水下大视场连续变焦光学系统设计

针对现有水下光学系统中存在的主要不足，就某大视场水下连续变焦光系统指标要求，从水下光窗选型、光窗畸变、色差等的影响入手，分析了水下平板光窗引入的相对畸变和倍率色差特性，给出了相应的应对措施。结合水下工况对包络和工作距的要求，给出了一种三组联动的变焦系统设计模型和相应调跟焦组件的设计方法；通过在PNNP型结构中引入像差稳定镜组，对动态像差做稳定和补偿，改善了光学结构的像差校正能力，同时规避了凸轮曲线断点问题；通过在物方侧镜组中设置调跟焦镜组，保证了变焦全程对近景目标的清晰成像。完成了一个4 K水下大视场连续变焦光学系统设计，该系统工作距为0.5 m~inf，设计波段为0.48~0.64 μm，采用3840×2160高灵敏CMOS面阵探测器，像元大小为2 μm，变焦全程F数最大恒定为2.8，可实现全视场5.9°~62°、10倍以上连续变焦功能，具有较短的变焦行程、平滑的变焦轨迹、优良的成像性能等优点。

Design of underwater large field of view zoom optical system

Under the requirements of an underwater large field of view zoom optical system, the selection of optical window and its influence on objective lens were discussed, by which the relative distortion and lateral color induced by the plane window were analyzed and corresponding design methods were given. Regarding the special envelope and working distance requirements of the underwater optical system, a three-part zoom system design model and the design method of the corresponding focusing components were provided by introducing aberration stabilizers in the PNNP structure, dynamic aberration correction capability of the optical structure was improved, also, the problems of the cam curve breakpoints were avoided; by setting the focus lens group in the objective parts, close-range imaging through the entire zoom range was guaranteed. A 4 K underwater large field of view zoom optical system was completed using 3840×2160 high-sensitivity CMOS detector, with 0.5 m-inf working distance, 0.48?0.64 μm work waveband, constant F number of up to 2.8 and 5.9°?62° full field of view. The image quality and tolerance characters are validated by an assembled lens and its underwater imaging experiments.