基于Zemax的大视场水下成像光学系统设计

Design of underwater imaging optical system with large field-of-view based on Zemax

水下成像是海洋探测的重要手段,为满足海底微光以及大视场成像需求,利用光学设计软件Zemax设计了一款总长70mm,相对孔径为1/1.5,视场角为90°的水下成像光学系统。系统采用反远距结构,优化后仅由7片球面透镜和1片平板水密窗口组成,系统具有结构简单紧凑、大视场和大相对孔径等优点。设计结果表明,在各视场内,弥散斑的均方根半径均被控制在7μm范围内,且调制传递函数曲线在奈奎斯特频率为56lp/mm处的值均高于0.45,系统具有优异的成像质量。在单个探测像元内,系统的衍射能量大于90%,能量集中度高。此外,公差分析结果显示,系统具有较好的稳健性,且加工工艺易于实现。设计满足水下成像系统对大孔径和大视场的需求,具有重要的应用价值。

Underwater imaging is an important means in ocean exploration. An underwater imaging optical system with a total length of 70mm, relative aperture of 1/1.5, and field-of-view(FOV) angle of 90° was designed with Zemax for low light level and large FOV imaging in the ocean. Based on inverse tele-structure, the system, which was consisted of seven pieces of spherical lens and one piece of flat watertight window, has the advantages of simple and compact structure, large FOV and large relative aperture. The Root Mean Square(RMS) radius of the diffused spot in each field of view was controlled within 7μm, and the Modulation Transfer Function(MTF) values at the Nyquist frequency of 56lp/mm were all better than 0.45, which indicated that the system has good imaging quality. The diffraction energy of system was greater than 90% in a single detection pixel, indicating that energy concentration was higher. In addition, tolerance analysis results showed that the system has good robustness and easy processing technology. In conclusion, this design can meet the requirements of large FOV and large relative aperture for underwater imaging system, and has great application values.