Improvement Of Focusing And Tracking Servos In Optical Disk Memory

In a single beam read-write optical head, an astigmatic method using a cylindrical lens and a push-pull method are adopted for focusing and tracking error sensing, respectively. The disturbances for the servo sensing signals when the optical head records and reads along a pregrooved track, which has the depth of X/8 and is locally intermittent for address code, are compensated by signal processing technology.