运用非球面光学理论,设计了一款基于Gullstrand-Le Grand眼模型的便携式非球面眼底荧光相机。该相机根据滤光片选择原则,选用Nikon公司的B-2A滤光组合作为滤光系统进行光谱滤光;为避免角膜中心较大曲率引起的杂散光,采用环形光阑和共轴式照明相结合的照明方式实现眼底均匀照明;摄影系统中引入眼模型结构,综合校正了人眼及系统的像差,实现了全视场20×106pixel的高清晰成像。该摄影系统包含有2个非球面结构,使系统由9片镜结构简化为7片镜结构。实验结果表明,该相机具有较大的调节能力,对-12~+12m-1的人眼普遍适用,其视场角为30°,像面成像分辨率为120lp/mm,畸变值〈3.9%。非球面光学元件的使用,有效地简化了系统,减小了系统体积和重量,提高了成像质量。
By use of aspheric optical elements,a portable Fundus Fluorescein Angiography(FFA) camera is designed based on Gullstrand-Le Grand eye model.According to the principle of selecting filter,a B-2A filter combination from Nikon is used as the filter system to filter spectrum in this design,and the coaxial illumination system combined with an annular stop is designed to remove the stray light caused by a cornea to light the eyeground uniformly.An eye model is used in the design of photographic system to correct comprehensive aberrations from both the optical systems of human eye and the camera and to realize a high definition image with 2 mega pixels in all fields of view.The photographic system of the camera includes two aspheric surfaces,and it reduces the system from 9 lenses to 7 lenses.The result shows that this camera has strong ability for accommodation and adapts to different eyes from-12 m-1 to +12 m-1.The field of view of this camera is 30°,the resolution at the image surface is 120 lp/mm,and the distortion value is less than 3.9%.Because of the application of aspheric elements,the structure,volume and weight of the camera are optimized,and the image quality is improved.