The optical manufacturing for off - axis aspheric mirrors has become increasingly challenging for two reasons . the mirrors , in addition to being larger , are more aspheric and off - axis in order to meet the requirement of next generation space camera , which is commonly configured as three - mirror - anastigmat ( tma ) to get both wide fov and high resolution , and the required accuracy is more stringent 近年来，人们提出了“离轴三反消像散” ( tma )结构来满足下一代空间相机“详查”和“宽覆盖”的技术要求，该结构中要求使用三块离轴非球面反射镜，而大口径、高精度离轴非球面反射镜的制造技术是研制tma结构空间相机的主要技术瓶颈之一。
