FIELD: automatic control. SUBSTANCE: movable slip member displaces in axial direction within fixed member under action of focusing drive accoirding to signals arriving from control unit. Interference pattern is formed across photodetectors of photodetector unit; photodetectors are grouped and connected in phase opposition. Control unit performs digital control of focusing drive. EFFECT: improved design. 12 dwg
Authors
Dates
1995-05-20—Published
1991-04-23—Filed