT) fabrication method employing in-situ fluorine passivation and excimer-laser doping is proposed to fabricate offset-gated poly-Si TFTs. In the new process, the crystallization, the in-situ fluorine passivation of the active layer, and the doping of the source/drain region are performed simultaneously with only one step of excimer laser annealing while the conventional fabrication method requires two laser annealing steps. Employing phosphosilicate glass (PSG) films as a diffusion source, we successfully accomplished excimer laser doping. The subthreshold and the on-state characteristics of the device with in-situ fluorine passivation were considerably improved. This improvement was due to the fluorine passivation effects, which cured dangling bonds and strained bonds in the poly-Si channel, the offset region, and the SiO 2 /poly-Si interface

  13. Offset-gated poly-Si TFTs using in-situ fluorine passivation and excimer laser doping

    CERN Document Server

    Jung, S H; Yoo, J S; Han, M K

    2000-01-01

    A new low-temperature poly-Si thin film transistor (TFT) fabrication method employing in-situ fluorine passivation and excimer-laser doping is proposed to fabricate offset-gated poly-Si TFTs. In the new process, the crystallization, the in-situ fluorine passivation of the active layer, and the doping of the source/drain region are performed simultaneously with only one step of excimer laser annealing while the conventional fabrication method requires two laser annealing steps. Employing phosphosilicate glass (PSG) films as a diffusion source, we successfully accomplished excimer laser doping. The subthreshold and the on-state characteristics of the device with in-situ fluorine passivation were considerably improved. This improvement was due to the fluorine passivation effects, which cured dangling bonds and strained bonds in the poly-Si channel, the offset region, and the SiO sub 2 /poly-Si interface.

  14. XeCl excimer laser with new prism resonator configurations and its performance characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Benerji, N. S., E-mail: nsb@rrcat.gov.in, E-mail: bsingh@rrcat.gov.in; Singh, A.; Varshnay, N.; Singh, Bijendra, E-mail: nsb@rrcat.gov.in, E-mail: bsingh@rrcat.gov.in [Excimer Laser Section, LMPD, Raja Ramanna Center for Advanced Technology, Indore 452013 (India)

    2015-07-15

    New resonator cavity configurations, namely, the prism resonator and unstable prism resonator, are demonstrated for the first time in an excimer (XeCl) laser with interesting and novel results. High misalignment tolerance ∼50 mrad is achieved with considerably reduced beam divergence of less than ∼1 mrad without reduction in output power capabilities of the laser. The misalignment tolerance of ∼50 mrad is a dramatic improvement of ∼25 times compared to ∼2 mrad normally observed in standard excimer laser with plane-plane cavity. Increase in depth of focus from 3 mm to 5.5 mm was also achieved in case of prism resonator configuration with an improvement of about 60%. Unstable prism resonator configuration is demonstrated here in this paper with further reduction in beam divergence to about 0.5 mrad using plano-convex lens as output coupler. The misalignment tolerance in case of unstable prism resonator was retained at about 30 mrad which is a high value compared to standard unstable resonators. The output beam spot was completely filled with flat-top profile with prism resonator configurations, which is desired for various material processing applications. Focusing properties and beam divergence in case of prism resonator have been investigated using SEM (scanning electron microscope) images. SEM images of the focused spot size (∼20 μm holes) on metal sheet indicate beam divergence of about 0.05 mrad which is about 1.5 times diffraction limit. Energy contained in this angle is thus sufficient for micro-machining applications. Clean and sharp edges of the micro-holes show high pointing stability with multiple shot exposures. Such characteristics of the excimer laser system will be extremely useful in micro-machining and other field applications.

  15. Early outcome of high energy Laser (Excimer) facilitated coronary angioplasty ON hARD and complex calcified and balloOn-resistant coronary lesions: LEONARDO Study

    International Nuclear Information System (INIS)

    Ambrosini, Vittorio; Sorropago, Giovanni; Laurenzano, Eugenio; Golino, Luca; Casafina, Alfredo; Schiano, Vittorio; Gabrielli, Gabriele; Ettori, Federica; Chizzola, Giuliano; Bernardi, Guglielmo; Spedicato, Leonardo; Armigliato, Pietro; Spampanato, Carmine; Furegato, Martina

    2015-01-01

    Aim: An innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) has been recently used for the treatment of complex coronary lesions, as calcified stenosis, chronic total occlusions and non-compliant plaques. Such complex lesions are difficult to adequately treat with balloon angioplasty and/or intracoronary stenting. The aim of this study was to examine the acute outcome of this approach on a cohort of patients with coronary lesions. Methods and Results: Eighty patients with 100 lesions were enrolled through four centers, and excimer laser coronary angioplasty was performed on 96 lesions (96%). Safety and effectiveness data were compared between patients treated with standard laser therapy and those treated with increased laser therapy. Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success in was obtained in 87 lesions (90.6%). There was no perforation, major side branch occlusion, spasm, no-reflow phenomenon, dissection nor acute vessel closure. Increased laser parameters were used successfully for 49 resistant lesions without complications. Conclusions: This study suggests that laser-facilitated coronary angioplasty is a simple, safe and effective device for the management of complex coronary lesions. Furthermore, higher laser energy levels delivered by this catheter improved the device performance without increasing complications. - Highlights: • We planned this multicenter study to examine the acute outcome of an innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) for treatment of complex coronary lesions. • We enrolled 80 patients with 100 lesions and performed excimer laser coronary angioplasty in 96 lesions (96%). • Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success was obtained in 87 lesions (90.6%). • Increased laser parameters were used successfully for 49 resistant

  16. Early outcome of high energy Laser (Excimer) facilitated coronary angioplasty ON hARD and complex calcified and balloOn-resistant coronary lesions: LEONARDO Study

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosini, Vittorio; Sorropago, Giovanni; Laurenzano, Eugenio [Montevergine Clinic, Mercogliano (Italy); Golino, Luca, E-mail: lucagolino.jazz@alice.it [Montevergine Clinic, Mercogliano (Italy); Moriggia-Pelascini Hospital, Gravedona, Como (Italy); Casafina, Alfredo; Schiano, Vittorio [Montevergine Clinic, Mercogliano (Italy); Gabrielli, Gabriele [University Hospital Ospedali Riuniti, Ancona (Italy); Ettori, Federica; Chizzola, Giuliano [Spedali Civili University Hospital, Brescia (Italy); Bernardi, Guglielmo; Spedicato, Leonardo [University Hospital S. Maria Misericordia, Udine (Italy); Armigliato, Pietro [Istituto Italiano Ricerche Mediche, Verona (Italy); Spampanato, Carmine [Telethon Institute of Genetics and Medicine (TIGEM), Naples (Italy); Furegato, Martina [Istituto Italiano Ricerche Mediche, Verona (Italy)

    2015-04-15

    Aim: An innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) has been recently used for the treatment of complex coronary lesions, as calcified stenosis, chronic total occlusions and non-compliant plaques. Such complex lesions are difficult to adequately treat with balloon angioplasty and/or intracoronary stenting. The aim of this study was to examine the acute outcome of this approach on a cohort of patients with coronary lesions. Methods and Results: Eighty patients with 100 lesions were enrolled through four centers, and excimer laser coronary angioplasty was performed on 96 lesions (96%). Safety and effectiveness data were compared between patients treated with standard laser therapy and those treated with increased laser therapy. Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success in was obtained in 87 lesions (90.6%). There was no perforation, major side branch occlusion, spasm, no-reflow phenomenon, dissection nor acute vessel closure. Increased laser parameters were used successfully for 49 resistant lesions without complications. Conclusions: This study suggests that laser-facilitated coronary angioplasty is a simple, safe and effective device for the management of complex coronary lesions. Furthermore, higher laser energy levels delivered by this catheter improved the device performance without increasing complications. - Highlights: • We planned this multicenter study to examine the acute outcome of an innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) for treatment of complex coronary lesions. • We enrolled 80 patients with 100 lesions and performed excimer laser coronary angioplasty in 96 lesions (96%). • Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success was obtained in 87 lesions (90.6%). • Increased laser parameters were used successfully for 49 resistant

  17. Excimer laser-assisted anterior lamellar keratoplasty for keratoconus, corneal problems after laser in situ keratomileusis, and corneal stromal opacities.

    Science.gov (United States)

    Bilgihan, Kamil; Ozdek, Sengül C; Sari, Ayça; Hasanreisoğlu, Berati

    2006-08-01

    To evaluate excimer laser-assisted anterior lamellar keratoplasty to augment thin corneas as in keratoconus ( .05). This technique presents a different modality for the treatment of keratoconus, post-LASIK corneal problems, and other corneal stromal opacities with anterior lamellar keratoplasty. Additional studies with more patients and longer follow-up will help determine the role of this technique as a substitute for penetrating keratoplasty in these patients.

  18. Random noise can help to improve synchronization of excimer laser pulses.

    Science.gov (United States)

    Mingesz, Róbert; Barna, Angéla; Gingl, Zoltán; Mellár, János

    2016-02-01

    Recently, we have reported on a compact microcontroller-based unit developed to accurately synchronize excimer laser pulses (Mingesz et al. 2012 Fluct. Noise Lett. 11, 1240007 (doi:10.1142/S021947751240007X)). We have shown that dithering based on random jitter noise plus pseudorandom numbers can be used in the digital control system to radically reduce the long-term drift of the laser pulse from the trigger and to improve the accuracy of the synchronization. In this update paper, we present our new experimental results obtained by the use of the delay-controller unit to tune the timing of a KrF excimer laser as an addition to our previous numerical simulation results. The hardware was interfaced to the laser using optical signal paths in order to reduce sensitivity to electromagnetic interference and the control algorithm tested by simulations was applied in the experiments. We have found that the system is able to reduce the delay uncertainty very close to the theoretical limit and performs well in real applications. The simple, compact and flexible system is universal enough to also be used in various multidisciplinary applications.

  19. A 223-nm KrCl excimer laser on a He-Kr-HCl mixture

    International Nuclear Information System (INIS)

    Razhev, A M; Zhupikov, A A; Kargapol'tsev, E S

    2004-01-01

    The results of experimental studies of the parameters of a 223-nm electric-discharge KrCl excimer laser on a He-Kr-HCl mixture depending on the excitation conditions and the composition of the active gaseous medium are presented. To achieve the maximum values of the output energy and the efficiency of the KrCl laser on mixtures with buffer gaseous helium, an excitation system was used that included a circuit with an LC inverter with a high-voltage switch based on an RU-65 spark gap. An output energy of 320 mJ with an efficiency of 0.5% relative to the energy stored in the capacitors is obtained in a KrCl laser with an active medium based on the buffer He gas at a charging voltage of 30 kV. Radiation pulses with a duration of 22±1 ns and a pulse power of 15 MW are obtained. (lasers)

  20. Polycrystalline diamond film UV detectors for excimer lasers

    International Nuclear Information System (INIS)

    Ralchenko, V G; Savel'ev, A V; Konov, Vitalii I; Mazzeo, G; Spaziani, F; Conte, G; Polyakov, V I

    2006-01-01

    Photoresistive metal-semiconductor-metal detectors based on polycrystalline diamond films are fabricated for recording cw and pulsed UV radiation. The detectors have a high spectral selectivity (the UV-to-VIS response ratio is ∼10 5 ) and a temporal resolution of the order of 10 9 s. 'Solar-blind' photostable diamond detectors are promising for applications in UV lithography, laser micromachining, medicine, and space research. (letters)

  1. An experimental study on laser drilling and cutting of composite materials for the aerospace industry using excimer and CO2 sources

    Science.gov (United States)

    dell'Erba, M.; Galantucci, L. M.; Miglietta, S.

    This paper reports on the results of research which investigated the potential for the application of an excimer laser in the field of composite material drilling and cutting, by comparing this technology with that using CO2 sources. In particular, the scope of the work was to check whether the interaction between excimer lasers and composite materials, whose characteristic feature is the absence of thermal transfer, could yield better results than those obtainable with CO2 sources once heat transfer-induced difficulties had been eliminated. The materials selected for the experiments were multilayer composites having an epoxy resin matrix (65 percent in volume), with aramid fiber (Kevlar), carbon fiber and glass fiber as reinforcing materials, all of considerable interest for the aerospace industry. Optimal operational parameters were identified in relation to each source with a view to obtaining undersize holes or through cuts exhibiting severed areas of good quality. A comparison between the two types of processing carried out show that rims processed by excimer lasers are of better quality - particularly so with Kevlar - whereas the ablation rate is undoubtedly rather low compared with the CO2 technology.

  2. Optical coherence tomography following percutaneous coronary intervention with Excimer laser coronary atherectomy

    Energy Technology Data Exchange (ETDEWEB)

    Rawlins, John, E-mail: john.rawlins@doctors.net.uk; Talwar, Suneel; Green, Mark; O’Kane, Peter

    2014-01-15

    The indications for Excimer laser coronary atherectomy (ELCA) have been refined in modern interventional practice. With the expanding role for optical coherence tomography (OCT) providing high-resolution intra-coronary imaging, this article examines the appearance of the coronary lumen after ELCA. Each indication for ELCA is discussed and illustrated with a clinical case, followed by detailed analysis of the OCT imaging pre and post ELCA. The aim of the article is to provide information to interventional cardiologists to facilitate decision making during PCI, when ELCA has been used as part of the interventional strategy.

  3. Impact of Angioscopic Evaluation for Femoropopliteal In-Stent Restenosis Before and After Excimer Laser Atherectomy.

    Science.gov (United States)

    Idemoto, Akiko; Okamoto, Naotaka; Tanaka, Akihiro; Mori, Naoki; Nakamura, Daisuke; Yano, Masamichi; Makino, Nobuhiko; Egami, Yasuyuki; Shutta, Ryu; Tanouchi, Jun; Nishino, Masami

    2017-07-01

    In-stent restenosis (ISR) is a prevalent problem following stenting of femoropopliteal lesions. A potential novel treatment modality for ISR including excimer laser atherectomy (ELA) has become available. We performed ELA for in-stent chronic total occlusion (CTO) of femoropopliteal lesions and evaluated lesion morphology before and after ELA by angioscopy in 2 patients. The angioscopic findings clearly showed removal of in-stent thrombi after ELA. Thus, ELA may be effective for in-stent CTO of femoropopliteal lesions. This is the first report describing the direct visualization of ELA effect for vaporization of thrombi in femoropopliteal in-stent lesions by angioscopy.

  4. Photo-triggering and secondary electron produced ionization in electric discharge ArF* excimer lasers

    Science.gov (United States)

    Xiong, Zhongmin; Kushner, Mark J.

    2011-10-01

    Electric discharge excimer lasers are sustained in multi-atmosphere attaching gas mixtures that are typically preionized to enable a reproducible, uniform glow, which maximizes optical quality and gain. This preionization is often accomplished using UV light produced by a corona discharge within the plasma cavity. To quantify the relationship between corona discharge properties and those of the laser discharge, the triggering of electron avalanche by preionizing UV light in an electric discharge-pumped ArF* excimer laser was numerically investigated using a two-dimensional model. The preionizing UV fluxes were generated by a corona-bar discharge driven by the same voltage pulse as the main discharge sustained in a multi-atmospheric Ne/Ar/Xe/F2 gas mixture. The resulting peak photo-electron density in the inter-electrode spacing is around 108 cm-3, and its distribution is biased toward the UV source. The preionization density increases with increasing dielectric constant and capacitance of the corona bar. The symmetry and uniformity of the discharge are, however, improved significantly once the main avalanche develops. In addition to bulk electron impact ionization, the ionization generated by sheath accelerated secondary electrons was found to be important in sustaining the discharge current at experimentally observed values. At peak current, the magnitude of the ionization by sheath accelerated electrons is comparable to that from bulk electron impact in the vicinity of the cathode.

  5. Agglomeration of amorphous silicon film with high energy density excimer laser irradiation

    International Nuclear Information System (INIS)

    He Ming; Ishihara, Ryoichi; Metselaar, Wim; Beenakker, Kees

    2007-01-01

    In this paper, agglomeration phenomena of amorphous Si (α-Si) films due to high energy density excimer laser irradiation are systematically investigated. The agglomeration, which creates holes or breaks the continuous Si film up into spherical beads, is a type of serious damage. Therefore, it determines an upper energy limit for excimer laser crystallization. It is speculated that the agglomeration is caused by the boiling of molten Si. During this process, outbursts of heterogeneously nucleated vapor bubbles are promoted by the poor wetting property of molten silicon on the SiO 2 layer underneath. The onset of the agglomeration is defined by extrapolating the hole density as a function of the energy density of the laser pulse. A SiO 2 capping layer (CL) is introduced on top of the α-Si film to investigate its influence on the agglomeration. It is found that effects of the CL depend on its thickness. The CL with a thickness less than 300 nm can be used to suppress the agglomeration. A thin CL acts as a confining layer and puts a constraint on bubble burst, and hence suppresses the agglomeration

  6. The European answer to the integration issues of excimer laser annealing in MOS technology

    International Nuclear Information System (INIS)

    Privitera, V.; La Magna, A.; Fortunato, G.; Camalleri, M.; Magri, A.; Simon, F.; Svensson, B.G.

    2004-01-01

    Excimer laser annealing (ELA) of MOSFET devices is currently studied and evaluated within the frame of the IST project 'Fundamentals and applications of laser processing for highly innovative MOS technology' (FLASH), funded by the European Commission. This European consortium aim to demonstrate that ELA can be industrialized in the context of semiconductor device fabrication. The technical achievement of homogeneous irradiation of entire wafers by industrial line beam system set up has been combined with device design solutions, in order to avoid the detrimental effects of the laser beam on device structures and tackle the integration issues, main obstacles for the use of ELA in the semiconductor industry. The launch of ELA, to open a new market segment in the semiconductor industry, implies also the availability of reliable process simulation tools. Therefore, a simulation program based on the phase-field method was produced, fully working and available

  7. Effect of laser-plasma X-ray irradiation on crystallization of amorphous silicon film by excimer laser annealing

    International Nuclear Information System (INIS)

    Matsuo, Naoto; Uejukkoku, Kazuya; Heya, Akira; Takanashi, Yasuyuki; Amano, Sho; Miyamoto, Shuji; Mochizuki, Takayasu

    2007-01-01

    The effect of laser plasma soft X-ray (LPX) irradiation on crystallization by excimer laser annealing (ELA) was investigated at low ELA energy densities. The crystalline fraction at energy densities of 50 and 60 mJ/cm 2 for LPX followed by ELA is nearly equal to that at 80 to 100 mJ/cm 2 for the ELA method with non-LPX irradiation. The results obtained indicate that LPX irradiation before ELA reduces the critical energy density for the start of crystallization. The combined method of LPX irradiation and ELA will enable us to realize a low-temperature process for ELA crystallization. (author)

  8. Micro flow-through PCR in a PMMA chip fabricated by KrF excimer laser.

    Science.gov (United States)

    Yao, Liying; Liu, Baoan; Chen, Tao; Liu, Shibing; Zuo, Tiechuan

    2005-09-01

    As the third PCR technology, micro flow-through PCR chip can amplify DNA specifically in an exponential fashion in vitro. Nowadays many academies in the world have successfully amplified DNA using their own-made flow-through PCR chip. In this paper, the ablation principle of PMMA at 248 nm excimer laser was studied, then a PMMA based flow-through PCR chip with 20 cycles was fabricated by excimer laser at 19 kv and 18 mm/min. The chip was bonded together with another cover chip at 105( composite function)C, 160 N and 20 minutes. In the end, it was integrated with electrical thermal thin films and Pt 100 temperature sensors. The temperature controllers was built standard PID digital temperature controller, the temperature control precision was +/- 0.2( composite function)C. The temperature grads between the three temperature zones were 16.5 and 22.2( composite function)C respectively, the gaps between the temperature zones could realize heat insulation.

  9. The Improvement of Electrical Characteristics of Pt/Ti Ohmic Contacts to Ga-Doped ZnO by Homogenized KrF Pulsed Excimer Laser Treatment

    Science.gov (United States)

    Oh, Min-Suk

    2018-04-01

    We investigated the effect of KrF excimer laser surface treatment on Pt/Ti ohmic contacts to Ga-doped n-ZnO ( N d = 4.3 × 1017 cm-3). The treatment of the n-ZnO surfaces by laser irradiation greatly improved the electrical characteristics of the metal contacts. The Pt/Ti ohmic layer on the laser-irradiated n-ZnO showed specific contact resistances of 2.5 × 10-4 ˜ 4.8 × 10-4 Ω cm2 depending on the laser energy density and gas ambient, which were about two orders of magnitude lower than that of the as-grown sample, 8.4 × 10-2 Ω cm2. X-ray photoelectron spectroscopy and photoluminescence measurements showed that the KrF excimer laser treatments increased the electron concentration near the surface region of the Ga-doped n-ZnO due to the preferential evaporation of oxygen atoms from the ZnO surface by the laser-induced dissociation of Zn-O bonds.

  10. Visual and refractive outcomes following myopic laser-assisted subepithelial keratectomy with a flying-spot excimer laser.

    Science.gov (United States)

    McAlinden, Colm; Skiadaresi, Eirini; Moore, Jonathan E

    2011-05-01

    To investigate the visual and refractive outcomes following laser-assisted subepithelial keratectomy (LASEK) surgery with a flying-spot excimer laser. Private practice, Ireland. Case series. In this prospective study, the mean manifest spherical equivalent (SE), sphere, and cylinder were measured preoperatively. All eyes had LASEK surgery with an aberration-free algorithm with the Schwind Amaris excimer laser. Outcomes measured at 1 month, 6 months, and 1 year were uncorrected distance visual acuity (UDVA), manifest refraction, corrected distance visual acuity, contrast sensitivity, aberrometry, and complications. Accuracy, efficacy, and safety were evaluated at 1 year. Preoperatively, the mean SE, sphere, and cylinder in the 80 eyes (48 patients) were -3.58 diopters (D) ± 2.00 (SD), -3.23 ± 1.93 D, and -0.85 ± 0.65 D, respectively. One year postoperatively, the mean SE was -0.00 ± 0.22 D; 57 eyes (71%) were within -0.13 to +0.13 D of the SE, and 71 eyes (98%) were within ±0.50 D. The mean UDVA was -0.06 ± 0.07 logMAR, with an efficacy index of 1.04. The postoperative SE was stable between 1 month, 3 months, and 1 year. One eye (1%) had a change in SE by more than 0.50 D at 6 months and 1 year. There were no statistically significant differences in any aberrations at 1 year. The contrast sensitivity improved from 1.66 ± 0.17 log units preoperatively to 1.72 ± 0.15 log units at 1 month postoperatively (P=.0003), which was unchanged at 6 months and 1 year. This study demonstrated the effectiveness of LASEK for the treatment of myopia with this flying-spot excimer laser. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  11. Structuring of poly ether ether ketone by ArF excimer laser radiation in different atmospheres

    International Nuclear Information System (INIS)

    Feng, Y.; Gottmann, J.; Kreutz, E.W.

    2003-01-01

    Structuring of poly ether ether ketone (PEEK) by 193 nm ArF excimer laser radiation has been investigated. Experiments were carried out in different atmospheres (air, vacuum, Ar, O 2 ) in order to study its influence on the quality of the structures and the formation of the debris. Repetition rate makes little effect on the ablation rate and roughness of the structure in presence of any kind of atmosphere, indicating for the structuring of PEEK by ArF laser radiation a large window of processing. The roughness at the bottom of the structures and the morphology of the side walls are strongly affected by the properties of the atmosphere. The smallest roughness is achieved at 0.6 J/cm 2 for all kinds of processing gases. Debris around the structures can be diminished by structuring in vacuum. Plasma expansion speed has been measured by using high speed photography

  12. Gasochromic performance of WO3-nanorod thin films fabricated with an ArF excimer laser

    International Nuclear Information System (INIS)

    Yaacob, M. H.; Ou, J. Z.; Wlodarski, W.; Kim, C. S.; Lee, J. Y.; Kim, Y. H.; Oh, C. M.; Dhakal, K. P.; Kim, J. Y.; Kang, J. H.

    2012-01-01

    Thin films with tungsten trioxide (WO 3 ) nanorods were fabricated by using an ArF pulsed laser deposition system. Because the ArF excimer laser operates at a very short wavelength of 193 nm, short enough to expect strong absorption of the photons in the semiconductor oxide targets, and because the clusters incoming to the substrates have high momentum, we could build thin films with good surface morphology. Highly homogeneous arrays of nanorods with sizes mostly in the range of 30 - 40 nm were observed. The absorbance response towards hydrogen (H 2 ) gas was investigated for a WO 3 film coated with 25-A-thick palladium (Pd). The Pd/WO 3 -nanorod thin films exhibited excellent gasochromic response when measured in the visible-NIR range (400 - 1000 nm). As low as 0.06% H 2 concentration was clearly sensed. A significant reversible absorbance change and fast recovery ( 2 at different concentrations.

  13. In-vitro ablation of fibrocartilage by XeCl excimer laser

    Science.gov (United States)

    Buchelt, Martin; Papaioannou, Thanassis; Fishbein, Michael C.; Peters, Werner; Beeder, Clain; Grundfest, Warren S.

    1991-07-01

    A 308 nm excimer laser was employed for ablation of human fibrocartilage. Experiments were conducted in vitro. The tissue response was investigated with respect to dosimetry (ablation rate versus radiant exposure) and thermal effect (thermographic analysis). Irradiation was performed via a 600 um fiber, with radiant exposures ranging between 20mj/mm2 and 80mj/mm2, at 20Hz. The ablation rates were found to range from 3um/pulse to 80um/pulse depending on the radiant exposure and/or the applied pressure on the delivery system. Thermographic analysis, during ablation, revealed maximum average temperatures of about 65 degree(s)C. Similar measurements performed, for the purpose of comparison, with a CW Nd:YAG and a CW CO2 laser showed higher values, of the order of 200 degree(s)C.

  14. Measurements of barium photocathode quantum yields at four excimer laser wavelengths

    International Nuclear Information System (INIS)

    Van Loy, M.D.; Young, A.T.; Leung, K.N.

    1992-06-01

    The electron quantum yields from barium cathodes excited by excimer laser radiation at 193, 248, 308, and 351 nm have been determined. Experiments with different cathode surface preparation techniques reveal that deposition of barium film a few microns thick on a clean copper surface under moderate vacuum conditions achieves relatively high quantum efficiencies. Quantum yields measured from surfaces prepared in this manner are 2.3 x 10 -3 at 193 nm, 7.6 x 10 - 4 at 248 nm, 6.1 x 10 -4 at 308 nm, and 4.0 x 10 -4 at 351 nm. Other preparation techniques, such as laser cleaning of a solid barium surface, produced quantum yields that were at least an order of magnitude lower than these values

  15. Boron distribution in silicon after excimer laser annealing with multiple pulses

    International Nuclear Information System (INIS)

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Italia, M.; Privitera, V.; Fortunato, G.; Cuscuna, M.; Mariucci, L.

    2005-01-01

    We have studied B re-distribution in Si after excimer laser annealing (ELA) with multiple laser pulses. B was implanted using both B and BF 2 ions with energies from 1 to 20 keV and doses of 1 x 10 14 and 1 x 10 15 cm -2 . ELA with the number of pulses from 1 to 100 was performed in vacuum with the sample kept at room temperature and 450 deg. C. Independently of the implantation parameters and the ELA conditions used, a peak in the B concentration is observed near the maximum melting depth after 10 pulses of ELA. A detailed study has revealed that B accumulates at the maximum melt depth gradually with the number of ELA pulses. An increase in the carrier concentration at the maximum melt depth is observed after ELA with 100 pulses. No structural defects have been detected by transmission electron microscopy in the region of the B accumulation

  16. Time-resolved spectroscopy and fluorescence resonance energy transfer in the study of excimer laser damage of chromatin

    Energy Technology Data Exchange (ETDEWEB)

    Radu, L. [Department of Molecular Genetics and Radiobiology, Babes National Institute, Bucharest (Romania)], E-mail: lilianajradu@yahoo.fr; Mihailescu, I. [Department of Lasers, Laser, Plasma and Radiation Physics Institute, Bucharest (Romania); Radu, S. [Department of Computer Science, Polytechnics University, Bucharest (Romania); Gazdaru, D. [Department of Biophysics, Bucharest University (Romania)

    2007-09-21

    The analysis of chromatin damage produced by a 248 nm excimer laser radiation, for doses of 0.3-3 MJ/m{sup 2} was carried out by time-resolved spectroscopy and fluorescence resonance energy transfer (FRET). The chromatin was extracted from a normal and a tumoral tissue of Wistar rats. The decrease with laser dose of the relative contribution of the excited state lifetimes of ethidium bromide (EtBr) bounded to chromatin constitutes an evidence of the reduction of chromatin deoxyribonucleic acid (DNA) double-strand structure. FRET was performed from dansyl chloride to acridine orange, both coupled to chromatin. The increase of the average distance between these ligands, under the action of laser radiation, reflects a loosening of the chromatin structure. The radiosensitivity of tumor tissue chromatin is higher than that of a normal tissue. The determination of the chromatin structure modification in an excimer laser field can be of interest in laser therapy.

  17. Time-resolved spectroscopy and fluorescence resonance energy transfer in the study of excimer laser damage of chromatin

    International Nuclear Information System (INIS)

    Radu, L.; Mihailescu, I.; Radu, S.; Gazdaru, D.

    2007-01-01

    The analysis of chromatin damage produced by a 248 nm excimer laser radiation, for doses of 0.3-3 MJ/m 2 was carried out by time-resolved spectroscopy and fluorescence resonance energy transfer (FRET). The chromatin was extracted from a normal and a tumoral tissue of Wistar rats. The decrease with laser dose of the relative contribution of the excited state lifetimes of ethidium bromide (EtBr) bounded to chromatin constitutes an evidence of the reduction of chromatin deoxyribonucleic acid (DNA) double-strand structure. FRET was performed from dansyl chloride to acridine orange, both coupled to chromatin. The increase of the average distance between these ligands, under the action of laser radiation, reflects a loosening of the chromatin structure. The radiosensitivity of tumor tissue chromatin is higher than that of a normal tissue. The determination of the chromatin structure modification in an excimer laser field can be of interest in laser therapy

  18. Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

    International Nuclear Information System (INIS)

    Kurogi, H.; Yamagata, Y.; Ebihara, K.

    1998-01-01

    Pb(Zr X Ti 1-X )O 3 (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, λ=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm -2 on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be P r =15 μC cm -2 , 30 μC cm -2 and E c =200 kV cm -1 , 100 kV cm -1 for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 10 8 cycles of switching. (orig.)

  19. Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

    Energy Technology Data Exchange (ETDEWEB)

    Kurogi, H; Yamagata, Y; Ebihara, K [Kumamoto Univ. (Japan). Dept. of Electr. Eng. and Comput. Sci.; Inoue, N [Kyushu Electric Power Co., Inc., Suizenji, 1-6-36, Kumamoto 862 (Japan)

    1998-03-01

    Pb(Zr{sub X}Ti{sub 1-X})O{sub 3} (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, {lambda}=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm{sup -2} on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be P{sub r}=15 {mu}C cm{sup -2}, 30 {mu}C cm{sup -2} and E{sub c}=200 kV cm{sup -1}, 100 kV cm{sup -1} for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 10{sup 8} cycles of switching. (orig.) 7 refs.

  20. Evaluation and diffusion of excimer laser treatment of myopia in the United States and in the Netherlands

    NARCIS (Netherlands)

    Vondeling, H.; Rosendal, H.; Banta, D.

    1995-01-01

    Excimer laser photorefractive keratectomy (PRK) is an experimental treatment to correct myopia (short-sightedness) that is diffusing into use without convincing evidence of safety and efficacy. It has been claimed that PRK may render conventional methods of correcting myopia, such as wearing glasses

  1. Excimer laser processing of ZnO thin films prepared by the sol-gel process

    International Nuclear Information System (INIS)

    Winfield, R.J.; Koh, L.H.K.; O'Brien, Shane; Crean, Gabriel M.

    2007-01-01

    ZnO thin films were prepared on soda-lime glass from a single spin-coating deposition of a sol-gel prepared with anhydrous zinc acetate [Zn(C 2 H 3 O 2 ) 2 ], monoethanolamine [H 2 NC 2 H 4 OH] and isopropanol. The deposited films were dried at 50 and 300 deg. C. X-ray analysis showed that the films were amorphous. Laser annealing was performed using an excimer laser. The laser pulse repetition rate was 25 Hz with a pulse energy of 5.9 mJ, giving a fluence of 225 mJ cm -2 on the ZnO film. Typically, five laser pulses per unit area of the film were used. After laser processing, the hexagonal wurtzite phase of zinc oxide was observed from X-ray diffraction pattern analysis. The thin films had a transparency of greater than 70% in the visible region. The optical band-gap energy was 3.454 eV. Scanning electron microscopy and profilometry analysis highlighted the change in morphology that occurred as a result of laser processing. This comparative study shows that our sol-gel processing route differs significantly from ZnO sol-gel films prepared by conventional furnace annealing which requires temperatures above 450 deg. C for the formation of crystalline ZnO

  2. Improvement of physical properties of IGZO thin films prepared by excimer laser annealing of sol–gel derived precursor films

    International Nuclear Information System (INIS)

    Tsay, Chien-Yie; Huang, Tzu-Teng

    2013-01-01

    Indium gallium zinc oxide (IGZO) transparent semiconductor thin films were prepared by KrF excimer laser annealing of sol–gel derived precursor films. Each as-coated film was dried at 150 °C in air and then annealed using excimer laser irradiation. The influence of laser irradiation energy density on surface conditions, optical transmittances, and electrical properties of laser annealed IGZO thin films were investigated, and the physical properties of the excimer laser annealed (ELA) and the thermally annealed (TA) thin films were compared. Experimental results showed that two kinds of surface morphology resulted from excimer laser annealing. Irradiation with a lower energy density (≤250 mJ cm −2 ) produced wavy and irregular surfaces, while irradiation with a higher energy density (≥350 mJ cm −2 ) produced flat and dense surfaces consisting of uniform nano-sized amorphous particles. The explanation for the differences in surface features and film quality is that using laser irradiation energy to form IGZO thin films improves the film density and removes organic constituents. The dried IGZO sol–gel films irradiated with a laser energy density of 350 mJ/cm 2 had the best physical properties of all the ELA IGZO thin films. The mean resistivity of the ELA 350 thin films (4.48 × 10 3 Ω cm) was lower than that of TA thin films (1.39 × 10 4 Ω cm), and the average optical transmittance in the visible range (90.2%) of the ELA 350 thin films was slightly higher than that of TA thin films (89.7%). - Highlights: • IGZO semiconductor films were prepared by laser annealing of sol–gel derived films. • Surface roughness and resistivity of ELA samples were affected by energy density. • The ELA 350 IGZO film exhibited the best properties among all of ELA IGZO films. • Transmittance and resistivity of ELA 350 films are greater than those of TA films

  3. excimer laser

    Indian Academy of Sciences (India)

    This gas then passes through a set of water-cooled aluminum finned tube heat exchangers. ... been made leak tight better than 10. −5 ... The excitation circuit primarily consists of a high voltage power supply, a thyratron (CX 3608). Figure 4.

  4. Analyses of surface coloration on TiO2 film irradiated with excimer laser

    International Nuclear Information System (INIS)

    Zheng, H.Y.; Qian, H.X.; Zhou, W.

    2008-01-01

    TiO 2 film of around 850 nm in thickness was deposited on a soda-lime glass by PVD sputtering and irradiated using one pulse of krypton-fluorine (KrF) excimer laser (wavelength of 248 nm and pulse duration of 25 ns) with varying fluence. The color of the irradiated area became darker with increasing laser fluence. Irradiated surfaces were characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Surface undergoes thermal annealing at low laser fluence of 400 and 590 mJ/cm 2 . Microcracks at medium laser fluence of 1000 mJ/cm 2 are attributed to surface melting and solidification. Hydrodynamic ablation is proposed to explain the formation of micropores and networks at higher laser fluence of 1100 and 1200 mJ/cm 2 . The darkening effect is explained in terms of trapping of light in the surface defects formed rather than anatase to rutile phase transformation as reported by others. Controlled darkening of TiO 2 film might be used for adjustable filters

  5. Optical and electronic properties of HWCVD and PECVD silicon films irradiated using excimer and Nd:Yag lasers

    International Nuclear Information System (INIS)

    Shaikh, M.Z.; O'Neill, K.A.; Anthony, S.; Persheyev, S.K.; Rose, M.J.

    2006-01-01

    Thin silicon film samples were deposited using HWCVD and PECVD techniques to study the influence of laser annealing on their optical and electronic properties. Samples were annealed in air using a XeCl excimer and Nd:Yag lasers. Excimer laser annealing (ELA) at 50 to 222 mJ/cm 2 increased conductivity in PECVD films by 2 to 3 orders of magnitude and in HWCVD films by 1 to 2 orders of magnitude. ELA was also seen to decrease the optical gap in PECVD films by 0.5 eV and HWCVD films by 0.15 eV. Silicon-oxygen bond content was higher in as-deposited HWCVD films than PECVD films. Hydrogen content (at.%) in PECVD films was higher than HWCVD for higher H dilution ratios. A Nd:Yag laser 3-beam interference pattern was used to produce a periodic array of crystals in both PECVD and HWCVD films

  6. Deposition of high Tc superconductor thin films by pulsed excimer laser ablation and their post-synthesis processing

    International Nuclear Information System (INIS)

    Ogale, S.B.

    1992-01-01

    This paper describes the use of pulsed excimer laser ablation technique for deposition of high quality superconductor thin films on different substrate materials such as Y stabilized ZrO 2 , SrTiO 3 , LiNbO 3 , Silicon and Stainless Steels, and dopant incorporation during the film depositions. Processing of deposited films using ion and laser beams for realisation of device features are presented. 28 refs., 16 figs

  7. Surface modification of Al–Si alloy by excimer laser pulse processing

    Energy Technology Data Exchange (ETDEWEB)

    Mahanty, S., E-mail: soumitro@iitk.ac.in; Gouthama

    2016-04-15

    The laser irradiation on Al-Si alloy sample is carried out by excimer laser in ambient conditions for 30 or 45 pulses. Microstructural investigation of laser treated sample is done by OM, SEM and TEM and the surface hardness is evaluated by Vickers micro indentation. Laser treated, samples suggested the dissolution of coarse primary Si and β-AlFeSi particle in α-Al matrix. The SEM/EDS study shows the enhancement of retained Si in α-Al matrix. The interface analysis of laser treated sample suggested the effected modified depth is ∼6 μm. TEM investigation shows the formation of nanocrystalline Si in size ∼2–15 nm. The cellular structures of size range ∼30–50 nm are observed after 45 pulses. The α-Al cells and Si precipitates sizes were considerably refined at higher number of pulses. The fine Si precipitates are found to be dispersed in the intercellular boundaries. An improvement in surface hardness from ∼1.6 to 1.8 is observed 30 and 45 pulse treatment, respectively. The mechanism involves for improvement in surface properties are non-equilibrium solidification, metastable phase formation and microstructural refinement. - Highlights: • Coarse Si and β phase intermetallic are melted and the constituent elements dispersed into the matrix during re-solidification. • The solid solubility of the Si at the surface enhanced after the laser treatment. • The Cellular structure with the size range ∼30–50 nm observed in α-Al after 45 laser pulses. • Si nano particles in size ∼ 2–15 nm were observed in the intercellular region. • Surface hardness increased after laser processing.

  8. Simulation of beam pointing stability on targeting plane of high power excimer laser system

    International Nuclear Information System (INIS)

    Wang Dahui; Zhao Xueqing; Zhang Yongsheng; Zheng Guoxin; Hu Yun; Zhao Jun

    2011-01-01

    Based on characteristics of image-relaying structure in high power excimer MOPA laser system, simulation and analysis software of targeting beam's barycenter stability was designed by using LABVIEW and MATLAB. Simulation was made to measured results of every optical component in laboratory environment. Simulation and validation of budget values for optical components was and optimization of error budget of system was accomplished via post-allocation for several times. It is shown that targeting beam's barycenter stability in the condition of current laboratory environment can't satisfy needs and index of high demand optical components can be allotted to 1.7 μrad when index of low demand optical components have some stability margin. These results can provide a guide to construction of system and design and machining of optical components and optimization of system. Optical components of laboratory on work can satisfy optimized distributed index, which reduce the demand of structure to some extent. (authors)

  9. [Excimer laser therapy of alopecia areata--side-by-side evaluation of a representative area].

    Science.gov (United States)

    Raulin, Christian; Gündogan, Cüneyt; Greve, Bärbel; Gebert, Susanne

    2005-07-01

    We report for the first time on hair regrowth in alopecia areata of the scalp achieved with the 308-nm xenon-chloride excimer laser in a prospective side-by-side trial. The alopecia areata had shown progression over a period of three years, and various treatments had not been effective. Out of a number of affected areas, one representative lesion was chosen; one half of it was treated, the other half remained untreated. After 27 sessions (200 - 4000 mJ/cm2, cumulative dose 52.6 J/cm2) over 3 months, only the treated area showed hair growth; which suggests that this was most probably not a spontaneous remission.

  10. Analysis of excimer laser radiant exposure effect toward corneal ablation volume at LASIK procedure

    Science.gov (United States)

    Adiati, Rima Fitria; Rini Rizki, Artha Bona; Kusumawardhani, Apriani; Setijono, Heru; Rahmadiansah, Andi

    2016-11-01

    LASIK (Laser Asissted In Situ Interlamelar Keratomilieusis) is a technique for correcting refractive disorders of the eye such as myopia and astigmatism using an excimer laser. This procedure use photoablation technique to decompose corneal tissues. Although preferred due to its efficiency, permanency, and accuracy, the inappropriate amount radiant exposure often cause side effects like under-over correction, irregular astigmatism and problems on surrounding tissues. In this study, the radiant exposure effect toward corneal ablation volume has been modelled through several processes. Data collecting results is laser data specifications with 193 nm wavelength, beam diameter of 0.065 - 0.65 cm, and fluence of 160 mJ/cm2. For the medical data, the myopia-astigmatism value, cornea size, corneal ablation thickness, and flap data are taken. The first modelling step is determining the laser diameter between 0.065 - 0.65 cm with 0.45 cm increment. The energy, power, and intensity of laser determined from laser beam area. Number of pulse and total energy is calculated before the radiant exposure of laser is obtained. Next is to determine the parameters influence the ablation volume. Regression method used to create the equation, and then the spot size is substituted to the model. The validation used is statistic correlation method to both experimental data and theory. By the model created, it is expected that any potential complications can be prevented during LASIK procedures. The recommendations can give the users clearer picture to determine the appropriate amount of radiant exposure with the corneal ablation volume necessary.

  11. 308-nm excimer lamp for the treatment of alopecia areata: Clinical trial on 16 cases

    Directory of Open Access Journals (Sweden)

    Akiko Ohtsuki

    2013-01-01

    Full Text Available Background: Alopecia areata (AA is considered as a T-cell mediated autoimmune disorder. The 308-nm excimer laser is thought to be capable of inducing T-cell apoptosis in vitro, suggesting that the 308-nm excimer lamp (not laser might be effective for the treatment of AA. We examined the effectiveness of the 308-nm excimer lamp for treating AA. Materials and Methods: We treated 16 patients with single AA and multiple AA (MAA. The lesions were irradiated with a 308-nm excimer lamp at 2-week intervals. Results: Hair regrowth was observed in 14 patients. Among them, 10 patients showed more than 50% hair re-growth. Our results suggested that the 308-nm excimer lamp system is effective and safe for the treatment of single AA and MAA. Conclusion: Our results suggest that the 308-nm excimer lamp is a good therapeutic alternative without serious side effect for treating AA.

  12. Effects of DC gate and drain bias stresses on the degradation of excimer laser crystallized polysilicon thin film transistors

    International Nuclear Information System (INIS)

    Kouvatsos, D N; Michalas, L; Voutsas, A T; Papaioannou, G J

    2005-01-01

    The effects of gate and drain bias stresses on thin film transistors fabricated in polysilicon films crystallized using the advanced sequential lateral solidification excimer laser annealing (SLS ELA) process, which yields very elongated polysilicon grains and allows the fabrication of TFTs without grain boundary barriers to current flow, are investigated as a function of the active layer thickness and of the TFT orientation relative to the grains. The application of hot carrier stress, with a condition of V GS = V DS /2, was determined to induce threshold voltage, subthreshold swing and transconductance degradation for TFTs in thicker polysilicon films and the associated stress-induced increase in the active layer trap density was evaluated. However, this device degradation was drastically reduced for TFTs fabricated in ultra-thin films. Furthermore, the application of the same stress condition to TFTs oriented vertically to the elongated grains resulted in similar threshold voltage shift but in substantially decreased subthreshold swing and transconductance degradation. The immunity of ultra-thin active layer devices to degradation under hot carrier stress clearly suggests the implementation of ultra thin SLS ELA polysilicon films for the fabrication of TFTs exhibiting not only high performance but, especially, the high reliability needed for integrated systems on panel

  13. FEM for modelling 193 nm excimer laser treatment of SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub x} heterostructures on SOI substrates

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C.; Chiussi, S.; Gontad, F.; Gonzalez, P. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas, Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain)

    2011-03-15

    Research on epitaxial crystalline silicon (c-Si) and silicon-germanium (Si{sub 1-x}Ge{sub x}) alloys growth and annealing for microelectronic purposes, such as Micro- or Nano-Electro-Mechanical Systems (MEMS or NEMS) and Silicon-On-Nothing (SON) devices is continuously in progress. Laser assisted annealing techniques using commercial ArF Excimer Laser sources are based on ultra-rapid heating and cooling cycles induced by the 193 nm pulses of 20 ns, which are absorbed in the near surface region of the heterostructures. During and after the absorption of these laser pulses, complex physical processes appear that strongly depend on sample structure and applied laser pulse energy densities. The control of the experimental parameters is therefore a key task for obtaining high quality alloys. The Finite ElementsMethod (FEM) is a powerful tool for the optimization of such treatments, because it provides the spatial and temporal temperature fields that are produced by the laser pulses. In this work, we have used a FEM commercial software, to predict the temperatures gradients induced by ArF excimer laser over a wide energy densities range, 0.1<{phi}<0.4 J/cm{sup 2}, on different SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub (x)} thin films deposited on SOI substrate. These numerical results allow us to predict the threshold energies needed to reach the melting point (MP) of the Si and SiGe alloy without oxidation of the thin films system. Therefore, it is possible to optimize the conditions to achieve high quality epitaxy films. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Safety, efficacy, predictability and stability of laser in situ keratomileusis (LASIK) with a 1000-Hz scanning spot excimer laser.

    Science.gov (United States)

    Khoramnia, Ramin; Salgado, Josefina P; Wuellner, Christian; Donitzky, Christof; Lohmann, Chris P; Winkler von Mohrenfels, Christoph

    2012-09-01

    To evaluate the safety, efficacy, predictability and stability of laser in situ keratomileusis (LASIK) with a 1000-Hz scanning spot excimer laser (Concept System 1000; WaveLight GmbH, Erlangen, Germany). LASIK was performed on twenty eyes with myopia or myopic astigmatism (mean spherical equivalent refraction: -3.97±1.72 dioptres (D); mean cylinder: -0.84±0.77 D) using a microkeratome for flap creation and the Concept System 1000 for photoablation. Patients were examined preoperatively as well as 1, 3 and 6 months after the treatment. Manifest sphere and cylinder, uncorrected (UCDVA) and best corrected (BCDVA) distance visual acuity, corneal topography and pachymetry were analysed. We observed no adverse events that might have been associated with the use of a repetition rate of 1000 Hz. All eyes maintained or had improved BCDVA at 6 months after treatment when compared to preoperative values. Six months after LASIK, UCDVA was 20/20 or better in 85% and 20/25 or better in 100% of the eyes. The spherical equivalent refraction was within ±0.50 D in 95% of the eyes at 6 months after surgery. The refraction stayed stable over time; 95% of the eyes changedLASIK with the prototype 1000-Hz excimer laser was safe, efficient and predictable. The postoperative refraction was stable over time. There were no specific clinical side-effects that might be associated with the use of such a high repetition rate. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

  15. Krypton Gas for High Quality Single Wall Carbon Nanotubes Synthesis by KrF Excimer Laser Ablation

    Directory of Open Access Journals (Sweden)

    Jasim Al-Zanganawee

    2015-01-01

    Full Text Available We report for the first time the production of single wall carbon nanotubes (SWCNTs by KrF excimer laser ablation method under the krypton gas atmosphere. For the ablation experiment 450 mJ energy and 30 Hz repetition rate KrF excimer laser was used, and the target was prepared with the following composition: 0.6% Ni, 0.6% Co, and 98.8% C (atomic percentage. The ablation product was characterized by confocal Raman microspectroscopy, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and thermogravimetric analysis (TGA. The SWCNTs obtained are a mixture of semiconducting and metallic types with narrow diameters distribution of 1.26 to 1.49 nm, are micrometers long, and contain low amount of graphite and amorphous carbon.

  16. Outcomes of excimer laser enhancements in pseudophakic patients with multifocal intraocular lens

    Directory of Open Access Journals (Sweden)

    Schallhorn SC

    2016-04-01

    Full Text Available Steven C Schallhorn,1–3 Jan A Venter,2 David Teenan,2 Julie M Schallhorn,3 Keith A Hettinger,2 Stephen J Hannan,2 Martina Pelouskova2 1Department of Ophthalmology, University of California, San Francisco, CA, USA; 2Optical Express, Glasgow, UK; 3Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA Purpose: The aim of this study was to assess visual and refractive outcomes of laser vision correction (LVC to correct residual refraction after multifocal intraocular lens (IOL implantation. Patients and methods: In this retrospective study, 782 eyes that underwent LVC to correct unintended ametropia after multifocal IOL implantation were evaluated. Of all multifocal lenses implanted during primary procedure, 98.7% were refractive and 1.3% had a diffractive design. All eyes were treated with VISX STAR S4 IR excimer laser using a convectional ablation profile. Refractive outcomes, visual acuities, patient satisfaction, and quality of life were evaluated at the last available visit. Results: The mean time between enhancement and last visit was 6.3±4.4 months. Manifest spherical equivalent changed from -0.02±0.83 D (-3.38 D to +2.25 D pre-enhancement to 0.00±0.34 D (-1.38 D to +1.25 D post-enhancement. At the last follow-up, the percentage of eyes within 0.50 D and 1.00 D of emmetropia was 90.4% and 99.5%, respectively. Of all eyes, 74.9% achieved monocular uncorrected distance visual acuity 20/20 or better. The mean corrected distance visual acuity remained the same before (-0.04±0.06 logMAR [logarithm of the minimum angle of resolution] and after LVC procedure (-0.04±0.07 logMAR; P=0.70. There was a slight improvement in visual phenomena (starburst, halo, glare, ghosting/double vision following the enhancement. No sight-threatening complications related to LVC occurred in this study. Conclusion: LVC in pseudophakic patients with multifocal IOL was safe, effective, and predictable in a large cohort of

  17. Topography-guided treatment of irregular astigmatism with the wavelight excimer laser.

    Science.gov (United States)

    Jankov, Mirko R; Panagopoulou, Sophia I; Tsiklis, Nikolaos S; Hajitanasis, Georgos C; Aslanides, loannis M; Pallikaris, loannis G

    2006-04-01

    To evaluate the feasibility, safety, and predictability of correcting high irregular astigmatism in symptomatic eyes with the use of topography-guided photoablation. In a prospective, non-comparative case series, 16 consecutive symptomatic eyes of 11 patients with small hyperopic and myopic excimer laser optical zones, decentered and irregular ablation after corneal graft, and corneal scars were operated. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest and cycloplegic refraction, and corneal topography, with asphericity and regularity, were analyzed. LASIK (n = 10) and photorefractive keratectomy (n = 6) were performed using the ALLEGRETTO WAVE excimer laser and T-CAT software (Topography-guided Customized Ablation Treatment; WaveLight Laser Technologie AG, Erlangen, Germany). In the LASIK group, UCVA improved from 0.81 +/- 0.68 IogMAR (20/130) (range: 0.2 to 2.0) to 0.29 +/- 0.21 logMAR (20/39) (range: 0.1 to 0.7) at 6 months. In the PRK group, mean UCVA improved from 0.89 +/- 0.87 IogMAR (20/157) (range: 0.1 to 2.0) to 0.42 +/- 0.35 logMAR (20/53) (range: 0.1 to 1.0) at 6 months. Best spectacle-corrected visual acuity did not change significantly in either group. One PRK patient lost one line of BSCVA. Refractive cylinder for the LASIK group improved from -2.53 +/- 1.71 diopters (D) (range: -0.75 to -5.75 D) to -1.28 +/- 0.99 D (range: 0 to -2.50 D) at 6 months. Refractive cylinder in the PRK group improved from -2.21 +/- 2.11 D (range: -0.25 to -5.50 D) to -1.10 +/- 0.42 D (range: -0.50 to -1.50 D). Index of surface irregularity showed a decrease from 60 +/- 12 (range: 46 to 89) to 50 +/- 9 (range: 32 to 63) at 6 months in the LASIK group whereas no significant change was noted in the PRK group. Subjective symptoms, such as glare, halos, ghost images, starbursts, and monocular diplopia, were not present postoperatively. Topography-guided LASIK and PRK resulted in a significant reduction of refractive cylinder and

  18. Excimer laser doping technique for application in an integrated CdTe imaging device

    CERN Document Server

    Mochizuki, D; Aoki, T; Tomita, Y; Nihashi, T; Hatanaka, Y

    1999-01-01

    CdTe is an attractive semiconductor material for applications in solid-state high-energy X-ray and gamma-ray imaging systems because of its high absorption coefficient, large band gap, good mobility lifetime product of holes and stability at normal atmospheric conditions. We propose a new concept for fabricating an integrated CdTe with monolithic circuit configuration for two-dimensional imaging systems suitable for medical, research or industrial applications and operation at room temperature. A new doping technique has been recently developed that employs excimer laser radiation to diffuse impurity atoms into the semiconductor. Accordingly, heavily doped n- and p-type layers with resistivities less than 1 OMEGA cm can be formed on the high resistive CdTe crystals. We have further extended this technique for doping with spatial pattern. We will present the laser doping technique and various results thus obtained. Spatially patterned doping is demonstrated and we propose the use of these doping techniques for...

  19. Excimer laser assisted very fast exfoliation and reduction of graphite oxide at room temperature under air ambient for Supercapacitors electrode

    Science.gov (United States)

    Malek Hosseini, S. M. B.; Baizaee, S. M.; Naderi, Hamid Reza; Dare Kordi, Ali

    2018-01-01

    Excimer laser was used for reduction and exfoliation of graphite oxide (GO) at room temperature under air ambient. The prepared excimer laser reduced graphite oxide (XLRGO) is characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), nitrogen adsorption/desorption (BET method), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and UV-vis absorption techniques for surface, structural functional groups and band gap analysis. Electrochemical properties are investigated using cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy (EIS) and continues cyclic voltammetry (CCV) in 0.5 M Na2SO4 as electrolyte. Electrochemical investigations revealed that XLRGO electrode has enhanced supercapacitive performance including specific capacitance of 299 F/g at a scan rate of 2 mV/s. Furthermore, CCV measurement showed that XLRGO electrode kept 97.8% of its initial capacitance/capacity after 4000 cycles. The obtained results from electrochemical investigations confirm that the reduction of GO by using an excimer laser produces high-quality graphene for supercapacitor applications without the need for additional operations.

  20. Improvement of physical properties of IGZO thin films prepared by excimer laser annealing of sol–gel derived precursor films

    Energy Technology Data Exchange (ETDEWEB)

    Tsay, Chien-Yie, E-mail: cytsay@fcu.edu.tw; Huang, Tzu-Teng

    2013-06-15

    Indium gallium zinc oxide (IGZO) transparent semiconductor thin films were prepared by KrF excimer laser annealing of sol–gel derived precursor films. Each as-coated film was dried at 150 °C in air and then annealed using excimer laser irradiation. The influence of laser irradiation energy density on surface conditions, optical transmittances, and electrical properties of laser annealed IGZO thin films were investigated, and the physical properties of the excimer laser annealed (ELA) and the thermally annealed (TA) thin films were compared. Experimental results showed that two kinds of surface morphology resulted from excimer laser annealing. Irradiation with a lower energy density (≤250 mJ cm{sup −2}) produced wavy and irregular surfaces, while irradiation with a higher energy density (≥350 mJ cm{sup −2}) produced flat and dense surfaces consisting of uniform nano-sized amorphous particles. The explanation for the differences in surface features and film quality is that using laser irradiation energy to form IGZO thin films improves the film density and removes organic constituents. The dried IGZO sol–gel films irradiated with a laser energy density of 350 mJ/cm{sup 2} had the best physical properties of all the ELA IGZO thin films. The mean resistivity of the ELA 350 thin films (4.48 × 10{sup 3} Ω cm) was lower than that of TA thin films (1.39 × 10{sup 4} Ω cm), and the average optical transmittance in the visible range (90.2%) of the ELA 350 thin films was slightly higher than that of TA thin films (89.7%). - Highlights: • IGZO semiconductor films were prepared by laser annealing of sol–gel derived films. • Surface roughness and resistivity of ELA samples were affected by energy density. • The ELA 350 IGZO film exhibited the best properties among all of ELA IGZO films. • Transmittance and resistivity of ELA 350 films are greater than those of TA films.

  1. Improvement of Anti-TNF-α Antibody-Induced Palmoplantar Pustular Psoriasis Using a 308-nm Excimer Light

    Directory of Open Access Journals (Sweden)

    Natsuko Iga

    2012-11-01

    Full Text Available Anti-tumor necrosis factor (TNF-α antibody is utilized in the treatment of a variety of chronic inflammatory conditions, including psoriasis. However, it can induce paradoxical development and/or exacerbation of psoriasis in the course of anti-TNF-α antibody treatment, which is sometimes refractory to conventional treatments. Herein, we report a case of refractory palmoplantar pustular psoriasis induced by anti-TNF-α antibody treatment, which was improved by treatment with a 308-nm excimer light. The 308-nm excimer light has less long-term risks than narrow-band UVB. The 308-nm excimer light may be a good therapeutic option for refractory psoriatic skin lesions induced by anti-TNF-α antibody therapy because of localized side effects without systemic problems, short length of treatment and low cumulative dosages of UV light.

  2. Excimer laser phototherapeutic keratectomy in conjunction with mitomycin C in corneal macular and granular dystrophies

    Directory of Open Access Journals (Sweden)

    Erdem Yuksel

    2016-04-01

    Full Text Available ABSTRACT Purpose: To evaluate the visual outcomes, recurrence patterns, safety, and efficacy of excimer laser phototherapeutic keratectomy (PTK in conjunction with mitomycin C (MMC for corneal macular and granular diystrophies. Methods: The patients were divided into two groups. Group 1 included patients with macular corneal dystrophy (MCD that caused superficial corneal plaque opacities, and Group 2 included patients with granular corneal dystrophy (GCD. Patients in both groups were pre-, peri-, and postoperatively evaluated. The groups were compared in terms of uncorrected visual acuity (VA, best spectacle-corrected VA, presence of mild or significant recurrence, and time of recurrence. Results: Eighteen eyes (nine with MCD and nine with GCD of 18 patients (10 men and eight women were included. PTK was performed for each eye that was included in this study. The mean ablation amount was 117.8 ± 24.4 µm and 83.5 ± 45.7 µm in MCD and GCD, respectively, (p=0.18. The postoperative improvement of the mean VA was similar between the two groups before recurrences (p>0.43 and after recurrences (p>0.71. There were no statistically significant differences in the recurrence rate and the recurrence-free period for any recurrence type. Conclusion: PTK was an effective, safe, and minimally invasive procedure for patients with MCD and GCD. PTK in conjunction with MMC was similarly effective for both groups in terms of recurrence and visual outcomes.

  3. Excimer laser phototherapeutic keratectomy in conjunction with mitomycin C in corneal macular and granular dystrophies.

    Science.gov (United States)

    Yuksel, Erdem; Cubuk, Mehmet Ozgur; Eroglu, Hulya Yazıcı; Bilgihan, Kamil

    2016-04-01

    To evaluate the visual outcomes, recurrence patterns, safety, and efficacy of excimer laser phototherapeutic keratectomy (PTK) in conjunction with mitomycin C (MMC) for corneal macular and granular diystrophies. The patients were divided into two groups. Group 1 included patients with macular corneal dystrophy (MCD) that caused superficial corneal plaque opacities, and Group 2 included patients with granular corneal dystrophy (GCD). Patients in both groups were pre-, peri-, and postoperatively evaluated. The groups were compared in terms of uncorrected visual acuity (VA), best spectacle-corrected VA, presence of mild or significant recurrence, and time of recurrence. Eighteen eyes (nine with MCD and nine with GCD) of 18 patients (10 men and eight women) were included. PTK was performed for each eye that was included in this study. The mean ablation amount was 117.8 ± 24.4 µm and 83.5 ± 45.7 µm in MCD and GCD, respectively, (p=0.18). The postoperative improvement of the mean VA was similar between the two groups before recurrences (p>0.43) and after recurrences (p>0.71). There were no statistically significant differences in the recurrence rate and the recurrence-free period for any recurrence type. PTK was an effective, safe, and minimally invasive procedure for patients with MCD and GCD. PTK in conjunction with MMC was similarly effective for both groups in terms of recurrence and visual outcomes.

  4. Insight into excimer laser crystallization exploiting ellipsometry: Effect of silicon film precursor

    Energy Technology Data Exchange (ETDEWEB)

    Losurdo, Maria [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy)], E-mail: maria.losurdo@ba.imip.cnr.it; Giangregorio, Maria M.; Sacchetti, Alberto; Capezzuto, Pio; Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy); Mariucci, Luigi; Fortunato, Guglielmo [IFN-CNR, Via Cineto Romano, 42 - 00156 Rome (Italy)

    2007-07-16

    The optical diagnostic of spectroscopic ellipsometry is shown to be an effective tool to investigate the mechanism of excimer laser crystallization (ELC) of silicon thin films. A detailed spectroscopic ellipsometric investigation of the microstructures of polycrystalline Si films obtained on SiO{sub 2}/Si wafers by ELC of a-Si:H and nc-Si films deposited, respectively, by SiH{sub 4} plasma enhanced chemical vapor deposition (PECVD) and SiF{sub 4}-PECVD is presented. It is shown that ellipsometric spectra of the pseudodielectric function of polysilicon thin films allows to discern the three different ELC regimes of partial melting, super lateral growth and complete melting. Exploiting ellipsometry and atomic force microscopy, it is shown that ELC of nc-Si has very low energy density threshold of 95 mJ/cm{sup 2} for complete melting, and that re-crystallization to large grains of {approx} 2 {mu}m can be achieved by multi-shot irradiation at an energy density as low as 260 mJ/cm{sup 2} when using nc-Si when compared to 340 mJ/cm{sup 2} for the ELC of a-Si films.

  5. Excimer Laser Surgery: Biometrical Iris Eye Recognition with Cyclorotational Control Eye Tracker System.

    Science.gov (United States)

    Pajic, Bojan; Cvejic, Zeljka; Mijatovic, Zoran; Indjin, Dragan; Mueller, Joerg

    2017-05-25

    A prospective comparative study assessing the importance of the intra-operative dynamic rotational tracking-especially in the treatment of astigmatisms in corneal refractive Excimer laser correction-concerning clinical outcomes is presented. The cyclotorsion from upright to supine position was measured using iris image comparison. The Group 1 of patients was additionally treated with cyclorotational control and Group 2 only with X-Y control. Significant differences were observed between the groups regarding the mean postoperative cylinder refraction ( p < 0.05). The mean cyclotorsion can be calculated to 3.75° with a standard deviation of 3.1°. The total range of torsion was from -14.9° to +12.6°. Re-treatment rate was 2.2% in Group 1 and 8.2% in Group 2, which is highly significant ( p < 0.01). The investigation confirms that the dynamic rotational tracking system used for LASIK results in highly predictable refraction quality with significantly less postoperative re-treatments.

  6. Post-growth annealing of germanium-tin alloys using pulsed excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lanxiang; Wang, Wei; Zhou, Qian; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117582 (Singapore); Pan, Jisheng; Zhang, Zheng [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2015-07-14

    We investigate the impact of pulsed excimer laser anneal on fully strained germanium-tin alloys (Ge{sub 1−x}Sn{sub x}) epitaxially grown on Ge substrate by molecular beam epitaxy. Using atomic force microscopy, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, the morphological and compositional evolution of Ge{sub 1−x}Sn{sub x} with Sn content up to 17% after annealing using various conditions is studied. Ge{sub 0.83}Sn{sub 0.17} samples annealed at 80 mJ/cm{sup 2} or 150 mJ/cm{sup 2} have no observable changes with respect to the as-grown sample. However, Ge{sub 0.83}Sn{sub 0.17} samples annealed at 250 mJ/cm{sup 2} or 300 mJ/cm{sup 2} have Sn-rich islands on the surface, which is due to Sn segregation in the compressively strained epitaxial film. For Ge{sub 0.89}Sn{sub 0.11}, significant Sn redistribution occurs only when annealed at 300 mJ/cm{sup 2}, indicating that it has better thermal stability than Ge{sub 0.83}Sn{sub 0.17}. A mechanism is proposed to explain the formation of Sn-rich islands and Sn-depleted regions.

  7. Excimer Laser Phototherapeutic Keratectomy for the Treatment of Clinically Presumed Fungal Keratitis

    Directory of Open Access Journals (Sweden)

    Liang-Mao Li

    2014-01-01

    Full Text Available This retrospective study was to evaluate treatment outcomes of excimer laser phototherapeutic keratectomy (PTK for clinically presumed fungal keratitis. Forty-seven eyes of 47 consecutive patients underwent manual superficial debridement and PTK. All corneal lesions were located in the anterior stroma and were resistant to medication therapy for at least one week. Data were collected by a retrospective chart review with at least six months of follow-up data available. After PTK, infected corneal lesions were completely removed and the clinical symptoms resolved in 41 cases (87.2%. The mean ablation depth was 114.39±45.51 μm and diameter of ablation was 4.06±1.07 mm. The mean time for healing of the epithelial defect was 8.8±5.6 days. Thirty-four eyes (82.9% showed an improvement in best spectacle-corrected visual acuity of two or more lines. PTK complications included mild to moderate corneal haze, hyperopic shift, irregular astigmatism, and thinning cornea. Six eyes (12.8% still showed progressed infection, and conjunctival flap covering, amniotic membrane transplantation, or penetrating keratoplasty were given. PTK is a valuable therapeutic alternative for superficial infectious keratitis. It can effectively eradicate lesions, hasten reepithelialization, and restore and preserve useful visual function. However, the selection of surgery candidates should be conducted carefully.

  8. Properties of the ablation process for excimer laser ablation of Y1Ba2Cu3O7

    International Nuclear Information System (INIS)

    Neifeld, R.A.; Potenziani, E.; Sinclair, W.R.; Hill III, W.T.; Turner, B.; Pinkas, A.

    1991-01-01

    The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm 2 . Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm 2 . Several of the parameters measured vary rapidly in the 1--5 J/cm 2 range. Variation in these parameters strongly influences the properties of films grown by this technique

  9. Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

    CERN Document Server

    Gentile, C A; Hartfield, J W; Hawryluk, R J; Hegeler, F; Heitzenroeder, P J; Jun, C H; Ku, L P; Lamarche, P H; Myers, M C; Parker, J J; Parsells, R F; Payen, M; Raftopoulos, S; Sethian, J D

    2002-01-01

    The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, , and ) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W centre dot cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated w...

  10. Influence of laser fluence in ArF-excimer laser assisted crystallisation of a-SiGe:H films

    International Nuclear Information System (INIS)

    Chiussi, S.; Lopez, E.; Serra, J.; Gonzalez, P.; Serra, C.; Leon, B.; Fabbri, F.; Fornarini, L.; Martelli, S.

    2003-01-01

    Polycrystalline silicon germanium (poly-SiGe) coatings are drawing increasing attention as active layers in solar cells, bolometers and various microelectronic devices. As a consequence, alternative low-cost production techniques, capable to produce such alloys with uniform and controlled grain size, become more and more attractive. Excimer laser assisted crystallisation, already assessed in thin film transistor production, has proved to be a valuable 'low-thermal budget' technique for the crystallisation of amorphous silicon. Main advantages are the high process quality and reproducibility as well as the possibility of tailoring the grain size in both, small selected regions and large areas. The feasibility of this technique for producing poly-SiGe films has been studied irradiating hydrogenated amorphous SiGe films with spatially uniform ArF-laser pulses of different fluences. Surface morphology, structure and chemical composition have been extensively characterised, demonstrating the need of using a 'step-by-step' process and a careful adjustment of both, total number of shots and laser fluence at each 'step' in order to diminish segregation effects and severe damages of the film surface and of segregation effects

  11. Clinical results of excimer laser photorefractive keratectomy: a multicenter study of 265 eyes.

    Science.gov (United States)

    Aron-Rosa, D S; Colin, J; Aron, B; Burin, N; Cochener, B; Febraro, J L; Gallinaro, C; Ganem, S; Valdes, R

    1995-11-01

    Efficacy, predictability, and safety of excimer laser photorefractive keratectomy were evaluated at centers in Paris and Brest, France. Photoablation was performed with the VISX laser on 265 eyes (151 at the Paris center and 114 at the Brest center). The eyes were clinically and statistically evaluated over a six month follow-up. Initial myopia ranged from -0.7 to -19.4 diopters (D) (mean spherical equivalent [SE] -5.9 D) in the Paris center and from -0.9 to -14.5 D (SE -4.5 D) in the Brest center. At both centers, the mean uncorrected visual acuity was worse than 20/200; over 90% of cases in each center had a best uncorrected visual acuity of 20/100 or worse. Results are reported globally and for subgroups of myopia: Group A, SE better than or equal to -3.0 D; Group B, SE worse than -3.0 D and better than or equal to -7.0 D; Group C, SE worse than -7.0 D. Uncorrected visual acuity was significantly improved in the patients followed for six months; 64% of Paris cases and 62% of Brest cases obtained an uncorrected visual acuity of 20/40 or better. Predictability of the treatment was good; 67% of Paris eyes and 74% of Brest eyes were less than 1.0 D from the intended correction after six months. The data suggest that the initial myopia affected the efficacy and predictability of the treatment; results in the mild to moderate myopia eyes were significantly better than results in the severe myopia eyes. One case of visual acuity regression (less than one line) was observed in the two groups. This was associated with corneal haze of moderate intensity.

  12. Effectiveness of 308-nm Excimer Laser Therapy in Treating Alopecia Areata, Determined by Examining the Treated Sides of Selected Alopecic Patches.

    Science.gov (United States)

    Byun, Ji Won; Moon, Jong Hyuk; Bang, Chan Yl; Shin, Jeonghyun; Choi, Gwang Seong

    2015-01-01

    Some studies have reported the use of 308-nm excimer laser therapy for treating alopecia areata (AA); however, the effectiveness of this therapy on a theoretical basis has not yet been comparatively analyzed. To determine the therapeutic effect of excimer laser therapy on AA. One alopecic patch was divided into control and treated sides in 10 patients with AA. Then, 308-nm excimer laser therapy was administered twice a week for 12 weeks. Photograph and phototrichogram analyses were performed. Photographic assessments by both dermatologists and individuals of the general population showed objective improvements after excimer laser therapy. On the treated side, the hair count and hair diameter had statistically increased after treatment. However, only the hair diameter was found to be significantly high in the treated half when it was compared with the control side. The 308-nm excimer laser has a therapeutic effect on AA, which is proven by photograph and phototrichogram analysis by a side-by-side comparison. © 2015 S. Karger AG, Basel.

  13. A comparative study of via drilling and scribing on PEN and PET substrates for flexible electronic applications using excimer and Nd:YAG laser sources

    NARCIS (Netherlands)

    Mandamparambil, R.; Fledderus, H.; Brand, J. van den; Saalmink, M.; Kusters, R.; Podprocky, T.; Steenberge, G. van; Baets, J. de; Dietzel, A.H.

    2009-01-01

    A study on via drilling and channel scribing on PEN and PET substrates for flexible electronic application is discussed in this paper. For the experiments, both KIF excimer laser (248 nm) and frequency tripled Nd:YAG (355 nm) laser are used. Different measurement techniques like optical microscopy,

  14. Excimer laser sintering of indium tin oxide nanoparticles for fabricating thin films of variable thickness on flexible substrates

    International Nuclear Information System (INIS)

    Park, Taesoon; Kim, Dongsik

    2015-01-01

    Technology to fabricate electrically-conducting, transparent thin-film patterns on flexible substrates has possible applications in flexible electronics. In this work, a pulsed-laser sintering process applicable to indium tin oxide (ITO) thin-film fabrication on a substrate without thermal damage to the substrate was developed. A nanosecond pulsed laser was used to minimize thermal penetration into the substrate and to control the thickness of the sintered layer. ITO nanoparticles (NPs) of ~ 20 nm diameter were used to lower the process temperature by exploiting their low melting point. ITO thin film patterns were fabricated by first spin coating the NPs onto a surface, then sintering them using a KrF excimer laser. The sintered films were characterized using field emission scanning electron microscopy. The electrical resistivity and transparency of the film were measured by varying the process parameters. A single laser pulse could generate the polycrystalline structure (average grain size ~ 200 nm), reducing the electrical resistivity of the film by a factor of ~ 1000. The sintering process led to a minimum resistivity of 1.1 × 10 −4 Ω·m without losing the transparency of the film. The thickness of the sintered layer could be varied up to 150 nm by adjusting the laser fluence. Because the estimated thermal penetration depth in the ITO film was less than 200 nm, no thermal damage was observed in the substrate. This work suggests that the proposed process, combined with various particle deposition methods, can be an effective tool to form thin-film ITO patterns on flexible substrates. - Highlights: • Excimer laser sintering can fabricate ITO thin films on flexible substrates. • The laser pulse can form a polycrystalline structure without thermal damage. • The laser sintering process can reduce the electrical resistivity substantially. • The thickness of the sintered layer can be varied effectively

  15. Excimer laser sintering of indium tin oxide nanoparticles for fabricating thin films of variable thickness on flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Park, Taesoon; Kim, Dongsik, E-mail: dskim87@postech.ac.kr

    2015-03-02

    Technology to fabricate electrically-conducting, transparent thin-film patterns on flexible substrates has possible applications in flexible electronics. In this work, a pulsed-laser sintering process applicable to indium tin oxide (ITO) thin-film fabrication on a substrate without thermal damage to the substrate was developed. A nanosecond pulsed laser was used to minimize thermal penetration into the substrate and to control the thickness of the sintered layer. ITO nanoparticles (NPs) of ~ 20 nm diameter were used to lower the process temperature by exploiting their low melting point. ITO thin film patterns were fabricated by first spin coating the NPs onto a surface, then sintering them using a KrF excimer laser. The sintered films were characterized using field emission scanning electron microscopy. The electrical resistivity and transparency of the film were measured by varying the process parameters. A single laser pulse could generate the polycrystalline structure (average grain size ~ 200 nm), reducing the electrical resistivity of the film by a factor of ~ 1000. The sintering process led to a minimum resistivity of 1.1 × 10{sup −4} Ω·m without losing the transparency of the film. The thickness of the sintered layer could be varied up to 150 nm by adjusting the laser fluence. Because the estimated thermal penetration depth in the ITO film was less than 200 nm, no thermal damage was observed in the substrate. This work suggests that the proposed process, combined with various particle deposition methods, can be an effective tool to form thin-film ITO patterns on flexible substrates. - Highlights: • Excimer laser sintering can fabricate ITO thin films on flexible substrates. • The laser pulse can form a polycrystalline structure without thermal damage. • The laser sintering process can reduce the electrical resistivity substantially. • The thickness of the sintered layer can be varied effectively.

  16. Single application on iris localization technology in excimer laser for astigmatism

    Directory of Open Access Journals (Sweden)

    Jun-Hua Hao

    2014-06-01

    Full Text Available AIM:To discuss the single application on iris localization technology in excimer laser for the treatment of astigmatism. METHODS:Totally 203 cases(406 eyesof laser in situ keratomileusis(LASIKin the treatment of compound myopic astigmatism patients were operated from November 2011 to November 2012 in our hospital. They were divided into two groups. One was observation group using iris localization and the other was control group using routine operation. Patients in the observation group of 100 cases(200 eyes, aged 18-43 years old, spherical diopter was -1.25 to -8.75D, astigmatism was -1.0 to -3.25D. In control group, 103 patients(206 eyes, aged 19-44 years old, spherical diopter was -1.75-9.50D, astigmatism was -1.0 to -3.25D. The patients in the observation group before the application of WaveScan aberrometer check for iris image, spherical lens, cylindrical lens and astigmatism axis data operation, only single application of iris location, without using wavefront aberration guided technology, laser cutting patterns for conventional LASIK model, spherical, cylindrical mirror and astigmatism axis data source to preoperative wavefront aberration results. The control group received routine LASIK. It was applicated comprehensive optometry optometry respectively to examine astigmatism and axial, based on the computer analysis during the preoperative, 1wk after the operation, and 6mo. Analysis of using SPSS 17 statistical software, it was independent-sample t test between the two groups of residual astigmatism and astigmatism axis. RESULTS:Postoperative residual astigmatism, the observation group was significantly better than the control group. Astigmatism axial measurement after operation, the observation group was significantly less than that of the control group. Postoperative visual acuity at 6mo, the observation group was better than that of the control group. The difference was statistically significant. CONCLUSION: For patients who cannot

  17. Excimer laser micropatterning of freestanding thermo-responsive hydrogel layers for cells-on-chip applications

    International Nuclear Information System (INIS)

    Santaniello, Tommaso; Milani, Paolo; Lenardi, Cristina; Martello, Federico; Tocchio, Alessandro; Gassa, Federico; Webb, Patrick

    2012-01-01

    We report a novel reliable and repeatable technologic manufacturing protocol for the realization of micro-patterned freestanding hydrogel layers based on thermo-responsive poly-(N-isopropyl)acrylamide (PNIPAAm), which have potential to be employed as temperature-triggered smart surfaces for cells-on-chip applications. PNIPAAm-based films with controlled mechanical properties and different thicknesses (100–300 µm thickness) were prepared by injection compression moulding at room temperature. A 9 × 9 array of 20 µm diameter through-holes is machined by means of the KrF excimer laser on dry PNIPAAm films which are physically attached to flat polyvinyl chloride (PVC) substrates. Machining parameters, such as fluence and number of shots, are optimized in order to achieve highly resolved features. Micro-structured freestanding films are then easily obtained after hydrogels are detached from PVC by gradually promoting the film swelling in ethanol. In the PNIPAAm water-swollen state, the machined holes’ diameter approaches a slight larger value (30 µm) according to the measured hydrogel swelling ratio. Thermo-responsive behaviour and through-hole tapering characterization are carried out by metrology measurements using an optical inverted and confocal microscope setup, respectively. After the temperature of freestanding films is raised above 32 °C, we observe that the shrinkage of the whole through-hole array occurs, thus reducing the holes’ diameter to less than a half its original size (about 15 µm) as a consequence of the film dehydration. Different holes’ diameters (10 and 30 µm) are also obtained on dry hydrogel employing suitable projection masks, showing similar shrinking behaviour when hydrated and undergone thermo-response tests. Thermo-responsive PNIPAAm-based freestanding layers could then be integrated with other suitable micro-fabricated thermoplastic components in order to preliminary test their feasibility in operating as temperature

  18. The effect of excimer laser keratectomy on corneal glutathione peroxidase activities and aqueous humor selenium levels in rabbits.

    Science.gov (United States)

    Yis, Ozgür; Bilgihan, Ayşe; Bilgihan, Kamil; Yis, Nilgün Safak; Hasanreisoğlu, Berati

    2002-06-01

    The formation of free oxygen radicals has been demonstrated in the corneal tissue after 193 nm laser irradiation. Cornea has several defense mechanisms that protect against oxidative damage. One of them, glutathione peroxidase (GPx), catalyzes the destruction of hydrogen peroxide and lipid hydroperoxide. Selenium is a trace element which is incorporated into the selenoenzyme GPx. In the present study, the effect of excimer laser keratectomy on corneal GPx activities and aqueous humor selenium concentrations in rabbits was evaluated. Animals were divided into five groups, and all groups were compared: controls (group 1), after epithelial scraping (group 2), transepithelial photorefractive keratectomy(PRK; group 3), superficial traditional PRK (50 microm; group 4) and deep traditional PRK (100 microm; group 5). Corneal GPx activities were measured by a modification of the coupled assay procedure. Aqueous humor selenium concentrations were determined using hydride generation atomic absorption spectrometry. Corneal GPx activities were significantly lower only in group 5 ( P<0.05), and the selenium concentration in the aqueous humor did not change in any group. Deep corneal photoablation inhibits GPx enzyme activities in the cornea. Therefore, antioxidants may be useful in reducing free radical-mediated complications after excimer laser corneal photoablation.

  19. Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150 deg. C

    International Nuclear Information System (INIS)

    Park, Joong-Hyun; Han, Sang-Myeon; Park, Sang-Geun; Han, Min-Koo; Shin, Moon-Young

    2006-01-01

    Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200 deg. C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200 deg. C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150 deg. C. We employed various buffer layers, such as silicon nitride (SiN X ) and silicon dioxide (SiO 2 ), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,λ=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiN X buffer layer is wider than SiO 2 and the maximum grain size slightly increased

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

    International Nuclear Information System (INIS)

    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.

  1. Time-resolved diagnostics of excimer laser-generated ablation plasmas used for pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Geohegan, D.B.

    1994-09-01

    Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO, BN, graphite and Si in vacuum and background gases. The implementation and advantages of the four techniques are first described in order to introduce the key features of laser plasmas for pulsed laser deposition. Aspects of the interaction of the ablation plume with background gases (i.e., thermalization, attenuation, shock formation) and the collision of the plasma plume with the substrate heater are then summarized. The techniques of fast ICCD photography and gated photon counting are then applied to investigate the temperature, velocity, and spatial distribution of hot particles generated during KrF ablation of YBCO, BN, Si and graphite. Finally, key features of fast imaging of the laser ablation of graphite into high pressure rare gases are presented in order to elucidate internal reflected shocks within the plume, redeposition of material on a surface, and formation of hot nanoparticles within the plume.

  2. Time-resolved diagnostics of excimer laser-generated ablation plasmas used for pulsed laser deposition

    International Nuclear Information System (INIS)

    Geohegan, D.B.

    1994-01-01

    Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO, BN, graphite and Si in vacuum and background gases. The implementation and advantages of the four techniques are first described in order to introduce the key features of laser plasmas for pulsed laser deposition. Aspects of the interaction of the ablation plume with background gases (i.e., thermalization, attenuation, shock formation) and the collision of the plasma plume with the substrate heater are then summarized. The techniques of fast ICCD photography and gated photon counting are then applied to investigate the temperature, velocity, and spatial distribution of hot particles generated during KrF ablation of YBCO, BN, Si and graphite. Finally, key features of fast imaging of the laser ablation of graphite into high pressure rare gases are presented in order to elucidate internal reflected shocks within the plume, redeposition of material on a surface, and formation of hot nanoparticles within the plume

  3. SF{sub 6} decomposition and layer formation due to excimer laser photoablation of SiO{sub 2} surface at gas-solid system

    Energy Technology Data Exchange (ETDEWEB)

    Sajad, Batool [Physics Department, Amirkabir University, PO Box 15875-4413, Tehran (Iran, Islamic Republic of); Parvin, Parviz [Physics Department, Amirkabir University, PO Box 15875-4413, Tehran (Iran, Islamic Republic of); Bassam, Mohamad Amin [Excimer Laser Lab, Emam Hussain University, PO Box 16575-4347, Tehrann (Iran, Islamic Republic of)

    2004-12-21

    In this work, the effect of an excimer laser has been studied for presenting a method for SF{sub 6} decomposition and simultaneous formation of a SiF{sub 2} layer on amorphous SiO{sub 2}. Though the excimer laser did not establish a gas phase photodissociation, we have shown that UV photoablation leads strongly to molecular decomposition in the SF{sub 6}-SiO{sub 2} system. Moreover, the dependence of the decomposition process on the exposure parameters such as the wavelength and intensity as well as the gas pressure and the focal point distance from the gas-solid interface has been investigated.

  4. Endobronchial Forceps-Assisted and Excimer Laser-Assisted Inferior Vena Cava Filter Removal: The Data, Where We Are, and How It Is Done.

    Science.gov (United States)

    Chen, James X; Montgomery, Jennifer; McLennan, Gordon; Stavropoulos, S William

    2018-06-01

    The recognition of inferior vena cava filter related complications has motivated increased attentiveness in clinical follow-up of patients with inferior vena cava filters and has led to development of multiple approaches for retrieving filters that are challenging or impossible to remove using conventional techniques. Endobronchial forceps and excimer lasers are tools for designed to aid in complex inferior vena cava filter removals. This article discusses endobronchial forceps-assisted and excimer laser-assisted inferior vena cava filter retrievals. Copyright © 2018 Elsevier Inc. All rights reserved.

  5. Update on excimer laser photorefractive keratectomy (PRK) at Cedars-Sinai Medical Center: two-year experience

    Science.gov (United States)

    Maguen, Ezra I.; Salz, James J.; Warren, Cathy; Papaioannou, Thanassis; Nesburn, Anthony B.; Macy, Jonathan I.; Hofbauer, John; Grundfest, Warren S.

    1993-06-01

    Our two year experience with excimer laser photorefractive keratectomy for the correction of myopia on 160 eyes of 128 patients is described. All eyes were treated with a VISX Twenty- Twenty excimer laser, with the following parameters: radiant exposure 160 mJ/cm2, frequency 5 Hz, ablation zone diameter 5.0 to 5.5 mm, and stromal ablation rate 0.18 to 0.33 (mu) /pulse. A suction fixation ring was used in all cases either with nitrogen flow (79 eyes) or without nitrogen flow (81 eyes) across the cornea. Follow-up ranged from one month (152 eyes) to 24 months (12 eyes). The results are stable between 3 and 24 months with less than 0.25 D change in the mean postoperative spherical equivalents. In eyes with a follow-up of 6 to 24 months, 77% to 100% were 20/40 or better uncorrected, and 84% to 92% were corrected to within +/- 1 D of emmetropia. Further follow-up is needed to assess the long term safety and efficacy of the procedure.

  6. How predictable are the results of excimer laser photorefractive keratectomy? A review.

    Science.gov (United States)

    Grosvenor, T

    1995-10-01

    At the close of 1994, the AOA News reported that at least 14 companies were preparing to market equipment for excimer laser photorefractive keratectomy (PRK). More than a dozen PRK centers had been formed for the purpose of recruiting optometrists to co-manage PRK patients. Because the surgery is a "no-touch" computer-driven procedure whose duration is measured in seconds, the preoperative and postoperative care of PRK patients will assume major importance. Optometrists who will be asked to take part in the management of PRK patients must be able to counsel patients on matters such as the predictability of the procedure in terms of postoperative refractive error and visual acuity, as well as the possibility of unintended consequences such as difficulty in night driving. Information currently available, mainly as a result of studies conducted in other countries, shows that the results of PRK are highly predictable for preoperative myopia up to about -3.00 D and somewhat less predictable for myopia between -3.00 and -6.00 D, whereas for myopia greater than -6.00 D the probability of achieving a full correction decreases rapidly with increasing amounts of myopia. As compared to radial keratotomy (RK) in which the postoperative refractive error drifts relentlessly in the hyperopic direction, PRK brings about an initial hyperopic shift followed by regression leading to increasing myopia. Researchers disagree on the cause of the postoperative hyperopic shift and regression, and on the value of various methods of controlling regression including the use of wider and deeper ablation profiles and the postoperative use of corticosteroids and nonsteroid anti-inflammatory drugs. It is too early to determine whether the myopic creep in PRK will be as persistent as the hyperopic creep in RK, but it is likely that whereas presbyopic post-RK patients may have adequate distance vision but require corrective lenses for reading, presbyopic post-PRK patients may be sufficiently myopic

  7. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    International Nuclear Information System (INIS)

    Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

    2002-01-01

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment

  8. One-kilohertz eye tracker and active intraoperative torsion detection in the NIDEK CXIII and Quest excimer lasers.

    Science.gov (United States)

    Waring, George O

    2009-10-01

    To describe recent technological additions to the NIDEK CXIII and Quest excimer lasers. A summary article with data from previous published studies outlining the benefits of newer technology. The addition of a 1-kHz infrared eye tracker decreased the spread of laser spot placement from a mean of 228.79 microm without a tracker to 38.47 microm with the eye tracker. The addition of real-time torsion error correction produced a statistically significantly lower cylinder dispersion, mean manifest refractive cylinder, and error of angle postoperatively in eyes that underwent LASIK. The incorporation of an ultrahigh speed eye tracker and active cyclotorsion correction surpasses the minimal technology criteria required for accurate wavefront-based ablations. Copyright 2009, SLACK Incorporated.

  9. Improving the ablation efficiency of excimer laser systems with higher repetition rates through enhanced debris removal and optimized spot pattern.

    Science.gov (United States)

    Arba-Mosquera, Samuel; Klinner, Thomas

    2014-03-01

    To evaluate the reasons for the required increased radiant exposure for higher-repetition-rate excimer lasers and determine experimentally possible compensations to achieve equivalent ablation profiles maintaining the same single-pulse energies and radiant exposures for laser repetition rates ranging from 430 to 1000 Hz. Schwind eye-tech-solutions GmbH and Co. KG, Kleinostheim, Germany. Experimental study. Poly(methyl methacrylate) (PMMA) plates were photoablated. The pulse laser energy was maintained during all experiments; the effects of the flow of the debris removal, the shot pattern for the correction, and precooling the PMMA plates were evaluated in terms of achieved ablation versus repetition rate. The mean ablation performance ranged from 88% to 100%; the variability between the profile measurements ranged from 1.4% to 6.2%. Increasing the laser repetition rate from 430 Hz to 1000 Hz reduced the mean ablation performance from 98% to 91% and worsened the variability from 1.9% to 4.3%. Increasing the flow of the debris removal, precooling the PMMA plates to -18°C, and adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the variability. Only adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the mean ablation performance. The ablation performance of higher-repetition-rate excimer lasers on PMMA improved with improvements in the debris removal systems and shot pattern. More powerful debris removal systems and smart shot patterns in terms of thermal response improved the performance of these excimer lasers. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  10. Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

    International Nuclear Information System (INIS)

    Gentile, C.A.; Fan, H.M.; Hartfield, J.W.; Hawryluk, R.J.; Hegeler, F.; Heitzenroeder, P.J.; Jun, C.H.; Ku, L.P.; LaMarche, P.H.; Myers, M.C.; Parker, J.J.; Parsells, R.F.; Payen, M.; Raftopoulos, S.; Sethian, J.D.

    2002-01-01

    The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, , and ) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W · cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated with 500 nm thin-film silicon nitride (Si 3 N 4 ), has been fabricated. The window consists of 81 square panes with a thickness of 0.019 mm ± 0.001 mm. Stiffened (orthogonal) sections are 0.065 mm in width and 0.500 mm thick (approximate). Appended drawing (Figure 1) depicts the window configuration. Assessment of silicon (and silicon nitride) material properties and CAD modeling and analysis of the window design suggest that silicon may be a viable solution to inherent parameters and constraints

  11. Excimer laser phototherapeutic keratectomy : Indications, results and its role in the Indian scenario

    Directory of Open Access Journals (Sweden)

    Rao Srinivas

    1999-01-01

    Full Text Available PURPOSE: To report indications, technique, and results of excimer phototherapeutic keratectomy (PTK, and describe possible reasons for the small numbers of such procedures performed in a referral institute in India. METHODS: Retrospective review of case records of 10 patients (11 eyes who underwent excimer PTK at our institute between February 1994 and September 1997. RESULTS: Corneal scars were the most common indication for treatment. Best-corrected visual acuity (BCVA improved in 6 eyes (mean: 2 lines of Snellen acuity. All eyes had BCVA > or = 6/12 after treatment. None of the patients experienced loss of BCVA after treatment. Unaided visual acuity improved in 3 eyes and decreased in 2 eyes. Change in spherical equivalent refraction > or = 1 diopter occurred in 77.8% of eyes after treatment. Treating central corneal scars resulted in a significant hyperopic shift in refraction. CONCLUSIONS: Excimer PTK is a safe and effective procedure for the treatment of superficial corneal opacities. Post-treatment ametropia may require further correction with optical aids. Inappropriate referrals, deep corneal scars, and cost of the procedure could have contributed to the small numbers of PTK performed at our institute. Improved understanding of procedural strengths and limitations could lead to increased use of this procedure, with satisfying results in selected patients.

  12. Investigations of an excimer laser working with a four-component gaseous mixture He-Kr:Xe-HCl

    Science.gov (United States)

    Iwanejko, Leszek; Pokora, Ludwik J.

    1991-08-01

    The paper presnts working conditions of an XCI excimer laser untypical gas mixture based on KrzXe instead of pure Xe. Such a choice was influenced by the necessity of Findin9 the way to replace imported and expensive Xe by gaseous components accesible in Poland. Determining the range of changes of laser extrnal parameters which enables its proper work with the new gas mixture was the aim of same investigations results of which are presented in this paper. The laser pulse output energy and the pulse duration as a Function of supply voltage and the mixture composition are presented. The range of proper conditions for the laser working with the new mixture He-Kr:Xe--HC1 was determined. The analysis of experimental results showed that using the new mixture ensures value of energy and pulse duration comparable with the ones obtained for the mixture He-''Xe--HCl. Spectral investigations showed the lack of influence of Kr presence in the mixture on the generation spectrum of the laser. L.

  13. Excimer laser processing of inkjet-printed and sputter-deposited transparent conducting SnO2:Sb for flexible electronics

    International Nuclear Information System (INIS)

    Cranton, Wayne M.; Wilson, Sharron L.; Ranson, Robert; Koutsogeorgis, Demosthenes C.; Chi Kuangnan; Hedgley, Richard; Scott, John; Lipiec, Stephen; Spiller, Andrew; Speakman, Stuart

    2007-01-01

    The feasibility of low-temperature fabrication of transparent electrode elements from thin films of antimony-doped tin oxide (SnO 2 :Sb, ATO) has been investigated via inkjet printing, rf magnetron sputtering and post-deposition excimer laser processing. Laser processing of thin films on both glass and plastic substrates was performed using a Lambda Physik 305i excimer laser, with fluences in the range 20-100 mJ cm -2 reducing sheet resistance from as-deposited values by up to 3 orders of magnitude. This is consistent with TEM analysis of the films that shows a densification of the upper 200 nm of laser-processed regions

  14. AFM study of excimer laser patterning of block-copolymer: Creation of ordered hierarchical, hybrid, or recessed structures

    International Nuclear Information System (INIS)

    Švanda, Jan; Siegel, Jakub; Švorčík, Vaclav; Lyutakov, Oleksiy

    2016-01-01

    Highlights: • Combination of bottom-up (BCP separation) and top-down (laser patterning) technologies allows obtaining hierarchical structures. • Surface morphologies were determined by the order of patterning steps (laser modification, annealing, surface reconstruction). • Tuning the order of steps enables the reorientation of BCP domain at large scale, fabrication of hierarchical, hybrid or recessed structures. • The obtained structures can find potential applications in nanotechnology, plasmonics, information storage, sensors and smart surfaces. - Abstract: We report fabrication of the varied range of hierarchical structures by combining bottom-up self-assembly of block copolymer poly(styrene-block-vinylpyridine) (PS-b-P4VP) with top-down excimer laser patterning method. Different procedures were tested, where laser treatment was applied before phase separation and after phase separation or phase separation and surface reconstruction. Laser treatment was performed using either polarized laser light with the aim to create periodical pattern on polymer surface or non-polarized light for preferential removing of polystyrene (PS) part from PS-b-P4VP. Additionally, dye was introduced into one part of block copolymer (P4VP) with the aim to modify its response to laser light. Resulting structures were analyzed by XPS, UV–vis and AFM techniques. Application of polarized laser light leads to creation of structures with hierarchical, recessed or hybrid geometries. Non-polarized laser beam allows pronouncing the block copolymer phase separated structure. Tuning the order of steps or individual step conditions enables the efficient reorientation of block-copolymer domain at large scale, fabrication of hierarchical, hybrid or recessed structures. The obtained structures can find potential applications in nanotechnology, photonics, plasmonics, information storage, optical devices, sensors and smart surfaces.

  15. Suppression of dewetting phenomena during excimer laser melting of thin metal films on SiO2

    International Nuclear Information System (INIS)

    Kline, J.E.; Leonard, J.P.

    2005-01-01

    Pulsed excimer laser irradiation has been used to fully melt 200 nm films of elemental Au and Ni on SiO 2 substrates. With the use of a capping layer of SiO 2 and line irradiation via projection optics, the typical liquid-phase dewetting processes associated with these metals on SiO 2 has been suppressed. In a series of experiments varying line widths and fluence, a process region is revealed immediately above the complete melting threshold for which the films remain continuous and smooth after melting and resolidification. Simple energetic arguments for mechanisms leading to initiation of dewetting support these observations, and a gas-mediated model is proposed to describe the process conditions that are necessary for the suppression of dewetting

  16. Preparation of PZT/YBCO/YAlO heterostructure thin films by KrF excimer laser ablation

    International Nuclear Information System (INIS)

    Ebihara, Kenji; Kurogi, Hiromitsu; Yamagata, Yukihiko; Ikegami, Tomoaki; Grishin, A.M.

    1998-01-01

    The perovskite oxide YBa 2 Cu 3 O 7-x (YBCO) and Pb(Zr x Ti 1-x )O 3 (PZT) thin films have been deposited for superconducting-ferroelectric devices. KrF excimer laser ablation technique was used at the deposition conditions of 200--600 mTorr O 2 , 2-3J/cm 2 and 5--10 Hz operation frequency. Heterostructures of PZT-YBCO-YAlO 3 :Nd show the zero resistivity critical temperature of 82 K and excellent ferroelectric properties of remnant polarization 32 microC/cm 2 , coercive force of 80 kV/cm and dielectric constant 800. Cycling fatigue characteristics and leakage current are also discussed

  17. Dopant redistribution and electrical activation in silicon following ultra-low energy boron implantation and excimer laser annealing

    International Nuclear Information System (INIS)

    Whelan, S.; La Magna, A.; Privitera, V.; Mannino, G.; Italia, M.; Bongiorno, C.; Fortunato, G.; Mariucci, L.

    2003-01-01

    Excimer laser annealing (ELA) of ultra-low-energy (ULE) B-ion implanted Si has been performed. High-resolution transmission electron microscopy has been used to assess the as-implanted damage and the crystal recovery following ELA. The electrical activation and redistribution of B in Si during ELA has been investigated as a function of the laser energy density (melted depth), the implant dose, and the number of laser pulses (melt time). The activated and retained dose has been evaluated with spreading resistance profiling and secondary ion mass spectrometry. A significant amount of the implanted dopant was lost from the sample during ELA. However, the dopant that was retained in crystal material was fully activated following rapid resolidification. At an atomic concentration below the thermodynamic limit, the activation efficiency (dose activated/dose implanted into Si material) was a constant for a fixed melt depth, irrespective of the dose implanted and hence the total activated dose was raised as the implant dose was increased. The electrical activation was increased for high laser energy density annealing when the dopant was redistributed over a deeper range

  18. Screening for psychiatric distress and low self-esteem in patients presenting for excimer laser surgery for myopia.

    Science.gov (United States)

    Kidd, B; Stark, C; McGhee, C N

    1997-01-01

    Patients presenting for photorefractive keratectomy (PRK) may have unusual psychological profiles. Certain psychological variables may impact treatment outcome, making early identification crucial. We report a controlled questionnaire study of psychiatric "anxiety/distress" and self-esteem in myopic patients who presented for excimer laser treatment. Ninety consecutive myopic individuals (patients) who presented for excimer laser PRK and 50 consecutive myopic individuals who presented to an optometrist for contact lens fitting (controls) were assessed using two self-completion questionnaires-the GHQ30 and Hudson Index of Self-Esteem ISE. The questionnaires were distributed during assessment for treatment. PRK patients had a 90% response rate for both questionnaires and control patients, 98% for GHQ30 and 100% for Hudson ISE. PRK patients were significantly older (p = 0.000003), had a greater myopic spherical equivalent refraction (p = 0.012) and had better spectacle-corrected visual acuity (p = 0.0096). No significant differences were demonstrated with regard to anxiety/distress in terms of absolute scores (p = 0.07), or the proportion of patients being positive or negative (p = 0.10). Similarly, self-esteem was not significantly different between the two groups (absolute scores p = 0.69; positive/negative p = 0.29). The high response rate shows that the GHQ30 and Hudson ISE are easy to use and well tolerated by myopes in a busy clinic setting. The fact that the patients were older, with a greater refractive error, may partly reflect the onset of contact lens intolerance. The psychological findings suggest that PRK patients cannot be considered more distressed or anxious than other myopic individuals. There is no evidence that their decision to undergo surgery is driven by abnormally low self-esteem.

  19. Study on Laser Induced Plasma Produced in Liquid

    International Nuclear Information System (INIS)

    Tsuda, N.; Yamada, J.

    2003-01-01

    When an intense laser light is focused in liquid, a hot plasma is produced at the focal spot. The breakdown threshold and the transmittance of sodium choroids solution are observed using excimer laser or YAG laser. The breakdown threshold decreases with increasing NaCl concentration. Threshold intensity of plasma produced by YAG laser is lower than excimer laser. The behavior of plasma development is observed by a streak camera. The plasma produced by a YAG laser develops only backward. However, the plasma produced by excimer laser develops not only backward but also forward same as the plasma development in high-pressure gases

  20. EFFECT OF OPTICAL FIBER HYDROGEN LOADING ON THE INSCRIPTION EFFICIENCY OF CHIRPED BRAGG GRATINGS BY MEANS OF KrF EXCIMER LASER RADIATION

    Directory of Open Access Journals (Sweden)

    Sergey V. Varzhel

    2016-11-01

    Full Text Available Subject of Research.We present comparative results of the chirped Bragg gratings inscription efficiency in optical fiber of domestic production with and without low-temperature hydrogen loading. Method. Chirped fiber Bragg gratings inscription was made by the Talbot interferometer with chirped phase mask having a chirp rate of 2.3 nm/cm used for the laser beam amplitude separation. The excimer laser system Coherent COMPexPro 150T, working with the gas mixture KrF (248 nm, was used as the radiation source. In order to increase the UV photosensitivity, the optical fiber was placed in a chamber with hydrogen under a pressure of 10 MPa and kept there for 14 days at 40 °C. Main Results. The usage of the chirped phase mask in a Talbot interferometer scheme has made it possible to get a full width at half-maximum of the fiber Bragg grating reflection spectrum of 3.5 nm with induced diffraction structure length of 5 mm. By preliminary hydrogen loading of optical fiber the broad reflection spectrum fiber Bragg gratings with a reflectivity close to 100% has been inscribed. Practical Relevance. The resulting chirped fiber Bragg gratings can be used as dispersion compensators in optical fiber communications, as well as the reflective elements of distributed fiber-optic phase interferometric sensors.

  1. Surface studies on benzophenone doped PDMS microstructures fabricated using KrF excimer laser direct write lithography

    Energy Technology Data Exchange (ETDEWEB)

    Kant, Madhushree Bute; Shinde, Shashikant D. [Department of Physics, University of Pune, Pune 411007 (India); Bodas, Dhananjay [Centre for Nanobioscience, Agharkar Research Institute, Agharkar road, Pune 411004 (India); Patil, K.R. [Center for Materials Characterization, National Chemical Laboratories, Pune 411008 (India); Sathe, V.G. [UGC DAE Inter University Consortium, Indore 452017 (India); Adhi, K.P. [Department of Physics, University of Pune, Pune 411007 (India); Gosavi, S.W., E-mail: swg@physics.unipune.ac.in [Department of Physics, University of Pune, Pune 411007 (India)

    2014-09-30

    Graphical abstract: - Highlights: • Use of KrF Laser micromachining for Lab-On-Chip applications at lower fluence. • Addition of Benzophenone in PDMS enhances its self development sensitivity. • Benzophenone helps efficient energy transfer for equal density of bond scissioning. • Correlation of chemical composition with laser dose and microstructure. • Microstructures with well defined clean sidewalls. - Abstract: This paper discusses microfabrication process for benzophenone doped polydimethylsiloxane (PDMS) using laser lithography. KrF excimer laser of 248 nm with 20 ns pulse width at repetition rate of 1 Hz was used for microfabrication of undoped and benzophenone doped PDMS. The doped-PDMS shows sensitivity below 365 nm, permitting processing under ambient light. The analysis of etch depth revealed that doped PDMS shows self developable sensitivity at lower fluence of ∼250 mJ/cm{sup 2}. The unexposed and exposed surface was studied using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Scanning electron microscopy (SEM). Spectrocopic analysis indicated increase in C-O, C=O, Si-O{sub 3} and Si-O{sub 4} bonding at the expense of Si-C and Si-O{sub 2} bonds of PDMS. In case of laser exposed doped-PDMS, removal of benzophenone from probe depth of spectroscopy was observed. Whereas the surface morphology of exposed and unexposed doped-PDMS was observed to be same, indicating clean development of PDMS micropatterns. The present study indicates that addition of 3.0 wt.% benzophenone in PDMS enhance self development sensitivity of PDMS. The self developable results on doped-PDMS are quite encouraging for its potential use in point of care Lab-On-Chip applications, for fabricating micropatterns using direct write laser lithography technology.

  2. Surface studies on benzophenone doped PDMS microstructures fabricated using KrF excimer laser direct write lithography

    International Nuclear Information System (INIS)

    Kant, Madhushree Bute; Shinde, Shashikant D.; Bodas, Dhananjay; Patil, K.R.; Sathe, V.G.; Adhi, K.P.; Gosavi, S.W.

    2014-01-01

    Graphical abstract: - Highlights: • Use of KrF Laser micromachining for Lab-On-Chip applications at lower fluence. • Addition of Benzophenone in PDMS enhances its self development sensitivity. • Benzophenone helps efficient energy transfer for equal density of bond scissioning. • Correlation of chemical composition with laser dose and microstructure. • Microstructures with well defined clean sidewalls. - Abstract: This paper discusses microfabrication process for benzophenone doped polydimethylsiloxane (PDMS) using laser lithography. KrF excimer laser of 248 nm with 20 ns pulse width at repetition rate of 1 Hz was used for microfabrication of undoped and benzophenone doped PDMS. The doped-PDMS shows sensitivity below 365 nm, permitting processing under ambient light. The analysis of etch depth revealed that doped PDMS shows self developable sensitivity at lower fluence of ∼250 mJ/cm 2 . The unexposed and exposed surface was studied using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Scanning electron microscopy (SEM). Spectrocopic analysis indicated increase in C-O, C=O, Si-O 3 and Si-O 4 bonding at the expense of Si-C and Si-O 2 bonds of PDMS. In case of laser exposed doped-PDMS, removal of benzophenone from probe depth of spectroscopy was observed. Whereas the surface morphology of exposed and unexposed doped-PDMS was observed to be same, indicating clean development of PDMS micropatterns. The present study indicates that addition of 3.0 wt.% benzophenone in PDMS enhance self development sensitivity of PDMS. The self developable results on doped-PDMS are quite encouraging for its potential use in point of care Lab-On-Chip applications, for fabricating micropatterns using direct write laser lithography technology

  3. Photochemically induced deposition of protective alumina coatings onto UV emitting phosphors for Xe excimer discharge lamps

    International Nuclear Information System (INIS)

    Broxtermann, Mike; Jüstel, Thomas

    2016-01-01

    Highlights: • A UV-reactor for the pH induced precipitation of inorganic material is described. • The photolysis of Azide (N_3"−) leads to a steady pH increase used for precipitation. • A UV induced Al(OH)_3 precipitation is used to craft Al_2O_3 coatings onto YPO_4:Bi. • The influence of Al_2O_3 coated onto YPO_4:Bi with different thicknesses is discussed. • SEM, VUV-spectroscopy and ESA measurements were performed on Al_2O_3 coated samples. - Abstract: This work concerns the particle coating of the UV-C emitting phosphor YPO_4:Bi, targeting a stability enhancement of the phosphor material for Xe excimer lamp operation. To this end, the material is coated by the wide band gap material Al_2O_3. In order to obtain a thin and homogeneous coating layer, a novel process based on the photochemical cleavage of NaN_3 in water was developed. This results in a slow and continuous enhancement of the pH value due to ongoing NaOH formation, which results in the precipitation of Al(OH)_3 from an Al_2(SO_4)_3 _× 18H_2O solution. It turned out that the obtained particle coatings are of much better quality, i.e. homogeneity, compared to coatings made from a wet-chemical homogeneous precipitation process. The morphology and electrochemical properties of Al_2O_3 coated YPO_4:Bi are discussed on the basis of optical spectroscopy, ESA measurements, and SEM/EDX investigations.

  4. Photochemically induced deposition of protective alumina coatings onto UV emitting phosphors for Xe excimer discharge lamps

    Energy Technology Data Exchange (ETDEWEB)

    Broxtermann, Mike, E-mail: mike.b@fh-muenster.de; Jüstel, Thomas, E-mail: tj@fh-muenster.de

    2016-08-15

    Highlights: • A UV-reactor for the pH induced precipitation of inorganic material is described. • The photolysis of Azide (N{sub 3}{sup −}) leads to a steady pH increase used for precipitation. • A UV induced Al(OH){sub 3} precipitation is used to craft Al{sub 2}O{sub 3} coatings onto YPO{sub 4}:Bi. • The influence of Al{sub 2}O{sub 3} coated onto YPO{sub 4}:Bi with different thicknesses is discussed. • SEM, VUV-spectroscopy and ESA measurements were performed on Al{sub 2}O{sub 3} coated samples. - Abstract: This work concerns the particle coating of the UV-C emitting phosphor YPO{sub 4}:Bi, targeting a stability enhancement of the phosphor material for Xe excimer lamp operation. To this end, the material is coated by the wide band gap material Al{sub 2}O{sub 3}. In order to obtain a thin and homogeneous coating layer, a novel process based on the photochemical cleavage of NaN{sub 3} in water was developed. This results in a slow and continuous enhancement of the pH value due to ongoing NaOH formation, which results in the precipitation of Al(OH){sub 3} from an Al{sub 2}(SO{sub 4}){sub 3} {sub ×} 18H{sub 2}O solution. It turned out that the obtained particle coatings are of much better quality, i.e. homogeneity, compared to coatings made from a wet-chemical homogeneous precipitation process. The morphology and electrochemical properties of Al{sub 2}O{sub 3} coated YPO{sub 4}:Bi are discussed on the basis of optical spectroscopy, ESA measurements, and SEM/EDX investigations.

  5. Randomized controlled study of excimer laser atherectomy for treatment of femoropopliteal in-stent restenosis: initial results from the EXCITE ISR trial (EXCImer Laser Randomized Controlled Study for Treatment of FemoropopliTEal In-Stent Restenosis).

    Science.gov (United States)

    Dippel, Eric J; Makam, Prakash; Kovach, Richard; George, Jon C; Patlola, Raghotham; Metzger, D Christopher; Mena-Hurtado, Carlos; Beasley, Robert; Soukas, Peter; Colon-Hernandez, Pedro J; Stark, Matthew A; Walker, Craig

    2015-01-01

    The purpose of this study was to evaluate the safety and efficacy of excimer laser atherectomy (ELA) with adjunctive percutaneous transluminal angioplasty (PTA) versus PTA alone for treating patients with chronic peripheral artery disease with femoropopliteal bare nitinol in-stent restenosis (ISR). Femoropopliteal stenting has shown superiority to PTA for lifestyle-limiting claudication and critical limb ischemia, although treating post-stenting artery reobstruction, or ISR, remains challenging. The multicenter, prospective, randomized, controlled EXCITE ISR (EXCImer Laser Randomized Controlled Study for Treatment of FemoropopliTEal In-Stent Restenosis) trial was conducted across 40 U.S. centers. Patients with Rutherford Class 1 to 4 and lesions of target lesion length ≥4 cm, vessel diameter 5 to 7 mm were enrolled and randomly divided into ELA + PTA and PTA groups by a 2:1 ratio. The primary efficacy endpoint was target lesion revascularization (TLR) at 6-month follow up. The primary safety endpoint was major adverse event (death, amputation, or TLR) at 30 days post-procedure. Study enrollment was stopped at 250 patients due to early efficacy demonstrated at a prospectively-specified interim analysis. A total of 169 ELA + PTA subjects (62.7% male; mean age 68.5 ± 9.8 years) and 81 PTA patients (61.7% male; mean age 67.8 ± 10.3 years) were enrolled. Mean lesion length was 19.6 ± 12.0 cm versus 19.3 ± 11.9 cm, and 30.5% versus 36.8% of patients exhibited total occlusion. ELA + PTA subjects demonstrated superior procedural success (93.5% vs. 82.7%; p = 0.01) with significantly fewer procedural complications. ELA + PTA and PTA subject 6-month freedom from TLR was 73.5% versus 51.8% (p < 0.005), and 30-day major adverse event rates were 5.8% versus 20.5% (p < 0.001), respectively. ELA + PTA was associated with a 52% reduction in TLR (hazard ratio: 0.48; 95% confidence interval: 0.31 to 0.74). The EXCITE ISR trial is the first large, prospective, randomized study

  6. Measurement of radiation and temperature of cathod spots in excimer laser discharge; Ekishima reza reiki hodennai ni fukumareru inkyoku kiten no kogakuteki kansoku to ondo no sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Minamitani, Y.; Nakatani, H. [Mitsubishi Electric Corp., Tokyo (Japan)

    1996-08-20

    Excimer laser is used in various fields such as luminous source for steppers, annealing treatment, ablation process, nuclear fusion and so on. In this paper, the radiation timing and gas temperature of cathode spots, streamer discharges and glow discharges in KrF excimer are measured by observing the radiating spectra thereof. The following conclusions are obtained from the results of the present study. Cathode spots begin to radiate at about 20ns after the discharge initiation, then the first and second radiation peaks are observed respectively when the discharge current reversing after passing zero point and the reserved discharged current approaching zero point. Streamer discharge makes flashover between electrodes at the second radiation peak of cathode spots, while the glow discharges almost disappear when streamer discharges occurring. The temperatures of cathode spots and glow discharge as 5500K and 2600K respectively are almost constant and independent upon the discharging voltage of laser. 14 refs., 12 figs.

  7. Metal surface nitriding by laser induced plasma

    Science.gov (United States)

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

    1996-10-01

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

  8. Gasochromic performance of WO{sub 3}-nanorod thin films fabricated with an ArF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Yaacob, M. H. [RMIT University, Melbourne (Australia); Universiti Putra Malaysia, Selangor (Malaysia); Ou, J. Z.; Wlodarski, W. [RMIT University, Melbourne (Australia); Kim, C. S.; Lee, J. Y. [KAIST, Daejon (Korea, Republic of); Kim, Y. H. [KIST, Seoul (Korea, Republic of); Oh, C. M.; Dhakal, K. P.; Kim, J. Y.; Kang, J. H. [University of Incheon, Incheon (Korea, Republic of)

    2012-02-15

    Thin films with tungsten trioxide (WO{sub 3}) nanorods were fabricated by using an ArF pulsed laser deposition system. Because the ArF excimer laser operates at a very short wavelength of 193 nm, short enough to expect strong absorption of the photons in the semiconductor oxide targets, and because the clusters incoming to the substrates have high momentum, we could build thin films with good surface morphology. Highly homogeneous arrays of nanorods with sizes mostly in the range of 30 - 40 nm were observed. The absorbance response towards hydrogen (H{sub 2}) gas was investigated for a WO{sub 3} film coated with 25-A-thick palladium (Pd). The Pd/WO{sub 3}-nanorod thin films exhibited excellent gasochromic response when measured in the visible-NIR range (400 - 1000 nm). As low as 0.06% H{sub 2} concentration was clearly sensed. A significant reversible absorbance change and fast recovery (<2 min) were observed when the films were exposed to H{sub 2} at different concentrations.

  9. Four-year to seven-year outcomes of advanced surface ablation with excimer laser for high myopia

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob

    2015-01-01

    Purpose: To evaluate and compare long-term outcomes ofafter photorefractive keratectomy with cooling (cPRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopia. Methods: Retrospective single-masked follow-up study of patients treated for myopia between 2007 and 2009 with cPRK...... or LASEK, using a high-frequency flying-spot excimer laser with eye-tracker (MEL80; Carl Zeiss, Jena, Germany). One eye of each patient was randomly chosen for analysis. Re-treated eyes were excluded. Results: Forty-six cPRK patients and 35 LASEK patients were included. Spherical equivalent averaged -7.......69 ± 1.47 diopters (D) in cPRK eyes and -7.98 ± 2.06 D in LASEK eyes (P=0.31) before surgery. Average follow-up time was 4.6 years in cPRK patients and 6.0 years in LASEK patients (PPRK eyes and 1 LASEK eye (P=0.46) had lost 2 lines of corrected distance visual acuity...

  10. Studies of free radicals by ultraviolet excimer laser photolysis. Progress report, 1 April 1980-1 November 1980

    International Nuclear Information System (INIS)

    Leone, S.R.

    1980-01-01

    An experimental technique has been developed to produce and directly study vibrationally excited free radicals. Pulses of light from an ultraviolet excimer laser are used to photodissociate small molecules to generate free radicals with high internal excitation. The radicals are detected directly by the technique of time and wavelength-resolved infrared emission spectroscopy using a background-limited copper-doped germanium infrared detector. New results have been obtained on the CH 3 radical. A complete spectrum of the CH 3 umbrella band reveals for the first time accurate positions of the vibrational progression in this band. Photofragmentation of (CH 3 ) 2 Hg has yielded detailed information on the vibrational distribution, rotational temperature, and deactivation rates of the CH 3 stretch mode. A technique to study chemical chain reactions using low power, radical-specific, laser initiation and realtime kinetics detection had previously been demonstrated. The results provide a general method to study a large number of chain reaction combustion systems in greater detail. New results on more complex chain reactions such as Cl 2 /butane reveal that highly detailed infrared emission spectra of various products of the chain and their time evolution is possible. Partitioning of energy between vibrational degrees of freedom and translational heating is obtained over the course of the combustion

  11. Applying low-energy multipulse excimer laser annealing to improve charge retention of Au nanocrystals embedded MOS capacitors

    International Nuclear Information System (INIS)

    Shen, Kuan-Yuan; Chen, Hung-Ming; Liao, Ting-Wei; Kuan, Chieh-Hsiung

    2015-01-01

    The low-energy multipulse excimer laser annealing (LEM-ELA) is proposed to anneal the nanostructure of nanocrystal (NC) embedded in a SiO 2 thin film without causing atomic diffusion and damaging the NCs, since the LEM-ELA combining the advantages of laser annealing and UV curing features rapid heating and increasing oxide network connectivity. A Fourier transform infrared spectroscopy (FTIR) characterization of SiO 2 thin films annealed using LEM-ELA indicated that the quality was improved through the removal of water-related impurities and the reconstruction of the network Si–O–Si bonds. Then, LEM-ELA was applied to a SiO 2 thin film embedded with Au NCs, which were fabricated as MOS capacitors. The charge retention was greatly improved and the percentage of retained charges was about 10% after 3  ×  10 8  s. To investigate and differentiate the effects of LEM-ELA on charges stored in both oxide traps and in the Au NCs, a double-mechanism charge relaxation analysis was performed. The results indicated that the oxide traps were removed and the confinement ability of Au NCs was enhanced. The separated memory windows contributed from the charges in Au NCs and those in oxide traps were obtained and further confirmed that the LEM-ELA removed oxide traps without damaging the Au NCs. (paper)

  12. ArF excimer laser modulation of TNF-alpha and gelatinase B in NIH 3T3 cells; Modulation de l`expression du TNF-alpha et de la gelatinase B, apres irradiation de fibroblastes NIH 3T3 par un laser a excimeres a 193 NM

    Energy Technology Data Exchange (ETDEWEB)

    Naudy-Vives, C.; Courant, D.; Perot, J.C.; Garcia, J.; Fretier, P.; Court, L.; Dormont, D.

    1995-12-31

    The effects on TNF-alpha and gelatinase B activity in mammalian cells induced by 193 nm argon fluoride excimer laser have been investigated. The data show that a secretion of 92 kDa type IV collagenase and TNF-alpha were increased in cell culture supernatants. Moreover, the 193 nm laser radiation produces a decrease of cell proliferation and an increase of cell activation 8 hours after irradiation. The total protein amount increases with the delivered dose. Same, but less effects were obtained after exposure to a conventional UV lamp at 254 nm. (author). 8 refs.

  13. Possibilities and limitations of optical fibers for the transmission of excimer laser radiation

    International Nuclear Information System (INIS)

    Klein, K.F.; Hillrichs, G.; Karlitschek, P.; Mann, K.

    1997-01-01

    For fiber-delivery systems with UV-lasers the candidates are mainly optical fibers with an undoped high-OH silica core and a F-doped silica cladding. However, there are three important limits to UV-applications: surface damage, two-photon-absorption and defect-generation during operation. In the last two years, UV-improved fibers with significantly reduced defects have been developed. This improvement is most pronounced at 248 and 193 nm, because at these critical wavelengths the induced losses are strongly influenced by the main broadband UV-defects with absorption maxima at 165 nm and 215 nm. We will summarize the results including the influence of the main parameters. In addition, the transmission capacity for the 308 nm wavelength is of interest due to medical and industrial applications. At this wavelength the influence of the nonlinearities is much lower; however, the induced losses in standard fibers are still an important factor. To show the advantages of the UV-improved fibers, the transmission characteristics at 308 nm wavelength will be described in more detail, for the first time

  14. A retrospective comparison of efficacy and safety of 680 consecutive lasik treatments for high myopia performed with two generations of flying-spot excimer lasers.

    Science.gov (United States)

    Gazieva, Lola; Beer, Mette Hjuler; Nielsen, Kim; Hjortdal, Jesper

    2011-12-01

    To compare the visual refractive outcome and complication of laser in situ keratomileusis (LASIK) carried out with a Carl Zeiss-Meditec MEL-70 Excimer laser and a MEL-80 laser for treatment of high myopia. Journal records of 680 consecutive eyes that underwent LASIK with a Schwind Supratome microkeratome and a MEL-70 Excimer laser (Group A), or a Moria M2 microkeratome and a MEL-80 Excimer laser (Group B) were reviewed. Manifest refraction, uncorrected and best spectacle-corrected visual acuity (BSCVA), corneal topography and central corneal thickness (CCT) were recorded before and 3 months after treatment. Pre- and postoperative complications, visual and refractive outcome and frequency of retreatments were registered. Mean preoperative spherical equivalent refraction was -8.52 dioptres (-5.50- -18 dioptres), and the mean attempted laser correction was -8.02 dioptres (-5.50- -11 dioptres). Three months after LASIK, the average treatment error (difference between achieved and attempted correction) was 1.20 (SD=1.19) dioptres of under correction in Group A and 0.52 (SD=1.00) dioptres in Group B. Four eyes lost more than two lines of BSCVA (0.6%). In 110 eyes (16%), a re-LASIK procedure was performed to reduce remaining myopia after the primary procedure. Laser in situ keratomileusis treatment for high myopia can effectively reduce high degrees of myopia. Under correction was observed in both treatment groups but Group B has a slightly better predictability. Significant loss of BSCVA occurs infrequently after LASIK for even considerable grades of myopia (0.6% in each group). © 2010 The Authors. Journal compilation © 2010 Acta Ophthalmol.

  15. Preliminary results of tracked photorefractive keratectomy (T-PRK) for mild to moderate myopia with the autonomous technologies excimer laser at Cedars-Sinai Medical Center

    Science.gov (United States)

    Maguen, Ezra I.; Salz, James J.; Nesburn, Anthony B.

    1997-05-01

    Preliminary results of the correction of myopia up to -7.00 D by tracked photorefractive keratectomy (T-PRK) with a scanning and tracking excimer laser by Autonomous Technologies are discussed. 41 eyes participated (20 males). 28 eyes were evaluated one month postop. At epithelization day mean uncorrected vision was 20/45.3. At one month postop, 92.8 of eyes were 20/40 and 46.4% were 20/20. No eye was worse than 20/50. 75% of eyes were within +/- 0.5 D of emmetropia and 82% were within +/- 1.00 D of emmetropia. Eyes corrected for monovision were included. One eye lost 3 lines of best corrected vision, and had more than 1.00 D induced astigmatism due to a central corneal ulcer. Additional complications included symptomatic recurrent corneal erosions which were controlled with topical hypertonic saline. T-PRK appears to allow effective correction of low to moderate myopia. Further study will establish safety and efficacy of the procedure.

  16. Laser-induced interactions

    International Nuclear Information System (INIS)

    Green, W.R.

    1979-01-01

    This dissertation discusses some of the new ways that lasers can be used to control the energy flow in a medium. Experimental and theoretical considerations of the laser-induced collision are discussed. The laser-induced collision is a process in which a laser is used to selectively transfer energy from a state in one atomic or molecular species to another state in a different species. The first experimental demonstration of this process is described, along with later experiments in which lasers were used to create collisional cross sections as large as 10 - 13 cm 2 . Laser-induced collisions utilizing both a dipole-dipole interaction and dipole-quadrupole interaction have been experimentally demonstrated. The theoretical aspects of other related processes such as laser-induced spin-exchange, collision induced Raman emission, and laser-induced charge transfer are discussed. Experimental systems that could be used to demonstrate these various processes are presented. An experiment which produced an inversion of the resonance line of an ion by optical pumping of the neutral atom is described. This type of scheme has been proposed as a possible method for constructing VUV and x-ray lasers

  17. Properties of the ablation process for excimer laser ablation of Y sub 1 Ba sub 2 Cu sub 3 O sub 7

    Energy Technology Data Exchange (ETDEWEB)

    Neifeld, R.A.; Potenziani, E. (United States Army, Electronics Technology and Devices Laboratory, Fort Monmouth, New Jersey 07703-5000 (US)); Sinclair, W.R. (Martin Goffman Associates, 3 Dellview Drive, Edison, New Jersey 08820-2545 (US)); Hill III, W.T.; Turner, B.; Pinkas, A. (Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (US))

    1991-01-15

    The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm{sup 2}. Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm{sup 2}. Several of the parameters measured vary rapidly in the 1--5 J/cm{sup 2} range. Variation in these parameters strongly influences the properties of films grown by this technique.

  18. INDEPENDENT EVALUATION OF THE GAM EX5ALN MINIATURE LINE-NARROWED KRF EXCIMER LASER

    Science.gov (United States)

    2017-06-01

    reliant on digital communication, perhaps a simple downloadable video ( YouTube ) could be prepared to facilitate the installation procedures. At a...prolonged use influenced the laser output. The stability of the laser under conditions of high discharge voltages and rapid firing rates was examined

  19. Characteristics of thin-film transistors based on silicon nitride passivation by excimer laser direct patterning

    International Nuclear Information System (INIS)

    Chen, Chao-Nan; Huang, Jung-Jie

    2013-01-01

    This study explored the removal of silicon nitride using KrF laser ablation technology with a high threshold fluence of 990 mJ/cm 2 . This technology was used for contact hole patterning to fabricate SiN x -passivation-based amorphous-silicon thin films in a transistor device. Compared to the photolithography process, laser direct patterning using KrF laser ablation technology can reduce the number of process steps by at least three. Experimental results showed that the mobility and threshold voltages of thin film transistors patterned using the laser process were 0.16 cm 2 /V-sec and 0.2 V, respectively. The device performance and the test results of gate voltage stress reliability demonstrated that laser direct patterning is a promising alternative to photolithography in the panel manufacturing of thin-film transistors for liquid crystal displays. - Highlights: ► KrF laser ablation technology is used to remove silicon nitride. ► A simple method for direct patterning contact-hole in thin-film-transistor device. ► Laser technology reduced processing by at least three steps

  20. LASEK for the correction of hyperopia with mitomycin C using SCHWIND AMARIS excimer laser: one-year follow-up

    Directory of Open Access Journals (Sweden)

    Khosrow Jadidi

    2015-11-01

    Full Text Available AIM: To evaluate the efficacy, safety and predictability of laser-assisted sub-epithelial keratectomy(LASEKfor the correction of hyperopia using the SCHWIND AMARIS platform.METHODS: This retrospective single-surgeon study includes 66 eyes of 33 patients with hyperopia who underwent LASEK with mitomycin C(MMC. The median age of patients was 35.42±1.12y(ranging 18 to 56y. In each patient LASEK was performed using SCHWIND AMARIS excimer laser. Postoperatively clinical outcomes were evaluated in terms of predictability, safety, efficacy, subjective and objective refractions, uncorrected visual acuity(UCVA, best spectacle-corrected visual acuity(BSCVAand adverse events. RESULTS: The mean baseline refraction was 3.2±1.6 diopters(D(ranging 0 to 7 D. The mean pre-operative and postoperative spherical equivalent(SEwere 2.34±1.76(ranging -1.25 to 7 Dand 0.30±0.84(ranging -0.2 to 0.8 Drespectively(P=0.001. The mean hyperopia was 0.63±0.84 D(ranging -1.75 to 2.76 D6 to 12mo postoperatively. Likewise, the mean astigmatism was 0.68±0.43 D(range 0 to 2 Dwith 51(77.3%and 15(22.7%eyes within ±1 and ±0.50 D respectively. The safety index and efficacy index were 1.08 and 1.6 respectively.CONCLUSION:LASEK using SCHWIND AMARIS with MMC yields good visual and refractive results for hyperopia. Moreover, there were no serious complications.

  1. Ablation, surface activation, and electroless metallization of insulating materials by pulsed excimer laser irradiation

    International Nuclear Information System (INIS)

    Lowndes, D.H.; Godbole, M.J.; Pedraza, A.J.

    1993-01-01

    Pulsed-laser irradiation of wide bandgap ceramic substrates, using photons with sub-bandgap energies, activates the ceramic surface for subsequent electroless copper deposition. The copper deposit is confined within the irradiated region when the substrate is subsequently immersed in an electroless copper bath. However, a high laser fluence (typically several j/cm 2 ) and repeated laser shots are needed to obtain uniform copper coverage by this direct-irradiation process. In contrast, by first applying an evaporated SiO x thin film (with x ∼1), laser ablation at quite low energy density (∼0.5 J/cm 2 ) results in re-deposition on the ceramic substrate of material that is catalytic for subsequent electroless copper deposition. Experiments indicate that the re-deposited material is on silicon, on which copper nucleates. Using an SiO x film on a laser-transparent substrate, quite fine (∼12 μm) copper lines can be formed at the boundary of the region that is laser-etched in SiO x . Using SiO x with an absorbing (polycrystalline) ceramic substrate, more-or-less uniform activation and subsequent copper deposition are obtained. In the later case, interactions with the ceramic substrate also may be important for uniform deposition

  2. [Reduction of decentration after LASIK using a modified eye tracker ring for the MEL-70 excimer laser].

    Science.gov (United States)

    Schulze, S; Nietgen, G; Sekundo, W

    2004-07-01

    The aim of this study was to determine and compare the rate of eccentric laser ablation after LASIK depending on the eye tracker ring used. All LASIK treatments were carried out using the MEL-70 flying spot excimer laser (Zeiss-Meditec, Jena). The flap was produced using a Corneal Shaper trade mark or Hansatome trade mark Microkeratome (B and L Surgical, Heidelberg). Initially we used an 11 mm eye tracker ring without hinge protector. At the end of February 2001 this ring was replaced by a 10 mm and a 9.5 mm ring with built-in hinge protector. An additional modification was introduced by us: at 1 mm separations little teeth-like spikes were engraved into the eyeward side of the ring, thus stabilising the position of the ring on the globe and allowing free liquid to flow through the spaces between each spike. The built-in calibration system of the corneal topography (TMS 3, Tomey, Erlangen) from patients with a follow-up of one month or longer was used to determine the distance between the centre of the ablation zone from the fixation point. In group I patients (old ring) 42 eyes were treated. In 4 eyes ablation was perfect, in 21 eyes the ablation centre was located 0.1 to 0.49 mm from the fixation point, in 11 eyes 0.51 to 0.99 mm and in 5 eyes 1.1 to 1.49 mm whereas one eye showed a decentred ablation of 1.53 mm. In group II (new ring) 42 eyes were investigated also. In 11 eyes ablation was perfect, in 20 eyes the ablation centre was located 0.1 to 0.49 mm from the fixation point, in 10 eyes 0.5 to 0.99 mm and one eye had an eccentric ablation of 1.28 mm from the fixation point. The further development of our eye tracker ring for the MEL-70 laser considerably reduced the rate of decentred ablations. An enhanced grip of the ring onto the globe reduces a slow slide during the laser procedure.

  3. X-ray spectral line shapes for the excimer-laser-produced high density plasma diagnostics

    International Nuclear Information System (INIS)

    Magunov, A.; Faenov, A.; Skobelev, I.; Pikuz, T.; Batani, D.; Milani, M.; Conti, A.; Masini, A.; Costato, M.; Pozzi, A.; Turcu, E.; Allot, R.; Lisi, N.; Koenig, M.; Benuzzi, A.; Flora, F.; Letardi, T.; Palladino, L.; Reale, A.

    1997-01-01

    The time and space-integrated emission spectra measurements have been performed in plasma produced by 308 nm wavelength XeCl laser radiation (I L =(4-10)·10 12 W/cm 2 , τ=10 ns) and by 248 nm wavelength KrF laser pulse train radiation (I L =5·10 15 W/cm 2 , τ=7 ps, 16 pulses in train) on CF n plane target. The lines' shapes and intensities modeling of Lyman series and He-like ion resonance series of fluorine up to n=7 by fitting experimental data shows the considerable difference of plasma formation features for these two sets of the laser pulse parameters

  4. Modeling of solid-state and excimer laser processes for 3D micromachining

    Science.gov (United States)

    Holmes, Andrew S.; Onischenko, Alexander I.; George, David S.; Pedder, James E.

    2005-04-01

    An efficient simulation method has recently been developed for multi-pulse ablation processes. This is based on pulse-by-pulse propagation of the machined surface according to one of several phenomenological models for the laser-material interaction. The technique allows quantitative predictions to be made about the surface shapes of complex machined parts, given only a minimal set of input data for parameter calibration. In the case of direct-write machining of polymers or glasses with ns-duration pulses, this data set can typically be limited to the surface profiles of a small number of standard test patterns. The use of phenomenological models for the laser-material interaction, calibrated by experimental feedback, allows fast simulation, and can achieve a high degree of accuracy for certain combinations of material, laser and geometry. In this paper, the capabilities and limitations of the approach are discussed, and recent results are presented for structures machined in SU8 photoresist.

  5. 80 A/cm2 electron beams from metal targets irradiated by KrCl and XeCl excimer lasers

    Science.gov (United States)

    Beloglazov, A.; Martino, M.; Nassisi, V.

    1996-05-01

    Due to the growing demand for high-current and long-duration electron-beam devices, laser electron sources were investigated in our laboratory. Experiments on electron-beam generation and propagation from aluminium and copper targets illuminated by XeCl (308 nm) and KrCl (222 nm) excimer lasers, were carried out under plasma ignition due to laser irradiation. This plasma supplied a spontaneous accelerating electric field of about 370 kV/m without an external accelerating voltage. By applying the modified one-dimensional Poisson equation, we computed the expected current and we also estimated the plasma concentration during the accelerating process. At 40 kV of accelerating voltage, an output current pulse of about 80 A/cm2 was detected from an Al target irradiated by the shorter wavelength laser.

  6. Laser induced energy transfer

    International Nuclear Information System (INIS)

    Falcone, R.W.

    1979-01-01

    Two related methods of rapidly transferring stored energy from one excited chemical species to another are described. The first of these, called a laser induced collision, involves a reaction in which the energy balance is met by photons from an intense laser beam. A collision cross section of ca 10 - 17 cm 2 was induced in an experiment which demonstrated the predicted dependence of the cross section on wavelength and power density of the applied laser. A second type of laser induced energy transfer involves the inelastic scattering of laser radiation from energetically excited atoms, and subsequent absorption of the scattered light by a second species. The technique of producing the light, ''anti-Stokes Raman'' scattering of visible and infrared wavelength laser photons, is shown to be an efficient source of narrow bandwidth, high brightness, tunable radiation at vacuum ultraviolet wavelengths by using it to excite a rare gas transition at 583.7 A. In addition, this light source was used to make the first measurement of the isotopic shift of the helium metastable level at 601 A. Applications in laser controlled chemistry and spectroscopy, and proposals for new types of lasers using these two energy transfer methods are discussed

  7. Single photon excimer laser photodissociation of highly vibrationally excited polyatomic molecules

    International Nuclear Information System (INIS)

    Tiee, J.J.; Wampler, F.B.; Rice, W.W.

    1980-01-01

    The ir + uv photodissociation of SF 6 has been performed using CO 2 and ArF lasers. The two-color photolysis significantly enhances the photodissociation process over ArF irradiation alone and is found to preserve the initial isotopic specificity of the ir excitation process

  8. Laser induced nuclear reactions

    International Nuclear Information System (INIS)

    Ledingham, Ken; McCanny, Tom; Graham, Paul; Fang Xiao; Singhal, Ravi; Magill, Joe; Creswell, Alan; Sanderson, David; Allott, Ric; Neely, David; Norreys, Peter; Santala, Marko; Zepf, Matthew; Watts, Ian; Clark, Eugene; Krushelnick, Karl; Tatarakis, Michael; Dangor, Bucker; Machecek, Antonin; Wark, Justin

    1998-01-01

    Dramatic improvements in laser technology since 1984 have revolutionised high power laser technology. Application of chirped-pulse amplification techniques has resulted in laser intensities in excess of 10 19 W/cm 2 . In the mid to late eighties, C. K. Rhodes and K. Boyer discussed the possibility of shining laser light of this intensity onto solid surfaces and to cause nuclear transitions. In particular, irradiation of a uranium target could induce electro- and photofission in the focal region of the laser. In this paper it is shown that μCi of 62 Cu can be generated via the (γ,n) reaction by a laser with an intensity of about 10 19 Wcm -2

  9. Some actinide speciation using laser induced photoacoustic spectroscopy

    International Nuclear Information System (INIS)

    Pollard, P.M.; McMillan, J.W.; Phillips, G.; Thomason, H.P.; Ewart, F.T.

    1988-01-01

    Laser induced photoacoustic spectroscopy is an attractive method for the speciation of actinides in solutions from nuclear disposal studies because it is essentially non-invasive and has a reasonably high sensitivity, down to ca 10 -8 M. A novel true dual beam system has been constructed and commissioned at Harwell with a performance at least equal to any others in existence. It is based on a XeCl excimer laser and a dye laser, beam splitter, two laser power monitors and photoacoustic cells. The wavelength scanning, data collection, and spectra processing and display are controlled by an Apricot computer. The sample and reference cells are housed in an inert atmosphere glove box. Early applications of the equipment described include measurements of Am and Np species under varying conditions of pH, Eh and carbonate concentration. The observations show some correlation with predictions made using the geochemical modelling code PHREEQE. (orig.)

  10. The study of metal-alloy targets and excimer laser deposition technology

    International Nuclear Information System (INIS)

    Xu Hua; Wu Weidong; Tang Xiaohong; Zhang Jicheng; Tang Yongjian

    2002-01-01

    Pulsed Laser Deposition (PLD) technology is described. Design and manufacture of the PLD installation is illustrated in detail. The Cu films and Cu/Fe multi-layers are produced by PLD method. The production of the Mg/Si films using magnetron sputtering method is investigated in detail. The percent of Si on Mg/Si film surface is measured by using conductivity method

  11. Diode laser probe of CO2 vibrational excitation produced by collisions with hot deuterium atoms from the 193 nm excimer laser photolysis D2S

    International Nuclear Information System (INIS)

    O'Neill, J.A.; Cai, J.Y.; Flynn, G.W.; Weston, R.E. Jr.

    1986-01-01

    The 193 nm excimer laser photolysis of D 2 S in D 2 S/CO 2 mixtures produces fast deuterium atoms (E/sub TR/approx.2.2 eV) which vibrationally excite CO 2 molecules via inelastic translation--vibration/rotation (T--V/R) energy exchange processes. A high resolution (10 -3 cm -1 ) cw diode laser probe was used to monitor the excitation of ν 3 (antisymmetric stretch) and ν 2 (bend) vibrations in CO 2 . The present results are compared with previous experiments involving hot hydrogen atom excitation of CO 2 in H 2 S/CO 2 mixtures as well as with theoretical calculations of the excitation probability. The probability for excitation of a ν 3 quantum in CO 2 is about 1%--2% per gas kinetic D/CO 2 collision. Bending (ν 2 ) quanta are produced about eight times more efficiently than antisymmetric stretching (ν 3 ) quanta. The thermalization rate for cooling hot D atoms below the threshold for production of a ν 3 vibrational quantum corresponds to less than 2 D*/D 2 S collisions or 15 D*/CO 2 collisions

  12. Comparison of boron diffusion in silicon during shallow p{sup +}/n junction formation by non-melt excimer and green laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Aid, Siti Rahmah; Matsumoto, Satoru [Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Fuse, Genshu [SEN Corporation, SBS Tower 9F, 4-10-1 Yoga, Setagaya-ku, Tokyo 158-0097 (Japan); Sakuragi, Susumu [Sumitomo Heavy Industries Ltd., 19 Natsushima-cho, Yokosuka, Kanagawa 237-8555 (Japan)

    2011-12-15

    The combination of Ge pre-amorphization implantation, low-energy boron implantation, and non-melt laser annealing is a promising method for forming ultrashallow p{sup +}/n junctions in silicon. In this study, shallow p{sup +}/n junctions were formed by non-melt annealing implanted samples using a green laser (visible laser). The dopant diffusion, activation, and recrystallization of an amorphous silicon layer were compared with those obtained in our previous study in which non-melt annealing was performed using a KrF excimer laser (UV laser). The experimental results reveal that only slight diffusion of boron in the tail region occurred in green-laser-annealed samples. In contrast, remarkable boron diffusion occurred in KrF-laser-annealed samples for very short annealing times. Recrystallization of the amorphous silicon layer was slower in green-laser-annealed samples than in KrF-laser-annealed samples. We consider the penetration depth and the pulse duration are important factors that may affect boron diffusion. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Four-year to seven-year outcomes of advanced surface ablation with excimer laser for high myopia.

    Science.gov (United States)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob; Grønbech, Keea Treu; Vestergaard, Anders Højslet

    2015-07-01

    We aimed to evaluate and compare outcomes after photorefractive keratectomy with cooling (cPRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopia. This was a retrospective, single-masked follow-up study of patients treated for myopia between 2007 and 2009 with cPRK or LASEK, using a high-frequency flying-spot excimer laser with eye-tracker (MEL80; Carl Zeiss, Jena, Germany). One eye of each patient was randomly chosen for analysis. Re-treated eyes were excluded. Forty-six cPRK patients and 35 LASEK patients were included. Spherical equivalent averaged -7.69 ± 1.47 diopters (D) in cPRK eyes and -7.98 ± 2.06 D in LASEK eyes (p = 0.31) before surgery. The average follow-up time was 4.6 years in cPRK patients and 6.0 years in LASEK patients (p < 0.05). At final follow-up, no cPRK eyes and one LASEK eye (p = 0.46) had lost two lines of corrected distance visual acuity (CDVA). No eyes had significant haze at final follow-up, although trace haze was found in four cPRK eyes and six LASEK eyes (p = 0.44). However, at 6 weeks after surgery, zero cPRK eyes and nine LASEK eyes (p < 0.05) had significant haze. At final follow-up, 63 % of cPRK eyes and 35 % of LASEK eyes (p = 0.17) were within ±1.0 D of intended refraction. Finally, 100 % of cPRK patients and 92 % of LASEK patients (p = 0.87) were satisfied or very satisfied with the surgery at final follow-up. cPRK and LASEK seemed safe and with high patient satisfaction 4 to 7 years after surgery for high myopia. However, cPRK was more effective than LASEK in reducing initial significant corneal haze.

  14. High-speed photography of plasma during excimer laser-tissue interaction

    International Nuclear Information System (INIS)

    Murray, Andrea K; Dickinson, Mark R

    2004-01-01

    During high fluence laser-tissue interaction, ablation of tissue occurs, debris is removed from the ablation site and is then ejected at high velocity. This debris may be observed as a combination of luminous plasma and non-luminous plume, both of which have the potential to shield the ablation site. This study examined the role of ablation debris in shielding the tissue and determined its effects on the ablation rate over a range of laser pulse energies, pulse repetition rates and pulse numbers for dentine; the velocity differences between hard and soft tissues were also examined. High-speed photography was carried out at up to 1 x 10 8 frames per second. A maximum velocity of 2.58 ± 0.52 x 10 4 m s -1 was recorded for dentine debris within the first 10 ns following ejection. The maximum duration of tissue shielding due to a single pulse, determined by attenuation of a probe beam, was found to be ∼7 ms, ∼80 μs of which was due to luminous plasma and the remainder due to the non-luminous plume

  15. Excimer laser forward transfer of mammalian cells using a novel triazene absorbing layer

    International Nuclear Information System (INIS)

    Doraiswamy, A.; Narayan, R.J.; Lippert, T.; Urech, L.; Wokaun, A.; Nagel, M.; Hopp, B.; Dinescu, M.; Modi, R.; Auyeung, R.C.Y.; Chrisey, D.B.

    2006-01-01

    We present a novel laser-based approach for developing tissue engineered constructs and other cell-based assembly's. We have deposited mesoscopic patterns of viable B35 neuroblasts using a soft direct approach of the matrix assisted pulsed laser evaporation direct write (MAPLE DW) process. As a development of the conventional direct write process, an intermediate layer of absorbing triazene polymer is used to provide gentler and efficient transfers. Transferred cells were examined for viability and proliferation and compared with that of as-seeded cells to determine the efficacy of the process. Results suggest that successful transfers can be achieved at lower fluences than usual by the incorporation of the intermediate absorbing layer thus avoiding any damage to cells and other delicate materials. MAPLE DW offers rapid computer-controlled deposition of mesoscopic voxels at high spatial resolutions, with extreme versatility in depositing combinations of natural/synthetic, living/non-living, organic/inorganic and hard/soft materials. Our approach offers a gentle and efficient transfer of viable cells which when combined with a variety of matrix materials allows development of constructs and bioactive systems in bioengineering

  16. Some optical and electron microscope comparative studies of excimer laser-assisted and nonassisted molecular-beam epitaxically grown thin GaAs films on Si

    Science.gov (United States)

    Lao, Pudong; Tang, Wade C.; Rajkumar, K. C.; Guha, S.; Madhukar, A.; Liu, J. K.; Grunthaner, F. J.

    1990-01-01

    The quality of GaAs thin films grown via MBE under pulsed excimer laser irradiation on Si substrates is examined in both laser-irradiated and nonirradiated areas using Raman scattering, Rayleigh scattering, and by photoluminescence (PL), as a function of temperature, and by TEM. The temperature dependence of the PL and Raman peak positions indicates the presence of compressive stress in the thin GaAs films in both laser-irradiated and nonirradiated areas. This indicates incomplete homogeneous strain relaxation by dislocations at the growth temperature. The residual compressive strain at the growth temperature is large enough such that even with the introduction of tensile strain arising from the difference in thermal expansion coefficients of GaAs and Si, a compressive strain is still present at room temperature for these thin GaAs/Si films.

  17. Two-photon equivalent weighting of spatial excimer laser beam profiles

    Science.gov (United States)

    Eva, Eric; Bauer, Harry H.; Metzger, K.; Pfeiffer, A.

    2001-04-01

    Damage in optical materials for semiconductor lithography applications caused by exposure to 248 or 193 nm light is usually two-photon driven, hence it is a nonlinear function of incident intensity. Materials should be tested with flat- topped temporal and spatial laser beam profiles to facilitate interpretation of data, but in reality this is hard to achieve. Sandstrom provided a formula that approximates any given temporal pulse shape with a two- photon equivalent rectangular pulse (Second Symposium on 193 nm Lithography, Colorado Springs 1997). Known as the integral-square pulse duration, this definition has been embraced as an industry standard. Originally faced with the problem of comparing results obtained with pseudo-Gaussian spatial profiles to literature data, we found that a general solution for arbitrarily inhomogeneous spatial beam profiles exists which results in a definition much similar to Sandstrom's. In addition, we proved the validity of our approach in experiments with intentionally altered beam profiles.

  18. Excimer laser produced plasmas in copper wire targets and water droplets

    Science.gov (United States)

    Song, Kyo-Dong; Alexander, D. R.

    1994-01-01

    Elastically scattered incident radiation (ESIR) from a copper wire target illuminated by a KrF laser pulse at lambda = 248 nm shows a dinstinct two-peak structure which is dependent on the incident energy. The time required to reach the critical electron density (n(sub c) approximately = 1.8 x 10(exp 22) electrons/cu cm) is estimated at 11 ns based on experimental results. Detailed ESIR characteristics for water have been reported previously by the authors. Initiation of the broadband emission for copper plasma begins at 6.5 +/- 1.45 ns after the arrival of the laser pulse. However, the broadband emission occurs at 11 +/- 0.36 ns for water. For a diatomic substance such as water, the electron energy rapidly dissipates due to dissociation of water molecules, which is absent in a monatomic species such as copper. When the energy falls below the excitation energy of the lowest electron state for water, it becomes a subexcitation electron. Lifetimes of the subexcited electrons to the vibrational states are estimated to be of the order of 10(exp -9) s. In addition, the ionization potential of copper (440-530 nm) is approximately 6 eV, which is about two times smaller than the 13 eV ionization potential reported for water. The higher ionization potential contributes to the longer observed delay time for plasma formation in water. After initiation, a longer time is required for copper plasma to reach its peak value. This time delay in reaching the maximum intensity is attributed to the energy loss during the interband transition in copper.

  19. Fast iterative technique for the calculation of frequency dependent gain in excimer laser amplifiers

    International Nuclear Information System (INIS)

    Sze, R.C.

    1991-01-01

    The motivation in initiating these calculations is to allow us to observe the frequency evolution of a laser pulse as it propagates through an amplifier and then through a sequence of amplifiers. The question we seek to answer is what pulse shape do we need to produce out of a front-end oscillator so that after it propagates through the whole Aurora KrF fusion amplifier chain will result in high energy, broad-band laser fields of a given bandwidth that can be focussed onto a fusion target. The propagation of a single frequency source through an amplifier with distributed loss was considered by Rigrod and was significantly expanded by Hunter and Hunter. The latter included amplified spontaneous emission [ASE] considerations both in the direction of and transverse to the coherent field. Analytic solutions that include forward and backward prapagating fields and ASE were derived which were transcendental in nature but allowed for fairly easy computer calculations. Transverse ASE were calculated using the unsaturated gain resulting from longitudinal fields and were used to compare this with the longitudinal field equations. Large computer programs are now available at LANL which include the influence of transverse ASE on the longitudinal fields. However, none of these considerations have worried about the changes in the frequency characteristics of the propagating field or of how each of the frequency field components contributes to the saturation of the gain. The inclusion of full frequency characteristics to the analytic solutions of Hunter and Hunter proved impossible at least for this author and a new calculational technique was developed and is the subject of this talk

  20. EMERGING TECHNOLOGY PROJECT BULLETIN: LASER INDUCED PHOTOCHEMICAL OXIDATIVE DESTRUCTION

    Science.gov (United States)

    The process developed by Energy and Environmental Engineering, Incorporated, is designed to photochemically oxidize organic compounds in wastewater by applying ultraviolet radiation using an Excimer laser. The photochemical reactor can destroy low to moderate concentrations...

  1. Excimer pulsed laser deposition and annealing of YSZ nanometric films on Si substrates

    International Nuclear Information System (INIS)

    Caricato, A.P.; Barucca, G.; Di Cristoforo, A.; Leggieri, G.; Luches, A.; Majni, G.; Martino, M.; Mengucci, P.

    2005-01-01

    We report experimental results obtained for electrical and structural characteristics of yttria-stabilised zirconia (YSZ) thin films deposited by pulsed laser deposition (PLD) on Si substrates at room temperature. Some samples were submitted to thermal treatments in different ambient atmospheres (vacuum, N 2 and O 2 ) at a moderate temperature. The effects of thermal treatments on the film electrical properties were studied by C-V and I-V measurements. Structural characteristics were obtained by X-ray diffraction (XRD), X-ray reflectivity (XRR) and transmission electron microscopy (TEM) analyses. The as-deposited film was amorphous with an in-depth non-uniform density. The annealed films became polycrystalline with a more uniform density. The sample annealed in O 2 was uniform over all the thickness. Electrical characterisation showed large hysteresis, high leakage current and positive charges trapped in the oxide in the as-deposited film. Post-deposition annealing, especially in O 2 atmosphere, improved considerably the electrical properties of the films

  2. Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing

    NARCIS (Netherlands)

    Fujii, M.; Ishikawa, Y.; Ishihara, R.; Van der Cingel, J.; Mofrad, M.R.T.; Horita, M.; Uraoka, Y.

    2013-01-01

    In this study, we successfully achieved a relatively high field-effect mobility of 37.7?cm2/Vs in an InZnO thin-film transistor (TFT) fabricated by excimer layer annealing (ELA). The ELA process allowed us to fabricate such a high-performance InZnO TFT at the substrate temperature less than 50?°C

  3. Simultaneous determinations of U-Pb age and REE abundances for zircons using AfF excimer laser ablation-ICPMS

    International Nuclear Information System (INIS)

    Iizuka, Tsuyoshi; Hirata, Takafumi

    2004-01-01

    Using a laser-ablation-inductively coupled plasma mass spectrometer (LA-ICPMS), U-Pb age and rare earth element (REE) abundances have been determined simultaneously from a single 20 μm ablation pit of zircon. The laser ablation system utilizing 193 nm wave-length ArF excimer laser produces stable and reproducible signal intensities resulted in good precisions on measurements of element concentrations and isotopic ratios. Because of the higher energy density of the deep ultra-violet laser beam, ablation fractionation between Pb and U were reduced even with the prolonged ablation, and thus accuracy of Pb-U age was improved significantly. A chicane-type ion lens system was applied to a quadrupole-based ICPMS instrument. With the chicane ion lens, higher elemental sensitivity (4 times or light mass range and 3 times for mid to heavy mass range) and lower white background ( 238 U- 206 Pb ages for Nancy standard zircon (Nancy 91500), SHRIMP calibration standard zircon (SL13) and Antarctic zircon (PMA7) obtained in this study were 1064 ± 24 Ma, 569 ± 78 Ma and 2438 ± 101 Ma (2-sigma), respectively. Relative age differences from previous reports were 0.2%, 0.4% and 3.2% respectively, demonstrative of high reliability of the method. The REE abundances in zircon samples were calibrated using a NIST 610 glass standard reference material. The resulting REE abundance data for zircons (Nancy 91500 and SL13) show good agreement with those for literature values within the analytical precision of ∼20%. The matrix effect that may occur between the synthetic glass standard and zircon crystals is obviously smaller than the precision and thus negligible for this precision levels. The data presented here demonstrate clearly that the combination of ArF excimer laser an ICPMS equipped with the chicane ion lens has a potential to become a significant tool for zircon geochemistry. (author)

  4. Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

    Science.gov (United States)

    Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

    1993-01-01

    A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

  5. Micromachining of Al2O3-TiC ceramics by excimer laser

    Directory of Open Access Journals (Sweden)

    Oliveira, V.

    1998-04-01

    Full Text Available Micromachining of Al2O3-TiC ceramic using a KrF excimer laser was studied in the fluence range 2 to 8 J/cm2 . The ablation rate decreases and the roughness increases with the first pulses but after about 200 pulses the process reaches a stationary stage where both roughness and ablation rate become constant. Observation of the processed areas by scanning electron microscopy showed that a globular topography is formed during the first stage and that the surface topography remains unchanged with further pulses. This globular topography is responsible for the variation of roughness and ablation rate observed during the first stage. EDS analysis showed that the globular features present an external region with higher titanium content and a core formed of unaffected material.

    Se estudia el micromecanizado de cerámicas Al2O3-TiC mediante un láser de excímero de KrF con un rango de fluencia de 2 a 8 J/cm2 . La velocidad de ablación disminuye y la rugosidad aumenta con los primeros pulsos. Sin embargo, después de 200 pulsos, el proceso alcanza el régimen estacionario, donde tanto la rugosidad como la velocidad de ablación permanecen constantes. La observación mediante SEM de determinadas áreas mostraban una topografía globular formada durante la primera etapa, mientras que con los siguientes pulsos permanece in cambios. Esta topografía globular es responsable de la variación de rugosidad y de la velocidad de ablación observada durante las primeras etapas del proceso. Los análisis de EDS sobre las zonas globulares mostraron la existencia de una región externa rica en titanio y un núcleo formado por el material sin afectar.

  6. Effects of closed immersion filtered water flow velocity on the ablation threshold of bisphenol A polycarbonate during excimer laser machining

    International Nuclear Information System (INIS)

    Dowding, Colin; Lawrence, Jonathan

    2010-01-01

    A closed flowing thick film filtered water immersion technique ensures a controlled geometry for both the optical interfaces of the flowing liquid film and allows repeatable control of flow-rate during machining. This has the action of preventing splashing, ensures repeatable machining conditions and allows control of liquid flow velocity. To investigate the impact of this technique on ablation threshold, bisphenol A polycarbonate samples have been machined using KrF excimer laser radiation passing through a medium of filtered water flowing at a number of flow velocities, that are controllable by modifying the liquid flow-rates. An average decrease in ablation threshold of 7.5% when using turbulent flow velocity regime closed thick film filtered water immersed ablation, compared to ablation using a similar beam in ambient air; however, the use of laminar flow velocities resulted in negligible differences between closed flowing thick film filtered water immersion and ambient air. Plotting the recorded threshold fluence achieved with varying flow velocity showed that an optimum flow velocity of 3.00 m/s existed which yielded a minimum ablation threshold of 112 mJ/cm 2 . This is attributed to the distortion of the ablation plume effected by the flowing immersion fluid changing the ablation mechanism: at laminar flow velocities Bremsstrahlung attenuation decreases etch rate, at excessive flow velocities the plume is completely destroyed, removing the effect of plume etching. Laminar flow velocity regime ablation is limited by slow removal of debris causing a non-linear etch rate over 'n' pulses which is a result of debris produced by one pulse remaining suspended over the feature for the next pulse. The impact of closed thick film filtered water immersed ablation is dependant upon beam fluence: high fluence beams achieved greater etch efficiency at high flow velocities as the effect of Bremsstrahlung attenuation is removed by the action of the fluid on the plume; low

  7. Influence of spatial and temporal spot distribution on the ocular surface quality and maximum ablation depth after photoablation with a 1050 Hz excimer laser system.

    Science.gov (United States)

    Mrochen, Michael; Schelling, Urs; Wuellner, Christian; Donitzky, Christof

    2009-02-01

    To investigate the effect of temporal and spatial distributions of laser spots (scan sequences) on the corneal surface quality after ablation and the maximum ablation of a given refractive correction after photoablation with a high-repetition-rate scanning-spot laser. IROC AG, Zurich, Switzerland, and WaveLight AG, Erlangen, Germany. Bovine corneas and poly(methyl methacrylate) (PMMA) plates were photoablated using a 1050 Hz excimer laser prototype for corneal laser surgery. Four temporal and spatial spot distributions (scan sequences) with different temporal overlapping factors were created for 3 myopic, 3 hyperopic, and 3 phototherapeutic keratectomy ablation profiles. Surface quality and maximum ablation depth were measured using a surface profiling system. The surface quality factor increased (rough surfaces) as the amount of temporal overlapping in the scan sequence and the amount of correction increased. The rise in surface quality factor was less for bovine corneas than for PMMA. The scan sequence might cause systematic substructures at the surface of the ablated material depending on the overlapping factor. The maximum ablation varied within the scan sequence. The temporal and spatial distribution of the laser spots (scan sequence) during a corneal laser procedure affected the surface quality and maximum ablation depth of the ablation profile. Corneal laser surgery could theoretically benefit from smaller spot sizes and higher repetition rates. The temporal and spatial spot distributions are relevant to achieving these aims.

  8. Laser-induced partial oxidation of cyclohexane in liquid phase

    International Nuclear Information System (INIS)

    Oshima, Y.; Wu, X.W.; Koda, S.

    1995-01-01

    A laser-induced partial oxidation of cyclohexane was studied in the liquid phase. With KrF excimer laser (248 nm) irradiation to neat liquid cyclohexane in which O 2 was dissolved, cyclohexanol and cyclohexanone were obtained with very high selectivities, together with cyclohexane as a minor product. Radical recombination reactions to produce dicyclohexyl ether and bicyclohexyl also took place, while these products were not observed in the gas phase reaction. These experimental results were considered to be due not only to higher concentration of cyclohexane but to the cage effect in the liquid phase oxidation. To clarify the reaction progress including the photoabsorption process, the effects of laser intensity and O 2 pressure on product distribution were studied. (author)

  9. Topography-guided hyperopic and hyperopic astigmatism femtosecond laser-assisted LASIK: long-term experience with the 400 Hz eye-Q excimer platform

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-06-01

    Full Text Available Anastasios John KanellopoulosDepartment of Ophthalmology, New York University Medical School, New York, NY, and LaserVision.gr Eye Institute, Athens, GreeceBackground: The purpose of this study was to evaluate the safety and efficacy of topography-guided ablation using the WaveLight 400 Hz excimer laser in laser-assisted in situ keratomileusis (LASIK for hyperopia and/or hyperopic astigmatism.Methods: We prospectively evaluated 208 consecutive LASIK cases for hyperopia with or without astigmatism using the topography-guided platform of the 400 Hz Eye-Q excimer system. The mean preoperative sphere value was +3.04 ± 1.75 (range 0.75–7.25 diopters (D and the mean cylinder value was –1.24 ± 1.41 (–4.75–0 D. Flaps were created either with Intralase FS60 (AMO, Irvine, CA or FS200 (Alcon, Fort Worth, TX femtosecond lasers. Parameters evaluated included age, preoperative and postoperative refractive error, uncorrected distance visual acuity, corrected distance visual acuity, flap diameter and thickness, topographic changes, higher order aberration changes, and low contrast sensitivity. These measurements were repeated postoperatively at regular intervals for at least 24 months.Results: Two hundred and two eyes were available for follow-up at 24 months. Uncorrected distance visual acuity improved from 5.5/10 to 9.2/10. At 24 (8–37 months, 75.5% of the eyes were in the ±0.50 D range and 94.4% were in the ±1.00 D range of the refractive goal. Postoperatively, the mean sphere value was –0.39 ± 0.3 and the cylinder value was –0.35 ± 0.25. Topographic evidence showed that ablation was made in the visual axis and not in the center of the cornea, thus correlating with the angle kappa. No significant complications were encountered in this small group of patients.Conclusion: Hyperopic LASIK utilizing the topography-guided platform of the 400 Hz Eye-Q Allegretto excimer and a femtosecond laser flap appears to be safe and effective for

  10. Corneal ablation depth readout of the MEL 80 excimer laser compared to Artemis three-dimensional very high-frequency digital ultrasound stromal measurements.

    Science.gov (United States)

    Reinstein, Dan Z; Archer, Timothy J; Gobbe, Marine

    2010-12-01

    To evaluate the accuracy of the ablation depth readout for the MEL 80 excimer laser (Carl Zeiss Meditec). Artemis 1 very high-frequency digital ultrasound measurements were obtained before and at least 3 months after LASIK in 121 eyes (65 patients). The Artemis-measured ablation depth was calculated as the maximum difference in stromal thickness before and after treatment. Laser in situ keratomileusis was performed using the MEL 80 excimer laser and the Hansatome microkeratome (Bausch & Lomb). The Aberration Smart Ablation profile was used in 56 eyes and the Tissue Saving Ablation profile was used in 65 eyes. All ablations were centered on the corneal vertex. Comparative statistics and linear regression analysis were performed between the laser readout ablation depth and Artemis-measured ablation depth. The mean maximum myopic meridian was -6.66±2.40 diopters (D) (range: -1.50 to -10.00 D) for Aberration Smart Ablation-treated eyes and -6.50±2.56 D (range: -1.34 to -11.50 D) for Tissue Saving Ablation-treated eyes. The MEL 80 readout was found to overestimate the Artemis-measured ablation depth by 20±12 μm for Aberration Smart Ablation and by 21±12 μm for Tissue Saving Ablation profiles. The accuracy of ablation depth measurement was improved by using the Artemis stromal thickness profile measurements before and after surgery to exclude epithelial changes. The MEL 80 readout was found to overestimate the achieved ablation depth. The linear regression equations could be used by MEL 80 users to adjust the ablation depth for predicted residual stromal thickness calculations without increasing the risk of ectasia due to excessive keratectomy depth as long as a suitable flap thickness bias is included. Copyright 2010, SLACK Incorporated.

  11. Pulsed Er:YAG- and 308 nm UV-excimer laser: an in vitro and in vivo study of skin-ablative effects

    Energy Technology Data Exchange (ETDEWEB)

    Kaufmann, R.; Hibst, R.

    1989-01-01

    Using a pulsed XeCl excimer laser (308 nm) and a pulsed Er:YAG laser (2,940 nm), we investigated skin ablation as a function of pulse number, radiant energy, and repetition rate. In vitro analysis of lesions performed in freshly excised human skin were consistent with in vivo results obtained from experiments on pig skin. Pulsed 308 nm laser radiation caused considerable nonspecific thermal tissue injury followed by an inflammatory reaction and impaired healing of lesions in vivo. These findings were especially pronounced with higher repetition rates, which would be required for efficient destruction of larger lesions. On the other hand, the 2.94 microns Er:YAG laser radiation produced clean and precise lesions with only minimal adjacent injury. In vivo skin ablation caused intraoperative bleeding with deeper penetration. The Er:YAG laser offers a promising surgical tool for careful removal of superficial epidermal lesions, if higher repetition rates, and an appropriate laser beam delivery system are available for clinical use.

  12. Excimers of organic molecules

    Science.gov (United States)

    Barashkov, Nikolai N.; Sakhno, T. V.; Nurmukhametov, Ravil'N.; Khakhel', O. A.

    1993-06-01

    Studies devoted to excimers in organic systems are surveyed. Processes leading to the excitation of the excimer luminescence are examined. Examples of the excimer-like glow of dimers are described. The relation between the structure of the complexes and their fluorescence properties is demonstrated. The bibliography includes 218 references.

  13. Consistent comparison of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided LASIK for myopia by EX500 excimer laser.

    Science.gov (United States)

    Sun, Ming-Shen; Zhang, Li; Guo, Ning; Song, Yan-Zheng; Zhang, Feng-Ju

    2018-01-01

    To evaluate and compare the uniformity of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided ablation of laser in situ keratomileusis (LASIK) by EX500 excimer laser for myopia. Totally 145 cases (290 consecutive eyes )with myopia received LASIK with a target of emmetropia. The ablation for 86 cases (172 eyes) was guided manually based on Oculyzer topography (study group), while the ablation for 59 cases (118 eyes) was guided automatically by Topolyzer Vario topography (control group). Measurement of adjustment values included data respectively in horizontal and vertical direction of cornea. Horizontally, synclastic adjustment between manually actual values (dx manu ) and Oculyzer topography guided data (dx ocu ) accounts 35.5% in study group, with mean dx manu /dx ocu of 0.78±0.48; while in control group, synclastic adjustment between automatically actual values (dx auto ) and Oculyzer topography data (dx ocu ) accounts 54.2%, with mean dx auto /dx ocu of 0.79±0.66. Vertically, synclastic adjustment between dy manu and dy ocu accounts 55.2% in study group, with mean dy manu /dy ocu of 0.61±0.42; while in control group, synclastic adjustment between dy auto and dy ocu accounts 66.1%, with mean dy auto /dy ocu of 0.66±0.65. There was no statistically significant difference in ratio of actual values/Oculyzer topography guided data in horizontal and vertical direction between two groups ( P =0.951, 0.621). There is high consistency in angle Kappa adjustment guided manually by Oculyzer and guided automatically by Topolyzer Vario topography during corneal refractive surgery by WaveLight EX500 excimer laser.

  14. Laser-induced nuclear fusion

    International Nuclear Information System (INIS)

    Jablon, Claude

    1977-01-01

    Research programs on laser-induced thermonuclear fusion in the United States, in Europe and in USSR are reviewed. The principle of the fusion reactions induced is explained, together with the theoretical effects of the following phenomena: power and type of laser beams, shape and size of the solid target, shock waves, and laser-hydrodynamics coupling problems [fr

  15. Comparison of Placido disc and Scheimpflug image-derived topography-guided excimer laser surface normalization combined with higher fluence CXL: the Athens Protocol, in progressive keratoconus

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2013-07-01

    Full Text Available Anastasios John Kanellopoulos,1,2 George Asimellis11Laservision.gr Eye Institute, Athens, Greece; 2New York University School of Medicine, Department of Opthalmology, NY, NY, USABackground: The purpose of this study was to compare the safety and efficacy of two alternative corneal topography data sources used in topography-guided excimer laser normalization, combined with corneal collagen cross-linking in the management of keratoconus using the Athens protocol, ie, a Placido disc imaging device and a Scheimpflug imaging device.Methods: A total of 181 consecutive patients with keratoconus who underwent the Athens protocol between 2008 and 2011 were studied preoperatively and at months 1, 3, 6, and 12 postoperatively for visual acuity, keratometry, and anterior surface corneal irregularity indices. Two groups were formed, depending on the primary source used for topoguided photoablation, ie, group A (Placido disc and group B (Scheimpflug rotating camera. One-year changes in visual acuity, keratometry, and seven anterior surface corneal irregularity indices were studied in each group.Results: Changes in visual acuity, expressed as the difference between postoperative and preoperative corrected distance visual acuity were +0.12 ± 0.20 (range +0.60 to -0.45 for group A and +0.19 ± 0.20 (range +0.75 to -0.30 for group B. In group A, K1 (flat keratometry changed from 45.202 ± 3.782 D to 43.022 ± 3.819 D, indicating a flattening of -2.18 D, and K2 (steep keratometry changed from 48.670 ± 4.066 D to 45.865 ± 4.794 D, indicating a flattening of -2.805 D. In group B, K1 (flat keratometry changed from 46.213 ± 4.082 D to 43.190 ± 4.398 D, indicating a flattening of -3.023 D, and K2 (steep keratometry changed from 50.774 ± 5.210 D to 46.380 ± 5.006 D, indicating a flattening of -4.394 D. For group A, the index of surface variance decreased to -5.07% and the index of height decentration to -26.81%. In group B, the index of surface variance

  16. F2 excimer laser (157 nm) radiation modification and surface ablation of PHEMA hydrogels and the effects on bioactivity: Surface attachment and proliferation of human corneal epithelial cells

    International Nuclear Information System (INIS)

    Zainuddin; Chirila, Traian V.; Barnard, Zeke; Watson, Gregory S.; Toh, Chiong; Blakey, Idriss; Whittaker, Andrew K.; Hill, David J.T.

    2011-01-01

    Physical and chemical changes at the surface of poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels modified by ablation with an F 2 excimer laser were investigated experimentally. An important observation was that only the outer exposed surface layers of the hydrogel were affected by the exposure to 157 nm radiation. The effect of the surface changes on the tendency of cells to adhere to the PHEMA was also investigated. A 0.5 cm 2 area of the hydrogel surfaces was exposed to laser irradiation at 157 nm to fluences of 0.8 and 4 J cm -2 . The changes in surface topography were analysed by light microscopy and atomic force microscopy, while the surface chemistry was characterized by attenuated total reflection infrared and X-ray photoelectron spectroscopies. Cell-interfacial interactions were examined based on the proliferation of human corneal limbal epithelial (HLE) cells cultured on the laser-modified hydrogels, and on the unexposed hydrogels and tissue culture plastic for comparison. It was observed that the surface topography of laser-exposed hydrogels showed rippled patterns with a surface roughness increasing at the higher exposure dose. The changes in surface chemistry were affected not only by an indirect effect of hydrogen and hydroxyl radicals, formed by water photolysis, on the PHEMA, but also by the direct action of laser radiation on PHEMA if the surface layers of the gel become depleted of water. The laser treatment led to a change in the surface characteristics, with a lower concentration of ester side-chains and the formation of new oxygenated species at the surface. The surface also became more hydrophobic. Most importantly, the surface chemistry and the newly created surface topographical features were able to improve the attachment, spreading and growth of HLE cells.

  17. Visual and refractive outcomes of LASIK with the SCHWIND ESIRIS and WaveLight ALLEGRETTO WAVE Eye-q excimer lasers: a prospective, contralateral study.

    Science.gov (United States)

    Mearza, Ali A; Muhtaseb, Mohammed; Aslanides, Ioannis M

    2008-11-01

    To compare the safety, efficacy, and predictability of LASIK with the SCHWIND ESIRIS and WaveLight ALLEGRETTO WAVE Eye-Q excimer laser platforms. This prospective study comprised 44 eyes of 22 consecutive patients who were treated with LASIK using the Moria M2 microkeratome. One eye was treated with the SCHWIND ESIRIS laser and the fellow eye treated with the WaveLight ALLEGRETTO WAVE Eye-Q laser. All eyes operated with the SCHWIND ESIRIS were treated with standard aspheric ablation, whereas the eyes operated with the WaveLight ALLEGRETTO WAVE Eye-Q received treatment with three different ablation types according to the common practice at our clinic. Outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and proximity to target refraction at 6-month follow-up. At 6 months postoperative, mean decimal UCVA was 0.96+/-0.22 (range: 0.3 to 1.2) for ESIRIS eyes and 0.98+/-0.17 (range: 0.6 to 1.2) for ALLEGRETTO eyes (P=.57). Mean postoperative spherical equivalent refraction was -0.02+/-0.28 diopters (D) (range: -0.75 to +0.75 D) for ESIRIS eyes and 0.11+/-0.91 D (range: -1.00 to +3.88 D) for ALLEGRETTO eyes (P=.49). Of the ESIRIS eyes, 20/22 (91%) were within +/-1.00 D of target refraction and 20/22 (91%) were within +/-0.50 D of target refraction. Of the ALLEGRETTO eyes, 20/22 (91%) and 19/22 (86%) were within +/-1.00 D and +/-0.50 D, respectively, of target refraction. No patient lost > or =2 lines of BSCVA in either group. No differences were seen in safety and efficacy outcome parameters between the SCHWIND ESIRIS and WaveLight ALLEGRETTO WAVE Eye-Q excimer lasers when used according to a previously established treatment algorithm at our clinic in the treatment of refractive error.

  18. Laser Structuring of Thin Layers for Flexible Electronics by a Shock Wave-induced Delamination Process

    Science.gov (United States)

    Lorenz, Pierre; Ehrhardt, Martin; Zimmer, Klaus

    The defect-free laser-assisted structuring of thin films on flexible substrates is a challenge for laser methods. However, solving this problem exhibits an outstanding potential for a pioneering development of flexible electronics. Thereby, the laser-assisted delamination method has a great application potential. At the delamination process: the localized removal of the layer is induced by a shock wave which is produced by a laser ablation process on the rear side of the substrate. In this study, the thin-film patterning process is investigated for different polymer substrates dependent on the material and laser parameters using a KrF excimer laser. The resultant structures were studied by optical microscopy and white light interferometry (WLI). The delamination process was tested at different samples (indium tin oxide (ITO) on polyethylene terephthalate (PET), epoxy-based negative photoresist (SU8) on polyimide (PI) and indium tin oxide/copper indium gallium selenide/molybdenum (ITO/CIGS/Mo) on PI.

  19. The excimer lamp induces cutaneous nerve degeneration and reduces scratching in a dry-skin mouse model.

    Science.gov (United States)

    Kamo, Atsuko; Tominaga, Mitsutoshi; Kamata, Yayoi; Kaneda, Kazuyuki; Ko, Kyi C; Matsuda, Hironori; Kimura, Utako; Ogawa, Hideoki; Takamori, Kenji

    2014-12-01

    Epidermal hyperinnervation, which is thought to underlie intractable pruritus, has been observed in patients with atopic dermatitis (AD). The epidermal expression of axonal guidance molecules has been reported to regulate epidermal hyperinnervation. Previously, we showed that the excimer lamp has antihyperinnervative effects in nonpruritic dry-skin model mice, although epidermal expression of axonal guidance molecules was unchanged. Therefore, we investigated the antipruritic effects of excimer lamp irradiation and its mechanism of action. A single irradiation of AD model mice significantly inhibited itch-related behavior 1 day later, following improvement in the dermatitis score. In addition, irradiation of nerve fibers formed by cultured dorsal root ganglion neurons increased bleb formation and decreased nerve fiber expression of nicotinamide mononucleotide adenylyl transferase 2, suggesting degenerative changes in these fibers. We also analyzed whether attaching a cutoff excimer filter (COF) to the lamp, thus decreasing cytotoxic wavelengths, altered hyperinnervation and the production of cyclobutane pyrimidine dimer (CPD), a DNA damage marker, in dry-skin model mice. Irradiation with COF decreased CPD production in keratinocytes, as well as having an antihyperinnervative effect, indicating that the antipruritic effects of excimer lamp irradiation with COF are due to induction of epidermal nerve degeneration and reduced DNA damage.

  20. Effect of KrF excimer laser irradiation on the surface changes and photoelectric properties of ZnO single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Yong [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Beijing Engineering Research Center of 3D Printing for Digital Medical Health, Beijing International Cooperation Base of 3D Printing for Digital MedicalHealth, Beijing University of Technology, Beijing 100124 (China); Zhao, Yan [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Jiang, Yijian, E-mail: yjjiang@bjut.edu.cn [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Beijing Engineering Research Center of 3D Printing for Digital Medical Health, Beijing International Cooperation Base of 3D Printing for Digital MedicalHealth, Beijing University of Technology, Beijing 100124 (China)

    2016-06-25

    In this paper, the effect of KrF pulsed excimer laser irradiation on the structural, surface morphology, photoluminescence and electrical properties of ZnO single crystal was investigated. Compared to the as-grown sample, at an irradiation energy density of 257 mJ/cm{sup 2}, the ZnO single crystal exhibits a series of phenomenon: XRD and Raman results show that the crystallization of ZnO quality change slightly, resistivity is decreased by two orders of magnitude, carrier concentration is increased by one order of magnitude. After laser irradiation, the surface shows some strip lines and no cracks. Formula calculation and simulation results show that the stripes are not caused by surface melting. We speculate that these stripes are caused by the precipitation of ZnO material inside to the surface. Due to the reduction of oxygen vacancies, UV emission has been enhanced and visible emission has been declined after irradiation. After the laser irradiation, the visible light of ZnO surface can be regulated. The experimental results show that KrF laser irradiation could effectively improve the optical and electrical properties of ZnO single crystal, which is important for the application of high performance of emitting optoelectronic devices. - Highlights: • After laser irradiation, the surface shows some strip lines and no cracks. • The visible light of as-irradiated ZnO surface can be regulated to four colors. • The electrical properties of as-irradiated ZnO has been improved greatly.

  1. O impacto da cirurgia de ceratectomia fotorrefrativa (PRK e ceratomileuse assistida por excimer laser in situ (LASIK na qualidade visual e de vida em pacientes com ametropias The impact of photorefractive excimer laser keratectomy (PRK and laser in situ keratomileusis (LASIK on visual quality and life in patients with ametropias

    Directory of Open Access Journals (Sweden)

    Ricardo Belfort

    2008-02-01

    Full Text Available OBJETIVO: Avaliar a qualidade de vida e de visão e o estresse de pacientes portadores de ametropias submetidos a procedimentos cirúrgicos. MÉTODOS: Estudo longitudinal observacional em que foram estudados 100 pacientes; 54 usuários de óculos, 21 usuários de lentes de contato interessados no procedimento cirúrgico e 25 controles usuários de óculos ou lentes de contato, mas que não desejavam ser operados no período de um ano. Os questionários aplicados foram o National Eye Institute Visual Function Questionnaire (NEI-VFQ-25 de qualidade de vida e o Self Reporting Questionnaire - SRQ-20 para avaliação da saúde mental. Os pacientes que se submeteram à cirurgia responderam aos questionários aplicados por uma observadora antes da mesma, três, seis e doze meses após a intervenção. O grupo controle respondeu de forma auto-aplicada no início do estudo, seis e doze meses após a primeira avaliação. RESULTADOS: No grupo da cirugia dos 54 pacientes que usavam óculos 39 fizeram cirurgia de ceratectomia fotorrefrativa por excimer laser(PRK e 15 fizeram ceratomileuse assistida por excimer laserin situ (LASIK e dos 21 que usavam lentes de contato 12 fizeram cirurgia de ceratectomia fotorrefrativa e nove fizeram ceratomileuse assistida por excimer laser in situ (LASIK. O grupo controle esteve estável durante os 12 meses em relação aos instrumentos aplicados. Três meses após a cirurgia o grupo da cirurgia apresentou melhora significante da qualidade de vida e de visão em relação ao pré-operatório independentemente do tipo de cirurgia realizada. Um ano após a cirurgia os índices de qualidade de vida e de saúde mental, foram semelhantes aos do grupo controle. O Self Reporting Questionnaire - SRQ 20 mostrou diminuição significante do índice de sintomas a partir dos três meses de pós-operatório. CONCLUSÃO: A qualidade de visão e de vida dos pacientes submetidos à cirurgia de correção de ametropia mudou

  2. 准分子激光角膜表层切削术后的止痛措施%Pain control after excimer laser corneal surface ablation

    Institute of Scientific and Technical Information of China (English)

    曾原; 黄一飞; 高建华

    2014-01-01

    准分子激光角膜表层切削术因降低角膜膨隆的风险和避免准分子激光原位角膜磨镶术( LASIK)角膜瓣相关的并发症而受到青睐。但术后严重疼痛不适为表层切削的主要缺陷,因此表层切削术后疼痛不适的控制显得尤其重要。我们总结了表层切削术后疼痛的机制以及降低术后疼痛的措施的进展。%By reshaping the cornea without the creation of a stromal flap, excimer laser corneal surface ablation eliminates flap-related complications and avoids the risk of ectasia that may occur after laser assisted in situ keratomileusis ( LASIK ) . Post-operative pain is one of the most significant disadvantages of surface ablation and thus the management of pain and discomfort following surface ablation is of great importance. We summarize mechanism of corneal pain and current approaches to pain management after surface ablation.

  3. Effect of excimer laser annealing on a-InGaZnO thin-film transistors passivated by solution-processed hybrid passivation layers

    International Nuclear Information System (INIS)

    Bermundo, Juan Paolo; Ishikawa, Yasuaki; Fujii, Mami N; Uraoka, Yukiharu; Nonaka, Toshiaki; Ishihara, Ryoichi; Ikenoue, Hiroshi

    2016-01-01

    We demonstrate the use of excimer laser annealing (ELA) as a low temperature annealing alternative to anneal amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) passivated by a solution-processed hybrid passivation layer. Usually, a-IGZO is annealed using thermal annealing at high temperatures of up to 400 °C. As an alternative to high temperature thermal annealing, two types of ELA, XeCl (308 nm) and KrF (248 nm) ELA, are introduced. Both ELA types enhanced the electrical characteristics of a-IGZO TFTs leading to a mobility improvement of ∼13 cm 2 V −1 s −1 and small threshold voltage which varied from ∼0–3 V. Furthermore, two-dimensional heat simulation using COMSOL Multiphysics was used to identify possible degradation sites, analyse laser heat localization, and confirm that the substrate temperature is below 50 °C. The two-dimensional heat simulation showed that the substrate temperature remained at very low temperatures, less than 30 °C, during ELA. This implies that any flexible material can be used as the substrate. These results demonstrate the large potential of ELA as a low temperature annealing alternative for already-passivated a-IGZO TFTs. (paper)

  4. Effect of excimer laser annealing on a-InGaZnO thin-film transistors passivated by solution-processed hybrid passivation layers

    Science.gov (United States)

    Bermundo, Juan Paolo; Ishikawa, Yasuaki; Fujii, Mami N.; Nonaka, Toshiaki; Ishihara, Ryoichi; Ikenoue, Hiroshi; Uraoka, Yukiharu

    2016-01-01

    We demonstrate the use of excimer laser annealing (ELA) as a low temperature annealing alternative to anneal amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) passivated by a solution-processed hybrid passivation layer. Usually, a-IGZO is annealed using thermal annealing at high temperatures of up to 400 °C. As an alternative to high temperature thermal annealing, two types of ELA, XeCl (308 nm) and KrF (248 nm) ELA, are introduced. Both ELA types enhanced the electrical characteristics of a-IGZO TFTs leading to a mobility improvement of ~13 cm2 V-1 s-1 and small threshold voltage which varied from ~0-3 V. Furthermore, two-dimensional heat simulation using COMSOL Multiphysics was used to identify possible degradation sites, analyse laser heat localization, and confirm that the substrate temperature is below 50 °C. The two-dimensional heat simulation showed that the substrate temperature remained at very low temperatures, less than 30 °C, during ELA. This implies that any flexible material can be used as the substrate. These results demonstrate the large potential of ELA as a low temperature annealing alternative for already-passivated a-IGZO TFTs.

  5. Necessary conditions for the homogeneous formation of a volume avalanche discharge with specific applications to rare gas-halide excimer laser discharges

    International Nuclear Information System (INIS)

    Levatter, J.I.

    1979-01-01

    Self-sustained/avalanche discharges are an efficient method of rare gas-halide excimer laser excitation in small systems. However, with the exceptions of the work reported here, experiments attempting to increase the laser energy output by scaling up the discharge volume and/or pulse duration have not been successful. The major problem encountered in scaling experiments has been the formation of arc channels in the discharge volume. The presence of arcing can totally disrupt proper laser operation. This problem stems from a general lack of understanding of high pressure avalanche discharge phenomena. Therefore, clarifying the basic discharge formation process and establishing a set of criteria under which a homogeneous avalanche discharge can be obtained is of central importance in defining the scaling limits of avalanche discharge lasers. The work presented here reviews the phenomena involved in high E/n (electric field to gas number density ratio) breakdown and its relationship to the formation of spatially homogeneous discharges. This relationship was first explored by A.J. Palmer in 1974. The basic requirement of his model was that the preionization density be large enough to cause an appreciable overlap of the primary electron avalanches and hence smooth out the ensuing space-charge fields to the extent that individual streamer formation would be prevented. This is the same basic model used in the more detailed discharge formation analysis developed here except that the effects of a time varying electric field caused by a finite voltage rise time and the effects due to the various electrochemical properties of the gas mixture are property taken into consideration

  6. Effect of basic fibroblast growth factor and cytochrome c peroxidase combination in transgenic mice corneal epithelial healing process after excimer laser photoablation

    Directory of Open Access Journals (Sweden)

    Sergio Zaccaria Scalinci

    2011-02-01

    Full Text Available Sergio Zaccaria Scalinci1, Lucia Scorolli1, Alessandro Meduri2, Pier Luigi Grenga3, Giulia Corradetti1, Cristian Metrangolo11Low Vision Center – University of Bologna, Bologna, Italy; 2Department of Surgical Specialities, Ophthalmology Clinic, University of Messina, Messina, Italy; 3Department of Ophthalmology, University of Rome "La Sapienza", Rome, ItalyPurpose: To evaluate the role of prepared basic fibroblast growth factor (bFGF and cytochrome c peroxidase (CCP combination eyedrops in corneal epithelial healing of transgenic mice (B6(A-Rperd12/J after excimer laser photoablation. Materials and methods: In this prospective study, 216 eyes of 108 mice underwent bilateral photorefractive keratectomy. We considered 4 groups: A, B, C, and D. Group A received standard topical postoperative therapy with tobramycin, diclofenac, and dexamethasone eyedrops plus CCP at 3 drops per day for a week or until corneal re-epithelialization was achieved. Group B received standard topical postoperative therapy plus bFGF eyedrops and phosphate-buffered saline (PBS 3 drops per day for a week or until corneal re-epithelialization was complete. In group C, 1 eye received standard topical postoperative therapy plus CCP eyedrops, bFGF eyedrops, and PBS 3 drops per day for a week or until corneal re-epithelialization was complete. Control eyes (group D received a standard topical postoperative therapy plus placebo eyedrops. Mice were followed-up for a week from the day after the surgery to evaluate the rate of corneal re-epithelialization.Results: Data were analyzed by ANOVA using the XLSTAT 2010 software. Eyes in group A, B, and C healed completely before the fifth postoperative day, achieving, respectively, a re-epithelialization time of 92 hours ± 10 SD, 90 hours ± 12 SD, and 86 hours ± 12 SD. Group D had a re-epithelialization time of 121 hours ± 8 SD (P < 0.05. No side effects or toxic effects were documented.Conclusions: Results suggest that re

  7. Laser induced pyrolysis techniques

    International Nuclear Information System (INIS)

    Vanderborgh, N.E.

    1976-01-01

    The application of laser pyrolysis techniques to the problems of chemical analysis is discussed. The processes occurring during laser pyrolysis are first briefly reviewed. The problems encountered in laser pyrolysis gas chromatography are discussed using the analysis of phenanthrene and binary hydrocarbons. The application of this technique to the characterization of naturally occurring carbonaceous material such as oil shales and coal is illustrated

  8. Comparison of Immediate and 2-Year Outcomes between Excimer Laser-Assisted Angioplasty with Spot Stent and Primary Stenting in Intermediate to Long Femoropopliteal Disease

    Directory of Open Access Journals (Sweden)

    Tien-Yu Wu

    2013-01-01

    Full Text Available Background. To compare the clinical outcomes between excimer laser-assisted angioplasty (ELA with spot stent (group A and primary stenting (group B in intermediate to long femoropopliteal disease. Methods. Outcomes of 105 patients totaling 119 legs treated with two different strategies were analyzed retrospectively in a prospectively maintained database. Results. Baseline characteristics were similar in both groups. Better angiographic results and lesser increase of serum C-reactive protein levels (0.60 ± 0.72 versus 2.98 ± 0.97 mg/dL, P<0.001 after the intervention were obtained in Group B. Group A had inferior 1-year outcomes due to higher rate of binary restenosis (67% versus 32%, P=0.001 and lower rate of primary patency (40% versus 58%, P=0.039. Rates of amputation-free survival, target vessel revascularization, assisted primary patency, and stent fracture at 24 months were similar in both groups (80% versus 82%, P=0.979, 65% versus 45%, P=0.11, 78% versus 80%, P=0.75 and 6.3% versus 6.8%, P=0.71, resp.. Conclusion. Greater vascular inflammation after ELA with spot stent resulted in earlier restenosis and inferior 1-year clinical outcomes than primary stenting. This benefit was lost in the primary stenting group at 2 years due to late catch-up restenosis. Active surveillance with prompt intervention was required to maintain the vessel patency.

  9. Cool excimer laser-assisted angioplasty (CELA) and tibial balloon angioplasty (TBA) in management of infragenicular arterial occlusion in critical lower limb ischemia (CLI).

    Science.gov (United States)

    Sultan, Sherif; Tawfick, Wael; Hynes, Niamh

    2013-04-01

    We aim to compare cool excimer laser-assisted angioplasty (CELA) versus tibial balloon angioplasty (TBA) in patients with critical limb ischemia (CLI) with tibial artery occlusive disease. The primary end point is sustained clinical improvement (SCI) and amputation-free survival (AFS). The secondary end points are binary restenosis, target extremity revascularization (TER), and cost-effectiveness. From June 2005 to October 2010, 1506 patients were referred with peripheral vascular disease and 572 with CLI. A total of 80 patients underwent 89 endovascular revascularizations (EVRs) for tibial occlusions, 47 using TBA and 42 using CELA. All patients were Rutherford category 4 to 6. Three-year SCI was enhanced with CELA (81%) compared to TBA (63.8%; P = .013). Three-year AFS significantly improved with CELA (95.2%) versus TBA (89.4%; P = .0165). Three-year freedom from TER was significantly improved with CELA (92.9%) versus 78.7% TBA (P = .026). Three-year freedom from MACE was comparable in both the groups (P = .455). Patients with CELA had significantly improved quality time without symptoms of disease or toxicity of treatment (Q-TWiST) at 3 years (10.5 months; P = .048) with incremental cost of €2073.19 per quality-adjusted life year gained. Tibial EVR provides exceptional outcome in CLI. The CELA has superior SCI, AFS, and freedom from TER, with improved Q-TWiST and cost-effectiveness.

  10. Differences in optical coherence tomographic findings and clinical outcomes between excimer laser and cutting balloon angioplasty for focal in-stent restenosis lesions.

    Science.gov (United States)

    Nishino, Masami; Lee, Yasuharu; Nakamura, Daisuke; Yoshimura, Takahiro; Taniike, Masayuki; Makino, Nobuhiko; Kato, Hiroyasu; Egami, Yasuyuki; Shutta, Ryu; Tanouchi, Jun; Yamada, Yoshio

    2012-10-01

    In-stent restenosis (ISR), especially focal ISR, after percutaneous coronary intervention (PCI) remains one of the major clinical problems in the drug-eluting stent (DES) era. Several reports have revealed that excimer laser coronary angioplasty (ELCA) is useful for ISR; however, detailed findings after ELCA are unknown. Therefore, we investigated the condition of the neointima after ELCA for ISR with optical coherence tomography (OCT) and compared the OCT findings and clinical outcome between ELCA and cutting-balloon angioplasty (CBA). Twenty-one consecutive patients with focal ISR who underwent ELCA or CBA were enrolled. All patients underwent 12- to 15-month follow-up coronary angiography. OCT was performed immediately after successful PCI to evaluate the neointimal condition in the ISR lesion. We compared the following OCT parameters between ELCA and CBA groups: maximal thickness of remaining in-stent neointima (MTN), number of tears, minimum lumen dimension (MLD), and minimum lumen area (MLA). We also evaluated clinical outcomes, including target vessel revascularization, acute myocardial infarction, death, and stent thrombosis. MLA in the ELCA group (n = 10) was significantly larger than in the CBA group, and number of tears in the ELCA group was significantly lower than in the CBA group. A trend was shown toward lower TLR with ELCA versus CBA (10.0% vs 45.5%). OCT immediately after ELCA for ISR lesions revealed larger lumen area and smaller number of tears compared with CBA, which may support favorable effects of ELCA for focal ISR.

  11. Nano-crystallization in ZnO-doped In{sub 2}O{sub 3} thin films via excimer laser annealing for thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Mami N., E-mail: f-mami@ms.naist.jp; Ishikawa, Yasuaki; Bermundo, Juan Paolo Soria; Uraoka, Yukiharu [Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Ishihara, Ryoichi; Cingel, Johan van der; Mofrad, Mohammad R. T. [Delft University of Technology, Feldmannweg 17, P.O. Box 5053, 2600 GB Delft (Netherlands); Kawashima, Emi; Tomai, Shigekazu; Yano, Koki [Idemitsu Kosan Co., Ltd., 1280 Kami-izumi, Sodegaura, Chiba, 299-0293 (Japan)

    2016-06-15

    In a previous work, we reported the high field effect mobility of ZnO-doped In{sub 2}O{sub 3} (IZO) thin film transistors (TFTs) irradiated by excimer laser annealing (ELA) [M. Fujii et al., Appl. Phys. Lett. 102, 122107 (2013)]. However, a deeper understanding of the effect of ELA on the IZO film characteristics based on crystallinity, carrier concentrations, and optical properties is needed to control localized carrier concentrations for fabricating self-aligned structures in the same oxide film and to adequately explain the physical characteristics. In the case of as-deposited IZO film used as the channel, a high carrier concentration due to a high density of oxygen vacancies was observed; such a film does not show the required TFT characteristics but can act as a conductive film. We achieved a decrease in the carrier concentration of IZO films by crystallization using ELA. This means that ELA can form localized conductive or semi-conductive areas on the IZO film. We confirmed that the reason for the carrier concentration decrease was the decrease of oxygen-deficient regions and film crystallization. The annealed IZO films showed nano-crystalline phase, and the temperature at the substrate was substantially less than the temperature limit for flexible films such as plastic, which is 50°C. This paves the way for the formation of self-aligned structures and separately formed conductive and semi-conductive regions in the same oxide film.

  12. Nano-crystallization in ZnO-doped In_2O_3 thin films via excimer laser annealing for thin-film transistors

    International Nuclear Information System (INIS)

    Fujii, Mami N.; Ishikawa, Yasuaki; Bermundo, Juan Paolo Soria; Uraoka, Yukiharu; Ishihara, Ryoichi; Cingel, Johan van der; Mofrad, Mohammad R. T.; Kawashima, Emi; Tomai, Shigekazu; Yano, Koki

    2016-01-01

    In a previous work, we reported the high field effect mobility of ZnO-doped In_2O_3 (IZO) thin film transistors (TFTs) irradiated by excimer laser annealing (ELA) [M. Fujii et al., Appl. Phys. Lett. 102, 122107 (2013)]. However, a deeper understanding of the effect of ELA on the IZO film characteristics based on crystallinity, carrier concentrations, and optical properties is needed to control localized carrier concentrations for fabricating self-aligned structures in the same oxide film and to adequately explain the physical characteristics. In the case of as-deposited IZO film used as the channel, a high carrier concentration due to a high density of oxygen vacancies was observed; such a film does not show the required TFT characteristics but can act as a conductive film. We achieved a decrease in the carrier concentration of IZO films by crystallization using ELA. This means that ELA can form localized conductive or semi-conductive areas on the IZO film. We confirmed that the reason for the carrier concentration decrease was the decrease of oxygen-deficient regions and film crystallization. The annealed IZO films showed nano-crystalline phase, and the temperature at the substrate was substantially less than the temperature limit for flexible films such as plastic, which is 50°C. This paves the way for the formation of self-aligned structures and separately formed conductive and semi-conductive regions in the same oxide film.

  13. Remarkable enhancement on elimination reaction of side groups in excimer laser ablation of mixture targets of perylene derivatives with metal powder

    International Nuclear Information System (INIS)

    Nishio, Satoru; Tamura, Kazuyuki; Tsujine, Yukari; Fukao, Tomoko; Nakano, Masayoshi; Matsuzaki, Akiyoshi; Sato, Hiroyasu

    2002-01-01

    Films are deposited on substrates at 20 deg.C by excimer laser ablation (ELA) of mixture targets of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with metal powder, PTCDA/M (M=Co, Ni, Fe, W, Cu and Ag) using XeCl and ArF beams. Large amount of fragments with ''naked'' perylene skeletons can be produced owing to effective elimination of carboxylic dianhydride groups by ELA of PTCDA/Co both with XeCl and ArF beams under optimized ablation conditions. Elimination reaction of side groups of PTCDA is observed for ELA of the targets with metal powder of the iron group, Co, Fe and Ni, especially remarkable for Co and Fe. The film from PTCDA/Ni consists of small particles with the various diameters ranging from 10 to 100 nm as well as that from PTCDA/Co. Morphology like petal of rose can be seen everywhere for the film from PTCDA/Fe

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

    Indian Academy of Sciences (India)

    The study of excimer and van der Waals molecules such as Hg2, Cd2 and Zn2 are of current interest as they are potential candidates for the possible development of new high power excimer lasers. Group IIB metal dimers (Hg2, Cd2 and Zn2) have essentially repulsive ground states with very shallow van der Walls minima.

  15. Preparation of the La0.8Sr0.2MnO3 films on STO and LAO substrates by excimer laser-assisted metal organic deposition using the KrF laser

    International Nuclear Information System (INIS)

    Tsuchiya, T.; Daoudi, K.; Manabe, T.; Yamaguchi, I.; Kumagai, T.

    2007-01-01

    La 0.8 Sr 0.2 MnO 3 films were prepared on SrTiO 3 (STO) and LaAlO 3 (LAO) substrates using excimer laser-assisted metal organic deposition (ELAMOD). For the LAO substrate, no epitaxial La 0.8 Sr 0.2 MnO 3 film was obtained by laser irradiation in the fluence range from 60 to 110 mJ/cm 2 with heating at 500 deg. C. On the other hand, an epitaxial La 0.8 Sr 0.2 MnO 3 film on the STO substrate was formed by laser irradiation in the fluence range from 60 to 100 mJ/cm 2 with heating at 500 deg. C. To optimize the electrical properties for an IR sensor, the effects of the laser fluence, the irradiation time and the film thickness on the temperature dependence of the resistance and temperature coefficient of resistance (TCR: defined as 1/R.(dR/dT)) of the LSMO films were investigated. An LSMO film on the STO substrate that showed the maximum TCR of 3.9% at 265 K was obtained by the ELAMOD process using the KrF laser

  16. Ultrafast switching in wetting properties of TiO2/YSZ/Si(001) epitaxial heterostructures induced by laser irradiation

    International Nuclear Information System (INIS)

    Bayati, M. R.; Molaei, R.; Narayan, J.; Joshi, S.; Narayan, R. J.

    2013-01-01

    We have demonstrated dark hydrophilicity of single crystalline rutile TiO 2 (100) thin films, in which rapid switching from a hydrophobic to a hydrophilic surface was achieved using nanosecond excimer laser irradiation. The TiO 2 /YSZ/Si(001) single crystalline heterostructures were grown by pulsed laser deposition and were subsequently irradiated by a single pulse of a KrF excimer laser at several energies. The wettability of water on the surfaces of the samples was evaluated. The samples were hydrophobic prior to laser annealing and turned hydrophilic after laser annealing. Superhydrophilic surfaces were obtained at higher laser energy densities (e.g., 0.32 J.cm −2 ). The stoichiometries of the surface regions of the samples before and after laser annealing were examined using XPS. The results revealed the formation of oxygen vacancies on the surface, which are surmised to be responsible for the observed superhydrophilic behavior. According to the AFM images, surface smoothening was greater in films that were annealed at higher laser energy densities. The samples exhibited hydrophobic behavior after being placed in ambient atmosphere. The origin of laser induced wetting behavior was qualitatively understood to stem from an increase of point defects near the surface, which lowered the film/water interfacial energy. This type of rapid hydrophobic/hydrophilic switching may be used to facilitate fabrication of electronic and photonic devices with novel properties.

  17. Arthroscopic cartilage debridement by excimer laser in chondromalacia of the knee joint. A prospective randomized clinical study.

    Science.gov (United States)

    Raunest, J; Löhnert, J

    1990-01-01

    A new operative technique in arthroscopic treatment of chondromalacia using ultraviolet laser systems is introduced. The postoperative results are evaluated in a prospective and randomized clinical trial. One hundred and forty patients stage II or III chondromalacia according to Outerbridge were randomly assigned to arthroscopic operation using either laser or mechanical instruments. After a 6-month follow-up period the clinical results were compared, guided by a specially designed modification of the Lysholm scoring scale. In the short-term follow-up laser surgery gave superior results in regard to reducing pain (P less than 0.05) and leading to a lower incidence of reactive synovitis (P less than 0.01). No difference was found in respect of disability and functional impairment. Our results lead to the conclusion that arthroscopic laser application seems to be a successful procedure in the treatment of degenerative cartilage disorders, providing precise ablation of tissue without significant thermal damage to the remaining cartilage.

  18. Surface analysis of the selective excimer laser patterning of a thin PEDOT:PSS film on flexible polymer films

    Science.gov (United States)

    Schaubroeck, David; De Smet, Jelle; Willems, Wouter; Cools, Pieter; De Geyter, Nathalie; Morent, Rino; De Smet, Herbert; Van Steenbeerge, Geert

    2016-07-01

    Fast patterning of highly conductive polymers like PEDOT:PSS (poly (3,4-ethylene dioxythiophene): polystyrene sulfonate) with lasers can contribute to the development of industrial production of liquid crystal displays on polymer foils. In this article, the selective UV laser patterning of a PEDOT:PSS film on flexible polymer films is investigated. Based on their optical properties, three polymer films are investigated: polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) and cellulose triacetate (TAC). Ablation parameters for a 110 nm PEDOT:PSS film on these polymer films are optimized. A detailed study of the crater depth, topography and surface composition are provided using optical profilometry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The electrical insulation of the lines is measured and correlated to the crater analyses for different laser settings. Finally, potential ablation parameters for each of the polymer films are derived.

  19. SBS pulse compression for excimer inertial fusion energy drivers

    Energy Technology Data Exchange (ETDEWEB)

    Linford, G.J. [TRW Space and Electronics Group, Redondo Beach, CA (United States). Space and Technology Div.

    1994-12-31

    A key requirement for the development of commercial fusion power plants utilizing inertial confinement fusion (ICF) as a source of thermonuclear power is the availability of reliable, efficient laser drivers. These laser drivers must be capable of delivering UV optical pulses having energies of the order of 5MJ to cryogenic deuterium-tritium (D/T) ICF targets. The current requirements for laser ICF target irradiation specify the laser wavelength, {lambda} ca. 250 nm, pulse duration, {tau}{sub p} ca. 6 ns, bandwidth, {Delta}{lambda} ca. 0.1 nm, polarization state, etc. Excimer lasers are a leading candidate to fill these demanding ICF driver requirements. However, since excimer lasers are not storage lasers, the excimer laser pulse duration, {tau}{sub pp}, is determined primarily by the length of the excitation pulse delivered to the excimer laser amplifier. Pulsed power associated with efficiently generating excimer laser pulses has a time constant, {tau}{sub pp} which falls in the range, 30 {tau}{sub p}<{tau}{sub pp}<100{tau}{sub p}. As a consequence, pulse compression is needed to convert the long excimer laser pulses to pulses of duration {tau}{sub p}. These main ICF driver pulses require, in addition, longer, lower power precursor pulses delivered to the ICF target before the arrival of the main pulse. Although both linear and non-linear optical (NLO) pulse compression techniques have been developed, computer simulations have shown that a ``chirped,`` self-seeded, stimulated Brillouin scattering (SBS) pulse compressor cell using SF{sub 6} at a density, {rho} ca. 1 amagat can efficiently compress krypton fluoride (KrF) laser pulses at {lambda}=248 nm. In order to avoid the generation of output pulses substantially shorter than {tau}{sub p}, the optical power in the chirped input SBS ``seed`` beams was ramped. Compressed pulse conversion efficiencies of up to 68% were calculated for output pulse durations of {tau}{sub p} ca. ns.

  20. SBS pulse compression for excimer inertial fusion energy drivers

    International Nuclear Information System (INIS)

    Linford, G.J.

    1994-01-01

    A key requirement for the development of commercial fusion power plants utilizing inertial confinement fusion (ICF) as a source of thermonuclear power is the availability of reliable, efficient laser drivers. These laser drivers must be capable of delivering UV optical pulses having energies of the order of 5MJ to cryogenic deuterium-tritium (D/T) ICF targets. The current requirements for laser ICF target irradiation specify the laser wavelength, λ ca. 250 nm, pulse duration, τ p ca. 6 ns, bandwidth, Δλ ca. 0.1 nm, polarization state, etc. Excimer lasers are a leading candidate to fill these demanding ICF driver requirements. However, since excimer lasers are not storage lasers, the excimer laser pulse duration, τ pp , is determined primarily by the length of the excitation pulse delivered to the excimer laser amplifier. Pulsed power associated with efficiently generating excimer laser pulses has a time constant, τ pp which falls in the range, 30 τ p pp p . As a consequence, pulse compression is needed to convert the long excimer laser pulses to pulses of duration τ p . These main ICF driver pulses require, in addition, longer, lower power precursor pulses delivered to the ICF target before the arrival of the main pulse. Although both linear and non-linear optical (NLO) pulse compression techniques have been developed, computer simulations have shown that a ''chirped,'' self-seeded, stimulated Brillouin scattering (SBS) pulse compressor cell using SF 6 at a density, ρ ca. 1 amagat can efficiently compress krypton fluoride (KrF) laser pulses at λ=248 nm. In order to avoid the generation of output pulses substantially shorter than τ p , the optical power in the chirped input SBS ''seed'' beams was ramped. Compressed pulse conversion efficiencies of up to 68% were calculated for output pulse durations of τ p ca. ns

  1. Surface analysis of the selective excimer laser patterning of a thin PEDOT:PSS film on flexible polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Schaubroeck, David, E-mail: David.Schaubroeck@elis.ugent.be [Center for Microsystems Technology (CMST), imec and Ghent University, Technologiepark 15, B-9052 Ghent (Belgium); De Smet, Jelle; Willems, Wouter [Center for Microsystems Technology (CMST), imec and Ghent University, Technologiepark 15, B-9052 Ghent (Belgium); Cools, Pieter; De Geyter, Nathalie; Morent, Rino [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); De Smet, Herbert; Van Steenbeerge, Geert [Center for Microsystems Technology (CMST), imec and Ghent University, Technologiepark 15, B-9052 Ghent (Belgium)

    2016-07-15

    Highlights: • Laser patterning of thin film PEDOT:PSS on polymer foils is characterized in great detail. • PEDOT:PSS does not need to be fully removed to create electrically insulating patterns. • The underlying polymer foil influences the ablation behavior. - Abstract: Fast patterning of highly conductive polymers like PEDOT:PSS (poly (3,4-ethylene dioxythiophene): polystyrene sulfonate) with lasers can contribute to the development of industrial production of liquid crystal displays on polymer foils. In this article, the selective UV laser patterning of a PEDOT:PSS film on flexible polymer films is investigated. Based on their optical properties, three polymer films are investigated: polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) and cellulose triacetate (TAC). Ablation parameters for a 110 nm PEDOT:PSS film on these polymer films are optimized. A detailed study of the crater depth, topography and surface composition are provided using optical profilometry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The electrical insulation of the lines is measured and correlated to the crater analyses for different laser settings. Finally, potential ablation parameters for each of the polymer films are derived.

  2. SITE - EMERGING TECHNOLOGIES: LASER INDUCED PHOTO- CHEMICAL OXIDATIVE DESTRUCTION OF TOXIC ORGANICS IN LEACHATES AND GROUNDWATERS

    Science.gov (United States)

    The technology described in this report has been developed under the Emerging Technology Program of the Superfund Innovative Technology Evaluation (SITE) Program to photochemically oxidize organic compounds in wastewater by applying ultraviolet radiation using an excimer laser. T...

  3. Surface ablation with iris recognition and dynamic rotational eye tracking-based tissue saving treatment with the Technolas 217z excimer laser.

    Science.gov (United States)

    Prakash, Gaurav; Agarwal, Amar; Kumar, Dhivya Ashok; Jacob, Soosan; Agarwal, Athiya; Maity, Amrita

    2011-03-01

    To evaluate the visual and refractive outcomes and expected benefits of Tissue Saving Treatment algorithm-guided surface ablation with iris recognition and dynamic rotational eye tracking. This prospective, interventional case series comprised 122 eyes (70 patients). Pre- and postoperative assessment included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, and higher order aberrations. All patients underwent Tissue Saving Treatment algorithm-guided surface ablation with iris recognition and dynamic rotational eye tracking using the Technolas 217z 100-Hz excimer platform (Technolas Perfect Vision GmbH). Follow-up was performed up to 6 months postoperatively. Theoretical benefit analysis was performed to evaluate the algorithm's outcomes compared to others. Preoperative spherocylindrical power was sphere -3.62 ± 1.60 diopters (D) (range: 0 to -6.75 D), cylinder -1.15 ± 1.00 D (range: 0 to -3.50 D), and spherical equivalent -4.19 ± 1.60 D (range: -7.75 to -2.00 D). At 6 months, 91% (111/122) of eyes were within ± 0.50 D of attempted correction. Postoperative UDVA was comparable to preoperative CDVA at 1 month (P=.47) and progressively improved at 6 months (P=.004). Two eyes lost one line of CDVA at 6 months. Theoretical benefit analysis revealed that of 101 eyes with astigmatism, 29 would have had cyclotorsion-induced astigmatism of ≥ 10% if iris recognition and dynamic rotational eye tracking were not used. Furthermore, the mean percentage decrease in maximum depth of ablation by using the Tissue Saving Treatment was 11.8 ± 2.9% over Aspheric, 17.8 ± 6.2% over Personalized, and 18.2 ± 2.8% over Planoscan algorithms. Tissue saving surface ablation with iris recognition and dynamic rotational eye tracking was safe and effective in this series of eyes. Copyright 2011, SLACK Incorporated.

  4. Evaluation of intraocular pressure according to corneal thickness before and after excimer laser corneal ablation for myopia.

    Science.gov (United States)

    Hamed-Azzam, Shirin; Briscoe, Daniel; Tomkins, Oren; Shehedeh-Mashor, Raneen; Garzozi, Hanna

    2013-08-01

    Intraocular pressure is affected by corneal thickness and biomechanics. Following ablative corneal refractive surgery, corneal structural changes occur. The purpose of the study is to determine the relationship between the mean central corneal thickness (CCT) and the change in intraocular pressure measurements following various corneal ablation techniques, using different measurement methods. Two hundred myopic eyes undergoing laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) were enrolled into a prospective, non-randomized study. Corneal parameters examined included full ocular examination, measurement of CCT, corneal topography, corneal curvature and ocular refractivity. Intraocular pressure measurements were obtained using three different instruments-non-contact tonometer, Goldmann applanation tonometer and TonoPen XL (TonoPen-Central and TonoPen-Peripheral). All measurements were performed pre-operatively and 4 months post-operatively. Post-operative intraocular pressure was significantly lower than pre-operative values, with all instruments (p value tonometer and non-contact tonometer (p value < 0.001, ANOVA). Intraocular pressure readings are significantly reduced following corneal ablation surgery. We determined in our myopic patient cohort that the TonoPen XL intraocular pressure measurement method is the least affected following PRK and LASIK as compared to other techniques.

  5. Contralateral comparison of wavefront-guided LASIK surgery with iris recognition versus without iris recognition using the MEL80 Excimer laser system.

    Science.gov (United States)

    Wu, Fang; Yang, Yabo; Dougherty, Paul J

    2009-05-01

    To compare outcomes in wavefront-guided LASIK performed with iris recognition software versus without iris recognition software in different eyes of the same patient. A randomised, prospective study of 104 myopic eyes of 52 patients undergoing LASIK surgery with the MEL80 excimer laser system was performed. Iris recognition software was used in one eye of each patient (study group) and not used in the other eye (control group). Higher order aberrations (HOAs), contrast sensitivity, uncorrected vision (UCV), visual acuity (VA) and corneal topography were measured and recorded pre-operatively and at one month and three months post-operatively for each eye. The mean post-operative sphere and cylinder between groups was similar, however the post-operative angles of error (AE) by refraction were significantly smaller in the study group compared to the control group both in arithmetic and absolute means (p = 0.03, p = 0.01). The mean logMAR UCV was significantly better in the study group than in the control group at one month (p = 0.01). The mean logMAR VA was significantly better in the study group than in control group at both one and three months (p = 0.01, p = 0.03). In addition, mean trefoil, total third-order aberration, total fourth-order aberration and the total scotopic root-mean-square (RMS) HOAs were significantly less in the study group than those in the control group at the third (p = 0.01, p = 0.05, p = 0.04, p = 0.02). By three months, the contrast sensitivity had recovered in both groups but the study group performed better at 2.6, 4.2 and 6.6 cpd (cycles per degree) than the control group (p = 0.01, p iris recognition results in better VA, lower mean higher-order aberrations, lower refractive post-operative angles of error and better contrast sensitivity at three months post-operatively than LASIK performed without iris recognition.

  6. Laser induced fusion - theoretical aspects

    International Nuclear Information System (INIS)

    Lawande, S.V.; Gunye, M.R.

    1979-01-01

    The theoretical aspects of thermonuclear fusion induced by laser are discussed. After outlining the basic features and the energetics of laser fusion in the chapter 1, various non-linear mechanisms responsible for an enhanced absorption of laser energy into the plasma and the stimulated scattering processes which hinder the absorption are discussed in the second chapter on laser plasma interactions. The third chapter on gas dynamics and the shock phenomena presents the mathematical formulation of the compression to high densities of the core of the pellet for its implosion. A hydrodynamic model developed to stimulate the evolution of laser heated symmetric plasma is outlined in the chapter four on numerichigly relativistic noninteracting particles, regular bouncing states may occur at high densities, or at high temperatures. The latter case is considered in details for the collapse phase of a hot universe; lepton pair creation may completely decelerate the collapse of a hot hadronic plasma, provided the observational parameters, the Hubble constant Hsub(deg), the matter parameter Ωsub(deg) and the deceleration parameter qsub(deg) satisfy certain constraint conditions

  7. Laser-induced multiphoton transitions

    International Nuclear Information System (INIS)

    Stenholm, S.

    1978-06-01

    Laser induced multiphoton processes are reviewed. The effects of strong fields on atoms are discussed. The perturbation treatment is presented and also its generalization to treat intermediate resonances. The influence of atomic coherence is discussed heuristically and the relation between quantal and classical descriptions of the field is elucidated by reference to the dressed atom description. Atomic ionization experiments are reviewed and the present understanding of multiphoton dissociation of molecules is explained. Finally some prospects for the future are discussed. (author)

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

    International Nuclear Information System (INIS)

    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

  9. Comparación de la medición del grosor corneal central medido con el paquímetro incluido en el Wavelight® Ex500 Excimer Laser y el tomógrafo de cámara de Scheimpflug Pentacam® en sujetos sanos

    Directory of Open Access Journals (Sweden)

    Manuel Garza León

    2017-01-01

    Conclusiones: Nuestros resultados demuestran que el paquímetro incluido en el Wavelight® Ex500 Excimer Laser es una buena alternativa para la medición del grosor corneal central al Pentacam® en pacientes sanos.

  10. Chromatin damage induced by fast neutrons or UV laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Radu, L.; Constantinescu, B.; Gazdaru, D.; Mihailescu, I

    2002-07-01

    Chromatin samples from livers of Wistar rats were subjected to fast neutron irradiation in doses of 10-100 Gy or to a 248 nm excimer laser radiation, in doses of 0.5-3 MJ.m{sup -2}. The action of the radiation on chromatin was monitored by chromatin intrinsic fluorescence and fluorescence lifetimes (of bound ethidium bromide to chromatin) and by analysing fluorescence resonance energy transfer between dansyl chloride and acridine orange coupled to chromatin. For the mentioned doses of UV excimer laser radiation, the action on chromatin was more intense than in the case of fast neutrons. The same types of damage are produced by the two radiations: acidic and basic destruction of chromatin protein structure, DNA strand breaking and the increase of the distance between DNA and proteins in chromatin. (author)

  11. Chromatin damage induced by fast neutrons or UV laser radiation

    International Nuclear Information System (INIS)

    Radu, L.; Constantinescu, B.; Gazdaru, D.; Mihailescu, I.

    2002-01-01

    Chromatin samples from livers of Wistar rats were subjected to fast neutron irradiation in doses of 10-100 Gy or to a 248 nm excimer laser radiation, in doses of 0.5-3 MJ.m -2 . The action of the radiation on chromatin was monitored by chromatin intrinsic fluorescence and fluorescence lifetimes (of bound ethidium bromide to chromatin) and by analysing fluorescence resonance energy transfer between dansyl chloride and acridine orange coupled to chromatin. For the mentioned doses of UV excimer laser radiation, the action on chromatin was more intense than in the case of fast neutrons. The same types of damage are produced by the two radiations: acidic and basic destruction of chromatin protein structure, DNA strand breaking and the increase of the distance between DNA and proteins in chromatin. (author)

  12. From small aromatic molecules to functional nanostructured carbon by pulsed laser-induced photochemical stitching

    Directory of Open Access Journals (Sweden)

    R. R. Gokhale

    2012-06-01

    Full Text Available A novel route employing UV laser pulses (KrF Excimer, 248 nm to cleave small aromatic molecules and stitch the generated free radicals into functional nanostructured forms of carbon is introduced. The process differs distinctly from any strategies wherein the aromatic rings are broken in the primary process. It is demonstrated that this pulsed laser-induced photochemical stitching (PLPS process when applied to routine laboratory solvents (or toxic chemical wastes when discarded Chlorobenzene and o-Dichlorobenzene yields Carbon Nanospheres (CNSs comprising of graphene-like sheets assembled in onion-like configurations. This room temperature process implemented under normal laboratory conditions is versatile and clearly applicable to the whole family of haloaromatic compounds without and with additions of precursors or other nanomaterials. We further bring out its applicability for synthesis of metal-oxide based carbon nanocomposites.

  13. Lasers '89

    International Nuclear Information System (INIS)

    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

  14. Laser-induced damage in optical materials

    CERN Document Server

    Ristau, Detlev

    2014-01-01

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

  15. Numerical studies of temperature profile and hydrodynamic phenomena during excimer laser assisted heteroepitaxial growth of patterned silicon and germanium bi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati Roma (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-01-01

    In this manuscript, a 3-D axisymmetric model for the heteroepitaxial growth induced by irradiating thin patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers on Si (100) with pulsed UV-laser radiation, is presented. For reducing optimization steps, an efficient simulation of the laser induced processes that include rapid heating and solidification phenomena in the range of several tenth of nanoseconds, must be performed, if alloy composition and quality has to be adjusted. In this study, the effects of various laser energy densities on different amorphous Si/Ge bi-layer structures has been predicted and adjusted to obtain the desired Ge concentration profiles for applications as sacrificial layers, i.e. a Ge containing film buried under a Si rich surface layer. The numerical model includes the temperature dependent variations of the thermophysical properties and takes the coupled effects of temperature and hydrodynamic phenomena for a Boussinesq fluid, to estimate the element interdiffusion during the process and predicting the concentration profiles.

  16. Instantaneous imaging of ozone in a gliding arc discharge using photofragmentation laser-induced fluorescence

    Science.gov (United States)

    Larsson, Kajsa; Hot, Dina; Gao, Jinlong; Kong, Chengdong; Li, Zhongshan; Aldén, Marcus; Bood, Joakim; Ehn, Andreas

    2018-04-01

    Ozone vapor, O3, is here visualized in a gliding arc discharge using photofragmentation laser-induced fluorescence. Ozone is imaged by first photodissociating the O3 molecule into an O radical and a vibrationally hot O2 fragment by a pump photon. Thereafter, the vibrationally excited O2 molecule absorbs a second (probe) photon that further transits the O2-molecule to an excited electronic state, and hence, fluorescence from the deexcitation process in the molecule can be detected. Both the photodissociation and excitation processes are achieved within one 248 nm KrF excimer laser pulse that is formed into a laser sheet and the fluorescence is imaged using an intensified CCD camera. The laser-induced signal in the vicinity of the plasma column formed by the gliding arc is confirmed to stem from O3 rather than plasma produced vibrationally hot O2. While both these products can be produced in plasmas a second laser pulse at 266 nm was utilized to separate the pump- from the probe-processes. Such arrangement allowed lifetime studies of vibrationally hot O2, which under these conditions were several orders of magnitude shorter than the lifetime of plasma-produced ozone.

  17. Femtosecond laser-induced herringbone patterns

    Science.gov (United States)

    Garcell, Erik M.; Lam, Billy; Guo, Chunlei

    2018-06-01

    Femtosecond laser-induced herringbone patterns are formed on copper (Cu). These novel periodic structures are created following s-polarized, large incident angle, femtosecond laser pulses. Forming as slanted and axially symmetric laser-induced periodic surface structures along the side walls of ablated channels, the result is a series of v-shaped structures that resemble a herringbone pattern. Fluence mapping, incident angle studies, as well as polarization studies have been conducted and provide a clear understanding of this new structure.

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

    CSIR Research Space (South Africa)

    Labuschagne, K

    2005-07-01

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

  19. Infrared laser-induced chemical reactions

    International Nuclear Information System (INIS)

    Katayama, Mikio

    1978-01-01

    The experimental means which clearly distinguishes between infrared ray-induced reactions and thermal reactions has been furnished for the first time when an intense monochromatic light source has been obtained by the development of infrared laser. Consequently, infrared laser-induced chemical reactions have started to develop as one field of chemical reaction researches. Researches of laser-induced chemical reactions have become new means for the researches of chemical reactions since they were highlighted as a new promising technique for isotope separation. Specifically, since the success has been reported in 235 U separation using laser in 1974, comparison of this method with conventional separation techniques from the economic point of view has been conducted, and it was estimated by some people that the laser isotope separation is cheaper. This report briefly describes on the excitation of oscillation and reaction rate, and introduces the chemical reactions induced by CW laser and TEA CO 2 laser. Dependence of reaction yield on laser power, measurement of the absorbed quantity of infrared ray and excitation mechanism are explained. Next, isomerizing reactions are reported, and finally, isotope separation is explained. It was found that infrared laser-induced chemical reactions have the selectivity for isotopes. Since it is evident that there are many examples different from thermal and photo-chemical reactions, future collection of the data is expected. (Wakatsuki, Y.)

  20. Laser induced white lighting of tungsten filament

    Science.gov (United States)

    Strek, W.; Tomala, R.; Lukaszewicz, M.

    2018-04-01

    The sustained bright white light emission of thin tungsten filament was induced under irradiation with focused beam of CW infrared laser diode. The broadband emission centered at 600 nm has demonstrated the threshold behavior on excitation power. Its intensity increased non-linearly with excitation power. The emission occurred only from the spot of focused beam of excitation laser diode. The white lighting was accompanied by efficient photocurrent flow and photoelectron emission which both increased non-linearly with laser irradiation power.

  1. Laser induced densification of cerium gadolinium oxide: Application to single-chamber solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mariño, Mariana [École Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR 5307, LGF, F-42023 Saint-Étienne (France); Rieu, Mathilde, E-mail: rieu@emse.fr [École Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR 5307, LGF, F-42023 Saint-Étienne (France); Viricelle, Jean-Paul [École Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR 5307, LGF, F-42023 Saint-Étienne (France); Garrelie, Florence [Université Jean Monnet, Laboratoire Hubert Curien, CNRS: UMR 5516, 42000 Saint-Etienne (France)

    2016-06-30

    Graphical abstract: - Highlights: • CGO surface densifications were induced by UV and IR laser irradiations. • Grain growth or densified cracked surfaces were observed by SEM. • UV laser treatments allow a decrease of gas permeation through electrolyte layer. • Electrical conductivity of the electrolyte was modified by laser treatments. • Grain growth of electrolyte induced by UV laser improved cell performances. - Abstract: In single-chamber solid oxide fuel cells (SC-SOFC), anode and cathode are placed in a gas chamber where they are exposed to a fuel/air mixture. Similarly to conventional dual-chamber SOFC, the anode and the cathode are separated by an electrolyte. However, as in the SC-SOFC configuration the electrolyte does not play tightness role between compartments, this one can be a porous layer. Nevertheless, it is necessary to have a diffusion barrier to prevent the transportation of hydrogen produced locally at the anode to the cathode that reduces fuel cell performances. This study aims to obtain directly a diffusion barrier through the surface densification of the electrolyte Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (CGO) by a laser treatment. KrF excimer laser and Yb fiber laser irradiations were used at different fluences and number of pulses to modify the density of the electrolyte coating. Microstructural characterizations confirmed the modifications on the surface of the electrolyte for appropriate experimental conditions showing either grain growth or densified but cracked surfaces. Gas permeation and electrical conductivities of the modified electrolyte were evaluated. Finally SC-SOFC performances were improved for the cells presenting grain growth at the electrolyte surface.

  2. Shock-Assisted Superficial Hexagonal-to-Cubic Phase Transition in GaN/Sapphire Interface Induced by Using Ultra-violet Laser Lift-Of Techniques

    International Nuclear Information System (INIS)

    Wei-Hua, Chen; Xiao-Dong, Hu; Xiang-Ning, Kang; Xu-Rong, Zhou; Xiao-Min, Zhang; Tong-Jun, Yu; Zhi-Jian, Yang; Ke, Xu; Guo-Yi, Zhang; Xu-Dong, Shan; Li-Ping, You

    2009-01-01

    Ultra-violet (KrF excimer laser, λ = 248 nm) laser lift-of (LLO) techniques have been operated to the GaN/sapphire structure to separate GaN from the sapphire substrate. Hexagonal to cubic phase transformation induced by the ultra-violet laser lift-of (UV-LLO) has been characterized by micro-Raman spectroscopy, micro-photoluminescence, along with high-resolution transmission electron microscopy (HRTEM). HRTEM indicates that UV-LLO induced phase transition takes place above the LLO interface, without phase transition under the LLO interface. The formed cubic GaN often exists as nanocrystal grains attaching on the bulk hexagonal GaN. The half-loop-cluster-like UV-LLO interface indicates that the LLO-induced shock waves has generated and played an assistant role in the decomposition of the hexagonal GaN and in the formation of cubic GaN grains at the LLO surface

  3. Electromagnetically induced transparency with broadband laser pulses

    International Nuclear Information System (INIS)

    Yavuz, D. D.

    2007-01-01

    We suggest a scheme to slow and stop broadband laser pulses inside an atomic medium using electromagnetically induced transparency. Extending the suggestion of Harris et al. [Phys. Rev. Lett. 70, 552 (1993)], the key idea is to use matched Fourier components for the probe and coupling laser beams

  4. Nanosecond laser-induced back side wet etching of fused silica with a copper-based absorber liquid

    Science.gov (United States)

    Lorenz, Pierre; Zehnder, Sarah; Ehrhardt, Martin; Frost, Frank; Zimmer, Klaus; Schwaller, Patrick

    2014-03-01

    Cost-efficient machining of dielectric surfaces with high-precision and low-roughness for industrial applications is still challenging if using laser-patterning processes. Laser induced back side wet etching (LIBWE) using UV laser pulses with liquid heavy metals or aromatic hydrocarbons as absorber allows the fabrication of well-defined, nm precise, free-form surfaces with low surface roughness, e.g., needed for optical applications. The copper-sulphatebased absorber CuSO4/K-Na-Tartrate/NaOH/formaldehyde in water is used for laser-induced deposition of copper. If this absorber can also be used as precursor for laser-induced ablation, promising industrial applications combining surface structuring and deposition within the same setup could be possible. The etching results applying a KrF excimer (248 nm, 25 ns) and a Nd:YAG (1064 nm, 20 ns) laser are compared. The topography of the etched surfaces were analyzed by scanning electron microscopy (SEM), white light interferometry (WLI) as well as laser scanning microscopy (LSM). The chemical composition of the irradiated surface was studied by energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR). For the discussion of the etching mechanism the laser-induced heating was simulated with finite element method (FEM). The results indicate that the UV and IR radiation allows micro structuring of fused silica with the copper-based absorber where the etching process can be explained by the laser-induced formation of a copper-based absorber layer.

  5. Improvement of corrosion resistance of carbon steel using chemical vapor deposition from Cr(CO)6 and Mo(CO)6 with an ArF-excimer laser

    International Nuclear Information System (INIS)

    Okada, Naotada; Katsumura, Yosuke; Ishigure, Kenkichi

    1995-01-01

    The corrosion resistance of carbon steel has been improved by the deposition from the mixture of Mo(CO) 6 and Cr(CO) 6 as well as from each carbonyl alone with an ArF-excimer (193nm). The corrosion resistance evaluated by multi sweep cyclic voltammetry attained by coating with the films from the mixture is higher than from Mo(CO) 6 alone, while lower than from Cr(CO) 6 alone. While the corrosion resistance increases with beam intensity monotonically over the range 4-25 MWcm -2 for the deposition from Mo(CO) 6 alone, it tends to decrease slightly above 15 MWcm -2 for the deposition from Mo(CO) 6 alone and from the mixture. SEM photographs show that the films from each carbonyl and their mixture consist of small grains that are more densely packed at higher beam intensities. The comparison of the film thickness evaluated from sputtering time to remove the films with that from direct observation with SEM suggests that the density of the film increases with beam intensity. In the films deposited from the mixture, molybdenum is preferentially incorporated from the gas phase. In addition, a model of gas-phase processes including photolysis of Cr(CO) 6 , transportation of photofragments to the substrate surface, and elimination of photofragments through chemical reactions during transportation, is proposed and simulated. Applications of the model will be discussed. (author)

  6. Excimer UV curing in printing

    International Nuclear Information System (INIS)

    Mehnert, R.

    1999-01-01

    It is the aim of this study to investigate the potential of 308 run excimer UV curing in web and sheet fed offset printing and to discuss its present status. Using real-time FTIR-ATR and stationary or pulsed monochromatic (313 nm) irradiation chemical and physical factors affecting the curing speed of printing inks such as nature and concentration of photo-initiators, reactivity of the ink binding system, ink thickness and pigmentation, irradiance in the curing plane, oxygen concentration and nitrogen inerting, multiple pulse exposure, the photochemical dark reaction and temperature dependence were studied. The results were used to select optimum conditions for excimer UV curing in respect to ink reactivity, nitrogen inerting and UV exposure and to build an excimer UV curing unit consisting of two 50 W/cm 308 run excimer lamps, power supply, cooling and inerting unit. The excimer UV curing devices were tested under realistic conditions on a web offset press zirkon supra forte and a sheet fed press Heidelberg GTO 52. Maximum curing speeds of 300 m/min in web offset and 8000 sheets per hour in sheet fed offset were obtained

  7. Laser induced nuclear orientation effects

    International Nuclear Information System (INIS)

    Burns, M.; Pappas, P.; Feld, M.S.; Murnick, D.E.

    1977-01-01

    Resonant laser radiation can orient metastable nuclei, resulting in spatially anisotropic emission of β or γ radiation. This technique can be used to obtain isomer shifts and nuclear moments and can lead to isomer separation. (Auth.)

  8. Field enhancement induced laser ablation

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    Sub-diffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures....... The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron and atomic force microscopy. Thickness...

  9. The development of a laser-induced photoacoustic facility for actinide speciation

    International Nuclear Information System (INIS)

    Ewart, F.T.; McMillan, J.W.; Pollard, P.M.; Thomason, H.P.; Liezers, M.

    1987-09-01

    A laser induced photoacoustic spectroscopy (LIPAS) facility has been developed at Harwell to measure actinide species in solution with the minimal disturbance of the species equilibria. The novel true dual beam system, which is based on an excimer laser driven dye laser and optical cells mounted on piezoelectric detectors, has high sensitivity and stability, and is capable of detecting Am(III) at ca 10 -8 M and Np(IV), (V) and (VI) at ca 10 -7 M. Samples can be measured in an inert atmosphere glove box which helps to maintain the anaerobic conditions expected in deep waste repositories. To date, LIPAS has been used to measure actinide species directly in solutions from waste programmes and to observe americium and neptunium species in solutions of varying Eh, pH and carbonate concentration. The information gained is being used to validate the data used in the geochemical/thermodynamic codes used to predict possible radionuclide species within a radioactive waste repository. (author)

  10. The development of a laser-induced photoacoustic facility for actinide speciation

    International Nuclear Information System (INIS)

    Ewart, F.T.; McMillan, J.W.; Thomason, H.P.; Liezers, M.; Pollard, P.M.

    1988-02-01

    A laser induced photoacoustic spectroscopy (LIPAS) facility has been developed at Harwell to measure actinide species in solution with the minimal disturbance of the species equilibria. The novel true dual beam system, which is based on an excimer laser driven dye laser and optical cells mounted on piezoelectric detectors, has high sensitivity and stability, and is capable of detecting Am(III) at ca 10 -8 M and Np(IV), (V) and (VI) at ca 10 -7 M. Samples can be measured in an inert atmosphere glove box which helps to maintain the anaerobic conditions expected in deep waste repositories. To date, LIPAS has been used to measure actinide species directly in solutions from waste programmes and to observe americium and neptunium species in solutions of varying Eh, pH and carbonate concentration. The information gained is being used to validate the data used in the geochemical/thermodynamic codes used to predict possible radionuclide species within a radioactive waste repository. (author)

  11. Heat pump processes induced by laser radiation

    Science.gov (United States)

    Garbuny, M.; Henningsen, T.

    1980-01-01

    A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

  12. Induced Current Characteristics Due to Laser Induced Plasma and Its Application to Laser Processing Monitoring

    International Nuclear Information System (INIS)

    Madjid, Syahrun Nur; Idris, Nasrullah; Kurniawan, Koo Hendrik; Kagawa, Kiichiro

    2011-01-01

    In laser processing, suitable conditions for laser and gas play important role in ensuring a high quality of processing. To determine suitable conditions, we employed the electromagnetic phenomena associated with laser plasma generation. An electrode circuit was utilised to detect induced current due to the fast electrons propelled from the material during laser material processing. The characteristics of induced current were examined by changing parameters such as supplied voltage, laser pulse energy, number of laser shots, and type of ambient gas. These characteristics were compared with the optical emission characteristics. It was shown that the induced current technique proposed in this study is much more sensitive than the optical method in monitoring laser processing, that is to determine the precise focusing condition, and to accurately determine the moment of completion of laser beam penetration. In this study it was also shown that the induced current technique induced by CW CO 2 laser can be applied in industrial material processing for monitoring the penetration completion in a stainless steel plate drilling process.

  13. Hg{sup 2+}-induced self-assembly of a naphthalimide derivative by selective 'turn-on' monomer/excimer emissions

    Energy Technology Data Exchange (ETDEWEB)

    Wanichacheva, Nantanit, E-mail: wanichacheva.nantanit@gmail.com [Department of Chemistry, Faculty of Science, Silpakorn University, Nakorn Pathom 73000 (Thailand); Prapawattanapol, Narupon [Petrochemistry and Polymer Science Program, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Sanghiran Lee, Vannajan [Department of Chemistry, Faculty of Science, University of Malaya 50603, Kuala Lumpur (Malaysia); Grudpan, Kate [Department of Chemistry, Center for Innovation in Chemistry, Faculty of Science, and Center of Excellence in Innovation for Analytical Science and Technology, Chiang Mai 50200 (Thailand); Petsom, Amorn [Research Centre for Bioorganic Chemistry, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

    2013-02-15

    A novel fluorescent sensor bearing two naphthalimide fluorophores based on 2-(3-(2-aminoethylsulfanyl)propylsulfanyl)ethanamine, 1, was readily synthesized for the recognition of Hg{sup 2+}. The sensitive and selective binding behaviors of 1 were investigated by fluorescence spectroscopy. Sensor 1 selectively binds Hg{sup 2+} by exhibiting OFF-ON fluorescence enhancement behaviors of the monomer and excimer bands. The sensor provides excellent Hg{sup 2+}-selectivity in the presence of high concentrations of competitive ions, particularly Cu{sup 2+} and Pb{sup 2+} as well as Na{sup +}, K{sup +}, Mn{sup 2+}, Cd{sup 2+}, Ni{sup 2+}, Ca{sup 2+}, Li{sup +}, Zn{sup 2+} and Co{sup 2+}, with an available detection limit of 2.1 Multiplication-Sign 10{sup -7} M or 42 ppb. - Highlights: Black-Right-Pointing-Pointer Multidentate sulfide-containing ligand bounded to naphthalimide as new Hg{sup 2+} sensor. Black-Right-Pointing-Pointer Sensor is prepared by a straightforward two-step synthesis. Black-Right-Pointing-Pointer Sensor shows high sensitivity and selectivity to Hg{sup 2+} with detection limit of 42 ppb. Black-Right-Pointing-Pointer Hg{sup 2+}-binding is indicated by fluorescence enhancement Black-Right-Pointing-Pointer Sensor 'turns-on' both monomeric and excimer emissions by the addition of Hg{sup 2+}.

  14. Laser-induced mass spectrometry

    International Nuclear Information System (INIS)

    Polanyi, J.C.

    1981-01-01

    This invention provides a method for the spectroscopic analysis of gas. The gas molecules are internally excited by irradiation with laser light having a wavelength which is absorbed by the sample. The gas is then ionized and passed through a mass spectrometer and the amount of the ionized species in the irradiated and ionized sample is compared with that in a similar ionized but not irradiated sample

  15. Excimer PRK testing in the clinic

    Science.gov (United States)

    Forrest, Gary T.

    1994-06-01

    Testing of the excimer lasers used in PRK requires special considerations in terms of ease of use, day-to-day reliability, and high resolution to see details of beam interference effects. SensorPhysics employs a patented photochromic material on a polyester substrate to record permanent, instant records of the laser and laser system output. Since each SensorCard is used only once concerns about detection device deterioration are not an issue. The SensorCards have a demonstrated resolving power on the order of 0.1 micrometers . A small, portable reading device is used to convert the SensorCard optical density to a mJ/cm2 value. Special software also measures beam uniformity to +/- 1% to provide both qualitative and quantitative analysis. Results of use in clinic environments will be presented. In particular detection of exposure `islands' will be demonstrated. The techniques employed are similar to those we developed for UV laser micromachining and lithography four years ago.

  16. Laser induced forward transfer of graphene

    NARCIS (Netherlands)

    Smits, E.C.P.; Walter, A.; Leeuw, D.M. de; Asadi, K.

    2017-01-01

    Transfer of graphene and other two-dimensional materials is still a technical challenge. The 2D-materials are typically patterned after transfer, which leads to a major loss of material. Here, we present laser induced forward transfer of chemical vapor deposition grown graphene layers with

  17. Effect of laser spot size on energy balance in laser induced plasmas

    International Nuclear Information System (INIS)

    Pant, H.C.; Sharma, S.; Bhawalkar, D.D.

    1980-01-01

    The effect of the laser spot size on laser light absorption in laser induced plasmas from solid targets was studied. It was found that at a constant laser intensity on the target, reduction in the laser spot size enhances the net laser energy absorption. It was also observed that the laser light reflection from the target becomes more diffused when the focal spot size is reduced

  18. Instantaneous three-dimensional visualization of concentration distributions in turbulent flows with crossed-plane laser-induced fluorescence imaging

    Science.gov (United States)

    Hoffmann, A.; Zimmermann, F.; Scharr, H.; Krömker, S.; Schulz, C.

    2005-01-01

    A laser-based technique for measuring instantaneous three-dimensional species concentration distributions in turbulent flows is presented. The laser beam from a single laser is formed into two crossed light sheets that illuminate the area of interest. The laser-induced fluorescence (LIF) signal emitted from excited species within both planes is detected with a single camera via a mirror arrangement. Image processing enables the reconstruction of the three-dimensional data set in close proximity to the cutting line of the two light sheets. Three-dimensional intensity gradients are computed and compared to the two-dimensional projections obtained from the two directly observed planes. Volume visualization by digital image processing gives unique insight into the three-dimensional structures within the turbulent processes. We apply this technique to measurements of toluene-LIF in a turbulent, non-reactive mixing process of toluene and air and to hydroxyl (OH) LIF in a turbulent methane-air flame upon excitation at 248 nm with a tunable KrF excimer laser.

  19. Laser-induced nuclear physics and applications

    International Nuclear Information System (INIS)

    Ledingham, K.W.D.; Singhal, R.P.; McKenna, P.; Spencer, I.

    2002-01-01

    With a 1 ps pulse laser at 1 μm wavelength, He gas is ionised at about 3.10 14 W.cm -2 . As the intensity increases, the inert gases become multiple ionised and between 10 18 and 10 19 W.cm -2 photon induced nuclear reactions are energetically possible. Close to 10 21 W.cm -2 pion production can take place. At the very high intensities of 10 28 W.cm -2 , it can be shown that electron-positron pairs can be created from the vacuum. The authors review the applications of high intensity focused laser beams in particle acceleration, laser-induced fission and laser production of protons and neutrons. Exciting new phenomena are expected at intensities higher than 10 22 W.cm -2 , -) the oscillating electric field can affect directly the protons in exactly the same way as the electrons in the plasma, -) fusion reactions by direct laser acceleration of ions. (A.C.)

  20. Laser-Induced Photofragmentation Fluorescence Imaging of Alkali Compounds in Flames.

    Science.gov (United States)

    Leffler, Tomas; Brackmann, Christian; Aldén, Marcus; Li, Zhongshan

    2017-06-01

    Laser-induced photofragmentation fluorescence has been investigated for the imaging of alkali compounds in premixed laminar methane-air flames. An ArF excimer laser, providing pulses of wavelength 193 nm, was used to photodissociate KCl, KOH, and NaCl molecules in the post-flame region and fluorescence from the excited atomic alkali fragment was detected. Fluorescence emission spectra showed distinct lines of the alkali atoms allowing for efficient background filtering. Temperature data from Rayleigh scattering measurements together with simulations of potassium chemistry presented in literature allowed for conclusions on the relative contributions of potassium species KOH and KCl to the detected signal. Experimental approaches for separate measurements of these components are discussed. Signal power dependence and calculated fractions of dissociated molecules indicate the saturation of the photolysis process, independent on absorption cross-section, under the experimental conditions. Quantitative KCl concentrations up to 30 parts per million (ppm) were evaluated from the fluorescence data and showed good agreement with results from ultraviolet absorption measurements. Detection limits for KCl photofragmentation fluorescence imaging of 0.5 and 1.0 ppm were determined for averaged and single-shot data, respectively. Moreover, simultaneous imaging of KCl and NaCl was demonstrated using a stereoscope with filters. The results indicate that the photofragmentation method can be employed for detailed studies of alkali chemistry in laboratory flames for validation of chemical kinetic mechanisms crucial for efficient biomass fuel utilization.

  1. Seven year follow-up after advanced surface ablation with excimer laser for treatment of myopia: Long-term outcomes of cooling PRK and LASEK

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob

    Purpose: To evaluate and compare refractive predictability, uncorrected and corrected distance visual acuity (UDVA and CDVA), corneal haze, corneal densitometry and patient satisfaction up to 7 years after Photorefractive Keratectomy with cooling (cPRK) and Laser-Assisted Sub-epithelial Keratectomy...... (LASEK) for all degrees of myopia, but in particular high myopia. Setting: Department of Ophthalmology, Odense University Hospital, Odense, Denmark. Methods: Retrospective follow-up study of eyes treated with cPRK or LASEK for all degrees of myopia from 2007 to 2009 at the Department of Ophthalmology...... laser with eye-tracker (Carl Zeiss Meditec AG, Jena, Germany) was used for photoablation in both procedures. Optical zone size ranged from 5.50 to 6.00 mm in both procedures, and maximum attempted spherical correction was -8.50 D. cPRK was performed as a standard PRK procedure, but with immediately...

  2. Laser induced fluorescence of trapped molecular ions

    International Nuclear Information System (INIS)

    Grieman, F.J.

    1979-10-01

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

  3. Laser induced fluorescence of trapped molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Grieman, F.J.

    1979-10-01

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

  4. Laser induced forward transfer of soft materials

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  5. Laser induced fluorescence of some plant leaves

    International Nuclear Information System (INIS)

    Helmi, M.S.; Mohamed, M.M.; Amer, R.; Elshazly, O.; Elraey, M.

    1992-01-01

    Laser induced fluorescence (LIF) is successfully used as a technique for remote detection of spectral characteristics of some plants. A pulsed nitrogen laser at 337.1 nm is used to excite cotton, corn and rice leaves. The fluorescence spectrum is detected in the range from 340 nm to 820 nm. It is found that, these plant leaves have common fluorescence maxima at 440 nm, 685 nm and 740 nm. plant leaves are also found to be identifiable by the ratio of the fluorescence intensity at 440 nm to that at 685 nm. The present technique can be further used as a means of assessing, remotely, plant stresses. 5 fig

  6. Self-Induced Faraday Instability Laser

    Science.gov (United States)

    Perego, A. M.; Smirnov, S. V.; Staliunas, K.; Churkin, D. V.; Wabnitz, S.

    2018-05-01

    We predict the onset of self-induced parametric or Faraday instabilities in a laser, spontaneously caused by the presence of pump depletion, which leads to a periodic gain landscape for light propagating in the cavity. As a result of the instability, continuous wave oscillation becomes unstable even in the normal dispersion regime of the cavity, and a periodic train of pulses with ultrahigh repetition rate is generated. Application to the case of Raman fiber lasers is described, in good quantitative agreement between our conceptual analysis and numerical modeling.

  7. Seven year follow-up after advanced surface ablation with excimer laser for treatment of myopia: Long-term outcomes of cooling PRK and LASEK.

    OpenAIRE

    Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob; Vestergaard, Anders Højslet

    2014-01-01

    Purpose: To evaluate and compare refractive predictability, uncorrected and corrected distance visual acuity (UDVA and CDVA), corneal haze, corneal densitometry and patient satisfaction up to 7 years after Photorefractive Keratectomy with cooling (cPRK) and Laser-Assisted Sub-epithelial Keratectomy (LASEK) for all degrees of myopia, but in particular high myopia. Setting: Department of Ophthalmology, Odense University Hospital, Odense, Denmark. Methods: Retrospective follow-up study of eyes t...

  8. DNA damages induced by Ar F laser

    Energy Technology Data Exchange (ETDEWEB)

    Chapel, C.; Rose, S.; Chevrier, L.; Cordier, E.; Courant, D. [CEA Fontenay-aux-Roses, 92 (France). Dept. de Radiobiologie et de Radiopathologie

    2006-07-01

    The photo ablation process used in corneal refractive surgery by the Argon Fluoride (Ar F) laser emitting in ultraviolet C at 193 nm, exposes viable cells round the irradiated zone to sub ablative doses (< 400 joules.m -2). Despite that DNA absorption is higher at 193 nm than 254 nm, cytotoxicity of 193 nm laser radiation is lower than radiation emitted by 254 nm UV-C lamps. In situ, DNA could be protected of laser radiation by cellular components. Consequently, some authors consider that this radiation does not induce genotoxic effect whereas others suspect it to be mutagenic. These lasers are used for fifteen years but many questions remain concerning the long term effects on adjacent cells to irradiated area. The purpose of this study is to describe the effect of 193 nm laser radiation on DNA of stromal keratocytes which are responsible of the corneal structure. The 193 nm laser irradiation induces directly DNA breakage in keratocytes as it has been shown by the comet assay under alkaline conditions. Two hours post irradiation, damages caused by the highest exposure (150 J.m-2) are not repaired as it has been measured with the Olive Tail Moment (product of tail length and tail DNA content). They give partly evidence of induction of an apoptotic process in cells where DNA could be too damaged. In order to characterize specifically double strand breaks, a comparative analysis by immunofluorescence of the H2 Ax histone phosphorylation (H2 Ax) has been performed on irradiated keratocytes and unirradiated keratocytes. Results show a dose dependent increase of the number of H2 Ax positive cells. Consequences of unrepaired DNA lesions could be observed by the generation of micronuclei in cells. Results show again an increase of micronuclei in laser irradiated cells. Chromosomal aberrations have been pointed out by cytogenetic methods 30 mn after irradiation. These aberrations are dose dependent (from 10 to 150 J.m-2). The number of breakage decreases in the long run

  9. Experimental and numerical investigations of a hydrogen-assisted laser-induced materials transfer procedure

    International Nuclear Information System (INIS)

    Toet, D.; Smith, P. M.; Sigmon, T. W.; Thompson, M. O.

    2000-01-01

    We present investigations of the mechanisms of a laser-induced transfer technique, which can be used for the spatially selective deposition of materials such as Si. This transfer is effected by irradiating the backside of a hydrogenated amorphous silicon film, deposited on a transparent substrate with an excimer laser pulse. The resulting release and accumulation of hydrogen at the film/substrate interface propels the silicon onto an adjacent receptor wafer. Time-resolved infrared transmission measurements indicate that the amorphous film is melted by the laser pulse and breaks into droplets during ejection. These droplets travel towards the receptor substrate and coalesce upon arrival. The transfer velocity increases as a function of fluence, the rate of increase dropping noticeably around the full melt threshold of the film. At this fluence, the transfer velocity reaches values of around 1000 m/s for typical films. Atomic force microscopy reveals that films transferred below the full melt threshold only partially cover the receptor substrate, while uniform, well-adhering films, which can be smoothed by subsequent laser irradiation, are obtained above it. Transfer of hydrogen-free Si films, on the other hand, does not occur until much higher fluences. The dynamics of the process have been simulated using a semiquantitative numerical model. In this model, hydrogen released from the melt front is instantaneously accumulated at the interface with an initial kinetic energy given by the melting temperature of Si and the enthalpy of solution. The resulting pressure accelerates the Si film, the dynamics of which are modeled using Newtonian mechanics, and the gas cools adiabatically as its kinetic energy is converted to the film's momentum. The results of the calculations are in good agreement with the experimental data. (c) 2000 American Institute of Physics

  10. Effects of excimer laser irradiation on the expression of Th17, Treg, TGF-beta1, and IL-6 in patients with psoriasis vulgaris

    Science.gov (United States)

    Xiong, Guo-Xin; Li, Xin-Zhong

    2017-11-01

    The effects of laser irradiation on the expression of T helper 17 (Th17) and regulatory T (Treg) cells and their related cytokines, transforming growth factor beta 1 (TGF-β1) and interleukin-6 (IL-6), respectively, in the peripheral blood of patients with psoriasis vulgaris were investigated. 38 patients with psoriasis vulgaris in the stable state were selected as the treatment group that was treated twice a week for eight weeks. Another 38 healthy persons were chosen as the control group. Before and after treatment, the percentages of Th17 cells and Treg cells in the patients’ peripheral blood were detected using flow cytometry, the content of TGF-β1 and IL-6 in the patients’ sera were detected using enzyme-linked immunosorbent assay, and the extent and severity of lesions were determined by weighing the psoriasis area and severity index (PASI). After laser treatment, the percentage of Th17 cells, the Th17/Treg cell ratio and the level of IL-6 in the peripheral blood of patients with psoriasis in the treatment group were significantly lower than those of the same patients before the treatment (P  psoriasis vulgaris was 84.21%, and the PASI score was significantly lower (P  psoriasis vulgaris.

  11. Laser induced fluorescence of trapped molecular ions

    International Nuclear Information System (INIS)

    Winn, J.S.

    1980-10-01

    Laser induced fluoresence (LIF) spectra (laser excitation spectra) are conceptually among the most simple spectra to obtain. One need only confine a gaseous sample in a suitable container, direct a laser along one axis of the container, and monitor the sample's fluorescence at a right angle to the laser beam. As the laser wavelength is changed, the changes in fluorescence intensity map the absorption spectrum of the sample. (More precisely, only absorption to states which have a significant radiative decay component are monitored.) For ion spectroscopy, one could benefit in many ways by such an experiment. Most optical ion spectra have been observed by emission techniques, and, aside from the problems of spectral analysis, discharge emission methods often produce the spectra of many species, some of which may be unknown or uncertain. Implicit in the description of LIF given above is certainty as to the chemical identity of the carrier of the spectrum. This article describes a method by which the simplifying aspects of LIF can be extended to molecular ions

  12. Laser induced fluorescence spectroscopy for FTU

    International Nuclear Information System (INIS)

    Hughes, T.P.

    1995-07-01

    Laser induced fluorescence spectroscopy (LIFS) is based on the absorption of a short pulse of tuned laser light by a group of atoms and the observation of the resulting fluorescence radiation from the excited state. Because the excitation is resonant it is very efficient, and the fluorescence can be many times brighter than the normal spontaneous emission, so low number densities of the selected atoms can be detected and measured. Good spatial resolution can be achieved by using a narrow laser beam. If the laser is sufficiently monochromatic, and it can be tuned over the absorption line profile of the selected atoms, information can also be obtained about the velocities of the atoms from the Doppler effect which can broaden and shift the line. In this report two topics are examined in detail. The first is the effect of high laser irradiance, which can cause 'power broadening' of the apparent absorption line profile. The second is the effect of the high magnetic field in FTU. Detailed calculations are given for LIFS of neutral iron and molybdenum atoms, including the Zeeman effect, and the implementation of LIFS for these atoms on FTU is discussed

  13. Cascade generation in Al laser induced plasma

    Science.gov (United States)

    Nagli, Lev; Gaft, Michael; Raichlin, Yosef; Gornushkin, Igor

    2018-05-01

    We found cascade IR generation in Al laser induced plasma. This generation includes doublet transitions 3s 25s 2S1/2 → 3s24p 2P1/2,3/2 → 3s24s 2S1/2; corresponding to strong lines at 2110 and 2117 nm, and much weaker lines at 1312-1315 nm. The 3s25s2S 1/2 starting IR generation level is directly pumped from the 3s23p 2P3/2 ground level. The starting level for UV generation at 396.2 nm (transitions 3s24s 2S1/2 → 4p 2P3/2) is populated due to the fast collisional processes in the plasma plume. These differences led to different time and special dependences on the lasing in the IR and UV spectral range within the aluminum laser induced plasma.

  14. Laser assisted modification and chemical metallization of electron-beam deposited ceria thin films

    International Nuclear Information System (INIS)

    Krumov, E.; Starbov, N.; Starbova, K.; Perea, A.; Solis, J.

    2009-01-01

    Excimer laser processing is applied for tailoring the surface morphology and phase composition of CeO 2 ceramic thin films. E-beam evaporation technique is used to deposit samples on stainless steel and silicate glass substrates. The films are then irradiated with ArF* excimer laser pulses under different exposure conditions. Scanning electron microscopy, optical spectrophotometry, X-ray diffractometry and EDS microanalysis are used to characterize the non-irradiated and laser-processed films. Upon UV laser exposure there is large increase of the surface roughness that is accompanied by photo-darkening and ceria reduction. It is shown that the laser induced changes in the CeO 2 films facilitate the deposition of metal nano-aggregates in a commercial copper electroless plating bath. The significance of laser modification as a novel approach for the production of CeO 2 based thin film catalysts is discussed.

  15. Laser assisted modification and chemical metallization of electron-beam deposited ceria thin films

    Energy Technology Data Exchange (ETDEWEB)

    Krumov, E., E-mail: emodk@clf.bas.bg [Central Laboratory of Photoprocesses ' Acad. Jordan Malinowski' , Bulgarian Academy of Sciences, Acad. Georgy Bonchev Str., bl. 109, 1113 Sofia (Bulgaria); Starbov, N.; Starbova, K. [Central Laboratory of Photoprocesses ' Acad. Jordan Malinowski' , Bulgarian Academy of Sciences, Acad. Georgy Bonchev Str., bl. 109, 1113 Sofia (Bulgaria); Perea, A.; Solis, J. [Instituto de Optica ' Daza de Valdes' , CSIC, 28006 Madrid (Spain)

    2009-11-15

    Excimer laser processing is applied for tailoring the surface morphology and phase composition of CeO{sub 2} ceramic thin films. E-beam evaporation technique is used to deposit samples on stainless steel and silicate glass substrates. The films are then irradiated with ArF* excimer laser pulses under different exposure conditions. Scanning electron microscopy, optical spectrophotometry, X-ray diffractometry and EDS microanalysis are used to characterize the non-irradiated and laser-processed films. Upon UV laser exposure there is large increase of the surface roughness that is accompanied by photo-darkening and ceria reduction. It is shown that the laser induced changes in the CeO{sub 2} films facilitate the deposition of metal nano-aggregates in a commercial copper electroless plating bath. The significance of laser modification as a novel approach for the production of CeO{sub 2} based thin film catalysts is discussed.

  16. Laser-induced ionization of Na vapor

    International Nuclear Information System (INIS)

    Wu, R.C.Y.; Judge, D.L.; Roussel, F.; Carre, B.; Breger, P.; Spiess, G.

    1982-01-01

    The production of Na 2 + ions by off-resonant laser excitation in the 5800-6200A region mainly results from two-photon absorption by the Na 2 molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na 2 D 1 PIμ Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na 2 + ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al we estimate that the cross section for producing Na 2 + through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na 2 molecules

  17. Shadowgraph studies of laser-assisted non-thermal structuring of thin layers on flexible substrates by shock-wave-induced delamination processes

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Pierre, E-mail: pierre.lorenz@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstraße 15, 04318 Leipzig (Germany); Smausz, Tomi [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); MTA-SZTE Research Group on Photoacoustic Spectroscopy, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Csizmadia, Tamas [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Ehrhardt, Martin; Zimmer, Klaus [Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstraße 15, 04318 Leipzig (Germany); Hopp, Bela [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary)

    2015-05-01

    Highlights: • The shock-wave-induced film delamination (SWIFD) is a laser patterning process. • The SWIFD process of CIGS solar cells was studied by shadowgraph measurements. • The study presented that SWIFD allows the structuring of CIGS solar cells. • The dynamics of the delamination process was analyzed. - Abstract: The laser-assisted microstructuring of thin films especially for electronic applications without damaging the layers or the substrates is a challenge for the laser micromachining techniques. The laser-induced thin-film patterning by ablation of the polymer substrate at the rear side that is called ‘SWIFD’ – shock-wave-induced film delamination patterning has been demonstrated. This study focuses on the temporal sequence of processes that characterize the mechanism of this SWIFD process on a copper indium gallium selenide (CIGS) solar cell stacks on polyimide. For this purpose high-speed shadowgraph experiments were performed in a pump probe experimental set-up using a KrF excimer laser for ablating the rear side of the polyimide substrate and measuring the shock wave generation at laser ablation of the polymer substrate as well as the thin-film delamination. The morphology and size of the thin-film structures were studied by scanning electron microscopy (SEM). Furthermore, the composition after the laser treatment was analyzed by energy dispersive X-ray (EDX) spectroscopy. The shadowgraph experiments allow the time-dependent identification and evaluation of the shock wave formation, substrate bending, and delamination of the thin film in dependence on the laser parameters. These results will contribute to improve the physical understanding of the laser-induced delamination effect for thin-film patterning.

  18. Laser induced fluorescence of dental caries

    Science.gov (United States)

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

    1988-01-01

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

  19. Laser-induced fluorescence imaging of bacteria

    Science.gov (United States)

    Hilton, Peter J.

    1998-12-01

    This paper outlines a method for optically detecting bacteria on various backgrounds, such as meat, by imaging their laser induced auto-fluorescence response. This method can potentially operate in real-time, which is many times faster than current bacterial detection methods, which require culturing of bacterial samples. This paper describes the imaging technique employed whereby a laser spot is scanned across an object while capturing, filtering, and digitizing the returned light. Preliminary results of the bacterial auto-fluorescence are reported and plans for future research are discussed. The results to date are encouraging with six of the eight bacterial strains investigated exhibiting auto-fluorescence when excited at 488 nm. Discrimination of these bacterial strains against red meat is shown and techniques for reducing background fluorescence discussed.

  20. Multispectral imaging system based on laser-induced fluorescence for security applications

    Science.gov (United States)

    Caneve, L.; Colao, F.; Del Franco, M.; Palucci, A.; Pistilli, M.; Spizzichino, V.

    2016-10-01

    The development of portable sensors for fast screening of crime scenes is required to reduce the number of evidences useful to be collected, optimizing time and resources. Laser based spectroscopic techniques are good candidates to this scope due to their capability to operate in field, in remote and rapid way. In this work, the prototype of a multispectral imaging LIF (Laser Induced Fluorescence) system able to detect evidence of different materials on large very crowded and confusing areas at distances up to some tens of meters will be presented. Data collected as both 2D fluorescence images and LIF spectra are suitable to the identification and the localization of the materials of interest. A reduced scan time, preserving at the same time the accuracy of the results, has been taken into account as a main requirement in the system design. An excimer laser with high energy and repetition rate coupled to a gated high sensitivity ICCD assures very good performances for this purpose. Effort has been devoted to speed up the data processing. The system has been tested in outdoor and indoor real scenarios and some results will be reported. Evidence of the plastics polypropylene (PP) and polyethilene (PE) and polyester have been identified and their localization on the examined scenes has been highlighted through the data processing. By suitable emission bands, the instrument can be used for the rapid detection of other material classes (i.e. textiles, woods, varnishes). The activities of this work have been supported by the EU-FP7 FORLAB project (Forensic Laboratory for in-situ evidence analysis in a post blast scenario).

  1. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-30

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

  2. Laser induced single spot oxidation of titanium

    International Nuclear Information System (INIS)

    Jwad, Tahseen; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-01-01

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

  3. Laser-induced-fluorescence imaging of NO in a eta-heptane- and diesel-fuel-driven diesel engine

    NARCIS (Netherlands)

    Brugman, T.M.; Klein-Douwel, R.J.H.; Huigen, G.; Walwijk, van E.; Meulen, ter J.J.

    1993-01-01

    Continuous on-line imaging by 2D-LIF techniques of in-cylinder NO distributions in a running Diesel engine is explored using an ArF-excimer laser at 193 nm operating at low power. For the first time NO excitation spectra could be measured as a result of high optical transparencies during

  4. Laser-Induced Damage with Femtosecond Pulses

    Science.gov (United States)

    Kafka, Kyle R. P.

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

  5. Effect of laser pulse energies in laser induced breakdown spectroscopy in double-pulse configuration

    International Nuclear Information System (INIS)

    Benedetti, P.A.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

    2005-01-01

    In this paper, the effect of laser pulse energy on double-pulse laser induced breakdown spectroscopy signal is studied. In particular, the energy of the first pulse has been changed, while the second pulse energy is held fixed. A systematic study of the laser induced breakdown spectroscopy signal dependence on the interpulse delay is performed, and the results are compared with the ones obtained with a single laser pulse of energy corresponding to the sum of the two pulses. At the same time, the crater formed at the target surface is studied by video-confocal microscopy, and the variation in crater dimensions is correlated to the enhancement of the laser induced breakdown spectroscopy signal. The results obtained are consistent with the interpretation of the double-pulse laser induced breakdown spectroscopy signal enhancement in terms of the changes in ambient gas pressure produced by the shock wave induced by the first laser pulse

  6. Discharge-current characteristics in UV-preionized Kr/He, F2/He gas-mixtures and KrF excimer laser gas. Shigaisen yobi denri Kr/He, F2/He kongo kitai hoden oyobi KrF laser reiki hoden no denryu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, N.; Kawakami, H.; Yukimura, K. (Doshisha University, Kyoto (Japan))

    1992-08-15

    In order to study effects of Kr and F2 on discharge characteristics of KrF excimer laser gas, gap phenomena in Kr/He and F2/He gas-mixtures were observed and discharge current (I[sub d]) was measured. In the range where Kr concentration was over 10% in Kr/He gas, in which production of filamentation as well as glow discharge started, discontinuous change in I[sub d] in the second or third half cycle was observed. According to the results of experiments and model analyses, it was considered that the discontinuity of the current showed the transition point to filamentation. When F2 concentration was in the range between 0.1 and 0.3% in F2/He mixture gas, filamentation and arc with glow were observed. Sine-waveform I[sub d] ended in the first half cycle, and began to flow again after cessation or had almost constant current due to arc and others. When F2 was over 0.4%, only are discharge was observed. It was thus found that F2 has a large effect on discharge characteristics of KrF laser gas. 18 refs., 9 figs.

  7. A general excimer signaling approach for aptamer sensors.

    Science.gov (United States)

    Wu, Cuichen; Yan, Ling; Wang, Chunming; Lin, Haoxue; Wang, Chi; Chen, Xi; Yang, Chaoyong James

    2010-06-15

    Simple, fast and direct analysis or monitoring of significant molecules in complex biological samples is important for many biological study, clinical diagnosis and forensic investigations. Herein we highlight a general method to tailor aptamer sequence into functional subunits to design target-induced light-switching excimer sensors for rapid, sensitive and selective detection of important molecules in complex biological fluids. Our approach is to split one single strand aptamer into two pieces and each terminally labeled with a pyrene molecule while maintaining their binding affinity to target molecules. In the presence of target molecules, two aptamer fragments are induced to self-assemble to form aptamer-target complex and bring two pyrene molecules into a close proximity to form an excimer, resulting in fluorescent switching from approximately 400 nm to 485 nm. With an anti-cocaine sensor, as low as 1 microM of cocaine can be detected using steady-state fluorescence assays and more importantly low picomole level of target can be directly visualized with naked eyes. Because the excimer has a long fluorescence lifetime, time-resolved measurements were used to directly detect as low as 5 microM cocaine in urine samples quantitatively without any sample pretreatment. Copyright 2010 Elsevier B.V. All rights reserved.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  9. Laser-induced incandescence applied to dusty plasmas

    NARCIS (Netherlands)

    van de Wetering, F.M.J.H.; Oosterbeek, W.; Beckers, J.; Nijdam, S.; Kovacevic, E.; Berndt, J.

    2016-01-01

    This paper reports on the laser heating of nanoparticles (diameters ≤1 μm) confined in a reactive plasma by short (150 ps) and intense (~63 mJ) UV (355 nm) laser pulses (laser-induced incandescence, LII). Important parameters such as the particle temperature and radius follow from analysis of the

  10. Excimer Laser Deposition of PLZT Thin Films

    National Research Council Canada - National Science Library

    Petersen, GAry

    1991-01-01

    .... In order to integrate these devices into optical systems, the production of high quality thin films with high transparency and perovskite crystal structure is desired. This requires development of deposition technologies to overcome the challenges of depositing and processing PLZT thin films.

  11. Excimer laser micromachining for 3D microstructure

    NARCIS (Netherlands)

    Choi, Kyung Hyun; Meijer, J.; Masuzawa, Takahisa; Kim, Dae-Hyun

    2004-01-01

    A new 3D micromachining method, called Hole Area Modulation (HAM), has been introduced to enhance the current micromachining technology. In this method, information on the machining depth is converted to the sizes of holes on the mask. The machining is carried out with a simple 2D movement of the

  12. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

    NARCIS (Netherlands)

    Habbema, L.; Verhagen, R.; Van Hal, R.; Liu, Y.; Varghese, B.

    2011-01-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create

  13. Laser-induced shockwave propagation from ablation in a cavity

    International Nuclear Information System (INIS)

    Zeng Xianzhong; Mao Xianglei; Mao, Samuel S.; Wen, S.-B.; Greif, Ralph; Russo, Richard E.

    2006-01-01

    The propagation of laser-induced shockwaves from ablation inside of cavities was determined from time-resolved shadowgraph images. The temperature and electron number density of the laser-induced plasma was determined from spectroscopic measurements. These properties were compared to those for laser ablation on the flat surface under the same energy and background gas condition. A theoretical model was proposed to determine the amount of energy and vaporized mass stored in the vapor plume based on these measurements

  14. Improved response time of laser etched polymer optical fiber Bragg grating humidity sensor

    OpenAIRE

    Zhang, Wei; Chen, Xianfeng; Liu, Chen; Lu, Yuanfu; Cardoso, Marcos; Webb, David J.

    2015-01-01

    The humidity sensor made of polymer optical fiber Bragg grating (POFBG) responds to the water content change in fiber induced by the change of environmental condition. The response time strongly depends on fiber size as the water change is a diffusion process. The ultra short laser pulses have been providing an effective micro fabrication method to achieve spatial localized modification in materials. In this work we used the excimer laser to create different microstructures (slot, D-shape) in...

  15. Excimer fluorescence of liquid crystalline systems

    Science.gov (United States)

    Sakhno, Tamara V.; Khakhel, Oleg A.; Barashkov, Nikolay N.; Korotkova, Irina V.

    1996-04-01

    The method of synchronous scanning fluorescence spectroscopy shows a presence of dimers of pyrene in a polymeric matrix. The results suggest that excimer formation takes place with dimers in liquid crystalline systems.

  16. Laser-induced fluorescence for medical diagnostics

    International Nuclear Information System (INIS)

    Andersson Engels, S.

    1989-12-01

    Laser-induced fluorescence as a tool for tissue diagnostics is discussed. Both spectrally and time-resolved fluorescence signals are studied to optimize the demarcation of diseased lesions from normal tissue. The presentation is focused on two fields of application: the identification of malignant tumours and atherosclerotic plaques. Tissue autofluorescence as well as fluorescence from administered drugs have been utilized in diseased tissue diagnosis. The fluorescence criterion for tissue diagnosis is, as far as possible, chosen to be independent of unknown fluorescence parameters, which are not correlated to the type of tissue investigated. Both a dependence on biological parameters, such as light absorption in blood, and instrumental characteristics, such as excitation pulse fluctuations and detection geometry, can be minimized. Several chemical compounds have been studied in animal experiments after intraveneous injection to verify their capacity as malignant tumour marking drugs under laser excitation and fluorescence detection. Another objective of these studies was to improve our understanding of the mechanism and chemistry behind the retention of the various drugs in tissue. The properties of a chemical which maximize its selective retention in tumours are discussed. In order to utilize this diagnostic modality, three different clinically adapted sets of instrumentation have been developed and are presented. Two of the systems are nitrogen-laser-based fluorosensors; one is a point-monitoring system with full spectral resolution and the other one is an imaging system with up to four simultaneously recorded images in different spectral bands. The third system is a low-cost point-monitoring mercury-lamp-based fluoroscence emission as well as reflection characteristics of tissue. (author)

  17. Laser-Induced Fluorescence Decay of 2-Methyl-, 2-Methoxy-, and 2-Ethylnaphthlene on α-Alumina during Temperature Programmed Desorption

    Directory of Open Access Journals (Sweden)

    Bradly B. Baer

    2013-01-01

    Full Text Available The decay of electronically excited molecular films of 2-methylnaphthalene (2-MN, 2-methoxynaphthalene (2-MeON, and 2-ethylnaphthalene (2-EN on a crystal of α-alumina was monitored as a function of temperature with temperature programmed desorption (TPD experiments. By assuming an exponential decay, the rate constants of the relaxation to the ground state were observed to have two components (±20% by laser induced fluorescence (LIF. For the 2-MeON, 2-MN, and 2-EN excimer, the longer components were 35, 25, and 23 × 106 s−1, respectively. Rate constants for the trap fluorescence for 2-MeON, 2-MN, and 2-EN were 100, 44, and 23×106 s−1, respectively. In separate experiments, the effect of a molecule that does not fluoresce and has a lower desorption temperature than the fluorophores was studied by deposition of a bilayer. 1-Chlorohexane (1-CH was chosen as the second layer to the fluorophore and the results gave clues to the complexity of the surface dynamics that occur as the surface is heated. For these bilayer systems, a second excimer formed during the TPD subsequent to the desorption of 1-CH, and their rates are given in parenthesis: for 2-MeON, 2-MN, and 2-EN, the long components were 30 (36, 25 (45, and 23 (42 × 106 s−1, respectively.

  18. Laser filament-induced aerosol formation

    Directory of Open Access Journals (Sweden)

    H. Saathoff

    2013-05-01

    Full Text Available Using the aerosol and cloud simulation chamber AIDA, we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon–oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1 for the given experimental conditions. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

  19. Volume of a laser-induced microjet

    Science.gov (United States)

    Kawamoto, Sennosuke; Hayasaka, Keisuke; Noguchi, Yuto; Tagawa, Yoshiyuki

    2015-11-01

    Needle-free injection systems are of great importance for medical treatments. In spite of their great potential, these systems are not commonly used. One of the common problems is strong pain caused by diffusion shape of the jet. To solve this problem, the usage of a high-speed highly-focused microjet as needle-free injection system is expected. It is thus crucial to control important indicators such as ejected volume of the jet for its safe application. We conduct experiments to reveal which parameter influences mostly the ejected volume. In the experiments, we use a glass tube of an inner diameter of 500 micro-meter, which is filled with the liquid. One end is connected to a syringe and the other end is opened. Radiating the pulse laser instantaneously vapors the liquid, followed by the generation of a shockwave. We find that the maximum volume of a laser-induced bubble is approximately proportional to the ejected volume. It is also found that the occurrence of cavitation does not affect the ejected volume while it changes the jet velocity.

  20. Laser induced fluorescence in atmospheric pressure discharges

    International Nuclear Information System (INIS)

    Dilecce, G; De Benedictis, S; Martini, L M; Tosi, P; Scotoni, M

    2015-01-01

    This paper offers an outline of laser induced fluorescence (LIF) diagnostics and practical recommendations for its use in atmospheric pressure discharges. LIF principles, technical requirements and rationalization of experimental outcomes by modelling are addressed. Important issues that are particularly relevant to small scale, spatially inhomogeneous discharges, like plasma-jets, are emphasized. For the first time, all collision processes and the spatial non-homogeneity of the laser beam are together accounted for in the LIF model. Saturation characteristics are discussed and used for the assessment of model parameters. A calibration procedure is discussed and implemented. Gas temperature measurements by LIF are also addressed. The whole description of the technique is given, without loss of generality, through the example of its application to the OH radical. Notes on other diatomic radicals, CH, NO and CN, are given along the paper. Some results in a RF plasma-jet are presented as an example of application in a discharge system where all the concepts developed in the paper are applied. (paper)

  1. Pressure and gap length dependence of gap breakdown voltage and discharge current of discharge-pumped KrF excimer laser. Hoden reiki KrF laser no zetsuen hakai den prime atsu to reiki denryu no atsuryoku, gap cho izon sei

    Energy Technology Data Exchange (ETDEWEB)

    Yukimura, K.; Kawakami, H. (Doshisha Univ., Tokyo (Japan)); Hitomi, K. (Kyoto Polytechnic College, Kyoto (Japan))

    1991-04-20

    On the gap destruction characteristics of UV-preionized discharge-pumped KrF excimer laser (charge transfer type) and the electric characteristics of the excited discharge, studies were made by changing the pressure (1.5-3 atm) and the discharge gap length (14-21 mm) of the discharge medium. (1) Gap breakdown voltage and the maximum current of the excited discharge give a similarity by a product of pressure and the gap length at the charge volatge. (2) Insulation breakdown of the gap occurs at the wave front of the applied voltage and the breakdown time gets delayed by the decreasing voltage applied. By setting the ionization index at constant value 20, the gap breakdown voltage is estimated at the error within 10%. (3) The relation between the maximum current, pressure and the gap length product changes the characteristics by the charge voltage of the primary condenser. With the result combined with the standardization of voltage/current of the excited discharge, the electric characteristics at the specific pressure and gap length can be readily known. 10 refs., 10 figs.

  2. The role of original surface roughness in laser-induced periodic surface structure formation process on poly-carbonate films

    International Nuclear Information System (INIS)

    Csete, M.; Hild, S.; Plettl, A.; Ziemann, P.; Bor, Zs.; Marti, O.

    2004-01-01

    Poly-carbonate films containing different types of original surface roughness were illuminated by a polarized ArF excimer laser beam having a fluence of 4 mJ/cm 2 . Atomic force microscopy was applied to study the laser-induced periodic surface structure formation process at 0 deg. , 30 deg. and 45 deg. angles of incidence. The effect of initial surface structures on the intensity distribution was investigated in cases of: (a) grains on oriented and amorphous thick films; (b) holes on thin spin-coated films; and (c) nanoparticles arranged along micrometer long sides of hexagons below the spin-coated films. The presence of the scattering objects caused symmetry breaking, if the samples were illuminated by oblique incident 's' polarized beam. The Fourier analysis of the AFM pictures has shown the competition of structures having different periods. The characteristic of the permanent surface patterns proved that the interference of the incoming beam and the beams scattered on previously existing structures is the LIPSS generating feedback process. Ring-shaped structures having 228 nm diameter were produced

  3. Experimental tests of induced spatial incoherence using short laser wavelength

    International Nuclear Information System (INIS)

    Obenschain, S.P.; Grun, J.; Herbst, M.J.

    1986-01-01

    The authors have developed a laser beam smoothing technique called induced spatial incoherence (ISI), which can produce the highly uniform focal profiles required for direct-drive laser fusion. Uniform well-controlled focal profiles are required to obtain the highly symmetric pellet implosions needed for high-energy gain. In recent experiments, the authors' tested the effects of ISI on high-power laser-target interaction. With short laser wavelength, the coupling physics dramatically improved over that obtained with an ordinary laser beam

  4. Analysis of discrete and continuous laser induced fluorescence spectra of the A 1Σsub(u)+-X 1Σsub(g)+ band system of Sr2

    International Nuclear Information System (INIS)

    Gerber, G.; Moeller, R.

    1982-01-01

    Laser induced fluorescence spectra of the gaseous Sr 2 excimer molecule have been measured. The spectra contain discrete molecular fluorescence series, regularly modulated continuous fluorescence and an unstructured continuum. Analysis of the molecular line spectra yields for the first time Dunham coefficients for the X 1 Σsub(g) + ground state and the A 1 Σsub(u) + excited state. Using the intensity distribution of the modulated continuum which is associated with bound-free transitions the repulsive potential of the ground state up to 3000 cm -1 above the dissociation limit has been determined. The unstructured continuum can be analyzed as due to two types of continuous fluorescence. The dissociation energy of Sr 2 has been determined to Dsub(e)(X) = 965 +- 45 cm -1 . (Auth.)

  5. Analysis of discrete and continuous laser induced fluorescence spectra of the A 1μ+sub(u) - X 1μ+sub(g) band system of SR2

    International Nuclear Information System (INIS)

    Gerber, G.; Moeller, R.

    1982-01-01

    Laser induced fluorescence spectra of the gaseous Sr 2 excimer molecule have been measured. The spectra contain discrete molecular fluorescence series, regularly modulated continuous fluorescence and an unstructured continuum. Analysis of the molecular line spectra yields for the first time Dunham coefficients for the X 1 μ + sub(g) ground state and the A 1 μ + sub(u) excited state. Using the intensity distribution of the modulated continuum which is associated with bound-free transitions the repulsive potential of the ground state up to 3000 cm - 1 above the dissociation limit has been determined. The unstructured continuum can be analyzed as due to two types of continuous fluorescence. The dissociation energy of Sr 2 has been determined to Dsub(e) (X) = 965 +- 45 cm - 1 . (Author)

  6. Double pulse laser ablation and plasma: Laser induced breakdown spectroscopy signal enhancement

    International Nuclear Information System (INIS)

    Babushok, V.I.; DeLucia, F.C.; Gottfried, J.L.; Munson, C.A.; Miziolek, A.W.

    2006-01-01

    A review of recent results of the studies of double laser pulse plasma and ablation for laser induced breakdown spectroscopy applications is presented. The double pulse laser induced breakdown spectroscopy configuration was suggested with the aim of overcoming the sensitivity shortcomings of the conventional single pulse laser induced breakdown spectroscopy technique. Several configurations have been suggested for the realization of the double pulse laser induced breakdown spectroscopy technique: collinear, orthogonal pre-spark, orthogonal pre-heating and dual pulse crossed beam modes. In addition, combinations of laser pulses with different wavelengths, different energies and durations were studied, thus providing flexibility in the choice of wavelength, pulse width, energy and pulse sequence. The double pulse laser induced breakdown spectroscopy approach provides a significant enhancement in the intensity of laser induced breakdown spectroscopy emission lines up to two orders of magnitude greater than a conventional single pulse laser induced breakdown spectroscopy. The double pulse technique leads to a better coupling of the laser beam with the plasma plume and target material, thus providing a more temporally effective energy delivery to the plasma and target. The experimental results demonstrate that the maximum effect is obtained at some optimum separation delay time between pulses. The optimum value of the interpulse delay depends on several factors, such as the target material, the energy level of excited states responsible for the emission, and the type of enhancement process considered. Depending on the specified parameter, the enhancement effects were observed on different time scales ranging from the picosecond time level (e.g., ion yield, ablation mass) up to the hundred microsecond level (e.g., increased emission intensity for laser induced breakdown spectroscopy of submerged metal target in water). Several suggestions have been proposed to explain

  7. Laser-induced stresses versus mechanical stress power measurements during laser ablation of solids

    International Nuclear Information System (INIS)

    Shannon, M.A.; Russo, R.E.

    1995-01-01

    Laser-induced stresses resulting from high-power laser-material interactions have been studied extensively. However, the rate of change in mechanical energy, or stress power, due to laser-induced stresses has only recently been investigated. An unanswered question for monitoring laser-material interactions in the far-field is whether stress power differs from stresses measured, particularly with respect to laser-energy coupling to a solid target. This letter shows experimental acoustic data which demonstrate that stress power measured in the far field of the target shows changes in laser-energy coupling, whereas the stresses measured do not. For the ambient medium above the target, stress power and stress together reflect changes in laser-energy coupling. copyright 1995 American Institute of Physics

  8. Laser-induced positive ion and neutral atom/molecule emissions from single-crystal CaHPO4 center dot 2H20: The role of electron-beam-induced defects

    International Nuclear Information System (INIS)

    Dawes, Mary L.; Hess, Wayne P.; Kawaguchi, Yuji; Langford, S C.; Dickinson, J. Tom

    1998-01-01

    We examine laser-induced ion and neutral emissions from single-crystal CaHPO4 center dot 2H2O (brushite), a wide-band-gap, hydrated inorganic single crystal, with 248-nm excimer laser radiation. Both laser-induced ion and neutral emissions are several orders magnitude higher following exposure to 2keV electrons at current densities of 200 uA/cm2 and doses of 1 C/cm2. In addition to intense Ca+ signals, electron-irradiated surfaces yield substantial CaO+, PO+, and P+ signals. As-grown and as-cleaved brushite show only weak neutral O2 and Ca emissions, whereas electron-irradiated surfaces yield enhanced O2, Ca, PO, PO2, and P emissions. Electron irradiation (i) significantly heats the sample, leading to thermal dehydration (CaHPO4 formation) and pyrolysis (Ca2P2O7 formation)and (ii) chemically reduces the surface via electron stimulated desorption. The thermal effects are accompanied by morphological changes, including recrystallization. Although complex, these changes lead to high defect densities, which are responsible for the dramatic enhancements in the observed laser desorption

  9. The influence of laser-particle interaction in laser induced breakdown spectroscopy and laser ablation inductively coupled plasma spectrometry

    International Nuclear Information System (INIS)

    Lindner, Helmut; Loper, Kristofer H.; Hahn, David W.; Niemax, Kay

    2011-01-01

    Particles produced by previous laser shots may have significant influence on the analytical signal in laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma (LA-ICP) spectrometry if they remain close to the position of laser sampling. The effects of these particles on the laser-induced breakdown event are demonstrated in several ways. LIBS-experiments were conducted in an ablation cell at atmospheric conditions in argon or air applying a dual-pulse arrangement with orthogonal pre-pulse, i.e., plasma breakdown in a gas generated by a focussed laser beam parallel and close to the sample surface followed by a delayed crossing laser pulse in orthogonal direction which actually ablates material from the sample and produces the LIBS plasma. The optical emission of the LIBS plasma as well as the absorption of the pre-pulse laser was measured. In the presence of particles in the focus of the pre-pulse laser, the plasma breakdown is affected and more energy of the pre-pulse laser is absorbed than without particles. As a result, the analyte line emission from the LIBS plasma of the second laser is enhanced. It is assumed that the enhancement is not only due to an increase of mass ablated by the second laser but also to better atomization and excitation conditions favored by a reduced gas density in the pre-pulse plasma. Higher laser pulse frequencies increase the probability of particle-laser interaction and, therefore, reduce the shot-to-shot line intensity variation as compared to lower particle loadings in the cell. Additional experiments using an aerosol chamber were performed to further quantify the laser absorption by the plasma in dependence on time both with and without the presence of particles. The overall implication of laser-particle interactions for LIBS and LA-ICP-MS/OES are discussed.

  10. The influence of laser-particle interaction in laser induced breakdown spectroscopy and laser ablation inductively coupled plasma spectrometry

    Science.gov (United States)

    Lindner, Helmut; Loper, Kristofer H.; Hahn, David W.; Niemax, Kay

    2011-02-01

    Particles produced by previous laser shots may have significant influence on the analytical signal in laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma (LA-ICP) spectrometry if they remain close to the position of laser sampling. The effects of these particles on the laser-induced breakdown event are demonstrated in several ways. LIBS-experiments were conducted in an ablation cell at atmospheric conditions in argon or air applying a dual-pulse arrangement with orthogonal pre-pulse, i.e., plasma breakdown in a gas generated by a focussed laser beam parallel and close to the sample surface followed by a delayed crossing laser pulse in orthogonal direction which actually ablates material from the sample and produces the LIBS plasma. The optical emission of the LIBS plasma as well as the absorption of the pre-pulse laser was measured. In the presence of particles in the focus of the pre-pulse laser, the plasma breakdown is affected and more energy of the pre-pulse laser is absorbed than without particles. As a result, the analyte line emission from the LIBS plasma of the second laser is enhanced. It is assumed that the enhancement is not only due to an increase of mass ablated by the second laser but also to better atomization and excitation conditions favored by a reduced gas density in the pre-pulse plasma. Higher laser pulse frequencies increase the probability of particle-laser interaction and, therefore, reduce the shot-to-shot line intensity variation as compared to lower particle loadings in the cell. Additional experiments using an aerosol chamber were performed to further quantify the laser absorption by the plasma in dependence on time both with and without the presence of particles. The overall implication of laser-particle interactions for LIBS and LA-ICP-MS/OES are discussed.

  11. Railgun system using a laser-induced plasma armature

    International Nuclear Information System (INIS)

    Onozuka, M.; Oda, Y.; Azuma, K.

    1996-01-01

    Development of an electromagnetic railgun system that utilizes a laser-induced plasma armature formation has been conducted to investigate the application of the railgun system for high-speed pellet injection into fusion plasmas. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. The railgun system successfully accelerated the laser-induced plasma armature by an electromagnetic force that accelerated the pellet. The highest velocity of the solid hydrogen pellets, obtained so far, was 2.6 km/sec using a 2m-long railgun. copyright 1996 American Institute of Physics

  12. Railgun system using a laser-induced plasma armature

    Science.gov (United States)

    Onozuka, Masanori; Oda, Yasushi; Azuma, Kingo

    1996-05-01

    Development of an electromagnetic railgun system that utilizes a laser-induced plasma armature formation has been conducted to investigate the application of the railgun system for high-speed pellet injection into fusion plasmas. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. The railgun system successfully accelerated the laser-induced plasma armature by an electromagnetic force that accelerated the pellet. The highest velocity of the solid hydrogen pellets, obtained so far, was 2.6 km/sec using a 2m-long railgun.

  13. Railgun system using a laser-induced plasma armature

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, M.; Oda, Y.; Azuma, K. [Mitsubishi Heavy Industries, Ltd., 3-3-1, Minatomirai, Nishi-ku, Yokohama 220-84 (Japan)

    1996-05-01

    Development of an electromagnetic railgun system that utilizes a laser-induced plasma armature formation has been conducted to investigate the application of the railgun system for high-speed pellet injection into fusion plasmas. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. The railgun system successfully accelerated the laser-induced plasma armature by an electromagnetic force that accelerated the pellet. The highest velocity of the solid hydrogen pellets, obtained so far, was 2.6 km/sec using a 2m-long railgun. {copyright} {ital 1996 American Institute of Physics.}

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

    Directory of Open Access Journals (Sweden)

    Kornilovskiy IM

    2016-04-01

    Full Text Available Igor M Kornilovskiy,1 Elmar M Kasimov,2 Ayten I Sultanova,2 Alexander A Burtsev1 1Department of Eye Diseases, Federal State Budgetary Institution “National Pirogov Medical Surgical Centre”, Ministry of Health, Moscow, Russia; 2Department of Eye Diseases, Zarifa Aliyeva National Ophthalmology Center, Ministry of Health, Baku, Azerbaijan Aim: To estimate the biomechanical effect of the laser-induced cross-linking resulting from photorefractive ablation of the cornea with riboflavin.Methods: Excimer laser ablation studies were performed ex vivo (32 eyes of 16 rabbits by phototherapeutic keratectomy (PTK and in vivo (24 eyes of 12 rabbits by transepithelial photorefractive keratectomy (TransPRK, with and without riboflavin saturation of the stroma. Then, we performed corneal optical coherence tomography on 36 eyes of 18 patients with varying degrees of myopia at different times after the TransPRK was performed with riboflavin saturation of the stroma.Results: Biomechanical testing of corneal samples saturated with riboflavin revealed cross-linking effect accompanied by the increase in tensile strength and maximum strength. PTK showed increase in tensile strength from 5.1±1.4 to 7.2±1.6 MPa (P=0.001, while TransPRK showed increase in tensile strength from 8.8±0.9 to 12.8±1.3 MPa (P=0.0004. Maximum strength increased from 8.7±2.5 to 12.0±2.8 N (P=0.005 in PTK and from 12.8±1.6 to 18.3±1.2 N (P=0.0004 in TransPRK. Clinical optical coherence tomography studies of the biomicroscopic transparent cornea at different times after TransPRK showed increased density in the surface layers of the stroma and membrane-like structure beneath the epithelium.Conclusion: Photorefractive ablation of the preliminary corneal stroma saturation with riboflavin causes the effect of laser-induced cross-linking, which is attended with an increase in corneal tensile strength, maximum strength, increased density in the surface layers of the stroma, and formation of

  15. Risks induced by laser radiation; Risques induits par le rayonnement laser

    Energy Technology Data Exchange (ETDEWEB)

    Courant, D [CEA Fontenay-aux-Roses, 92 (France). Dept. de Radiobiologie et de Radiopathologie

    2001-07-01

    The use of lasers is often dangerous because of the emitted power, the wave length, the conduction system(optical fiber, wave guide, mirrors) and the use conditions. The safety notion involves the precise knowledge of materials, the biological effects in function of laser emission parameters, the knowledge of protection standards, the observance of use rules and the personnel training. This chapter treats the risks induced by the beam. It gives the different biological effects induced by the laser beam, at the eye and skin levels that are at the origin of exposure limits and the lasers classification recommended by the protection standards. (N.C.)

  16. Faraday cup measurements of a laser-induced plasma for a laser-proton acceleration

    International Nuclear Information System (INIS)

    Park, Seong Hee; Jeong, Young Uk; Lee, Ki Tae

    2006-01-01

    Experiments for the generation of laser-induced protons were performed in collaboration with Advanced Photonics Research Institute (APRI). An intensity of 3 X 10 18 W/cm 2 was delivered to a 17-μm Al target, and the Faraday Cup signals of the charged particles generated by the laser-plasma interaction were measured. In this paper, we discuss the first experimental results of laser-induced proton generation using the APRI laser and report on the feasibility of current measurement for charged-particles when using a Faraday cup.

  17. Laser induced nuclear orientation: intersection of laser and nuclear spectroscopy

    International Nuclear Information System (INIS)

    Burns, M.; Pappas, P.; Field, M.S.

    1978-01-01

    The application of lasers to the study of hyperfine structure is reviewed with emphasis placed on the ability of the laser beam to align the nuclei in a sample. This aligning effect is especially useful if the nuclei are unstable as then the angular distribution of the subsequent nuclear radiation may be effected and information will by given about the nuclear parameters. (B.R.H.)

  18. Lasers '90: Proceedings of the 13th International Conference on Lasers and Applications, San Diego, CA, Dec. 10-14, 1990

    International Nuclear Information System (INIS)

    Harris, D.G.; Herbelin, J.

    1991-01-01

    The general topics considered are: x-ray lasers; FELs; solid state lasers; techniques and phenomena of ultrafast lasers; optical filters and free space laser communications; discharge lasers; tunable lasers; applications of lasers in medicine and surgery; lasers in materials processing; high power lasers; dynamics gratings, wave mixing, and holography; up-conversion lasers; lidar and laser radar; laser resonators; excimer lasers; laser propagation; nonlinear and quantum optics; blue-green technology; imaging; laser spectroscopy; chemical lasers; dye lasers; and lasers in chemistry

  19. Towards friction control using laser-induced periodic surface structures

    NARCIS (Netherlands)

    Eichstädt, J.; Römer, Gerardus Richardus, Bernardus, Engelina; Huis in 't Veld, Bert; Schmidt, M.; Zaeh, M.

    2011-01-01

    This paper aims at contributing to the study of laser-induced periodic surface structures (LIPSS) and the description of their tribological properties in order to facilitate the knowledge for contact mechanical applications. To obtain laser parameters for LIPSS formation, we propose to execute two

  20. Overview of applications of Laser-Induced Breakdown Spectroscopy (LIBS)

    International Nuclear Information System (INIS)

    Cremers, D.A.

    1987-01-01

    Laser-induced breakdown spectroscopy (LIBS) is a method of performing elemental analyses of solids, liquids, and gases using the microplasma produced by a focused laser pulse. Because the microplasma is formed by optical radiation, LIBS has some important advantages compared to conventional laboratory based analytical methods. Three applications are discussed which use the LIBS method. 6 refs., 8 figs., 2 tabs

  1. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    International Nuclear Information System (INIS)

    Zhang, Haisu; Tzortzakis, Stelios

    2016-01-01

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

  2. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haisu [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, Heraklion 71110 (Greece); Tzortzakis, Stelios, E-mail: stzortz@iesl.forth.gr [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, Heraklion 71110 (Greece); Materials Science and Technology Department, University of Crete, 71003 Heraklion (Greece); Science Program, Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar)

    2016-05-23

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

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

    Indian Academy of Sciences (India)

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

  4. New photoionization lasers pumped by laser-induced plasma radiation

    International Nuclear Information System (INIS)

    Hube, M.; Dieckmann, M.; Beigang, R.; Welling, H.; Wellegehausen, B.

    1988-01-01

    Innershell photoionization of atomic gases and vapors by soft x rays from a laser-produced plasma is a potential method for making lasers at short wavelengths. Normally, in such experiments only a single plasma spot or plasma line is created for the excitation. This gives high excitation rates but only a short excitation length. At high excitation rates detrimental influences, such as amplified spontaneous emission, optical saturation, or quenching processes, may decrease or even destroy a possible inversion. Therefore, it seems to be more favorable to use a number of separated plasma spots with smaller excitation rates and larger excitation lengths. As a test, a three-plasma spot device was constructed and used in the well-known Cd-photoionization laser at 442 nm. With a 600-mJ Nd:YAH laser (pulse length, 8 ns) for plasma production, output energies up to 300 μJ have been measured, which is more than a doubling of so far obtained data. On innershell excitation, levels may be populated that allow direct lasers as in the case of Cd or that are metastable and cannot be directly coupled to lower levels. In this case modifications in the excitation process are necessary. Such modifications may be an optical pump process in the atom prior to the innershell photoionization or an optical pump process (population transfer process) after the innershell ionization, leading to Raman or anti-Stokes Raman-type laser emissions. With these techniques and the developed multiplasma spot excitation device a variety of new laser emissions in K and Cs ions have been achieved which are indicated in the level schemes

  5. Robust optimization of the laser induced damage threshold of dielectric mirrors for high power lasers.

    Science.gov (United States)

    Chorel, Marine; Lanternier, Thomas; Lavastre, Éric; Bonod, Nicolas; Bousquet, Bruno; Néauport, Jérôme

    2018-04-30

    We report on a numerical optimization of the laser induced damage threshold of multi-dielectric high reflection mirrors in the sub-picosecond regime. We highlight the interplay between the electric field distribution, refractive index and intrinsic laser induced damage threshold of the materials on the overall laser induced damage threshold (LIDT) of the multilayer. We describe an optimization method of the multilayer that minimizes the field enhancement in high refractive index materials while preserving a near perfect reflectivity. This method yields a significant improvement of the damage resistance since a maximum increase of 40% can be achieved on the overall LIDT of the multilayer.

  6. Peroxy Radical Measurements via Laser Induced Fluorescence

    Science.gov (United States)

    Trawny, Katrin; Tatum Ernest, Cheryl; Novelli, Anna; Elste, Thomas; Plaß-Dülmer, Christian; Rudolf, Markus; Martinez, Monica; Harder, Hartwig; Lelieveld, Jos

    2013-04-01

    We present a newly built Laser Induced Fluorescence (LIF) system to measure the sum of all peroxy radicals (RO2) utilizing chemical conversion to OH. This instrument operates in two different modes: the ROx mode (sum of OH, HO2, and RO2) and the HOx mode (sum of OH and HO2). The HOx mode is used to derive the RO2 data from the ROx measurements. A model approach was used during instrumental development to identify the key parameters needed for the conversion process in front of the detection area and to optimize sensitivity. The instrument was then carefully characterized in various lab experiments, where it could be shown that the wall losses for HO2 are negligible and that nearly all HO2 is converted to OH in front of the detection zone. The pressure and temperature dependencies were also analyzed and assured that the instrument does not show any photolytical interference. As the instrument is calibrated with only one kind of peroxy radicals it was very important that the differences in sensitivity for different peroxy radicals are acceptable. Lab experiments as well as first results from the HOPE 2012 intensive field campaign, which took place in summer 2012 at the Global Atmosphere Watch (GAW) station of the German Weather Service, will be discussed.

  7. Medical Applications of Laser Induced Breakdown Spectroscopy

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  8. Impact of environmental contamination on laser induced damage of silica optics in Laser MegaJoule

    International Nuclear Information System (INIS)

    Bien-Aime, K.

    2009-11-01

    Laser induced damage impact of molecular contamination on fused polished silica samples in a context of high power laser fusion facility, such as Laser MegaJoule (LMJ) has been studied. One of the possible causes of laser induced degradation of optical component is the adsorption of molecular or particular contamination on optical surfaces. In the peculiar case of LMJ, laser irradiation conditions are a fluence of 10 J/cm 2 , a wavelength of 351 nm, a pulse duration of 3 ns for a single shot/days frequency. Critical compounds have been identified thanks to environmental measurements, analysis of material outgassing, and identification of surface contamination in the critical environments. Experiments of controlled contamination involving these compounds have been conducted in order to understand and model mechanisms of laser damage. Various hypotheses are proposed to explain the damage mechanism. (author)

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

    KAUST Repository

    Marengo, Marco; Marinaro, Giovanni; Kosel, Jü rgen

    2017-01-01

    Herein we present a flexible temperature sensor and a flow speed sensor based on laser-induced graphene. The main benefits arise from peculiar electrical, thermal and mechanical performances of the material thus obtained, along with a cheap

  10. Innovative applications of femtosecond laser induced self-organized nanostructure

    International Nuclear Information System (INIS)

    Shimotsuma, Yasuhiko; Miura, Kiyotaka; Sakakura, Masaaki

    2015-01-01

    The nanostructure induced by the direct-writing of femtosecond-laser pulses can open a new opportunity to develop avant-garde devices such as a 5D optical storage, polarization imaging sensor, thermoelectric conversion elements. (author)

  11. Neuroprotective Treatment of Laser-Induced Retinal Injuries

    National Research Council Canada - National Science Library

    Rosner, Mordechai

    2001-01-01

    .... It is not possible to prevent all these injuries and there is no treatment. This study was designed to evaluate the neuroprotective effect of dextromethorphan, memantine and brimonidine in our rat model of laser- induced retinal-lesions Methods...

  12. Production and Characterization of Femtosecond-Laser-Induced Air Plasma

    National Research Council Canada - National Science Library

    Armbruster, David R

    2008-01-01

    .... A beam expander was used to expand the beam to a diameter of approximately 6.5 mm, and the beam was focused through a 25 mm focal length achromatic lens to produce laser-induced plasma in ambient air...

  13. Identification of photoacoustic transients during pulsed laser ablation of the human temporal bone: an experimental model.

    Science.gov (United States)

    Wong, B J; Dickinson, M R; Berns, M W; Neev, J

    1996-12-01

    Laser ablation of hard tissues during neurotologic operations has been accomplished with continuous-wave (CW) lasers in the visible and midinfrared spectrum. The mechanism of ablation at these wavelengths is secondary to photothermal-induced tissue destruction. As a result, significant thermal damage to surrounding tissue may occur. Pulsed ultraviolet (UV) lasers have been suggested as an alternative to the argon, KTP-532, and CO2 lasers currently used in clinical practice. The pulse length of Excimer lasers are considerably shorter than the thermal diffusion time of bone tissue, and as a consequence thermal injury is minimal. This makes pulsed lasers an attractive tool for tissue ablation in the ear: in essence a "cold knife." However, the short pulse width of Excimer lasers (typically 10-150 ns) can create large thermoelastic stresses in the ablation specimen. This study identifies the presence of these photoacoustic waves during the Excimer laser treatment of the cadaveric human temporal bone. A XeCl (lambda = 308 nm, tau p = 12 ns) excimer laser was used to ablate hard tissue surrounding the oval window and facial ridge with energies of 75, 45, 25, and 12 mJ/pulse. Spot size was estimated to be 0.5 mm2. Custom high-frequency polyvinyldifluoride (PVDF) piezoelectric film transducers were fabricated and attached to the promontory, round window niche, and facial ridges. The signals were amplified using a low-noise preamplifier and recorded on a digitizing oscilloscope. Photoacoustic waves were clearly identified. Notably, large acoustic waves were measured on the promontory and on both sides of the facial ridge. The implications and clinical relevance of these findings is discussed and compared to findings obtained from a model system.

  14. Para-hydrogen raman laser and its application to laser induced chemistry

    International Nuclear Information System (INIS)

    Tashiro, Hideo

    1988-01-01

    The report outlines the mechanism of the para-hydrogen Raman laser as a infrared light source, and its application to laser induced chemistry. The Stoke's wave number after a Raman shift is equal to the difference between the wave number of the CO 2 laser used for excitation and the rotation Raman wave number of the hydrogen molecule. A Raman laser can serve as an infrared source. CO 2 laser oscillation beam in the range of 9∼11 micrometers is selected and the frequency of infrared beam is varied by changing the wave number of the CO 2 laser beam. A problem with the Raman laser is that the Raman scatterring gain is small due to a large wavelength. In developing equipment, a special mechanism is required to solve this problem. A Raman laser comprises a CO 2 laser for excitation and multi-pulse Raman cells. The combination of a TEA oscillator and amplifiers gives CO 2 pulses with a peak power of about several tens of MW. Many heavy metal compounds including fluorides, carbonyl compounds and other organic compounds, absorb light with wavelengths in the same range as those of the Raman laser. Such compounds can be dissociated directly by applying Raman laser beams. The laser will be helpful for separation of isotopes, etc. (Nogami, K.)

  15. Filament-induced remote surface ablation for long range laser-induced breakdown spectroscopy operation

    International Nuclear Information System (INIS)

    Rohwetter, Ph.; Stelmaszczyk, K.; Woeste, L.; Ackermann, R.; Mejean, G.; Salmon, E.; Kasparian, J.; Yu, J.; Wolf, J.-P.

    2005-01-01

    We demonstrate laser induced ablation and plasma line emission from a metallic target at distances up to 180 m from the laser, using filaments (self-guided propagation structures ∼ 100 μm in diameter and ∼ 5 x 10 13 W/cm 2 in intensity) appearing as femtosecond and terawatt laser pulses propagating in air. The remarkable property of filaments to propagate over a long distance independently of the diffraction limit opens the frontier to long range operation of the laser-induced breakdown spectroscopy technique. We call this special configuration of remote laser-induced breakdown spectroscopy 'remote filament-induced breakdown spectroscopy'. Our results show main features of filament-induced ablation on the surface of a metallic sample and associated plasma emission. Our experimental data allow us to estimate requirements for the detection system needed for kilometer-range remote filament-induced breakdown spectroscopy experiment

  16. Imaging femtosecond laser-induced electronic excitation in glass

    International Nuclear Information System (INIS)

    Mao Xianglei; Mao, Samuel S.; Russo, Richard E.

    2003-01-01

    While substantial progress has been achieved in understanding laser ablation on the nanosecond and picosecond time scales, it remains a considerable challenge to elucidate the underlying mechanisms during femtosecond laser material interactions. We present experimental observations of electronic excitation inside a wide band gap glass during single femtosecond laser pulse (100 fs, 800 nm) irradiation. Using a femtosecond time-resolved imaging technique, we measured the evolution of a laser-induced electronic plasma inside the glass and calculated the electron number density to be on the order of 10 19 cm -3

  17. Laser resonant ionization spectroscopy and laser-induced resonant fluorescence spectra of samarium atom

    International Nuclear Information System (INIS)

    Jin, Changtai

    1995-01-01

    We have measured new high-lying levels of Sm atom by two-colour resonant photoionisation spectroscopy; we have observed the isotope shifts of Sm atom by laser-induced resonant fluorescence spectroscopy; the lifetime of eight low-lying levels of Sm atom were measured by using pulsed laser-Boxcar technique in atomic beam.

  18. Ultrafast molecular imaging by laser-induced electron diffraction

    International Nuclear Information System (INIS)

    Peters, M.; Nguyen-Dang, T. T.; Cornaggia, C.; Saugout, S.; Charron, E.; Keller, A.; Atabek, O.

    2011-01-01

    We address the feasibility of imaging geometric and orbital structures of a polyatomic molecule on an attosecond time scale using the laser-induced electron diffraction (LIED) technique. We present numerical results for the highest molecular orbitals of the CO 2 molecule excited by a near-infrared few-cycle laser pulse. The molecular geometry (bond lengths) is determined within 3% of accuracy from a diffraction pattern which also reflects the nodal properties of the initial molecular orbital. Robustness of the structure determination is discussed with respect to vibrational and rotational motions with a complete interpretation of the laser-induced mechanisms.

  19. Visualization of cavitation bubbles induced by a laser pulse

    International Nuclear Information System (INIS)

    Testud-Giovanneschi, P.; Dufresne, D.; Inglesakis, G.

    1987-01-01

    The I.M.F.M. researchers working on Laser-Matter Interaction are studying the effects induced on matter by a pulsed radiation energy deposit. In this research, the emphasis is on the laser liquids interaction field and more particularly the cavitation induced by a laser pulse or ''optical-cavitation'' as termed by W. Lauterborn (1). For bubbles investigations, the visualizations form a basic diagnostic. This paper presents the experimental apparatus of formation of bubbles, the visualization apparatus and different typical examples of photographic recordings

  20. Excimer lamp pumped by a triggered discharge

    Energy Technology Data Exchange (ETDEWEB)

    Baldacchini, G.; Bollanti, S.; Di Lazzaro, P.; Flora, F.; Giordano, G.; Letardi, T.; Renieri, A.; Schina, G. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione; Clementi, G.; Muzzi, F.; Zheng, C.E. [EL.EN. (Electronic Engineering), Florence (Italy)

    1996-11-01

    Radiation characteristics and discharge performances of an excimer lamp are described. The discharge of the HCl/Xe gas mixture at an atmospheric pressure, occurring near the quartz tube wall, is initiated by a trigger wire. A maximum total UV energy of about 0.4 J in a (0.8-0.9) {mu}s pulse, radiated from a 10 cm discharge length, is obtained with a total discharge input energy of 8 J. Excimer lamps are the preferred choice for medical and material processing irradiations, when the monochromaticity or coherence of UV light is not required, due to their low cost, reliability and easy maintenance.

  1. Laser Induced Selective Activation For Subsequent Autocatalytic Electroless Plating

    DEFF Research Database (Denmark)

    Zhang, Yang

    . The third hypothesis is that the activation and rinsing process can be described by diffusion. This hypothesis is proved using Fick’s diffusion laws combined with the short-time-plating experiment. The influence of laser parameters on the surface structure is investigated for Nd:YAG, UV, and fiber lasers......The subject of this PhD thesis is “Laser induced selective activation for subsequent autocatalytic electroless plating.” The objective of the project is to investigate the process chains for micro structuring of polymer surfaces for selective micro metallization. Laser induced selective activation...... (LISA) is introduced and studied as a new technique for producing 3D moulded interconnect devices (3D-MIDs). This technique enables the metallization of polymer surface modified by laser and subsequently activated by a PdCl2/SnCl2 system. Various technologies exist on an industrial level...

  2. Laser-induced gas plasma machining

    Energy Technology Data Exchange (ETDEWEB)

    Elhadj, Selim; Bass, Isaac Louis; Guss, Gabriel Mark; Matthews, Manyalibo J.

    2017-10-17

    Techniques for removing material from a substrate are provided. A laser beam is focused at a distance from the surface to be treated. A gas is provided at the focus point. The gas is dissociated using the laser energy to generate gas plasma. The substrate is then brought in contact with the gas plasma to enable material removal.

  3. Laser induced breakdown spectroscopy in water | Boudjemai ...

    African Journals Online (AJOL)

    Sparks were generated in water by the focused beam of a Q-switched Nd:YAG laser Na and Cu aqueous solutions exhibited fluorescence signal on the decaying edge of plasma emission at their respective characteristic resonance lines. Potential of the laser plasma spectroscopy for in-situ pollution monitoring in natural ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-01

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

  5. Characterization of hard coatings produced by laser cladding using laser-induced breakdown spectroscopy technique

    Energy Technology Data Exchange (ETDEWEB)

    Varela, J.A.; Amado, J.M.; Tobar, M.J.; Mateo, M.P.; Yañez, A.; Nicolas, G., E-mail: gines@udc.es

    2015-05-01

    Highlights: • Chemical mapping and profiling by laser-induced breakdown spectroscopy (LIBS) of coatings produced by laser cladding. • Production of laser clads using tungsten carbide (WC) and nickel based matrix (NiCrBSi) powders. • Calibration by LIBS of hardfacing alloys with different WC concentrations. - Abstract: Protective coatings with a high abrasive wear resistance can be obtained from powders by laser cladding technique, in order to extend the service life of some industrial components. In this work, laser clad layers of self-fluxing NiCrBSi alloy powder mixed with WC powder have been produced on stainless steel substrates of austenitic type (AISI 304) in a first step and then chemically characterized by laser-induced breakdown spectroscopy (LIBS) technique. With the suitable laser processing parameters (mainly output power, beam scan speed and flow rate) and powders mixture proportions between WC ceramics and NiCrBSi alloys, dense pore free layers have been obtained on single tracks and on large areas with overlapped tracks. The results achieved by LIBS technique and applied for the first time to the analysis of laser clads provided the chemical composition of the tungsten carbides in metal alloy matrix. Different measurement modes (multiple point analyses, depth profiles and chemical maps) have been employed, demonstrating the usefulness of LIBS technique for the characterization of laser clads based on hardfacing alloys. The behavior of hardness can be explained by LIBS maps which evidenced the partial dilution of some WC spheres in the coating.

  6. Advanced excimer-based crystallization systems for production solutions

    International Nuclear Information System (INIS)

    Simon, F.; Brune, J.; Herbst, L.

    2006-01-01

    Line beam excimer laser annealing (ELA) is a well-known technique for thin Si-film crystallization and established in LTPS mass production. With introduction of sequential lateral solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS-techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM-images of process examples are shown in order to demonstrate the viability

  7. Laser induced synthesis of nanoparticles in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kazakevich, P.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38 Vavilov street, 117942 Moscow (Russian Federation); Simakin, A.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38 Vavilov street, 117942 Moscow (Russian Federation); Voronov, V.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38 Vavilov street, 117942 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38 Vavilov street, 117942 Moscow (Russian Federation)]. E-mail: shafeev@kapella.gpi.ru

    2006-04-30

    The review of results on nanoparticles formation is presented under laser ablation of Ag, Au, and Cu-containing solid targets in liquid environments (H{sub 2}O, C{sub 2}H{sub 5}OH, C{sub 2}H{sub 4}Cl{sub 2}, etc.). X-ray diffractometry (XRD), UV-vis optical transmission spectrometry, and high resolution transmission electron microscopy (HRTEM) characterize the nanoparticles. The morphology of nanoparticles is studied as the function of both laser fluence and nature of the liquid. The possibility to control the shape of nanoparticles by ablation of an Au target by an interference pattern of two laser beams is demonstrated. Formation of alloyed Au-Ag and Ag-Cu nanoparticles is reported under laser exposure of a mixture of individual nanoparticles. The effect of internal segregation of brass nanoparticles is discussed due to their small lateral dimensions. The factors are discussed that determine the distribution function of particles size under laser ablation. The influence of laser parameters as well as the nature on the liquid on the properties of nanoparticles is elucidated.

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

    Science.gov (United States)

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

    2017-12-01

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

  9. Advances in solid state laser technology for space and medical applications

    Science.gov (United States)

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

    1988-01-01

    Recent developments in laser technology and their potential for medical applications are discussed. Gas discharge lasers, dye lasers, excimer lasers, Nd:YAG lasers, HF and DF lasers, and other commonly used lasers are briefly addressed. Emerging laser technology is examined, including diode-pumped lasers and other solid state lasers.

  10. Laser-induced breakdown spectroscopy analysis of asbestos

    International Nuclear Information System (INIS)

    Caneve, L.; Colao, F.; Fabbri, F.; Fantoni, R.; Spizzichino, V.; Striber, J.

    2005-01-01

    Laser-induced breakdown spectroscopy was applied to test the possibility of detecting and identifying asbestos in different samples in view of the perspective at field operation without sample preparation which is peculiar to this technique. Several like-resin materials were first investigated by laser-induced breakdown spectroscopy, in order to find an asbestos container assuring safe laboratory operation during the material characterization aimed to identify indicators suitable for a quick identification on field. Successively, spectra of asbestos samples of both in serpentine and amphibole forms were measured and the variability in elemental composition was calculated from the emission spectra. Ratios of intensities of characteristic elements were tested as indicators for asbestos recognition. Laser-induced breakdown spectroscopy results were compared with those obtained by analyzing the same asbestos samples with a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, a good correlation was found for Mg/Si and Fe/Si, thus showing the capability of laser-induced breakdown spectroscopy as a diagnostic tool for this category of materials. In particular, it was demonstrated that the method based on two indicators derived from laser-induced breakdown spectroscopy intensity ratios allows to discriminate between asbestos and cements in single shot measurements suitable to field operation

  11. Robust nanopatterning by laser-induced dewetting of metal nanofilms

    International Nuclear Information System (INIS)

    Favazza, Christopher; Kalyanaraman, Ramki; Sureshkumar, Radhakrishna

    2006-01-01

    We have observed nanopattern formation with robust and controllable spatial ordering by laser-induced dewetting in nanoscopic metal films. Pattern evolution in Co film of thickness 1≤h≤8 nm on SiO 2 was achieved under multiple pulse irradiation using a 9 ns pulse laser. Dewetting leads to the formation of cellular patterns which evolve into polygons that eventually break up into nanoparticles with unimodal size distribution and short range ordering in nearest neighbour spacing R. Spatial ordering was attributed to a hydrodynamic thin film instability and resulted in a predictable variation of R and particle diameter D with h. The length scales R and D were found to be independent of the laser energy. These results suggest that spatially ordered metal nanoparticles can be robustly assembled by laser-induced dewetting

  12. Robust nanopatterning by laser-induced dewetting of metal nanofilms

    Energy Technology Data Exchange (ETDEWEB)

    Favazza, Christopher [Department of Physics, Washington University in St Louis, MO 63130 (United States); Kalyanaraman, Ramki [Department of Physics, Washington University in St Louis, MO 63130 (United States); Sureshkumar, Radhakrishna [Center for Materials Innovation, Washington University in St Louis, MO 63130 (United States)

    2006-08-28

    We have observed nanopattern formation with robust and controllable spatial ordering by laser-induced dewetting in nanoscopic metal films. Pattern evolution in Co film of thickness 1{<=}h{<=}8 nm on SiO{sub 2} was achieved under multiple pulse irradiation using a 9 ns pulse laser. Dewetting leads to the formation of cellular patterns which evolve into polygons that eventually break up into nanoparticles with unimodal size distribution and short range ordering in nearest neighbour spacing R. Spatial ordering was attributed to a hydrodynamic thin film instability and resulted in a predictable variation of R and particle diameter D with h. The length scales R and D were found to be independent of the laser energy. These results suggest that spatially ordered metal nanoparticles can be robustly assembled by laser-induced dewetting.

  13. Robust nanopatterning by laser-induced dewetting of metal nanofilms.

    Science.gov (United States)

    Favazza, Christopher; Kalyanaraman, Ramki; Sureshkumar, Radhakrishna

    2006-08-28

    We have observed nanopattern formation with robust and controllable spatial ordering by laser-induced dewetting in nanoscopic metal films. Pattern evolution in Co film of thickness 1≤h≤8 nm on SiO(2) was achieved under multiple pulse irradiation using a 9 ns pulse laser. Dewetting leads to the formation of cellular patterns which evolve into polygons that eventually break up into nanoparticles with unimodal size distribution and short range ordering in nearest neighbour spacing R. Spatial ordering was attributed to a hydrodynamic thin film instability and resulted in a predictable variation of R and particle diameter D with h. The length scales R and D were found to be independent of the laser energy. These results suggest that spatially ordered metal nanoparticles can be robustly assembled by laser-induced dewetting.

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

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-07-01

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

  15. Optofluidic lens actuated by laser-induced solutocapillary forces

    Science.gov (United States)

    Malyuk, A. Yu.; Ivanova, N. A.

    2017-06-01

    We demonstrate an adaptive liquid lens controlled by laser-induced solutocapillary forces. The liquid droplet serving as a lens is formed in a thin layer of binary liquid mixture by surface tension driven flows caused by the thermal action of laser irradiation. The shape of droplet, its aperture and the focal length are reversibly changed without hysteresis by varying the intensity of the laser beam. The focal length variation range of the droplet-lens lies in between infinity (a flat layer) to 15 mm (a curved interface). The droplet-lens is capable to adjust the in-plane lateral position in response to a displacement of the laser beam. The proposed laser controlled droplet-lens will enable to develop smart liquid optical devices, which can imitate the accommodation reflex and pupillary light reflex of the eye.

  16. Impurity monitoring by laser-induced fluorescence techniques

    International Nuclear Information System (INIS)

    Gelbwachs, J.A.

    1984-01-01

    Laser-induced fluorescence spectroscopy can provide a highly sensitive and selective means of detecting atomic and ionic impurities. Because the photodetector can be physically isolated from the laser-excited region, these techniques can be applied to monitoring in hostile environments. The basic concepts behind fluorescence detection are reviewed. Saturated optical excitation is shown to maximize impurity atom emission yield while mitigating effects of laser intensity fluctuations upon absolute density calibration. Monitoring in high- and low-pressure monitoring environments is compared. Methods to improve detection sensitivity by luminescence background suppression are presented

  17. Analysis of laser-induced heating in optical neuronal guidance

    DEFF Research Database (Denmark)

    Ebbesen, Christian L.; Bruus, Henrik

    2012-01-01

    Recently, it has been shown that it is possible to control the growth direction of neuronal growth cones by stimulation with weak laser light; an effect dubbed optical neuronal guidance. The effect exists for a broad range of laser wavelengths, spot sizes, spot intensities, optical intensity...... profiles and beam modulations, but it is unknown which biophysical mechanisms govern it. Based on thermodynamic modeling and simulation using published experimental parameters as input, we argue that the guidance is linked to heating. Until now, temperature effects due to laser-induced heating...

  18. Chemical consequences of laser-induced breakdown in molecular gases

    Czech Academy of Sciences Publication Activity Database

    Babánková, Dagmar; Civiš, Svatopluk; Juha, Libor

    2006-01-01

    Roč. 30, č. 2-3 (2006), s. 75-88 ISSN 0079-6727 R&D Projects: GA ČR GA203/06/1278; GA MŠk LC510; GA MŠk LC528; GA MŠk 1P04LA235 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z10100523 Keywords : laser spark * laser-induced dielectric breakdown * laser-plasma chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.500, year: 2006

  19. UV laser induced photochemistry of nitrobenzene and nitrotoluene isomers

    International Nuclear Information System (INIS)

    Kosmidis, C.; Clark, A.; Deas, R.M.; Ledingham, K.W.D.; Marshall, A.; Singhal, R.P.

    1995-01-01

    The photofragmentation of nitrobenzene and the isomers of nitrotoluene in the gas phase are studied in the wavelength region 210-270 nm using a pulsed UV laser in conjunction with a time of flight mass spectrometer. Laser induced mass spectra are analysed and compared with those produced by the electron impact (EI) technique. The generation of the observed fragment ions is explained by invoking different fragmentation pathways followed by these molecules. Observed differences in the mass spectra of the o-, m-, and p-nitrotoluene isomers are discussed as a possible way for a laser based method for their identification. (author)

  20. Instantaneous temperature field measurements using planar laser-induced fluorescence.

    Science.gov (United States)

    Seitzman, J M; Kychakoff, G; Hanson, R K

    1985-09-01

    A single-pulse, laser-induced-fluorescence diagnostic for the measurement of two-dimensional temperature fields in combustion flows is described. The method uses sheet illumination from a tunable laser to excite planar laserinduced fluorescence in a stable tracer molecule, seeded at constant mole fraction into the flow field. The temporal resolution of this technique is determined by the laser pulse length. Experimental results are presented for a rodstabilized, premixed methane-air flame, using the Q(1) (22) line of the nitric oxide A(2) Sigma(+) (v = 0) ? X(2)II((1/2))(v = 0) transition (lambda approximately 225.6 nm).

  1. Laser-induced chemical vapor deposition reactions

    International Nuclear Information System (INIS)

    Teslenko, V.V.

    1990-01-01

    The results of investigation of chemical reactions of deposition of different substances from the gas phase when using the energy of pulse quasicontinuous and continuous radiation of lasers in the wave length interval from 0.193 to 10.6 μm are generalized. Main attetion is paid to deposition of inorganic substances including nonmetals (C, Si, Ge and others), metals (Cu, Au, Zn, Cd, Al, Cr, Mo, W, Ni) and some simple compounds. Experimental data on the effect of laser radiation parameters and reagent nature (hydrides, halogenides, carbonyls, alkyl organometallic compounds and others) on the deposition rate and deposit composition are described in detail. Specific features of laser-chemical reactions of deposition and prospects of their application are considered

  2. Laser ablation of liquid surface in air induced by laser irradiation through liquid medium

    Science.gov (United States)

    Utsunomiya, Yuji; Kajiwara, Takashi; Nishiyama, Takashi; Nagayama, Kunihito; Kubota, Shiro; Nakahara, Motonao

    2010-10-01

    The pulse laser ablation of a liquid surface in air when induced by laser irradiation through a liquid medium has been experimentally investigated. A supersonic liquid jet is observed at the liquid-air interface. The liquid surface layer is driven by a plasma plume that is produced by laser ablation at the layer, resulting in a liquid jet. This phenomenon occurs only when an Nd:YAG laser pulse (wavelength: 1064 nm) is focused from the liquid onto air at a low fluence of 20 J/cm2. In this case, as Fresnel’s law shows, the incident and reflected electric fields near the liquid surface layer are superposed constructively. In contrast, when the incident laser is focused from air onto the liquid, a liquid jet is produced only at an extremely high fluence, several times larger than that in the former case. The similarities and differences in the liquid jets and atomization processes are studied for several liquid samples, including water, ethanol, and vacuum oil. The laser ablation of the liquid surface is found to depend on the incident laser energy and laser fluence. A pulse laser light source and high-resolution film are required to observe the detailed structure of a liquid jet.

  3. Molecule-binding dependent assembly of split aptamer and γ-cyclodextrin: A sensitive excimer signaling approach for aptamer biosensors

    International Nuclear Information System (INIS)

    Jin, Fen; Lian, Yan; Li, Jishan; Zheng, Jing; Hu, Yaping; Liu, Jinhua; Huang, Jin; Yang, Ronghua

    2013-01-01

    Graphical abstract: Adenosine-binding aptamer was splitted into two fragments P2 and P3 which labeled pyrene molecules, mainly produce monomer signal. γ-CD cavity brings P2 and P3 in close proximity, allowing for weak excimer emission. In the presence of target, P2 and P3 are expected to bind ATP and form an aptamer/target complex, leads to large increase of the pyrene excimer fluorescence. -- Highlights: •We assembled split aptamer and γ-cyclodextrin fluorescence biosensors for ATP detection. •The biosensor increased quantum yield and emission lifetime of the excimer. •Time-resolved fluorescence is effective for ATP assay in complicated environment. -- Abstract: A highly sensitive and selective fluorescence aptamer biosensors for the determination of adenosine triphosphate (ATP) was developed. Binding of a target with splitting aptamers labeled with pyrene molecules form stable pyrene dimer in the γ-cyclodextrin (γ-CD) cavity, yielding a strong excimer emission. We have found that inclusion of pyrene dimer in γ-cyclodextrin cavity not only exhibits additive increases in quantum yield and emission lifetime of the excimer, but also facilitates target-induced fusion of the splitting aptamers to form the aptamer/target complex. As proof-of-principle, the approach was applied to fluorescence detection of adenosine triphosphate. With an anti-ATP aptamer, the approach exhibits excimer fluorescence response toward ATP with a maximum signal-to-background ratio of 32.1 and remarkably low detection limit of 80 nM ATP in buffer solution. Moreover, due to the additive fluorescence lifetime of excimer induced by γ-cyclodextrin, time-resolved measurements could be conveniently used to detect as low as 0.5 μM ATP in blood serum quantitatively

  4. Spectroscopic analysis of femtosecond laser-induced gas breakdown

    International Nuclear Information System (INIS)

    Hermann, J.; Bruneau, S.; Sentis, M.

    2004-01-01

    The plasma generated by the interaction of a femtosecond laser pulse with gas has been analyzed using time- and space-resolved emission spectroscopy. The laser beam has been focused with a microscope objective into different gases (air, Ar, He) at pressures ranging from 10 2 to 10 5 Pa. From the analysis of spectral line emission from ions and neutral atoms, the plasma parameters and the plasma composition have been determined as a function of time and space. Furthermore, the generation of fast electrons and/or VUV radiation by the femtosecond laser interaction with the gas was brought to the fore. From the time- and space-evolution of the plasma parameters, a rough estimation of initial values of electron density and refraction index in the focal volume has been performed. These results are compared to analysis of the laser beam transmitted by the plasma. The latter show that only a small fraction of the laser energy is absorbed by the plasma while the spatial distribution of the transmitted laser beam is strongly perturbed by the plasma, which acts like a defocusing lens. However, in ambient helium, the plasma defocusing is weak due to the high ionization potential of helium. The understanding of femtosecond laser-induced gas breakdown is useful for process optimization in femtosecond laser applications like micromachining or surface microanalysis, etc

  5. Influence of laser beam profile on electromagnetically induced absorption

    International Nuclear Information System (INIS)

    Cuk, S. M.; Radonjic, M.; Krmpot, A. J.; Nikolic, S. N.; Grujic, Z. D.; Jelenkovic, B. M.

    2010-01-01

    We compared, experimentally and theoretically, Hanle electromagnetically induced absorption (EIA) obtained using Gaussian and Π-shaped laser beams 3 mm in diameter. The study was done by measuring the transmission of a laser locked to the F g =2→F e =3 transition at the D 2 line of 87 Rb in a vacuum cell. EIA linewidths obtained for the two laser profiles were significantly different in the range of laser intensities 1-4 mW/cm 2 . EIA with the Π-shaped laser beam has a broad intensity maximum and linewidths larger than those obtained with the Gaussian beam profile. We also studied Hanle EIA by measuring the transmission of selected segments of the entire laser beam by placing a small movable aperture in front of the detector. Waveforms so obtained in Hanle EIA resonances were strongly influenced both by the radial distance of the transmitted segment from the beam center and by the radial profile of the laser beam. We show that outer regions of Gaussian beam, and central regions of the Π-shaped beam generate the narrowest lines. The different behaviors of EIA owing to different beam profiles revealed by both theory and experiment indicate the importance of the radial profile of the laser beam for proper modeling of coherent effects in alkali metal vapors.

  6. Spectroscopy of beryllium-like nitrogen ions by laser-induced recombination

    International Nuclear Information System (INIS)

    Uhlenberg, G.

    1996-04-01

    The following topics were dealt with: Rydberg spectroscopy of beryllium-like nitrogen (N 3+ ) by laser-induced recombination, transition enrgies, Rydberg level shift, configuration interaction, laser intensity effect, laser band width

  7. Imaging hydrogen flames by two-photon, laser-induced fluorescence

    Science.gov (United States)

    Miles, R.; Lempert, W.; Kumar, V.; Diskin, G.

    1991-01-01

    A nonintrusive multicomponent imaging system is developed which can image hydrogen, hot oxygen, and air simultaneously. An Ar-F excimer laser is injection-locked to cover the Q1 two-photon transition in molecular hydrogen which allows the observation of both hot oxygen and cold hydrogen. Rayleigh scattering from the water molecules occurs at the same frequency as the illuminating laser allowing analysis of the air density. Images of ignited and nonignited hydrogen jets are recorded with a high-sensitivity gated video camera. The images permit the analysis of turbulent hydrogen-core jet, the combustion zone, and the surrounding air, and two-dimensional spatial correlations can be made to study the turbulent structure and couplings between different regions of the flow field. The method is of interest to the study of practical combustion systems which employ hydrogen-air diffusion flames.

  8. Laser-induced plasmas and applications

    International Nuclear Information System (INIS)

    Radziemski, L.J.

    1989-01-01

    This book discusses optical science, engineering, and technology. Topics covered include the laser and its many commercial and industrial applications, the new optical materials, gradient index optics, electro- and acousto-optics, fiber optics and communications, optical computing and pattern recognition, optical data reading, recording and storage, biomedical instrumentation, industrial robotics, integrated optics, infrared and ultraviolet systems

  9. Laser-induced cavitation based micropump

    NARCIS (Netherlands)

    Dijkink, R.J.; Ohl, C.D.

    2008-01-01

    Lab-on-a-chip devices are in strong demand as versatile and robust pumping techniques. Here, we present a cavitation based technique, which is able to pump a volume of 4000 m3 within 75 s against an estimated pressure head of 3 bar. The single cavitation event is created by focusing a laser pulse in

  10. Macroparticle acceleration by laser induced ablation pressure

    International Nuclear Information System (INIS)

    Burgess, M.D.J.; Motz, H.; Rumsby, P.T.

    1976-01-01

    In this paper it is shown that the theoretical scaling of plasma pressure is very closely obeyed using ordinary Q-switched laser pulses, resulting in velocities of over 2 x 10 4 cm s -1 . The problems associated with increasing this velocity whilst still not rupturing the pellet have also been examined and an experiment to determine the results described. (orig.) [de

  11. Ultrasound induced by CW laser cavitation bubbles

    International Nuclear Information System (INIS)

    Korneev, N; Montero, P Rodriguez; Ramos-Garcia, R; Ramirez-San-Juan, J C; Padilla-Martinez, J P

    2011-01-01

    The generation of ultrasound by a collapsing single cavitation bubble in a strongly absorbing liquid illuminated with a moderate power CW laser is described. The ultrasound shock wave is detected with hydrophone and interferometric device. To obtain a stronger pulse it is necessary to adjust a liquid absorption and a beam diameter. Their influence can be qualitatively understood with a simple model.

  12. Laser-induced grating in ZnO

    DEFF Research Database (Denmark)

    Ravn, Jesper N.

    1992-01-01

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

  13. Time-resolved study of absorbing film assisted laser induced forward transfer of Trichoderma longibrachiatum conidia

    Energy Technology Data Exchange (ETDEWEB)

    Hopp, B [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Smausz, T [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Barna, N [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Vass, Cs [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Antal, Zs [Hungarian Academy of Sciences and University of Szeged, Microbiological Research Group, PO Box 533, H-6701 Szeged (Hungary); Kredics, L [Hungarian Academy of Sciences and University of Szeged, Microbiological Research Group, PO Box 533, H-6701 Szeged (Hungary); Chrisey, D [Naval Research Laboratory, Washington, DC 20375 (United States)

    2005-03-21

    We have characterized the absorbing film assisted transfer of Trichoderma longibrachiatum conidia using a synchronized laser for illumination. The transfer laser used was a KrF excimer laser ({lambda} = 248 nm, FWHM = 30 ns) and the ejected material was illuminated parallel to the quartz plate by a nitrogen laser pumped Coumarine 153 dye laser beam ({lambda} = 453 nm, FWHM 1 ns) electronically delayed relative to the transfer UV pulse. Our time-resolved investigations determined that the ejection velocity front of the conidia plume from the donor surface during the transfer procedure was 1150 m s{sup -1} at 355 mJ cm{sup -2} applied laser fluence. On the basis of the measured data, the acceleration of the emitted conidia at the plume front was approximately 10{sup 9} x g. The conidia survived the absorbing film assisted forward transfer and associated mechanical shear without significant damages suggesting that the technique might be applicable to other more fragile types of biological objects and applications.

  14. Time-resolved study of absorbing film assisted laser induced forward transfer of Trichoderma longibrachiatum conidia

    International Nuclear Information System (INIS)

    Hopp, B; Smausz, T; Barna, N; Vass, Cs; Antal, Zs; Kredics, L; Chrisey, D

    2005-01-01

    We have characterized the absorbing film assisted transfer of Trichoderma longibrachiatum conidia using a synchronized laser for illumination. The transfer laser used was a KrF excimer laser (λ = 248 nm, FWHM = 30 ns) and the ejected material was illuminated parallel to the quartz plate by a nitrogen laser pumped Coumarine 153 dye laser beam (λ = 453 nm, FWHM 1 ns) electronically delayed relative to the transfer UV pulse. Our time-resolved investigations determined that the ejection velocity front of the conidia plume from the donor surface during the transfer procedure was 1150 m s -1 at 355 mJ cm -2 applied laser fluence. On the basis of the measured data, the acceleration of the emitted conidia at the plume front was approximately 10 9 x g. The conidia survived the absorbing film assisted forward transfer and associated mechanical shear without significant damages suggesting that the technique might be applicable to other more fragile types of biological objects and applications

  15. Laser-induced selective copper plating of polypropylene surface

    Science.gov (United States)

    Ratautas, K.; Gedvilas, M.; Stankevičiene, I.; JagminienÄ--, A.; Norkus, E.; Li Pira, N.; Sinopoli, S.; Emanuele, U.; Račiukaitis, G.

    2016-03-01

    Laser writing for selective plating of electro-conductive lines for electronics has several significant advantages, compared to conventional printed circuit board technology. Firstly, this method is faster and cheaper at the prototyping stage. Secondly, material consumption is reduced, because it works selectively. However, the biggest merit of this method is potentiality to produce moulded interconnect device, enabling to create electronics on complex 3D surfaces, thus saving space, materials and cost of production. There are two basic techniques of laser writing for selective plating on plastics: the laser-induced selective activation (LISA) and laser direct structuring (LDS). In the LISA method, pure plastics without any dopant (filler) can be used. In the LDS method, special fillers are mixed in the polymer matrix. These fillers are activated during laser writing process, and, in the next processing step, the laser modified area can be selectively plated with metals. In this work, both methods of the laser writing for the selective plating of polymers were investigated and compared. For LDS approach, new material: polypropylene with carbon-based additives was tested using picosecond and nanosecond laser pulses. Different laser processing parameters (laser pulse energy, scanning speed, the number of scans, pulse durations, wavelength and overlapping of scanned lines) were applied in order to find out the optimal regime of activation. Areal selectivity tests showed a high plating resolution. The narrowest width of a copper-plated line was less than 23 μm. Finally, our material was applied to the prototype of the electronic circuit board on a 2D surface.

  16. Laser Induced Damage in Optical Materials: 1980.

    Science.gov (United States)

    1981-10-01

    conference organization. As many of you have experienced, the printed proceedings of these Laser Damage Symposia in our personal libraries are...responsible person or agency. I look forward to our continued relationship. Finally, let me thank the organizers of this Symposium. They have done a...the professional operation of the Symposium and Ms. Susie Rivera and Ms. Sheila Aaker for their part in the preparation and publication of the

  17. Impact of mechanical stress induced in silica vacuum windows on laser-induced damage.

    Science.gov (United States)

    Gingreau, Clémence; Lanternier, Thomas; Lamaignère, Laurent; Donval, Thierry; Courchinoux, Roger; Leymarie, Christophe; Néauport, Jérôme

    2018-04-15

    At the interface between vacuum and air, optical windows must keep their optical properties, despite being subjected to mechanical stress. In this Letter, we investigate the impact of such stress on the laser-induced damage of fused silica windows at the wavelength of 351 nm in the nanosecond regime. Different stress values, from 1 to 30 MPa, both tensile and compressive, were applied. No effect of the stress on the laser-induced damage was evidenced.

  18. Femtosecond laser induced phenomena in transparent solid materials

    DEFF Research Database (Denmark)

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

    2016-01-01

    solved, especially concerning the interaction of strong, ultra-short electromagnetic pulses with matter, and also because potential advanced technologies will emerge due to the impressive capability of the intense femtosecond laser to create new material structures and hence functionalities. When......The interaction of intense femtosecond laser pulses with transparent materials is a topic that has caused great interest of scientists over the past two decades. It will continue to be a fascinating field in the coming years. This is because many challenging fundamental problems have not been......–matter interaction, and fabricate various integrated micro-devices. In recent years we have witnessed exciting development in understanding and applying femtosecond laser induced phenomena in transparent materials. The interaction of femtosecond laser pulses with transparent materials relies on non...

  19. Laser induced uranium fluorescence as an analytical method

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  1. Contributions to process monitoring by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Rusak, David Alexander

    1998-12-01

    When a pulsed laser of sufficient energy and pulse duration is brought to a focus, multi-photon ionization creates free electrons in the focal volume. These electrons are accelerated in a process known as inverse Bremsstrahlung and cause collisional ionization of species in the focal volume. More charge carriers are produced and the process continues for the duration of the laser pulse. The manifestation of this process is a visible spark or plasma which typically lasts for tens of microseconds. This laser-induced plasma can serve as a source in an atomic emission experiment. Because the composition of the plasma is determined in large part by the environment in which it forms, elements in the laser target can be determined spectroscopically. The goal of a laser-induced breakdown spectroscopy (LIBS) experiment is to establish a relationship between the concentration of an element of interest in the target and the intensity of light emitted from the laser-induced plasma at a wavelength characteristic of that element. Because LIBS requires only optical access to the sample and can perform elemental determinations in solids, liquids, or gases with little sample preparation, there is interest in using it as an on-line technique for process monitoring in a number of industrial applications. However, before the technique becomes useful in industrial applications, many issues regarding instrumentation and data analysis need to be addressed in the lab. The first two chapters of this dissertation provide, respectively, the basics of the atomic emission experiment and a background of laser-induced breakdown spectroscopy. The next two chapters examine the effect of target water content on the laser-induced plasma and the use of LIBS for analysis of aqueous samples. Chapter 5 describes construction of a fiber optic LIBS probe and its use to study temporal electron number density evolution in plasmas formed on different metals. Chapter 6 is a study of excitation, vibrational

  2. Laser-induced damage study of polymer PMMA

    International Nuclear Information System (INIS)

    Mansour, N.

    2001-01-01

    This article presents the results of bulk laser-induced damage measurements in polymer PMMA at 532 nm and 1064 nm for nanosecond laser pulses. The damage thresholds were measured for focused spot sizes ranging over two orders of magnitude. In this work, self-focusing effects were verified to be absent by measurements of breakdown thresholds using both linearly and circularly polarized light. At both 1064 nm and 532 nm, the dependence of the breakdown field, E B , on the spot size, ω, was empirically determined to be E B = C/√ω, where C depends on the wavelength. The extracted value for C(λ) at 1064 nm is larger by a factor of 5 than at 532 nm. Possible reasons for this strong dispersion and mechanism for laser-induced damage in polymer materials will be discussed

  3. Analysis of organic vapors with laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Nozari, Hadi; Tavassoli, Seyed Hassan; Rezaei, Fatemeh

    2015-01-01

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor

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

    KAUST Repository

    Marengo, Marco

    2017-12-25

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

  5. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

  6. Supersonic laser-induced jetting of aluminum micro-droplets

    International Nuclear Information System (INIS)

    Zenou, M.; Sa'ar, A.; Kotler, Z.

    2015-01-01

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets

  7. Nonequilibrium photochemical reactions induced by lasers. Technical progress report

    International Nuclear Information System (INIS)

    Steinfeld, J.I.

    1978-04-01

    Research has progressed in six principal subject areas of interest to DOE advanced (laser) isotope separation efforts. These are (1) Infrared double resonance spectroscopy of molecules excited by multiple infrared photon absorption, particularly SF 6 and vinyl chloride. (2) Infrared multiphoton excitation of metastable triplet-state molecules, e.g., biacetyl. (3) An Information Theory analysis of multiphoton excitation and collisional deactivation has been carried out. (4) The mechanism of infrared energy deposition and multiphoton-induced reactions in chlorinated ethylene derivatives; and RRKM (statistical) model accounts for all observed behavior of the system, and a deuterium-specific reaction pathway has been identified. (5) Diffusion-enhanced laser isotope separation in N 16 O/N 18 O. (6) A technical evaluation of laser-induced chemistry and isotope separation

  8. Analysis of organic vapors with laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nozari, Hadi; Tavassoli, Seyed Hassan [Laser and Plasma Research Institute, Shahid Beheshti University, G. C, 1983963113 Evin, Tehran (Iran, Islamic Republic of); Rezaei, Fatemeh, E-mail: fatemehrezaei@kntu.ac.ir [Department of Physics, K. N. Toosi University of Technology, 15875-4416 Shariati, Tehran (Iran, Islamic Republic of)

    2015-09-15

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-08-01

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

  10. Laser-induced fluorescence of oral mucosa cancer

    Science.gov (United States)

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

    2017-10-01

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

  11. Calibration-free laser-induced breakdown spectroscopy for ...

    Indian Academy of Sciences (India)

    journal of. August 2012 physics pp. 299–310. Calibration-free laser-induced ... for quantitative analysis of materials, illustrated by CF-LIBS applied to a ..... The authors are thankful to BRNS, DAE, Govt. of India for the financial support provided.

  12. Laser-induced stabilisation of the tympanic membrane

    Science.gov (United States)

    Schacht, Sophie A. L.; Stahn, Patricia; Hinsberger, Marius; Hoetzer, Benjamin; Schick, Bernhard; Wenzel, Gentiana I.

    2017-07-01

    Repeated pathologies of the tympanic membrane (TM) decrease its tension inducing conductive hearing loss and adhesive processes up to cholesteatoma. Our results regarding the development of a laser based noninvasive procedure to strengthen the structure of the TM are herein presented.

  13. Laser-induced vibrational dynamics of ozone in solid argon

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Amstrup, B.; Henriksen, Niels Engholm

    1997-01-01

    We consider the vibrational dynamics, induced by an intense infrared laser pulse, in an ozone molecule with isotopic substitution, that is, (OOO)-O-16-O-16-O-18 and compare the dynamics in the gas phase and in solid ar on. not perturbed by argon on a time-scale of a few picoseconds and selective...

  14. Impulsive Laser Induced Alignment of Molecules Dissolved in Helium Nanodroplets

    DEFF Research Database (Denmark)

    Pentlehner, Dominik; H. Nielsen, Jens; Slenczka, Alkwin

    2013-01-01

    We show that a 450 fs nonresonant, moderately intense, linearly polarized laser pulse can induce field-free molecular axis alignment of methyliodide (CH3I) molecules dissolved in a helium nanodroplet. Time-resolved measurements reveal rotational dynamics much slower than that of isolated molecules...

  15. Laser-induced onset of electrospinning

    KAUST Repository

    Sahay, R.; Teo, C. J.; Thoroddsen, Sigurdur T

    2010-01-01

    We present a method to start electrospinning from a polymeric drop. This method uses a pulsed laser which is focused inside the drop close to the liquid surface. The pulse cavitates the liquid and produces a protrusion from the tip of the drop. The protrusion narrows by drainage and vertical stretching, thus concentrating the electric field and increasing the charge density until it overcomes the surface tension and produces the electrified jet. This approach can reduce the required value of applied electric field to half of its value required to start convectional electrospinning from a stationary drop.

  16. Laser induced photonuclear and fusion-reactions

    International Nuclear Information System (INIS)

    LoDato, V.A.

    1977-01-01

    The energy release from the fusion-fission pellets is demonstrated. It is shown that the coupling of the fusion-fission process is extremely efficient provided one can obtain the proper compression heating. The pellet of an outer core of (Li6D-Li6T) with an inner core of U238 is shown to be an efficient and practical fuel and can be ignited by the present generation of lasers to produce thermonuclear burn. The demonstration of the efficiency for photonuclear and photofission pellets is shown. However no suitable gamma ray source exists at present to initiate these processes. (orig.) [de

  17. Laser-induced onset of electrospinning

    KAUST Repository

    Sahay, R.

    2010-03-09

    We present a method to start electrospinning from a polymeric drop. This method uses a pulsed laser which is focused inside the drop close to the liquid surface. The pulse cavitates the liquid and produces a protrusion from the tip of the drop. The protrusion narrows by drainage and vertical stretching, thus concentrating the electric field and increasing the charge density until it overcomes the surface tension and produces the electrified jet. This approach can reduce the required value of applied electric field to half of its value required to start convectional electrospinning from a stationary drop.

  18. Laser-induced plasmonic colours on metals

    Science.gov (United States)

    Guay, Jean-Michel; Calà Lesina, Antonino; Côté, Guillaume; Charron, Martin; Poitras, Daniel; Ramunno, Lora; Berini, Pierre; Weck, Arnaud

    2017-07-01

    Plasmonic resonances in metallic nanoparticles have been used since antiquity to colour glasses. The use of metal nanostructures for surface colourization has attracted considerable interest following recent developments in plasmonics. However, current top-down colourization methods are not ideally suited to large-scale industrial applications. Here we use a bottom-up approach where picosecond laser pulses can produce a full palette of non-iridescent colours on silver, gold, copper and aluminium. We demonstrate the process on silver coins weighing up to 5 kg and bearing large topographic variations (~1.5 cm). We find that colours are related to a single parameter, the total accumulated fluence, making the process suitable for high-throughput industrial applications. Statistical image analyses of laser-irradiated surfaces reveal various nanoparticle size distributions. Large-scale finite-difference time-domain computations based on these nanoparticle distributions reproduce trends seen in reflectance measurements, and demonstrate the key role of plasmonic resonances in colour formation.

  19. Real-time control of ultrafast laser micromachining by laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Tong Tao; Li Jinggao; Longtin, Jon P.

    2004-01-01

    Ultrafast laser micromachining provides many advantages for precision micromachining. One challenging problem, however, particularly for multilayer and heterogeneous materials, is how to prevent a given material from being ablated, as ultrafast laser micromachining is generally material insensitive. We present a real-time feedback control system for an ultrafast laser micromachining system based on laser-induced breakdown spectroscopy (LIBS). The characteristics of ultrafast LIBS are reviewed and discussed so as to demonstrate the feasibility of the technique. Comparison methods to identify the material emission patterns are developed, and several of the resulting algorithms were implemented into a real-time computer control system. LIBS-controlled micromachining is demonstrated for the fabrication of microheater structures on thermal sprayed materials. Compared with a strictly passive machining process without any such feedback control, the LIBS-based system provides several advantages including less damage to the substrate layer, reduced machining time, and more-uniform machining features

  20. Local thermodynamic equilibrium considerations in powerchip laser-induced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Merten, Jonathan A., E-mail: jmerten@astate.edu; Smith, Benjamin W., E-mail: bwsmith@chem.ufl.edu; Omenetto, Nicoló, E-mail: omenetto@chem.ufl.edu

    2013-05-01

    Time-resolved emission experiments are reported in the fast-decaying transient plasma induced by a microchip laser on an aluminum target in three different cover gases, i.e., air, argon and helium. The laser operates at 532 nm, with a repetition frequency of 1 kHz and a pulse width of less than 0.5 ns. The overall persistence of plasma emission is of the order of 100 ns. We examine the existence of local thermodynamic equilibrium (LTE) by evaluating the temporal criteria required (in addition to the McWhirter criterion), as recommended by Cristoforetti et al. (Spectrochim. Acta Part B 65, 2010, 86–95). The temporal criteria examine the evolution of temperature and electron number density and compare their rate of change to the rate at which electron collisions can thermalize the change. These considerations are used to determine time windows in which LTE may be present. Our results suggest that calibration-free LIBS measurements with these lasers may be possible for some elements at early times, especially under argon. - Highlights: ► Powerchip laser-induced plasma evolution is affected by cover gas. ► Plasma often out of LTE, despite fulfilling the McWhirter criterion ► Calibration-free LIBS may be possible with powerchip laser plasmas.