Stress-induced Self-assembly of a Fresnel Lens for an Optical Pick-up Head

• Main Authors: Yi-Hsien Chen, 陳依纖
• Other Authors: Yi Chiu
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/3x37q7

碩士 === 國立交通大學 === 電機與控制工程系所 === 93 === Because of the progress of information technology (IT), the need for high speed and high density data storage has become increasingly important. The optical data storage system is one of the important devices for this need. The requirement of miniaturization and lightness pushes the development of more miniature and lighter optical data storage system. Micro Optical Electro Mechanical System (MOEMS) technology is one of methods to reach this target. If self-assembly of the MOEMS devices is realizable, it will make the technology an easier and cheaper way to produce the miniaturized pick-up head. It is important to exploit self-assembly mechanisms to assemble optical systems automatically. Until now, several methods have been developed to assemble the upright components, but extra electricity, heat or fabrication processing is needed. In this study, stress-induced beams are used to accomplish the self-assembly function to assemble a Fresnel lens. The tensile stress comes from the last metal layer in the process. The lens is the focusing component in a pick-up head. There are two kinds of lenses. One is diffractive lens, and the other is refractive. Each has its own advantage in optics. Here the diffractive lens – Fresnel lens is used because the Fresnel lens has several advantages such as much larger aperture, thin and light. The advantage of lightness makes it easier to flip up the lens structure by the stress-induced beam in this system. Different materials have been used to manufacture Fresnel lens. In this study, the thickness photoresist SU8 is adopted because the SU-8 has low absorption at blue laser wavelength.