Adjustable-window grating interferometer based on a Mach-Zehnder configuration for phase profile measurements of transparent samples

TLDR: In this article, a Mach-Zehnder configuration coupled to a 4-f arrangement using phase gratings placed on the Fourier plane was implemented to analyze phase objects. But the interference of the fields associated with replicated beams, centered on each diffraction order, is achieved varying the spacing of windows with respect to the grating period.

Abstract: This communication describes some details of polarization modulation that are useful in phase-shifting interferometry when applied to phase profile measurements of phase objects. Since non-destructive optical techniques allow surface measurement with high accuracy, a Mach-Zehnder configuration coupled to a 4-f arrangement using phase gratings placed on the Fourier plane was implemented to analyze phase objects. Each beam of the interferometer goes through a birefringent wave plate in order to achieve nearly circular polarization of opposite rotations, with respect to each other. The interference of the fields associated with replicated beams, centered on each diffraction order, is achieved varying the spacing of windows with respect to the grating period. Experimental results are presented for cases of four and nine simultaneously captured interferograms.