Null corrector forΦ1200 F/1.5 paraboloidal mirror must compensate 0.087mm surface departure from the best fitting sphere

and realize the surface error less than 0.033λ（RMS）. The design

error analysis

manufacturing

certification and final application of the corrector are introduced in detail. The certification by computer-generated hologram (CGH) in advance shows that the shape and conic errors produced by corrector are 0.012λ（RMS）and 0.0064%

and the final null testing results

surface and conic error

of primary mirror are 0.027λ（RMS）and 0.0306%

all these are consistent with the tolerance analysis. The results indicate the design ，tolerance analysis and quality of corrector are rational and reliable

and this has laid solid foundation for the null test of larger fast primary mirror.