Shapiro and Shapiro
Optical alignment apparatus
 An optical alignment apparatus with an image-forming optical system for forming an image of an object by means of a light beam and detection means for detecting the position of the object image comprises a collimator lens group for converting the beam coming from said object and having the principal rays intersecting the optical axis into a collimated beam and a condenser lens group for condensing the collimated beam. The condenser lens is so disposed that its optical axis is substantially coincident with the principal ray of the collimated beam from the collimator lens group. In the optical alignment apparatus, the principal rays of the beam passed through the condenser lens group perpendicularly fall on the focal plane of the condenser lens group, and after passing through the condenser lens group, the principal rays pass through the central area of every optical element. 
Nippon Kogaku K. K.
G
G03F
inventional
Kazumasa Kinya
Endo Kato