The Defocused Image of Sinusoidal Gratings

The defocused image of an infinite sinusoidal grating is calculated by scalar diffraction theory for a perfect optical system. It is shown that the image contrast for both circular and annular pupils and for either incoherent or partially coherent illumination can be found in terms of Incomplete Bessel and Struve functions. The results of some typical cases are given. The effect of limiting a grating to a finite number of periods is considered. The results are applied to a consideration of resolving power tests. L'image défocalisée d'une mire sinusoidale indéfiniment étendue est calculée dans le cadre de la diffraction (avec amplitudes scalaires) pour un instrument stigmatique. On montre que le contraste de l'image pour les pupilles circulaires ou annulaires en éclairage-incohérent ou partiellement cohérent peut être exprimé à l'aide des fonctions de Bessel et de Struve « incomplètes ». On donne les résultats dans quelques cas types. L'effet de la limitation de la mire à un nombre fini de traits est étudié. Des considérations sur les tests de pouvoir séparateur en résultent. Für ein ideales optisches System wird das unscharf eingestellte Bild eines unendlich breiten Sinusgitters aufgrund der skalaren Beugungstheorie berechnet. Es ergibt sich, dass der Bildkontrast für kreisförmige und ringförmige Pupillen und für inkohärente oder teilweise kohärent Beleuchtung mit Hilfe unvollständiger Bessel und Struwefunktionen dargestellt werden können. Für einige typische Fälle werden die Ergebnisse mitgeteilt. Der Einfluss einer Beschränkung auf eine endliche Zahl von Gitterperioden wird geprüft. Die Ergebnisse lassen sich auf die Untersuchung von Auflösungstesten anwenden.     

基于点扩散函数的散焦图像复原及其效果比较

针对已知的散焦图像数学模型,通过先估计点扩散函数(PSF),然后利用维纳滤波估计原始清晰图像的方法,探讨PSF、调制传递函数(MTF)的估计方法,具体包括边缘地物法、空间频率响应法、基于APEX方法的估计算法.结合复原图像的模糊度客观评价函数和主观视觉评价来判别各方法的优劣,结果表明:边缘地物法较优.     

发光二极管光强的测量

本文研究了发光二极管光强的测量，分析了测试距离和二种不同定标方式对精度的影响，建立了光强测试仪，精度为７．３％     

Precision of Measurement of the Coordinates of an Image on a CCD Matrix

The displacements of the light-sensing elements of a CCD matrix in the course of thermal stabilization after the CCD matrix has been switched on are measured. It is shown that the deformations in the matrix exhibit high isotropicity. The uncertainty in the determination of the coordinates of crosshairs on a CCD matrix is estimated and shown to be on the order of 1 nm.     

Image Intensity at the Edge of a Straight Edge Object

Abstract

We consider the value of the intensity image at the geometrical position of a general, flat, straight edge object. We adopt a Fourier optical transfer function approach and obtain, rigorously, analytic expressions for the cases of coherent, incoherent and equal aperture, partially coherent imaging. Aberration-free, circular pupils are considered and the analytic results are found to agree with earlier numerical calculations. We also obtain expressions for the intensity gradient at the edge.     

Measurement of the Relative Intensity of 103Pd Photon Radiation

The intensity of photon radiation with energies of 20.15, 22.77, 295, and 497 keV in the decay of ¹⁰³Pd has been measured relative to the 357-keV spectral line. The results have confirmed that there is a discrepancy between the evaluated data for ¹⁰³Pd KX and gamma radiation. An interrelated system of absolute intensities for those energies is proposed.     

采用罗奇光栅离焦投影的位相测量轮廓术

本文提出一种采用罗奇光栅离焦投影的位相测量轮廓术。给出由离焦引起的光学低通滤波和N-位相算法表征的数字滤波的解析描述。证明由于采用罗奇光栅离焦投影而引起的误差只具有很小量级,在大多数实际应用中可以忽略。文中给出了计算机模拟和实验结果。     

声强测量中系统误差修正的若干问题研究

本文对用残余声强法修正声强测量的系统误差进行了理论分析，推导了它的误差表达工式，给出了该误差的二元分布图。     

穿孔机导盘转速的建模与测量

介绍了狄塞尔导盘改造方法,并针对生产现场实时导盘转速难以快速准确测量的问题,建立了导盘转速模型,提出了基于速度观测器的间接测量方法.针对观测器中难于测量的导盘负载转矩问题,在MTPCR算法的基础上,提出了利用PSO优化算法寻找最优输入通道滞后时间的P-MTPCR算法,建立其软测量模型.将其与速度观测器相结合,形成基于的负载力矩软测量模型的速度观测器.仿真实验验明,该速度观测器可以得到精确的导盘转速,为它的快速准确控制提供了必要条件.     

图像传感测量在热成型工艺中的应用研究

介绍图像传感器对快速热成型工件的外径在线检测原理。通过对误差因素的实验验证和理论分析 ,给出一种适用的图像信号的综合误差补偿方法。该方法避开了难以检测的误差因素 ,借助易测的相关参量的在线估值 ,适时给出误差补偿量。该系统用于热工现场 ,测控精度满足工艺要求。     

基于成像式照度探测的光源光强分布测量

基于成像式照度探测的光源光强空间分布特性测量方法以其量值准确、大幅消除背景光干扰等优点,受到人们的广泛关注。本文根据成像式照度探测原理设计了一套光源光强空间分布特性检测装置,通过实验测试了该检测系统,并总结了测量位置与光强空间分布测量误差之间的关系。该系统具有很好的实用价值。     

一种新的三维矢量声强测量方法

在双传声器互谱声强测量方法的基础上,提出了一种4传声器三维声强矢量测量方法,并且针对实际测量系统存在的误差,给出了一种简单实用的标定方法。以单极子声源为例,对该方法在不同频率情况下的理论误差进行了仿真分析,结果表明：在5—2000Hz频率范围内,测量所得x、y、z3个方向的声强误差均不超过1．5dB。与传统测量方法相比,该方法有如下优点：所用探头结构简单,只需4个传声器,可以节约成本;可用于瞬态声强的测量;在规定的频率范围内具有较高的精度。     

离散傅立叶变换误差对声强测量技术的影响

离散傅立叶变换(DFT)存在误差。分析DFT泄露误差对声强测量的影响,进行模拟计算。计算结果表明:DFT泄漏误差将引起声强的泄露,在多个频率情况下还可能导致出现不合理的负声强。继而进行实验实测,实测结果与理论分析结论相同。     

Application of Stereo‐Digital Image Correlation to Full‐Field 3‐D Deformation Measurement of Intervertebral Disc

Abstract: This paper presents the application of a Stereo‐Digital Image Correlation (Stereo‐DIC) based approach for full‐field deformation measurements on a porcine intervertebral disc (IVD) under in‐vitro loading. Full‐field capabilities of Stereo‐DIC provide useful information on the IVD structure‐function relationship needed for designing novel disc replacement devices on the basis of biomimetic concepts. In this work, the use of a multi‐view Stereo‐DIC system allows full‐field measurement over more than 180° of the IVD surface. This is achieved by sequentially moving a single camera through seven fixed positions in order to cover the desired angle of vision. Ad hoc data processing and merging procedures are calibrated for a cylindrical sample. Strain maps are determined for a rubber cylinder subjected to rigid‐body motions and then to uniform compression. These preliminary procedures serve to evaluate strain‐mapping errors as well as to assess repeatability and accuracy of camera re‐positioning. Once the entire procedure is verified and calibrated, a fresh porcine functional spine unit is loaded under anterior, posterior and lateral compression. From displacement maps obtained with the multi‐view set‐up, it is possible to gather information on both IVD bulging and surface strains. Results are consistent with the IVD global behaviour under standard testing protocols reported in the recent literature. Furthermore, detailed information on local variations in structural response and stiffness properties occurring when load is applied in different regions of the IVD are obtained. The present approach allows to correlate structural response with the entire 3‐D deformation and strain field and not just with a single displacement/strain component and thus it could be effectively used for explaining in‐homogeneity observed in human discs degenerative patterns.     

激光散斑引起象强度中心漂移的计算机模拟

本文对这个基本不确定度进行了计算机模拟研究，所得模拟曲线与Ｒ．Ｇ．Ｄｏｒｓｃｈ，Ｇ．Ｈａｕｓｌｅｒ等人的研究基本一致。此外，还对基本不确定度与表面粗糙度的关系，基本不确定度与成象系统点扩散函数内所包含的相关单元的关系进行了研究。     

声强测试在装载机噪声源分析中的应用

声强测试分析方法是一种有效的噪声源识别和声场分析方法.采用声强测试技术对某轮式装载机进行噪声测量.得出其声场分布规律,快速准确地找到主要的噪声源,在此基础上提出具有针对性的降噪措施,获得令人满意的效果.     

Automatic Evaluation of Mixed-mode Stress Intensity Factors Utilizing Digital Image Correlation

Abstract:  A method for determining mixed-mode stress intensity factors from displacement fields obtained by digital image correlation is studied. To perform automatic evaluation, not only stress intensity factors but crack-tip location, higher-order terms in the series expansion of displacement fields and rigid-body displacement components are also determined simultaneously using nonlinear least squares based on the Newton–Raphson method. Experimental results show that the mixed-mode stress intensity factors are evaluated accurately from either radial or circumferential displacement components. As mixed-mode stress intensity factors can be evaluated easily, simply and automatically by the technique with digital image correlation and nonlinear least squares, it is expected that the proposed method can be applied to solve various fracture problems.     

水下声强测量分析系统及其在近场测量中的应用

基于双水听器互谱测量法,自行研制了可用于水下结构辐射噪声测量系统.该测量系统具有较宽测量频带范围,是一套以微型计算机为核心的声强测量系统,它包括声强探头、放大、滤波、A/D采集、电控系统等;并利用该系统在消声水池中进行了声强测量的试验研究,给出了测量面上的声强量值分布的三维图和等值曲线图.试验表明,该测量系统的测量结果是可靠的、测量的效率高.     

Investigations of the Influence of Hologram Aberrations on the Light Intensity Distribution in the Image Plane

The aim in this paper is to analyse, for the examples chosen, the influence of particular aberrations of the point-object hologram on the light intensity distribution in the plane which is assumed to be the image plane. The numerical method used for calculating the light intensity at any image point is that presented in an earlier paper. The calculations have been carried out for three cases of holographic imaging. The recording and reconstruction geometry has been chosen so that it was possible to examine the influence of the particular aberration on the image quality. The calculated energy distribution in the aberration spots is consistent with those resulting from using third-order aberration theory as well as from ‘ray-tracing’ calculations.