Determining the refractive index profile of micro-optical elements using transflective digitalholographic microscopy

Abstract

This study proposes a novel method for directly measuring the spatial distribution of therefractive index of transparent or semi-transparent micro-optical elements using digitalholographic microscopy, which involves transmission and reflection architectures. Theproposed transflective digital holographic microscope system simultaneously records boththe transmitted and the reflected waves from the micro-optical element and thennumerically reconstructs the phase information and refractive index profile. No priorknowledge of the thickness and curvature of the element to be measured is required. In thisstudy, the spatial refractive index profiles of a microlens array and a gradient index lens aredemonstrated experimentally. Unlike the conventional scanning refractive ray method, theproposed method supports the rapid full-field nondestructive measurement and directobservation of the spatial index variation and structure of micro-optical elements.