Index profile of radial gradient index lens measured by imaging ellipsometric technique

Abstract

A simple three-intensity imaging ellipsometric technique is proposed for measurement of the refractive index profile (RIP) of a radial gradient index (GRIN) lens. According to our numerical analysis, the improved ellipsometric parameters measured by this method are valid as long as the azimuth deviation of the polarizer is less than 3 degrees. A BK7 glass and a radial GRIN lens were measured. A fairly flat refractive index surface profile was obtained for the glass within a 0.3% error. The on-axis refractive index of the radial GRIN lens and its RIP are well fitted to the specifications provided by the manufacturer. Instead of the refracted-ray method, we provide a reflective and nondestructive measurement technique for measurement of the gradient index of a flat surface.