讨论了双贴合无光焦度校正板放在次镜后的双反射球面系统．根据像差理论分析了消像差的条件，研究了主镜的相对孔径变化、校正板在次镜后的位置变化以及无光焦度校正板的正负透镜的不同组合形式对系统高级残余像差的影响．结果表明：当主镜的相对孔径增加或校正板靠近次镜时，系统的残余像差增加；无论校正板的第一个透镜是正透镜还是负透镜，系统在某一光焦度处残余像差最小，并且靠近次镜的透镜最好采用负透镜．

A two-sphere system with a two-lens zero-power corrector placed behind the secondary mirror was discussed. According to third-order aberration theory,the conditions of the absence of aberrations were analyzed,and the influences to the remaining high order aberrations of the system caused by the change of the relative aperture of the primary mirror,the position of the corrector and the different combination of the positive and negative lens in the corrector were investigated. The results show that the remaining aberrations will increase if the relative aperture of the primary increase or if the corrector approaches the secondary mirror. No matter the first lens of the corrector is positive or negative,there would be a particular optical power which causes smallest remaining aberrations,and it's better to use a negative lens near the secondary mirror.