Focus initialization system for optical recording

Focus operation for an optical disk device

Focus operation for an optical disk device

Focus servo control device for optical disks having servo offset

Focus servo control system for automatically adjusting a relativ

Focus servo device for detecting and compensating for disk abnor

Focus servo device for use in an optical information read-out de

Focus servo device of a system for reading out recorded informat

Focus servo loop correction

Focus servo loop off-set compensation

Focus servo system having object lens protection circuit for an

Focus-servo correction utilizing storage of detected focus error

Focused-spot-position detection device for optical information r

Focusing control circuitry for an optical memory system

Focusing detection apparatus

Focusing error detection apparatus

Focusing optical head movable radially by a carriage

Focusing system for video disc player

Focussing error detection device for use in optical disk type re

Focussing lens servo driving device for optical information read