NDE2015, Hyderabad November 26-28,2015 Application of digital holography for NDE of metallic tubes using thermal loading Retheesh R 1 , Boni Samuel 1 , P. Radhakrishnan 1 , V. P. N. Nampoori 1 and A. Mujeeb 1, 2 1 International School of Photonics, Cochin University of Science and Technology(CUSAT), Kochi 682022, India 2 LBS Centre for Science and Technology, Thiruvananthapuram 695033, India Presenting author Email: mailtoretheesh@gmail.com,mob:9496129087 Abstract Optical Non-Destructive Evaluation (NDE) techniques are attractive because of its diverse application and non-hazardous nature. These techniques are widely used for measuring surface deformations of objects with and without load applied to the specimen. With the advancement of laser technology, Optical Holography and Speckle techniques are used as powerful inspection tools for NDE of specimens both in laboratory and industrial environments. Digital holography is a feasible optical tool to measure thermally induced deformation fields. This paper demonstrates the application of wave front splitting holographic set up for evaluating thermally loaded metallic tube having holes drilled in it. Holographic interferograms are recorded at different stages of thermal loading using a CMOS camera with a pixel size of 220µm.The present study employs H-Digital Holographic Software which supports Fresnel approximation technique for numerical reconstruction and processing of these digitally sampled holograms. Intensity and corresponding interference phase of the double exposure fringe patterns are acquired through subtraction of the reconstructed intensity and phases respectively of the unloaded and the loaded holographically recorded object wavefronts. Keywords: digital holography, thermal loading, Fresnel approximation, numerical reconstruction --------------- 1. Introduction Digital holography has turned out to be a powerful online inspection tool for non-destructive testing and has been broadly applied in both Science and Engineering such as fluid mechanics, microscopy, profile measurement, 3D object recognition, deformation measurement, vibration analysis and so on. This category of holography usually incorporates recording an optical field emanating from an illuminated specimen in a diffraction plane and numerically estimating the optical wave field dispersion in the reconstruction plane [1]. During the numerical reconstruction process, not only the intensity, but also the phase information of the recorded wavefield can be calculated from the digitally sampled hologram [2]. One of the most significant contributions of digital holography from a practical viewpoint is holographic interferometry, to which the broad More info about this article: http://www.ndt.net/?id=21089