Patent ID: 6597006
Filing Date: 2003-07-22
Classification: G01B

Abstract:
A system configured to assess a height of a specimen during use, comprising:an illumination system configured to direct a first and a second beam of light to a surface of the specimen at substantially opposite azimuth angles and at substantially equal angles of incidence during use such that the first and second beams of light illuminate substantially the same area of the surface of the specimen; a collection system configured to collect the first beam of light specularly reflected from the surface of the specimen and to collect the second beam of light specularly reflected from the surface of the specimen during use; first and second detectors, wherein the first detector is configured to generate an output signal responsive to the collected first beam of light, and wherein the second detector is configured to generate an output signal responsive to the collected second beam of light during use; and a device configured to receive the output signals from the first and second detectors during use and to generate a comparison signal from the output signals during use, wherein the comparison signal is responsive to the height of the specimen.