基于PSD的高精度光电定心仪

针对目前定心仪精度不高、并依赖于人眼的现状,提出一种基于PSD的高精度定心仪研究方法。采用自准直光路形式和位置敏感探测器PSD对经过被测目标返回的光斑实行定位,并通过读取计算机上的坐标值来判断是否达到准确的定心。文中对定心仪的光学系统进行设计,并运用神经网络的训练来校正PSD的非线性,在测量范围2 mm~500 mm内定心精度达到1 m的设计要求。     

新型反射式激光定心仪探讨

文章介绍了一种新型反射式定心仪,探讨了定心原理,进行了精度分析,给出了实验结果。     

光学电视磨边定中心仪

随着我国电视工业的迅速发展,工业电视的应用越来越广泛。光学电视磨边定中心仪是工业电视应用于光学冷加工的具体实例。磨边定中心为什么要采用工业电视?它的优点是什么?这得从传统的磨边定中心方法谈起。一、传统磨边定中心方法的精度及其弊病在光学冷加工中,透镜磨边定中心的传统方法是将被定心透镜用松香粘在定中心磨边机主轴的夹头上,旋转被定心透镜,用肉眼观看远处灯泡两个反射灯丝象的跳动量,直到灯丝象不再跳动就说明透镜前后两面的曲率中心都落在机床主轴的轴线上,即透镜已定好中心,然后引进砂轮进行磨边。如果磨边机主轴没有     

非球面干涉定心方法研究

由于非球面光轴的唯一性,非球面定心工艺中需分别定义顶点偏心误差和球心偏心误差.通过估算顶点偏心在传统定心仪上的测量误差,可以发现传统定心仪很难达到控制目的,而干涉测量方法却能得到较高的准确度.理论推导和模拟计算表明：顶点偏心角与偏心彗差之间有线性关系,顶点偏心角的彗差灵敏度与非球面的陡度成正比.使用干涉检测的方法可以同时控制非球面的两种偏心误差,且其检测准确度可以达到0.02 mm.     

一种利用激光非定域干涉来控制面倾角的透镜定心法

本文探讨了使用He-Ne激光光源的透镜干涉定心法。导出了公式,并用实验进行验证。理论计算和实验证明:这是一种可以达到秒级精度的透镜定中心方法。     

二维定心激光扫描器及其摆角测量系统的研制

简要介绍了一种二维定心偏转激光扫描器的工作原理和结构设计。对二维摆角的两种不同测量方式的优劣进行了比较,并详细介绍了采用光电位置传感器(PSD)实现摆角测量的系统,包括它的测量原理、光学系统构造和PSD后续信号处理电路。结果表明,所研制的二维定心激光扫描器摆角测量系统可以实现±7.5°的二维摆角和30°圆锥角的大范围扫描,其重复精度为0 05°,分辨率为0 01°。具有快速灵巧、实时性强、工作稳定、抗环境干扰能力强等优点。     

柱面镜加工中母线偏差的校正

<正> 概述在球面镜加工过程中,球面镜的同心度精度直接影响球面镜的成象质量。对于成象要求较高的球面镜来说,同心度的偏差一般需在几个μm的数量级范围之内。由于球面镜定中心可以用透射式焦点象定中心仪,球心反射象定中心仪以及一些新型的定中心仪。借助于这些定中心仪,可以在磨边和定中心工序中消除球面镜的偏心现象,从而可获得成象质量高的光学系统。对于柱面镜的加工,关键的问题是如何消除母线偏差,而柱面镜的母线偏差比球面镜的中心偏更为复杂,校正方法也不完全同于球面     

摄影镜头的光学对心法

镜头的定心通常有三种方式:一是以镜框几何轴线为基准的定心法;二是修切定心法;三是以透镜光轴为基准的光学对心法。 第一种方法的定心精度取决于透镜和镜框的加工精度,如果其中之一同心度不高,则影响成象质量。 第二种定心法是镜框初加工时内孔及端面留有切削余量,此量在装配时修切,以纠正初加工偏心差,此时定心精度取决予透镜的滚边和胶合对心精度(对双合透镜而言)。若两者偏差小则象质就好,否则象质不好。     

高精度数字光电定心仪

本文论述了数字光电定心仪的工作原理,总体结构方案,光学系统,机械结构和电路原理以及试验与使用的结果。该仪器可用于磨边或胶合定中心和检验透镜中心误差。测量球心偏差精度可达1μm。     

大小接头的妙用

<正> 机械定中心是在一对同轴接头之间放入被定心透镜,借助弹簧力夹紧,使得透镜加工完毕具有相等的边缘厚度这一特征来实现的。在自动定中心磨边机上,一对制造十分精确、彼此轴线相互重合、直径大小相同的接头对机械定中心起的作用是很大的,但也可以用直径不同的一对接头来进行定中心,特别是当     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.