Fresnel incoherent correlation holography (FINCH): a review of research

Abstract

In this review, we describe our method for creating holograms of incoherent objects, dubbed Fresnel incoherent correlation holography (FINCH). FINCH creates holograms by a single-channel on-axis incoherent interferometer process. Like any Fresnel hologram, the object is correlated with quadratic phase functions, but the correlation is carried out without any movement. Generally, in the FINCH system, light is refl ected, or emitted, from a three-dimensional (3D) object, propagates through a spatial light modulator (SLM), and is recorded by a digital camera. The SLM is used as a beam-splitter of the singlechannel incoherent interferometer, such that each spherical beam originated from each object point is split into two spherical beams with two different curve radiuses. Incoherent summing of the entire interferences between all the couples of the spherical beams creates the Fresnel hologram of the observed 3D object. When this hologram is reconstructed in the computer, the 3D properties of the object are revealed. In this review, we describe various aspects of FINCH which have been described recently, including FINCH of refl ected white light, FINCH of fl uorescence objects, a FINCH-based holographic fl uorescence microscope, a FINCH confi guration which capitalizes on the polarization sensitivity of the SLM and fi nally FINCH is analyzed in view of linear system theory.

Fresnel incoherent correlation holography with single camera shot

“…2), while the information from all the other planes namely -N/2 to n-1 and n+1 to N/2 appear blurred with lesser intensity. Farther a plane from the plane n, higher the blur is and lower the intensity and vice versa 19 .…”

Single-shot and lensless complex-amplitude imaging with incoherent light based on machine learning

“…An established approach for complex-amplitude imaging, in which the transmittance/reflectance and phase delay of an object are observed, is digital holography (DH) [2][3][4][5]. DH basically assumes coherent illumination, such as a laser, but several incoherent DH methods have been proposed [6][7][8][9][10].…”

Enhanced resolution in Fourier incoherent single channel holography (FISCH) with reduced optical path difference

“…Fourier incoherent single channel holography (FISCH) is a recently developed method for recording digital Fourier holograms of spatially incoherent scenes [1]. Its development followed the successful realizations of the Fresnel incoherent correlation holography (FINCH) system [2][3][4][5], and was inspired by the many advantageous properties of FINCH, which are also inherent in FISCH.…”

“…In the hologram reconstruction process, overlapping and inseparable light (i.e., information) that is emitted from the two images, and from the 0th order term, renders the resulting reconstruction unusable, as it appears blurry and noisy. Consequentially, one must find a way to eliminate the twin image and the unwanted 0th order term, usually by applying a phase-shifting procedure [2][3][4][5][6][7] that requires at least three exposures. This procedure is necessary in FINCH, so even if a SLM is not used in any FINCH dual-path configuration, alternative phase-shifting devices (e.g., phase retarders, piezo mounted mirrors) are still needed.…”

“…Equation 7contains three terms that represent the 0th order, the point source image, and its twin. Assuming a proper separation of these three terms (with large enough s r ), or the elimination of the unwanted terms, using a phase-shifting procedure [5], the point source image can be shown to be proportional to [11]: is the transverse magnification of the point source, in its reconstruction plane. In view of a recent publication [12], showing that FINCH violates the Lagrange invariant [13], it is interesting to check how FISCH stands in relation to this general law of imaging systems.…”