Abstract
Optical scanning holography (OSH) is a powerful and effective method for capturing the complex hologram of a three-dimensional (3-D) scene. Such captured complex hologram is called optical scanned hologram. However, reconstructing a focused image from an optical scanned hologram is a difficult issue, as OSH technique can be applied to acquire holograms of wide-view and complicated object scenes. Solutions developed to date are mostly computationally intensive, and in so far only reconstruction of simple object scenes have been demonstrated. In this paper we report a low complexity method for reconstructing a focused image from an optical scanned hologram that is representing a 3-D object scene. Briefly, a complex hologram is back-propagated onto regular spaced images along the axial direction, and from which a crude, blocky depth map of the object scene is computed according to non-overlapping block partitioned entropy minimization. Subsequently, the depth map is low-pass filtered to decrease the blocky distribution, and employed to reconstruct a single focused image of the object scene for extended depth of field. The method proposed here can be applied to any complex holograms such as those obtained from standard phase-shifting holography.
Highlights
Optical scanning holography (OSH) [1,2] is one of the most effective techniques for capturing a complex hologram of a physical scene
In this paper we present, partly based on the work in [18], a method for fast hologram reconstruction with extended depth of field (EDF)
In stage 4, an extended depth of field image of the object scene is obtained by selecting each pixel from the reconstruction image plane that corresponding to the depth of the pixel in the depth map
Summary
Optical scanning holography (OSH) [1,2] is one of the most effective techniques for capturing a complex hologram of a physical scene. It is different from existing methods such as phase shifting holography (PSH) [3], parallel phase shifting holography (PPSH) [4], geometric phase shifting digital holography (GPSDH) [5], Fresnel incoherent correlation holography (FINCH) [6,7], Fourier incoherent single channel holography (FISCH) [8], and the consumers scanner approach [9] that requires 2-D digital recording devices (e.g., digital camera) to capture the holographic signal, OSH only utilizes a single-pixel sensor. After a complex hologram is captured, it is often necessary to reconstruct a visible image from the hologram for further inspection
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