提出了一种采用液体透镜(LTL)补偿人眼屈光度变化的新型眼底相机光学系统，应用高斯括号法推导了液体透镜光焦度与人眼屈光度的函数关系式，计算并搭建了包含人眼模型的眼底相机近轴光学系统。在优化过程中控制人眼瞳孔位置与液体透镜共轭并保证位于它们之间的光学系统放大率接近1，使成像光束能够通过液体透镜；光源与角膜共轭，采用环形光源结合偏振光照明，并在探测器前加入检偏器降低系统杂光。设计并研制了视场角为50°、物方工作距为40 mm、总长小于220 mm的便携式眼底相机光学系统，拍摄了不同屈光度状态下的模型眼在采用液体透镜和不采用液体透镜补偿的眼底图片，结果表明：通过液体透镜的电控变焦能对-10 D～+10 D(1 D=1 m-1)的人眼清晰成像。该系统结构紧凑、无机械运动部件，大幅降低了光机系统的复杂程度。

A novel fundus camera with liquid tunable lens (LTL) to compensate the ametropia of human eye is designed and developed. The formula for the power of the LTL related to the diopter of eyes is deduced by Gaussian brackets method. The paraxial optical system of the fundus camera with ophthalmophantom is calculated and modeled. To enable the imaging beam to pass through the LTL without obscuration, the eye pupil and the LTL are conjugate with each other with respect to the lens system between them, and the lens system should have a magnification approximately to 1. To eliminate the stray light, the light source and the cornea are conjugate with each other in the illumination system, ring-shaped light source combined with polarized light is used. Besides, an analyzer plate is placed after the beam splitter to block the light reflected from the lenses and cornea. The fundus camera has a field of view of 50°, working distance of 40 mm, and overall length of 220 mm. Experiment is carried out to demonstrate the diopter compensation capability of the system, in which fundus images of ophthalmophantom at different diopters are captured, and these images are compared with those of the system where no LTL is adopted. The results show that by means of using LTL, the camera can adapt to eyes with diopter range from -10 D to +10 D (1 D=1 m-1). This compact system with LTL can remarkably simplify the optomechanical structure while maintaining a good diopter-adjusting performance.