A parallel common path phase-shifting interferometer is presented using a digital reflective grating realized by a digital micromirror device (DMD). The interferometer based on a modified Michelson architecture is constructed by a beamsplitter, a pinhole mirror, a digital reflective Ronchi grating and two lenses with same focal length to build a 4f optical system. In the interferometer, the pinhole mirror is used to low-filter the input-beam to act as reference beam, and the grating is used to introduce phase shift among +1, 0, and −1 diffraction orders of the input-beam to act as object beam. Then the specimen phase can be reconstructed from the three phase-shifted interferograms recorded in one shot using a normalize algorithm. The theoretical analysis and experiments are carried out to demonstrate the feasibility and accuracy of the proposed method.
A reflective off-axis point-diffraction interferometer based on Michelson architecture is built to measure static and dynamic quantitative phase in a single shot. The interferometer is constructed by a beam-splitter, a pinhole mirror, a reflective mirror and two lenses to build a 4f optical system. The pinhole mirror is used as a low-pass spatial filter to generate reference wave. By tilting the reflective mirror, a small angle is created between the object beam and the reference beam to enable an off-axis interferogram. To reconstruct an interferogram with a few fringes, Kreis Fourier method is used to recovery the specimen phase. Using a plano-convex cylinder lens and an evaporative alcohol drop as the specimens, experiments are run to verify the effectiveness and robustness with this interferometer. Experimental results show that this interferometer has not only simple setup and good anti-interference performance, but also good real-time ability, which makes it suitable for dynamic phase measurement.