Full-field analysis of wavefront errors in point diffraction interferometer with misaligned Gaussian incidence.

The precision and accuracy of profile measurement achieved by a point diffraction interferometer (PDI) is determined by a spherical diffraction reference wavefront whose quality is mainly controlled by the pinhole's alignment. In consideration of a Gaussian beam incidence, different diffraction wavefront errors stemming from misalignment of pinhole including lateral shift, defocus, and tilt are analyzed with the help of a proposed systematic model and a new evaluation criterion established under spherical coordinates. The full-field distributions of various diffraction wavefront errors are obtained through simulation. The predicted accuracy of an actual PDI makes a good agreement with the experiment results. The achieved results will be beneficial to the accuracy evaluation of a PDI before and after its design.