光源编码的白光散斑剪切干涉计量术

本文提出了一种用非相干光源照明进行剪切干涉计量的方法—光源编码的白光散斑剪切干涉计量术.它采用光栅对光源进行编码以提高空间相干性,使物体的两个剪切像的波面部分相干叠加,以实现剪切干涉.     

研测动态问题的旋转孔径散斑照相法Ⅱ:矩位、平四位、直三位孔径

本文提出了旋转孔径散斑照相法中三种新颖的基本孔径:矩位孔、平四位孔和直三位孔,进行了理论分析和实验证明。采用新孔径拍摄散斑照相,散斑信息利用率高,衍射晕能量分布合理,信噪比提高,因而散斑条纹清晰度得到改善,相应的实验误差减小。     

Transformation of the spectrum of the longitudinal modes of a semiconductor laser on introduction of its radiation into fiber light guides

We investigated the influence exerted by the radius of the bend of fiber light guides with light-transmitting cores of different diameters on the transformation of the spectrum of longitudinal modes of the semiconductor laser radiation introduced into them. It is shown that the bended segment of the light guide acts as a spectrum selector, and the spectral composition of the radiation at the output of a light guide is different in different spots of the speckle structure. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 260–263, March–April, 2000.     

Electronic speckle pattern interferometry analysis of tensile tests of semihard copper sheets

Uniaxial tension tests of semihard copper sheets were studied by means of electronic spekle pattern interferometry (ESPI). The setup allowed the authors to analyze in detail the transitions from elastic to plastic behavior and from homogeneous to inhomogeneous plastic deformation. In agreement with the conventional definition of the yield point for copper fully plastic behavior starded at permanent strains close to 0.005. The strain-hardening coefficient was very low at the early stage of plastic flow (“easy glide”), increasing progressively until values on the order of 0.13 to 0.14 were reached at maximum load. A this point, the appearance of unequally spaced fringes signaled the beginning of inhomogeneous deformation. With ESPI, this occurrence may thus serve as a criterion to establish the forming limit of the material.     

CAE-based compensation methods of non-uniform pulse laser beam profiles

Applying the pulse laser to speckle methods, non-uniformities of the laser beam profiles and the intensities between each laser pulse have unpleasant consequences on the intensity distribution of the recorded images and following on the assigned fringes of the corresponding subtractive result. This contribution introduces a computer-based technique for compensating this technical and physical problem, so that the fringe quality is improved, even if the homogeneity of the laser beam profiles is on such low level, that the conventional (subtractive) technique fails. The solution is based on algorithms, which refines each intensity distribution and is comparable with the known shading correction.     

Polarizing interferometer with constant radial and azimuthal shears

An interferometer is described in which a rotatable Wollaston prism is used to achieve constant radial and azimuthal shears in a converging beam. These displacements may have applications in speckle shearing interferometry for the deformation measurement of objects with axial symmetry.     

一种抑制合成孔径雷达图像相干斑的各向异性扩散滤波方法

本文提出了一种抑制合成孔径雷达图像乘性相干斑噪声的各向异性扩散滤波新方法.该方法将受自适应耦合函数控制的平均曲率运动嵌入到传统相干斑抑制的各向异性扩散方程中,形成了一种可有效抑制边缘区域相干斑与同质区块效应现象的各向异性扩散新方程,同时在新建的扩散方程中,引入了由改进Frost滤波与局部方向比率联合构建的一种带方向约束的新扩散函数,进一步削弱了块效应现象且明显改善了抑斑图像的边缘抖动扭曲问题.实验结果表明该方法在有效保护图像边缘的同时,能充分平滑同质区与边缘区域的相干斑,明显削弱块效应现象,有效改善抑斑图像边缘抖动扭曲问题,而抑斑图像无论视觉效果还是参数指标均比多种传统抑斑方法更具优势.     

旋转粗糙目标微运动特征识别技术

基于动态散斑技术的微运动特性识别在目标探测领域具有重要的研究价值.以粗糙面散射理论为基础,研究了旋转粗糙凸体目标的动态散斑时间相关函数,给出了旋转圆锥体目标动态散斑时间相关函数.将数值结果与相同条件下实验结果进行比较,验证了圆锥体目标时间相关长度的有效性.利用粒子群算法,反演出旋转圆锥体的旋转角速度和视线角.结果表明,该方法可识别旋转圆锥体范围为20°—90°之间的视线角值和范围为0.5—6 r/min的角速度值,为微运动特征识别提供理论和实验依据.     

水下高斯界面背向散射超声散斑场的相位奇异

为了精确描述超声散斑场的特性,提出了采用计算机模拟产生超声散斑场的方法.利用模拟产生的高斯相关随机表面,获得了这类表面远场超声散斑场,同时得到了声强分布和相位分布.与实验产生的散斑场进行对比,建立了超声散斑场接收的实验系统,取与计算模拟相同的参数,获得了实验散斑场.通过对比发现:计算机模拟产生的超声散斑场相位存在奇异点,奇异点周围相位分布类似漩涡,计算机模拟产生的散斑场与实验得到的散斑场强度分布相似,强度值比实验产生的散斑场强度大,携带有用信息的高亮散斑较多,暗点较少,更利于研究和分析.     

菲涅耳深区散斑强度统计特性及演化

利用直透光波和高斯散斑场的叠加理论和基尔霍夫近似研究了菲涅耳深区散斑的构成,给出了菲涅耳深区散斑场及其强度概率密度和对比度的表达式.利用原子力显微镜测量的随机散射表面高度分布数据模拟菲涅耳深区不同散射距离处散斑,并计算绘出其强度概率密度和对比度曲线.理论与模拟相结合研究这两个统计函数的特征和直透光强所占比例的影响,以及它们随散射距离的演化规律.