A method for introducing phase steps in an interferogram based on translating a ruling at the input plane of a double aperture common-path interferometer is presented. The setup is built on a 4f optical system consisting of two apertures at the input plane and a Ronchi ruling in the Fourier plane, where at each aperture a Ronchi ruling is also placed. By filtering at the Fourier plane a single diffraction order of the spectrum from the rulings in the object plane, we demonstrate that a phase step is generated when one of the rulings in the input plane is translated. The principal advantage of this proposal lies in improving the resolution in the phase step. We develop a theoretical model and show experimental results.

This paper presents a novel, simple, robust, and very stable polarimeter which is able to measure in a single-shot the state of polarization (SOP) of an optical field. In this proposal, an optical field with an unknown SOP and an optical field with a reference SOP are superposed by using a double aperture common-path interferometer (DACPI), obtaining two interferograms with adjustable carrier frequency in a single shot. Each interferogram has different visibility and phase-step where the information of the unknown SOP is contained. It is shown that under a typical Fourier analysis any SOP can be successfully measured without the necessity of knowing the carrier frequency. The present proposal is justified mathematically and probed experimentally.

This paper presents a simple and practical phase shifter able to adjust its resolution in a wide range for phase-shifting interferometry. This proposal is carried out in a double-aperture common-path interferometer, placing at the input plane an additional grating in each aperture. We demonstrate that when both gratings are rotated at the same angle, the resolution of phase-step improves considerably without the need of using a sophisticated system of high quality. This method is verified with numerical simulation and with the evaluation of several experimental interferograms.

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