Improvement of the signal-to-noise ratio in interferometry using multi-frame high-dynamic-range and normalization algorithms

Using both high dynamic range (HDR) and normalization methodologies, we show a method to improve the fringe pattern contrast in interferometric measurements normally used for phase recovering. In a simulated interferogram that mimics the main effects that can be found in an interferometric process (stray-light, photon noise, electronic noise, scattering phenomena, etc.) it was possible to improve the contrast of the fringes and to decrease the root mean square error by more than 35%. The method proposed is applied to experimental interferograms to measure wavefront error and retardance changes on liquid crystal (LC) devices. It is done by using a Mach-Zehnder set-up in which we used different polarization areas. The proposed method increases the quality of the phase recovered and decreases the root mean square error by 50%. (C) 2011 Elsevier B.V. All rights reserved.