INSPECTION APPARATUS USING OPTICAL INTERFEROMETER

摘要

An inspection apparatus uses an optical interferometer comprising optical branching/multiplexing means (3) for branching light from a light source (1) into an irradiating light (41) irradiating a sample and a reference light (40) and multiplexing a signal light, which is scattered or reflected by a sample (7, 42), with the reference light, a modulator (4, 5, 10) for phase modulation of the reference light, and a photodetector (9) for detecting light, multiplexed by the optical branching/multiplexing means (3). The inspection apparatus uses the optical interferometer further comprising first means (12-1) for detecting an amplitude of a first signal component which is included in a signal from the photodetector (9) and has a frequency odd multiples of a basic modulation frequency of the modulator, second means (12-2) for separatingly detecting an amplitude of a second signal component which is included in the signal from the photodetector and has a frequency even multiples of the basic modulating frequency of the modulator, and means (14) for finding an intensity of the signal light using amplitudes of the first and second signal components, the optical interferometer providing a high signal stability and a high signal versus noise ratio. In measurement of a sample such as an organism, in which light is largely scattered or attenuated, it is possible to highly accurately measure refractive indexes and distribution of absorption coefficients up to a region of large depth.