共查询到20条相似文献,搜索用时 250 毫秒
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Da-ping Wan Hong-bin Liu Yu-ming Wang De-jin Hu Zhen-xing Gui 《Optics & Laser Technology》2008,40(2):309-314
Laser texturing is a novel technique that may be used to texture a cold roller in the process of manufacturing high quality steel sheets. With the aim of improving the quality of the textured roller by using a CO2 laser, a new laser beam modulating device is proposed. An optical beam expander with a fast rotating chopper system is designed. The laser pulse is split into two parts by the chopper blades; one is the preheating pulse that is reflected onto optical loop mirrors; the other is the directly transmitted pulse that creates the craters at the preheated spots. The preheating beam focus spot size and position can be adjusted. The focusing characteristics and optical parameter compensation for the flying optics are investigated. The heat transfer and melt process of laser texturing are numerically simulated. The effects of the double pulses on the texturing are analyzed. The effect of preheating the sample ahead of the laser texturing pulse is examined. The surface profile and bump hardness show improvements by using this approach. 相似文献
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Suk Zhao B Sung Chung H Cho K Hyup Lee S Hwang S Yu J Ahn YH Sohn JY Kim DS Kyung Kang W Chung DS 《Physical review letters》2000,85(13):2705-2708
A cylindrical molecular lens is formed by focusing a nanosecond IR laser pulse. Trajectories of a CS2 molecular beam deflected by the lens are traced using the velocity map imaging technique. The characteristic lens parameters including the focal length, minimum beam width, and distance to the minimum-width position are determined. The laser intensity dependence of the parameters is in good agreement with theoretical predictions. Exciting possibilities for molecular optics and a new type of optical chromatography are opened up. 相似文献
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To achieve desired accuracy, precision and surface roughness during laser-material removal process, monitoring and control of the process parameters related to laser, optics, workpiece material and its motion are required. Focus position, defined as a gap between the focusing lens and the surface of the sample workpiece, is one of the most critical process parameters, which determines the projection of the intensity of the laser beam on the surface to be ablated and therefore directly affects volume and geometry of the material removed and there by machining quality. In this paper, acoustic emission (AE) generated by laser-material interactions was statistically analyzed with respect to the variations in the focus position. The study involved on-line measurements of the AE signal from the laser-material interaction zone as a function of the focus position and the width of the machined trenches. Several basic statistical parameters, e.g. average amplitude, variance and power spectrum density were analyzed to select distinct informational parameters. Pattern recognition analysis of three informational parameters based on variances within frequency diapasons of 20-180, 180-300, and 300-500 kHz was used for reliable classification of the focus position and width of the machined trenches. The results provide important information for future development of on-line monitoring and control systems for laser-material removal process. 相似文献
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Alexander Pichler Pierre Raymond Marc Eichhorn 《Applied physics. B, Lasers and optics》2014,115(3):325-334
In most applications of laser technology and optics the beam quality, the ability to focus a laser beam and the achievement of a good optical resolution play an important role. The compensation of distortions using adaptive optics requires fast wavefront measurement. Classical wavefront analysis schemes use matrix operations, which show a nonlinear computation time dependence with matrix size, making it difficult to achieve high-speed control loops at a high resolution. A novel wavefront sensor system is presented using a massively parallel k-nearest neighbor classifier chip in an embedded hardware setup. Our miniaturized sensor is able to detect one optical distortion within about 80 μs allowing its use for high-speed adaptive optics applications. 相似文献
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运用矩阵光学理论以及将硬边光阑窗口函数展开为有限个复高斯函数之和的方法, 对激光束辐照猫眼光学镜头时产生的猫眼效应机理进行了理论推导. 通过数值计算对猫眼效应的反射规律进行了分析, 并利用532nm激光辐照一个变焦范围为12—72mm的光学镜头进行了猫眼效应的实验验证, 从而得出了猫眼效应反射光特性与入射激光参数以及猫眼光学镜头的口径、焦距、离焦量等基本参数之间的关系. 研究表明, 猫眼效应反射光特性与猫眼光学镜头参数和入射激光参数密切相关, 且当猫眼光学镜头位于近场和远场的情况有很大不同. 根据入射光束
关键词:
猫眼光学镜头
猫眼效应
高斯光束
反射特性 相似文献
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This paper presents finite-element modelling simulations of thermal lensing and thermal lens compensation in transmissive optics for gravitational wave detectors. We compare the current candidate test mass materials, fused silica and sapphire, in terms of sample geometry and time-dependent phenomena. For both materials, the thermal-lensing time constant is a few minutes, yet the core temperature needs several tens of minutes to stabilize. Thermal lens compensation using simple radiative heating is limited in temperature by absorption in the test mass. This effect limits the maximum allowed absorption for sapphire to 10–20 ppm/cm. For reasonable parameters, optical path length compensation within 1 nm can be achieved over a beam radius of 5 mm. If the optical absorption of the transmissive optics is too high, compensation can be achieved by means of a separate compensation plate. PACS 42.25.Bs; 42.70.Ce 相似文献
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D. P. Hand M. D. T. Fox F. M. Haran C. Peters S. A. Morgan M. A. McLean W. M. Steen J. D. C. Jones 《Optics and Lasers in Engineering》2000,34(4-6):415-427
A non-intrusive optical sensor system has been developed for focus control of laser welding. This detects the light generated by the process through the laser delivery optics, and exploits the chromatic aberrations of these optics to detect any laser focal error at the workpiece. This system works for a wide range of materials and welding parameters, and example results are presented. The sensor has also been applied to laser ‘direct casting’, a process in which 3-D structures are built by flowing metal powder into a focused laser beam. In this case, melt pool temperature is also important, and so additional optics are incorporated into the sensor to provide a pyrometric temperature measurement which is used to control the laser power. 相似文献
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A tapered hollow waveguide that can focus a laser beam into a small beam spot is proposed for medical and dental applications. We fabricated hollow tapered optics by using a traveling torch, and the shape was formed as a precise linear taper. For a hollow taper tip with input and output diameters of 700 and 200 microm, respectively, the insertion loss is as small as 0.7 dB in a 10 mm long taper. The hollow taper optic producing a 200 microm spot withstands input energy of 100 mJ. Because a focusing lens is unnecessary at the output end, the laser beam can be introduced into a deep and narrow spot with these tapered optics. 相似文献
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Tobias LieseVolker Radisch Inga KnorrMichael Reese Peter GroßmannKlaus Mann Hans-Ulrich Krebs 《Applied Surface Science》2011,257(12):5138-5141
As a novel approach, the combination of pulsed laser deposition and focused ion beam was applied to fabricate different types of multilayer zone plate structures for soft X-ray applications. For this purpose, high quality non-periodic ZrO2/Ti multilayers were deposited by pulsed laser deposition on planar Si substrates and on rotating steel wires with layer thicknesses according to the Fresnel zone plate law. Linear focusing optics were fabricated by cutting slices out of the multilayers by focused ion beam and placing them directly over pinholes within Si3N4 substrates. Additionally, it was shown that laser deposition of depth-graded multilayers on a wire is also a promising way for building up multilayer zone plates with point focus. First experiments using a table-top X-ray source based on a laser-induced plasma show that the determined focal length and spatial resolution of the fabricated multilayer Laue lens corresponds to the designed optic. 相似文献
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In the high power laser facility, surface contaminations on the optics will worsen the laser beam quality and damage the optics. Particle and grease contaminations are two of the usual contaminations on the surface of optics. In this work, the 1064-nm laser induced plasma shockwave cleaning is utilized to remove SiO2 particle contaminations on the K9 glass surface. The results indicate the removal ratio can reach above 95%. The effects of parameters (particle position, laser gap distance and laser energy) on the cleaning efficiency have been studied in the case of single pulse laser cleaning. In addition, CO2 laser (10.6 μm) is utilized to remove the dimethylsilicone oil contaminations on the gold-coated K9 glass surface. The results show that CO2 laser can effectively remove the dimethylsilicone oil by properly controlling the laser parameters. The cleaned area increases with the increased laser power or irradiation time when the other parameters are constant. 相似文献
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Bao Y. Man Hong Z. Xi Chuan S. Chen Mei Liu Jing Wei 《Central European Journal of Physics》2008,6(3):643-647
Using a pulsed laser deposition (PLD) process on a ZnO target in an oxygen atmosphere, thin films of this material have been
deposited on Si(111) substrates. An Nd: YAG pulsed laser with a wavelength of 1064 nm was used as the laser source. The influences
of the deposition temperature, laser energy, annealing temperature and focus lens position on the crystallinity of ZnO films
were analyzed by X-ray diffraction. The results show that the ZnO thin films obtained at the deposition temperature of 400°C
and the laser energy of 250 mJ have the best crystalline quality in our experimental conditions. The ZnO thin films fabricated
at substrate temperature 400°C were annealed at the temperatures from 400°C to 800°C in an atmosphere of N2. The results show that crystalline quality has been improved by annealing, the optimum temperature being 600°C. The position
of the focusing lens has a strong influence on pulsed laser deposition of the ZnO thin films and the optimum position is 59.5
cm from the target surface for optics with a focal length of 70 cm.
相似文献
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A method for a beam shaping optics is proposed to convert a laser beam profile into arbitrary required intensity distribution.
Surface profile of the beam shaping optics is designed by using Snell's law to convert the required intensity distribution
at the beam irradiation plane from the input intensity distribution. A computerized numerical control (CNC) lathe is employed
to fabricate the beam shaping optics, and acrylic resin is used for the material. The acrylic resin plate is cut by a ball
type of grinding wheel tool consisted on diamond powder and polished by a cone type felt buff with alumina ceramics powder.
The CNC lathe is powerful tool to control the position of these tools. The fabricated beam shaping optics is aspheric shape
with 4 mm of thickness and it works to convert the intensity distribution of multi-mode beam profile with 13 mm of diameter
into a flat top cylinder with 1 mm of diameter. A working distance of the beam shaping optics is 60 mm, and its transmittance
is over 98%. It succeeds to fabricate uniform melting mark of 0.6 mm diameter on a steel target by the YAG laser process. 相似文献
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I. Peshko G. Galich M. Lopiychuk A. Khizhnyak V. Nakvasuk 《Optics & Laser Technology》1997,29(4):211-215
A laser system containing four CW Nd:YAG double-rod lasers, transforming optics and a fibre with input-output optics has been designed and investigated. It is shown that reduction of the beam parameter product of the non-Gaussian beams in the image space of the lens has made it possible to collect the emission of four lasers to the same fibre. Independent laser operation has provided the output power control in the range of 10–900 W with a stable light spot size on the input end of the fibre. 相似文献
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In this paper, a simple and accurate method based on Z-scan and parallel moiré deflectometry for measuring the focal length of microlenses is reported. A laser beam is focused by one lens and is re-collimated by another lens, and then strikes a parallel moiré deflectometer. In the presence of a microlens near the focal point of the first lens, the radius of curvature of the beam is changed; the parallel moiré fringes are formed only due to the beam divergence or convergence. The focal length of the microlens is obtained from the moiré fringe period graph without the need to know the position of the principal planes. This method is simple, more reliable, and completely automated. The implementation of the method is straightforward. Since a focused laser beam and Z-scan in free space are used, it can be employed for determining small focal lengths of small size microlenses without serious limitation on their size. 相似文献
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变形镜对千赫兹掺钛蓝宝石飞秒激光频谱相位补偿 总被引:2,自引:2,他引:2
尝试用光谱展宽的方法从频谱相位(而非时域相位)的角度利用变形反射镜来补偿1kHz飞秒激光系统输出光路的频谱相位畸变,从而提高飞秒激光脉冲的时域强度衬比度,改善其光束质量。频谱相位补偿实验是在一台1kHz掺钛蓝宝石飞秒激光系统输出光路中,针对超短脉冲光束通过传输介质后的频谱相位畸变,引入变形反射镜进行补偿。应用频谱相位干涉直接电场重构(SPIDER)方法和仪器作为测量手段,建立了一套相位测量补偿系统。实验结果表明用变形反射镜可使激光脉冲的相位畸变得到较好的补偿,脉冲的光束质量得到改善。这种方法的主要思想就是将相位补偿转换为空问的光程控制,控制简单且损耗很低,是自适应光学中具有应用前景的一种补偿方法。 相似文献