便携式免散瞳眼底相机光学系统设计

设计了一种便携式免散瞳眼底相机光学系统，达到了全视场300万像素的高清眼底成像。在考虑人眼生理特征和光学特性的基础上，引入Gullstrand-Le Grand眼模型来模拟被测屈光度正常的人眼，用Schematic眼模型来检验屈光度异常人眼对成像光路的影响。在成像系统中，首先采用接目物镜会聚从人眼视网膜反射出瞳孔的光线，然后再由成像物镜将视网膜的像成像到CCD上。在照明系统中，为避免角膜中心区域产生杂散光，采用环形光阑和共轴照明相结合的照明方式给眼底照明。仿真结果表明:该系统视场角为30，成像分辨率高于120 lp/mm，场曲值小于0.12 mm，畸变仅为-1.2%，全视场色差值均在艾里斑之内，且该光学系统具有较大的调焦能力，对-10 D~+10 D的人眼普遍适用。所用的光学元件均为普通的球面玻璃，便于加工制造且能有效降低实际的制作成本。

Optical system design of portable non-mydriatic fundus camera

An optical system of a portable non-mydriatic fundus camera was designed. This design realized the highly clear imaging with three million pixels. Based on the physiological and optical characteristics of the human eye, the Gullstrand-Le Grand eye model was introduced to simulate the human eye with normal diopter. The Schematic eye model was used to examine the influence of the ametropia eye on imaging system. In the imaging system, the eye-piece objective lens were firstly used to converge the light emitted through the pupil reflected from the retina of the human eye, then it was imaged to the CCD receiver by the imaging objective lens. In case of the stray lights caused by the cornea, the illuminating system with an annular aperture and coaxial illumination was specially designed. The result shows that the field of view of this system is 30 degrees, the resolution is more than 120 lp/mm, the field curve value is less than 0.12 mm, the distortion value is only -1.2%, the chromatic aberration of all fields of view is within the Airy disk. It comes to a conclusion that this fundus camera has strong focusing abilities for accommodation, and adapts to different eyes from -10 D to +10 D. All the optical components of the optical systems are common spherical glasses, which are easy to manufacture and can reduce the production costs effectively.