期刊文献+
共找到92,157篇文章
< 1 2 250 >
每页显示 20 50 100
Stroke gets in your eyes:stroke-induced retinal ischemia and the potential of stem cell therapy 预览
1
作者 Chase Kingsbury Matt Heyck +2 位作者 Brooke Bonsack Jea-Young Lee Cesar V.Borlongan 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第6期1014-1018,共5页
Stroke persists as a global health and economic crisis,yet only two interventions to reduce stroke-induced brain injury exist.In the clinic,many patients who experience an ischemic stroke often further suffer from ret... Stroke persists as a global health and economic crisis,yet only two interventions to reduce stroke-induced brain injury exist.In the clinic,many patients who experience an ischemic stroke often further suffer from retinal ischemia,which can inhibit their ability to make a functional recovery and may diminish their overall quality of life.Despite this,no treatments for retinal ischemia have been developed.In both cases,ischemia-induced mitochondrial dysfunction initiates a cell loss cascade and inhibits endogenous brain repair.Stem cells have the ability to transfer healthy and functional mitochondria not only ischemic neurons,but also to similarly endangered retinal cells,replacing their defective mitochondria and thereby reducing cell death.In this review,we encapsulate and assess the relationship between cerebral and retinal ischemia,recent preclinical advancements made using in vitro and in vivo retinal ischemia models,the role of mitochondrial dysfunction in retinal ischemia pathology,and the therapeutic potential of stem cell-mediated mitochondrial transfer.Furthermore,we discuss the pitfalls in classic rodent functional assessments and the potential advantages of laser Doppler as a metric of stroke progression.The studies evaluated in this review highlight stem cell-derived mitochondrial transfer as a novel therapeutic approach to both retinal ischemia and stroke.Furthermore,we posit the immense correlation between cerebral and retinal ischemia as an underserved area of study,warranting exploration with the aim of these treating injuries together. 展开更多
关键词 laser Doppler MCAO mesenchymal stem cells mitochondrial network mitochondrial transfer ophthalmic artery optic nerve oxygen-glucose deprivation regenerative medicine retinal ganglion cells visual impairment
在线阅读 下载PDF
Effects of Q-Switched Laser Treatments on Acquired Bilateral Nevus of Ota-Like Macules:A Retrospective Comparative Study
2
作者 Rong Zeng Yu-Zhen Liu +7 位作者 Tong Lin Li-Fang Guo Yi-Ping Ge Meng-Li Zhang Yin Yang Qiu-Ju Wu Yu-Le Wu Min Li 《国际皮肤性病学杂志(英文)》 2019年第2期70-76,共7页
Objective:Q-switched lasers,including 1064-nm Nd:YAG nansecond laser (QSNYL),755-nm alexandrite nanosecond laser (QSAL),and 694-nm nanosecond ruby laser (QSRL),are clinically available for the treatment of acquired bi... Objective:Q-switched lasers,including 1064-nm Nd:YAG nansecond laser (QSNYL),755-nm alexandrite nanosecond laser (QSAL),and 694-nm nanosecond ruby laser (QSRL),are clinically available for the treatment of acquired bilateral nevus of Ota-like macules (ABNOM).However,no reliable evidence from large-scale comparative studies identifies which type of laser works best.This study aims to determine the differences in the effectiveness,complications,and risk factors of QSNYL,QSAL,and QSRL in the treatment of ABNOM,further to provide evidence for clinician to make optimal choice according to the condition of patients.Methods:We collected the data from 685 ABNOM patients,including clinical features,medical treatments,and follow-up,since 1999 to 2014.The Kruskal-Wallis test was used to compare therapeutic differences between the three groups.The risk factors were analyzed using univariate analysis (x2 test) and multivariate logistic regression analysis.Results:The overall treatment efficiency of the QSNYL group (52.5%) and QSAL group (51.9%) was higher than that of the QSRL group (39.5%) (x2 =17.468,P < 0.001).The onset time of the QSRL and QSAL groups was shorter than that of the QSNYL group.The factors influencing efficacy in the QSNYL group were age at first treatment,number of treatments,coexistence with melesma,and the presence of hyperpigmentation;in the QSAL group was the number of treatments;and in the QSRL group was the number of treatments and hyperpigmentation.The prevalence of hyperpigrnentation in the QSNYL group (30.5%) and the QSAL group (27.5%) was lower than that of the QSRL group (47.3%) (X2=6.576,P<0.001).Concluslon:The QSNYL,QSAL,and QSRL are all effective and safe treatments for ABNOM.Considering the overall efficacy,duration of treatment,side effects,and risk factors,the QSAL is an optimal choice for ABNOM treatment. 展开更多
关键词 ACQUIRED BILATERAL nevus of Ota-like macules Q-switched LASER Nd∶YAG LASER ALEXANDRITE LASER ruby LASER RETROSPECTIVE comparative study
A shortcut to marking 3D target curves on curved surface via a galvanometric laser scanner
3
作者 Junchao TU Mingang WANG Liyan ZHANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第6期1555-1563,共9页
Marking arbitrary three-dimensional(3D) target curves on given objects with curved surface is required in many industrial fields, such as fabric prepreg placement in composite material part fabrication, product assemb... Marking arbitrary three-dimensional(3D) target curves on given objects with curved surface is required in many industrial fields, such as fabric prepreg placement in composite material part fabrication, product assembly, surface painting for decoration, etc. A shortcut to the solution of this intractable problem is proposed by utilizing a galvanometric laser scanner(GLS) with the aid of a camera. Without using the existing tedious GLS calibration procedures,the proposed method directly establishes a mapping between the 3D coordinates of the laser spots on the object surface and the control voltages of the scanner. A single-hidden layer feedforward neural network(SLFN) is employed to model the mapping. By projecting a dense grid of laser spots on the object to be marked and simultaneously taking only one image, the SLFN model is trained in minutes via a linear solving mechanism. Experiments demonstrate that the trained SLFN model has a good generalization performance for marking 3D target curves. The 3D laser marking errors on experimental objects are less than 0.5 mm. The proposed method is especially suitable for on-site use and can be conveniently extended to multiple GLSs for marking large complex objects. 展开更多
关键词 Calibration FABRIC PREPREG PLACEMENT LASER materials processing LASER SCANNER Three-dimensional LASER MARKING
基于光纤激光放大倍频的冷原子钟光源
4
作者 王新文 项静峰 +3 位作者 彭向凯 刘亢亢 刘亮 吕德胜 《光学学报》 EI CAS CSCD 北大核心 2019年第9期229-235,共7页
用于激光冷却与原子布居数探测的激光光源是冷原子钟的重要组成部分,选用工业技术成熟的1560 nm光纤激光器和光纤放大器分别作为种子源和光放大器,经非线性倍频晶体对放大后的激光进行倍频,得到较大功率的780 nm的激光,通过饱和吸收稳... 用于激光冷却与原子布居数探测的激光光源是冷原子钟的重要组成部分,选用工业技术成熟的1560 nm光纤激光器和光纤放大器分别作为种子源和光放大器,经非线性倍频晶体对放大后的激光进行倍频,得到较大功率的780 nm的激光,通过饱和吸收稳频得到冷却激光,一部分冷却激光利用电光调制器和声光调制器移频6.8 GHz得到重泵浦激光,对上述激光进行适当的功率分配后提供给冷原子钟。对该套激光装置关键器件进行了特性测试,将稳频后的倍频激光与锁定在超稳激光上的光学频率梳进行拍频,得到的激光的线宽在74 kHz左右,其短期稳定度比外腔半导体激光器提高半个多数量级。将这样的激光光源应用于冷原子钟,可以减小探测激光频率噪声对喷泉钟稳定度的限制。 展开更多
关键词 激光器 冷原子钟 光纤激光器 激光倍频 频率稳定度
Hierarchical microstructures with high spatial frequency laser induced periodic surface structures possessing different orientations created by femtosecond laser ablation of silicon in liquids 预览
5
作者 Dongshi Zhang Koji Sugioka 《光电进展(英文)》 2019年第3期1-18,共18页
High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or micro... High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or microgrooves at relatively higher fluences above 1 J/cm^2.This work aims to enrich the variety of HSFLs-containing hierarchical microstructures,by femtosecond laser(pulse duration:457 fs,wavelength:1045 nm,and repetition rate:100 kHz)in liquids(water and acetone)at laser fluence of 1.7 J/cm^2.The period of Si-HSFLs in the range of 110–200 nm is independent of the scanning speeds(0.1,0.5,1 and 2 mm/s),line intervals(5,15 and 20μm)of scanning lines and scanning directions(perpendicular or parallel to light polarization direction).It is interestingly found that besides normal HSFLs whose orientations are perpendicular to the direction of light polarization,both clockwise or anticlockwise randomly tilted HSFLs with a maximal deviation angle of 50°as compared to those of normal HSFLSs are found on the microstructures with height gradients.Raman spectra and SEM characterization jointly clarify that surface melting and nanocapillary waves play important roles in the formation of Si-HSFLs.The fact that no HSFLs are produced by laser ablation in air indicates that moderate melting facilitated with ultrafast liquid cooling is beneficial for the formation of HSFLs by LALs.On the basis of our findings and previous reports,a synergistic formation mechanism for HSFLs at high fluence was proposed and discussed,including thermal melting with the concomitance of ultrafast cooling in liquids,transformation of the molten layers into ripples and nanotips by surface plasmon polaritons(SPP)and second-harmonic generation(SHG),and modulation of Si-HSFLs direction by both nanocapillary waves and the localized electric field coming from the excited large Si particles. 展开更多
关键词 HIGH spatial frequency LASER induced periodic SURFACE structures SILICON LASER ablation in liquids HIERARCHICAL MICROSTRUCTURES femtosecond LASER HIGH fluence formation mechanism SURFACE melting nanocapillary wave SURFACE plasmon polaritons second-harmonic generation
在线阅读 下载PDF
High-power,Joule-class,temporally shaped multi-pass ring laser amplifier with two Nd:glass laser heads
6
作者 Jiangtao Guo Jiangfeng Wang +5 位作者 Hui Wei Wenfa Huang Tingrui Huang Gang Xia Wei Fan Zunqi Lin 《高功率激光科学与工程:英文版》 CAS CSCD 2019年第1期60-67,共8页
A high-power.Joule-class,nanosecond temporally shaped multi-pass ring laser amplifier system with two neodymiumdoped phosphate glass(Nd:glass)laser heads is demonstrated.The laser amplifier system consists of three pa... A high-power.Joule-class,nanosecond temporally shaped multi-pass ring laser amplifier system with two neodymiumdoped phosphate glass(Nd:glass)laser heads is demonstrated.The laser amplifier system consists of three parts:an all-fiber structure seeder,a diode-pumped Nd:glass regenerative amplifier and a multi-pass ring amplifier,where the thermally induced depolarization of two laser heads is studied experimentally and theoretically.Following the injection of a square pulse with the pulse energy of 0.9 mJ and pulse width of 6 ns,a 0.969-J high-energy laser pulse at 1 Hz was generated,which had the ability to change the waveform arbitrarily,based on the all-fiber structure front end.The experimental results show that the proposed laser system is promising to be adopted in the preamplifier of high-power laser facilities. 展开更多
关键词 DEPOLARIZATION compensation LASER AMPLIFIER NEODYMIUM LASER ring LASER
High-brightness all-fiber Raman lasers directly pumped by multimode laser diodes
7
作者 S.A.Babin 《高功率激光科学与工程:英文版》 CAS CSCD 2019年第1期107-113,共7页
High-brightness fiber laser sources usually utilize active rare-earth-doped fibers cladding-pumped by multimode laser diodes(LDs),but they operate in limited wavelength ranges.Singlemode-passive-fiber based Raman lase... High-brightness fiber laser sources usually utilize active rare-earth-doped fibers cladding-pumped by multimode laser diodes(LDs),but they operate in limited wavelength ranges.Singlemode-passive-fiber based Raman lasers are able to operate at almost any wavelength being pumped by high-power fiber lasers.One of the interesting possibilities is to directly pump graded-index(GRIN)multimode passive fibers by available high-power multimode LDs at 915-940 nm,thus achieving high-power Raman lasing in the wavelength range of 950-1000 nm,which is problematic for rare-earthdoped fiber lasers.Here we review the latest results on the development of all-fiber high-brightness LD-pumped sources based on GRIN fiber with in-fiber Bragg gratings(FBGs).The mode-selection properties of FBGs inscribed by fs pulses supported by the Raman clean-up effect result in efficient conversion of multimode pump into a high-quality output beam at 9xx nm.GRIN fibers with core diameters 62.5,85 and 100μm are compared.Further scaling capabilities and potential applications of such sources are discussed. 展开更多
关键词 beam cleaning fiber LASER high BRIGHTNESS LASER diode pumping Raman LASER
固体自拉曼激光器多波长输出研究 预览
8
作者 伍锡山 张鹏 +2 位作者 周博睿 刘彬 索文凯 《激光与红外》 CAS CSCD 北大核心 2019年第2期181-186,共6页
实验对比了a切和c切的Nd∶YVO4晶体作为激光晶体时,激光器输出光光谱及输出功率上的区别。设计了一种小型化固体自拉曼多波长激光器,实验证明通过调节倍频晶体BBO的角度,可实现多波长选择性输出及同时输出,并测量了其输出光谱及单波长... 实验对比了a切和c切的Nd∶YVO4晶体作为激光晶体时,激光器输出光光谱及输出功率上的区别。设计了一种小型化固体自拉曼多波长激光器,实验证明通过调节倍频晶体BBO的角度,可实现多波长选择性输出及同时输出,并测量了其输出光谱及单波长输出时的功率。 展开更多
关键词 激光器 拉曼激光器 固体激光器 光谱 多波长
在线阅读 下载PDF
Review on TNSA diagnostics and recent developments at SPARC LAB
9
作者 Fabrizio Bisesto Mario Galletti +5 位作者 Maria Pia Anania Massimo Ferrari Riccardo Pompili Mordechai Botton Elad Schleifer Arie Zigler 《高功率激光科学与工程:英文版》 CAS CSCD 2019年第3期228-239,共12页
Interaction between high-intensity lasers with solid targets is the key process in a wide range of novel laser-based particle accelerator schemes,as well as electromagnetic radiation sources.Common to all the processe... Interaction between high-intensity lasers with solid targets is the key process in a wide range of novel laser-based particle accelerator schemes,as well as electromagnetic radiation sources.Common to all the processes is the generation of femtosecond pulses of relativistic electrons emitted from the targets as forerunners of the later-time principal products of the interaction scheme.In this paper,some diagnostics employed in laser–solid matter interaction experiments related to electrons,protons,ions,electromagnetic pulses(EMPs)and X-rays are reviewed.Then,we present our experimental study regarding fast electrons and EMPs utilizing a femtosecond-resolution detector previously adopted only in accelerator facilities. 展开更多
关键词 high power laser laser-plasma interaction pulsed electric field diagnostic ultra-short high-intensity laser pulses
Tailoring metallic surface properties induced by laser surface processing for industrial applications 预览
10
作者 Guoqing Hu Yang Song Yingchun Guan 《纳米技术与精密工程(英文)》 CAS CSCD 2019年第1期29-34,共6页
As a simple,reproducible,and pollution-free technique with the potential of integration and automation,laser processing has attracted increasing attention.Laser processing,which includes laser polishing,laser cleaning... As a simple,reproducible,and pollution-free technique with the potential of integration and automation,laser processing has attracted increasing attention.Laser processing,which includes laser polishing,laser cleaning,and fabrication of laser-induced micro-/nano-structures,has been demonstrated to yield smooth,clean,functional surfaces and effective joining.Laser polishing is an advanced,highly efficient,and ecofriendly polishing technology.This study demonstrated the laser polishing of a selective laser-melted Inconel 718(IN718)superalloy and a titaniumalloy sample.The surface roughnesses Ra and Rz of the IN718 superalloy were respectively reduced from 8 and 33μm to 0.2 and 0.8μm,and the Ra of the titanium alloy was reduced from 9.8μm to 0.2μm.Moreover,the wear resistance and corrosion resistance of the IN718 were apparently improved.As another surface-related processingmethod,laser cleaningwas used to clean terminal blocks.Almost all the contaminants were removed,as verified by the absence of their chemical compositions and the decreased surface roughness.In addition,a superhydrophobic surface with a contact angle of over 160°and sliding angle of b8°on stainless steel was obtained by laser texturing treatment.These results demonstrate the high potential of laser processing in the scientific,technological,and industrial fields. 展开更多
关键词 LASER PROCESSING LASER POLISHING LASER CLEANING SUPERHYDROPHOBICITY
在线阅读 下载PDF
100 Hz重复频率脉冲中红外HF化学激光器
11
作者 黄超 黄珂 +3 位作者 易爱平 朱峰 马连英 安晓霞 《中国激光》 EI CAS CSCD 北大核心 2019年第2期17-22,共6页
基于自动紫外预电离的放电引发方式,研制出紧凑型闭环高重复频率非链式HF化学激光器。该激光器采用非对称电极结构,放电腔室的尺寸为12 mm×17 mm×460 mm。为了实现重复频率运行过程中放电区气体的快速置换,循环气体垂直于光... 基于自动紫外预电离的放电引发方式,研制出紧凑型闭环高重复频率非链式HF化学激光器。该激光器采用非对称电极结构,放电腔室的尺寸为12 mm×17 mm×460 mm。为了实现重复频率运行过程中放电区气体的快速置换,循环气体垂直于光轴流过放电区,气体流速约为9 m/s。当总气压为14 kPa时,在摩尔分数分别为92%和8%的SF6和C2H6混合气体中,100 Hz重复频率脉冲HF激光器的输出功率为50 W。 展开更多
关键词 激光器 中红外激光 HF化学激光器 放电引发 紫外预电离
无热二极管泵浦Nd:YAG激光器的发展
12
作者 金锋 吴振宇 衣学斌 《激光杂志》 北大核心 2019年第1期18-21,共4页
综述了无热二极管泵浦Nd:YAG激光器技术的发展,无热激光器是最新一代可在宽温度范围内正常工作的免温控全固态激光器,其减小了体积、重量、能耗,且即开即用,可用于人眼安全激光测距机、激光目标指示器、激光测距/目标指示器等军用领域。
关键词 激光器 二极管泵浦固体激光器 二极管泵浦无热激光器
High power diode-pumped passively mode-locked Nd:YVO4 laser at repetition rate of 3.2 GHz
13
作者 程梦尧 王兆华 +4 位作者 曹艳芳 孟祥昊 朱江峰 王军利 魏志义 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期122-125,共4页
A compact high power diode-pumped passively mode-locked Nd:YVO4 laser with high repetition rate is realized.Using an Nd:YVO4 crystal and a semiconductor saturable absorber mirror (SESAM) in the oscillator,the picoseco... A compact high power diode-pumped passively mode-locked Nd:YVO4 laser with high repetition rate is realized.Using an Nd:YVO4 crystal and a semiconductor saturable absorber mirror (SESAM) in the oscillator,the picosecond pulse output with an average power of 1.38 W,a repetition rate of 3.24 GHz,and a pulse duration of 11.4 ps is achieved.After one stage of amplification,the final output power reaches 11.34 W,corresponding to a total optical-to-optical efficiency of about 32%.The root mean square (RMS) value of power fluctuation is demonstrated to be less than 0.6% in 24 hours,showing a superior stability with the compact configuration. 展开更多
关键词 ALL-SOLID-STATE LASER high REPETITION rate Nd:YVO4 LASER MODE-LOCKED LASER
Control of wall thickness and surface morphology of tungsten thin wall parts by adjusting selective laser melting parameters
14
作者 Yan-jun Xie Huai-chao Yang +3 位作者 Xue-bing Wang Lin Zhao Chun-jiang Kuang Wei Han 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第2期182-190,共9页
The tungsten thin wall parts which were used as high-performance collimator devices were fabricated by optimizing selective laser melting laser parameters.The effect of laser power and scan rate on wall thickness and ... The tungsten thin wall parts which were used as high-performance collimator devices were fabricated by optimizing selective laser melting laser parameters.The effect of laser power and scan rate on wall thickness and surface morphology of tungsten山in wall parts was investigated,respectively.The results indicated that the wall thickness increased with the enhancemem in laser power as a linear relationship.On the contrary,the wall thickness decayed exponentially with the acceleration in laser sean rate.Meanwhile,the wall thickness of the parts fabricated by laser double-pass melting was ihinner than that fabricated by laser single-pass melting.In addition,mathematic models for selecting suitable laser power and laser sean rate to fabricate specified tungsten thin wall parts were proposed.Furthermore,the effects of laser parameters on the top surface roughness,adhesive parts and hot cracks were also discussed. 展开更多
关键词 Selective LASER MELTING TUNGSTEN LASER power SCAN rate THIN wall part Surface morphology
In uence of Particle Size on Laser Absorption and Scanning Track Formation Mechanisms of Pure Tungsten Powder During Selective Laser Melting 预览
15
作者 Jiayao Zhang Dongdong Gu +4 位作者 Ying Yang Hongmei Zhang Hongyu Chen Donghuai Dai Kaijie Lin 《工程(英文)》 2019年第4期736-745,共10页
A three-dimensional laser absorption model based on ray tracing was established to describe the coupled interaction of a laser beam with particles in the powder layers of pure tungsten(W)material processed by selectiv... A three-dimensional laser absorption model based on ray tracing was established to describe the coupled interaction of a laser beam with particles in the powder layers of pure tungsten(W)material processed by selective laser melting(SLM).The influence of particle size on the powder-to-laser absorptivity and underlying absorption behavior was investigated.An intrinsic relationship between the absorption,distribution of absorbed irradiance within the powder layers,and surface morphology and geometric characteristics(e.g.,contact angle,width and height of tracks,and remelted depth)of the laser scanning tracks is presented here.Simulation conclusions indicate that the absorptivity of the powder layers considerably exceeds the single powder particle value or the dense solid material value.With an increase in particle size,the powder layer absorbs less laser energy.The maximum absorptivity of theWpowder layers reached 0.6030 at the particle size of 5 lm.The distribution of laser irradiance on the particle surface was sensitive to particle size,azimuthal angle,and the position of the powder particles on the substrate.The maximum irradiance in the powder layers decreased from 1.117×10^–3 to 0.85×10^–3W·μm^-2 and the contour of the irradiance distribution in the center of the irradiated area gradually contracted when the particle size increased from 5 to 45 lm.An experimental study on the surface morphologies and cross-sectional geometric characteristics of SLM-fabricated W material was performed,and the experimental results validated the mechanisms of the powder-to-laser-absorption behavior that were obtained in simulations.This work provides a scientific basis for the application of the ray-tracing model to predict the wetting and spreading ability of melted tracks during SLM additive manufacturing in order to yield a sound laser processability. 展开更多
关键词 Selective LASER melting(SLM) Tungsten RAY-TRACING model ABSORPTIVITY LASER SCANNING TRACKS
在线阅读 免费下载
Space debris laser ranging with a 60 W single-frequency slab nanosecond green laser at 200 Hz
16
作者 张海峰 龙明亮 +3 位作者 邓华荣 吴志波 程志恩 张忠萍 《中国光学快报:英文版》 SCIE EI CAS CSCD 2019年第5期44-48,共5页
Space debris laser ranging was achieved with a 60 W, 200 Hz, 532 nm nanosecond slab, single-frequency green laser at the Shanghai Astronomical Observatory's 60 cm satellite laser ranging systern. There were 174 pa... Space debris laser ranging was achieved with a 60 W, 200 Hz, 532 nm nanosecond slab, single-frequency green laser at the Shanghai Astronomical Observatory's 60 cm satellite laser ranging systern. There were 174 passes of space debris measured in 2017, with the minimum radar cross section (RCS) being 0.25 m2 and the highest ranging precision up to 13.6 cm. The RCS of space debris measured with the farthest distances in 174 passes was analyzed. The results show that the farthest measurement distance (R) and RCS (S) were fitted to R = 1388.159S024312, indicating that this laser can measure the distance of 1388.159 km at an RCS of 1 m2, which is very helpful to surveillance and research on low-Earth-orbit space debris. 展开更多
关键词 Space debris LASER ranging radar cross section(RCS) 60 W SINGLE-FREQUENCY SLAB nanosecond green LASER
Generation of high energy laser-driven electron and proton sources with the 200 TW system VEGA 2 at the Centro de Laseres Pulsados
17
作者 L.Volpe R.Fedosejevs +23 位作者 G.Gatti J.A.Pérez-Hernández C.Méndez J.Apinaniz X.Vaisseau C.Salgado M.Huault S.Malko G.Zeraouli V.Ospina A.Longman D.De Luis K.Li O.Varela E.García I.Hernandez J.D.Pisonero J.Garcia Ajates J.M.Alvarez C.García M.Rico D.Arana J.Hernandez-Toro L.Roso 《高功率激光科学与工程:英文版》 CAS CSCD 2019年第2期34-39,共6页
The Centro de Laseres Pulsados in Salamanca,Spain has recently started operation phase and the first user access period on the 6 J 30 fs 200 TW system(VEGA 2)already started at the beginning of 2018.In this paper we r... The Centro de Laseres Pulsados in Salamanca,Spain has recently started operation phase and the first user access period on the 6 J 30 fs 200 TW system(VEGA 2)already started at the beginning of 2018.In this paper we report on two commissioning experiments recently performed on the VEGA 2 system in preparation for the user campaign.VEGA 2 system has been tested in different configurations depending on the focusing optics and targets used.One configuration(long focal length F=130 cm)is for underdense laser-matter interaction where VEGA 2 is focused onto a low density gas-jet generating electron beams(via laser wake field acceleration mechanism)with maximum energy up to 500 MeV and an X-ray betatron source with a 10 keV critical energy.A second configuration(short focal length F= 40 cm)is for overdense laser-matter interaction where VEGA 2 is focused onto a 5 μm thick Al target generating a proton beam with a maximum energy of 10 MeV and temperature of 2.5 MeV.In this paper we present preliminary experimental results. 展开更多
关键词 high power laser LASER-PLASMA PARTICLE ACCELERATION
High-peak-power temporally shaped nanosecond fiber laser immune to SPM-induced spectral broadening
18
作者 Rongtao Su Pengfei Ma +5 位作者 Pu Zhou Zilun Chen Xiaolin Wang Yanxing Ma Jian Wu Xiaojun Xu 《高功率激光科学与工程:英文版》 CAS CSCD 2019年第2期51-58,共8页
High-peak-power transform-limited narrow-linewidth nanosecond all-fiber lasers are desired in a range of applications.However,their linewidths will be broadened by self-phase modulation(SPM).We propose a novel concept... High-peak-power transform-limited narrow-linewidth nanosecond all-fiber lasers are desired in a range of applications.However,their linewidths will be broadened by self-phase modulation(SPM).We propose a novel concept that generates transform-limited laser pulses by temporally shaping the pulse seed.The impact of the pulse shape on SPM-induced spectral broadening was studied numerically and experimentally.It was found theoretically that the square-shape pulsed laser is immune to SPM-induced spectral broadening.Based on this principle,we built a high-peak-power,linearly polarized,square-shape nanosecond all-fiber laser in a master oscillator power amplifier(MOPA)configuration.Stimulated Brillouin scattering(SBS)limited peak powers of 4.02 kW,5.06 kW,6.52 kW and 9.30 kW were obtained at pulse widths of 8 ns,7 ns,6 ns and 5 ns.Thanks to the square-shape pulsed seed,the linewidths at maximum peak power remained at 129.5 MHz,137.6 MHz,156.2 MHz and 200.1 MHz,respectively,close to the transform-limited values of110.8 MHz,126.6 MHz,147.7 MHz and 177.3 MHz. 展开更多
关键词 fiber LASER nanosecond pulsed LASER NARROW LINEWIDTH self-phase modulation stimulated BRILLOUIN scattering
The Impact of Subungual Osteochondroma Deformans on Severely Mycotic Toenails 预览
19
作者 Christopher Brian Stewart Maryellen Ann Waltz 《化妆品、皮肤病及应用期刊(英文)》 2019年第1期56-65,共10页
Background: We examined 94 toenails exhibiting clinical signs of severe onychomycosis taking into account multiple contributing factors, not the least of which was Subungual Osteochondroma Deformans (SOD). We hypothes... Background: We examined 94 toenails exhibiting clinical signs of severe onychomycosis taking into account multiple contributing factors, not the least of which was Subungual Osteochondroma Deformans (SOD). We hypothesize that SOD plays a significant role in both the etiology and treatment of onychomycosis. Methods/Results: A retrospective post-treatment outcome analysis was performed comparing two groups of severely mycotic toenails. The first group of 25 fungal nails showed 54.31% improvement following treatment by both surgical nail avulsion and a 1064 YAG laser-based Nail Restoration algorithm. The second group of 69 fungal nails was not only treated using the same nail avulsion/laser-based algorithm but was also evaluated for SOD lesions which were surgically removed when present, resulting in 95.31% improvement. The overall incidence of SOD lesions in the second group of severely mycotic toenails was 73.91%. Conclusion: We submit that at 73.91% Subungual Osteochondroma Deformans has an under-reported and under-appreciated association with toenail fungus. Generally, we find that our success rates in treating severe toenail fungus using our laser-based Nail Restoration Protocols are much higher when SOD lesions are surgically removed. 展开更多
关键词 SUBUNGUAL OSTEOCHONDROMA Deformans ONYCHOMYCOSIS Laser TOENAIL Topical Surgery Bone SPUR
在线阅读 免费下载
Weldability, microstructure and mechanical properties of laser-welded selective laser melted 304 stainless steel joints
20
作者 Jingjing Yang Yun Wang +4 位作者 Fangzhi Li Wenpu Huang Guanyi Jing Zemin Wang Xiaoyan Zeng 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第9期1817-1824,共8页
Laser welding is a promising process for joining small components produced by selective laser melting (SLM) to fabricate the large-scale and complex-shaped parts. In the work, the morphology, microstructure, microhard... Laser welding is a promising process for joining small components produced by selective laser melting (SLM) to fabricate the large-scale and complex-shaped parts. In the work, the morphology, microstructure, microhardness, tensile properties and corrosion resistance of the laser welded stress-relieved SLMed 304 stainless steel joints are investigated, as the different sections of stress-relieved SLMed 304 stainless steel are joined. Results show that the SLMed 304 stainless steel plates have a good laser weldability. The microstructure of laser-welded joints consists of the cellular dendrites in austenite matrix within columnar grains, exhibiting a coarser dendrite structure, lower microhardness (~220HV) and tensile properties (tensile strength of ~750 MPa, and area reduction of ~27.6%), but superior corrosion resistance to those of SLMed plates. The dendrite arm spacing of the joints varies from ~3.7μm in center zone, to ~5.0 (xm in fusion zone, to ~2.5 in epitaxial zone. The SLMed anisotropy shows a negligible effect on the microstructure and performance of the laser-welded joints. The laser welding along the building directions of the SLMed base plates can induce a slightly finer dendritic structure and higher tensile properties. 展开更多
关键词 SELECTIVE LASER MELTING LASER welding 304 STAINLESS steel ANISOTROPY
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈