Frishauf, Holtz, Goodman and Woodward
System for focusing an optical head onto a flat surface
 A system for focusing an optical head onto a flat surface has a mechanism for moving the optical head in the direction of the optical axis of the head and a mechanism for moving an objective lens in the optical head in the direction of the optical axis of the lens. A laser beam projected from the objective lens of the optical head is reflected on the flat surface, is reflected on the beam splitter, and is introduced into a detector unit. The detector unit thus generates a focusing signal having a level responsive to the distance between the objective lens and the surface. The optical head is lowered by the mechanism for moving the optical head in accordance with the focusing signal when it passes a predetermined point, and is operated to locate the focal point of the objective lens on the surface. Thereafter, the mechanism for moving the optical head becomes inoperative, and the mechanism for moving the objective lens is operated. This mechanism operates in accordance with the focusing signal and locates the focal point of the objective lens always on the surface. 
Olympus Optical Co., Ltd.
G G G
G11B G11B G02B
additional inventional inventional
Shoji Ken Hiroshi Masaharu Kunio Kiichi
Yoshikawa Ohshima Kodama Sakamoto Yamamiya Kato