HAL Id: jpa-00227020
https://hal.archives-ouvertes.fr/jpa-00227020
Submitted on 1 Jan 1987
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NON DESTRUCTIVE EVALUATION AND THERMAL CHARACTERIZATION BY THE
PHOTOTHERMAL BEAM DEFLECTION
F. Lepoutre, J. Roger, E. Legal Lasalle
To cite this version:
F. Lepoutre, J. Roger, E. Legal Lasalle. NON DESTRUCTIVE EVALUATION AND THERMAL
CHARACTERIZATION BY THE PHOTOTHERMAL BEAM DEFLECTION. Journal de Physique
Colloques, 1987, 48 (C7), pp.C7-771-C7-771. �10.1051/jphyscol:19877194�. �jpa-00227020�
JOURNAL DE PHYSIQUE
Colloque C7, suppl6ment au n 0 1 2 , Tome 48, dkcembre 1987
NON DESTRUCTIVE EVALUATION AND THERMAL CHARACTERIZATION BY THE PHOTOTHERMAL BEAM DEFLECTION
F. LEPOUTRE, J.R. ROGER and E. LEGAL LASALLE
Laboratoire dlOptique Physique, CNRS ER-5, E c o ~ ~ Superieure de Physique et Chimie, 10, Rue Vauquelin, F-75231 Paris Cedex 05, France
The photothermal methods are known to be a useful tool for thermal characterization of materials. Among all these methods only those for which accurate theoretical models are available allow quantitative measurements. In addition it is often necessary to test locally large samples without any contact. All these conditions are fulfilled by the photothermal beam dkflection (mirage effect). Let us recall that this optical method uses a first modulated light beam (pump beam) to heat the sampletand a second beam (generally from a small He-Ne laser) which is deflected by the thermal gradient in the vicinity of the sample surface (probe beam).
We present in this paper new developments of the theory of the mirage effect which are of importance for usual experiments with this technique :
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Effects related to the detection along a line crossing the thermal distribution.-
Convolution effects due to the finite size of the probe beam.-
Lost of contrast in the observation of the subsurface defects due to the finite size of the pump beam.The theoretical model is physically explained and the experi- mental consequences of these effects are developed :
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Thermal measurements in poor heat conductors,-
Experimental arrangements to prevent the convolution effects,-
Examples of non destructive evaluation with conventional and laser pump beams.Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19877194
