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Fourier transform method for automatic processing of moiré deflectograms

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Quiroga Mellado, Juan Antonio and Crespo Vázquez, Daniel and Bernabeu Martínez, Eusebio (1999) Fourier transform method for automatic processing of moiré deflectograms. Optical Engineering, 38 (6). pp. 974-982. ISSN 0091-3286

Official URL: http://dx.doi.org/10.1117/1.602138




Abstract

In this work, a Fourier transform technique for automatic analysis of moire deflectograms is presented. A squared grating is used to multiplex the information of the deflection in two orthogonal directions in one image. This procedure avoids the necessity of rotating the gratings to obtain the complete deflection information. With this method only two fringe patterns. reference and distorted, are needed to determine the complete deflection information. To deal with irregularly shaped processing areas, a Gerchberg extrapolation method is used. The automatic determination of the carrier as well as the size and position of the reconstruction windows permit the complete and automatic measurement of the deflection produced by an ophthalmic lens in two orthogonal directions. Afterwards, the refractive power maps can be obtained, Experimental results obtained with a progressive addition lens are presented and comparison with measurements obtained with a commercial focimeter are shown showing a good agreement.


Item Type:Article
Additional Information:

© 1999 Society of Photo-Optical instrumentation Engineers.

Uncontrolled Keywords:Fringe-Pattern-Analysis, Deflectometry, Interferometer, Algorithm
Subjects:Sciences > Physics > Optics
ID Code:23233
Deposited On:21 Oct 2013 07:27
Last Modified:21 Oct 2013 07:27

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