Harmonically-related diffraction gratings-based interferometer for quadrature phase measurements

Abstract

Abstract:We demonstrate the use of shallow diffraction gratings for quadrature phase interferometry. A single shallow diffraction grating-based Michelson interferometer yields only trivial (0 o or 180 o ) phase shift between different output ports. In comparison, a combination of two parallel shallow diffraction gratings can be useful to achieve desired phase shifts (e.g., 90 o for quadrature phase interferometry). We show that the phase at different output ports of a grating-pair based interferometer can be adjusted by shearing the two gratings with respect to each other. Two harmonicallyrelated diffraction gratings are used to demonstrate phase shift control at the output ports of a modified Michelson interferometer. Our experimental data is in good agreement with theory.

Harmonically matched grating-based full-field quantitative high-resolution phase microscope for observing dynamics of transparent biological samples

“…As is well known, a grating can confer additional phase shifts to the diffracted beams. For a shallow grating, the phase shifts can be written as [15] ] 2…”

“…Recently, our group demonstrated a full-field phase imaging technique based on the substitution of a beamsplitter with a harmonically matched diffraction grating pair (G1G2 grating) [14,15] in an interferometer -we named the technique G1G2 interferometry. With this optical element substitution, we were able to create a non-trivial phase relationship between the different output ports of the interferometer.…”

Full field phase imaging using a harmonically matched diffraction grating pair based homodyne quadrature interferometer

“…We recently demonstrated that a quadrature free-space phase interferometer, termed as the G1G2 interferometer, can be created with a pair of harmonically matched shallow diffraction gratings. 5 In this letter, we report the following: ͑1͒ the creation of the harmonically matched grating pair on a single holographic plate, ͑2͒ the use of this single optical element in place of a beam splitter in a modified Mach-Zehnder interferometer and the observation of nontrivial phase between the outputs, and ͑3͒ a demonstration of full field phase imaging, which additionally illustrates the utility of phase imaging for flow dynamics studies.A single shallow diffraction grating can be used to create a multiport ͑n ജ 3͒ interferometer. However, the outputs of such an interferometer are trivially related in phase.…”

Observing dynamics of transparent samples by harmonically matched grating-based full-field quadrature phase interferometer

“…Previously, we have developed a full-field phase imaging technique based on a harmonically matched diffraction grating pair (G1G2 grating) 15,16 . The grating is used as a beam splitter in a Mach-Zehnder interferometer to confer nontrivial phase shift between the two output ports of the interferometer.…”