为满足无遮拦三反射镜光学系统体积小、光学性能高的发展需求,提出了一种圆周式三反光学系统.以近轴矩阵法求解的共轴三反系统为初始结构,在保证各二次曲面反射镜的焦点依次衔接的条件下,将各元件适当地倾斜偏心使系统无遮拦,并使系统的光路折叠在三个反射镜所围成的区域内,减小了系统体积.使用子午面对称的Zernike多项式曲面校正系统像差,提高成像质量.设计的非致冷长波红外光学系统焦距为310 mm,F数为1.55,视场为1.774°×1.331°.各视场的调制传递函数在Nyquist频率(20 lp/mm)处均高于0.52.

In order to meet the demand that unobscured three-mirror optical systems should be small volume with excellent optical performance,a circular three-mirror optical system was proposed.A coaxial three-mirror system is calculated by the paraxial matrix as a starting point.With the condition that the focal point of each conic mirror is placed to coincide successively,elements in the system are tilted and decentered properly to make the system unobscured and to fold the optical path in the region surrounded by three mirrors to reduce the system volume.Zernike polynomial surfaces which are symmetric about tangential plane are used to correct aberrations and to improve the image quality.An uncooled long wave infrared optical system is designed at focal length 310mm,F-number 1.55 with field of view 1.774°×1.331°.The modulation transfer function of this system is above 0.52 all over the field of view at the Nyquist frequency of 20 line pairs per millimeter.