同轴度误差的解析评定法与仿真研究

在介绍符合定义的同轴度误差解析评定法的基础上，着重对该方法进行了仿真研究，分析了安装误差、测量系统中的直行运支误差及其对仪器回转轴线的闰行度误差等对同轴度误差测量结果的影响。文中建立的同轴度误差解析评定数学模型和得出的结论为同轴度误差测量信和在线测量系统的研究提供了理论基础。     

一种新型大尺寸长度校准装置的研制

介绍了一种新型的大尺寸长度校准装置,该装置解决了激光干涉仪等高精度大尺寸长度测量仪器的实验室校准与溯源问题.通过采用三路相干光进行测长,根据两辅助光路与主光路的测长偏差计算阿贝角,实现了阿贝误差的实时补偿.利用标准双频激光干涉仪测试了阿贝误差的补偿精度,35 m测量范围内的比对误差小于±3μm.测量精度达到了单光路同轴测量的水平.     

激光垂准仪竖轴与激光光轴同轴度室内测量的可行性分析

对激光垂准仪竖轴与激光光轴同轴度的测量方法进行探讨,针对性地提出一个室内测量方案,该方案的可行性分析结果表明其完全能满足普通型激光垂准仪的校准要求.     

非接触法在线测量和调整圆柱轴线同轴度研究

本文对圆柱同轴度的测量原理、圆柱同轴度调整方法作了详细分析.选择高精度激光位移传感器LK031来实现同轴度测量,由自编软件给出调整量,对测量仪器的误差分析表明,测量方案满足测量要求.     

激光同轴度测量方法研究

研发了一种激光同轴度测量系统.建立了一套数学模型,分析了3种不对中情况下的轴-轴同轴度测量方法,推导了测量方程,实现了只需在小角度范围内旋转即可得出轴-轴同轴度的平偏量和角偏量.并提出了孔-孔同轴度的测量方法,实现了用一套设备可以同时测量轴-轴、孔-孔同轴度.     

新型超光滑表面粗糙度测量系统

本文介绍了一种新型的测量超光滑表面粗糙度的共光路偏振干涉系统。该系统以双折射透镜作为分光元件;采用偏振干涉方法和偏振接收方法对被测光学表面高度变化,实现高灵敏度、非接触探测,垂直分辨率为0.1nm。给出了系统结构,叙述了测量原理。     

车床尾座同轴度误差快速高精度测量方法研究

针对现场环境下的车床尾座孔与主轴之间的同轴度误差检测与调整问题,提出了一种基于激光准直和光电检测的同轴度误差快速高精度测量方法,并设计了以位置敏感探测器(PSD)和准直光束为核心的测量系统。通过分别驱动激光准直模块和光电测头旋转,PSD采集准直光束的轨迹信息,使用基于RANSAC的椭圆拟合改进算法,拟合轨迹中心点坐标。驱动尾座套筒沿轴向移动,测得多个截面的中心点,从而拟合轴线。最后,依据同轴度误差评定的最小包容区域准则,计算同轴度误差。在同一位置进行同轴度测量实验,测量系统的不确定度优于0.0032 mm,重复测量误差小于0.01 mm,满足车床尾座调整的同轴度测量要求。     

同轴度误差的非接触精密测量方法

根据夫朗和费单缝衍射原理，以激光作光源，采用线阵CCD获取衍射条纹图像，实现同轴度误差的非接触自动测量。通过对比测量和精度分析表明该方法测量精度高，测量装置结构简单，具有实用价值。     

两探测面结构激光粒度仪的接收光路设计

为了扩大激光粒度仪测量的动态范围,采用同轴的两组接收透镜,将两个硅光电探测器阵列分别置于前组透镜的后焦面和两组透镜的组合后焦面上,对测量信号进行组合后用改进共轭梯度法处理数据。通过优化光路结构,采用两组双胶合透镜和探测环半径均不大于45mm的探测器可满足同时测量5～3500μm粒径的要求。     

一种针对频率扫描测量系统的信号处理方法

设计了一种针对频率扫描绝对距离测量系统的信号处理算法。该系统采用基于电流调制式的频率扫描方法,利用一个比对干涉光路与一个测量干涉光路进行同步测量。两路扫描干涉信号分别由两个光电探测器进行光电转换,作为绝对距离计算处理的输入信号。分析了测量系统的原理与扫描干涉信号的特点,应用两步差分卷积算法进行信号处理,提取的比对光路与测量光路的周期或频率信息进行绝对距离测量。分析了该算法的周期计算误差。实验验证这种方法具有较大的计算优势。     

激光束角漂移对双频激光直线度测量的影响

利用惠更斯关于波面传播的理论，分析计算了双频激光渥拉斯顿棱镜直线度测量系统中激光束角漂移以及渥拉斯顿棱镜和双面反射镜倾角对测量精度的影响，得到了相应的结论。     

Division-of-amplitude Photopolarimeter (DOAP) for the Simultaneous Measurement of All Four Stokes Parameters of Light

To measure all four Stokes parameters of a light beam simultaneously, the beam is divided into four separate beams using a beamsplitter and two Wollaston prisms. Linear detection of the light fluxes of the four component beams gives four signals that determine the four Stokes parameters. This division-of-amplitude photopolarimeter (DOAP) is completely characterized by a wavelength-dependent 4 2 4 matrix that can be determined directly by calibration. The instrument has a fast response (that is limited only by the photodetectors) as it has no moving parts or modulation.     

Wollaston棱镜方位对激光干涉测量精度的影响

在双频激光干涉测量系统中,Ｗｏｌｌａｓｔｏｎ棱镜是不可缺少的重要光学元件,它可将双频激光按偏振方向分为测量光和参考光,从而实现高精度测量;但是,如果Ｗｏｌｌａｓｔｏｎ棱镜的安装方位相对入射光线方向以及与聚集透镜距离不同时,测量结果将会不同。本文结合表面粗糙度激光测量系统,从理论上定量分析了Ｗｏｌｌａｓｔｏｎ棱镜的安装方位对测量精度的影响。     

Fast fabrication of silicon based microstructures using 355 nm UV laser

Abstract

In this study, a 355 nm UV Nd:YAG laser is used to process silicon wafers. In order to obtain microstructures with high aspect ratio, a dual prism optical system is set up to control the cutting linewidth of the UV laser beam. During the laser beam propagation through the prisms, the two prisms are rotated with the same angular velocity, which results in the focal spot of the laser beam moving in a circular path on the silicon substrates. When the laser beam moves relative to the holder (workstation), a laser cutting process can be carried out. With this laser system, the cutting linewidth is controllable ranging from 10 μm to 1 mm by adjusting the initial phase difference in the two prisms. The experimental results show that arbitrary shaped silicon based microstructures with high aspect ratio can be fabricated by this 355 nm UV laser system, and the aspect ratio over 10 can be obtained.     

亚微米聚焦离子束的漂移现象

研究了亚微米聚焦离子束（FIB）系统的漂移现象，给出了测量漂移的方法，分析引起漂移的原因及降低漂移的措施。发现了偏转电极上钝化层及污染物充电电荷所引起的漂移现象；测出了各电极电压变化所引起漂移的大小；发现了由于外壳温度不均匀引起离子枪轴线相对样品变化所引起的漂移。提出了制作透镜电极时保持轴对称、特别是限制光栏必须位于透镜光轴上的必要性。所给出的漂移数据既包含早期曾研制的单级透镜FIB系统的数据，也包含近期研制的二级透镜可变束流FIB系统的数据。     

Aberration correction by nonlinear beam mixing: generation of a pseudo point sound source

Nonlinear beam mixing with microbubbles was explored to create a pseudo point source for aberration correction of therapeutic ultrasound. A damping coefficient for a bubble driven by a dual frequency sound field was derived by revisiting Prosperetti's linearized damping model. As a result, the overall damping term for dual frequency was obtained by linear summation of two damping terms for each frequency. The numerical simulation based on the bubble model suggests that the most efficient size range to generate a 1 MHz frequency from 4 MHz and 5 MHz sound sources is 2.6 to 3.0 microm. Furthermore, this size range constitutes the primary distribution of a specific ultrasound contrast agent. When a chamber of 0.1% of the diluted agent is sonified by 4 MHz and 5 MHz sound beams with 80 degrees incident angle between them, an approximately 100 Pa, 1 MHz difference frequency signal can be measured approximately 10 cm away. In addition, the received 1 MHz difference frequency signal shows omni-directional characteristics, even though the overlap zone of the two sound beams is on the order of the difference frequency wavelength. Therefore, the induced sound source can be considered as a pseudo point source and is expected to be useful for aberration correction for therapeutic ultrasound.     

Total internal reflection for precision small-angle measurement

A method for precision small-angle measurement is proposed. This method is based on the total-internal-reflection effect of a light beam at a pair of glass prisms. Angular displacement of the light beam is measured when the intensity change of the reflected beam is detected as a result of the relative phase shift between the s- and the p-polarized beams. An initial phase shift between the s- and the p-polarized components is introduced to increase measurement sensitivity. For increased measurement linearity and reduced effect of laser power fluctuation on the output, a differential method is used in which the light beam is split equally into two beams, each reflected at a prism and detected by a photodiode. The output is obtained as the difference of the two detected intensities divided by their sum. A prototype device was built, which demonstrated a nonlinearity error of 1.3% in a measurement range of ?0.6 degrees or 0.4% in ?0.3 degrees . The peak-to-peak noise level was found to be at approximately 0.5 arc sec. This noise level can be reduced further and resolution increased by a reduction of the measurement range.     

双端差分吸收激光雷达系统

研究和设计了一实验性双端差分吸收激光雷达系统。其光源为一台双波长双脉冲可调谐Cr:LiSAF激光器,利用BBO晶体腔内倍频和腔内调Q技术,实现了二次和三次谐波输出;激光系统的合作目标为远处一平面镜,光源发射光脉冲和信号采集由微机系统控制。该系统用于测量大气中的NO2和SO2的浓度分布。     

双Wollaston棱镜的光程差及其色散

深入研究了的光程差与棱镜楔角以及空间变量-入射角三者的关系,并进行了计算机模拟.发现了对方解石构成的双Wollaston棱镜,光程差有较大的变化范围,光程差和入射角的关系有较好的线性的条件是:棱镜楔角在22°附近,入射角在-50°到10°范围内变化.然后对光程差的色散特性进行了分析和计算机模拟,结果表明,双Wollaston棱镜的光程差明显依赖于光波长,根据拟合结果它们的关系可以用三阶多项式来表述.本结果为偏振型空间调制干涉光谱仪的设计和应用提供了理论依据.     

Continuous variable entanglement measurement without phase-locking

In this work, we propose a new simple entanglement measurement scheme, which can be utilized to take a measurement for the bright EPR beams generated by a nondegenerate optical parametric amplifier. Owing to the output signal and idler modes being frequency degenerate and in phase, one need not take a measurement for the signal and idler modes, respectively. By virtue of a quarter-wave plate and a half-wave plate, and then inserting a polarizing beam splitter, one can realize the measurements of the correlated phase quadratures and anti-correlated amplitude quadratures, simultaneously. Therefore, phase-locking and local oscillators are avoided.