Single-shot two-wavelength slightly-off-axis flipping digital holography using polarization-splitting modulation

Abstract

Two-wavelength digital holography (TWDH) can extend the unambiguous range of phase measurements. However, state-of-the-art TWDH is achieved either by using the on-axis or off-axis layout to create interference or by using a Bayer mosaic-filtered color CCD camera to record the hologram. This leads to a tradeoff among the acquisition rate, detector bandwidth, and measurement depth. To solve this issue, inspired by the slightly off-axis single-wavelength digital holography, a single-shot slightly off-axis TWDH is proposed by combining flipping and polarization-splitting modulation. The interferences are yielded by flipping the relative positions of the sample and reference beams of both wavelengths. Two holograms at each wavelength can be simultaneously recorded by a monochromatic CCD camera with the help of polarization-splitting modulation. After subtraction between the two holograms, a correlative filtering division algorithm is used to perform the phase reconstruction. Experimental validation was conducted by measuring step targets and alcohol evaporation.