The resolution of the reconstructed wave by a phase-retrieval method using a volume-speckle field depends on the aperture defined by the size of the CCD array. The use of a larger aperture is introduced by measuring the speckle field at two different positions in the transverse plane and stitching the measurements together. Improvements in the quality of reconstructions are demonstrated experimentally and by computer simulations. Undesirable effects of camera tilt on the quality of reconstructions from synthetic aperture intensity measurements are experimentally observed and corrected.
"Instead of the regular diffraction patterns used in , speckle intensity measurements were input into the iterative phase retrieval algorithm . Sub-pixel scanning  to enhance the speckle measurements and aperture synthesis  to increase the effective numerical aperture, were also demonstrated. The multiple intensity approach   has also been adapted to reconstruct smooth or low-curvature wavefronts. "
[Show abstract][Hide abstract] ABSTRACT: An innovative setup for the speckle-based phase retrieval method is proposed. In the conventional setup, a plane wave illuminates the test object and the transmitted wavefront is incident on a diffuser aperture generating a speckle field. The sampled speckle intensities at axially displaced planes are input into a phase retrieval algorithm based on a wave propagation equation. In the new setup, the arrangement of the diffuser and the object is reversed. A plane wave incident on the diffuser generates a speckle field which, in turn, is used to illuminate the object. The transmitted wavefront is then directed to the camera sensor. The advantage of the proposed setup is the increased resolution since the limiting aperture is the full area of the sensor.
Journal of the European Optical Society Rapid Publications 01/2009; 4. DOI:10.2971/jeos.2009.09002 · 1.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Here we highlight special techniques of DH that combine the numerical processing capabilities with variations on the hardware
configurations. In this and the following chapters, we survey some of the large number of novel techniques and capabilities
that are made possible by digital processing of holograms. We will also see that many of these techniques finally provide
highly effective solutions to problems that have been known in conventional holography.
Springer Series in Optical Sciences 01/2011; 162. DOI:10.1007/978-1-4419-7793-9_10
[Show abstract][Hide abstract] ABSTRACT: Resolution in digital holography microscopy can be improved by enlarging the hologram aperture. We review different techniques for resolution enhancement in digital holography, and present a system for reconstructing single-exposure online (SEOL) digital holograms with improved resolution using a synthetic aperture. In our method, several recordings are made in order to compose a synthetic aperture, shifting the camera within the hologram plane. After processing the synthetic hologram, an inverse Fresnel transformation provides an enhanced resolution reconstruction. The method employs a simple set-up, including no microscope objective. Experimental results with a test target are presented.
Proceedings of SPIE - The International Society for Optical Engineering 01/2007; DOI:10.1117/12.758266 · 0.20 Impact Factor
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