Spatially divided two-step phase-shifting method for computational optical scanning holography

Abstract Computational optical scanning holography (COSH) is one of the single-pixel incoherent digital holographic techniques; therefore, three-dimensional fluorescent objects can be measured as a digital hologram with a single-pixel detector. However, due to the requirement of a phase-shifting method to remove unnecessary components from holograms, the number of measurements of COSH is larger than the number of pixels. To reduce the number of measurements, the spatially divided phase-shifting method has been proposed. Similar to the parallel four-step phase-shifting digital holography, the spatially divided phase-shifting method can obtain four phase-shifted holograms simultaneously. However, the spatially divided phase-shifting method has a problem in that the spatial resolution is lower than the original COSH. In this paper, a spatially divided two-step phase-shifting method is proposed to improve spatial resolution. The numerical evaluation results indicate the feasibility of the proposed method. In addition, the proposed method is applied to microscopy for proof of principle experiment. The experimental results indicate the proposed method improves the image quality compared with the conventional spatially divided four-step phase shifting method.