Phase-shifting interferometry (PSI) is a well-known technique used to calculate the phase of a
resulting wavefront. This wavefront is commonly originated from the superposition of a known
reference wavefront with a distorted wavefront, resulting in an interference pattern. In order to
extract information about the resulting wavefront (which can be related to surfaces thicknesses,
surface roughness, optical power, material homogeneity, temperature, index of refraction, just to
mention a few), a set of interference patterns are generally changed in a known phase-step to form a
resoluble system of equations. In PSI the contrast, visibility and phase variations of the resulting
interference patterns are considered homogeneous and spatially constant, respectively. These
conditions are hard to obtain experimentally, even though a carefully calibrated phase shifter
and/or optical elements of high quality are used to carry out the experimental setup. In this
manuscript, we present a nove…