Diffractive Optical Element Design and Analysis for Miniature MEMS DVD Pickup

• Main Authors: Wen-Jie Chen, 陳文傑
• Other Authors: Cheng-Huan Chen
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/05193301778108498635

碩士 === 國立臺灣科技大學 === 電子工程系 === 92 === In this thesis, diffractive optical elements (DOEs) are designed to implement optical functions of collimation and beam splitting for a MEMS-type DVD pickup at 405nm wavelength and the efficiency of DOEs is analyzed with Matlab. A Fresnel lens with the first, second, and third zone quantized as eight, four, two phase levels, respectively is presented and the estimate of its efficiency can reach 92%. Moreover, the majority of the beam splitters for three beam tracking in commercial DVD pickup employ binary phase gratings. A 1-to-3 beam splitter with equal-side triangular saw-tooth profile has been investigated as an improved solution and the geometrical size of the profile has been optimized for several desired energy ratio. A table of optimal phase level for a given energy ratio and desired minimum required total efficiency with the consideration of fabrication cost has also been provided for a reference in system design.