Measurement of refractive index distribution using micro-lens array based on total internal reflection

Abstract

We present a method based on total internal reflection (TIR) phenomenon for measuring the refractive index (RI) distribution with high-precision. In the field of RI measurement, the method based on TIR phenomenon is usually used to detect the average RI of the sample under tested, but unable to get the detail of RI distribution. We present a new method, using the micro-lens array to split the beam of light and divide the testing surface into a certain number of tiny detection areas. With the detector of area CCD camera, each pixel collects the reflected light from each tiny detection area respectively. By analyzing the reflectivity to each tiny detection area, we can get RI information of each tiny area. Through theoretical calculation and the actual scaling, the RI value of each spot is obtained. After collecting the RI of each tiny area, we can obtain the RI distribution.