双波长大口径液晶光弹性测量仪研制  

Development of Dual-Wavelength, Large-Diameter, Liquid-Crystal Photoelasticity-Measuring Instrument

作　　者：陈昱志 邢童璐 林强[1] 刘诚[1,2] 朱健强 Chen Yuzhi;Xing Tonglu;Lin Qiang;Liu Cheng;Zhu Jianqiang(Key Laboratory of High Power Laser and Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海光学精密机械研究所高功率激光物理联合实验室,上海201800 [2]中国科学院大学,北京100049

出　　处：《中国激光》2024年第13期133-142,共10页Chinese Journal of Lasers

基　　金：国家自然科学基金(61827816);工业和信息化部项目(TC220H05L)。

摘　　要：提出了一种基于双波长椭圆偏振光测量光弹性应力的方法,采集两种相近波长照明下、特殊液晶旋光角度下透过待测样品的光强分布图像,对其进行一系列计算处理,得到待测样品的应力分布。利用双波长LED和液晶旋光板等先进光源和先进光调控器件,发明了一个可以测量样品中应力分布的光学仪器。进行了相关的实验测量,并与传统的六步相移方法做了实验对比验证了该方法的有效性,相对误差达到2.85%。且所研究的光弹性液晶测量仪结构简单、操作快速,不需要复杂的机械旋转等手动调控。仪器分辨率达到0.25 mm,符合光弹性测量标准。Objective One of the main technical difficulties in the measurement of large differential dimensions and oversized components using optical elastometers is that only spatial scanning and splicing measurements are realizable,which significantly reduces the measurement accuracy.According to the basic principle of liquid-crystal displays (LCDs),liquid-crystal panels can be modulated rapidly under the action of the applied voltage and the pixel-by-pixel light polarization state.Moreover,technological advancement has enabled the size of a single liquid-crystal panel to reach 10 m~2 or larger.If the liquid-crystal panel can be used as a light source for photoelasticity instruments,then high-speed rail windshields and float-glass assembly lines on flat glass and other large-sized components can be inspected online at high speeds.Thus,the speculative large-diameter measurement problems inherent in existing photoelasticity-measuring instruments can be overcome.However,most liquid-crystal panels emitting elliptically polarized light cannot be used easily to obtain the ideal circularly polarized light,which implies that the existing circularly polarized light cannot be used directly.Therefore,a measurement method for elliptical-light illumination must be developed.Methods Using an LCD instead of a quarter-wave plate enabled the system used in this study to automatically adjust the form of elliptically polarized light,thus significantly reducing costs and providing a theoretical basis for large-sample measurements.The illumination involved two lights of similar wavelengths,and the LCD directed both forms of elliptically polarized light onto the sample vertically.Subsequently,a CCD was used to record an image of a linearly polarized light modulated by a quarter-wave plate and polarizer.Finally,the principal-stress difference was accurately determined from a set of 12 phase-shifted images using the developed algorithm.Results and Discussions To verify the comprehensive performance of the developed instrument,we used a classic

关 键 词：光弹性测量 应力 液晶 椭圆偏振光 

分 类 号：O436[机械工程—光学工程]