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Optical method for determining the mechanical properties of a material

United States Patent

December 1, 1998
View the Complete Patent at the US Patent & Trademark Office
Disclosed is a method for characterizing a sample, comprising the steps of: (a) acquiring data from the sample using at least one probe beam wavelength to measure, for times less than a few nanoseconds, a change in the reflectivity of the sample induced by a pump beam; (b) analyzing the data to determine at least one material property by comparing a background signal component of the data with data obtained for a similar delay time range from one or more samples prepared under conditions known to give rise to certain physical and chemical material properties; and (c) analyzing a component of the measured time dependent reflectivity caused by ultrasonic waves generated by the pump beam using the at least one determined material property. The first step of analyzing may include a step of interpolating between reference samples to obtain an intermediate set of material properties. The material properties may include sound velocity, density, and optical constants. In one embodiment, only a correlation is made with the background signal, and at least one of the structural phase, grain orientation, and stoichiometry is determined.
Maris; Humphrey J. (Barrington, RI), Stoner; Robert J. (Duxbury, MA)
Brown University Research Foundation (Providence, RI)
08/ 808,632
February 28, 1997
STATEMENT OF GOVERNMENT RIGHTS This invention was made with government support under grant/contract number DEFG02-86ER45267 awarded by the Department of Energy and grant/contract number DMR-9121747 awarded by the National Science Foundation. The government has certain rights in the invention.