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Optical Engineering

Digital recording and numerical reconstruction of holograms: reduction of the spatial frequency spectrum
Author(s): Ulf Schnars; Thomas M. Kreis; Werner P. O. Jueptner
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Paper Abstract

Direct recording of Fresnel holograms on a charge-coupled device and their numerical reconstruction is possible if the maximum spatial frequency of the holographic microstructure is adapted to the spatial resolution of the detector array. The maximum spatial frequency is determined by the angle between the interfering waves. For standard CCDs with spatial resolutions of ~100 lines/mm, the angle between reference and object wave is limited to a few degrees. This limits the size of the objects to be recorded or requires a great distance between object and CCD target. A method is described in which the primary object angle is optically reduced so that objects with larger dimensions can be recorded. The principle is demonstrated for the example of deformation analysis. Two Fresnel holograms, which represent the undeformed and the deformed states of the object, are generated on a CCD target, stored electronically, and the wave fields are reconstructed numerically. The interference phase can be calculated directly from the digital holograms, without generating an interference pattern. As an application of this method, we present the transient deformation field of a plate that is loaded by an impact.

Paper Details

Date Published: 1 April 1996
PDF: 6 pages
Opt. Eng. 35(4) doi: 10.1117/1.600706
Published in: Optical Engineering Volume 35, Issue 4
Show Author Affiliations
Ulf Schnars, Bremer Institut fuer Angewandte Strahltechnik (Germany)
Thomas M. Kreis, Bremer Institut fuer Angewandte Strahltechnik (Germany)
Werner P. O. Jueptner, Bremer Institut fuer Angewandte Strahltechnik (Germany)

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