Optical design for the compact area-type

• Main Authors: PEN,CHUN-CHI, 潘俊吉
• Other Authors: Senfar Wen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/25935474742600772975

碩士 === 中華大學 === 電機工程學系(所) === 97 === Traditional optical fingerprint reader uses a right-angled prism and an imaging lens. This thesis studies the optical design of an improved fingerprint reader which uses a spherical lens on the output side of a prism and a symmetrical aspheric lens as the imaging lens. An LED light source normally illuminates the hypotenuse side of the prism and the finger pressed on the bottom side of the prism. The results show the distortion has been improved. We follow the design processes: (1) calculating first-order optical structure parameters, (2) using ZEMAX optical software to optimize the system, (3) using Monte Carlo method to analyze tolerance and obtain yield rate. The systems with 60mm, 65mm, and 70mm total lengths are designed. Considering spot size and taking RMS diameter as a metric, we have 100% probability for the three systems that their spot sizes are within detector pixel size. Considering MTF, we have more than 98% probability for the 65mm and 70mm systems that their MTFs meet design requirements. The probability for the 60mm system that the MTF meets design requirements is only 80%. The main factor influence yield rate is distortion. The yield rates are 44%, 76%, and 95% for The systems with 60mm, 65mm, and 70mm total lengths, respectively.