开环双脉冲液晶自适应光学视网膜成像系统

为了获得高分辨率视网膜图像，利用液晶空间光调制器作为波前校正器建立了一套开环液晶自适应光学视网膜成像系统。与闭环模式相比，采用开环模式后，系统的能量利用率提高了1倍。系统采用双脉冲照明方式，以减少人眼曝光量，保护人眼安全。在照明光学系统中加入了大小视场切换装置使成像视场由之前的0.8°增至1.7°。同时优化了系统的时序控制流程，对人眼像差连续校正的同时快速调节成像相机的前后位置至最佳像面。对于开环模式对动态人眼像差的校正精度进行了测量，实验测得，经开环校正后，残差波面的均方根值约为0.09λ；相应的斯特雷尔(Strehl)比高于0.70，系统分辨率接近光学衍射极限的分辨率。对两名志愿者进行了实验，获得了清晰的眼底视网膜细胞图像。

Liquid Crystal Adaptive Optics System for Retinal Imaging Operated on Open-Loop and Double-Pulse Mode

Using the liquid crystal spatial light modulator as the wavefront compensator, an open-loop adaptive optics system for retinal imaging is developed. Compared with the closed-loop liquid crystal adaptive optics system, the energy efficiency is doubled. The fundus is illuminated twice by two laser pulses throughout a single correction loop, which will be much safer for the human eye. A modified mechanical shutter is incorporated in the illumination channel to change the imaging field, and the field of view is thus increased from 0.8° to 1.7°. The timing sequence is optimized, and the continuous correction is performed. Meanwhile, the imaging camera is adjusted to achieve the best image plane. The residual wavefront error after open-loop correction is approximately equal to 0.09λ, and the Strehl ratio is bigger than 0.70. It is a nearly diffraction limited system. The clear photoreceptor images are obtained through open-loop correction.