可调焦胶囊内窥镜光学系统设计

Design of a Focus-tunable Capsule Endoscope System

为解决胶囊内窥镜分辨率与景深相互制约的问题，将一种单液体、电控、可变焦液体透镜应用到内窥镜光学系统中进行光学设计，在保证分辨率的同时，扩大了系统景深．采用CODEV软件进行设计，建立系统初始结构，构造液体透镜模型，基于液体透镜中液体的体积不变，曲率、孔径和厚度可变的结构约束特点，在MATLAB中计算出不同物距下透镜的曲率、孔径和厚度数据，将其导入CODEV的系统模型中，并提出了相应的优化流程．设计并优化带有液体透镜的胶囊内窥镜系统，实现了系统在3～100mm景深范围内的清晰成像，视场角大于110°，全视场范围内调制传递函数在40lp／mm频率下均大于0．3．

To solve the problem of constraint between resolution and depth of field in capsule endoscope system, a single-liquid, electron-controlled, focus-tunable len was applied into the design of capsule endoscope system. By using of liquid lens, the depth of field of system was enlarged with the required resolution. The initial system was set up by the optical design software CODE V. The liquid lens model was built according to its structure restriction. The liquid volume of the lens was constant, while the radius, the aperture and the thickness of the lens were changed during the focal length changing process. At different depth of field, the appropriate radius, aperture and thickness of the liquid lens were calculated by MATLAB, and the calculation result was imported into CODE V. The optimizing process was designed. After the optimization, in 3~100 mm depth of field, clear images can be obtained. The field of view is more than 110°, and the modulation transfer function of the system is larger than 0.3 in all field of view at 40 lp/mm.