Author/Editor		Goetz, Catherine; Batsale, Jean-Christophe; Mourand, David
Title		Fast processing methods for thermal non-destructive evaluation of thin plates with low cost infrared cameras
Type		članek
Source		Image Anal Stereol
Vol. and No.		Letnik 20, št. Suppl 1
Publication year		2001
Volume		str. 227-32
Language		eng
Abstract		Non destructive evaluation of a thin solid plate with flash method consists in exciting the sample by a heat pulse on the front face of the plate and recording the images of temperature responses on the front or rear face by infrared thermography. The adapted processing of the successive images allows to estimate a cartography of thermophysical properties (diffusivity, thermal conductivity, volumic heat, thickness...) related to the heterogeneities of the tested sample. n such a case, the heat transfer can be considered as 1D following the thickness of the sample. Then, the transient behavior of each pixel is assumed to be non correlated with the neighbors. Nevertheless, the behavior of the average of the image can be used as a reference signal in order to implement fast processing. We present, in this framework, two identification methods which can be implemented in real time in order to develop cheap control or discrimination devices, even if the signal is noisy (with low cost infrared devices): -a method based on the estimation of thermophysical parameter variations around a nominal value by an asymptotic gradient development. -a variant of the previous method based on a weighted sum of images in order to estimate the relative variations of thermophysical properties. Some experimental results and technical characteristics will be presented.
Descriptors		THERMOGRAPHY INFRARED RAYS MATERIALS TESTING IMAGE PROCESSING, COMPUTER-ASSISTED