Fast Face-Recognition Optical Parallel Correlator Using High Accuracy Correlation Filter

We designed and fabricated a fully automatic fast face recognition optical parallel correlator [E. Watanabe and K. Kodate: Appl. Opt. 44 (2005) 5666] based on the VanderLugt principle. The implementation of an as-yet unattained ultra high-speed system was aided by reconfiguring the system to make it suitable for easier parallel processing, as well as by composing a higher accuracy correlation filter and high-speed ferroelectric liquid crystal-spatial light modulator (FLC-SLM). In running trial experiments using this system (dubbed FARCO), we succeeded in acquiring remarkably low error rates of 1.3% for false match rate (FMR) and 2.6% for false non-match rate (FNMR). Given the results of our experiments, the aim of this paper is to examine methods of designing correlation filters and arranging database image arrays for even faster parallel correlation, underlining the issues of calculation technique, quantization bit rate, pixel size and shift from optical axis. The correlation filter has proved its excellent performance and higher precision than classical correlation and joint transform correlator (JTC). Moreover, arrangement of multi-object reference images leads to 10-channel correlation signals, as sharply marked as those of a single channel. This experiment result demonstrates great potential for achieving the process speed of 10000 face/s.     

High-precision sub-pixel interpolation in particle image velocimetry image processing

The task of image interpolation and re-sampling for particle image velocimetry (PIV) is investigated, which is used for window shifting with sub-pixel accuracy and image or window deformation. A new interpolation scheme based on a Gaussian filter is introduced and compared with commonly used and widely accepted interpolation techniques in terms of the achievable root mean square deviation of the displacement estimates.     

一类基于通量分裂的二阶精度TVD差分格式

基于通量分裂和逆风特性，选取单元交界面上的正、负数值通量，并结合高阶Runge-Kutta TVD时间离散方法，构造了一维非线性双曲型守恒律的一类二阶精度的差分格式，证明了差分格式的TVD特性。按分量形式推广到方程组。通过几个典型的数值算例验证了格式的有效性。     

校准电表的一种方法

利用电位差计的高精度，设计出合理的实验电路对C31型电表进行校准，使得电表的准确度等级得以提高。     

压印光刻中的两步对正技术

压印光刻中套刻需要粗、精两级对正.实验采用一对斜纹结构光栅作为对正标记.利用物镜组观察光栅标记图像的边界特征进行粗对正,其准确度在精对正信号的捕捉范围内；利用光电接收器件阵列组合接收光栅莫尔信号，在莫尔信号的线区进行精对正.由于线性区的斜率大, 精对正过程中得到相应x,y方向的对正误差信号灵敏度高,利用高灵敏度对正误差信号作为控制系统的驱动信号,对承片台进行驱动定位,实现精对正.最终使X,Y方向上的重复对正准确度分别达到了± 21 nm(± 3σ)和±24 nm(± 3σ).     

基于液晶调制器调制的实时测温系统

分析了一种基于基尔霍夫定律的钽酸锂(LiTaO3)热释电探测器作为接收元件的实时测温系统中,机械式调制盘对测量精度影响,提出了改变机械式调制盘对测量精度的影响的方法;介绍了液晶调制器的结构、对辐射调制的原理以及在使用过程中的优点。设计了利用液晶调制器替代机械调制器的钽酸锂热释电实时测温系统。结果表明,利用液晶调制器改进后的测温系统在给定的温度范围中,测量精度均有明显的改善,符合测量要求。     

一种实用化实时测温系统的优化设计

基于基尔霍夫定律，利用半导体激光器及钽酸锂热释电探测器设计了一种实用化的实时测温系统。依照测温系统各主要技术指标(温度分辨力、温度的标准偏差及测温范围)与各主要技术参量(激光光源的能量、波长、放大器的带宽及光学系统的相对孔径等)之间的关系，对实时测温系统的各主要参量(激光光源的能量、光学系统的相对孔径及放大器的带宽)进行了优化设计。实验表明，在测温范围673～1473K内，温度测量的不确定度优于0．3％，分辨力优于0．4K，均符合设计要求。     

面阵探测器的像点亚像素定位研究

面阵探测器可直接探测点目标图像的位置，但其定位精度受到探测器分辨率的限制。因此，亚像元精度技术得到了发展。它是利用目标像点的灰度分布特性，通过内插细分算法，确定出像点位置。可将定位精度提高1—2个数量级。本文介绍了几种实现目标像点亚像素定位的内插细分算法。对它们的计算公式、特点进行了分析，并进行了实验验证。     

超薄反射镜支撑技术

运用有限元方法对一种超薄反射镜的多个支撑方案进行分析计算,其中包括支撑点数量及排布方式的合理选择、支撑组件的优化设计。分析结果表明:该超薄反射镜在自重下的面形精度通过多点调节能够满足要求,预示了将该支撑技术应用于超薄反射镜具有可行性,并为超薄反射镜结构在面形控制实验中实施主动调节提供了数值依据。     

In-time motion adjustment in laser cladding manufacturing process for improving dimensional accuracy and surface finish of the formed part

This paper presents in-time motion adjustment in laser cladding manufacturing process as a means to improve dimensional accuracy and surface finish of the built part. Defects occurring during laser cladding degrade the part quality such as dimensional accuracy and surface finish. In this paper, in-time motion adjustment strategy was presented to remedy and eliminate defects occurring during laser cladding to improve the dimensional accuracy and surface finish. Based on the relationship between the motion of laser head relative to the growing part and other parameters in effects on clad profile, the laser traverse speed, stand-off distance and laser approach orientation to the existing clad layer were adjusted by instructions from a close-loop control system in real time to remedy and eliminate defects. The results of the experiments verified the effects of in-time motion adjustment on dimensional accuracy and surface finish.