WorldWideScience

Sample records for excimer laser in-situ

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. [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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  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. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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)

  11. 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

  12. 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.

  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. 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.

  15. 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)

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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)

  1. 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)

  2. 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.

  3. 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.

  4. 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.

  5. 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)

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.)

  14. 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

  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. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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%.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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....

  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. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Comparison of retina damage thresholds simulating the femtosecond-laser in situ keratomileusis (fs-LASIK) process with two laser systems in the CW- and fs-regime

    Science.gov (United States)

    Sander, M.; Minet, O.; Zabarylo, U.; Müller, M.; Tetz, M. R.

    2012-04-01

    The femtosecond-laser in situ keratomileusis procedure affords the opportunity to correct ametropia by cutting transparent corneal tissue with ultra-short laser pulses. Thereby the tissue cut is generated by a laser-induced optical breakdown in the cornea with ultra-short laser pulses in the near-infrared range. Compared to standard procedures such as photorefractive keratectomy and laser in-situ keratomileusis with the excimer laser, where the risk potential for the eye is low due to the complete absorption of ultraviolet irradiation from corneal tissue, only a certain amount of the pulse energy is deposited in the cornea during the fs-LASIK process. The remaining energy propagates through the eye and interacts with the retina and the strong absorbing tissue layers behind. The objective of the presented study was to determine and compare the retina damage thresholds during the fs-LASIK process simulated with two various laser systems in the CW- and fs-regime.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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...

  4. 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

  5. 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.

  6. 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

  7. 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...

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. In situ reflectivity investigations of solid/liquid interface during laser backside etching

    International Nuclear Information System (INIS)

    Boehme, R.; Otto, T.; Zimmer, K.

    2006-01-01

    In situ reflectivity measurements of the solid/liquid interface with a pump-probe setup were performed during laser-induced backside wet etching (LIBWE) of fused silica with KrF excimer laser using toluene as absorbing liquid. The intensity, the temporal shape, and the duration of the reflected light measured in dependence on the laser fluence are discussed referring to the surface modification and the bubble formation. The vaporisation of the superheated liquid at the solid interface causes a considerable increase of the reflectivity and gives information about the bubble lifetime. The alterations of the reflectivity after bubbles collapse can be explained with the changed optical properties due to surface modifications of the solid surface. Comparative studies of the reflectivity at different times and the etch rate behaviour in dependence on the laser fluence show that the in situ measured surface modification begins just at the etch threshold fluence and correlates further with etch rate behaviour and the etched surface appearance. The already observed surface modification at LIBWE due to a carbon deposition and structural changes of the near surface region are approved by the changes of the interface reflectivity and emphasizes the importance of the modified surface region in the laser-induced backside wet etching process

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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...

  19. 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

  20. [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.

  1. 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)

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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...

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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)

  19. 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.

  20. 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

  1. 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

  2. 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%.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  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. 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

  15. 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 ).

  16. 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.

  17. 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

  18. 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

  19. 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}.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. Formation and control of excimer of a coumarin derivative in Langmuir–Blodgett films

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Santanu; Bhattacharjee, D.; Hussain, Syed Arshad, E-mail: sa_h153@hotmail.com

    2014-01-15

    In this communication we report the formation and control of excimer of a coumerin derivative 7-Hydroxy-N-Octadecyl Coumarin-3-Carboxamide (7HNO3C) assembled onto Langmuir–Blodgett (LB) films. Surface pressure–area per molecule isotherm revealed that 7HNO3C formed stable Langmuir monolayer at the air–water interface. Spectroscoipic characterizations confirmed the formation of excimer of 7HNO3C in the LB film prepared at 20 mN/m surface pressure. The excimer band remains present even when 7HNO3C molecules are diluted with a long chain fatty acid stearic acid in LB films. The excimer formation of 7HNO3C can be controlled by incorporating clay particle laponite in the LB film. The excimer band is totally absent in the hybrid 7HNO3C–laponite LB films. In-situ fluorescence imaging microscopy and atomic force microscopy confirmed the incorporation of clay laponite onto LB films. -- Highlights: • Formation of Langmuir monolayer and Langmuir–Blodgett (LB) film of a coumarin derivative. • Presence of excimeric species in the LB film lifted at 20 mN/m surface pressure is confirmed from the spectroscopic studies. • Control of excimer formation by incorporating clay particle laponite on to the LB film. • In-situ fluorescence imaging microscopy and atomic force microscopy confirmed the incorporation of clay laponite onto LB films.

  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. 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.

  7. 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

  8. 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.

  9. 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)

  10. 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)

  11. 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

  12. Optical properties of highly n-doped germanium obtained by in situ doping and laser annealing

    Science.gov (United States)

    Frigerio, J.; Ballabio, A.; Gallacher, K.; Giliberti, V.; Baldassarre, L.; Millar, R.; Milazzo, R.; Maiolo, L.; Minotti, A.; Bottegoni, F.; Biagioni, P.; Paul, D.; Ortolani, M.; Pecora, A.; Napolitani, E.; Isella, G.

    2017-11-01

    High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8  ×  1019 cm-3 has been achieved starting from an incorporated phosphorous concentration of 1.1  ×  1020 cm-3. Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350 nm thick layer. Photoluminescence demonstrates clear bandgap narrowing and an increased ratio of direct to indirect bandgap emission confirming the high doping densities achieved.

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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.

  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. 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.

  20. Optical properties of highly n-doped germanium obtained by in situ doping and laser annealing

    International Nuclear Information System (INIS)

    Frigerio, J; Ballabio, A; Isella, G; Gallacher, K; Millar, R; Paul, D; Gilberti, V; Baldassarre, L; Ortolani, M; Milazzo, R; Napolitani, E; Maiolo, L; Minotti, A; Pecora, A; Bottegoni, F; Biagioni, P

    2017-01-01

    High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8  ×  10 19 cm −3 has been achieved starting from an incorporated phosphorous concentration of 1.1  ×  10 20 cm −3 . Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350 nm thick layer. Photoluminescence demonstrates clear bandgap narrowing and an increased ratio of direct to indirect bandgap emission confirming the high doping densities achieved. (paper)

  1. 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)

  2. 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

  3. 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.

  4. 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.

  5. Safety, efficacy, and predictability of laser in situ keratomileusis to correct myopia or myopic astigmatism with a 750 Hz scanning-spot laser system.

    Science.gov (United States)

    Tomita, Minoru; Watabe, Miyuki; Yukawa, Satoshi; Nakamura, Nobuo; Nakamura, Tadayuki; Magnago, Thomas

    2014-02-01

    To evaluate the clinical outcomes of laser in situ keratomileusis (LASIK) to correct myopia or myopic astigmatism using the Amaris 750S 750 Hz excimer laser. Private LASIK center, Tokyo, Japan. Case series. Patients with myopia or myopic astigmatism (spherical equivalent -0.50 to -11.63 diopters [D]), a corrected distance visual acuity (CDVA) of 20/20 or better, and an estimated residual bed thickness of 300 μm or more had LASIK using the aspheric aberration-free ablation profile of the 750 Hz scanning-spot laser and the Femto LDV Crystal Line femtosecond laser for flap creation. Study parameters included uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, astigmatism, and higher-order aberrations (HOAs). The study included 1280 eyes (685 patients). At 3 months, 96.6% of eyes had a UDVA of 20/20 or better and 99.1% had 20/32 or better; 94.1% of eyes were within ± 0.50 D of the intended correction and 98.9% were within ± 1.00 D; 89.7% of eyes had no residual cylinder and 96.0% had a postoperative astigmatism of less than 0.50 D. All eyes had a postoperative CDVA of 20/20 or better. The HOAs increased postoperatively (PLaser in situ keratomileusis with the 750 Hz scanning-spot laser was safe, effective, and predictable. No specific clinical side effects that might be associated with a high repetition rate occurred. Mr. Magnago is an employee of Schwind eye-tech-solutions GmbH. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  6. Comparison of efficacy, safety, and predictability of laser in situ keratomileusis using two laser suites

    Directory of Open Access Journals (Sweden)

    Meidani A

    2016-08-01

    Full Text Available Alexandra Meidani,1–3 Chara Tzavara3 1Hypervision Laser Centre, 2Eye Day Clinic, 3Department of Hygiene, University of Athens Medical School, Centre for Health Services Research, Epidemiology and Medical Statistics, Athens, Greece Purpose: The main aim of this study was to compare the efficacy, safety, and predictability of femtosecond laser-assisted in situ keratomileusis performed by two different laser suites in the treatment of myopia for up to 6 months.Methods: In this two-site retrospective nonrandomized study, myopic eyes that underwent laser-assisted in situ keratomileusis using IntraLase FS 60 kHz formed group 1 and those using WaveLight FS200 femtosecond laser system formed group 2. Ablation was performed with Visx Star S4 IR and WaveLight EX500 Excimer lasers, respectively, in groups 1 and 2. Both groups were well matched for age, sex, and mean level of preoperative refractive spherical equivalent (MRSE. Uncorrected distance visual acuity, corrected distance visual acuity, and MRSE were evaluated preoperatively and at 1 week, 1 month, and 6 months after treatment.Results: Fifty-six eyes of 28 patients were included in the study. At 6-month follow-up postop, 78.6% of eyes in group 1 and 92.8% of eyes in group 2 achieved an uncorrected distance visual acuity of 20/20 or better (P=0.252. 35.7% and 50% in group 1 and group 2, respectively, gained one line (P=0.179. No eye lost lines of corrected distance visual acuity. Twenty-five eyes in group 1 (92.7% and 27 eyes in group 2 (96.3% had MRSE within ±0.5 D in the 6-month follow-up (P>0.999. The mean efficacy index at 6 months was similar in group 1 and group 2 (mean 1.10±0.12 [standard deviation] vs 1.10±0.1 (P=0.799. The mean safety index was similar in group 1 and group 2 (mean 1.10±0.10 [standard deviation] vs 1.10±0.09 (P=0.407.Conclusion: The outcomes were excellent between the two laser suites. There were no significant differences at 6-month follow-up postop between the two

  7. 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

  8. 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

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Ascorbic acid levels in human tears after photorefractive keratectomy, transepithelial photorefractive keratectomy, and laser in situ keratomileusis.

    Science.gov (United States)

    Bilgihan, A; Bilgihan, K; Toklu, Y; Konuk, O; Yis, O; Hasanreisoğlu, B

    2001-04-01

    To investigate the level of ascorbic acid in human tear fluid after photorefractive keratectomy (PRK), transepithelial PRK, and laser in situ keratomileusis (LASIK). Departments of Ophthalmology and Biochemistry, School of Medicine, Gazi University, Ankara, Turkey. Twenty patients (7 women and 13 men) were included in this study. Traditional PRK with epithelial scraping by a blunt spatula followed by surface ablation (7 eyes), transepithelial PRK (7 eyes), or LASIK (6 eyes) was performed. Tears were collected preoperatively and 1 and 5 days postoperatively. Ascorbic acid levels were measured using 2-4 dinitrophenylhydrazine. Ascorbic acid levels in the tear fluid were decreased significantly 1 day after PRK, transepithelial PRK, and LASIK (P <.05). On the fifth day, the ascorbic acid levels were significantly lower than preoperatively in all groups. After PRK, transepithelial PRK, and LASIK, the ascorbic acid levels of the tear fluid decreased significantly. Because ascorbic acid is the major scavenger of superoxide radicals in tears, topical ascorbic acid therapy may help eliminate the harmful effect of free radicals from excimer laser surgery.

  15. 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

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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,

  1. 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

  2. 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.

  3. 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

  4. 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...

  5. 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.

  6. 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

  7. 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

  8. Enabling laser applications in microelectronics manufacturing

    Science.gov (United States)

    Delmdahl, Ralph; Brune, Jan; Fechner, Burkhard; Senczuk, Rolf

    2016-02-01

    In this experimental study, we report on high-pulse-energy excimer laser drilling into high-performance build-up films which are pivotal in microelectronics manufacturing. Build-up materials ABF-GX13 from Ajinomoto as well as ZS-100 from Zeon Corporation are evaluated with respect to their viability for economic excimer laser-based micro-via formation. Excimer laser mask imaging projection at laser wavelengths of 193, 248 and 308 nm is employed to generate matrices of smaller micro-vias with different diameters and via pitches. High drilling quality is achievable for all excimer laser wavelengths with the fastest ablation rates measured in the case of 248 and 308 nm wavelengths. The presence of glass fillers in build-up films as in the ABF-GX13 material poses some limitations to the minimum achievable via diameter. However, surprisingly good drilling results are obtainable as long as the filler dimensions are well below the diameter of the micro-vias. Sidewall angles of vias are controllable by adjusting the laser energy density and pulse number. In this work, the structuring capabilities of excimer lasers in build-up films as to taper angle variations, attainable via diameters, edge-stop behavior and ablation rates will be elucidated.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. Effects of laser in situ keratomileusis (LASIK) on corneal biomechanical measurements with the Corvis ST tonometer.

    Science.gov (United States)

    Frings, Andreas; Linke, Stephan J; Bauer, Eva L; Druchkiv, Vasyl; Katz, Toam; Steinberg, Johannes

    2015-01-01

    This study was initiated to evaluate biomechanical changes using the Corvis ST tonometer (CST) on the cornea after laser in situ keratomileusis (LASIK). University Medical Center Hamburg-Eppendorf, Germany, and Care Vision Refractive Centers, Germany. Retrospective cohort study. This retrospective study included 37 eyes of 37 refractive patients. All CST measurements were performed 1 day before surgery and at the 1-month follow-up examination. The LASIK procedure included mechanical flap preparation using a Moria SBK microkeratome and an Allegretto excimer laser platform. Statistically significant differences were observed for mean first applanation length, mean first and second deflection lengths, mean first and second deflection amplitudes, radius of curvature, and peak distance. Significant positive correlations were found between the change (Δ) of radius of curvature and manifest refraction spherical equivalent (MRSE), ablation depth, and Δintraocular pressure as well as between AD and ΔHC-time. Each diopter of myopic correction in MRSE resulted in an increase in Δradius of curvature of 0.2 mm. Several CST parameters were statistically significantly altered by LASIK, thereby indicating that flap creation, ablation, or both, significantly change the ability of the cornea to absorb or dissipate energy.

  17. 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.

  18. 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.

  19. 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.

  20. 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)

  1. 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)

  2. [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.

  3. Laser Ablation in situ (U-Th-Sm)/He and U-Pb Double-Dating of Apatite and Zircon: Techniques and Applications

    Science.gov (United States)

    McInnes, B.; Danišík, M.; Evans, N.; McDonald, B.; Becker, T.; Vermeesch, P.

    2015-12-01

    We present a new laser-based technique for rapid, quantitative and automated in situ microanalysis of U, Th, Sm, Pb and He for applications in geochronology, thermochronometry and geochemistry (Evans et al., 2015). This novel capability permits a detailed interrogation of the time-temperature history of rocks containing apatite, zircon and other accessory phases by providing both (U-Th-Sm)/He and U-Pb ages (+trace element analysis) on single crystals. In situ laser microanalysis offers several advantages over conventional bulk crystal methods in terms of safety, cost, productivity and spatial resolution. We developed and integrated a suite of analytical instruments including a 193 nm ArF excimer laser system (RESOlution M-50A-LR), a quadrupole ICP-MS (Agilent 7700s), an Alphachron helium mass spectrometry system and swappable flow-through and ultra-high vacuum analytical chambers. The analytical protocols include the following steps: mounting/polishing in PFA Teflon using methods similar to those adopted for fission track etching; laser He extraction and analysis using a 2 s ablation at 5 Hz and 2-3 J/cm2fluence; He pit volume measurement using atomic force microscopy, and U-Th-Sm-Pb (plus optional trace element) analysis using traditional laser ablation methods. The major analytical challenges for apatite include the low U, Th and He contents relative to zircon and the elevated common Pb content. On the other hand, apatite typically has less extreme and less complex zoning of parent isotopes (primarily U and Th). A freeware application has been developed for determining (U-Th-Sm)/He ages from the raw analytical data and Iolite software was used for U-Pb age and trace element determination. In situ double-dating has successfully replicated conventional U-Pb and (U-Th)/He age variations in xenocrystic zircon from the diamondiferous Ellendale lamproite pipe, Western Australia and increased zircon analytical throughput by a factor of 50 over conventional methods

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. Laser in situ keratomileusis for residual hyperopic astigmatism after conductive keratoplasty.

    Science.gov (United States)

    Kymionis, George D; Aslanides, Ioannis M; Khoury, Aghlab N; Markomanolakis, Marinos M; Naoumidi, Tatiana; Pallikaris, loannis G

    2004-01-01

    To report a case of laser in situ keratomileusis (LASIK) in a patient with previous conductive keratoplasty. A 48-year-old man underwent conductive keratoplasty for low hyperopic astigmatism (manifest refraction OD: +2.25 -0.50 x 77 degrees; OS: +2.50 -0.50 x 105 degrees). Three months postoperatively, UCVA was 20/25 and BSCVA was 20/20 in both eyes; manifest refraction OD: -0.25 -0.75 x 110 degrees; OS: +0.75 -0.75 x 50 degrees. Sixteen months after the operation, regression of refractive outcome was (manifest) OD: +1.75 -1.25 x 90 degrees; OS: +2.50 -0.50 x 85 degrees; UCVA was 20/40 in the right eye and 20/63 in the left eye and BSCVA was 20/20 in both eyes. LASIK was performed for hyperopic regression in the left eye using an automated microkeratome (Alcon SKBM, 130-microm plate; Aesculap-Meditec MEL 70 excimer laser). LASIK was uneventful and no intraoperative or postoperative complications related to the previous conductive keratoplasty procedure or LASIK were observed. Three months after LASIK and 19 months after the initial conductive keratoplasty, the patient's left eye was emmetropic; UCVA was 20/20(-2), BSCVA was 20/20 and manifest refraction was +0.25 -0.25 x 35 degrees. There was a uniform increase in topographical steepening. Visual acuity, refraction and topographic findings remained unchanged at 6 months. Even though our experience is limited, treatment of hyperopia with LASIK in an eye with refractive regression following previous conductive keratoplasty resulted in a predicted refractive outcome, with no complications, and improvement in visual acuity at 6 months follow-up.

  11. Laser Physics and Physics with Lasers - Recent Advances

    International Nuclear Information System (INIS)

    Marowsky, G.

    2008-01-01

    This contribution reviews the development as well as recent technological advances in the field of optics with lasers and laser-related applications. Topics ranging from 'attoscience' to 'zero-modes' shall be dealt with in this presentation. Further reading in the following references is suggested: Springer Handbook of Lasers and Optics (F. Trager, ed.), 2007, ISBN-13: 978-0-387-95579-7; Chapter 11.7, Part C: Ultraviolet Lasers: Excimers, Fluorine (F2), Nitrogen (N2), pp. 764-776; Excimer Laser Technology (D. Basting, G. Marowsky, eds.) 2005, Springer, ISBN-13 978-3-540-20056-7

  12. Development in high speed and high quality laser cutting process in fiber reinforced plastics; FRP no laser ni yoru kosoku, kohinshitsu setsudan gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Ishide, T.; Shirota, H.; Matsumoto, O. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

    1996-06-01

    Trimming was performed and studied by cutting KFRP, an epoxy matrix with Kevlar fiber woven thereinto, using various laser beams. The CO2 laser is capable of high-speed cutting but the product is low in quality. The surface of a cut by the YAG laser is not high in quality even with its peak output elevated. The thermally affected area is smaller under the excimer laser but it is low in cutting speed. The ablation properties of the excimer laser were investigated and the beam was shaped into a linear beam for another experiment, but it failed to attain the target speed of cutting. Next, a combination of excimer laser and CO2 laser was used for cutting. It was so designed that the preceding CO2 laser cuts the KFRP at a high speed to leave behind a carbonized layer, which is followed by a linear beam which vaporizes the carbonized layer for removal. An optical system is adopted for reshaping the excimer oscillated beam into a tube-like beam. Optical conditions were determined for a fluence value required for the removal of the carbonized layer. When the CO2 laser was set at 160W and the excimer laser at 20W, a 1mm-thick sheet was successfully cut at a speed of 16.7mm/sec. 3 refs., 7 figs.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. Comparison of DLK incidence after laser in situ keratomileusis associated with two femtosecond lasers: Femto LDV and IntraLase FS60

    Directory of Open Access Journals (Sweden)

    Tomita M

    2013-07-01

    Full Text Available Minoru Tomita,1–3 Yuko Sotoyama,1 Satoshi Yukawa,1 Tadayuki Nakamura1 1Shinagawa LASIK Center, Chiyoda-ku, Tokyo, Japan; 2Department of Ophthalmology, Wenzhou Medical College, Wenzhou, People’s Republic of China; 3Eye Can Cataract Surgery Center, Manila, Philippines Purpose: To compare the incidence of diffuse lamellar keratitis (DLK after laser in situ keratomileusis (LASIK with flap creation using the Femto LDV and IntraLase™ FS60 femtosecond lasers. Methods: A total of 818 consecutive myopic eyes had LASIK performed using either Femto LDV or IntraLase FS60 for flap creation. The same excimer laser, the Allegretto Wave® Eye-Q Laser, was used for correcting refractive errors for all patients. In the preoperative examination, uncorrected distance visual acuity, corrected distance visual acuity, and manifest refraction spherical equivalent were measured. At the postop examination, the same examinations were performed along with a slit-lamp biomicroscopic examination, and patients with DLK were classified into stages. For the statistical analysis of the DLK occurrence rate and the visual and refractive outcomes, the Mann-Whitney’s U-test was used. Results: In the Femto LDV group with 514 eyes, 42 (8.17% had DLK. In the IntraLase FS60 group with 304 eyes, 114 (37.5% had DLK. There was a statistically significant difference in the DLK incidence rate between these groups (P < 0.0001. Both groups had excellent visual and refractive outcomes. Although low levels of DLK were observed for both groups, they did not affect visual acuity. Conclusion: While there were significantly fewer incidences of low level DLK when using Femto LDV, neither femtosecond laser induced high levels of DLK, and any postoperative DLK cleared up within 1 week. Therefore, both lasers provide excellent results, with no clinical differences, and both excel at flap creation for LASIK. Keywords: LASIK, Ziemer, Femto LDV, DLK, IntraLase FS60, femtosecond laser

  18. 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.

  19. 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

  20. Comparison of photorefractive keratectomy and laser in situ keratomileusis for myopia of -6 D or less using the Nidek EC-5000 laser.

    Science.gov (United States)

    Fernández, A P; Jaramillo, J; Jaramillo, M

    2000-01-01

    We compared the efficacy, predictability, and safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for the surgical correction of low and moderate myopia. A retrospective study was performed to evaluate uncorrected and spectacle-corrected visual acuity, and manifest refraction 1 year after PRK or LASIK. All procedures were done using an automatic microkeratome (Chiron Ophthalmic) and the Nidek EC-5000 excimer laser. PRK was performed in 75 eyes of 45 patients and LASIK in 133 eyes of 77 patients. Mean age for PRK patients was 32.8 years (range, 18 to 52 yr) and LASIK patients was 29.6 years (range, 18 to 49 yr). Mean preoperative spherical equivalent refraction for PRK patients was -3.28 D (range, -1.00 to -6.00 D) and LASIK, -3.86 D (range, -1.00 to -6.00 D). One year after surgery, mean spherical equivalent refraction for Group 1 (baseline, -1.00 to -3.00 D) PRK eyes was -0.18 +/- 0.61 D (range, -1.50 to +0.75 D) and for LASIK eyes, -0.08 +/- 0.61 D (range, -1.50 to +1.62 D), with no statistically significant difference. For Group 2 eyes (baseline, -3.25 to -6.00 D), mean spherical equivalent refraction for PRK eyes was -0.44 +/- 0.87 D (range, -2.00 to +2.12 D) and for LASIK eyes, -0.09 +/- 0.83 D (range, -1.50 to +1.75 D), with no statistically significant difference. The antilogarithm of the mean UCVA (antilogUCVA) in Group 1 for PRK was 0.79 +/- 0.21 (20/25) and for LASIK was 0.87 +/- 0.19 (20/23), with no statistically significant difference. The antilogUCVA in Group 2 for PRK eyes was 0.70 +/- 0.24 (20/28) and for LASIK eyes was 0.83 +/- 0.18 (20/24), with a statistically significant difference (0.7 vs. 0.83, P 20/40 in Group 1 for PRK was 91.5% (38 eyes) and for LASIK was 95% (50 eyes) (no statistically significant difference), and in Group 2 for PRK eyes, it was 82% (27 eyes) and 97.5% (78 eyes) for LASIK (statistically significant difference, P PRK and LASIK with the Nidek EC-5000 excimer laser are effective and safe for

  1. 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

  2. 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.

  3. 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.

  4. 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...

  5. In situ TEM Raman spectroscopy and laser-based materials modification

    Energy Technology Data Exchange (ETDEWEB)

    Allen, F.I., E-mail: fiallen@lbl.gov [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kim, E. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Andresen, N.C. [Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Grigoropoulos, C.P. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Minor, A.M., E-mail: aminor@lbl.gov [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2017-07-15

    We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS{sub 2} combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. - Highlights: • Raman spectroscopy and laser-based materials processing in a TEM are demonstrated. • A lensed Raman probe is mounted in the sample chamber for close approach. • Localized laser processing is achieved using a tapered optical fiber. • Raman spectroscopy and pulsed laser ablation of MoS{sub 2} are performed in situ.

  6. In situ TEM Raman spectroscopy and laser-based materials modification

    International Nuclear Information System (INIS)

    Allen, F.I.; Kim, E.; Andresen, N.C.; Grigoropoulos, C.P.; Minor, A.M.

    2017-01-01

    We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS_2 combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. - Highlights: • Raman spectroscopy and laser-based materials processing in a TEM are demonstrated. • A lensed Raman probe is mounted in the sample chamber for close approach. • Localized laser processing is achieved using a tapered optical fiber. • Raman spectroscopy and pulsed laser ablation of MoS_2 are performed in situ.

  7. 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.

  8. 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.

  9. 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.

  10. Straylight measurements in laser in situ keratomileusis and laser-assisted subepithelial keratectomy for myopia

    NARCIS (Netherlands)

    Lapid-Gortzak, Ruth; van der Linden, Jan Willem; van der Meulen, Ivanka; Nieuwendaal, Carla; van den Berg, Tom

    2010-01-01

    PURPOSE: To compare straylight values before and 3 months after laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) and to analyze the causes of any change. SETTING: Private refractive surgery clinic, Driebergen, The Netherlands. METHODS: Straylight was measured

  11. 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.

  12. 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

  13. 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.

  14. 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.)

  15. Acute effects of pulsed-laser irradiation on the arterial wall

    Science.gov (United States)

    Nakamura, Fumitaka; Kvasnicka, Jan; Lu, Hanjiang; Geschwind, Herbert J.; Levame, Micheline; Bousbaa, Hassan; Lange, Francoise

    1992-08-01

    Pulsed laser coronary angioplasty with an excimer or a holmium-yttrium-aluminum-garnet (Ho:YAG) laser may become an alternative treatment for patients with coronary artery disease. However, little is known about its acute consequences on the normal arterial wall. This study was designed to examine the acute histologic consequences of these two pulsed lasers on the arterial wall of normal iliac arteries in rabbits. Irradiation with each laser was performed in 15 normal iliac sites on eight male New Zealand white rabbits. The excimer laser was operated at 308 nm, 25 Hz, 50 mJ/mm2/pulse, and 135 nsec/pulse and the Ho:YAG laser was operated at 2.1 micrometers , 3/5 Hz, 400 mJ/pulse, and 250 microsecond(s) ec/pulse. The excimer and Ho:YAG laser were coupled into a multifiber wire-guided catheter of 1.4 and 1.5 mm diameter, respectively. The sites irradiated with excimer or Ho:YAG laser had the same kinds of histologic features, consisting of exfoliation of the endothelium, disorganization of internal elastic lamina, localized necrosis of vascular smooth muscle cells, and fissures in the medial layer. However, the sites irradiated with excimer laser had lower grading scores than those irradiated with Ho:YAG laser (p vascular injury.

  16. 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

  17. In-situ crack repair by laser cladding

    CSIR Research Space (South Africa)

    Van Rooyen, C

    2010-09-01

    Full Text Available Laser cladding crack repair of austenitic stainless steel vessels subjected to internal water pressure was evaluated. The purpose of this investigation was to develop process parameters for in-situ repair of through-wall cracks in components...

  18. Long-term safety and efficacy follow-up of prophylactic higher fluence collagen cross-linking in high myopic laser-assisted in situ keratomileusis

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-07-01

    Full Text Available Anastasios John KanellopoulosLaservision.gr Institute, Athens, Greece, and New York University Medical School, New York, NY, USABackground: The purpose of this study was to evaluate the safety and efficacy of ultraviolet A irradiation cross-linking on completion for cases of high myopic laser-assisted in situ keratomileusis (LASIK.Methods: Forty-three consecutive LASIK cases treated with femtosecond laser flap and the WaveLight excimer platform were evaluated perioperatively for uncorrected visual acuity, best corrected spectacle visual acuity, refraction, keratometry, topography, total and flap pachymetry, corneal optical coherence tomography, and endothelial cell count. All eyes at the completion of LASIK had cross-linking through the repositioned flap, with higher fluence (10 mW/cm2 ultraviolet light of an average 370 µm wavelength and 10 mW/cm2 fluence applied for 3 minutes following an earlier single instillation of 0.1% riboflavin within the flap interface. Mean follow-up duration was 3.5 (range 1.0–4.5 years.Results: Mean uncorrected visual acuity changed from 0.2 to 1.2, best corrected spectacle visual acuity from 1.1 to 1.2, spherical equivalent from -7.5 diopters (D to -0.2 D, keratometry from 44.5 D to 38 D, flap pachymetry from 105 µm to, total pachymetry from 525 to 405, and endothelial cell count from 2750 to 2800. None of the cases developed signs of ectasia or significant regression during follow-up.Conclusion: Prophylactic collagen cross-linking for high-risk LASIK cases appears to be a safe and effective adjunctive treatment for refractive regression and potential ectasia. This application may be viewed as prophylactic customization of the biomechanical behavior of corneal collagen.Keywords: prophylactic collagen cross-linking, laser-assisted in situ keratomileusis, high-risk, post-LASIK ectasia

  19. 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.

  20. 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

  1. Straylight before and after hyperopic laser in situ keratomileusis or laser-assisted subepithelial keratectomy

    NARCIS (Netherlands)

    Lapid-Gortzak, Ruth; van der Linden, Jan Willem; van der Meulen, Ivanka J. E.; Nieuwendaal, Carla P.; Mourits, Maarten P.; van den Berg, Thomas J. T. P.

    2010-01-01

    PURPOSE To compare straylight values before and 3 months after hyperopic laser in situ keratomileusis (LASIK) or laser-assisted subepithelial keratectomy (LASEK) and determine the cause of any change SETTING Private refractive surgery clinic, Driebergen, The Netherlands DESIGN Comparative case

  2. 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.

  3. Growth of superconducting MgB2 films by pulsed-laser deposition using a Nd-YAG laser

    International Nuclear Information System (INIS)

    Badica, P; Togano, K; Awaji, S; Watanabe, K

    2006-01-01

    Thin films of MgB 2 on r-cut Al 2 O 3 substrates have been grown by pulsed-laser deposition (PLD) using a Nd-YAG laser (fourth harmonic-266 nm) instead of the popular KrF excimer laser. The growth window to obtain superconducting films is laser energy 350-450 mJ and vacuum pressure with Ar-buffer gas of 1-8/10 Pa (initial background vacuum 0.5-1 x 10 -3 Pa). Films were deposited at room temperature and post-annealed in situ and ex situ at temperatures of 500-780 0 C and up to 1 h. Films are randomly oriented with maximum critical temperature (offset of resistive transition) of 27 K. SEM/TEM/EDS investigations show that they are mainly composed of small sphere-like particles (≤20 nm), and contain oxygen and some carbon, uniformly distributed in the flat matrix, but the amount of Mg and/or oxygen is higher in the aggregates-droplets (100-1000 nm) observed on the surface of the film's matrix. Some aspects of the processing control and dependences on film characteristics are discussed. The technique is promising for future development of coated conductors

  4. 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

  5. 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.

  6. 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

  7. Clinical outcomes of wavefront-guided laser in situ keratomileusis: 6-month follow-up.

    Science.gov (United States)

    Aizawa, Daisuke; Shimizu, Kimiya; Komatsu, Mari; Ito, Misae; Suzuki, Masanobu; Ohno, Koji; Uozato, Hiroshi

    2003-08-01

    To evaluate the clinical outcomes 6 months after wavefront-guided laser in situ keratomileusis (LASIK) for myopia in Japan. Department of Ophthalmology, Sanno Hospital, Tokyo, Japan. This prospective study comprised 22 eyes of 12 patients treated with wavefront-guided LASIK who were available for evaluation at 6 months. The mean patient age was 31.2 years +/- 8.4 (SD) (range 23 to 50 years), and the mean preoperative spherical equivalent refraction was -7.30 +/- 2.72 diopters (D) (range -2.75 to -11.88 D). In all cases, preoperative wavefront analysis was performed with a Hartmann-Shack aberrometer and the Technolas 217z flying-spot excimer laser system (Bausch & Lomb) was used with 1.0 mm and 2.0 mm spot sizes and an active eye tracker with a 120 Hz tracking rate. The clinical outcomes of wavefront-guided LASIK were evaluated in terms of safety, efficacy, predictability, stability, complications, and preoperative and postoperative aberrations. At 6 months, 10 eyes had no change in best spectacle-correct visual acuity and 10 gained 1 or more lines. The safety index was 1.11 and the efficacy index, 0.82. Slight undercorrections were observed in highly myopic eyes. In all eyes, the postoperative refraction tended slightly toward myopia for 3 months and stabilized after that. No complication such as epithelial ingrowth, diffuse lamellar keratitis, or infection was observed. Comparison of the preoperative and postoperative aberrations showed that 2nd-order aberrations decreased and higher-order aberrations increased. In the 3rd order, aberrations increased in the high-myopia group (-6.0 D or worse) and decreased in the low to moderate-myopia group (better than -6.0 D). Wavefront-guided LASIK was a good option for refractive surgery, although a longer follow-up in a larger study is required.

  8. 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

  9. 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)

  10. Excimer-mediated photoionization of covalently-linked diaryl compounds: Energy thresholds for excimer formation and excimer-assisted photoionization of jet-cooled bis (9-Fluorenyl) methane

    International Nuclear Information System (INIS)

    Lee, Jae Kwang; Kang, Heun Kag; Cho, Han Joung; Boo, Bong Hyun; Lim, Edward C.

    2001-01-01

    Diarylakanes capable of adopting a face-to face arrangement of the two aromatic rings are ideal systems in which to probe the excited-state dynamics leading to excimer formation and the role of the singlet excimer in the photoionization of covalently linked bichromophoric molecules. Bis (9-eluorenyl) methane, BFM, is a good example of such diaryl compounds. Boo and co-workers have shown that BFM exhibits excrimer fluorescence in solution at ambient temperatures. An Arrhenius plot of the temperature-dependent excimer formation rate yielded activation energy of about 15 kJ·mol -1 . It has been proposed that the activation energy is related to the barrier for transforming the initial S 1 geometry to the face-to face (sandwich-pair) geometry of the intramolecular singlet excimer. This is accord with the study of an intramolecular excimer formation in jet-cooled 1, 3-diphenylpropane (DPP), and that of an intramolecular exciplex formation in 1-(9-anthryl)-3-(4-N, N-dimethylaniline) propane, which indicate that the energy threshold for such conformational changes is about 11 kJ·mol -1 .

  11. Patient-reported outcomes 5 years after laser in situ keratomileusis.

    Science.gov (United States)

    Schallhorn, Steven C; Venter, Jan A; Teenan, David; Hannan, Stephen J; Hettinger, Keith A; Pelouskova, Martina; Schallhorn, Julie M

    2016-06-01

    To assess vision-related, quality-of-life outcomes 5 years after laser in situ keratomileusis (LASIK) and determine factors predictive of patient satisfaction. Optical Express, Glasgow, Scotland. Retrospective case series. Data from patients who had attended a clinical examination 5 years after LASIK were analyzed. All treatments were performed using the Visx Star S4 IR excimer laser. Patient-reported satisfaction, the effect of eyesight on various activities, visual phenomena, and ocular discomfort were evaluated 5 years postoperatively. Multivariate regression analysis was performed to determine factors affecting patient satisfaction. The study comprised 2530 patients (4937 eyes) who had LASIK. The mean age at the time of surgery was 42.4 years ± 12.5 (SD), and the preoperative manifest spherical equivalent ranged from -11.0 diopters (D) to +4.88 D. Five years postoperatively, 79.3% of eyes were within ±0.50 D of emmetropia and 77.7% of eyes achieved monocular uncorrected distance visual acuity (UDVA) and 90.6% of eyes achieved binocular UDVA of 20/20 or better. Of the patients, 91.0% said they were satisfied with their vision and 94.9% did not wear distance correction. Less than 2.0% of patients noticed visual phenomena, even with spectacle correction. Major predictors of patient satisfaction 5 years postoperatively were postoperative binocular UDVA (37.6% variance explained by regression model), visual phenomena (relative contribution of 15.0%), preoperative and postoperative sphere and their interactions (11.6%), and eyesight-related difficulties with various activities such as night driving, outdoor activities, and reading (10.2%). Patient-reported quality-of-life and satisfaction rates remained high 5 years after LASIK. Uncorrected vision was the strongest predictor of satisfaction. Dr. S.C. Schallhorn is a consultant to Abbott Medical Optics, Inc., Zeiss Meditec AG, and Autofocus Inc. and a global medical director for Optical Express. No other

  12. 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.

  13. A comparative study of size distribution of nanoparticles generated by laser ablation of graphite and tungsten

    International Nuclear Information System (INIS)

    Marton, Zs.; Landstroem, L.; Boman, M.; Heszler, P.

    2003-01-01

    Nanoparticles (NPs) were generated by ArF excimer laser ablation of graphite and tungsten targets in N 2 ambient at atmospheric pressure. The size distribution of the particles was monitored in situ by a scanning mobility particle sizer (SMPS) system, based on differential mobility analyser. The experimental conditions made possible to record the size distributions in the 7-133-nm diameter range and results are presented for different laser fluences, repetition rates and ablated areas, respectively. Material analysis was performed by photoelectron spectroscopy (XPS), Raman spectroscopy, X ray diffraction and SEM

  14. 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.

  15. Evaluation of iris recognition system for wavefront-guided laser in situ keratomileusis for myopic astigmatism.

    Science.gov (United States)

    Ghosh, Sudipta; Couper, Terry A; Lamoureux, Ecosse; Jhanji, Vishal; Taylor, Hugh R; Vajpayee, Rasik B

    2008-02-01

    To evaluate the visual and refractive outcomes of wavefront-guided laser in situ keratomileusis (LASIK) using an iris recognition system for the correction of myopic astigmatism. Centre for Eye Research Australia, Melbourne Excimer Laser Research Group, and Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia. A comparative analysis of wavefront-guided LASIK was performed with an iris recognition system (iris recognition group) and without iris recognition (control group). The main parameters were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity, amount of residual cylinder, manifest spherical equivalent (SE), and the index of success using the Alpins method of astigmatism analysis 1 and 3 months postoperatively. A P value less than 0.05 was considered statistically significant. Preoperatively, the mean SE was -4.32 diopters (D) +/- 1.59 (SD) in the iris recognition group (100 eyes) and -4.55 +/- 1.87 D in the control group (98 eyes) (P = .84). At 3 months, the mean SE was -0.05 +/- 0.21 D and -0.20 +/- 0.40 D, respectively (P = .001), and an SE within +/-0.50 D of emmetropia was achieved in 92.0% and 85.7% of eyes, respectively (P = .07). At 3 months, the UCVA was 20/20 or better in 90.0% and 76.5% of eyes, respectively. A statistically significant difference in the amount of astigmatic correction was seen between the 2 groups (P = .00 and P = .01 at 1 and 3 months, respectively). The index of success was 98.0% in the iris recognition group and 81.6% in the control group (P = .03). Iris recognition software may achieve better visual and refractive outcomes in wavefront-guided LASIK for myopic astigmatism.

  16. In situ laser processing in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-15

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

  17. [Advantages and disadvantages of femtosecond laser assisted LASIK and SMILE].

    Science.gov (United States)

    Zhang, F J; Sun, M S

    2018-01-11

    With the development of excimer laser and femtosecond laser equipment, application of diversified and customized surgical decision in modern corneal refractive surgery has been an inevitable trend. However, how to make a personalized decision with an accurate surgical design to achieve better visual quality becomes the main focus in clinical applications. Small-incision lenticule extraction (SMILE) and femtosecond assisted laser in situ keratomileusis (FS-LASIK) have been commonly acknowledged as the mainstream of corneal refractive surgery for ametropia correction nowadays. Both methods have been verified by clinical practice for many years. This article compares and elaborates the different characteristics with advantages and disadvantages of the two methods so as to provide some reasonable treatment options for refractive surgery. (Chin J Ophthalmol, 2018, 54: 7-10) .

  18. LASIK eye surgery

    Science.gov (United States)

    ... Assisted In Situ Keratomileusis; Laser vision correction; Nearsightedness - Lasik; Myopia - Lasik ... cornea (curvature) and the length of the eye. LASIK uses an excimer laser (an ultraviolet laser) to ...

  19. Photorefractive keratectomy versus laser in situ keratomileusis for moderate to high myopia. A randomized prospective study.

    Science.gov (United States)

    Hersh, P S; Brint, S F; Maloney, R K; Durrie, D S; Gordon, M; Michelson, M A; Thompson, V M; Berkeley, R B; Schein, O D; Steinert, R F

    1998-08-01

    This report presents the results of a randomized clinical trial of photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK). A randomized, prospective multicenter clinical trial. A total of 220 eyes of 220 patients entered the study cohort: 105 randomized to PRK and 115 to LASIK. The mean preoperative manifest refraction spherical equivalent was -9.23 diopters (D) in the PRK group and -9.30 D in the LASIK group. All patients received a one-pass, multizone excimer laser ablation as part of either a PRK or LASIK procedure using the Summit Apex excimer laser. Attempted corrections ranged from 6.00 to 15.00 D. Data on uncorrected and spectacle-corrected visual acuity, predictability,and stability of refraction, corneal haze, and flap complications were analyzed. Patients were observed for up to 6 months. One day after surgery, 0 (0.0%) and 3 (4.5%) eyes in the PRK group saw 20/20 and 20/40 or better uncorrected, respectively, while 7 (10%) and 48 (68.6%) eyes in the LASIK group saw 20/20 and 20/40 or better, respectively. At 6 months after PRK, 13 (19.1%) and 45 (66.2%) eyes saw 20/20 and 20/40 or better, respectively, while after LASIK, 16 (26.2%) and 34 (55.7%) eyes saw 20/20 and 20/40 or better, respectively (odds ratio = 0.56 for likelihood of uncorrected visual acuity PRK vs. LASIK, 95% confidence interval [CI] = 0.31-1.19). After PRK, 39 eyes (57.4%) were within 1.0 D of attempted correction compared with 24 eyes (40.7%) in the LASIK group (odds ratio = 0.50 for likelihood fo undercorrection 1.0 D for PRK vs. LASIK, 95% CI = 0.24-1.04); however, the standard deviation of the predictability was similar between groups: 1.01 D for PRK and 1.22 D for LASIK. From months 1 to 6, there was an average regression of 0.89 D in the PRK group and 0.55 D in the LASIK group. After PRK, eight eyes (11.8%) had a decrease in spectacle-corrected visual acuity of two Snellen lines or more; after LASIK, two eyes (3.2%) had a decrease of two lines or more

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-02-25

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

  1. Ten years after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for moderate to high myopia (control-matched study).

    Science.gov (United States)

    Alió, J L; Ortiz, D; Muftuoglu, O; Garcia, M J

    2009-10-01

    To compare the long-term outcomes of photorefractive keratectomy (PRK) and laser in situ keratomilesis (LASIK) for myopia between -6 and -10 D. A retrospective, control-matched study including 68 eyes, 34 which underwent PRK and 34 LASIK, with myopia between -6 and -10 D, operated using the VISX 20/20 excimer laser, was performed. Optical zones of 5.5 to 6 mm were used. All PRK-treated eyes were matched with LASIK-treated eyes of the same age, spherical equivalent within +/-1.25 D, sphere within +/-1.5 D and cylinder within +/-2.5 D. All patients were evaluated 3 months, 1 year, 2 years, 5 years and 10 years after surgery. The main outcomes measures were refractive predictability and stability, safety, efficacy and re-treatment rate. At 10 years, 20 (71%) and 23 (88%) were within +/-1.00 D after PRK and LASIK respectively. The re-treatment rate was 35% and 18% respectively. No eye lost more than two lines of BSCVA in both groups. The efficacy was 0.90 for PRK and 0.95 for LASIK. Both PRK and LASIK were safe for moderate myopia. LASIK demonstrated slightly better efficacy, predictability, and less rate of re-treatment after 10 years. The technical improvements should be taken into account when comparing these results with those obtained more recently.

  2. 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.

  3. Fiscal 2000 survey report. Research on laser-aided photolysis of environmental pollutant in liquid phase system; 2000 nendo ekisokei ni okeru kankyo osen busshitsu no laser hikari bunkai gijutsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    Experiments were conducted on laser-aided decomposition and removal of chemical substances in liquid phase systems on the assumption that there existed chemical pollutants in wastewater or water after washing burned ash. The aim of the research was to split carbon-chlorine bonds and break benzene rings, the two being the cause of harmfulness, and experiments were conducted using chlorophenol. The photolytic lasers were ArF excimer laser and KrF excimer laser. It was found that the reduction rate of chlorophenol in a water solution under excimer laser irradiation was 1.7 times higher under KrF laser than under ArF laser. For mediums other than water, isopropanol was used, more convenient than chlorophenol in separating organic pollutants from burned ash and the like. In this case, organochlorine compounds were generated at the beginning, but they disappeared when irradiation was prolonged. It was demonstrated that the laser-aided environmental cleaning technology would find a very wide scope of application as an effective photolytic means. (NEDO)

  4. 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

  5. Contrasting the beam interaction characteristics of selected lasers with a partially stabilized zirconia bio-ceramic

    International Nuclear Information System (INIS)

    Lawrence, J.

    2002-01-01

    Differences in the beam interaction characteristics of a CO 2 laser, a Nd:YAG laser, a high power diode laser (HPDL) and an excimer laser with a partially stabilized zirconia bio-ceramic have been studied. A derivative of Beer-Lambert's law was applied and the laser beam absorption lengths of the four lasers were calculated as 33.55x10 -3 cm for the CO 2 laser, 18.22x10 -3 cm for the Nd : YAG laser, 17.17x10 -3 cm for the HPDL and 8.41x10 -6 cm for the excimer laser. It was determined graphically that the fluence threshold values at which significant material removal was effected by the CO 2 laser, the Nd:YAG laser, the HPDL and the excimer laser were 52 J cm -2 , 97 J cm -2 , 115 J cm -2 and 0.48 J cm -2 , respectively. The thermal loading value for the CO 2 laser, the Nd : YAG laser, the HPDL and the excimer laser were calculated as being 1.55 kJ cm -3 , 5.32 kJ cm 3 , 6.69 kJ cm -3 and 57.04 kJ cm -3 , respectively. (author)

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Laser in situ keratomileusis enhancements with the Ziemer FEMTO LDV femtosecond laser following previous LASIK treatments.

    Science.gov (United States)

    Pietilä, Juhani; Huhtala, Anne; Mäkinen, Petri; Uusitalo, Hannu

    2013-02-01

    The aim of this paper is to present the accuracy, predictability, and safety outcomes of LASIK enhancements performed with the FEMTO LDV femtosecond laser (Ziemer Ophthalmic Systems, Port, Switzerland) and the Allegretto Wave Concerto 500 Hz excimer laser (Wavelight AG, Erlangen, Germany), following previous LASIK treatments. FEMTO LDV was used for flap creation in 85 previously LASIK-treated eyes of 62 patients. The intended flap thickness was 90 μm in 81 eyes and 140 μm in 4 eyes. The size of the suction ring was 9.0 mm in 72 eyes and 9.5 mm in 13 eyes. Flap dimensions were measured and correlated to preoperative characteristics. With the intended flap thickness of 90 μm in previously LASIK-treated eyes, the actual flap thickness was 90.2 ± 6.6 μm (range 80-122), and the flap diameter was 9.2 ± 0.2 mm (range 8.7-9.9). The mean hinge length was 4.0 ± 0.2 mm (range 3.0-4.8). Flap thickness correlated positively with patient age and hinge length. Complications were reported in 12 eyes (14.1 %). Most of the complications were very mild, and none of them prevented further refractive laser treatment. One eye lost two Snellen lines of best spectacle-corrected visual acuity. Femtosecond LASIK enhancement is warranted only in rare cases. Surgical experience is needed and special caution must be practiced. For cases of a primary free cap, femtosecond LASIK is not recommended.

  12. Laser processing of in situ TiN/Ti composite coating on titanium.

    Science.gov (United States)

    Sahasrabudhe, Himanshu; Soderlind, Julie; Bandyopadhyay, Amit

    2016-01-01

    Laser remelting of commercially pure titanium (CP-Ti) surface was done in a nitrogen rich inert atmosphere to form in situ TiN/Ti composite coating. Laser surface remelting was performed at two different laser powers of 425 W and 475 W. At each power, samples were fabricated with one or two laser scans. The resultant material was a nitride rich in situ coating that was created on the surface. The cross sections revealed a graded microstructure. There was presence of nitride rich dendrites dispersed in α-Ti matrix at the uppermost region. The structure gradually changed with lesser dendrites and more heat affected α-Ti phase maintaining a smooth interface. With increasing laser power, the dendrites appeared to be larger in size. Samples with two laser scans showed discontinuous dendrites and more α-Ti phase as compared to the samples with one laser scan. The resultant composite of TiN along with Ti2N in α-Ti showed substantially higher hardness and wear resistance than the untreated CP-Ti substrate. Coefficient of friction was also found to reduce due to surface nitridation. Leaching of Ti(4+) ions during wear test in DI water medium was found to reduce due to laser surface nitriding. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. 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.

  14. Characterization of the excimers of poly(N-vinylcarbazole) using TRANES

    International Nuclear Information System (INIS)

    Ghosh, Debanjana; Chattopadhyay, Nitin

    2011-01-01

    Time-resolved emission spectra (TRES) and time-resolved area normalized emission spectra (TRANES) are exploited to characterize the excimers of poly(N-vinylcarbazole) (PNVC) in toluene and water. The time-resolved study together with the steady state measurements, decipher the fluorescence of the system containing pendant carbazole moieties in the polymer backbone unambiguously. Isoemissive point in the TRANES establishes that there are only two excimers of PNVC, the partially overlapped excimer emitting at high energy and the sandwich type excimer emitting at lower energy, and they are formed exclusively in the photoexcited state. The study substantiates an equilibrium between the two excimers. - Graphical Abstract: Highlights: → TRES and TRANES are exploited to decipher the emission of PNVC in toluene and water. → The emission comes from two excimers: partially overlapped and sandwich type. → TRANES shows single isoemissive point establishing presence of two excimers only. → Sandwich excimer is formed from the partially overlapped one in the excited state. → Existence of an equilibrium is established.

  15. In-situ laser processing and microstructural characteristics of YBa2Cu3O7-δ thin films on Si with TiN buffer layer

    International Nuclear Information System (INIS)

    Tiwari, P.; Zheleva, T.; Narayan, J.

    1993-01-01

    The authors have prepared high-quality superconducting YBa 2 Cu 3 O 7 -δ (YBCO) thin films on Si(100) with TiN as a buffer layer using in-situ multitarget deposition system. Both TiN and YBCO thin films were deposited sequentially by KrF excimer laser ( | = 248 nm ) at substrate temperature of 650 C . Thin films were characterized using X-ray diffraction (XRD), four-point-probe ac resistivity, scanning electron microscopy (S E M), transmission electron microscopy (TEM), and Rutherford backscattering (RBS). The TiN buffer layer was epitaxial and the epitaxial relationship was found to be cube on cube with TiN parallel Si. YBCO thin films on Si with TiN buffer layer showed the transition temperature of 90-92K with T co (zero resistance temperature) of 84K. The authors have found that the quality of the buffer layer is very important in determining the superconducting transition temperature of the thin film. The effects of processing parameters and the correlation of microstructural features with superconducting properties are discussed in detail

  16. 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

  17. 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

  18. Laser plasmas as x-ray sources for lithographic imaging of submicron structures

    International Nuclear Information System (INIS)

    Bijkerk, F.; van Dorssen, G.E.; van der Wiel, M.J.

    1988-01-01

    Laser radiation can be used efficiently to generate x-rays for lithographic imaging of submicron patterns, e.g., for VLSI device fabrication. Due to their short wavelength and high average power, excimer lasers show much potential for this application. Results are presented of scaling studies for high repetition rate excimer laser application, using the frequency doubled output of a low repetition rate Nd:YAG/Glass laser. Spectral and spatial characteristics of x-ray emission of the laser plasma are shown. The power density in the laser focus was 3 x 10 12 W/cm 2 . With this source Si x-ray masks with submicron Au absorber profiles are imaged into high sensitivity x-ray photoresist. For the exposures 80 laser shots sufficed to yield high quality submicron structures. Extrapolation of the results to a high power excimer laser reduces the exposure time of the photoresists to several seconds, enabling a wafer throughput at an industrial level

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Refractive regression after laser in situ keratomileusis.

    Science.gov (United States)

    Yan, Mabel K; Chang, John Sm; Chan, Tommy Cy

    2018-04-26

    Uncorrected refractive errors are a leading cause of visual impairment across the world. In today's society, laser in situ keratomileusis (LASIK) has become the most commonly performed surgical procedure to correct refractive errors. However, regression of the initially achieved refractive correction has been a widely observed phenomenon following LASIK since its inception more than two decades ago. Despite technological advances in laser refractive surgery and various proposed management strategies, post-LASIK regression is still frequently observed and has significant implications for the long-term visual performance and quality of life of patients. This review explores the mechanism of refractive regression after both myopic and hyperopic LASIK, predisposing risk factors and its clinical course. In addition, current preventative strategies and therapies are also reviewed. © 2018 Royal Australian and New Zealand College of Ophthalmologists.

  5. Laser materials processing with diode lasers

    OpenAIRE

    Li, Lin; Lawrence, Jonathan; Spencer, Julian T.

    1996-01-01

    Laser materials processing is currently dominated by CO2, Nd-YAG and Excimer lasers. Continuous advances in semiconductor laser technology over the last decade have increased the average power output of the devices annualy by two fold, resulting in the commercial availability of the diode lasers today with delivery output powers in excess of 60W in CW mode and 5kW in qasi-CW mode. The advantages of compactness, high reliability, high efficiency and potential low cost, due to the mass producti...

  6. Laser applications in the electronics and optoelectronics industry in Japan

    Science.gov (United States)

    Washio, Kunihiko

    1999-07-01

    This paper explains current status and technological trends in laser materials processing applications in electronics and optoelectronics industry in Japan. Various laser equipment based on solid state lasers or gas lasers such as excimer lasers or CO2 lasers has been developed and applied in manufacturing electronic and optoelectronic devices to meet the strong demands for advanced device manufacturing technologies for high-performance, lightweight, low power-consumption portable digital electronic appliances, cellular mobile phones, personal computers, etc. Representative applications of solid-state lasers are, opaque and clear defects repairing of photomasks for LSIs and LCDs, trimming of thick-film chip resistors and low resistance metal resistors, laser cutting and drilling of thin films for high-pin count semiconductor CSP packages, laser patterning of thin-film amorphous silicon solar cells, and laser welding of electronic components such as hard-disk head suspensions, optical modules, miniature relays and lithium ion batteries. Compact and highly efficient diode- pumped and Q-switched solid-state lasers in second or third harmonic operation mode are now being increasingly incorporated in various laser equipment for fine material processing. Representative applications of excimer lasers are, sub-quarter micron design-rule LSI lithography and low- temperature annealing of poly-silicon TFT LCD.

  7. New laser research and development

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    New types of lasers must be developed to provide the desired energy per pulse, pulse length, pulse shape, wavelength, and efficiency for laser-fusion applications. This advanced laser research has focused on rare-gas oxides and on Hg 2 excimers

  8. 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)

  9. In situ detrital zircon (U-Th)/He thermochronology

    Science.gov (United States)

    Tripathy, A.; Monteleone, B. D.; van Soest, M. C.; Hodges, K.; Hourigan, J. K.

    2010-12-01

    situ method, utilizing SIMS to determine the U-Th concentrations. The major mode is the same as the conventional dataset, with only single outliers missing from the in situ dataset. The in situ method is described as follows: Zircons are polished and imaged using cathodoluminesence to guide laser spot placement. Then, each grain is ablated with a 193nm ArF Excimer laser using 20-35µm beam sizes and depths of 10-17µm. After purification, 4He is analyzed on a ThermoScientific Helix Split Flight Tube mass spectrometer. U-Th concentrations are measured on the polished mount using a Cameca IMS 6f by placing a 60µm diameter beam directly over the He laser pit to cover the surface area contributing to the measured He. In theory, using LA-ICP-MS to obtain U-Th concentrations could be a faster, cheaper, but possibly less precise, technique. However, using laser ablation would allow pit sizes that average the U-Th concentration over the volume of material available that contributes to the measured He, thus accounting for intracrystalline α-recoil effects. Preliminary data on slabs of Sri Lankan zircon suggest this could be a viable method, but will require further exploration and refinement.

  10. Tritium decontamination from co-deposited layer on tungsten substrate by ultra violet lamp and laser

    International Nuclear Information System (INIS)

    Oya, Yasuhisa; Tadokoro, Takahiro; Shu, Wataru; Hayashi, Takumi; O'hira, Shigeru; Nishi, Masataka

    2001-01-01

    Tritium decontamination using ultra violet (UV) lamp and laser was performed. Simulated co-deposited layer on tungsten substrate was deposited by C 2 H 2 or C 2 D 2 glow discharge. The co-deposited layer was irradiated to UV lights from a xenon excimer lamp (172 nm) or ArF excimer laser (193 nm) and the in-situ decontamination behavior was evaluated by a mass spectrometer. After the UV irradiation, the hydrogen concentration in the co-deposited layer was evaluated by elastic recoil detection analysis (ERDA) and the depth profile was analyzed by secondary ion mass spectrometry (SIMS). For the co-deposited layer formed by C 2 D 2 glow discharge, it was found that M/e 3 (HD) gas was released mainly during the UV lamp irradiation while both M/e 3 (HD) and M/e 4 (D 2 ) gases were detected during the UV laser irradiation. Though the co-deposited layer was not removed by UV lamp irradiation, almost all the co-deposited layer was removed by UV laser irradiation within 1 min. The ratio of hydrogen against carbon in the co-deposited layer was estimated to be 0.53 by ERDA and the number of photon needed for removing 1 μm thick co-deposited layer was calculated to be 3.7x10 18 cm -2 for the UV laser by SIMS measurement. It is concluded that C-H (C-D) bond on the co-deposited layer were dissociated by irradiation of UV lamp while the co-deposited layer itself was removed by the UV laser irradiation. (author)

  11. LASIK

    Medline Plus

    Full Text Available ... surgery, FDA’s current LASIK activities , and FDA-approved lasers for LASIK . LASIK stands for Laser-Assisted In Situ Keratomileusis and is a procedure ... the front of the eye, using an excimer laser. A mechanical microkeratome (a blade device) or a ...

  12. Phase evolution in calcium phosphate coatings obtained by in situ laser cladding

    International Nuclear Information System (INIS)

    Lv Xiaowei; Lin Xin; Hu Jiang; Gao Bo; Huang Weidong

    2012-01-01

    Calcium phosphate coating was fabricated by in situ laser cladding using mixed powders of CaCO 3 and CaHPO 4 , which presented a complex phase constitution since the reactions between CaCO 3 and CaHPO 4 would produce not only hydroxyapatite (HA) in the coating, but also other phases, such as Ca 4 (PO 4 ) 2 O (TTCP) and α-Ca 3 (PO 4 ) 2 (α-TCP). In order to realize the control of the phase constitution, the effects of the Ca/P molar ratio of mixed powders, laser power, scanning velocity and heat treatment on the phase constitution of the coatings were investigated through X-ray diffraction analysis. It is found that the variation of the Ca/P molar ratio of the mixed powders, laser power and scanning velocity can adjust, to a certain extent, the proportion of HA, α-TCP, and TTCP in the coating. However, the α-TCP and TTCP cannot be eliminated from the coating due to the intrinsic high cooling rate of the laser melt pool during laser cladding. By suitable post heat treatment, the TTCP and α-TCP in the coating can be partially or completely transformed into HA. Therefore, HA coating or coatings with desirable proportion of HA, α-TCP and TTCP can be obtained by in situ laser cladding plus post heat treatment. - Highlights: ► The phase constitution varies with the Ca/P molar ratio of the mixed powders of CaCO 3 and CaHPO 4 . ► High laser powder and scanning velocity are disadvantages for the synthesis of HA. ► Heat treatment with furnace cooling can make α-TCP and TTCP transform into HA.

  13. 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)

  14. Dry eye after laser in-situ keratomileusis.

    Science.gov (United States)

    Raoof, Duna; Pineda, Roberto

    2014-01-01

    Laser-assisted in-situ keratomileusis (LASIK) is one of the most commonly performed refractive procedures with excellent visual outcomes. Dry eye syndrome is one of the most frequently seen complications after LASIK, with most patients developing at least some mild dry eye symptoms postoperatively. To achieve improved visual outcomes and greater patient satisfaction, it is essential to identify patients prone to dry eyes preoperatively, and initiate treatment early in the course. Enhanced understanding of the pathophysiology of post-LASIK dry eye will help advance our approach to its management.

  15. 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.

  16. 193nm high power lasers for the wide bandgap material processing

    Science.gov (United States)

    Fujimoto, Junichi; Kobayashi, Masakazu; Kakizaki, Koji; Oizumi, Hiroaki; Mimura, Toshio; Matsunaga, Takashi; Mizoguchi, Hakaru

    2017-02-01

    Recently infrared laser has faced resolution limit of finer micromachining requirement on especially semiconductor packaging like Fan-Out Wafer Level Package (FO-WLP) and Through Glass Via hole (TGV) which are hard to process with less defect. In this study, we investigated ablation rate with deep ultra violet excimer laser to explore its possibilities of micromachining on organic and glass interposers. These results were observed with a laser microscopy and Scanning Electron Microscope (SEM). As the ablation rates of both materials were quite affordable value, excimer laser is expected to be put in practical use for mass production.

  17. Evaluation of the performance of small diode pumped UV solid state (DPSS) Nd:YAG lasers as new radiation sources for atmospheric pressure laser ionization mass spectrometry (APLI-MS).

    Science.gov (United States)

    Kersten, Hendrik; Lorenz, Matthias; Brockmann, Klaus J; Benter, Thorsten

    2011-06-01

    The performance of a KrF* bench top excimer laser and a compact diode pumped UV solid state (DPSS) Nd:YAG laser as photo-ionizing source in LC-APLI MS is compared. The commonly applied bench-top excimer laser, operating at 248 nm, provides power densities of the order of low MW/cm(2) on an illuminated area of 0.5 cm(2) (8 mJ/pulse, 5 ns pulse duration, beam waist area 0.5 cm(2), 3 MW/cm(2)). The DPSS laser, operating at 266 nm, provides higher power densities, however, on a two orders of magnitude smaller illuminated area (60 μJ/pulse, 1 ns pulse duration, beam waist area 2 × 10(-3) cm(2), 30 MW/cm(2)). In a common LC-APLI MS setup with direct infusion of a 10 nM pyrene solution, the DPSS laser yields a significantly smaller ion signal (0.9%) and signal to noise ratio (1.4%) compared with the excimer laser. With respect to the determined low detection limits (LODs) for PAHs of 0.1 fmol using an excimer laser, LODs in DPSS laser LC-APLI MS in the low pmol regime are expected. The advantages of the DPSS laser with respect to applicability (size, cost, simplicity) may render this light source the preferred one for APLI applications not focusing on ultimately high sensitivities. Furthermore, the impact of adjustable ion source parameters on the performance of both laser systems is discussed in terms of the spatial sensitivity distribution described by the distribution of ion acceptance (DIA) measurements. Perspectives concerning the impact on future APLI-MS applications are given.

  18. Small Incision Lenticule Extraction (SMILE) vs. Femtosecond Laser in Situ Keratomileusis (FS-LASIK) for treatment of myopia

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Justesen, Birgitte

    Purpose: - 67 ord LASIK has been the dominating corneal refractive procedure for almost two decades, but the new flap-free SMILE procedure has shown promising results. The aim of this study was to evaluate and compare refractive predictability, uncorrected and corrected distance visual acuity (UDVA...... and CDVA), and safety at 1 day, 1 week and 3 months after SMILE and FS-LASIK for all degrees of myopia, but in particular high myopia. Setting: Department of Ophthalmology, Odense University Hospital, Odense, Denmark Methods: - 157 ord Retrospective study of results after SMILE and FS-LASIK for all degrees...... having undergone re-treatment. The SMILE treatments and FS-LASIK flaps were performed with a VisuMax® femtosecond laser (Carl Zeiss-Meditec, Jena, Germany). The FS-LASIK photoablation was performed with a MEL-80 flying-spot excimer laser with eye-tracker (Carl Zeiss-Meditec, Jena, Germany). In SMILE...

  19. 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

  20. Ablation of polymers by ultraviolet pulsed laser

    International Nuclear Information System (INIS)

    Brezini, A.; Benharrats, N.

    1993-08-01

    The surface modifications of different polymers treated by far UV-Excimer laser (λ = 193mn, 248, 308nm) are analysed by X-Ray Photoelectrons Spectroscopy. The main feature observed depends strongly on the absorption coefficients. For the high absorbing polymers such (PVC, PS, PI,...) the mechanism of the UV-Excimer Laser interaction appears to be governed by an ablative photodecomposition process (APD) with an APD threshold. In the other limit, i.e. low absorbing polymer the interaction leads to a photothermal process. (author). 51 refs, 24 figs, 7 tabs

  1. In situ optoacoustic measurement of the pointing stability of femtosecond laser beams

    Science.gov (United States)

    Pushkarev, D.; Mitina, E.; Uryupina, D.; Volkov, R.; Karabytov, A.; Savel'ev, A.

    2018-02-01

    A new method for the in situ acoustic measurement of the beam pointing stability (BPS) of powerful pulsed lasers is tested. A broadband (~6 MHz) piezoelectric transducer placed a few millimeters from the laser spark produces an electric pulse. We show that variation in time of the position of this pulse can be used to assess the BPS down to 1 µrad in a few hundred laser shots. The estimated value coincides well with the BPS estimated using standard measurement in the far field.

  2. Configuration of organic dye excimers in nanoporous SiO2 matrices

    International Nuclear Information System (INIS)

    Sorokin, A.V.; Gnap, B.A.; Bespalova, I.I.; Yefimova, S.L.; Malyukin, Yu.V.

    2016-01-01

    The effect of cyanine dye 3,3′-dioctadecyloxacarbocyanine perchlorate (DiO) and benzimidazole dye 4-dimethylamino-1,8-naphthoylene-1′,2′-benzimidazole (DNBI) accumulation in nanoporous silica matrices on the dyes luminescence properties has been studied. For both dyes, ground state dimer formation with perpendicular transition dipoles at high dye concentrations has been considered as a result of restricted geometry of the nanoscale pores. The dimer excitation leads to excimer formation revealing by appearance of new long-wavelength luminescence band and shortening the dye luminescence lifetime. In the excimer luminescence excitation spectra two additional bands have been observed, one of which is bathochromically shifted relatively to the absorption band and another one is hypsocromically shifted. Using the Kasha exciton model it was shown that the excimers possess oblique transition dipoles configuration. - Highlights: • Organic dye molecules are efficiently accumulated in nanoporous silica matrices. • Restricted geometry of SiO 2 nanopores provokes excimerization of both cyanine and benzimidazole dyes. • The excimers reveal configuration of oblique dimers. • The excimers are originated from ground state dimers with a perpendicular arrangement of transition dipoles.

  3. 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.

  4. 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.

  5. In-situ sequential laser transfer and laser reduction of graphene oxide films

    Science.gov (United States)

    Papazoglou, S.; Petridis, C.; Kymakis, E.; Kennou, S.; Raptis, Y. S.; Chatzandroulis, S.; Zergioti, I.

    2018-04-01

    Achieving high quality transfer of graphene on selected substrates is a priority in device fabrication, especially where drop-on-demand applications are involved. In this work, we report an in-situ, fast, simple, and one step process that resulted in the reduction, transfer, and fabrication of reduced graphene oxide-based humidity sensors, using picosecond laser pulses. By tuning the laser illumination parameters, we managed to implement the sequential printing and reduction of graphene oxide flakes. The overall process lasted only a few seconds compared to a few hours that our group has previously published. DC current measurements, X-Ray Photoelectron Spectroscopy, X-Ray Diffraction, and Raman Spectroscopy were employed in order to assess the efficiency of our approach. To demonstrate the applicability and the potential of the technique, laser printed reduced graphene oxide humidity sensors with a limit of detection of 1700 ppm are presented. The results demonstrated in this work provide a selective, rapid, and low-cost approach for sequential transfer and photochemical reduction of graphene oxide micro-patterns onto various substrates for flexible electronics and sensor applications.

  6. [Incidence of vitreoretinal pathologic conditions in myopic eyes after laser in situ keratomileusis].

    Science.gov (United States)

    Lin, Jijian; Xie, Xin; Du, Xinhua; Yang, Yabo; Yao, Ke

    2002-09-01

    To determine the incidence of vitreoretinal pathologic conditions in myopic eyes after laser in situ keratomileusis. Vitreoretinal pathologic conditions of 1981 consecutive eyes (995 patients) having undergone laser-assisted in situ keratomileusis for the correction of myopia were studied. Preoperative and postoperative basic examinations included visual acuity, manifest and cycloplegic refraction, slit-lamp microscope examination, applanation tonometry and a fundus examination after pupil dilatation by indirect ophthalmoscopy and biomicroscopy with spherical lens of + 90 diopters. Before laser in situ keratomileusis, preventive treatment was carried out for predisposing lesion of retinal detachment in 8 eyes: 6 eyes for lattice degeneration and 2 eyes for atrophic holes. Postoperative examinations were conducted at 1, 3 and 12 months and once a year thereafter. All eyes were followed up for >/= 12 months. Eyes were followed for a mean of (18.40 +/- 4.50) months (range 12 - 28) after the surgery. Sixteen eyes of 13 patients (0.81%) developed vitreoretinopathy after LASIK, including 6 eyes with lattice degeneration (0.30%) in which one of them had previous laser treatment, 2 with posterior vitreous detachment (0.10%), 2 with macular hemorrhage (0.10%), 4 with rhegmatogenous retinal detachment (0.20%), and 2 with retinal tear without retinal detachment (0.10%) in which one of them had previous laser treatment for lattice degeneration. Five patients were males (5 eyes involved). Others were females. Mean age of the group with vitreoretinal pathologic conditions was 31.80 +/- 5.85 years (range 22 to 43). The interval between refractive surgery and development of vitreoretinal complication was (10.38 +/- 6.20) months (range 1 to 24). The eyes that developed vitreoretinopathy had myopia -4.75 to -15.00 diopters (mean -9.45 +/- 2.61 D) before LASIK. The comparison of incidences of vitreoretinopathy after LASIK between the group of >/= -6.00 D and lattice degeneration and

  7. Nd:YAG laser for epithelial ingrowth after laser in situ keratomileusis.

    Science.gov (United States)

    Mohammed, Osama Ali; Mounir, Amr; Hassan, Amin Aboali; Alsmman, Alahmady Hamad; Mostafa, Engy Mohamed

    2018-05-04

    To evaluate the efficacy of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser for treatment of epithelial ingrowth after laser in situ keratomileusis (LASIK). Fifty-eight patients with epithelial ingrowth presented to Sohag refractive center, Sohag, Egypt, between January 2015 and March 2017. Only 41 patients (18 females and 23 males, mean age: 33.4 years) involving 41 eyes were indicated for treatment by Nd:YAG laser as the rest of the eyes were only under observation. Patients with epithelial ingrowth were recognized at a mean of 6 months after primary LASIK procedure (range: 2-16 months). Four eyes had undergone previous LASIK enhancements. Four eyes had the epithelial ingrowth removed by flap lift and scrapping. The mean intensity of the spots used was 0.8 mJ with variable number of shots depending on the size and density of the epithelial ingrowth area. Twenty-eight eyes showed complete regression after one session, while the rest necessitated 2-3 sessions for complete resolution. Mean follow-up period was 8 months (range 5-12 months). Epithelial ingrowth was treated successfully in all 41 eyes. The uncorrected visual acuities were 20/20, and there was no evidence of recurrent epithelial ingrowth after 6 months with no complications reported. YAG laser is a simple, effective outpatient procedure for the management of epithelial ingrowth after LASIK.

  8. 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.

  9. Excimer Formation Dynamics of Dipyrenyldecane in Structurally Different Ionic Liquids.

    Science.gov (United States)

    Yadav, Anita; Pandey, Siddharth

    2017-12-07

    Ionic liquids, being composed of ions alone, may offer alternative pathways for molecular aggregation. These pathways could be controlled by the chemical structure of the cation and the anion of the ionic liquids. Intramolecular excimer formation dynamics of a bifluorophoric probe, 1,3-bis(1-pyrenyl)decane [1Py(10)1Py], where the fluorophoric pyrene moieties are separated by a long decyl chain, is investigated in seven different ionic liquids in 10-90 °C temperature range. The long alkyl separator allows for ample interaction with the solubilizing milieu prior to the formation of the excimer. The ionic liquids are composed of two sets, one having four ionic liquids of 1-butyl-3-methylimidazolium cation ([bmim + ]) with different anions and the other having four ionic liquids of bis(trifluoromethylsulfonyl)imide anion ([Tf 2 N - ]) with different cations. The excimer-to-monomer emission intensity ratio (I E /I M ) is found to increase with increasing temperature in sigmoidal fashion. Chemical structure of the ionic liquid controls the excimer formation efficiency, as I E /I M values within ionic liquids with the same viscosities are found to be significantly different. The excited-state intensity decay kinetics of 1Py(10)1Py in ionic liquids do not adhere to a simplistic Birk's scheme, where only one excimer conformer forms after excitation. The apparent rate constants of excimer formation (k a ) in highly viscous ionic liquids are an order of magnitude lower than those reported in organic solvents. In general, the higher the viscosity of the ionic liquid, the more sensitive is the k a to the temperature with higher activation energy, E a . The trend in E a is found to be similar to that for activation energy of the viscous flow (E a,η ). Stokes-Einstein relationship is not followed in [bmim + ] ionic liquids; however, with the exception of [choline][Tf 2 N], it is found to be followed in [Tf 2 N - ] ionic liquids suggesting the cyclization dynamics of 1Py(10)1Py

  10. 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

  11. Impact of in situ polymer coating on particle dispersion into solid laser-generated nanocomposites.

    Science.gov (United States)

    Wagener, Philipp; Brandes, Gudrun; Schwenke, Andreas; Barcikowski, Stephan

    2011-03-21

    The crucial step in the production of solid nanocomposites is the uniform embedding of nanoparticles into the polymer matrix, since the colloidal properties or specific physical properties are very sensitive to particle dispersion within the nanocomposite. Therefore, we studied a laser-based generation method of a nanocomposite which enables us to control the agglomeration of nanoparticles and to increase the single particle dispersion within polyurethane. For this purpose, we ablated targets of silver and copper inside a polymer-doped solution of tetrahydrofuran by a picosecond laser (using a pulse energy of 125 μJ at 33.3 kHz repetition rate) and hardened the resulting colloids into solid polymers. Electron microscopy of these nanocomposites revealed that primary particle size, agglomerate size and particle dispersion strongly depend on concentration of the polyurethane added before laser ablation. 0.3 wt% polyurethane is the optimal polymer concentration to produce nanocomposites with improved particle dispersion and adequate productivity. Lower polyurethane concentration results in agglomeration whereas higher concentration reduces the production rate significantly. The following evaporation step did not change the distribution of the nanocomposite inside the polyurethane matrix. Hence, the in situ coating of nanoparticles with polyurethane during laser ablation enables simple integration into the structural analogue polymer matrix without additives. Furthermore, it was possible to injection mold these in situ-stabilized nanocomposites without affecting particle dispersion. This clarifies that sufficient in situ stabilization during laser ablation in polymer solution is able to prevent agglomeration even in a hot polymer melt.

  12. Laser in operative dentistry

    Directory of Open Access Journals (Sweden)

    E. Yasini

    1994-06-01

    Full Text Available Today laser has a lot of usage in medicine and dentistry. In the field of dentistry, laser is used in soft tissue surgery, sterilization of canals (in root canal therapy and in restorative dentistry laser is used for cavity preparation, caries removal, sealing the grooves (in preventive dentistry, etching enamel and dentin, composite polymerization and removal of tooth sensitivity. The use of Co2 lasers and Nd: YAG for cavity preparation, due to creating high heat causes darkness and cracks around the region of laser radiation. Also due to high temperature of these lasers, pulp damage is inevitable. So today, by using the Excimer laser especially the argon floride type with a wavelength of 193 nm, the problem of heat stress have been solved, but the use of lasers in dentistry, especially for cavity preparation needs more researches and evaluations.

  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. 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

  15. 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

  16. Stability of iodinated contrast media in UV-laser irradiation and toxicity of photoproducts

    International Nuclear Information System (INIS)

    Groenewaeller, E.F.; Kehlbach, R.; Claussen, C.D.; Duda, S.H.; Wahl, H.G.; Rodemann, H.P.

    1998-01-01

    Purpose: In XeCl-Excimer laser angioplasty, unintended and possibly harmful interaction of the UV-laser light and the contrast media may occur due to the high concentration of contrast medium proximal to the occlusion or subtotal stenosis. Methods: One ml of three nonionic monomeric contrast agents (iopromide, iomeprol, iopamidol), one nonionic dimetric (jotrolane), and one ionic monomeric (amidotrizoate) X-ray contrast agent were irradiated with a XeCl excimer laser (λ=308 nm, pulse duration 120 ns, 50 Hz) using a 9 French multifiber catheter (12 sectors). Up to 20 000 pulses (106 J) were applied. Using high performance liquid chromatography the amount of liberated iodide as well as the fraction of unchanged contrast media were measured. Cytotoxicity of the photoproducts was tested in a colony formation assay of human skin fibroblasts. The contrast agents were irradiated with 2000 pulses/ml (5.3 mJ/pulse; 10.6 J) and then added to the cell cultures for a period of three hours in a concentration of 10%. Results: Excimer laser irradiation induced iodide liberation of up to 3.3 mg iodide/ml. Up to 19% of the contrast agents changed their original molecular structure. Incubation of irradiated contrast agents resulted in a significantly decreased potential for colony formation (p values ranging from 0.0044 to 0.0102) with significantly higher toxicity of amidotrizoate and iomeprol in comparison to iopromide, iotrolan, and iopamidol. Discussion: Due to the cytotoxic photoproducts and the high level of liberated iodide, it is recommended to flush the artery with physiological saline solution before applying a pulsed excimer laser in human arterial obstructions in order to reduce the contrast agent concentration at the site of irradiation. (orig.) [de

  17. 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)

  18. 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.

  19. Fibrinous anterior uveitis following laser in situ keratomileusis

    Directory of Open Access Journals (Sweden)

    Parmar Pragya

    2009-01-01

    Full Text Available A 29-year-old woman who underwent laser in situ keratomileusis (LASIK for myopic astigmatism in both eyes presented with severe pain, photophobia and decreased visual acuity in the left eye eight days after surgery. Examination revealed severe anterior uveitis with fibrinous exudates in the anterior chamber, flap edema and epithelial bullae. Laboratory investigations for uveitis were negative and the patient required systemic and intensive topical steroids with cycloplegics to control the inflammation. This case demonstrates that severe anterior uveitis may develop after LASIK and needs prompt and vigorous management for resolution.

  20. On the origin of excimer emission in electroluminescence and photoluminescence spectra of polyfluorenes

    International Nuclear Information System (INIS)

    Vacha, Martin; Ha, Jaekook; Sato, Hisaya

    2007-01-01

    We report a study on the differences in red-shifted excimer band in photoluminescence (PL) and electroluminescence (EL) spectra of thin films of a copolymer of dibutylfluorene and butylphenylphenoxazine. The relative intensity of the excimer band in PL spectra increases with temperature above the polymer glass transition, and with the intensity of the excitation light. In EL spectra, on the other hand, the relative excimer intensity is seen to decrease with increasing driving voltage. These opposite trends originate from the different nature of excitations in PL and EL spectra: photoexcitation directly creates singlet excitons while electric excitation proceeds via interaction of injected electrons and holes. In case of electric excitation, the observed results might be due to trap-assisted excimer formation

  1. 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

  2. FY 1997 report on the study on cryogenic aggregate target PLD process by multi-laser excitation for using gaseous materials; 1997 nendo chosa hokokusho (kitai genryo riyo no tame no taju laser reiki ni yoru gokuteion gyoshutai target PLD process ni kansuru kenkyu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    This paper reports the result in fiscal 1995 of the study on PLD (pulse laser deposition) thin film formation process having been made since 1993. In fiscal 1995, the effect of irradiation of excimer laser and YGA(SHG) on ablation of aggregates of N2, CH4, Ar, Kr and Xe, and the effect of time-delayed irradiation of YGA(SHG) and KrF excimer laser on ablation of N2 aggregate were studied aiming at exciting ablation by cryogenic aggregate alone. Experimental results by a newly developed multi-laser excitation experiment equipment are as follows. Ablation was not caused by KrF excimer laser irradiation, while caused by YGA(SHG) irradiation. Ablation was caused by 1mm thick N2 or CH4 aggregate alone. Kr target was the most promising among rare gas solid targets expected as seed of ablation occurrence. Multi-irradiation showed a different ablation behavior as compared with single YGA(SHG) irradiation, and in some cases, multi-irradiation not increased scattering of particles. Time-delayed multi- irradiation (YGA(SHG) excitation after excimer excitation) was effective. 23 figs., 4 tabs.

  3. Effect of pulsed laser parameters on in-situ TiC synthesis in laser surface treatment

    Science.gov (United States)

    Hamedi, M. J.; Torkamany, M. J.; Sabbaghzadeh, J.

    2011-04-01

    Commercial titanium sheets pre-coated with 300-μm thick graphite layer were treated by employing a pulsed Nd:YAG laser in order to enhance surface properties such as wear and erosion resistance. Laser in-situ alloying method produced a composite layer by melting the titanium substrate and dissolution of graphite in the melt pool. Correlations between pulsed laser parameters, microstructure and microhardness of the synthesized composite coatings were investigated. Effects of pulse duration and overlapping factor on the microstructure and hardness of the alloyed layer were deduced from Vickers micro-indentation tests, XRD, SEM and metallographic analyses of cross sections of the generated layer. Results show that the composite cladding layer was constituted with TiC intermetallic phase between the titanium matrix in particle and dendrite forms. The dendritic morphology of composite layer was changed to cellular grain structure by increasing laser pulse duration and irradiated energy. High values of the measured hardness indicate that deposited titanium carbide increases in the conditions with more pulse duration and low process speed. This occurs due to more dissolution of carbon into liquid Ti by heat input increasing and positive influence of the Marangoni flow in the melted zone.

  4. Pulsed UV laser technologies for ophthalmic surgery

    International Nuclear Information System (INIS)

    Razhev, A M; Bagayev, S N; Churkin, D S; Kargapol’tsev, E S; Chernykh, V V; Iskakov, I A; Ermakova, O V

    2017-01-01

    The paper provides an overview of the results of multiyear joint researches of team of collaborators of Institute of Laser Physics SB RAS together with NF IRTC “Eye Microsurgery” for the period from 1988 to the present, in which were first proposed and experimentally realized laser medical technologies for correction of refractive errors of known today as LASIK, the treatment of ophthalmic herpes and open-angle glaucoma. It is proposed to carry out operations for the correction of refractive errors the use of UV excimer KrCl laser with a wavelength of 222 nm. The same laser emission is the most suitable for the treatment of ophthalmic herpes, because it has a high clinical effect, combined with many years of absence of recrudescence. A minimally invasive technique of glaucoma operations using excimer XeCl laser (λ=308 nm) is developed. Its wavelength allows perform all stages of glaucoma operations, while the laser head itself has high stability and lifetime, will significantly reduce operating costs, compared with other types of lasers. (paper)

  5. 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.

  6. Mass-Selective Laser Photoionization.

    Science.gov (United States)

    Smalley, R. E.

    1982-01-01

    Discusses the nature and applications of mass-selective laser photoionization. The ionization can be done with a single intense laser pulse lasting a few billionths of a second with no molecular fragmentation. Applications focus on: (1) benzene clusters, excimers, and exciplexes; (2) metal clusters; and (3) triplet formation and decay. (Author/JN)

  7. Laser annealed HWCVD and PECVD thin silicon films. Electron field emission

    International Nuclear Information System (INIS)

    O'Neill, K.A.; Shaikh, M.Z.; Lyttle, G.; Anthony, S.; Fan, Y.C.; Persheyev, S.K.; Rose, M.J.

    2006-01-01

    Electron Field Emission (FE) properties of various laser annealed thin silicon films on different substrates were investigated. HWCVD microcrystalline and PECVD amorphous silicon films were irradiated with Nd : YAG and XeCl Excimer lasers at varying energy densities. Encouraging FE results were mainly from XeCl Excimer laser processed PECVD and HWCVD films on metal backplanes. FE measurements were complemented by the study of film surface morphology. Geometric field enhancement factors from surface measurements and Fowler-Nordheim Theory (FNT) were compared. FE properties of the films were also found to be particularly influenced by the backplane material

  8. [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.

  9. Effect of UV laser irradiation on tissue

    International Nuclear Information System (INIS)

    Nakayama, Takeyoshi; Kubo, Uichi

    1992-01-01

    Laser-tissue interactions have been investigated through Electron Probe Micro Analysis (EPMA), UV-visible optical absorption and Fourier Transform Infrared Spectroscopy (FTIR). Three excimer lasers, ArF, KrF and XeCl, were used to irradiate tissue; cow thighbone and gelatin thin film. Features of UV laser irradiation are described. (author)

  10. 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.

  11. 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.

  12. Organelle-specific injury to melanin-containing cells in human skin by pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, G.F.; Shepard, R.S.; Paul, B.S.; Menkes, A.; Anderson, R.R.; Parrish, J.A.

    1983-12-01

    Physical models predict that ultraviolet laser radiation of appropriately brief pulses can selectively alter melanin-containing cellular targets in human skin. Skin of normal human volunteers was exposed to brief (20 nanosecond) 351-nm wave length pulses from a XeF excimer laser, predicting that those cells containing the greatest quantities of melanized melanosomes (lower half of the epidermis) would be selectively damaged. Transmission electron microscopy revealed the earliest cellular alteration to be immediate disruption of melanosomes, both within melanocytes and basal keratinocytes. This disruption was dose dependent and culminated in striking degenerative changes in these cells. Superficial keratinocytes and Langerhans cells were not affected. It was concluded that the XeF excimer laser is capable of organelle-specific injury to melanosomes. These findings may have important clinical implications in the treatment of both benign and malignant pigmented lesions by laser radiations of defined wave lengths and pulse durations.

  13. Quantitative Potassium Measurements with Laser-Induced Breakdown Spectroscopy Using Low-Energy Lasers: Application to In Situ K-Ar Geochronology for Planetary Exploration.

    Science.gov (United States)

    Cho, Yuichiro; Horiuchi, Misa; Shibasaki, Kazuo; Kameda, Shingo; Sugita, Seiji

    2017-08-01

    In situ radiogenic isotope measurements to obtain the absolute age of geologic events on planets are of great scientific value. In particular, K-Ar isochrons are useful because of their relatively high technical readiness and high accuracy. Because this isochron method involves spot-by-spot K measurements using laser-induced breakdown spectroscopy (LIBS) and simultaneous Ar measurements with mass spectrometry, LIBS measurements are conducted under a high vacuum condition in which emission intensity decreases significantly. Furthermore, using a laser power used in previous planetary missions is preferable to examine the technical feasibility of this approach. However, there have been few LIBS measurements for K under such conditions. In this study, we measured K contents in rock samples using 30 mJ and 15 mJ energy lasers under a vacuum condition (10 -3  Pa) to assess the feasibility of in situ K-Ar dating with lasers comparable to those used in NASA's Curiosity and Mars 2020 missions. We obtained various calibration curves for K using internal normalization with the oxygen line at 777 nm and continuum emission from the laser-induced plasma. Experimental results indicate that when K 2 O laser energy, with a detection limit of 88 ppm and 20% of error at 2400 ppm of K 2 O. Futhermore, the calibration curve based on the K 769 nm line intensity normalized with continuum emission yielded the best result for the 15 mJ laser, giving a detection limit of 140 ppm and 20% error at 3400 ppm K 2 O. Error assessments using obtained calibration models indicate that a 4 Ga rock with 3000 ppm K 2 O would be measured with 8% (30 mJ) and 10% (15 mJ) of precision in age when combined with mass spectrometry of 40 Ar with 10% of uncertainty. These results strongly suggest that high precision in situ isochron K-Ar dating is feasible with a laser used in previous and upcoming Mars rover missions.

  14. Role of dual-laser ablation in controlling the Pb depletion in epitaxial growth of Pb(Zr0.52Ti0.48)O3 thin films with enhanced surface quality and ferroelectric properties

    Science.gov (United States)

    Mukherjee, Devajyoti; Hyde, Robert; Mukherjee, Pritish; Srikanth, Hariharan; Witanachchi, Sarath

    2012-03-01

    Pb depletion in Pb(Zr0.52Ti0.48)O3 (PZT) thin films has remained as a major setback in the growth of defect-free PZT thin films by pulsed laser ablation techniques. At low excimer (KrF) laser fluences, the high volatility of Pb in PZT leads to non-congruent target ablation and, consequently, non-stoichiometric films, whereas, at high laser fluences, the inherent ejection of molten droplets from the target leads to particulate laden films, which is undesirable in heterostructure growth. To overcome these issues, a dual-laser ablation (PLDDL) process that combines an excimer (KrF) laser and CO2 laser pulses was used to grow epitaxial PZT films on SrTiO3 (100) and MgO (100) substrates. Intensified-charge-coupled-detector (ICCD) images and optical emission spectroscopy of the laser-ablated plumes in PLDDL revealed a broader angular expansion and enhanced excitation of the ablated species as compared to those for single-laser ablation (PLDSL). This led to the growth of particulate-free PZT films with higher Pb content, better crystallinity, and lower surface roughness as compared to those deposited using PLDSL. For FE measurements, PZT capacitors were fabricated in situ using the latticed-matched metallic oxide, La0.7Sr0.3MnO3, as the top and bottom electrodes. PZT films deposited using PLDDL exhibited enhanced polarization for all driving voltages as compared to those deposited using PLDSL. A highest remanent polarization (Pr) of ˜91 μC/cm2 and low coercive field of ˜40 kV/cm was recorded at 9 V driving voltage. Fatigue characterization revealed that PZT films deposited using PLDDL showed unchanging polarization, even after 109 switching cycles.

  15. On the ex situ and in situ doping of refractory Ta by pulsed laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.L.; Lin, S.S.; Shen, P. [National Sun Yat-sen University, Department of Materials and Optoelectronic Science, Kaohsiung, Taiwan (China); Chen, S. [I-Shou University, Department of Mechanical and Automation Engineering, Kaohsiung, Taiwan (China)

    2017-06-15

    Ex situ and in situ doping processes of refractory Ta were accomplished by pulsed laser ablation of bulk Ta in vacuum with C-O-H supply from C-coated collodion film and within tetraethyl orthosilicate (TEOS), respectively. Analytical electron microscopic observations of the resultant particulates and condensates indicated that the former process involved interdiffusion in the condensed state to form two kinds of core-shell structures, i.e., C-O-H doped Ta with α-type (bcc) core and lamellar shell and O-H doped γ-TaC{sub 1-x} with amorphous Ta-C-O-H surrounding, respectively, for potential wear and lubrication applications at high temperatures. In situ TEOS mediation, however, enhanced solute trapping to form Si-C-O-H overdoped α-Ta with significant tetragonality (c/a ratio up to 1.27) and Si-O-H doped γ-TaC{sub 1-x} with {111}{sub γ} twin/fault and occasional epitaxial relationship [ anti 123]{sub α}//[ anti 112]{sub γ}; (121){sub α}//(anti 11 anti 1){sub γ} due to particle coalescence. Such Si-C-O-H mediated Ta particles may have potential optocatalytic applications. (orig.)

  16. Optimization of laser scribing for thin-film PV modules. Final technical progress report, 12 April 1995--11 October 1997

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A.D.; Matulionis, I.; Nakade, S. [Univ. of Toledo, OH (United States)

    1998-06-01

    This report covers the work done by the University of Toledo under this subcontract. Researchers determined the threshold power densities for the onset of ablation from thin films of CdTe, CuInSe{sub 2}, SnO{sub 2}:F, ZnO:Al, gold, and molybdenum for 12 different wavelength laser systems using wide variations of laser pulse durations. Optimum energy density for the most efficient removal of material during scribing strongly depends on the wavelength of the laser and, to a smaller extent, on the pulse duration. The optimum energy densities range from 0.5 J/sq cm for the 532-nm, 8-nsec YAG pulse on CdTe to 0.2 J/sq cm for the excimer laser at 308 nm on CIS. Poor scribing of CdTe was seen with the 1064-nm beam, ZnO was scribed poorly by all lasers except for the excimer laser. Excellent scribe profiles were observed with the 308-nm excimer lasers on all materials including ZnO.

  17. Phenylethynylpyrene excimer forming hybridization probes for fluorescence SNP detection

    DEFF Research Database (Denmark)

    Prokhorenko, Igor A.; Astakhova, Irina V.; Momynaliev, Kuvat T.

    2009-01-01

    Excimer formation is a unique feature of some fluorescent dyes (e.g., pyrene) which can be used for probing the proximity of biomolecules. Pyrene excimer fluorescence has previously been used for homogeneous detection of single nucleotide polymorphism (SNP) on DNA. 1-Phenylethynylpyrene (1-1-PEPy...

  18. Applications of lasers and electro-optics

    International Nuclear Information System (INIS)

    Tan, B.C.; Low, K.S.; Chen, Y.H.; Harith bin Ahmad; Tou, T.Y.

    1994-01-01

    Supported by the IRPA Programme on Laser Technology and Applications, many types of lasers have been designed, constructed and applied in various areas of science, medicine and industries. Amongst these lasers constructed were high power carbon dioxide lasers, rare gas halide excimer lasers, solid state Neodymium-YAG lasers, nitrogen lasers, flashlamp pumped dye lasers and nitrogen and excimer laser pumped dye lasers. These lasers and the associated electro-optics system, some with computer controlled, are designed and developed for the following areas of applications: 1. Industrial applications of high power carbon dioxide lasers for making of i.c. components and other materials processing purposes. Prototype operational systems have been developed. 2. Medical applications of lasers for cancer treatment using the technique of photodynamic therapy. A new and more effective treatment protocol has been proposed. 3. Agricultural applications of lasers in palm oil and palm fruit-fluorescence diagnostic studies. Fruit ripeness signature has been developed and palm oil oxidation level were investigated. 4. Development of atmospheric pollution monitoring systems using laser lidar techniques. Laboratory scale systems were developed. 5. Other applications of lasers including laser holographic and interferometric methods for the non destructive testing of materials. The activities of the group (from 1988-1990) have resulted in the submission of a patent for a laser device, publication of many research paper sin local and overseas journals and conference proceedings, completion of 1 Ph.D. dissertation and 6 M. Phil theses. Currently (1991), a total of 3 Ph.D., 6 M. Phil research programmes are involved in this research and development programme

  19. Facile synthesis of AgCl/polydopamine/Ag nanoparticles with in-situ laser improving Raman scattering effect

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Zhang, Wenqi; Wang, Lin; Wang, Feng, E-mail: wangfeng@shnu.edu.cn; Yang, Haifeng

    2017-01-15

    Highlights: • AgCl/PDA/AgNPs (polydopamine (PDA) adlayer covered cubic AgCl core inlaid with Ag nanoparticles (AgNPs)) was fabricated for in-situ SERS detection. • Such SERS substrate shows in-situ laser improving Raman scattering effect due to the generation of more AgNPs. • Enhancement factor could reach 10{sup 7}. • Such SERS substrate shows good reproducibility and long term stability. - Abstract: We reported a simple and fast method to prepare a composite material of polydopamine (PDA) adlayer covered cubic AgCl core, which was inlaid with Ag nanoparticles (NPs), shortly named as AgCl/PDA/AgNPs. The resultant AgCl/PDA/AgNPs could be employed as surface-enhanced Raman scattering (SERS) substrate for in-situ detection and the SERS activity could be further greatly improved due to the production of more AgNPs upon laser irradiation. With 4-mercaptopyridine (4-Mpy) as the probe molecule, the enhancement factor could reach 10{sup 7}. Additionally, such SERS substrate shows good reproducibility with relative standard deviation of 7.32% and long term stability (after storage for 100 days under ambient condition, SERS intensity decay is less than 25%). In-situ elevating SERS activity of AgCl/PDA/AgNPs induced by laser may be beneficial to sensitive analysis in practical fields.

  20. The Potassium-Argon Laser Experiment (KArLE): In Situ Geochronology for Planetary Robotic Missions

    Science.gov (United States)

    Cohen, Barbara

    2016-01-01

    The Potassium (K) - Argon (Ar) Laser Experiment (KArLE) will make in situ noble-gas geochronology measurements aboard planetary robotic landers and roverss. Laser-Induced Breakdown Spectroscopy (LIBS) is used to measure the K abun-dance in a sample and to release its noble gases; the evolved Ar is measured by mass spectrometry (MS); and rela-tive K content is related to absolute Ar abundance by sample mass, determined by optical measurement of the ablated volume. KArLE measures a whole-rock K-Ar age to 10% or better for rocks 2 Ga or older, sufficient to resolve the absolute age of many planetary samples. The LIBS-MS approach is attractive because the analytical components have been flight proven, do not require further technical development, and provide complementary measurements as well as in situ geochronology.

  1.   In situ identification of streptococci and other bacteria in initial dental biofilm by confocal laser scanning microscopy and fluorescence in situ hybridization

    DEFF Research Database (Denmark)

    Dige, Irene; Kilian, Mogens; Nilsson, Holger

    2007-01-01

    Confocal laser scanning microscopy (CLSM) has been employed as a method for studying intact natural biofilm. When combined with fluorescence in situ hybridization (FISH) it is possible to analyze spatial relationships and changes of specific members of microbial populations over time. The aim...

  2. 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

  3. Laser etching of polymer masked leadframes

    Science.gov (United States)

    Ho, C. K.; Man, H. C.; Yue, T. M.; Yuen, C. W.

    1997-02-01

    A typical electroplating production line for the deposition of silver pattern on copper leadframes in the semiconductor industry involves twenty to twenty five steps of cleaning, pickling, plating, stripping etc. This complex production process occupies large floor space and has also a number of problems such as difficulty in the production of rubber masks and alignment, generation of toxic fumes, high cost of water consumption and sometimes uncertainty on the cleanliness of the surfaces to be plated. A novel laser patterning process is proposed in this paper which can replace many steps in the existing electroplating line. The proposed process involves the application of high speed laser etching techniques on leadframes which were protected with polymer coating. The desired pattern for silver electroplating is produced by laser ablation of the polymer coating. Excimer laser was found to be most effective for this process as it can expose a pattern of clean copper substrate which can be silver plated successfully. Previous working of Nd:YAG laser ablation showed that 1.06 μm radiation was not suitable for this etching process because a thin organic and transparent film remained on the laser etched region. The effect of excimer pulse frequency and energy density upon the removal rate of the polymer coating was studied.

  4. [Results of residual ametropia correction using CIRCLE technology after femtosecond laser SMILE surgery].

    Science.gov (United States)

    Kostin, O A; Rebrikov, S V; Ovchinnikov, A I; Stepanov, A A; Takhchidi, Kh P

    to evaluate functional results of reoperation performed according to the CIRCLE technology and using the VisuMax femtosecond laser and MEL-80 excimer laser in cases of regression of the refractive effect after SMILE surgery. We studied a group of post-SMILE patients. In those, who showed regression of the refractive effect at 1 year, reoperation was performed according to the CIRCLE technology and using the VisuMax femtosecond laser. The corneal flap was separated from the stromal bed and turned aside. Excimer laser ablation of the stromal bed was performed with the MEL 80 machine. The corneal flap was then placed back and rinsed from both sides. Uncorrected (UCVA) and corrected (BCVA) visual acuity as well as spherical equivalent (SE) were estimated before reoperation, on day 1, and at 1 month. After reoperation, BCVA and UCVA improved. Patient refraction became close to emmetropia. Specifically, UCVA was 0.23±0.18 at baseline (i.e. 1 year after SMILE) and 0.93±0.11 after the CIRCLE procedure (pstatistically significant - from 0.95±0.1 to 0.93±0.11 (p>0.05). Reoperation performed according to the CIRCLE technology and using the VisuMax femtosecond laser and MEL-80 excimer laser provides an increase in visual acuity in case of post-SMILE regression of the refractive effect.

  5. Multi-MJ KrF laser driver for a 2050 IFE reactor

    International Nuclear Information System (INIS)

    Linford, G.J.C.

    1992-01-01

    This paper reports on a new design of a multi-megajoule KrF laser driver for the Prometheus inertial fusion energy (IFE) reactor c. year 2050 which has been developed exploiting advances achieved in non-linear optics (NLO) during the past decade. Optimized excimer e-beam sustained electric-discharge lasers (EBSEDLs) are predicted to produce output energies too low (∼4 kJ) with pulses too long (∼500 ns) to meet IFE target irradiation requirements ΔE target ∼ 5 MJ, τ target (∼ 6 ns). The NLO devices used in this design permit the independent optimization of excimer laser modules while providing the important functions of coherent beam combination, intensity smoothing, and temporal pulse compression at high efficiencies

  6. Functional outcomes and patient satisfaction after laser in situ keratomileusis for correction of myopia.

    NARCIS (Netherlands)

    Tahzib, N.G.; Bootsma, S.J.; Eggink, F.A.G.J.; Nabar, V.A.; Nuijts, R.M.

    2005-01-01

    PURPOSE: To determine subjective patient satisfaction and self-perceived quality of vision after laser in situ keratomileusis (LASIK) to correct myopia and myopic astigmatism. SETTING: Department of Ophthalmology, Academic Hospital Maastricht, Maastricht, The Netherlands. METHODS: A validated

  7. Lasers in the automobile industry

    Science.gov (United States)

    Roessler, David M.; Uddin, Nasin

    1996-04-01

    The use of lasers for automotive materials processing is reviewed both from an historical perspective and in terms of current trends. The initial lead gained in North America has subsequently given way to the remarkable growth in the use of lasers in the Japanese automotive industry. The latter's dominance has resulted in cutting being the most common laser machining application on a global basis, even though welding predominates in the US. About 98% of all automotive laser materials processing employs either CO2 or Nd:YAG lasers, although there are special applications where the excimer or other lasers can be found. This paper discusses two of the processes currently receiving most attention. Laser technology is not stagnant and the automotive industry continues to benefit from the continuing developments. However, even more striking growth can be expected as the whole process of automotive manufacture is being re-examined in response to the demands for more fuel- efficient and environmentally friendly, but still affordable and satisfying, vehicles.

  8. 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

  9. Analysis on second operation after laser in situ keratomileusis

    Directory of Open Access Journals (Sweden)

    Wen-Xuan Pei

    2015-07-01

    Full Text Available AIM: To observe clinical effects between the laser in situ keratomileusis(LASIKsurgery and the laser subepithelial keratomileusis(LASEKsurgery as the second operation after an unsuccessful LASIK surgery. METHODS:Forty-nine patients(98 eyeswith refractive regression after LASIK operation received the second surgery. All patients were divided into two groups: group A and B. Group A(48 eyes of 24 patientsreceived LASIK surgery and group B(50 eyes of 25 patientsreceived LASEK surgery. Inspect the main parameters included visual acuity, refraction, corneal curvature, and the total value of high-aberration after 1wk, 1mo and 1a, t-test of groups was used as statistical analysis method.RESULTS: There was statistically significant(PP>0.05. There developed one case of epithelium in growth after LASIK surgery, and one case of haze Ⅱ after LASEK surgery. CONCLUSION: Both LASIK and LASEK surgery can obtain satisfactory therapeutic results after an unsuccessful LASIK surgery.

  10. Wavefront-guided versus standard laser in situ keratomileusis to correct low to moderate myopia.

    NARCIS (Netherlands)

    Nuijts, R.M.; Nabar, V.A.; Hament, W.J.; Eggink, F.A.G.J.

    2002-01-01

    To evaluate the 6-month refractive outcomes of wavefront-guided laser in situ keratomileusis (LASIK) (Zyoptix, Bausch & Lomb) versus standard LASIK (PlanoScan, Bausch & Lomb).Department of Ophthalmology, University Hospital Maastricht, Maastricht, The Netherlands.In a prospective randomized study,

  11. 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.

  12. 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.

  13. Investigation and in situ removal of spatter generated during laser ablation of aluminium composites

    International Nuclear Information System (INIS)

    Popescu, A.C.; Delval, C.; Shadman, S.; Leparoux, M.

    2016-01-01

    Highlights: • Study of spatter generated during laser irradiation of an aluminium nanocomposite. • Number of droplets was 1.5–3 times higher for laser in depth vs surface focused beams. • High speed imaging revealed particles exploding in flight similar to a fireworks effect. • Three methods were selected for droplets removal in situ and the results are analyzed. - Abstract: Spatter generated during laser irradiation of an aluminium alloy nanocomposite (AlMg5 reinforced with Al_2O_3 nanoparticles) was monitored by high speed imaging. Droplets trajectory and speed were assessed by computerized image analysis. The effects of laser peak power and laser focusing on the plume expansion and expulsed droplet speeds were studied in air or under argon flow. It was found that the velocity of visible droplets expulsed laterally or at the end of the plume emission from the metal surface was not dependent on the plasma plume speed. The neighbouring area of irradiation sites was studied by optical and scanning electron microscopy. Droplets deposited on the surface were classified according to their size and counted using a digital image processing software. It was observed that the number of droplets on surface was 1.5–3 times higher when the laser beam was focused in depth as compared to focused beams, even though the populations average diameter were comparable. Three methods were selected for removing droplets in situ, during plume expansion: an argon gas jet crossing the plasma plume, a fused silica plate collector transparent to the laser wavelength placed parallel to the irradiated surface and a mask placed onto the aluminium composite surface. The argon gas jet was efficient only for low power irradiation conditions, the fused silica plate failed in all tested conditions and the mask was successful for all irradiation regimes.

  14. In-situ CdS/CdTe Heterojuntions Deposited by Pulsed Laser Deposition

    KAUST Repository

    Avila-Avendano, Jesus

    2016-04-09

    In this paper pulsed laser deposition (PLD) methods are used to study p-n CdTe/CdS heterojunctions fabricated in-situ. In-situ film deposition allows higher quality p-n interfaces by minimizing spurious contamination from the atmosphere. Morphologic and structural analyses were carried for CdTe films deposited on various substrates and different deposition conditions. The electrical characteristics and performance of the resulting p-n heterojunctions were studied as function of substrate and post-deposition anneal temperature. In-situ growth results on diodes with a rectification factor of ~ 105, an ideality factor < 2, and a reverse saturation current ~ 10-8 A. The carrier concentration in the CdTe film was in the range of ~ 1015 cm-3, as measured by C-V methods. The possible impact of sulfur diffusion from the CdS into the CdTe film is also investigated using High Resolution Rutherford Back-Scattering.

  15. In-situ CdS/CdTe Heterojuntions Deposited by Pulsed Laser Deposition

    KAUST Repository

    Avila-Avendano, Jesus; Mejia, Israel; Alshareef, Husam N.; Guo, Zaibing; Young, Chadwin; Quevedo-Lopez, Manuel

    2016-01-01

    In this paper pulsed laser deposition (PLD) methods are used to study p-n CdTe/CdS heterojunctions fabricated in-situ. In-situ film deposition allows higher quality p-n interfaces by minimizing spurious contamination from the atmosphere. Morphologic and structural analyses were carried for CdTe films deposited on various substrates and different deposition conditions. The electrical characteristics and performance of the resulting p-n heterojunctions were studied as function of substrate and post-deposition anneal temperature. In-situ growth results on diodes with a rectification factor of ~ 105, an ideality factor < 2, and a reverse saturation current ~ 10-8 A. The carrier concentration in the CdTe film was in the range of ~ 1015 cm-3, as measured by C-V methods. The possible impact of sulfur diffusion from the CdS into the CdTe film is also investigated using High Resolution Rutherford Back-Scattering.

  16. In situ ozone data for comparison with laser absorption remote sensor: 1980 pepe/neros program

    International Nuclear Information System (INIS)

    Mcdougal, D.S.; Lee, R.B. III; Bendura, R.J.

    1982-05-01

    Several sets of in situ ozone (O 3 ) measurements were made by a NASA aircraft in support of the laser absorption spectrometer (LAS) remote sensor. These measurements were designed to provide comparative O 3 data for the LAS sensor. The LAS, which was flown on a second aircraft, remotely measured the vertical burden of O 3 from the aircraft to the surface. In situ results of the air quality (O 3 and B sub scat) and meteorological (temperature and dewpoint) parameters for three correlative missions are presented. The aircraft flight plans, in situ concentration profiles and vertical burdens, and measurement errors are summarized

  17. Recent advances in laser in situ keratomileusis-associated dry eye.

    Science.gov (United States)

    Xie, Wenjia

    2016-03-01

    Dry eye is the most common complication after laser in situ keratomileusis (LASIK). The major cause of LASIK-associated dry eye is corneal nerve damage. Early identification and treatment of post-operative dry eye are essential to prevent further ocular surface damage. This article reviews the recent studies of LASIK-associated dry eye, including clinical features, aetiology, risk factors, evaluations and treatment. The applications of novel technologies in LASIK-associated dry eye evaluation like anterior segment spectral-domain optical coherence tomography (SD-OCT) and corneal confocal microscopy are also introduced in this review. © 2016 Optometry Australia.

  18. The growth of large-area superconducting YBa2Cu3O7-x thin films by pulsed laser ablation

    International Nuclear Information System (INIS)

    Lai, H.C.; Chang, C.M.; Lin, R.J.; Liu, R.S.

    1996-01-01

    In-situ growth of 2-in. diameter superconducting YBa 2 Cu 3 O 7-x (YBCO) thin films using an excimer KrF pulsed laser has been studied. Films with critical transition temperature (T c,0 ) of 89±1 K and critical current density (J c,77K ) in excess of 1 x 10 6 A cm -2 have been prepared routinely. Uniformity in film thickness of below ±15% and film composition of ±5% have been measured. The effects of gas nozzle geometry and target evolution during ablation on the superconducting properties and surface morphology of YBCO thin films have also been investigated. (orig.)

  19. In situ laser heating and radial synchrotron X-ray diffraction ina diamond anvil cell

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, Martin; Caldwell, Wendel A.; Miyagi, Lowell; Wenk,Hans-Rudolf

    2007-06-29

    We report a first combination of diamond anvil cell radialx-ray diffraction with in situ laser heating. The laser-heating setup ofALS beamline 12.2.2 was modified to allow one-sided heating of a samplein a diamond anvil cell with an 80 W yttrium lithium fluoride laser whileprobing the sample with radial x-ray diffraction. The diamond anvil cellis placed with its compressional axis vertical, and perpendicular to thebeam. The laser beam is focused onto the sample from the top while thesample is probed with hard x-rays through an x-ray transparentboron-epoxy gasket. The temperature response of preferred orientation of(Fe,Mg)O is probed as a test experiment. Recrystallization was observedabove 1500 K, accompanied by a decrease in stress.

  20. Intramolecular excimer and exciplex emission of 1,4-dipyrenyl substituted cyclohexasilane

    NARCIS (Netherlands)

    van Walree, C.A.; Kaats-Richters, V.E.M.; Jenneskens, L.W.; Williams, R.M.; van Stokkum, I.H.M.

    2002-01-01

    Intramolecular excimer emission is observed for cis-1,4-di(1-pyrenyl)decamethylcyclohexasilane in nonpolar solvents. Time-resolved fluorescence spectroscopy and kinetic modelling indicate that the driving force of excimer formation is very small, and that the process is governed by the flexibility

  1. 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.

  2. 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.

  3. Tunable lasers for waste management photochemistry applications

    International Nuclear Information System (INIS)

    Finch, F.T.

    1978-09-01

    A review of lasers with potential photochemical applications in waste management indicates that dye lasers, as a class, can provide tunable laser output through the visible and near-uv regions of the spectrum of most interest to photochemistry. Many variables can affect the performance of a specific dye laser, and the interactions of these variables, at the current state of the art, are complex. The recent literature on dye-laser characteristics has been reviewed and summarized, with emphasis on those parameters that most likely will affect the scaling of dye lasers in photochemical applications. Current costs are reviewed and correlated with output power. A new class of efficient uv lasers that appear to be scalable in both energy output and pulse rate, based on rare-gas halide excimers and similar molecules, is certain to find major applications in photochemistry. Because the most important developments are too recent to be adequately described in the literature or are the likely outcome of current experiments, the basic physics underlying the class of excimer lasers is described. Specific cost data are unavailable, but these new gas lasers should reflect costs similar to those of existing gas lasers, in particular, the pulsed CO 2 lasers. To complete the survey of tunable-laser characteristics, the technical characteristics of the various classes of lasers in the ir are summarized. Important developments in ir laser technology are being accelerated by isotope-separation research, but, initially at least, this portion of the spectrum is least likely to receive emphasis in waste-management-oriented photochemistry

  4. Lasers in endodontics: an overview

    Science.gov (United States)

    Frentzen, Matthias; Braun, Andreas; Koort, Hans J.

    2002-06-01

    The interest in endodontic use of dental laser systems is increasing. Developing laser technology and a better understanding of laser effects widened the spectrum of possible endodontic indications. Various laser systems including excimer-, argon+-, diode-, Nd:YAG-, Er:YAG- and CO2-lasers are used in pulp diagnosis, treatment of hypersensitivity, pulp capping, sterilization of root canals, root canal shaping and obturation or apicoectomy. With the development of new delivery systems - thin and flexible fibers - for many different wavelengths laser applications in endodontics may increase. Since laser devices are still relatively costly, access to them is limited. Most of the clinical applications are laser assisted procedures such as the removing of pulp remnants and debris or disinfection of infected root canals. The essential question is whether a laser can provide improved treatment over conventional care. To perform laser therapy in endodontics today different laser types with adopted wavelengths and pulse widths are needed, each specific to a particular application. Looking into the future we will need endodontic laser equipment providing optimal laser parameters for different treatment modalities. Nevertheless, the quantity of research reports from the last decade promises a genuine future for lasers in endodontics.

  5. Bilateral Simultaneous Rhegmatogenous Retinal Detachment following Laser in situ Keratomileusis

    Directory of Open Access Journals (Sweden)

    Erhan Yumusak

    2016-06-01

    Full Text Available A 21-year-old woman developed simultaneous rhegmatogenous retinal detachment after laser in situ keratomileusis (LASIK in both eyes. She underwent pars plana vitrectomy surgery combined with endolaser photocoagulation and silicone oil tamponade in the right eye. A week later, pneumatic retinopexy was done in the left eye. As the retinal tear did not seal, 360° scleral buckling surgery was performed and retina was attached. Bilateral simultaneous rhegmatogenous retinal detachment after LASIK for correction of myopia can be a serious complication. Patients should be informed about the possibility of this complication.

  6. Influence of laser surface modifying of polyethylene terephthalate on fibroblast cell adhesion

    International Nuclear Information System (INIS)

    Mirzadeh, H.; Dadsetan, M.

    2003-01-01

    Attempts have been made to evaluate the changes in physical and chemical properties of the polyethylene terephthalate (PET) surface due to laser irradiation. These changes have been investigated from viewpoints of microstructuring and its effect on fibroblast cell behavior. The surfaces of PET were irradiated using CO 2 and KrF excimer pulsed laser. The changes were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM) and contact angle measurements. The data from ATR-FTIR spectra showed that the crystallinity in the surface region decreased due to the CO 2 and excimer laser irradiation. SEM observations showed that specific microstructures were created on the PET surface due to laser irradiation. In order to study biocompatibility and cell behavior, we utilized standard in vitro L929-fibroblast cell culture system. Fibroblast cell adhesion and spreading were significantly correlated to the morphology and wettability of the laser irradiated PET surface

  7. 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.

  8. PRK by Er:YAG laser: in-vitro studies and first in-vivo experiences

    Science.gov (United States)

    Steiner, Rudolf W.; Leiacker, Richard; Russ, Detlef; Seiler, Theo

    1996-01-01

    Photorefractive keratectomy (PRK) is usually performed by an excimer laser at 193 nm wavelength. Ablatio of corneal tissue is, however, not only possible in the UV region of the optical spectrum but also in the IR where water is an excellent absorber. Therefore, an Er:YAG laser was used at 2.94 micrometer wavelength as an alternative laser light source to perform in vitro studies of corneal ablation and also first clinical experiments to correct myopia of patients with blind eyes.

  9. Annual report to the Laser Facility Committee 1984

    International Nuclear Information System (INIS)

    1984-01-01

    The report describes the work carried out at, or in association with, the Central Laser Facility (CLF), during the year ending March 1984. The CLF programme is divided into three main sections. The first, the glass laser scientific programme, is concerned with applications of the high power Nd glass laser. The second, the ultra violet radiation facility scientific programme, involves the excimer pumped frequency tunable lasers. The last, high power KrF laser development, describes Research and development work on this laser. (U.K.)

  10. Laser precision microfabrication in Japan

    Science.gov (United States)

    Miyamoto, Isamu; Ooie, Toshihiko; Takeno, Shozui

    2000-11-01

    Electronic devices such as handy phones and micro computers have been rapidly expanding their market recent years due to their enhanced performance, down sizing and cost down. This has been realized by the innovation in the precision micro- fabrication technology of semiconductors and printed wiring circuit boards (PWB) where laser technologies such as lithography, drilling, trimming, welding and soldering play an important role. In phot lithography, for instance, KrF excimer lasers having a resolution of 0.18 micrometers has been used in production instead of mercury lamp. Laser drilling of PWB has been increased up to over 1000 holes per second, and approximately 800 laser drilling systems of PWB are expected to be delivered in the world market this year, and most of these laser processing systems are manufactured in Japan. Trend of laser micro-fabrication in Japanese industry is described along with recent topics of R&D, government supported project and future tasks of industrial laser precision micro-fabrication on the basis of the survey conducted by Japan laser Processing Society.

  11. 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.

  12. Methodology for in situ synchrotron X-ray studies in the laser-heated diamond anvil cell

    DEFF Research Database (Denmark)

    Mezouar, M.; Giampaoli, R.; Garbarino, G.

    2017-01-01

    A review of some important technical challenges related to in situ diamond anvil cell laser heating experimentation at synchrotron X-ray sources is presented. The problem of potential chemical reactions between the sample and the pressure medium or the carbon from the diamond anvils is illustrated...

  13. 3D reconstruction and characterization of laser induced craters by in situ optical microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Casal, A.; Cerrato, R.; Mateo, M.P.; Nicolas, G., E-mail: gines@udc.es

    2016-06-30

    Highlights: • Evolution of the laser induced crater and ablation features by in situ homemade optical microscope. • Performance comparison between confocal microscope for material characterization and homemade optical microscope. • Coupled system of laser ablation setup with a low cost optical microscope. - Abstract: A low-cost optical microscope was developed and coupled to an irradiation system in order to study the induced effects on material during a multipulse regime by an in situ visual inspection of the surface, in particular of the spot generated at different pulses. In the case of laser ablation, a reconstruction of the crater in 3D was made from the images of the sample surface taken during the irradiation process, and the subsequent profiles of ablated material were extracted. The implementation of this homemade optical device gives an added value to the irradiation system, providing information about morphology evolution of irradiated area when successive pulses are applied. In particular, the determination of ablation rates in real time can be especially useful for a better understanding and controlling of the ablation process in applications where removal of material is involved, such as laser cleaning and in-depth characterization of multilayered samples and diffusion processes. The validation of the developed microscope was made by a comparison with a commercial confocal microscope configured for the characterization of materials where similar results of crater depth and diameter were obtained for both systems.

  14. 3D reconstruction and characterization of laser induced craters by in situ optical microscopy

    International Nuclear Information System (INIS)

    Casal, A.; Cerrato, R.; Mateo, M.P.; Nicolas, G.

    2016-01-01

    Highlights: • Evolution of the laser induced crater and ablation features by in situ homemade optical microscope. • Performance comparison between confocal microscope for material characterization and homemade optical microscope. • Coupled system of laser ablation setup with a low cost optical microscope. - Abstract: A low-cost optical microscope was developed and coupled to an irradiation system in order to study the induced effects on material during a multipulse regime by an in situ visual inspection of the surface, in particular of the spot generated at different pulses. In the case of laser ablation, a reconstruction of the crater in 3D was made from the images of the sample surface taken during the irradiation process, and the subsequent profiles of ablated material were extracted. The implementation of this homemade optical device gives an added value to the irradiation system, providing information about morphology evolution of irradiated area when successive pulses are applied. In particular, the determination of ablation rates in real time can be especially useful for a better understanding and controlling of the ablation process in applications where removal of material is involved, such as laser cleaning and in-depth characterization of multilayered samples and diffusion processes. The validation of the developed microscope was made by a comparison with a commercial confocal microscope configured for the characterization of materials where similar results of crater depth and diameter were obtained for both systems.

  15. 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

  16. UV laser engraving of high temperature polymeric materials

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  17. 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.

  18. Ultraviolet-laser ablation of skin

    Energy Technology Data Exchange (ETDEWEB)

    Lane, R.J.; Linsker, R.; Wynne, J.J.; Torres, A.; Geronemus, R.G.

    1985-05-01

    The authors report on the use of pulsed ultraviolet-laser irradiation at 193 nm from an argon-fluoride laser and at 248 nm from a krypton-fluoride laser to ablate skin. In vitro, both wavelengths performed comparably, removing tissue precisely and cleanly, and leaving minimal thermal damage to the surrounding tissue. In vivo, the 193-nm laser radiation failed to remove tissue after bleeding began. The 248-nm radiation, however, continued to remove tissue despite bleeding and left a clean incision with only minimal thermal damage. The krypton-fluoride excimer laser beam at 248 nm, which should be deliverable through a quartz optical fiber, has great potential as a surgical instrument.

  19. 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

  20. In situ investigation of the tensile deformation of laser welded Ti{sub 2}AlNb joints

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kezhao; Ni, Longchang; Lei, Zhenglong, E-mail: leizhenglong@hit.edu.cn; Chen, Yanbin; Hu, Xue

    2017-01-15

    The tensile deformation behavior of laser welded Ti{sub 2}AlNb joints was investigated using in situ analysis methods. The fracture mode of the single-B2-phase fusion zone was quasi-cleavage at room temperature and intergranular at 650 °C, while that of base metal was microvoid coalescence at both room temperature and 650 °C. Tensile deformation at room temperature was observed using in situ SEM tensile testing. In base metal, microcracks nucleated and propagated mainly within the O phase or along O/B2 phase boundaries. While both the cross- and multi-slips were found in the single-B2-phase fusion zone, a confocal laser scanning microscopy was used to observe the crack initiation and propagation process in situ at 650 °C. Cracks mainly formed along the B2/O phase boundaries in base metal, along the fragile grain boundaries of B2 phase in the fusion zone. The thermal simulation experiment and following TEM analysis indicated that the precipitation of continuous O-phase films along the B2 grain boundaries resulted in the high temperature brittleness of laser welded Ti{sub 2}AlNb joints. - Highlights: •Cracks formed within O phase or along B2/O boundaries in the base metal. •Cross- and multi-slips relieved stress in the fusion zone at room temperature. •Cracks mainly formed along the B2/O boundaries at 650 °C. •In the fusion zone, intergranular cracks were in situ observed at 650 °C. •O-phase films along B2 grain boundaries caused the high temperature brittleness.

  1. 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

  2. Complications of laser in situ keratomileusis (LASIK) for correction of myopia and their management

    Energy Technology Data Exchange (ETDEWEB)

    Lotfy, A A

    2002-07-01

    Complication of Laser in situ keratomileusis (Lasik) For correction of myopia and their management. Lasik has many many complications that the study discussed and also their management. Complications include; bleeding, infection, corneal haze and scarring, lost or displaced flap, corneal complications, over and under correction, and regression of refraction.

  3. Complications of laser in situ keratomileusis (LASIK) for correction of myopia and their management

    International Nuclear Information System (INIS)

    Lotfy, A. A.

    2002-01-01

    Complication of Laser in situ keratomileusis (Lasik) For correction of myopia and their management. Lasik has many many complications that the study discussed and also their management. Complications include; bleeding, infection, corneal haze and scarring, lost or displaced flap, corneal complications, over and under correction, and regression of refraction

  4. Plastic scintillators based on polymers with eliminated excimer forming

    Energy Technology Data Exchange (ETDEWEB)

    Adadurov, A.F., E-mail: adadurov@isma.kharkov.u [Institute for Scintillating Materials NAN of Ukraine, 60 Lenin Ave, 61001 Kharkov (Ukraine); Yelyseev, D.A.; Titskaya, V.D.; Lebedev, V.N.; Zhmurin, P.N. [Institute for Scintillating Materials NAN of Ukraine, 60 Lenin Ave, 61001 Kharkov (Ukraine)

    2011-05-15

    Plastic scintillators (PS) were made based on benzyl methacrylate and methyl-methacrylate P(BzMA + MMA) copolymer in which the excimer forming rate is by two order lesser than that in polystyrene-based polymer matrix. Studying of these PS light yield demonstrates the importance of migration processes comparing to excimer formation. It is found that to obtain PS with high scintillation efficiency it is necessary to use the polymer base (matrix) in which excimer forming is eliminated but the migration process along the chromophores is maximally favored. To explain the accelerated energy transfer between phenyl chromophores it is proposed to use a mechanism of exchange of that virtual excitons that can propagate along a one-dimensional back-bone of polymer molecule. Clearing the details of mechanism of interaction between chromophores of polymer molecules which is responsible for accelerated radiationless energy transfer enable will determine in future the way of effective plastic scintillators designing.

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

    Science.gov (United States)

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

    2003-03-01

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

  6. Corneal biomechanical properties after laser-assisted in situ keratomileusis and photorefractive keratectomy

    Directory of Open Access Journals (Sweden)

    Hwang ES

    2017-10-01

    Full Text Available Eileen S Hwang,1 Brian C Stagg,1 Russell Swan,1 Carlton R Fenzl,1 Molly McFadden,2 Valliammai Muthappan,1 Luis Santiago-Caban,1 Mark D Mifflin,1 Majid Moshirfar1,3 1Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, 2Department of Internal Medicine, University of Utah, Salt Lake City, 3HDR Research Center, Hoopes Vision, Draper, UT, USA Background: The purpose of this study was to evaluate the effects of laser-assisted in situ keratomileusis (LASIK and photorefractive keratectomy (PRK on corneal biomechanical properties.Methods: We used the ocular response analyzer to measure corneal hysteresis (CH and corneal resistance factor (CRF before and after refractive surgery.Results: In all, 230 eyes underwent LASIK and 115 eyes underwent PRK without mitomycin C (MMC. Both procedures decreased CH and CRF from baseline. When MMC was used after PRK in 20 eyes, it resulted in lower corneal biomechanical properties at 3 months when compared to the other procedures, but all three procedures had similar values at 12 months.Conclusion: Significant but similar decreases in corneal biomechanical properties after LASIK, PRK without MMC, and PRK with MMC were noted. Keywords: corneal biomechanics, photorefractive keratectomy, laser-assisted in situ keratomileusis, corneal hysteresis, corneal resistance factor, mitomycin C

  7. Generation of various carbon nanostructures in water using IR/UV laser ablation

    International Nuclear Information System (INIS)

    Mortazavi, Seyedeh Zahra; Parvin, Parviz; Reyhani, Ali; Mirershadi, Soghra; Sadighi-Bonabi, Rasoul

    2013-01-01

    A wide variety of carbon nanostructures were generated by a Q-switched Nd : YAG laser (1064 nm) while mostly nanodiamonds were created by an ArF excimer laser (193 nm) in deionized water. They were characterized by transmission electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy. It was found that the IR laser affected the morphology and structure of the nanostructures due to the higher inverse bremsstrahlung absorption rate within the plasma plume with respect to the UV laser. Moreover, laser-induced breakdown spectroscopy was carried out so that the plasma created by the IR laser was more energetic than that generated by the UV laser. (paper)

  8. Progress in high-energy laser technology

    International Nuclear Information System (INIS)

    Miyanaga, Noriaki; Kitagawa, Yoneyoshi; Nakatsuka, Masahiro; Kanabe, Tadashi; Okuda, Isao

    2005-01-01

    The technological development of high-energy lasers is one of the key issues in laser fusion research. This paper reviews several technologies on the Nd:glass laser and KrF excimer laser that are being used in the current laser fusion experiments and related plasma experiments. Based on the GEKKO laser technology, a new high-energy Nd: glass laser system, which can deliver energy from 10 kJ (boad-band operation) to 20 kJ (narrow-band operation), is under construction. The key topics in KrF laser development are improved efficiency and repetitive operation, which aim at the development of a laser driven for fusion reactor. Ultra-intense-laser technology is also very important for fast ignition research. The key technology for obtaining the petawatt output with high beam quality is reviewed. Regarding the uniform laser irradiation required for high-density compression, the beam-smoothing methods on the GEKKO XII laser are reviewed. Finally, we discuss the present status of MJ-class lasers throughout the world, and summarize by presenting the feasibility of various applications of the high-energy lasers to a wide range of scientific and technological fields. (author)

  9. Risk Factors for Retreatment Following Myopic LASIK with Femtosecond Laser and Custom Ablation for the Treatment of Myopia.

    Science.gov (United States)

    Kruh, Jonathan N; Garrett, Kenneth A; Huntington, Brian; Robinson, Steve; Melki, Samir A

    2017-01-01

    To identify risks factors for retreatment post-laser in situ keratomeliusis (LASIK). A retrospective chart review from December 2008 to September 2012 identified 1,402 patients (2,581 eyes) that underwent LASIK treatment for myopia with the Intralase™ FS, STAR S4 IR™ Excimer Laser, and WaveScan WaveFront™ technology. In this group, 83 patients were retreated. All charts were reviewed for preoperative age, gender, initial manifest refraction spherical equivalent (MRSE), total astigmatism, and iris registration. Increased incidence rates of retreatment post-LASIK were preoperative age >40 years (p -3.0 D (p = 0.02), and astigmatism >1D (p = 0.001). Iris registration capture did not significantly reduce the retreatment rate (p = 0.12). Risk factors for retreatment included preoperative age >40 years, initial MRSE > -3.0 D, and astigmatism >1D. There was no difference in retreatment rate for patients based on gender or iris registration capture.

  10. Remote in-situ laser-induced breakdown spectroscopy using optical fibers

    Science.gov (United States)

    Marquardt, Brian James

    The following dissertation describes the development of methods for performing remote Laser-Induced Breakdown Spectroscopy (LIBS) using optical fibers. Studies were performed to determine the optimal excitation and collection parameters for remote LIBS measurements of glasses, soils and paint. A number of fiber-optic LIBS probes were developed and used to characterize various samples by plasma emission spectroscopy. A novel method for launching high-power laser pulses into optical fibers without causing catastrophic failure is introduced. A systematic study of a number of commercially available optical fibers was performed to determine which optical fibers were best suited for delivering high-power laser pulses. The general design of an all fiber-optic LIBS probe is described and applied to the determination of Pb in soil. A fiber-optic probe was developed for the microanalysis of solid samples remotely by LIBS, Raman spectroscopy and Raman imaging. The design of the probe allows for real-time sample imaging in-situ using coherent imaging fibers. This allows for precise atomic emission and Raman measurements to be performed remotely on samples in hostile or inaccessible environments. A novel technique was developed for collecting spectral plasma images using an acousto-optic tunable filter (AOTF). The spatial and temporal characteristics of the plasma were studied as a function of delay time. From the plasma images the distribution of Pb emission could be determined and fiber-optic designs could be optimized for signal collection. The performance of a two fiber LIBS probe is demonstrated for the determination of the amount of lead in samples of dry paint. It is shown that dry paint samples can be analyzed for their Pb content in-situ using a fiber-optic LIBS probe with detection limits well below the levels currently regulated by the Consumer Products Safety Commission. It is also shown that these measurements can be performed on both latex and enamel paints, and

  11. Pulsed laser deposition and characterization of multilayer metal-carbon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Siraj, K., E-mail: khurram.uet@gmail.com [Advance Physics Laboratory, Department of Physics, University of Engineering and Technology, Lahore (Pakistan); Khaleeq-ur-Rahman, M.; Rafique, M.S.; Munawar, M.Z. [Advance Physics Laboratory, Department of Physics, University of Engineering and Technology, Lahore (Pakistan); Naseem, S.; Riaz, S. [Center for Solid State Physics, University of Punjab, Lahore (Pakistan)

    2011-05-15

    Cobalt-DLC multilayer films were deposited with increasing content of cobalt, keeping carbon content constant by pulsed laser deposition technique. A cobalt free carbon film was also deposited for comparison. Excimer laser was employed to ablate the materials onto silicon substrate, kept at 250 deg. C, while post-deposition annealing at 400 deg. C was also performed in situ. The formation of cobalt grains within the carbon matrix in Co-DLC films can be seen through scanning electron and atomic force micrographs while no grains on the surface of the cobalt-free DLC film were observed. Raman spectra of all the films show D- and G-bands, which is a confirmation that the films are DLC in nature. According to Vibrating sample magnetometer (VSM) measurements, the DLC films with cobalt revealed ferromagnetic behaviour whereas the cobalt free DLC film exhibited diamagnetic behaviour. The pure DLC film also shows ferromagnetic nature when diamagnetic background is subtracted. Spectroscopic Ellipsometry (SE) analysis showed that the optical band gaps, refractive indices and extinction coefficients of Co-DLC films can be effectively tuned with increasing content of cobalt.

  12. Pulsed laser deposition and characterization of multilayer metal-carbon thin films

    International Nuclear Information System (INIS)

    Siraj, K.; Khaleeq-ur-Rahman, M.; Rafique, M.S.; Munawar, M.Z.; Naseem, S.; Riaz, S.

    2011-01-01

    Cobalt-DLC multilayer films were deposited with increasing content of cobalt, keeping carbon content constant by pulsed laser deposition technique. A cobalt free carbon film was also deposited for comparison. Excimer laser was employed to ablate the materials onto silicon substrate, kept at 250 deg. C, while post-deposition annealing at 400 deg. C was also performed in situ. The formation of cobalt grains within the carbon matrix in Co-DLC films can be seen through scanning electron and atomic force micrographs while no grains on the surface of the cobalt-free DLC film were observed. Raman spectra of all the films show D- and G-bands, which is a confirmation that the films are DLC in nature. According to Vibrating sample magnetometer (VSM) measurements, the DLC films with cobalt revealed ferromagnetic behaviour whereas the cobalt free DLC film exhibited diamagnetic behaviour. The pure DLC film also shows ferromagnetic nature when diamagnetic background is subtracted. Spectroscopic Ellipsometry (SE) analysis showed that the optical band gaps, refractive indices and extinction coefficients of Co-DLC films can be effectively tuned with increasing content of cobalt.

  13. Effect of laser in situ keratomileusis with corneal flap created by femtosecond laser on tear film detected by Keratograph in different age groups

    Directory of Open Access Journals (Sweden)

    Yu-Xia Zhang

    2016-03-01

    Full Text Available AIM:To explore the changes of tear film detected by Keratograph in the patients after laser in situ keratomileusis(LASIKwith corneal flap created by femtosecond laser. METHODS: Totally 75 myopic patients(150 eyeswere enrolled who underwent femtosecond laser LASIK from July 2014 to June 2015, including patientsRESULTS: Before surgeries, the dry eye symptoms score of three groups had no significant difference(P>0.05. After surgeries, there were significant difference at each follow-up time among the three groups on symptoms score(PPCONCLUSION: LASIK can affect the dry eye symptoms and the stability of tear film, which decreased by postoperative time. And the index recovered to preoperative levels earlier in younger patients.

  14. Study of laser plasma emission from doped targets

    Czech Academy of Sciences Publication Activity Database

    Velardi, L.; Krása, Josef; Velyhan, Andriy; Nassisi, V.

    2012-01-01

    Roč. 83, č. 2 (2012), , "02B911-1"-"02B911-3" ISSN 0034-6748 R&D Projects: GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528 EU Projects: European Commission(XE) 228334 - LASERLAB-EUROPE Institutional research plan: CEZ:AV0Z10100523 Keywords : copper * excimer lasers * ion mobility * krypton compounds * laser ablation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.602, year: 2012

  15. 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...

  16. Preliminary results of in situ laser-induced breakdown spectroscopy for the first wall diagnostics on EAST

    Science.gov (United States)

    Hu, Zhenhua; Li, Cong; Xiao, Qingmei; Liu, Ping; Fang, Ding; Mao, Hongmin; Wu, Jing; Zhao, Dongye; Ding, Hongbin; Luo, Guang-Nan; EAST Team

    2017-02-01

    Post-mortem methods cannot fulfill the requirement of monitoring the lifetime of the plasma facing components (PFC) and measuring the tritium inventory for the safety evaluation. Laser-induced breakdown spectroscopy (LIBS) is proposed as a promising method for the in situ study of fuel retention and impurity deposition in a tokamak. In this study, an in situ LIBS system was successfully established on EAST to investigate fuel retention and impurity deposition on the first wall without the need of removal tiles between plasma discharges. Spectral lines of D, H and impurities (Mo, Li, Si, … ) in laser-induced plasma were observed and identified within the wavelength range of 500-700 nm. Qualitative measurements such as thickness of the deposition layers, element depth profile and fuel retention on the wall are obtained by means of in situ LIBS. The results demonstrated the potential applications of LIBS for in situ characterization of fuel retention and co-deposition on the first wall of EAST. Supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB105002, 2015GB109001, and 2013GB109005), National Natural Science Foundation of China (Nos. 11575243, 11605238, 11605023), Chinesisch-Deutsches Forschungs Project (GZ765), and Korea Research Council of Fundamental Science and Technology (KRCF) under the international collaboration & research in Asian countries (PG1314).

  17. Laser Thomson scattering diagnostics of non-equilibrium high pressure plasmas

    International Nuclear Information System (INIS)

    Muraoka, K.; Uchino, K.; Bowden, M.D.; Noguchi, Y.

    2001-01-01

    For various applications of non-equilibrium high pressure plasmas, knowledge of electron properties, such as electron density, electron temperature and/or electron energy distribution function (eedf), is prerequisite for any rational approach to understanding physical and chemical processes occurring in the plasmas. For this purpose, laser Thomson scattering has been successfully applied for the first time to measure the electron properties in plasmas for excimer laser pumping and in microdischarges. Although this diagnostic technique is well established for measurements in high temperature plasmas, its applications to these glow discharge plasmas have had various inherent difficulties, such as a presence of high density neutral particles (>10 21 m -3 ) in the excimer laser pumping discharges and an extremely small plasma size (<0.1 mm) and the presence of nearby walls for microdischarges. These difficulties have been overcome and clear signals have been obtained. The measured results are presented and their implications in the respective discharge phenomena are discussed

  18. Investigation into the Use of the Concept Laser QM System as an In-Situ Research and Evaluation Tool

    Science.gov (United States)

    Bagg, Stacey

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) is using a Concept Laser Fusing (Cusing) M2 powder bed additive manufacturing system for the build of space flight prototypes and hardware. NASA MSFC is collecting and analyzing data from the M2 QM Meltpool and QM Coating systems for builds. This data is intended to aide in understanding of the powder-bed additive manufacturing process, and in the development of a thermal model for the process. The QM systems are marketed by Concept Laser GmbH as in-situ quality management modules. The QM Meltpool system uses both a high-speed near-IR camera and a photodiode to monitor the melt pool generated by the laser. The software determines from the camera images the size of the melt pool. The camera also measures the integrated intensity of the IR radiation, and the photodiode gives an intensity value based on the brightness of the melt pool. The QM coating system uses a high resolution optical camera to image the surface after each layer has been formed. The objective of this investigation was to determine the adequacy of the QM Meltpool system as a research instrument for in-situ measurement of melt pool size and temperature and its applicability to NASA's objectives in (1) Developing a process thermal model and (2) Quantifying feedback measurements with the intent of meeting quality requirements or specifications. Note that Concept Laser markets the system only as capable of giving an indication of changes between builds, not as an in-situ research and evaluation tool. A secondary objective of the investigation is to determine the adequacy of the QM Coating system as an in-situ layer-wise geometry and layer quality evaluation tool.

  19. In situ measurements of fuel retention by laser induced desorption spectroscopy in TEXTOR

    Science.gov (United States)

    Zlobinski, M.; Philipps, V.; Schweer, B.; Huber, A.; Stoschus, H.; Brezinsek, S.; Samm, U.; TEXTOR Team

    2011-12-01

    In future fusion devices such as ITER tritium retention due to tritium co-deposition in mixed material layers can be a serious safety problem. Laser induced desorption spectroscopy (LIDS) can measure the hydrogen content of hydrogenic carbon layers locally on plasma-facing components, while hydrogen is used as a tritium substitute. For several years, this method has been applied in the TEXTOR tokamak in situ during plasma operation to monitor the hydrogen content in space and time. This work shows the LIDS signal reproducibility and studies the effects of different plasma conditions, desorption distances from the plasma and different laser energies using a dedicated sample with constant hydrogen amount. Also the LIDS signal evaluation procedure is described in detail and the detection limits for different conditions in the TEXTOR tokamak are estimated.

  20. Development of the Potassium-Argon Laser Experiment (KArLE) Instrument for In Situ Geochronology

    Science.gov (United States)

    Cohen, Barbara A.; Li, Z.-H.; Miller, J. S.; Brinckerhoff, W. B.; Clegg, S. M.; Mahaffy, P. R.; Swindle, T. D.; Wiens, R. C.

    2012-01-01

    Absolute dating of planetary samples is an essential tool to establish the chronology of geological events, including crystallization history, magmatic evolution, and alteration. Traditionally, geochronology has only been accomplishable on samples from dedicated sample return missions or meteorites. The capability for in situ geochronology is highly desired, because it will allow one-way planetary missions to perform dating of large numbers of samples. The success of an in situ geochronology package will not only yield data on absolute ages, but can also complement sample return missions by identifying the most interesting rocks to cache and/or return to Earth. In situ dating instruments have been proposed, but none have yet reached TRL 6 because the required high-resolution isotopic measurements are very challenging. Our team is now addressing this challenge by developing the Potassium (K) - Argon Laser Experiment (KArLE) under the NASA Planetary Instrument Definition and Development Program (PIDDP), building on previous work to develop a K-Ar in situ instrument [1]. KArLE uses a combination of several flight-proven components that enable accurate K-Ar isochron dating of planetary rocks. KArLE will ablate a rock sample, determine the K in the plasma state using laser-induced breakdown spectroscopy (LIBS), measure the liberated Ar using quadrupole mass spectrometry (QMS), and relate the two by the volume of the ablated pit using an optical method such as a vertical scanning interferometer (VSI). Our preliminary work indicates that the KArLE instrument will be capable of determining the age of several kinds of planetary samples to +/-100 Myr, sufficient to address a wide range of geochronology problems in planetary science.

  1. Laser subepithelial keratomileusis for myopia of -6 to -10 diopters with astigmatism with the MEL60 laser.

    Science.gov (United States)

    Bilgihan, Kamil; Hondur, Ahmet; Hasanreisoglu, Berati

    2004-01-01

    To evaluate the efficacy, predictability, and safety of laser subepithelial keratomileusis (LASEK) for treatment of high myopia with astigmatism. LASEK was performed in 61 eyes of 36 consecutive patients with myopic spherical equivalent refraction of -6.00 to -10.00 D using the Aesculap-Meditec MEL60 excimer laser. Data were collected prospectively with a follow-up of 6 to 17 months. Main outcome measures recorded were UCVA, BSCVA, residual refractive error, corneal haze, and complications. Ninety-six percent of eyes achieved 20/40 or better UCVA at 1 month. At 12 months, 64% of eyes achieved 20/20 and 92% achieved 20/40 or better UCVA. Two eyes lost 2 lines of BSCVA at 6 or 12 months. Accuracy of correction was +/- 0.50 D from emmetropia in 82% of eyes, and +/- 1.00 D in 90% at 12 months. No eye showed more than grade 1 haze. Grade 1 haze was observed in three eyes at 12 months. One patient had mild postoperative keratitis, which was successfully treated. LASEK with the Aesculap-Meditec MEL60 excimer laser appeared to be safe, effective, and highly predictable in treating high myopia.

  2. Intraoperative perception and sensation in laser in situ keratomileusis (LASIK).

    Science.gov (United States)

    Srivannaboon, Sabong; Chansue, Ekktet

    2004-04-01

    To investigate intraoperative perception and sensation during Laser in situ Keratomileusis (LASIK). Sixty patients with uneventful LASIK were included. All procedures were performed by one surgeon with one technique. Any patient with intra-operative complications was excluded. The patients were asked to fill in the subjective evaluation form regarding their perception and sensation during the operation. Twenty-nine patients (48%) reported no pain and twenty-six patients (43%) reported no burning sensation during the surgery. Nineteen patients (32%) reported no light perception during the suction period of microkeratome. There was no correlation between duration of the suction and no light perception (R2 0.01). Thirty-four patients (56%) reported no trouble in maintaining visual fixation at the red light during the laser treatment. Ten patients (16%) reported they could clearly see the movement during the surgery and 5 out of 10 patients (50% of 16%) reported visual frightening. Fifty cases (84%) reported no visual frightening during the surgery after reassurance of the visual experience by the surgeon before the surgery. Patients undergoing LASIK may experience different visual perceptions. Reassurance of the intraoperative perception and sensation before the surgery can reduce the visual frightening.

  3. 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)

  4. 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)

  5. Development of laser materials processing and laser metrology techniques

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Chung, Chin Man; Kim, Jeong Mook; Kim, Min Suk; Kim, Kwang Suk; Baik, Sung Hoon; Kim, Seong Ouk; Park, Seung Kyu

    1997-09-01

    The applications of remote laser materials processing and metrology have been investigated in nuclear industry from the beginning of laser invention because they can reduce the risks of workers in the hostile environment by remote operation. The objective of this project is the development of laser material processing and metrology techniques for repairing and inspection to improve the safety of nuclear power plants. As to repairing, we developed our own laser sleeve welding head and innovative optical laser weld monitoring techniques to control the sleeve welding process. Furthermore, we designed and fabricated a 800 W Nd:YAG and a 150 W Excimer laser systems for high power laser materials processing in nuclear industry such as cladding and decontamination. As to inspection, we developed an ESPI and a laser triangulation 3-D profile measurement system for defect detection which can complement ECT and UT inspections. We also developed a scanning laser vibrometer for remote vibration measurement of large structures and tested its performance. (author). 58 refs., 16 tabs., 137 figs

  6. Bound-bound transitions in the emission spectra of Ba+-He excimer

    Science.gov (United States)

    Moroshkin, P.; Kono, K.

    2016-05-01

    We present an experimental and theoretical study of the emission and absorption spectra of the Ba+ ions and Ba+*He excimer quasimolecules in the cryogenic Ba-He plasma. We observe several spectral features in the emission spectrum, which we assign to the electronic transitions between bound states of the excimer correlating to the 6 2P3 /2 and 5 2D3 /2 ,5 /2 states of Ba+. The resulting Ba+(5 2DJ) He is a metastable electronically excited complex with orbital angular momentum L =2 , thus expanding the family of known metal-helium quasimolecules. It might be suitable for high-resolution spectroscopic studies and for the search for new polyatomic exciplex structures.

  7. Dependence of fracture toughness of molybdenum laser welds on dendritic spacing and in situ titanium additions

    International Nuclear Information System (INIS)

    Jellison, J.L.

    1979-01-01

    The fracture toughness of molybdenum welds has been improved by in situ gettering of oxygen by means of physically deposited titanium. The addition of titanium suppressed brittle intergranular fracture. Pulsed laser welds (both Nd:YAG and CO 2 ) exhibited superior toughness to that of continuous wave CO 2 laser welds. Also, welds of vacuum arc remelted grades were tougher than those of sintered molybdenum. However, weld toughness could not be correlated with either oxygen or carbon content

  8. 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.

  9. 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.

  10. Carbon nanotube formation by laser direct writing

    International Nuclear Information System (INIS)

    Wu, Y.-T.; Su, H.-C.; Tsai, C.-M.; Liu, K.-L.; Chen, G.-D.; Huang, R.-H.; Yew, T.-R.

    2008-01-01

    This letter presents carbon nanotube (CNT) formation by laser direct writing using 248 nm KrF excimer pulsed laser in air at room temperature, which was applied to irradiate amorphous carbon (a-C) assisted by Ni catalysts underneath for the transformation of carbon species into CNTs. The CNTs were synthesized under appropriate combination of laser energy density and a-C thickness. The growth mechanism and key parameters to determine the success of CNT formation were also discussed. The demonstration of the CNT growth by laser direct writing in air at room temperature opens an opportunity of in-position CNT formation at low temperatures

  11. In situ investigation of formation of self-assembled nanodomain structure in lithium niobate after pulse laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shur, V. Ya.; Kuznetsov, D. K.; Mingaliev, E. A.; Yakunina, E. M.; Lobov, A. I.; Ievlev, A. V. [Ferroelectric Laboratory, Institute of Physics and Applied Mathematics, Ural State University, Lenin Ave. 51, Ekaterinburg 620083 (Russian Federation)

    2011-08-22

    The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation was studied by in situ optical observation. The average periods of the structures are much less than the sizes of the laser spots. The polarization reversal occurs through covering of the whole irradiated area by the nets of the spatially separated nanodomain chains and microdomain rays--''hatching effect.'' The main stages of the anisotropic nanodomain kinetics: nucleation, growth, and branching, have been singled out. The observed abnormal domain kinetics was attributed to the action of the pyroelectric field arising during cooling after laser heating.

  12. 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.

  13. 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.

  14. Laser cladding in-situ carbide particle reinforced Fe-based composite coatings with rare earth oxide addition

    Institute of Scientific and Technical Information of China (English)

    吴朝锋; 马明星; 刘文今; 钟敏霖; 张红军; 张伟明

    2009-01-01

    Particulate reinforced metal matrix composite(PR-MMC) has excellent properties such as good wear resistance,corrosion resistance and high temperature properties.Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles.Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements,was favorable for the formation of in-situ synthesized carbide particles.In this paper,rare earth oxide(RE2O3) was added into t...

  15. The spatial thickness distribution of metal films produced by large area pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, Nini; Schou, Jørgen; Linderoth, Søren

    2007-01-01

    Thin films of metals have been deposited in the large-area Pulsed Laser Deposition (PLD) Facility at Riso National Laboratory. Thin films of Ag and Ni were deposited with laser pulses from an excimer laser at 248 nm with a rectangular beam spot at a fluence of 10 J/cm(2) on glass substrates of 127...

  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. In situ Sr/Sr investigation of igneous apatites and carbonates using laser-ablation MC-ICP-MS

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Simonetti, A.; Stevenson, R.K.

    2003-01-01

    In situ Sr isotopic compositions of coexisting apatite and carbonate for carbonatites from the Sarfartoq alkaline complex, Greenland, have been determined by laser-ablation multicollector inductively coupled plasma mass spectrometry. This study is the first to examine the extent of Sr isotopic ho...

  18. 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.

  19. Kinetic studies following state-selective laser excitation

    International Nuclear Information System (INIS)

    Keto, J.W.

    1991-01-01

    During the past year, we have made measurements of state-to-state energy transfer cross sections and radiative lifetimes for Xe*(6p,6p',7p) and Kr*(5p) states in xenon and krypton buffer gases. These results are relevant to kinetic models of both excimer lasers and the infrared xenon laser; and they are a significant improvement in the precision of the known radiative lifetimes. 3 refs., 2 figs., 2 tabs

  20. IN SITU Deposition of Fe-TiC Nanocomposite on Steel by Laser Cladding

    Science.gov (United States)

    Razavi, Mansour; Rahimipour, Mohammad Reza; Ganji, Mojdeh; Ganjali, Mansoreh; Gangali, Monireh

    The possibility of deposition of Fe-TiC nanocomposite on the surface of carbon steel substrate with the laser coating method had been investigated. Mechanical milling was used for the preparation of raw materials. The mixture of milled powders was used as a coating material on the substrate steel surface and a CO2 laser was used in continuous mode for coating. Microstructural studies were performed by scanning electron microscopy. Determinations of produced phases, crystallite size and mean strain have been done by X-ray diffraction. The hardness and wear resistance of coated samples were measured. The results showed that the in situ formation of Fe-TiC nanocomposite coating using laser method is possible. This coating has been successfully used to improve the hardness and wear resistance of the substrate so that the hardness increased by about six times. Coated iron and titanium carbide crystallite sizes were in the nanometer scale.

  1. Deposition and characterization of ITO films produced by laser ablation at 355 nm

    DEFF Research Database (Denmark)

    Holmelund, E.; Thestrup Nielsen, Birgitte; Schou, Jørgen

    2002-01-01

    Indium tin oxide (ITO) films have been deposited by pulsed laser deposition (PLD) at 355 nm. Even though the absorption of laser light at the wavelength 355 nm is much smaller than that of the standard excimer lasers for PLD at 248 nm and 193 nm, high-quality films can be produced. At high fluence...

  2. An automated, noncontact laser profile meter for measuring soil roughness in situ

    International Nuclear Information System (INIS)

    Bertuzzi, P.; Caussignac, J.M.; Stengel, P.; Morel, G.; Lorendeau, J.Y.; Pelloux, G.

    1990-01-01

    This paper describes a new optical technique for measuring in situ soil surface roughness profiles using a laser profile meter. The described method uses a low-power HeNe (helium-neon) laser as a laser source and a matrix-array detector, as the laser image. The matrix-array detector gives a defect-of-focus laser image of the soil. Soil elevation is measured by projecting a laser beam normally onto the soil surface and measuring the ratio (Ir/It) on the matrix-array detector between the referenced intensity of the return Laser beam (Ir), measured by the central cell of the detector and the total intensity (It), measured by all the cells of the detector. The measured profile leads to 1001 sampled values (volt, range 0 to 10 V) of the surface height profile, at a constant increment of 0.002 m, registered automatically on a microcomputer. A calibration is made in the laboratory in order to convert the electrical measurements into elevation data. The method is universal and can be adapted to different scales of soil surface roughness. Changing the scale is done by changing the lens. Tests were carried out to improve this method for field use and to compare this technique with a method of reference. This technique is considerably quicker and causes no disturbance to the soil. The accuracy on height measurement depends on the choice of the lens. The small focal lens is convenient for smooth soil surfaces. The accuracy on height measurement is less than 0.75 mm. The wide focal lens is convenient for rough soil surfaces. The accuracy on height measurement is estimated at about 1.0 to 1.5 mm

  3. 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...

  4. Laser- and UV-assisted modification of polystyrene surfaces for control of protein adsorption and cell adhesion

    International Nuclear Information System (INIS)

    Pfleging, Wilhelm; Torge, Maika; Bruns, Michael; Trouillet, Vanessa; Welle, Alexander; Wilson, Sandra

    2009-01-01

    An appropriate choice of laser and process parameters enables new approaches for the fabrication of polymeric lab-on-chip devices with integrated functionalities. We will present our current research results in laser-assisted modification of polystyrene (PS) with respect to the fabrication of polymer devices for cell culture applications. For this purpose laser micro-patterning of PS and subsequent surface functionalization was investigated as function of laser and process parameters. A high power ArF-excimer laser radiation source with a pulse length of 19 ns as well as a high repetition ArF-excimer laser source with a pulse length of 5 ns were used in order to study the influence of laser pulse length on laser-induced surface oxidation. The change in surface chemistry was characterized by X-ray photoelectron spectroscopy and contact angle measurements. The difference between laser-assisted modification versus UV-lamp assisted modification was investigated. A photolytic activation of specific areas of the polymer surface and subsequent oxidization in oxygen or ambient air leads to a chemically modified polymer surface bearing carboxylic acid groups well-suited for controlled competitive protein adsorption or protein immobilization. Finally, distinct areas for cell growth and adhesion are obtained

  5. Reactivation of presumed adenoviral keratitis after laser in situ keratomileusis.

    Science.gov (United States)

    Safak, Nilgün; Bilgihan, Kamil; Gürelik, Gökhan; Ozdek, Sengül; Hasanreisoğlu, Berati

    2002-04-01

    We report a patient with reactivation of presumed adenoviral keratoconjunctivitis after laser in situ keratomileusis (LASIK) to correct high myopia. The preoperative refraction was -13.00 diopters (D) in the right eye and -14.00 D in the left eye, and the best corrected visual acuity was 20/20 in both eyes. On the first postoperative day, mild conjunctival hyperemia and multiple subepithelial infiltrations localized in the flap zone consistent with adenoviral keratoconjunctivitis were seen. After prompt treatment, the lesions resolved. As a consequence, LASIK successfully corrected the high myopia. Adenoviral keratoconjunctivitis can be reactivated after LASIK, unlike after photorefractive keratectomy, despite the absence of symptomatic and clinical findings before the procedure.

  6. In situ growth of p and n-type graphene thin films and diodes by pulsed laser deposition

    KAUST Repository

    Sarath Kumar, S. R.; Nayak, Pradipta K.; Hedhili, Mohamed N.; Khan, M. A.; Alshareef, Husam N.

    2013-01-01

    We report the in situ growth of p and n-type graphene thin films by ultraviolet pulsed laser deposition in the presence of argon and nitrogen, respectively. Electron microscopy and Raman studies confirmed the growth, while temperature dependent

  7. 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.

  8. Tritium recovery from co-deposited layers using 193-nm laser

    Science.gov (United States)

    Shu, W. M.; Kawakubo, Y.; Nishi, M. F.

    Recovery of tritium from co-deposited layers formed in deuterium-tritium plasma operations of the TFTR (Tokamak Fusion Test Reactor) was investigated by the use of an ArF excimer laser operating at the wavelength of 193 nm. At the laser energy density of 0.1 J/cm2, a transient spike of the tritium-release rate was observed at initial irradiation. Hydrogen isotopes were released in the form of hydrogen-isotope molecules during the laser irradiation in vacuum, suggesting that tritium can be recovered readily from the released gases. In a second experiment, hydrogen (tritium) recovery from the co-deposited layers on JT-60 tiles that had experienced hydrogen-plasma operations was investigated by laser ablation with a focused beam of the excimer laser. The removal rate of the co-deposited layers was quite low when the laser energy density was smaller than the ablation threshold (1.0 J/cm2), but reached 1.1 μm/pulse at the laser energy density of 7.6 J/cm2. The effective absorption coefficient in the co-deposited layers at the laser wavelength was determined to be 1.9 μm-1. The temperature of the surface during the irradiation at the laser energy density of 0.5 J/cm2 was measured on the basis of Planck's law of radiation, and the maximum temperature during the irradiation decreased from 3570 K at the initial irradiation to 2550 K at the 1000th pulse of the irradiation.

  9. Application of laser resonance scattering to the study of high-temperature plasma-wall interaction

    International Nuclear Information System (INIS)

    Maeda, Mitsuo; Muraoka, Katsunori; Hamamoto, Makoto; Akazaki, Masanori; Miyazoe, Yasushi

    1981-01-01

    Studies on laser resonance scattering and its application to the study of high-temperature plasma-wall interaction are reviewed. The application of dye laser beam to resonant scattering method has been developed. This method is able to detect low density atoms. The fluorescent photon counts can be estimated for a two-level system and a three-level system. The S/N ratio, Which is in close connection with the detection limit, has been estimated. The doppler effect due to the thermal motion of atoms is taken into consideration. The calibration of the absolute number of atoms is necessary. Tunable coherent light is used as the light source for resonance scattering method. This is able to excite atoms strongly and to increase the detection efficiency. As dye lasers, a N 2 laser, a YAG laser, and a KrF excimer laser have been studied. In VUV region, rare gas or rare gas halide lasers can be used. The strong output power can be expected when the resonance lines of atoms meet the synchronizing region of the excimer laser. The resonance scattering method is applied to the detection of impurity metal atoms in plasma. The studies of laser systems for the detection of hydrogen atoms are also in progress. (Kato, T.)

  10. In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel.

    Science.gov (United States)

    Lepri, Taísa Penazzo; Scatolin, Renata Siqueira; Colucci, Vivian; De Alexandria, Adílis Kalina; Maia, Lucianne Cople; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2014-08-01

    The present study aimed to evaluate in situ the effect of CO2 laser irradiation to control the progression of enamel erosive lesions. Fifty-six slabs of bovine incisors enamel (5 × 3 × 2.5 mm(3) ) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO2 laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO2 laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2-day lead-in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross-over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three-way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO2 laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO2 laser irradiation was performed. There was no difference in enamel wear between specimens CO2 -laser irradiated and non-irradiated (P = 0.513). Under intraoral conditions, CO2 laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. © 2014 Wiley Periodicals, Inc.

  11. 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)

  12. Optimization of KrF laser ablation parameters for in-situ growth of Y1Ba2Cu3O7-δ thin films

    International Nuclear Information System (INIS)

    Pinto, R.; Pai, S.P.; Souza, C.P. d'; Gupta, L.C.; Vijayaraghavan, R.; Kumar, D.; Sharon, M.

    1992-01-01

    Using a KrF pulsed excimer laser, various interrelated deposition parameters governing the quality of laser-ablated Y 1 Ba 2 Cu 3 O 1-δ (123) thin films have been systematically studied. Modification of the 123 target with increasing laser exposure has been found to affect the plume stability, and the axis of the plume has been found to shift slowly towards the direction of the laser beam. Small laser spots exposing a relatively large diameter annular track of the rotating target have been found to give better plume stability than larger spots exposing the same diameter track. Because of better plume stability and larger plume expansion, smaller laser spots have been found to give significantly better quality 123 films as compared with large spots under optimised growth conditions. The effects of varying O 2 pressure and target-substrate distance have been found to be similar and the location of the substrates at or close to the tip of the plume has been found to be important for the realization of film stoichiometry and high quality. Results have shown that under optimised conditions of 3 J cm -2 fluence, 200 mTorr O 2 pressure and 4.5 cm target-substrate distance, films with Tc = 90 K, D T ∝ 1 K and critical current density, J c ≥ 2x10 6 A cm -2 at 77 K can be reproducibly realized on MgO substrates with small (3 mm x 0.8 mm) laser spots. (orig.)

  13. Choice of the laser wavelength for a herpetic keratitis treatment

    Science.gov (United States)

    Razhev, Alexander M.; Bagayev, Sergei N.; Chernikh, Valery V.; Kargapoltsev, Evgeny S.; Trunov, Alexander; Zhupikov, Andrey A.

    2002-06-01

    For the first time the effect of the UV laser radiation to human eye cornea with herpetic keratitis was experimentally investigated. In experiments the UV radiation of ArF (193 nm), KrCl (223 nm), KrF (248 nm) excimer lasers were used. Optimal laser radiation parameters for the treatment of the herpetic keratitis were determined. The immuno-biochemical investigations were carried out and the results of clinical trials are presented. The maximum ablation rate was obtained for the 248 nm radiation wavelength. The process of healing was successful but in some cases the haze on the surface of the cornea was observed. When used the 193 nm radiation wavelength the corneal surface was clear without any hazes but the epithelization process was slower than for 248 nm wavelength and in some cases the relapse was occurred. The best results for herpetic keratitis treatment have been achieved by utilizing the 223 nm radiation wavelength of the KrCl excimer laser. The use of the 223 nm radiation wavelength allows treating the herpetic keratitis with low traumatic process of ablation and provides high quality of corneal surface.

  14. Development of in-situ laser based cutting technique for shock absorber rear nut in pressurized heavy water reactors. CP-2.1

    International Nuclear Information System (INIS)

    Vishwakarma, S.C.; Jain, R.K.; Upadhyaya, B.N.; Choubey, Ambar; Agrawal, D.K.; Oak, S.M.

    2007-01-01

    We have developed a laser based cutting technique for shock absorber rear nuts in pressurized heavy water reactors (PHWRs). This technique has been successfully used for in-situ laser cutting at RAPS-3 reactor. The technique consists of a motorized compact fixture, which holds a fiber optic beam delivery cutting nozzle and can be operated remotely

  15. Self-sustaining nuclear pumped laser-fusion reactor experiment

    International Nuclear Information System (INIS)

    Boody, F.P.; Choi, C.K.; Miley, G.H.

    1977-01-01

    The features of a neutron feedback nuclear pumped (NFNP) laser-fusion reactor equipment were studied with the intention of establishing the feasibility of the concept. The NFNP laser-fusion concept is compared schematically to electrically pumped laser fusion. The study showed that, once a method of energy storage has been demonstrated, a self-sustaining fusion-fission hybrid reactor with a ''blanket multiplication'' of two would be feasible using nuclear pumped Xe F* excimer lasers having efficiencies of 1 to 2 percent and D-D-T pellets with gains of 50 to 100

  16. Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Theppakuttaikomaraswamy, Senthil P. [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the aim of this work to enhance the understanding and application of Michelson interferometry principle for the in-situ diagnostics of the machining depth on the sub-micron and micron scales. micromachining is done on two different materials and a comprehensive investigation is done to control the width and depth of the machined feature. To control the width of the feature, laser micromachining is done on copper and a detailed analysis is performed. The objective of this experiment is to make a precision mask for sputtering with an array of holes on it using an Nd:YAG laser of 532 nm wavelength. The diameter of the hole is 50 μm and the spacing between holes (the distance between the centers) is 100 μm. Michelson interferometer is integrated with a laser machining system to control the depth of machining. An excimer laser of 308 nm wavelength is used for micromachining. A He-Ne laser of 632.8 nm wavelength is used as the light source for the interferometer. Interference patterns are created due to the change in the path length between the two interferometer arms. The machined depth information is obtained from the interference patterns on an oscilloscope detected by a photodiode. To compare the predicted depth by the interferometer with the true machining depth, a surface profilometer is used to measure the actual machining depth on the silicon. It is observed that the depths of machining obtained by the surface profile measurement are in accordance with the interferometer

  17. Evaluating Acoustic Emission Signals as an in situ process monitoring technique for Selective Laser Melting (SLM)

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Karl A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Candy, Jim V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Guss, Gabe [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mathews, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-14

    In situ real-time monitoring of the Selective Laser Melting (SLM) process has significant implications for the AM community. The ability to adjust the SLM process parameters during a build (in real-time) can save time, money and eliminate expensive material waste. Having a feedback loop in the process would allow the system to potentially ‘fix’ problem regions before a next powder layer is added. In this study we have investigated acoustic emission (AE) phenomena generated during the SLM process, and evaluated the results in terms of a single process parameter, of an in situ process monitoring technique.

  18. [Hyperopic Laser-in-situ-Keratomileusis after trifocal intraocular lens implantation : Aberration-free femto-Laser-in-situ-Keratomileusis treatment after implantation of a diffractive, multifocal, toric intraocular lens-case analysis].

    Science.gov (United States)

    Hemkeppler, E; Böhm, M; Kohnen, T

    2018-05-29

    A 52-year-old highly myopic female patient was implanted with a multifocal, diffractive, toric intraocular lens because of the wish to be independent of eyeglasses. Despite high-quality, extensive preoperative examinations, a hyperopic refractive error remained postoperatively, which led to the patient's dissatisfaction. This error was treated with Laser-in-situ-Keratomileusis (LASIK). After corneal LASIK treatment and implantation of a diffractive toric multifocal intraocular lens the patient showed a good postoperative visual result without optical phenomena.

  19. Comparison of the effects of cylindrical correction with and without iris recognition technology in wavefront laser-assisted in situ keratomileusis.

    Science.gov (United States)

    Wang, Tsung-Jen; Lin, Yu-Huang; Chang, David C-K; Chou, Hsiu-Chu; Wang, I-Jong

    2012-04-01

      To analyse the magnitude of cylindrical corrections over which cyclotorsion compensation with iris recognition (IR) technology is beneficial during wavefront laser-assisted in situ keratomileusis.   A retrospectively comparative case series.   Fifty-four eyes that underwent wavefront laser-assisted in situ keratomileusis without IR (non-IR group) and 53 eyes that underwent wavefront laser-assisted in situ keratomileusis with IR (IR group) were recruited.   Subgroup analysis based on baseline astigmatism were: a low degree of astigmatism (≥1.00 D to <2.00 D), a moderate degree of astigmatism (≥2.00 D to <3.00 D) and a high degree of astigmatism (≥3.00 D).   Vector and non-vector analyses were used for comparison.   The mean cylinder was -1.89 ± 0.76 D in the non-IR group and -2.00 ± 0.77 D in the IR group. Postoperatively, 38 eyes (74.50%) in the IR group and 31 eyes (57.50%) in the non-IR group were within ± 0.50 D of the target induced astigmatism vector (P = 0.063). The difference vector was 0.49 ± 0.28 in the IR group and 0.63 ± 0.40 in the non-IR group (P = 0.031). In the analysis of subgroups, the magnitude of error was significantly lower in the moderate IR subgroup than that of the moderate non-IR subgroup (P = 0.034). Furthermore, the moderate IR subgroup had a lower mean difference vector (P = 0.0078) and a greater surgically induced astigmatism (P = 0.036) than those of the moderate non-IR group.   Wavefront laser-assisted in situ keratomileusis for the treatment of astigmatism using IR technology was effective and accurate for the treatment of myopic astigmatism. © 2011 The Authors. Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists.

  20. In situ process monitoring in selective laser sintering using optical coherence tomography

    Science.gov (United States)

    Gardner, Michael R.; Lewis, Adam; Park, Jongwan; McElroy, Austin B.; Estrada, Arnold D.; Fish, Scott; Beaman, Joseph J.; Milner, Thomas E.

    2018-04-01

    Selective laser sintering (SLS) is an efficient process in additive manufacturing that enables rapid part production from computer-based designs. However, SLS is limited by its notable lack of in situ process monitoring when compared with other manufacturing processes. We report the incorporation of optical coherence tomography (OCT) into an SLS system in detail and demonstrate access to surface and subsurface features. Video frame rate cross-sectional imaging reveals areas of sintering uniformity and areas of excessive heat error with high temporal resolution. We propose a set of image processing techniques for SLS process monitoring with OCT and report the limitations and obstacles for further OCT integration with SLS systems.

  1. Advanced lasers for fusion

    International Nuclear Information System (INIS)

    Krupke, W.F.; George, E.V.; Haas, R.A.

    1979-01-01

    Laser drive systems' performance requirements for fusion reactors are developed following a review of the principles of inertial confinement fusion and of the technical status of fusion research lasers (Nd:glass; CO 2 , iodine). These requirements are analyzed in the context of energy-storing laser media with respect to laser systems design issues: optical damage and breakdown, medium excitation, parasitics and superfluorescence depumping, energy extraction physics, medium optical quality, and gas flow. Three types of energy-storing laser media of potential utility are identified and singled out for detailed review: (1) Group VI atomic lasers, (2) rare earth solid state hybrid lasers, and (3) rare earth molecular vapor lasers. The use of highly-radiative laser media, particularly the rare-gas monohalide excimers, are discussed in the context of short pulse fusion applications. The concept of backward wave Raman pulse compression is considered as an attractive technique for this purpose. The basic physics and device parameters of these four laser systems are reviewed and conceptual designs for high energy laser systems are presented. Preliminary estimates for systems efficiencies are given. (Auth.)

  2. In situ growth monitoring of AlGaN/GaN distributed Bragg reflectors at 530 nm using a 633 nm laser

    Energy Technology Data Exchange (ETDEWEB)

    Wen Feng; Huang Lirong; Jiang Bo; Tong Liangzhu; Xu Wei; Liu Deming, E-mail: hlr5649@163.co [Wuhan National Laboratory for Optoelectronics, College of Opto-Electronics Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2010-09-15

    The metal-organic chemical vapor deposition (MOCVD) growth of AlGaN/GaN distributed Bragg reflectors (DBR) with a reflection peak at 530 nm was in situ monitored using 633 nm laser reflectometry. Evolutions of in situ reflected reflectivity for different kinds of AlGaN/GaN DBR were simulated by the classical transfer matrix method. Two DBR samples, which have the same parameters as the simulated structures, were grown by MOCVD. The simulated and experimental results show that it is possible to evaluate the DBR parameters from the envelope shape of the in situ reflectivity spectrum. With the help of the 633 nm laser reflectometry, a DBR light emitting diode (LED) was grown. The room temperature photoluminescence spectra show that the reflection peak of the DBR in the LED is within the design region. (semiconductor devices)

  3. Update on Development of the Potassium-Argon Laser Experiment (KArLE) Instrument for In Situ Geochronology

    Science.gov (United States)

    Cohen, Barbara A.; Li, Z.-H.; Miller, J. S.; Brinckerhoff, W. B.; Clegg, S. M.; Mahaffy, P. R.; Swindle, T. D.; Wiens, R. C.

    2013-01-01

    Absolute dating of planetary samples is an essential tool to establish the chronology of geological events, including crystallization history, magmatic evolution, and alteration. We are addressing this challenge by developing the Potassium (K) -- Argon Laser Experiment (KArLE), building on previous work to develop a K-Ar in situ instrument. KArLE ablates a rock sample, determines the K in the plasma state using laser-induced breakdown spectroscopy (LIBS), measures the liberated Ar using quadrupole mass spectrometry (QMS), and relates the two by the volume of the ablated pit using laser confocal microscopy (LCM). Our goal is for the KArLE instrument to be capable of determining the age of several kinds of planetary samples to address a wide range of geochronolgy problems in planetary science.

  4. Establishing reliable good initial quantum efficiency and in-situ laser cleaning for the copper cathodes in the RF gun

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, F., E-mail: zhoufeng@slac.stanford.edu; Sheppard, J.C.; Vecchione, T.; Jongewaard, E.; Brachmann, A.; Corbett, J.; Gilevich, S.; Weathersby, S.

    2015-05-21

    Establishing good initial quantum efficiency (QE) and reliable in-situ cleaning for copper cathode in the RF gun is of critical importance for the RF gun operations. Recent studies on the SLAC RF gun test bed indicated that the pre-cleaning (plasma cleaning) in the test chamber followed by copper cathode exposure to air for cathode change leads to a very low initial QE in the RF gun, and also demonstrated that without the pre-cleaning good initial QE >4×10{sup −5} can be routinely achieved in the RF gun with the cathodes of QE <1×10{sup −7} measured in the test chamber. QE can decay over the time in the RF gun. The in-situ laser cleaning technique for copper cathodes in the RF gun is established and refined in comparison to previous cleaning at the linac coherent light source, resulting in an improved QE and emittance evolutions. The physics of the laser cleaning process is discussed. It is believed that the reflectivity change is one of the major factors for the QE boost with the laser cleaning.

  5. Quantitative laser-induced breakdown spectroscopy of potassium for in-situ geochronology on Mars

    Energy Technology Data Exchange (ETDEWEB)

    Stipe, Christopher B., E-mail: stipec@seattleu.edu [Department of Mechanical Engineering, Seattle University, Seattle, WA 98122 (United States); Guevara, Edward; Brown, Jonathan [Department of Mechanical Engineering, Seattle University, Seattle, WA 98122 (United States); Rossman, George R. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)

    2012-04-15

    Laser-induced breakdown spectroscopy is explored for the development of an in-situ K-Ar geochronology instrument for Mars. Potassium concentrations in standard basaltic glasses and equivalent rock samples in their natural form are quantified using the potassium doublet at 766.49 and 769.90 nm. Measurement precision varies from 0.5 to 5.5 (% RSD) over the 3.63% to 0.025% potassium by weight for the standard samples, and little additional precision is achieved above 20 laser shots at 5 locations. For the glass standards, the quantification limits are 920 and 66 ppm for non-weighted and weighted calibration methods, respectively. For the basaltic rocks, the quantification limits are 2650 and 328 ppm for the non-weighted and weighted calibration methods, respectively. The heterogeneity of the rock samples leads to larger variations in potassium signal; however, normalizing the potassium peak by base area at 25 locations on the rock improved calibration accuracy. Including only errors in LIBS measurements, estimated age errors for the glasses range from approximately {+-} 30 Ma for 3000 Ma samples to {+-} 2 Ma for 100 Ma samples. For the basaltic rocks, the age errors are approximately {+-} 120 Ma for 3000 Ma samples and {+-} 8 Ma for 100 Ma samples. - Highlights: Black-Right-Pointing-Pointer Measurement of basaltic glasses and rocks by laser-induced breakdown spectroscopy. Black-Right-Pointing-Pointer Quantification of potassium for K-Ar dating. Black-Right-Pointing-Pointer Development of an instrument for in-situ geochronology on Mars. Black-Right-Pointing-Pointer Detection limit is 35 ppm, relative standard deviations range from 0.5% to 5.5%. Black-Right-Pointing-Pointer Estimated errors for the glass standards range from {+-} 30 Ma for 3000 Ma and {+-} 2 Ma for 100 Ma; estimated errors for the basaltic rocks range from {+-} 120 Ma for 3000 Ma and {+-} 8 Ma for 100 Ma.

  6. In-situ observation of recrystallization in an AlMgScZr alloy using confocal laser scanning microscopy

    International Nuclear Information System (INIS)

    Taendl, J.; Nambu, S.; Orthacker, A.; Kothleitner, G.; Inoue, J.; Koseki, T.; Poletti, C.

    2015-01-01

    In this work we present a novel in-situ approach to study the recrystallization behavior of age hardening alloys. We use confocal laser scanning microscopy (CLSM) at 400 °C to investigate the static recrystallization of an AlMg4Sc0.4Zr0.12 alloy in-situ. The results are combined with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses. It was found that CLSM is a powerful tool to visualize both the local initiation and temporal sequence of recrystallization. After fast nucleation and initial growth, the grain growth rate decreases and the grain boundary migration stops after some minutes due to Zener pinning from Al 3 (Sc,Zr) precipitates produced during the heat treatment. EBSD and TEM analyses confirm both the boundary movements and the particle-boundary interactions. - Highlights: • First time that CLSM is used to study recrystallization in-situ. • The start and end of recrystallization can be directly observed. • The procedure is easy to apply and requires only simple data interpretation. • In-situ observations on the surface correlate to modifications inside the bulk. • In-situ observations correlate to EBSD and EFTEM analyses.

  7. In-situ observation of recrystallization in an AlMgScZr alloy using confocal laser scanning microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Taendl, J., E-mail: johannes.taendl@tugraz.atl [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria); Nambu, S. [Department of Materials Engineering, The University of Tokyo, Tokyo 113-8656 (Japan); Orthacker, A.; Kothleitner, G. [Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Graz (Austria); Graz Center for Electron Microscopy, Graz (Austria); Inoue, J.; Koseki, T. [Department of Materials Engineering, The University of Tokyo, Tokyo 113-8656 (Japan); Poletti, C. [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria)

    2015-10-15

    In this work we present a novel in-situ approach to study the recrystallization behavior of age hardening alloys. We use confocal laser scanning microscopy (CLSM) at 400 °C to investigate the static recrystallization of an AlMg4Sc0.4Zr0.12 alloy in-situ. The results are combined with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses. It was found that CLSM is a powerful tool to visualize both the local initiation and temporal sequence of recrystallization. After fast nucleation and initial growth, the grain growth rate decreases and the grain boundary migration stops after some minutes due to Zener pinning from Al{sub 3}(Sc,Zr) precipitates produced during the heat treatment. EBSD and TEM analyses confirm both the boundary movements and the particle-boundary interactions. - Highlights: • First time that CLSM is used to study recrystallization in-situ. • The start and end of recrystallization can be directly observed. • The procedure is easy to apply and requires only simple data interpretation. • In-situ observations on the surface correlate to modifications inside the bulk. • In-situ observations correlate to EBSD and EFTEM analyses.

  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. Characterization of superconducting thin films deposited by laser ablation. Caracterisation de films minces supraconducteurs deposes par ablation laser

    Energy Technology Data Exchange (ETDEWEB)

    Sentis, M; Delaporte, P [I.M.F.M., 13 - Marseille (FR); Gerri, M; Marine, W [Aix-Marseille-2 Univ., 13-Marseille (FR). Centre Universitaire de Luminy

    1991-05-01

    Thin films of YBa{sub 2}Cu{sub 3}O{sub 7} are deposited by laser ablation on MgO and YSZ substrates. Deposits by infrared (I.R.) Nd: YAG are non stoechiometric. The films having the best superconductor qualities are deposited by ablation with an excimer U.V. laser ({lambda} = 308 nm). These films are epitaxiated with the c axis perpendicular to the substrate. The film quality depends on the substrate temperature, oxygen pressure and cooling speed.

  10. 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.

  11. Factors Influencing Intraocular Pressure Changes after Laser In Situ Keratomileusis with Flaps Created by Femtosecond Laser or Mechanical Microkeratome.

    Directory of Open Access Journals (Sweden)

    Meng-Yin Lin

    Full Text Available The aim of this study is to describe factors that influence the measured intraocular pressure (IOP change and to develop a predictive model after myopic laser in situ keratomileusis (LASIK with a femtosecond (FS laser or a microkeratome (MK. We retrospectively reviewed preoperative, intraoperative, and 12-month postoperative medical records in 2485 eyes of 1309 patients who underwent LASIK with an FS laser or an MK for myopia and myopic astigmatism. Data were extracted, such as preoperative age, sex, IOP, manifest spherical equivalent (MSE, central corneal keratometry (CCK, central corneal thickness (CCT, and intended flap thickness and postoperative IOP (postIOP at 1, 6 and 12 months. Linear mixed model (LMM and multivariate linear regression (MLR method were used for data analysis. In both models, the preoperative CCT and ablation depth had significant effects on predicting IOP changes in the FS and MK groups. The intended flap thickness was a significant predictor only in the FS laser group (P < .0001 in both models. In the FS group, LMM and MLR could respectively explain 47.00% and 18.91% of the variation of postoperative IOP underestimation (R2 = 0.47 and R(2 = 0.1891. In the MK group, LMM and MLR could explain 37.79% and 19.13% of the variation of IOP underestimation (R(2 = 0.3779 and 0.1913 respectively. The best-fit model for prediction of IOP changes was the LMM in LASIK with an FS laser.

  12. Preliminary design and estimate of capital and operating costs for a production scale application of laser decontamination technology

    International Nuclear Information System (INIS)

    Pang, Ho-ming; Edelson, M.C.

    1994-01-01

    The application of laser ablation technology to the decontamination of radioactive metals, particularly the surfaces of equipment, is discussed. Included is information related to the design, capital and operating costs, and effectiveness of laser ablation technology, based on commercial excimer and Nd:YAG lasers, for the decontamination of production scale equipment

  13. Diplopia after laser in situ keratomileusis (LASIK) in a patient with a history of strabismus.

    Science.gov (United States)

    Heinmiller, Laura J; Wasserman, Barry N

    2013-02-01

    In patients with a history of strabismus, refractive surgery can result in decompensation of ocular alignment, with subsequent diplopia. Refractive surgery in the management of strabismus has been described, although it remains controversial. We present a young adult with past history of strabismus surgery and new-onset diplopia after refractive surgery. Binocular diplopia was treated surgically with laser in situ keratomileusis. Copyright © 2013 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

  14. Advanced lasers for fusion applications

    International Nuclear Information System (INIS)

    Krupke, W.F.

    1978-11-01

    Projections indicate that MJ/MW laser systems, operating with efficiencies in escess of 1 percent, are required to drive laser fusion power reactors. Moreover, a premium in pellet performance is anticipated as the wavelength of the driver laser system is decreased. Short wavelength laser systems based on atomic selenium (lambda = 0.49μ), terbium molcular vapors (0.55μ), thulium doped dielectric solids (0.46μ), and on pulse compressions of KrF excimer laser radiaton (0.27μ) have been proposed and studied for this purpose. The technological scalability and efficiency of each of these systems is examined in this paper. All of these systems are projected to meet minimum systems requirements. Amont them, the pulse-compressed KrF system is projected to have the highest potential efficiency (6%) and the widest range of systems design options

  15. [Keratitis after laser in situ keratomileusis (LASIK). A different entity and treatment management].

    Science.gov (United States)

    Ahmed, Shakil; Ahmed, Hassan Javed; Holm, Lars Morten

    2014-12-15

    Keratitis after laser in situ keratomileusis (LASIK) is rare and challenging as patients may present with mild symptoms and initial management differs significantly. Post-LASIK keratitis is usually due to gram-positive bacteria or opportunistic/atypical microorganisms located beneath the corneal flap. Due to relative protective interface location it is necessary to lift the corneal flap for cultures and antibiotic irrigation. The case report demonstrates that post-LASIK keratitis requires prompt referral to ophthalmology department as correct initial management is pivotal for good visual outcome.

  16. Pressure dependence of emission intensity of rare-gas excimer light produced by silent discharge; Teikiatsu ryoiki ni okeru musei hoden reiki ki gas excimer hikari shutsuryoku no atsuryoku izonsei

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Y.; Tanaka, M.; Yukimura, K. [Doshisha University, Kyoto (Japan)

    1996-09-20

    To establish the pressure dependence of silent discharge excited rare gas excimer light emission, a vacua ultraviolet light was subjected to spectroscopic analysis at a pressure lower than 20kPa. Researches are under way to apply the discharge excited rare gas excimer lamp as a vacuum ultraviolet light source for the development of new materials and for the conservation of environments. When the pressure is as low as 1.8kPa or 4.4kPa, the emission has peaks at wavelengths centering on 147nm and 149nm, both of which are the resonance lines of the xenon atom. Excimer generation becomes prominent as the pressure increases, with the second continuum of light growing dominant at 35kPa to weaken relatively the resonance lines and the first continuum of light. In the first continuum, emission increases only at a suppressed rate, as compared with emission in the second continuum, due for instance to a collision caused relaxation process in which excimers are lost. In the case of xenon in the vicinity of 10-11kPa, the first continuum of light and the second continuum of light are approximately equal in emission intensity, producing a vacuum ultraviolet light source with a bandwidth relatively large for a single gas spectrum. 14 refs., 11 figs.

  17. New polymers containing BF2-benzoylacetonate groups. Synthesis, luminescence, excimer and exciplex formation

    International Nuclear Information System (INIS)

    Fedorenko, Elena V.; Mirochnik, Anatolii G.; Beloliptsev, Anton Yu.

    2017-01-01

    In the present study, a new synthetic method for the functionalization of polystyrene (PS) and (styrene-methyl methacrylate) copolymer has been developed. Using the new method, polymers containing BF 2 -benzoylacetonate groups have been obtained through double acylation by acetic anhydride with boron trifluoride. Luminescence of the produced polymers in solutions and films has been studied. Quantum yields of polymer solution luminescence are significantly higher than those of the low-molecular-weight analog – boron difluoride benzoylacetonate. For the polymer, in which styrene fragments are separated by methyl methacrylate groups, at low concentrations of the polymer in solution one observes the monomer luminescence of BF 2 -benzoylacetonate groups, while at high concentrations – the excimer luminescence. In case of PS-based polymers, in which BF 2 -benzoylacetonate groups and phenyl rings are not separated, in diluted solutions one observes the fluorescence of the intramolecular exciplexes, while at the concentration increase – the luminescence of intermolecular exciplexes. The ability of excimer formation is responsible for the increased photostability of the produced polymers. - Highlights: •Polymers containing BF 2 -benzoylacetonate groups have been synthesized. •Luminescence of the produced polymers in solutions and films has been studied. •Formation of excimers and exciplexes in solution has been revealed. •Formation of excimers in films increases their photostability.

  18. Polyfluorophore Excimers and Exciplexes as FRET Donors in DNA

    Science.gov (United States)

    Teo, Yin Nah; Kool, Eric T.

    2009-01-01

    We describe studies aimed at testing whether oligomeric exciplex- and excimer fluorophores conjugated to DNA have the potential to act as donors for energy transfer by the Förster mechanism. Oligodeoxyfluorosides (ODFs) are composed of stacked, electronically interacting fluorophores replacing the bases on a DNA scaffold. The monomer chromophores in the twenty tetramer-length ODFs studied here include pyrene (Y), benzopyrene (B), perylene (E), dimethylaminostilbene (D), and a nonfluorescent spacer (S); these are conjugated in varied combinations at the 3’ end of a 14mer DNA probe sequence. In the absence of an acceptor chromophore, many of the ODF-DNAs show broad, unstructured long-wavelength emission peaks characteristic of excimer and exciplex excited states, similar to what has been observed for unconjugated ODFs. Although such delocalized excited states have been widely studied, we know of no prior report of their use in FRET. We tested the ability of the twenty ODFs to donate energy to Cy5 and TAMRA dyes conjugated to a complementary strand of DNA, with these acceptors oriented either at the near or far end of the ODF-conjugated probes. Results showed that a number of the ODF fluorophores exhibited relatively efficient energy transfer characteristic of the Förster mechanism, as judged by drops in donor emission quantum yield and fluorescence lifetime, accompanied by increases in intensity of acceptor emission bands. Excimer/exciplex bands in the donors were selectively quenched while shorter-wavelength monomer emission stayed relatively constant, consistent with the notion that the delocalized excited states, rather than individual fluorophores, are the donors. Interestingly, only specific sequences of ODFs were able to act as donors, while others did not, even though their emission wavelengths were similar. The new FRET donors possess large Stokes shifts, which can be beneficial for multiple applications. In addition, all ODFs can be excited at a single

  19. Growth of micro-crystals in solution by in-situ heating via continuous wave infrared laser light and an absorber

    Science.gov (United States)

    Pathak, Shashank; Dharmadhikari, Jayashree A.; Thamizhavel, A.; Mathur, Deepak; Dharmadhikari, Aditya K.

    2016-01-01

    We report on growth of micro-crystals such as sodium chloride (NaCl), copper sulphate (CuSO4), potassium di-hydrogen phosphate (KDP) and glycine (NH2CH2COOH) in solution by in-situ heating using continuous wave Nd:YVO4 laser light. Crystals are grown by adding single walled carbon nanotubes (SWNT). The SWNTs absorb 1064 nm light and act as an in-situ heat source that vaporizes the solvent producing microcrystals. The temporal dynamics of micro-crystal growth is investigated by varying experimental parameters such as SWNT bundle size and incident laser power. We also report crystal growth without SWNT in an absorbing medium: copper sulphate in water. Even though the growth dynamics with SWNT and copper sulphate are significantly different, our results indicate that bubble formation is necessary for nucleation. Our simple method may open up new vistas for rapid growth of seed crystals especially for examining the crystallizability of inorganic and organic materials.

  20. Setting up and performance of a laser enhanced ionisation spectrometer

    International Nuclear Information System (INIS)

    Chandola, L.C.; Khanna, P.P.; Razvi, M.A.N.

    1990-01-01

    A laser enhanced ionisation (LEI) spectrometer has been successfuly set up around an excimer laser pumped dye laser. The performance of the spectrometer has been tested by analysing sodium in water solutions. A straight line working curve has been obtained in the concentration range of 1-1000 ng/ml of Na. The effect of parameters like laser power, ion collector electrode voltage and the load resistance on LEI signals has been investigated. The spectrometer is useful not only for analytical purposes but also for laser spectroscopic studies of species formed in flames, study of phenomenon of combustion etc. (author). 1 tab ., 10 figs., 5 refs

  1. Laser-assisted immobilization of colloid silver nanoparticles on polyethyleneterephthalate

    Czech Academy of Sciences Publication Activity Database

    Siegel, J.; Lyutakov, O.; Polívková, M.; Staszek, M.; Hubáček, Tomáš; Švorčík, V.

    2017-01-01

    Roč. 420, OCT (2017), s. 661-668 ISSN 0169-4332 R&D Projects: GA MŠk LM2015075 Institutional support: RVO:60077344 Keywords : silver nanoparticles * polyethyleneterephthalate * excimer laser * immobilization Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 3.387, year: 2016

  2. Survey on modern pulsed high power lasers

    International Nuclear Information System (INIS)

    Witte, K.J.

    1985-01-01

    The requirements to be met by lasers for particle acceleration are partially similar to those already known for fusion lasers. The power level wanted in both caes is up to 100 TW or even more. The pulse durations favourable for laser accelerators are in the range from 1 ps to 1000 ps whereas fusion lasers require several ns. The energy range for laser accelerators is thus correspondingly smaller than that for fusion lasers: 1-100 kJ versus several 100 kJ. The design criteria of lasers meeting the requirements are discussed in the following. The CO 2 , iodine, Nd:glass and excimer lasers are treated in detail. The high repetition rate aspect will not be particularly addressed since for the present generation of lasers the wanted rates of far above 1 Hz are completely out of scope. Moreover, for the demonstration of principle these rates are not needed. (orig./HSI)

  3. Processing of Dielectric Optical Coatings by Nanosecond and Femtosecond UV Laser Ablation

    International Nuclear Information System (INIS)

    Ihlemann, J.; Bekesi, J.; Klein-Wiele, J.H.; Simon, P.

    2008-01-01

    Micro processing of dielectric optical coatings by UV laser ablation is demonstrated. Excimer laser ablation at deep UV wavelengths (248 nm, 193 nm) is used for the patterning of thin oxide films or layer stacks. The layer removal over extended areas as well as sub-μm-structuring is possible. The ablation of SiO2, Al2O3, HfO2, and Ta2O5 layers and layer systems has been investigated. Due to their optical, chemical, and thermal stability, these inorganic film materials are well suited for optical applications, even if UV-transparency is required. Transparent patterned films of SiO2 are produced by patterning a UV-absorbing precursor SiOx suboxide layer and oxidizing it afterwards to SiO2. In contrast to laser ablation of bulk material, in the case of thin films, the layer-layer or layer-substrate boundaries act as predetermined end points, so that precise depth control and a very smooth surface can be achieved. For large area ablation, nanosecond lasers are well suited; for patterning with submicron resolution, femtosecond excimer lasers are applied. Thus the fabrication of optical elements like dielectric masks, pixelated diffractive elements, and gratings can be accomplished.

  4. Mid-infrared pulsed laser ablation of the arterial wall. Mechanical origin of "acoustic" wall damage and its effect on wall healing

    NARCIS (Netherlands)

    van Erven, L.; van Leeuwen, T. G.; Post, M. J.; van der Veen, M. J.; Velema, E.; Borst, C.

    1992-01-01

    Pulsed mid-infrared lasers are an alternative to excimer lasers for transluminal angioplasty. The mid-infrared lasers, however, were reported to produce "acoustic" wall damage that might impair the immediate and long-term results. To study the immediate and long-term effects on the arterial wall,

  5. Variation of contrast sensitivity after femtosecond laser in situ keratomileusis in changes environments

    Directory of Open Access Journals (Sweden)

    Jing Zhou

    2015-01-01

    Full Text Available AIM: To evaluate the difference of contrast sensitivity(CSin photopic and scotopic environments in eyes with myopia and myopic astigmatism operated with femtosecond laser in situ keratomileusis(femto-LASIKand laser in situ keratomileusis(LASIK.METHODS: In a prospective study 160 myopia and myopic astigmatism patients' eyes were involved, which accepted femto-LASIK or LASIK in our hospital from January 2010 to February 2012. The myopia degree was -1.50~-10.00D, the astigmatism degree ≤-6.0D. Eighty eyes were treated with femto-LASIK in group A, and 80 eyes were treated with LASIK in group B, All patients in the treatment group completed the final 6mo of follow-up. The uncorrected visual acuity(UCVAand the best spectacle-corrected visual acuity(BSCVA, objective and manifest refractions, results of slit-lamp examination, the side effects, intraocular pressure, corneal topography, CS in photopic and scotopic environments were noted.RESULTS: All of operations on 160 cases were successful without severe complication after 6 mo follow-up. CS of femto-LASIK group(group Aat each spatial frequency environment were higher than that of LASIK group(group B. In group A, after 1mo the photopic CS, after 3mo of scotopic CS recovered to the preoperative level, 6mo after surgery improved than before the operation. In group B, after 3mo photopic CS to the preoperative level, scotopic CS at 6mo after operation was still not recovered to the preoperative level.CONCLUSION:Femto-LASIK for correction of myopia and myopic astigmatism, in improving the postoperative contrast sensitivity under shade environment has more advantages than LASIK.

  6. Laser cladding of in situ TiB2/Fe composite coating on steel

    International Nuclear Information System (INIS)

    Du Baoshuai; Zou Zengda; Wang Xinhong; Qu Shiyao

    2008-01-01

    To enhance the wear resistance of mechanical components, laser cladding has been applied to deposit in situ TiB 2 /Fe composite coating on steel using ferrotitanium and ferroboron as the coating precursor. The phase constituents and microstructure of the composite coating were investigated using X-ray diffraction (XRD), scanning electron micrograph (SEM) and electron probe microanalysis (EPMA). Microhardness tester and block-on-ring wear tester were employed to measure the microhardness and dry-sliding wear resistance of the composite coating. Results show that defect-free composite coating with metallurgical joint to the steel substrate can be obtained. Phases presented in the coating consist of TiB 2 and α-Fe. TiB 2 particles which are formed in situ via nucleation-growth mechanism are distributed uniformly in the α-Fe matrix with blocky morphology. The microhardness and wear properties of the composite coating improved significantly in comparison to the as-received steel substrate due to the presence of the hard reinforcement TiB 2

  7. Dry Eye Post-Laser-Assisted In Situ Keratomileusis: Major Review and Latest Updates

    Science.gov (United States)

    Spierer, Oriel

    2018-01-01

    Dry eye is one of the most common complications occurring after laser-assisted in situ keratomileusis (LASIK), with virtually all patients experiencing some degree of postoperative dry eye symptoms. Enhanced understanding of the pathophysiology and mechanism of dry eye development in addition to preoperative screening of patients who are prone to dry eye is essential for better patient satisfaction and for improving short-term visual outcome postoperatively. This article reviews the latest studies published on LASIK-associated dry eye, including epidemiology, pathophysiology, risk factors, preoperative assessment, and management. PMID:29619255

  8. Singlet Fission via an Excimer-Like Intermediate in 3,6-Bis(thiophen-2-yl)diketopyrrolopyrrole Derivatives.

    Science.gov (United States)

    Mauck, Catherine M; Hartnett, Patrick E; Margulies, Eric A; Ma, Lin; Miller, Claire E; Schatz, George C; Marks, Tobin J; Wasielewski, Michael R

    2016-09-14

    Singlet fission (SF) in polycrystalline thin films of four 3,6-bis(thiophen-2-yl)diketopyrrolopyrrole (TDPP) chromophores with methyl (Me), n-hexyl (C6), triethylene glycol (TEG), and 2-ethylhexyl (EH) substituents at the 2,5-positions is found to involve an intermediate excimer-like state. The four different substituents yield four distinct intermolecular packing geometries, resulting in variable intermolecular charge transfer (CT) interactions in the solid. SF from the excimer state of Me, C6, TEG, and EH takes place in τSF = 22, 336, 195, and 1200 ps, respectively, to give triplet yields of 200%, 110%, 110%, and 70%, respectively. The transient spectra of the excimer-like state and its energetic proximity to the lowest excited singlet state in these derivatives suggests that this state may be the multiexciton (1)(T1T1) state that precedes formation of the uncorrelated triplet excitons. The excimer decay rates correlate well with the SF efficiencies and the degree of intermolecular donor-acceptor interactions resulting from π-stacking of the thiophene donor of one molecule with the DPP core acceptor in another molecule as observed in the crystal structures. Such interactions are found to also increase with the SF coupling energies, as calculated for each derivative. These structural and spectroscopic studies afford a better understanding of the electronic interactions that enhance SF in chromophores having strong intra- and intermolecular CT character.

  9. The Laser Ablation Ion Funnel: Sampling for in situ Mass Spectrometry on Mars

    Science.gov (United States)

    Johnson, Paul V.; Hodyss, Robert; Tang, Keqi; Brinckerhoff, William B.; Smith, Richard D.

    2011-01-01

    A considerable investment has been made by NASA and other space agencies to develop instrumentation suitable for in situ analytical investigation of extra terrestrial bodies including various mass spectrometers (time-of-flight, quadrupole ion trap, quadrupole mass filters, etc.). However, the front-end sample handling that is needed to collect and prepare samples for interrogation by such instrumentation remains underdeveloped. Here we describe a novel approach tailored to the exploration of Mars where ions are created in the ambient atmosphere via laser ablation and then efficiently transported into a mass spectrometer for in situ analysis using an electrodynamic ion funnel. This concept would enable elemental and isotopic analysis of geological samples with the analysis of desorbed organic material a possibility as well. Such an instrument would be suitable for inclusion on all potential missions currently being considered such as the Mid-Range Rover, the Astrobiology Field Laboratory, and Mars Sample Return (i.e., as a sample pre-selection triage instrument), among others.

  10. A 3 ps synchronised multi-frame photographic diagnostic for target experiments with the iodine laser

    International Nuclear Information System (INIS)

    Maaswinkel, A.G.M.; Sigel, R.; Baumhacker, H.; Brederlow, G.

    1982-10-01

    A laser system is described with which we obtain a sequence of 6 pictures (interferograms or shadowgrams) of the plasma produced by the iodine laser on solid targets. The system consists of a synchronously pumped dye laser amplified in dye cells pumped by an excimer laser. It delivers a pulse with an energy of 400 μJ and a length of 3 ps at a wavelength of 580 nm that is highly synchronous with the iodine pulse. (orig.)

  11. A new project, SPIRALE. Balloon-borne in situ multi-component measurement using infrared diode lasers

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, G.; Pirre, M.; Robert, C. [Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France); Rosier, B.; Louvet, Y.; Ramaroson, R. [Office National d`Etudes et de Recherches Aerospatiales, 91 - Palaiseau (France); Peyret, C.C. [Universite Pierre et Marie Curie, 75 - Paris (France); Macleod, Y. [Universite Pierreet Marie Curie, 75 - Paris (France); Courtois, D. [Reims Univ., 51 (France). Faculte des Sciences

    1997-12-31

    The scientific goals and the description of a new experiment for stratospheric studies SPIRALE are presented which is a balloon-borne instrument, able to measure in situ several air components (up to 10). Infrared diode laser spectroscopy is applied for monitoring simultaneously atmospheric trace gases at high rate. Its specificity, sensitivity, and wide range of compounds to which it can be applied is described. (R.P.) 5 refs.

  12. A new project, SPIRALE. Balloon-borne in situ multi-component measurement using infrared diode lasers

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, G; Pirre, M; Robert, C [Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France); Rosier, B; Louvet, Y; Ramaroson, R [Office National d` Etudes et de Recherches Aerospatiales, 91 - Palaiseau (France); Peyret, C C [Universite Pierre et Marie Curie, 75 - Paris (France); Macleod, Y [Universite Pierreet Marie Curie, 75 - Paris (France); Courtois, D [Reims Univ., 51 (France). Faculte des Sciences

    1998-12-31

    The scientific goals and the description of a new experiment for stratospheric studies SPIRALE are presented which is a balloon-borne instrument, able to measure in situ several air components (up to 10). Infrared diode laser spectroscopy is applied for monitoring simultaneously atmospheric trace gases at high rate. Its specificity, sensitivity, and wide range of compounds to which it can be applied is described. (R.P.) 5 refs.

  13. Effects of topical vitamin E on keratocyte apoptosis after traditional photorefractive keratectomy.

    Science.gov (United States)

    Bilgihan, K; Adiguzel, U; Sezer, C; Akyol, G; Hasanreisoglu, B

    2001-01-01

    To evaluate the keratocyte apoptosis and effects of topical vitamin E on keratocyte apoptosis after photorefractive surgery. Rabbits were divided into 7 groups, and all groups were compared with controls after epithelial scraping, epithelial scrape and photorefractive keratectomy (PRK) (traditional PRK), transepithelial PRK, production of a corneal flap with microkeratome and laser-assisted in situ keratomileusis (LASIK). The effects of topical Vitamin E treatment were investigated in the traditional PRK group. The terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling assay (to detect DNA fragmentation in situ) and light microscopy have been used to detect apoptosis in rabbit cornea. Transepithelial PRK induced minimal keratocyte apoptosis, less than in all other refractive surgical procedures. The greatest amount of keratocyte apoptosis was observed after traditional PRK (p = 0.001), therefore we tested the effects of topical vitamin E in this group. The number of apoptotic keratocytes significantly reduced after vitamin E therapy (p < 0.005). Keratocytes undergo apoptosis after refractive surgery in response to mechanical epithelial removal, preparing of corneal flap and excimer laser stromal photoablation. The topical application of vitamin E immediately after surgery can prevent keratocyte apoptosis, and this result suggests that free radicals may be partly responsible for keratocyte apoptosis after excimer laser keratectomy. Copyright 2001 S. Karger AG, Basel

  14. Laser technologies for laser accelerators. Annual report

    International Nuclear Information System (INIS)

    1985-01-01

    The primary result of the work reported is the determination of laser system architectures that satsify the requirements of high luminosity, high energy (about 1 TeV), electron accelerators. It has been found that high laser efficiency is a very hard driver for these accelerators as the total average laser output optical power is likely to fall above 10 MW. The luminosity requires rep rates in the kHz range, and individual pulse lengths in the 1-10 psec range are required to satisfy acceleration gradient goals. CO 2 and KrF lasers were chosen for study because of their potential to simultaneously satisfy the given requirements. Accelerator luminosity is reviewed, and requirements on laser system average power and rep rate are determined as a function of electron beam bunch parameters. Laser technologies are reviewed, including CO 2 , excimers, solid state, and free electron lasers. The proposed accelerator mechanisms are summarized briefly. Work on optical transport geometries for near and far field accelerators are presented. Possible exploitation of the CO 2 and DrF laser technology to generate the required pulse lengths, rep rates, and projected efficiencies is illustrated and needed development work is suggested. Initial efforts at developing a 50 GeV benchmark conceptual design and a 100 MeV demonstration experiment conceptual design are presented

  15. Simulation of pulsed dielectric barrier discharge xenon excimer lamp

    International Nuclear Information System (INIS)

    Bogdanov, E A; Kudryavtsev, A A; Arslanbekov, R R; Kolobov, V I

    2004-01-01

    Recently, it has been shown that the efficiency of excimer lamps can be drastically increased in a pulsed regime. A one-dimensional simulation of pulsed excimer lamps has been performed by Carman and Mildren (2003 J. Phys. D: Appl. Phys. 36 19) (C and M). However, some computational results of the work of C and M are questionable and need to be revisited. In this paper, a dielectric barrier discharge (DBD) in xenon has been simulated for operating conditions similar to those of C and M to better understand plasma dynamics in a pulsed regime. Our simulation results differ considerably from the computational results of C and M. Although these differences do not affect profoundly the plasma macro parameters measured in the C and M experiments, they offer a better understanding of plasma dynamics in pulsed DBDs and form a solid foundation for computational optimization of excimer lamps. It was found that the dynamics of breakdown and the current pulse depend significantly on the initial densities of species after a previous pulse, and so it is important to accurately simulate the plasma evolution in both the afterglow and active stages. It seems possible to modify the power deposition in the plasma by varying external discharge parameters such as the amplitude and the rise time of the applied voltage, and to modify the plasma composition by changing the pulse repetition rate and plasma decay in the afterglow stage

  16. 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.

  17. In Situ Carbon Isotope Analysis by Laser Ablation MC-ICP-MS.

    Science.gov (United States)

    Chen, Wei; Lu, Jue; Jiang, Shao-Yong; Zhao, Kui-Dong; Duan, Deng-Fei

    2017-12-19

    Carbon isotopes have been widely used in tracing a wide variety of geological and environmental processes. The carbon isotope composition of bulk rocks and minerals was conventionally analyzed by isotope ratio mass spectrometry (IRMS), and, more recently, secondary ionization mass spectrometry (SIMS) has been widely used to determine carbon isotope composition of carbon-bearing solid materials with good spatial resolution. Here, we present a new method that couples a RESOlution S155 193 nm laser ablation system with a Nu Plasma II MC-ICP-MS, with the aim of measuring carbon isotopes in situ in carbonate minerals (i.e., calcite and aragonite). Under routine operating conditions for δ 13 C analysis, instrumental bias generally drifts by 0.8‰-2.0‰ in a typical analytical session of 2-3 h. Using a magmatic calcite as the standard, the carbon isotopic composition was determined for a suite of calcite samples with δ 13 C values in the range of -6.94‰ to 1.48‰. The obtained δ 13 C data are comparable to IRMS values. The combined standard uncertainty for magmatic calcite is ICP-MS can serve as an appropriate method to analyze carbon isotopes of carbonate minerals in situ.

  18. Nuclear-driven flashlamp pumping of the atomic iodine laser

    International Nuclear Information System (INIS)

    Miley, G.H.

    1992-03-01

    This report is a study of the atomic iodine laser pumped with nuclear- excited XeBr fluorescence. Preliminary experiments, conducted in the TRIGA reactor investigated the fluorescence of the excimer XeBr under nuclear pumping with 10 B and 3 He, for use as a flashlamp gas to stimulate the laser. These measurements included a determination of the fluorescence efficiency (light emitted in the wavelength region of interest, divided by energy deposited in the gas) of XeBr under nuclear pumping, with varying excimer mixtures. Maximum fluorescence efficiencies were approximately 1%. In order to better understand XeBr under nuclear excitation, a kinetics model of the system was prepared. The model generated the time-dependant concentrations of 20 reaction species for three pulse sizes, a TRIGA pulse, a fast burst reactor pulse, and an e-beam pulse. The modeling results predicted fluorescence efficiencies significantly higher (peak efficiencies of approximately 10%) than recorded in the fluorescence experiments. The cause of this discrepancy was not fully determined. A ray tracing computer model was also prepared to evaluate the efficiency with which nuclear-induced fluorescence generated in one cavity of a laser could be coupled into another cavity containing an iodine lasant. Finally, an experimental laser cell was constructed to verify that nuclear-induced XeBr fluorescence could be used to stimulate a laser. Lasing was achieved at 1.31 micron in the TRIGA using C 3 F 7 I, a common iodine lasant. Peak laser powers were approximately 20 mW. Measured flashlamp pump powers at threshold agreed well with literature values, as did lasant pressure dependency on laser operation

  19. Development of a laser-based heating system for in situ synchrotron-based X-ray tomographic microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fife, Julie L., E-mail: julie.fife@psi.ch [Laboratory for Synchrotron Radiation, Swiss Light Source, Paul Scherrer Institut, Villigen (Switzerland); Computational Materials Laboratory, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Rappaz, Michel [Computational Materials Laboratory, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Pistone, Mattia [Institute for Geochemistry and Petrology, Swiss Federal Institute of Technology of Zurich, Zurich (Switzerland); Celcer, Tine [Laboratory for Synchrotron Radiation, Swiss Light Source, Paul Scherrer Institut, Villigen (Switzerland); The Centre of Excellence for Biosensors, Instrumentation and Process Control, Solkan (Slovenia); Mikuljan, Gordan [Laboratory for Synchrotron Radiation, Swiss Light Source, Paul Scherrer Institut, Villigen (Switzerland); Stampanoni, Marco [Laboratory for Synchrotron Radiation, Swiss Light Source, Paul Scherrer Institut, Villigen (Switzerland); Institute for Biomedical Engineering, Swiss Federal Institute of Technology and University of Zurich, Zurich (Switzerland)

    2012-05-01

    A laser-based heating system has been developed at the TOMCAT beamline of the Swiss Light Source for in situ observations of moderate-to-high-temperature applications of materials. Understanding the formation of materials at elevated temperatures is critical for determining their final properties. Synchrotron-based X-ray tomographic microscopy is an ideal technique for studying such processes because high spatial and temporal resolutions are easily achieved and the technique is non-destructive, meaning additional analyses can take place after data collection. To exploit the state-of-the-art capabilities at the tomographic microscopy and coherent radiology experiments (TOMCAT) beamline of the Swiss Light Source, a general-use moderate-to-high-temperature furnace has been developed. Powered by two diode lasers, it provides controlled localized heating, from 673 to 1973 K, to examine many materials systems and their dynamics in real time. The system can also be operated in various thermal modalities. For example, near-isothermal conditions at a given sample location can be achieved with a prescribed time-dependent temperature. This mode is typically used to study isothermal phase transformations; for example, the formation of equiaxed grains in metallic systems or to nucleate and grow bubble foams in silicate melts under conditions that simulate volcanic processes. In another mode, the power of the laser can be fixed and the specimen moved at a constant speed in a user-defined thermal gradient. This is similar to Bridgman solidification, where the thermal gradient and cooling rate control the microstructure formation. This paper details the experimental set-up and provides multiple proofs-of-concept that illustrate the versatility of using this laser-based heating system to explore, in situ, many elevated-temperature phenomena in a variety of materials.

  20. Robotic Laser Coating Removal System

    Science.gov (United States)

    2008-07-01

    using a transverse excitation at atmospheric pressure (TEA) method. o Excimer lasers use reactive gases, such as chlorine and fluorine , mixed with... Varnish , and Related Products on Test Panels.   All topcoats were applied over the primer within the manufacturer’s recommended time and  artificially aged