ELLIPSOMETER

摘要

An ellipsometer according to the present invention is provided with: a non-polarized light beam splitter (18) for branching a reflected light (17) reflected by an object to be measured (16) into first and second light paths (18a, 18b); a light detecting element (19) transmitting a polarized light component in a direction of reference in the reflected light branched into the first light path; and a polarized light beam splitter (20) for separating the reflected light branched into the second light path into polarized light components in directions different from the said reference direction. Then, the lights which have passed through the light detecting element (19) and the polarized light beam splitter (20) are received by respective first, second and third light receivers (21a, 21b,21c). Furthermore, in the method of controlling a coating thickness according to the present invention, first and second ellipsometers (35a, 35b) are provided in the front and in the rear of a coating device (36) arranged along a conveying path of a belt-like plate to be coated (31).