In order to find an optimal supporting scheme for the reference mirror in a 300 mm interferometer

horizontal supports were modeled and analyzed in adhered spot edge support and band-back support using finite element method. For the sake of simplicity and economy

the ringy-band support with 10 mm wrap bandwidth was accepted to optimize the design

the ideal surface deformation of the reference mirror due to self-weight was obtained in the optimal support scheme. According to this result

a certain allowance was given for deformation when the mirror blanks were polishing. Then the surface of this mirror under practical condition was measured through building absolute liquid reference. By comparison

the differences of PV magnitudes and RMS values are only 0.008 λ and 0.005 λ

respectively. It is clear that the structural design of the interferometer reference mirror meets technical requirements very well. At last

several suggestions were given to eliminate the effects of thermal turbulence.