A comparative study of two generation partial light intensity imager based on liquid crystal

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• 作者：Yuanhe Tang ; ^{ltp1801@163.com} ; Xusan Yang ; Haiyang Gao ; Yong Wu ; Shuiwei Wang ; Xiangang Cao ; Wanli Jia
• 关键词：Imaging system ; Wide dynamic range ; Real time ; Partial light intensity imager ; Liquid crystal
• 刊名：Journal of Quantitative Spectroscopy and Radiative Transfer
• 出版年：2013
• 出版时间：June, 2013
• 年：2013
• 卷：122
• 期：Complete
• 页码：87-96
• 全文大小：1258 K

文摘

Two generations of prototype partial light intensity imager (PLII) based on liquid crystal (LC) are designed and implemented to achieve imaging of objects with strong light illuminations. They can both realize object imaging by controlling each pixel of the LC for a strong light intensity of larger than 2.2¡Á10⁵ lx. There are two ways to control the LC's transmission. One way is to adjust the applied voltage to the LC selected (Sony LCX029AMT) that realizes an adjutable light transmission of 1.28-25.60 % . Another way is to change the angle of polarization of either the polarizer or analyzer and obtain a range of the light transmission of 3.35-17.73 % . The 1st generation of PLII uses a closed feedback loop to control the imaging system with one CCD which requires two frames of image to realize the image gating function. The 2nd generation is an upgraded version that employs two CCDs to improve the real-time imaging performance. While the 1st generation has a lower cost and smaller volume than the 2nd generation does, the 2nd generation has a capability to more easily realize image gating at a video frequency which only requires one single image frame because of the use of two CCDs. The modulate transfer function (MTF) of the two PLII systems using the two transmission control methods is 0.586 and 0.480 respectively.