液晶校正器漏光对闭环校正波前探测准确度的影响

Effect of Parasitic light of Liquid Crystal Wavefront Correctors on the Accuracy of Wavefront Sensing in the Closed Loop Process

研究了液晶分子排列对哈特曼波前探测器探测及闭环校正的影响.首先分析了分子排列对液晶校正器产生漏光强度的影响.详细探讨了在闭环校正过程中漏光对波前探测及校正准确度影响,当漏光比为40%时,产生的探测偏离误差为0.4;对于8%的漏光比,探测误差仅为0.08,可以忽略.最后分别做了扭曲和平行排列液晶校正器对静态畸变的闭环校正实验.对于漏光比为40%的扭曲液晶校正器,校正前后的PV和RMS值分别为:1.11μm、0.25μm和1.08μm、0.24μm,说明漏光对闭环校正产生了严重影响.对于漏光比为8%的平行排列液晶校正器,通过闭环校正,波前的PV和RMS分别从1.58m和0.22m降到0.095m和0.03m,同时获得清晰的光纤束的像.结果表明,如果能够控制液晶波前校正器的漏光占总光强的比在8%以下,则可以获得高校正准确度.

Effects of liquid crystal molecules alignment on the detection of Shack-Hartmann wavefront sensor and closed loop correction are investigated.The effect of molecule alignment on the intensity of parasitic light is analyzed.The effect of parasitic light on detection and correction accuracy was specially discussed among the closed loop correction. With the ratio of parasitic light of 40%, the detection deviation error is 0.4｜ while the ratio of parasitic light is 8%, the deviation error just have 0.08, and it may be neglected. And the closed loop correction of static distortion was individually done with twisted and parallel alignment LC WFC. To the twisted alignment, PV and RMS were changed from 1.11 μm and 0.25 μm to 1.08 μm and 0.24 μm. It indicates that the parasitic light causes the serious effect on the closed loop correction. For parallel alignment, with the closed loop correction, PV and RMS are reduced from 1.58 μm and 0.22 μm to 0.095 μm and 0.03 μm respectively, and the resolvable image of the fiber bundle is also achieved. The results show that, if the intensity of parasitic light is lower than 8%, high correction accuracy can be obtained.