To achieve the high accuracy correction of the distorted wavefront
dynamic phase response characteristic between different grey levels of liquid crystal wavefront correctors (LC WFCs) was investigated. First
a scheme was given to measure the response time and phase modulation of the LC WFC. Then
the fall and rise time of a LC WFC were measured between 0 and 255 grey levels. The results indicate the rise and fall time are 7 ms and 11 ms respectively. To assure the correction accuracy
the phase modulation curves were cut off with error of
/10 (
=633 nm) and then the rise and fall time were reduced to 4 ms and 6.8 ms respectively. At last
the dynamic response time
which is produced with every other grey levels go up to 255 grey level and the reverse process
was measured. The measured results show that the rise and fall time of the grey levels vary at the range of 2~5.2 ms and 3.7~8.7 ms respectively. Simultaneously
the switching time between the grey level of 150 and 255 is shortest for both of the rise and fall time
and the response time is longest for the grey levels which is adjacent to 255 grey level. Furthermore
the response time of the grey levels nearby 255 grey level is larger than the response time between 0 and 255 grey level. Therefore
to assure the accurate correction of the wavefront
the response time of the LC WFC should be selected with the longest switch time among the grey levels which is adjacent to 255 grey level.
关键词
Keywords
references
Love G. Wave-front correction and production of Zernike modes with a liquid-crystal spatial light modulato [J]. Appl. Opt., 1997, 36(7):1517-1524.[2] Seratis S, Stockley J. Advances in liquid crystal based devices for wavefront control and beamsteering [J]. Proc. SPIE, 2005, 5894: 58940K-1-58940K-13.[3] Cao Z L, MU Q Q, HU L F, et al. An achromatic system for twisted alignment liquid crystal wavefront correct [J]. Appl. Opt., 2008, 47(8):1020-1024.[4] HU L F, Xuan L, Liu Y J, et al. Phase-only liquid crystal spatial light modulator for wavefront correction with high precision [J]. Opt. Express, 2004, 12(26):6403-6409.[5] Restino S R, Dayton D, BrowneS, et al. On the use of dual frequency nematic material for adaptive optics systems: first results of a closed -loop experiment [J]. Opt. Express, 2000, 6(1):2-6.[6] 陈浩, 宣丽,胡立发,等. 望远镜的紧凑型闭环液晶自适应光学系统设计 [J]. 液晶与显示, 2010, 25(3):379-385.[7] 李鹏飞, 许金凯,胡立发,等. 人眼像差校正仪成像CCD随动控制的设计与实现 [J]. 液晶与显示, 2010, 25(5):733-737.[8] Femando V M, Pablo A. Phasor averaging for wavefront correction with liquid crystal spatial light modulators [J]. Optics Communications,1998, 152(4):233-238.[9] 曹召良, 穆全全,胡立发,等. 液晶波前校正器位相调制非线性及闭环校正研究 [J]. 液晶与显示, 2008, 23(2):157-162.[10] 李大禹,胡立发,穆全全,等. CUDA架构下的液晶自适应波面数值解析 [J]. 光学 精密工程, 2010, 18(4):848-854.[11] Cao Z L, Mu Q Q, Hu L F, et al. Correction of horizontal turbulence with nematic liquid crystal wavefront corrector [J]. Opt. Express, 2008, 16(10):7006-7013.[12] Cao Z L, Xuan L, Hu L F, et al. Effects of the space-bandwidth product on the liquid-crystal kinoform [J]. Opt. Express, 2005, 13(14):5186-5191.[13] Cao Z L, Mu Q Q, Hu L F, et al. Improve the loop frequency of liquid crystal adaptive optics by concurrent control technique [J]. Optics Communications, 2010, 283(6):946-950.[14] 刘永军,宣丽,胡立发,等. 高精度纯相位液晶空间光调制器的研究 [J]. 光学学报, 2005, 25(12):1682-1686.[15] 姜宝光,穆全全,曹召良,等. 液晶空间光调制器对真实人眼畸变波前的校正 [J]. 光学 精密工程, 2009, 17(11):2651-2656.