Retrace error elimination for partial compensation digital Moiré phase shifting interferometry

A digital Moir phase-shifting interferometry with partial compensation lens was expounded to test the figure error of aspheric surfaces with high accuracy measurement. The real interferometer and the ideal interferometer model were established to obtain the real and ideal wavefront at the image plane of the interferometer. Then the image wavefront in the real interferometer related to the surface figure error of the aspheric surface under test was obtained by using the digital Moir phase-shifting technique. The error analysis of this measuring system was presented, and the reverse optimization procedure was applied to eliminate retrace error for the large figure error and reconstruct the test aspheric surface large figure error. Experimental results show that, compared to the profilometer, for the small figure error, the accuracy of the aspheric surface figure error measurement with the one-half method can achieve less than /20, both PV error and RMS error. For the large figure error, the reverse optimization method need to be used to obtain the accuracy of aspheric surface errors measurement of less than /5, both PV error and RMS error. Partial compensating digital Moir phase shifting interferometry for the test aspheric surface error based on reverse optimization procedure can effectively correct the retrace error, and reconstruct the large figure error of aspheric surfaces with high-accuracy.