Space-time digital holography: A three-dimensional microscopic imaging scheme with an arbitrary degree of spatial coherence

An on-line, spatiotemporal, digital holographic method is described and demonstrated experimentally. Using interferometric imaging, each scatterer of a three-dimensional object is encoded as a temporally modulated Fresnel pattern, and recorded on a charge-coupled device. Temporal heterodyning of the signal from each pixel results in a single-sideband, on-line holographic record in digital form. Reconstruction of an image focused on a chosen transverse plane in the object is done by digital correlation with a reconstruction function matched to that plane. The method circumvents most of the drawbacks of both coherent and incoherent holography, and may find applications in three-dimensional imaging and microscopy. (C) 1999 American Institute of Physics. [S0003-6951(99)04640-9].