Shapiro and Shapiro
Apparatus for measuring thickness of plate-shaped article
 An apparatus for measuring the thickness of a plate-shaped article with a substantially rectangular lateral face, comprises a measuring optical system including a light-emitting unit for emitting a measuring light beam along an optical axis in a predetermined plane, and a light-receiving unit provided on said optical axis and adapted to generate an output signal corresponding to the amount of detected measuring light, support system for supporting the article in such a manner that the article is substantially parallel to the predetermined plane and the measuring light enters obliquely the lateral face of the article, relative movement unit for moving, in a direction crossing said predetermined plane, either of said article and the measuring light relative to the other, and determination unit for determining the thickness of the article, based on the output signal of the measuring optical system and the amount of movement by the relative movement unit. 
Nikon Corporation
G
G01B
inventional
Kazuhiro Kinya
Takaoka Kato