Real-time point-diffraction interferometer and its analytical formulation.

We propose a novel wavefront sensor and study its performance with an analytical formulation. The sensor has a polarizing point-diffraction beam splitter. Using transmitted and reflected beams, we can build a real-time point-diffraction interferometer with high precision and efficiency. Our analytical studies reveal that wavefront errors might be measured incorrectly and that less precise estimates of wavefronts appear as the pinhole radius R is increased. An investigation of propagating uncertainties shows that the wavefront measurement can be calibrated by estimating the pinhole effects and the polarizing properties with a precision of a few percent. Based on these studies, R should be smaller than half of the Airy disk for better performance.