Single-channel incoherent interferometer as a tool for recording digital holograms

Holography is an attractive imaging technique as it offers the ability to view a complete three-dimensional volume from one image. However, holography is not widely applied to the regime of white-light imaging, because white-light is incoherent and creating holograms requires a coherent interferometer system. We review our recently proposed single-channel interferometer for generating digital Fresnel holograms of 3-D real-existing objects illuminated by incoherent light. In this motionless holographic technique, light is reflected, or emitted, from a 3-D object, propagates through a diffractive optical element (DOE), and is recorded by a digital camera. The DOE is used as beam-splitter of the single-channel incoherent interferometer, such that each spherical beam originated from each object point is split into two spherical beams with two different curve radiuses. Superposition of the entire interferences between all the couples of spherical beams creates the Fresnel hologram of the observed 3-D object. Three holograms are recorded sequentially, each for a different phase factor of the DOE. The three holograms are superposed in the computer, such that the result is a complex-valued Fresnel hologram that does not contain a twin image. When this hologram is reconstructed in the computer, the 3-D properties of the object are revealed.