SHEARING INTERFEROMETER, REFRACTION INDEX DISTRIBUTION MEASURING DEVICE PROVIDED WITH THE INTERFEROMETER AND MEASURING METHOD FOR REFRACTION INDEX DISTRIBUTION

摘要

PROBLEM TO BE SOLVED: To provide a method for reducing ghost light and improving S/N ratio in a shearing interferometer. ;SOLUTION: For a shearing interferometer splitting detected wave of coherent light transmitted into a detected body into 2 light fluxes, giving the shift in vertical direction to the light axis between the two light fluxes and overlapping, two slab plates 45 and 47 arranged facing to each other via a small gap d are provided. The surfaces 47b and 45a among 4 surfaces 45a, 45b, 47a and 47b which those 2 slab plates 45 and 47 have are made parallel and at least a single surface among 47a or 45b is made non-parallel to the 2 parallel surfaces 47b and 45a. By this, ghost light is separated from the detected wave and a ghostless measurement becomes possible.;COPYRIGHT: (C)2000,JPO