Title: Optical method for determining the mechanical properties of a material

Abstract

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.

Inventors:

Maris, Humphrey J ^[1]; Stoner, Robert J ^[2]

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+ Show Inventor Affiliations

1. Barrington, RI
2. Duxbury, MA

Issue Date:

1998-01-01

Research Org.:

Brown Univ., Providence, RI (United States)

OSTI Identifier:

872015

Patent Number(s):

5844684

Assignee:

Brown University Research Foundation (Providence, RI)

Patent Classifications (CPCs):

G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

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G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

G01N29/0681 - {by acoustic microscopy, e.g. scanning acoustic microscopy}
G01N21/1717 - {with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance}
G01N2291/011 - Velocity or travel time
G01N29/2418 - {using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics
G01N2291/0427 - Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
G01N2291/0237 - Thin materials, e.g. paper, membranes, thin films

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DOE Contract Number:  

FG02-86ER45267

Resource Type:

Patent

Country of Publication:

United States

Language:

English

Subject:

optical; method; determining; mechanical; properties; material; disclosed; characterizing; sample; comprising; steps; acquiring; data; probe; beam; wavelength; measure; times; nanoseconds; change; reflectivity; induced; pump; analyzing; determine; property; comparing; background; signal; component; obtained; similar; delay; time; range; samples; prepared; conditions; rise; physical; chemical; measured; dependent; caused; ultrasonic; waves; generated; determined; step; interpolating; reference; obtain; intermediate; set; sound; velocity; density; constants; embodiment; correlation; structural; phase; grain; orientation; stoichiometry; ultrasonic wave; time dependent; waves generated; optical constants; optical method; probe beam; mechanical properties; material properties; data obtained; ultrasonic waves; pump beam; delay time; reference sample; measured time; sound velocity; grain orientation; chemical material; acquiring data; background signal; beam wavelength; /356/