Automatic processing in Moiré deflectometry by local fringe direction calculation



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Quiroga Mellado, Juan Antonio and Canabal Boutureira, Héctor and Bernabeu Martínez, Eusebio (1998) Automatic processing in Moiré deflectometry by local fringe direction calculation. Applied Optics, 37 (25). pp. 5894-5901. ISSN 0003-6935

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An algorithm for accurately extracting the local fringe direction is presented. The algorithm estimates, in the neighborhood of n × n points, the direction of the gradient that points normal to the local fringe direction. The performance of four different derivative kernels is also compared. Since this method is sensitive to noise and variations in background and amplitude, a preprocessing step is used to limit these error sources. The method has been applied to the moiré deflectogram of a spherical and a progressive addition ophthalmic lens, resulting in a map of the refractive power of these lenses. The results are compared with the data obtained with a commercial focimeter. This technique is useful for analyzing the fringe patterns where the fringe direction is variable and must be obtained locally.

Item Type:Article
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© 1998 Optical Society of America.

Uncontrolled Keywords:Patterns, Maps
Subjects:Sciences > Physics > Optics
ID Code:23243
Deposited On:21 Oct 2013 07:39
Last Modified:07 Feb 2014 10:59

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