立体成像眼底相机光学系统设计

为了实现从不同角度同时拍摄同一眼底视网膜区域的图像,使采用双目立体视觉法进行眼底三维重建成为可能,设计了一种免散瞳立体成像眼底相机光学系统。该光学系统由成像系统和照明系统两部分组成,在成像系统中,使用Gullstrand-Le Grand眼模型来模拟正常人眼,运用体视显微镜成像原理进行分光设计;在照明系统中,通过设置黑点板的方式消除网膜物镜产生的杂散光,并加入环形光阑以避免角膜反射光的产生。设计结果表明,本立体成像眼底相机光学系统截止频率在95lp/mm处各视场的MTF值均大于0.2,成像系统畸变小于-3%,场曲值小于0.1mm,色差矫正良好,并且具有较强的调焦能力,能对-10~+5m~(-1)的人眼清晰成像。

Design of optical system for stereo imaging fundus camera

A nonmydriatic optical system for stereo imaging fundus camera was designed in this work. It could simultaneously capture two images of the same fundus retinal region from different angles, and could enable three-dimensional reconstruction of the fundus. It comprised an imaging system and a lighting system. In the imaging system, the Gullstrand-Le Grand eye model was used to simulate the normal human eye, and the principle of stereomicroscope was employed to design the splitting optical system. In the lighting system, the stray light produced by the retinal objective lens was eliminated using a black dot board, and an annular diaphragm was used to prevent corneal light reflection. Simulation results reveal that the modulation transfer function of each visual field at the cut-off frequency of 95 lp/mm is greater than 0.2, the distortion of the imaging system is less than -3%, and the field curvature is less than 0.1 mm. The stereo imaging system is highly efficient in chromatic aberration correction and focusing, and can provide clear images for the human fundus with the diopters ranging from -10 m^-1 to +5 m^-1.