A new wavefront reconstruction method for shearing interferograms with central obscurations

In the measurement of the wavefront aberration of on-axis reflective optical systems using shearing interference technology, there will be obscurations in the interferogram. However, the present wavefront reconstruction methods in shearing interference are mainly appropriate for circular or rectangular region. A wavefront reconstruction method is proposed which can apply to shearing interfergroams with central obscurations. The proposed method is a modal method based on Zernike annular polynomials. Effects of different shear ratio, different aberration and different noise on reconstruction accuracy are evaluated. The results show that this method has higher accuracy, the relative reconstruction error is below 10% with the shear ratio less than 6%, the reconstruction accuracy of astigmatism is higher than that of spherical aberration and coma, and has good noise immunity. This method is already used in the interferogram processing of cross grating lateral shearing interferomer developed in the laboratory.