Optical vs. direct sorption and swelling measurements for the study of stiff-chain polymer-penetrant interactions

This work involves interferometric ‘optical thickness’ and refractive index measurements performed in an optical thickness meter (OTM), on supported cellulose acetate (CA) films equilibrated with various activities of methylene chloride (MC) vapor. The relevant equilibrium sorption and volume swelling isotherms were determined by application of the Claussius-Mossotti equation on the assumption that these films swell unidimensionally along the thickness direction, and were compared with corresponding direct equilibrium sorption (weight gain), elongation and thickness dilation measurements on similar free films performed in a vacuum sorption/swelling apparatus (VSA) and complemented with refractive index data. Combined elongation and thickness dilation data from the VSA showed that free glass-cast CA films exhibit pronounced swelling anisotropy. The said anisotropy, although it cannot be completely eliminated, by conditioning at high degrees of swelling, does not appear to affect the extent of volume swelling significantly, thus permitting quantitative comparison of sorption and swelling isotherms determined by the VSA and the OTM. Such comparison showed satisfactory agreement between these two sets of results up to an MC uptake of ca. 0.4 gMC/cm³ of dry CA corresponding to a degree of swelling of ca. 0.2. Increasing discrepancies are observed at higher MC concentrations, which are attributable to breakdown of the assumption used that the supported films swell unidimensionally along the thickness direction. The present CA-MC volume swelling data exhibit the negative deviation from volume additivity on mixing typical glassy polymers.     

复合材料断裂力学参量的实验测定

本文采用三维云纹干涉仪同步测量含裂纹复合材料弯曲板的面内位移场及离面位移场，并对离面位移场云纹图进行计算机自动采集和处理，编制了云纹数字图像处理软件。文中推导了正交异性复合材料弯曲问题的离面位移场表达式，得到了弯曲板裂纹尖端位移w与应力场强度因子K1的关系式。通过实测位移，结合裂尖位移场推导出应力强度因子K1值。     

CO2激光干涉检验轮胎面面形及双曲率半径

轮胎面属于高次非球面,不同于二次回转球面,在光学系统中具有独特重要的用途,但至今无有效的面形检验方法.本文用自行研制的移相式CO₂激光(λ=10.6μm)球波面干涉仪,检验双曲率半径之差为亚毫米量级的轮胎面面形;文中分析了测试原理,给出了测试实例的移相干涉图、双曲率半径测量值及面形波差三维立体图,并分析了测试误差.     

卷积反投影法重建温度场

电子散斑干涉技术是近年发展起来的一门新兴的测量技术,它由光干涉原理测量物理场的密度、温度分布等,这种测量技术是由物理场在不同截面、不同方向上的投影值反求场分布,这非常类似于CT技术。简述二维重建的基本原理,着重介绍卷积反投影重建算法。依此原理,模拟了双高斯分布函数的投影,并由平行束卷积法重建出模拟的温度场。为了指导电子散斑干涉实验,模拟了三种可能实验误差,并分别给出了重建结果。由于电子散斑干涉测量(投影)的方向个数小,提出了双线性滤波算法,使在测量值稀疏的条件下得到较好重建结果。     

Analysis of the fringes visibility generated by a lateral cyclic shear interferometer in the retrieval of the three-dimensional surface information of an object

We report the evaluation of the topography of an object with projected fringes generated with a lateral cyclic shear interferometer (CSI) and we then compare the topography recovery obtained with the proposed method with the one obtained from a coordinate measuring machine (CMM). We also study how the fringes visibility along the z axis affects the retrieval. Finally, we discuss the advantages and drawbacks of this profilometry system.     

Effect of UV radiation on the optical and some structural properties of irregular rayon acetate fibers

This recent study shed demonstration on how the structural parameters changes due exposure to UV radiation and different wavelengths. So this article throws light on the changes of the optical properties and some structural properties due exposure to UV radiation and different wavelengths on irregular rayon acetate fibers. Pluta polarizing interference microscope is used to study the changes for refractive indices and birefringence with different exposure times at three different intensities on irregular rayon acetate fibers. As the principal optical parameters determined, these give an indication of the isotropic refractive index, stress optical coefficient, stress due to UV radiation, optical configuration parameter, segment anisotropy, the number of molecules per unit volume and polarizability of a monomer unit can be obtained. Also by using different wavelengths are given the spectral dispersions, Cauchy's dispersion constants, the resonant wavelength, the oscillation energy, the dispersion energy, the dielectric constant and the dielectric susceptibility for rayon acetate fibers with different wavelengths at room temperatures. Illustrations are given using graphs and microinterferograms.     

基于白光扫描干涉法的光纤折射率分布的测量

提出了一种光纤折射率分布的测量方法,采用白光扫描干涉技术,并在参考镜上构造与光纤样品相同的结构来克服白光相干长度短的限制,优化了光路,提高了干涉条纹间的对比度.采用与白光干涉信号的包络线呈高斯分布的Morlet小波作为小波变换的母小波进行拟合处理,得到光纤与已知折射率的匹配液之间的相对高度.通过计算获得光纤的折射率分布...     

Absolute fringe order calculation using optimised multi-frequency selection in full-field profilometry

We present novel algorithms using multi-frequency analysis for full-field profilometry. The technique provides absolute order of interference in an interferogram. The process is based on an optimisation criterion to utilise the minimum number of projected fringe frequencies to give the largest possible measurement dynamic range. The algorithms presented have been generalised for n frequencies. A set of solutions for three-frequency interferometry is presented that satisfies the optimisation criterion. Results are presented for 3 projected fringe frequencies and we demonstrate by simulation that the approach is indeed optimal. The algorithms given are generic and are equally applicable to any metrological measurement using interferometry.     

Correction of quadratic phase error in two-wavelength digital holographic interferometry using laser diodes

We present the correction of a quadratic phase error in two-wavelength digital holographic interferometry using laser diodes. This phase error arises from numerical reconstructions of wavefronts from digital holograms based on the Fresnel diffraction integral. To correct the quadratic phase error, it is numerically produced by computer on the basis of the theoretical prediction and is subtracted from the phase difference map in two-wavelength digital holographic interferometry. Experimental results show that the method of correction in this paper is useful for two-wavelength digital holographic interferometry using laser diodes.