基于等厚干涉原理的液体折射率测量方法

Measurement of Refractive Index of Liquid by the Equal Thickness Interference

将空气劈尖的等厚干涉原理与CCD图像处理技术相结合,提出了一种对透明液体折射率进行自动测量的新方法.利用一元线性回归方法对CCD的像元序号与所接收到的干涉条纹光强极大值序号之间的线性关系进行拟合,进而由拟合系数与待测液体折射率之间的关系计算出液体的折射率.为了在测量中获得理想的干涉条纹图,对影响干涉条纹图像质量的主要因素进行了详细分析,并给出了具体的背景光消除方法.实验以水为测量对象,测量结果表明,新的测量方法是可行的,测量结果的相对误差为0.09%,另外,新的背景光消除方法,对其他光学实验中如何获得清晰的干涉条纹,也具有一定的参考价值.

A technique for automatic measurement of the refractive index of liquid was proposed. The approach based on the principle of the equal thickness interference of air wedge and charge coupled device （CCD） image processing technique. The unitary linearity regress method was used to fit the relation between the serial number of the CCD pixels and the serial number of the intensity maximum of interference fringes, and the regress coefficients were used to compute the refractive index of liquid. Some factors affecting the quality of fringe patterns were taken into account and perfect fringe patterns were obtained by removing background light. The experiment result proves the feasibility of the new method. The relative error of the refractive index of water is 0.09%. In order to obtain clear interference fringes in other optical experiment, the new method of removing background light is worthy to be considered.