Common-path interferometer with a tri-window

Abstract

A common-path interferometer is proposed with a tri-window. It is built using a 4f optical system with Ronchi ruling as a spatial filter. The input rectangular aperture is formed by three windows; the central window supports a phase object, and the other two are used for reference beams. Using an appropriate grating period relative to input aperture size, an interferogram containing three patterns can be obtained in the output plane. The object phase can then be reconstructed from the three patterns using just one interferogram. The experiments are carried out to demonstrate the feasibility and reliability of the proposed scheme.

Common path interferometer based on the modified Michelson configuration using a reflective grating

“…To achieve the interferograms with comparable intensities, as many others did [16,21,22], only orders 0 and 71 of the object beams can be considered during the process of interference. The intensity distributions of the three phase-shifted interferograms formed by the reference and object beams of orders 0 and 7 1 in the output plane, respectively, can, then, be expressed as…”

“…To solve the amplitude interferogram modulation caused by the grating [11,21,22], the normalized algorithm [16] is utilized to retrieve the phase distribution of the measured specimen as follows:…”

“…Traditional interferometers [5][6][7][8], such as the Mach-Zehnder or Michelson interferometers, are subject to error because of environmental effects such as vibrations, air turbulence, and temperature on the wide separated paths of the object and reference beam. Thus, common-path interferometers [9][10][11][12][13][14][15][16][17] are of growing interests due to the inherent robustness in the setup, where the object and reference beam travel almost in the same path. For example, Shaked [13] proposed an off-axis common-path interferometer using a modified Michelson architecture.…”

“…However, this method has high complexity and difficulty in system mounting and adjusting, and requires measurement of the reference field in advance. To offer simplicity in terms of procedure and setup, our group proposed a tri-window common-path interferometer [16,17] using the parallel phase-shifting characteristic of transmission grating. It includes three windows in the input plane and a transmission grating in the Fourier plane of a 4f system to achieve three phaseshifted interferograms in a single camera shot.…”

“…In this paper, we present a common-path interferometer using a modified Michelson architecture with a reflective grating inspired by a previous work [13][14][15][16][17][18][19]. This method offers simplicity in terms of procedure and setup without loss in the utilization of the input plane field of view.…”