Zoom Algorithms for Digital Holography
Digital Holography is an imaging modality made up of two parts: (1) using a digital camera to record the interference pattern between a field scattered from an object and a known reference field so that the complex object wavefield can be obtained and (2) replaying or reconstructing the hologram on a computer by simulating the propagation of the object wavefield back to the object plane. Thus an image is obtained. The most commonly used algorithms for the reconstruction algorithm are the so-called direct method and the spectral method of calculating the Fresnel Transform, which describes free space propagation in the paraxial approximation. These algorithms differ in the output range that they display. For the direct method, the output image size is proportional to the distance making it more appropriate for large objects at large distances. The spectral method has an output image size equal to the size of the CCD. We show how to adapt this latter algorithm in a simple way to allow it to generate any output range and in any location making it far more versatile for zooming in on specific regions of our reconstructed image.
KeywordsFast Fourier Transform Discrete Fourier Transform Spectral Method Object Size Polarize Beam Splitter
This research is funded from the European Community’s Seventh Framework Programme FP7/2007–2013 under grant agreement 216105 “Real 3D.”
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