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 (3D) 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, spatially divided two-step phase-shifting method is proposed to improve spatial resolution.
The numerical evaluation results indicate the feasibility of the proposed method.

Computational Optical Scanning Holography

“…One problem with SDPS is its lower spatial resolution compared with conventional COSH. To address this issue, the two-step phase-shifting method [63] was introduced to SDPS [64]. The conceptual diagram of this method is shown in Figure 10.…”

“…Typically, to acquire the complex amplitude distribution from two holograms, some algorithm is required to remove the bias component present in the hologram [65][66][67]. The two-step phase shift-based SDPS in COSH addresses this problem by utilizing information from the object's intensity sum to obtain the bias component in the hologram [64]. Therefore, the number of measurements in this method is N + 1, where N is the number of pixels, with the additional measurement aimed at acquiring the intensity sum from the object.…”