激光散斑干涉测量液体折射率的误差分析与改进  

Error Analysis and Improvement of Liquid Refractive Index Measurement Using Laser Speckle Interferometry

作　　者：罗劲明 古家玮 李俊豪 周柔燕 邓定南 Luo Jinming;Gu Jiawei;Li Junhao;Zhou Rouyan;Deng Dingnan(College of Physics and Electronic Engineering,Jiaying University,Meizhou,Guangdong 514015,China)

机构地区：[1]嘉应学院物理与电子工程学院,广东梅州514015

出　　处：《激光与光电子学进展》2022年第5期156-162,共7页Laser & Optoelectronics Progress

基　　金：广东省2018年高等教育教学改革项目(542);广东省基础与应用基础研究基金项目(2020A1515110283)。

摘　　要：根据透明介质的光学折射特性,分析了内标法的测量误差,提出了一种激光散斑干涉测量液体折射率的改进方法,设计了一种由完全相同的两个长方体槽组成的双槽结构,其中一槽装有待测透明液体,并以此搭建了一套像面散斑光学测量系统,双槽结构则置于成像透镜和CCD相机之间。首先调节双槽至平行且垂直于光轴放置,利用CCD相机采集一张散斑图,接着调节双槽的夹角使其左右对称地偏转微小角度放置,此时再采集一张散斑图,然后采用数字散斑相关方法进行处理得到变化前后的散斑面内偏移量,最后理论计算出透明液体的折射率。利用这一方法测量了水和乙醇的折射率,并与内标法相比较,结果表明改进方法具有误差小、精度高的特点。According to the optical refraction characteristic of transparent medium,the measurement error of internal standard method is analyzed,and then an improved method of liquid refractive index measurement using laser speckle interferometry is proposed.This paper designs a double-groove structure composed of two identical rectangular grooves with one of the grooves filled with the measured liquid,and then an image speckle optical measurement system has been built,while the double-groove structure is placed between the imaging lens and CCD camera.First,adjusting the two grooves to be parallel and perpendicular to the optical axis,one speckle pattern is collected by CCD camera.Then adjusting the included angle of two grooves to make them symmetrically deflect to a small angle,another speckle pattern is collected.After that,a speckle in-plane displacement before and after the change is obtained by processing the above two speckle patterns using the digital speckle correlation method,and finally the refractive index of transparent liquid can be calculated theoretically.According to the above method,the refractive indices of water and ethanol are measured,and the results show that this improved method has the advantages of small error and high accuracy,compared with internal standard method.

关 键 词：测量 散斑干涉 折射率 数字散斑相关 内标法 

分 类 号：O438.1[机械工程—光学工程]