可调焦自适应光学扫描激光眼底成像系统设计

Optical Design of Adaptive Optics Scanning Laser Ophthalmoscope with Adjustable Focus

自适应光学扫描激光眼底成像系统研究是当前研究的一个热点。利用Badal系统、变形镜和夏克-哈特曼波前传感器设计了一种可调焦的自适应光学激光扫描眼底成像系统,通过视标引导,调节Badal系统中的透镜间距,实现人眼低阶像差校正。根据系统调焦及工作原理,分析了Badal系统最佳参数,并对系统参数进行设计,采用Zemax光学软件对系统进行仿真及优化。仿真结果表明,设计的系统点列图光斑小于衍射极限,各屈光度斯特列尔比值均大于0.8,甚至低屈光度下的斯特列尔比可达0.95,不同屈光度下各视场调制传递函数(MTF)曲线接近衍射极限,正常人眼视网膜面上系统理论分辨率约为2.29μm,接近衍射极限分辨率(2.11μm),能够对-6～6m-1屈光不正的人群实现眼底视网膜清晰成像。

Adaptive optics scanning laser ophthalmoscopy(AOSLO)has gained increased research attention over the past few decades.This study proposes a focus-adjustable AOSLO that uses a novel optical design comprising a Badal system,a deformable mirror,and a Shack-Hartmann wavefront sensor.This design corrects the low-order aberration of the human eye by setting a target and adjusting the distance between lenses in the Badal system.The optimum parameters of the Badal system based on the focusing and working principle of the system are analyzed;then,the system is simulated and optimized by Zemax software.Simulation results show that the spot size of the proposed system is smaller than the diffraction limit in the spot diagram.The Strehl ratio of any diopter is more than 0.8 and approaches as high as 0.95 for a low diopter.The modulation transfer function of every field approaches the diffraction limit.Moreover,the theoretical resolution in the normal human retina of this system(2.29μm)is in a close range to the diffraction-limit resolution of the proposed system(2.11μm).The proposed system can achieve a clear imaging of the human retina for people with a diopter from-6 m-1 to+6 m-1.