Optical Design and Analysis of the Miniaturized Pickup Head by Employing a MEMS Deformable Reflective Film for High-Density Optical Storage

• Main Authors: Hsin-Hong Lin, 林信宏
• Other Authors: Ian C. Hsu
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/97656949925962679217

碩士 === 國立清華大學 === 原子科學系 === 88 === The accomplishments of this dissertation is designing and implementing a miniaturized optical pickup head that is capable for mass production by employing MEMS technology. The preliminary element designed in the pickup head system is a MEMS deformable reflective film providing a high-frequency servo in the optical storage system. The reflective film performs a perfect spherical mirror at different curvature by deforming its vertex. Hence, the different radius of curvature of the reflective mirror induces a quick change of the focal position of the optical pickup head, and serves as a focusing servo system. By controlling the deformable parameters, the servo system affords high frequency response that is capable for high speed optical storage.. We work out three designs of optical system: (A) replacing the folder mirror by the deformable film; (B) inserting a plate beam splitter into the optical path; (C) inserting a cube beam splitter into the optical path. The three designs were simulated for pickup head of optical storage system. Utilizing the ray tracing methods based on geometric optics retrieves the variations of the focal position corresponding to the displacements of film’s vertex. Next, the optical software-ZEMAX- simulates the profiles of the focal spot of the designed optical systems, and exam the diffraction-limited property of the focal spot. In conclusion, the changes of focal position of the three designs are adequate for a focus servo of the variations of the disk substrate. The quality of focal spot is appropriate for the pickup head system in the design (B). and (C). However, the focal spot cannot perform the diffraction-limited quality in the design (A).