Patent ID: 6741362
Filing Date: 2004-05-25
Classification: G01N

Abstract:
A method for determining a three-dimensional refractive gradient index of an object, comprising an optical material, in an interferometric refractive index measurement system, comprising:a. locating the object in a normal orientation in the interferometric refractive index measurement system along a first axis between a reference surface and a retro-mirror surface, whereby a second axis and a third axis are normal to each other and normal to said first axis; b. measuring a first through forth phase differences, respectively, between a reference wavefront and a wavefront reflected from a first surface of the object, said reference wavefront and a wavefront reflected from a second surface of the object, said reference wavefront and a wavefront reflected from a retro-mirror through the object, and said reference wavefront and a wavefront reflected from said retro-mirror surface; c. determining a first through third two-dimensional surface deformations of said reference surface, said first surface, and said second surface, and said retro-mirror surface, respectively, based on said first through forth phase differences; d. determining an average two-dimensional inhomogeneity of the object based on said first through forth phase difference measurements; e. determining a plurality of coefficients of approximation (Ai) of the object based on said average two-dimensional inhomogeneity; f. performing a plurality of rotations of the object by angles about said second axis and said third axis; g. measuring a further phase difference between said reference wavefront and a wavefront reflected from said retro-mirror for each one of said plurality of rotations; h. determining a plurality of coefficients of approximation (Aij) of the object based on said two-dimensional surface deformations and said phase difference measurements.