Design and error analysis of the CGH used for aspheric test

Design method and procedures of computer-generated hologram(CGH) used for aspheric test are introduced.Key questions about calculation of CGH phase function,selection of carrier frequency,position search of interference pattern and alignment of CGH to interferometer are discussed.Some new design notions and methods are proposed.Substrate figure error,pattern distortion,etching and duty cycle variations that influence the reconstructed wavefront are quantitatively analyzed in theory and corresponding error equations are obtained to guide the tolerance distribution during CGH fabricating.A design example is given and the uncertainty of measurement achieve.