Please use this identifier to cite or link to this item:
標題: 光學頭聚焦誤差對雷射反饋雜訊的影響之研究
Study of the laser feedback noise corresponding to the focusing error of optical pickup heads
作者: 許德偉
Shiu, De-Wei
關鍵字: feedback noise;反饋雜訊;focusing servo control;laser diode;optical pickup head;quarter wave plate;relative intensity noise;聚焦伺服控制;雷射二極體;光學讀取頭;四分之一波長片;相對強度雜訊
出版社: 機械工程學系
摘 要

The conventional measuring system of laser feedback noise was implemented specifically for laser diodes by using a static optical system. (not by a concrete optical head operating under the disk) Without the servo close-loop control, it is impossible to measure the genuine laser noise distribution of a pickup while operating in an optical drive. Furthermore, it is infeasible to obtain the information of laser noise corresponding to the focusing error and rotation speed. Therefore, it is hard to realize the relation between the read-write signal quality and the laser noise of optical heads.
This study was integrated with precision mechanical design, optical system design, servo control design, and opto-electronic signal measurement. With modifying the optical system of a commercial pickup for our main system, the servo controller using a digital signal processor was designed to drive the actuator for the focusing of the objective lens. It provided a dynamic model in real time for measuring the laser feedback noise distribution of a pickup corresponding to the focusing error, rotation speed, and temperature variation under operation.
The experimental results show that the laser feedback noise is responsible to the focusing point within the linear range of an optical pickup head. The noise level is sensitive to the temperature variation and its central frequency is dependent on the disk rotation speed. Besides, this study also verified that the laser feedback noise is reducible by inserting a quarter-wave-plate in the optical system. It is useful for achieving the noise immunity.
Appears in Collections:機械工程學系所

Show full item record

Google ScholarTM


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.