基于光路补偿的数字全息干涉法测量液相扩散系数

Measurement of liquid diffusion coefficient by digital holographic interferometry based on optical path compensation

液相扩散系数的测量在工业生产中有着重要的作用.本文基于光路补偿方法,利用Mach-Zehnder干涉光路测量液相扩散系数.激光全息干涉光路的物光和参考光分别经过扩散槽和补偿槽,当扩散槽内待测液体扩散时,干涉图样会发生变化,通过条纹判别法,对两张不同时刻的干涉图样进行图像处理即可得到扩散系数.图像处理时需要对图像进行小波去噪和频域滤波,将滤波后不同时刻干涉图样叠加后,用DCT变换的最小二乘相位展开算法,对叠加图进行相位离散得到相位变化图,通过读取其浓度变化最大值之间的距离即可求出液相扩散系数.

The measurement of liquid diffusion coefficient plays an important role in industrial production.In this paper,based on the optical path compensation method,the Mach-Zehnder interferometric optical path is used to measure the liquid diffusion coefficient.The object light and the reference light of a laser holographic interference path passed through the diffusion groove and the compensation groove respectively.When the liquid to be measured diffused in the diffusion groove,the interference pattern would change.The diffusion coefficient can be obtained by image processing of two interference patterns at different times by fringe discrimination method.Wavelet deposing and frequency-domain filtering are required for image processing.After the interference patterns at different times are superimposed after filtering,the phase changes are obtained by phase discretization of the superimposed images using the least square phase unwrapping algorithm of DCT transform.The liquid phase diffusion coefficient can be obtained by reading the distance between the maximum concentration changes.