自由曲面变焦的内调焦式光学系统设计

Design on internal focusing optical system with zoom lens of freeform

  • 摘要: 具有调焦功能的光学系统在空间探测领域中有着重要的应用需求。设计了一种基于自由曲面垂轴偏移的内调焦光学系统,该系统中采用特殊自由曲面面型结构,构建自由曲面透镜组,利用垂轴偏移的变焦特性,改善光学系统的成像位置,提升在空间环境多样性和宽物距成像的适应性能力。具体分析了自由曲面透镜组的调焦原理,并成功将自由曲面透镜组应用到焦距为100 mm的光学系统中,分析像距扰动和物距变化两种情况下的成像质量和偏移量。结果表明,光学系统的调制传递函数在奈奎斯特频率处大于0.3,满足成像要求,该系统具有成像性能稳定和微米量级补偿量等特点。

     

    Abstract: Optical systems equipped with focusing ability are crucial for space exploration. The internal focusing optical system was designed which was based on the vertical deflection of the freeform surface. Specifically, the system used a special structure of the freeform surface to establish a lens group. It used the zoom ability of the vertical deflection to improve the imaging location thus adapting to different conditions such as wide range imaging or diverse space environments. The zoom theory of the freeform lens group was analyzed, and zoom lens of freeform was successfully applied to the optical system whose focal length was 100 mm. Then the imaging quality and displacements were analyzed when the object and image distance were changed accordingly. The results show that the Modulation Transfer Function (MTF) of the optical system is better than 0.3 at the Nyquist frequency which means satisfying quality of image. The system is stable in imaging and can provide compensation on the micron scale.

     

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