Review of Fresnel incoherent correlation holography with linear and non-linear correlations [Invited]

Abstract

Fresnel incoherent correlation holography (FINCH) is a well-established incoherent imaging technique. In FINCH, three selfinterference holograms are recorded with calculated phase differences between the two interfering, differently modulated object waves and projected into a complex hologram. The object is reconstructed without the twin image and bias terms by a numerical Fresnel back propagation of the complex hologram. A modified approach to implement FINCH by a single camera shot by pre-calibrating the system involving recording of the point spread function library and reconstruction by a nonlinear cross correlation has been introduced recently. The expression of the imaging characteristics from the modulation functions in original FINCH and the modified approach by pre-calibration in spatial and polarization multiplexing schemes are reviewed. The study reveals that a reconstructing function completely independent of the function of the phase mask is required for the faithful expression of the characteristics of the modulating function in image reconstruction. In the polarization multiplexing method by non-linear cross correlation, a partial expression was observed, while in the spatial multiplexing method by non-linear cross correlation, the imaging characteristics converged towards a uniform behavior.

Enhanced Reconstruction of Spatially Incoherent Digital Holograms Using Synthetic Point Spread Holograms

“…The FINCH experiment was carried out using randomly multiplexed diffractive lenses mounted between the object and the image sensor [9,10]. Two FINCH holograms were recorded: PSF and object hologram as shown in Figure 2a,b, respectively.…”

“…The resulting hologram, when propagated to one of the image planes, yields an edge-enhanced image of the object. A similar approach was attempted in FINCH with the reconstruction method of CAI in a simulative study, and no edge enhancement was noticed [9,10]. In FINCH, the original reconstruction mechanism is independent of the modulating function, and whether the phase mask is quadratic or quadratic with a vortex filter, the hologram is numerically propagated to one of the image planes.…”

Roadmap of incoherent digital holography

“…However, there are still certain areas of study and applications where COACH is still relevant. For instance, incoherent holographic systems in which the two-beam interference is essential for the required application [76,77,90]. Another application that emphasizes the superiority of COACH over I-COACH, and other techniques, is the recently proposed system termed one-channel-at-a-time incoherent synthetic aperture imager (OCTISAI) [91].…”

“…Another aspect investigated deeply lately is the FINCH that can record color digital holograms [75]. Recently, the traditional Fresnel backpropagation has been replaced by a nonlinear reconstruction algorithm to improve the signal-to-noise ratio of reconstructed images [76].…”

3D Incoherent Imaging Using an Ensemble of Sparse Self-Rotating Beams

“…FINCH does have weaknesseslower axial and temporal resolutions than direct incoherent digital imagingand research has been focused on improving those limitations [11][12][13][14]. In addition, FINCH requires two-wave interference, leading to a complicated setup with several optical components, such as lenses, polarizers, and active devices, to create phase-shifted holograms.…”