摘要
In order to test mild aspheric surface directly without other null optics, the digital plane method is proposed. When departure of the tested aspheric surface is mild, a sphere mirror can be used as the reference surface. The phase distribution can be measured swiftly by the digital interferometer. The surface error can be obtained by subtracting the theory wavefront error （the value of the digital plane） from the phase data and eliminating the translation errors through least-squares fitting. The basic principle and theory of this method are analyzed and researched, and the testing model and flow chart are established. Meanwhile the experiment is carried out with a mild aspheric mirror by this method, the PV and RMS of the surface error are 0.173λ and 0.018λ （λ is 632.8 nm）, respectively. We also design and make a null corrector to the asphere for contrast, the differences in PV and RMS error between them are 0.026λ and 0.001λ, respectively.
In order to test mild aspheric surface directly without other null optics, the digital plane method is proposed. When departure of the tested aspheric surface is mild, a sphere mirror can be used as the reference surface. The phase distribution can be measured swiftly by the digital interferometer. The surface error can be obtained by subtracting the theory wavefront error （the value of the digital plane） from the phase data and eliminating the translation errors through least-squares fitting. The basic principle and theory of this method are analyzed and researched, and the testing model and flow chart are established. Meanwhile the experiment is carried out with a mild aspheric mirror by this method, the PV and RMS of the surface error are 0.173λ and 0.018λ （λ is 632.8 nm）, respectively. We also design and make a null corrector to the asphere for contrast, the differences in PV and RMS error between them are 0.026λ and 0.001λ, respectively.
基金
This work was supported by the National Natural Science Foundation of China （No. 61036015）, the National 863 Program of China （Nos. O8663NJ090, and 2011CB0132）.
