主要研究了平面系统成像引入像差的问题。由于平面系统的工作面为平面, 平行光束入射、出射光也是平行光束, 不会引起像差。一般认为, 对于平面系统成像不引入像差, 对于平面反射镜, 同心光束经平面反射镜后仍然是同心光束, 不存在像差, 但对于棱镜系统和平行平板, 只有在近轴条件下才能理想成像, 在离轴角较大时, 会引起像差, 即同心光束经棱镜系统和平行平板后不再是同心光束。

The problem whether plane system imaging induces astigmation is researched. For the operation surface in plane system is flat, incidence beam is parallel, outgoing beam is parallel, so the astigmation can not be induced. In general, astigmation is not induced during plane system imaging process. According to research, for plane reflecting mirror, homocentric beam reflected by plane mirror is still homocentric and astigmation is not in. duced. But for prism system and parallel plate, ideal imaging can be performed only at the paraxial condition. When off-axis angle is larger, astigmation will be induced and homocentric beam passing prism system and par. allel plate is not homocentric any more.