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

Abstract

Our group has reported the use of harmonically matched diffraction grating for full-field quantitative phase imaging. In this paper, we show the improvement of this technique and the application in observing dynamics of transparent samples. By using the grating as a beam splitter/combiner in an interferometer, we are able to obtain non-trivial phase difference between the output ports of the grating. We have built a Mach-Zehnder interferometer using the holographic grating with 600 and 1200 lines/mm spacing. Two CCD cameras at the output ports of the grating-based Mach-Zehnder interferometer are used to record the full-field quadrature interferograms, which are subsequently processed to reconstruct the phase image. Since the two quadrature interferograms are acquired at the same time, the imaging speed of the system is limited only by the frame rate of the CCD cameras. We have demonstrated the capability of our system by observing dynamics of transparent samples.

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