电子束泵浦准分子激光放大器的双程光路自动准直

提出了一种电子束泵浦准分子激光放大器的双程光路准直方法,以保证光束在放大器中按照预定方向传输,并使多路光束稳定精确地照射靶面.首先,鉴于准分子放大器中无天然准直基准提出了利用双叉丝像传递光路进行准直的方法,即把输入光束叉丝基准作为“近场点”,把输出光束叉丝基准作为“远场点”,并设计了放大器准直光路,编写了相应的软件.然后,在现有实验室条件下开展了电子束泵浦准分子激光放大器双程光路的自动准直实验.最后,分析了影响该方法的相关因素及准直精度.实验及分析表明,设计的准直系统在较短时间内实现了预定传输光路的自动准直,系统自身精度为0.63μrad,光束最大复位误差为13.75 μm,满足了电子束泵浦准分子激光放大器双程光路自动准直的要求.     

激光准直扩束设计和仿真

从哈特曼法自动测量像差所需解决的准直(平行)光束出发,基于高斯先学理论,从工程角度分析了大倍率准直扩束系统的原理,实现了改变激光光束直径和发散角的准直扩束系统的设计,并通过仿真得到了验证,满足了光学系统的哈特曼像差测量要求.     

基于二维PSD的激光准直系统研究

提出了一种以二维位置敏感传感器(PSD)作为反馈元件来实现激光光束自动准直的设计方案,同时建立了测量控制系统的数学模型。经过测试与理论分析,激光光束的准直控制范围不大于20μm,且此准直系统具有结构简单、调节快速的特点,可以广泛用于零件形位误差检测与机械安装调试过程中快速建立光学基准。     

基于二维PSD的激光准直系统研究

提出了一种以二维位置敏感传感器（PSD）作为反馈元件来实现激光光束自动准直的设计方案,同时建立了测量控制系统的数学模型。经过测试与理论分析,激光光束的准直控制范围不大于20μm,且此准直系统具有结构简单、调节快速的特点,可以广泛用于零件形位误差检测与机械安装调试过程中快速建立光学基准。     

高斯光束的光学变换

本文从高斯光束和几何光学概念出发,分析了光学系统传输高斯光束的参数选择原刚,提出了某些设计要求。并以准直系统为例分析了激光准直系统对高斯光束的变换特性,还推导了光束扩展比的一般关系式。     

高精度激光光束准直系统设计

为了进一步提高激光光束用作直线基准的精度,建立了基于反射镜平动式光束稳定器以及两点式光束漂移分离法的高精度激光光束准直系统。首先,对系统中基于反射镜平动的光束稳定器进行研究,对其光束偏转原理以及影响因素进行分析,并对两点式光束漂移分离方法进行介绍。然后,对光束偏转单元的分辨力以及偏转范围、所使用的压电陶瓷非线性和迟滞特性、以及光束偏转单元的频率响应特性进行实验测试。最后,对该激光准直系统的激光光束准直精度进行测试。实验结果表明本文提出的光束偏转单元在120μrad范围内的光束偏转分辨力可以达到5 nrad,频率响应特性高于2 kHz;最终激光准直系统的准直精度在二维方向上分别达到1.9×10^-8 rad和2.1×10^-8 rad,相对于现有技术约提高了3倍,满足激光光束用作高精度直线基准的需求。     

热透镜效应对激光光束准直的影响

利用高斯光束传播定律,分析了热透镜效应对激光光束准直的影响,对两种不同的腔型做了数值模拟与计算,并计算了经具有不同MT因子的调焦望远镜系统准直后的激光光束的发散角与光斑尺寸。通过计算与分析表明,对于同一高斯光束,用MT因子较大的系统可以获得更好的准直效果,准直后光束的发散角更稳定。     

多波长激光扩束器的光学设计

在激光雷达以及光谱仪定标时常常需要较宽以及高准直性的激光光束。设计了一出射光束为16mm,扩束比为20倍的激光扩束器光学系统。通过移动激光扩束器的物镜与目镜间隔,可以实现光谱范围在543.5~850nm的激光扩束;比较了使用该激光扩束器发射的准直激光束与理想的单色平行光充满成像光谱仪的入瞳孔径后成像光谱仪传递函数的变化,说明该光学系统可行。     

LD准直透镜光能耦合效率与波差的理论分析

ＬＤ准直透镜光能耦合效率与波差的理论分析陈海清，阮玉，常洋燕（华中理工大学）０引言激光二级管发射的光束是发散的，需经过椭圆光束准直，整形及象散校正，从而获得发散度小准直度高的光束，同时还要考虑系统的光能利用效率与波差问题。准直透镜的作用是把ＬＤ所发出...     

LD光束准直方法研究

半导体激光器(LD)用于成像系统的时,要对光束的发散角进行压缩才可以使用。目前常用的几种LD光束准直设计方法数值计算过程繁琐,设计完成后的加工成本昂贵。当工作条件对光束的准直度要求不高,且只要求目标尺寸与投射光斑大小匹配时,可将LD视为一个理想点光源;当这个点光源在理想凸透镜的前焦点处时,光束经透镜作用后,变换为平行光。点光源由前焦点处向柱透镜移动,光束发散角会增大。Zemax用于调整LD和柱透镜的距离,模拟出目标处光斑大小,最终使光斑大小与目标尺寸匹配。根据仿真结果选取合适的产品,这种设计缩短了设计周期。     

MAST YAG Thomson scattering upgrade alignment system

The recent upgrade to the MAST YAG Thomson scattering while enhancing the diagnostic capabilities increased the complexity of the system. There are eight YAG lasers now operational, doubling the number from the previous setup. This means alignment between each laser individually and reference points is essential to guarantee data quality and diagnostic reliability. To address this issue an alignment system was recently installed. It mimics the beams alignment in MAST by sampling 1% of the laser beam that is sent into a telescope which demagnifies by a factor of 8. The demagnified beam is viewed with a CCD camera. By scanning the camera the profile and position of the beams in the scattering zone and in a range of several meters inside MAST can be determined. Therefore alignment is checked along the beam path without having to sample it inside the vessel. The experimental apparatus and test procedures are described.     

Experimental study of new laser-based alignment system at the KEK B-factory injector linear accelerator

A new laser-based alignment system for the precise alignment of accelerator components along an ideal straight line at the KEK B-factory injector linear accelerator (linac) is under development. This system is strongly required in the next generation of B-factories for the stable acceleration of high-brightness electron and positron beams with high bunch charges and also for maintaining the stability of injection beams with high quality. A new laser optics for the generation of a so-called Airy beam has been developed for the laser-based alignment system. The laser propagation characteristics both in vacuum and at atmospheric pressure have been systematically investigated in an 82-m-long straight section of the injector linac. The laser-based alignment measurements based on the new laser optics have been carried out with a measurement resolution of ±0.1 mm level by using an existing laser detection electronics. The horizontal and vertical displacements from a reference laser line measured using this system are in good agreement with those measured using a standard telescope-based optical alignment technique. In this report, we describe the experimental study in detail along with the basic designs and the recent developments in the new laser-based alignment system.     

Procedures for focusing,stigmating and alignment in high resolution electron microscopy

Several different approaches to the alignment, stigmating and focusing of a high resolution electron microscope are evaluated theoretically and experimentally. Ambiguities in the interpretation of diffractograms are pointed out which make it necessary to explore a range of incident beam directions before the correct alignment can be established. The variation of image contrast with the imaging conditions is examined in detail, and its global minimization is shown to be a reliable criteria for adjustment of all parameters. Recommendations are made as to the best procedures to adopt in various circumstances, and a computer-controlled procedure based on the image contrast is described which sets all parameters automatically in less than a minute.     

激光聚变冲击波被动式测速光学系统设计

针对激光聚变装置冲击波速度被动测量的需求,设计了一种测速光学系统。采用高紫外透过率的氟化玻璃,实现了透射式300～800nm复消色差设计。系统光路具有前后两组镜头,中间为平行光,镜头间距可变,光路适应能力强。系统前端两侧的双目机器视觉能够完成自动寻的。平行光路中设置5个激光器,轴上的1个前向照明靶点用来观察条纹相机狭缝处的目标像质,轴外的4个与光轴平行后向传输用来标识系统光轴的位置,激光器部件可电动切入/切出。系统前组镜头F/#数为4,宽谱工作物方分辨率优于10μm,532nm单波长工作物方分辨优于5μm。该光学系统光路排布灵活,可单独被动测速,也可与主动测速系统VISAR耦合构成主被一体复合测速系统,满足激光聚变装置冲击波测速的需求。     

High power rapidly tunable system for laser cooling

We present a laser configuration capable of fast frequency changes with a high power output and a large tuning range. The system integrates frequency tuning with an acousto-optic modulator with a double pass tapered amplifier. A compensation circuit keeps the seed power constant and prevents damage to the amplifier. A single mode fiber decouples the modulation and amplification sections and keeps the alignment fixed. The small power required to saturate the amplifier makes the system very reliable. We use the system to obtain a dipole trap that we image using a beam derived from the same configuration.     

An automated image alignment system for the scanning electron microscope

We have developed an automated image alignment system for the scanning electron microscope (SEM). This system enables specific locations on a sample to be located and automatically aligned with submicron accuracy. The system comprises a sample stage motorization and control unit together with dedicated imaging electronics and image processing software. The standard SEM sample stage is motorized in the X and Y axes with stepping motors which are fitted with rotary optical encoders. The imaging electronics are interfaced to beam deflection electronics of the SEM and provide the image data for the image processing software. The system initially moves the motorized sample stage to the area of interest and acquires an image. This image is compared with a reference image to determine the required adjustments to the stage position or beam deflection. This procedure is repeated until the area imaged by the SEM matches the reference image. A hierarchical image correlation technique is used to achieve submicron alignment accuracy in a few seconds. The ability to control the SEM beam deflection enables the images to be aligned with an accuracy far exceeding the positioning ability of the SEM stage. The alignment system may be used on a variety of samples without the need for registration or alignment marks since the features in the SEM image are used for alignment. This system has been used for the automatic inspection of devices on semiconductor wafers, and has also enabled the SEM to be used for direct write self-aligned electron beam lithography.     

分体式激光扩束系统平行度测量装置的设计

为精确测量强激光发射系统中高功率激光经分体式扩束系统后光束的传输方向,设计了一种新型分体式扩束系统输出光平行度测量装置.根据高功率激光分体式扩束系统及红外激光的特点,该装置采用高分辨率红外CCD作为监测成像设备.采用轻质高刚度的优质铝合金对装置的机械结构进行了设计,切换部件搭载在高精度线性位移平台上.基于高分辨率CCD和精密线性位移平台,该装置可较好地完成动态和静态测量.测试结果表明,该平行度测量装置工作稳定、可靠,测量精度优于2.0″;装置设计合理,实用,可为扩束系统的装调及应用提供可靠依据.     

大功率光纤传输连续激光焊接系统

介绍了大功率Nd:YAG光纤传输连续激光焊接系统的设计原理，特性及其在工业中的应用，利用四棒串接，动态调整等技术在国内率先获得了1280W的固体激光输出，采用光纤实现了大功率激光的远距离柔性传输；提供了大板拼焊的激光设备。     

基于球壳聚焦阵列的超声成像检测技术研究

为提高超声成像对比度和分辨力,研究了一种利用球壳聚焦阵列进行目标散射成像的方法。球壳聚焦阵列中的部分阵元发射聚焦声波,声波作用于目标后发生散射,回波被余下的阵元所接收,阵列中的发射阵元和接收阵元随机选择,以达到抑制旁瓣的作用。借助三维自动扫描机构,可获得聚焦波束沿被测物体表面的散射回波强度,从而实现对目标的成像。计算机仿真结果表明,球壳聚焦阵列可减小主瓣宽度,并有效降低聚焦波束旁瓣。水池实验结果表明,基于该阵列的散射成像方法具有亚毫米级的成像分辨力,能够获得较高对比度的图像。