Patent ID: 7570362

Claim:
An optical measurement apparatus using total reflection, including a light source, a measurement optical system, and a light detector, wherein the measurement optical system is an infinity-corrected positive lens formed of an optical member having a planar surface orthogonal to an optical axis of the measurement optical system at a front focal position; wherein one side of the optical axis of the measurement optical system is used as a projection optical system configured to radiate measurement light onto a specimen, and another side is used as a photometric optical system configured to acquire reflected light from the specimen; wherein the light source is disposed at an entrance pupil position on the projection optical system side or at a position conjugate to the entrance pupil position and moves in an entrance pupil plane or in a plane conjugate to the entrance pupil position, along a straight line orthogonal to the optical axis, while a distance from the optical axis is detected; and wherein the light detector is disposed at an exit pupil position on the photometric optical system side or at a position conjugate to the exit pupil position; the optical-measurement apparatus comprising a light-source changing unit configured to change the position or shape of the light source.