Interlinked Tracking Servo Technology

The well known push-pull method has a problem in tracking offset caused by deviation of the beam axis and disk inclination. The tracking offset degrades the tracking servo performance and the track following range is conventionally restricted to about ±50pm. To solve this problem and enlarge the track following range, we have developed a new tracking servo technology which uses two actuators interlinked by servos. This method completely eliminates the deviation of the beam axis and enables a track following range of ±400 μm.