Subsurface flaw detection in metals by photoacoustic microscopya

Autor:	R. L. Thomas, P. K. Kuo, Allan Rosencwaig, J. J. Pouch, L. D. Favro, Y. H. Wong
Rok vydání:	1980
Předmět:	Materials science Microscope business.industry Resolution (electron density) General Physics and Astronomy Thermal diffusivity Signal Crystallographic defect law.invention Optics law Microscopy Boundary value problem Diffusion (business) business
Zdroj:	Journal of Applied Physics. 51:1152-1156
ISSN:	1089-7550 0021-8979
DOI:	10.1063/1.327726
Popis:	The scanning photoacoustic microscope (SPAM) is used in both the conventional and phase‐contrast modes to detect a well‐characterized subsurface flaw in Al. The physical mechanism is that of thermal diffusion, with a subsurface probe depth and flaw resolution length of approximately one thermal‐diffusion length. Comparison of the dependences of the photoacoustic signal upon chopping frequency from the different regions of the sample confirm that the differential signal from the flaw corresponds to a transition from thermally thick to thermally thin boundary conditions. Experimental results are in good agreement with calculations based upon a three‐dimensional thermal‐diffusion model.
Databáze:	OpenAIRE
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