Laser feedback noise measurement with close-loop servo control for the optical information storage system

摘要

The conventional measuring system of laser feedback noise for an optical pickup was implemented specifically only for laser diodes by using a static optical system. With no close-loop servo control, it is impossible to measure the genuine laser noise distribution of a pickup while operating in an optical drive. With modifying the optical system of a commercial pickup, this study was integrated with precision mechanical design, optical design, servo control design, and opto-electronic signal measurement for providing a dynamic real-time laser feedback noise measurement system. With this system, some experimental results were obtained. The laser feedback noise is responsible to the focusing point within the linear range of an optical pickup head. It has the maximum value while the lens is on the best focus. The central frequency of noise is dependent on the disk rotation speed and the noise level is reducible by increasing the disk rotation speed.