Patent ID: 6381015
Filing Date: 2002-04-30
Classification: A61B,G01J,G01N

Abstract:
An inspection apparatus using an optical interferometer comprising splitting and combining means for splitting light from a light source into incident light irradiated on a sample and a reference light and combining signal light which is light scattered or reflected by the sample and the reference light, a modulator for subjecting any of the incident light, the reference light and the signal light to phase modulation and a photo detector for detecting light combined by the splitting and combining means, said inspection apparatus further comprising:detecting means for separating and detecting amplitudes of first signal components having frequencies of multiples of odd numbers of a fundamental modulation frequency of the modulator and amplitudes of second signal components having frequencies of multiples of even numbers of the fundamental modulation frequency; and means for calculating an intensity of the signal light by using the amplitudes of the first and the second signal components.