kHz dye laser for use with ultrafast laser systems

We have constructed a cavity-dumped dye laser optimized for use with kHz repetition rate ultrafast lasers for performing experiments on atomic and molecular systems. The dye laser is inexpensive, robust, and requires little pump energy, making it ideal for experiments requiring multiple excitations for state preparation.     

An industrial approach of laser polishing with different laser sources

Surface finishing of dies and molds is one of the most interesting applications of laser polishing process. Because of the variety of materials used in die and mold manufacturing, as well as the different surface topographies, in each case, it is necessary to use appropriate process parameters. The presented work focuses on the study of laser polishing process on three commonly used materials in the manufacture of dies and molds, such as tool steels AISI D2 and AISI P20, ductile cast iron GGG70L and LaserForm ST‐100, a specific material developed for plastic injection mold making. Experimental studies were carried out determining the influence of the energy density on the roughness reduction rate. A key point that has a direct impact on the resulting surface roughness is the initial surface finishing of the material before laser polishing. In order to determine the degree of influence, experimental studies were conducted on two steels, AISI H13 and AISI P20, which are typically used in mold making industry. The experimental tests showed that a random distribution of peaks and valleys allows more homogenous material melting and gives as result a smoother surface after laser polishing.     

LD端面抽运长方形激光晶体的热效应

通过对二极管激光器端面抽运激光晶体工作特点的分析,提出了长方形激光晶体热模型。在热模型中考虑了激光晶体具有沿轴向对称加热、周边恒温等特点。利用热传导方程得出了激光晶体内部温度场和端面热形变场的一般解析表达式。研究结果表明,若使用输出功率为18W的二极管激光器端面抽运Nd:YVO4晶体(钕离子掺杂质量分数为0.5%),抽运光斑为0.4mm时,长方形激光晶体抽运端面具有267.6℃的最大温升和发生6.2μm的最大热形变量。对激光晶体产生的温度场和端面热形变场的研究为解决晶体热透镜效应、提高激光器的性能起指导作用。     

不同光束移动速度下的激光淬火有限元分析

为研究不同激光淬火处理条件下激光淬火温度场和物相结构,运用ABAQUS/Standard对激光淬火处理AISI4140钢进行了有限元模拟,并结合实验进行了验证.结果表明：激光淬火材料最高温度并不在光束中心,而是出现在距激光束中心2 mm的位置,且不随着光束移动速度的增大而改变位置;在激光束最高温度恒定为1150℃情况下...     

Development of a pumping laser system for x-ray laser research

A two-beam chirped-pulse-amplification Nd:glass laser system dedicated to x-ray laser research is described. Each beam provides an output energy of 20 J with a typical pulse duration of 1.3 ps. A prepulse of variable duration is generated by use of a novel, to our knowledge, optical system. A reflection optical system, comprised of an off-axis parabolic mirror and a spherical mirror, produces a line focus with 6-mm length and 165-microm width without chromatic aberration. By use of this pumping laser system, the nickel-like silver x-ray laser at a wavelength of 13.9 nm has been demonstrated.     

Portable laser microanalyzer

A portable laser emission analyzer for real-time quantitative and qualitative analysis of chemical elements in solids substances and materials is described. Possible areas of its application are considered. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 33–36, July, 2000.     

Femtosecond laser speckles

The concept of femtosecond laser speckles is put forward. The theory of a speckle pattern in light of finite bandwidth is applied to describe femtosecond laser speckles. Basic representations of the contrast and the spectral correlation of femtosecond laser speckles are presented. The relationship between the speckle contrast and the bandwidth of a femtosecond laser is given. Experimental results are given that indicate an obvious difference between the speckle patterns produced by a continuous-wave laser and those produced by a femtosecond laser.     

Dual-focus laser micro-machining

This paper describes an optical configuration for generating dual-focus from a single laser incident beam. The generated two foci have nearly equivalent spot size and both fall on the optical axis of the focusing optics, but at different focal lengths. The dual-focus optics allows for variations of the laser power of each focal point and the distance between the two focal points. The advantages of dual-focus ablation were demonstrated with a nanosecond UV laser dicing silicon substrates. The experimental results show that, compared to conventional single focus, dual-focus improves ablation rate by a factor of 2–4.     

Stabilized helium-neon laser

Conclusions The results so far obtained indicate that the laser stabilized by the suggested method can be used as a secondary radiation source in interference measurements. Until more acceptable excitation conditions for the cell are obtained, the radiation wavelengths of such a source should be periodically checked against the isotope⁸⁶Kr wavelength.Translated from Izmeritel'naya Tekhnika, No. 1, pp. 31–32, January, 1968.In conclusion the authors should like to express their gratitude to A. N. Alekseeva, S. P. Borisovskii, and M. I. Kataev who actively participated in the above work.     

激光精度靶

立靶精度测试是轻武器精度实验重要的考核内容之一.激光精度靶是一种精确可靠的精度测量设备.特别是在水下武器的研制过程中,激光靶在水下特殊环境中使用时显示出的一定的优越性.本文主要概述激光精度靶硬件的结构以及软件的功能.并说明其在轻武器立靶精度测试中的先进性.     

Three-dimensional laser microvision

A three-dimensional (3-D) optical imaging system offering high resolution in all three dimensions, requiring minimum manipulation and capable of real-time operation, is presented. The system derives its capabilities from use of the superstructure grating laser source in the implementation of a laser step frequency radar for depth information acquisition. A synthetic aperture radar technique was also used to further enhance its lateral resolution as well as extend the depth of focus. High-speed operation was made possible by a dual computer system consisting of a host and a remote microcomputer supported by a dual-channel Small Computer System Interface parallel data transfer system. The system is capable of operating near real time. The 3-D display of a tunneling diode, a microwave integrated circuit, and a see-through image taken by the system operating near real time are included. The depth resolution is 40 mum; lateral resolution with a synthetic aperture approach is a fraction of a micrometer and that without it is approximately 10 mum.     

Wide-spectral-range laser refractometer

We present refractometric measurements made in the 266-1064-nm spectral region with a pulsed Nd:YAG laser, and the second, third, and fourth harmonics of the laser's fundamental wavelength. The critical angle is determined by the disappearance of the diffraction orders from a metal grating, forming a microcuvette with the prism's reflecting wall. A fused-silica measuring prism is used in the experiments.     

Biological laser action

The narrowing of the spectral linewidth and the increasing of the peak intensity characteristic of laser action were observed in emission spectra of dye-infused biological tissues. The tissue was infused with a solution of Rhodamine 640 perchlorate in ethanol and then excited with frequency-doubled Q-switched Nd:YAG laser pulses. The dependence of emission linewidth on the excitation radiant exposure and dye concentration was investigated. Laser action was also observed in biologically compatible fluorescein sodium dye dissolved in phosphate-buffered saline mixed with scattering polystyrene spheres. The sharp spectral peaks of laser action in tissues may find applications in the detection of superficial disease.     

Neural-network laser radar

A laser radar whose resolution is greater than 1 μm is reported. We present the radar results when they are used for such purposes as determining the size of a void inside a silicon wafer, profiling a cross-sectional pattern of an optical fiber, studying the birefringence of a lithium-niobate crystal, or finding a fault in an optical guide in an optical integrated-circuit wafer. Neural-network theory was used in processing the radar signal. Radar processing based on neural-network theory gave significantly superior resolution compared with Fourier-transform-based processing.     

Hankel-Bessel laser beams

An analytical solution of the scalar Helmholtz equation to describe the propagation of a laser light beam in the positive direction of the optical axis is derived. The complex amplitude of such a beam is found to be in direct proportion to the product of two linearly independent solutions of Kummer's differential equation. Relationships for a particular case of such beams-namely, the Hankel-Bessel (HB) beams-are deduced. The focusing of the HB beams is studied.