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

Abstract

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.

Off-axis digital holography with multiplexed volume Bragg gratings

“…If a microscope objective is present, the angular bandwidth of the object field is limited by the numerical aperture NA of the objective : ∆θ 0 = ∆ϑ 0 = 2 arcsin(NA). A usual method to engineer a reference optical wave suitable for off-axis holographic interferometry from the object wave itself consists in reducing the spatial frequency content of the latter by low-pass filtering of the transverse projections of the transmitted angular wavenumbers (k x , k y ) with a pinhole [31,34,48,49], or by defocus by curved mirrors [50], a spatial light modulator [51], or lenses [22,52,53].…”

Pulsed digital micro-holography of femto-second order by double-wavelength recording

“…CCD has been popularly used in pulsed digital holography because of its high sensitivity and convenient interface with computers [1][2][3][4][5][6] . To record an ultra-fast event with an expose frequency higher than the frame frequency of a CCD, multiplexing technique has to be employed to record subholograms at different times on a single frame of CCD, and each sub-hologram can be reconstructed through Fourier transformation and digital filtering, as reported in the previous work focused on SADM (spatial angular division multiplexing) [7,8] and SDM (spatial division multiplexing) [9] .…”

Volume holographic spectral-spatial imaging of biological tissue

“…A variety of optical holographic methods have been considered for medical imaging applications [4][5][6] . The most recent candidates include optical scanning holography 7 , holographic optical sectioning 8 , and spectral decomposition holography 9 .…”