Optimized temporal excitation profiles in active thermography

Authors
Citation
U. Nezelmann, Optimized temporal excitation profiles in active thermography, ANAL SCI, 17, 2001, pp. S432-S435
Citations number
8
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
ANALYTICAL SCIENCES
ISSN journal
0910-6340 → ACNP
Volume
17
Year of publication
2001
Pages
S432 - S435
Database
ISI
SICI code
0910-6340(2001)17:<S432:OTEPIA>2.0.ZU;2-A
Abstract
The thermal response of opaque coatings after heating with pulses of finite duration is analyzed theoretically with respect to detection of small vari ations of the coating thickness. Rectangular shaped heating pulses and step pulses with exponential decay an considered. The investigation is based on existing analytical solutions for step-function heating and for delta-puls e heating. For the exponentially decaying pulse, a numerical convolution is performed. For the rectangular pulse, the best sensitivity for thickness v ariations (thickness contrast) is generally obtained 0.2 to 0.9 Fo-numbers after the end of the pulse. A good selection for the pulse length is 0.5 to 1.5 Fourier numbers of the coating. For the exponentially decaying pulse, the maximum thickness contrast is smaller than for the rectangular pulse an d easily hidden by disturbing radiation. Experimental realization of rectan gular short pulses is approximately possible by switched flash lamps.