@ARTICLE{Maaboud_Niveen_Digital_2010, author={Maaboud, Niveen and El-Bahrawi, Mohamed and Abdel-Aziz, Fedia}, number={No 4}, journal={Metrology and Measurement Systems}, pages={583-587}, howpublished={online}, year={2010}, publisher={Polish Academy of Sciences Committee on Metrology and Scientific Instrumentation}, abstract={Digital holography (DH) which is the technology of acquiring and processing measurement data via a CCD camera is spreading to industrial applications, finds wide employment in engineering problems of testing and investigation. In this paper, a simple digital holographic system, comprising a He-Ne laser source, CCD camera and analyzing software, is used for testing surface flatness and detecting the presence of a propagating crack on the surface plane and the effect of the crack on the neighborhood. Phase variations across the surfaces planes are extracted to represent the surface deviation from a reference plane. The analysis methods differ according to the interference fringes in the recorded holograms. Both fringe tracking and Fourier transform with phase unwrapping methods are used in the interpretation of interferometric fringe patterns.}, type={Artykuły / Articles}, title={Digital Holography in Flatness and Crack Investigation}, URL={http://journals.pan.pl/Content/107076/PDF/Journal10178-VolumeXVII%20Issue4_06%20paper.pdf}, doi={10.2478/v10178-010-0047-z}, keywords={digital holography, fringe analysis, flatness testing, crack investigation}, }