Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Patent
1995-01-24
1996-08-20
Chilcot, Richard
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
73762, G01M 900, G01L 124
Patent
active
055468110
ABSTRACT:
A method for determining the residual stress in an unsupported region of a thin film. The method includes the steps of (a) optically exciting the film with a spatially and temporally varying optical excitation field to launch counter-propagating acoustic modes along at least one wavevector; (b) diffracting a portion of an optical probe field off the excited acoustic modes to generate a time-dependent signal field at the excitation wavevector; (c) detecting the signal field to generate a time-dependent, light-induced signal; (d) analyzing the light-induced signal to determine the frequencies of the acoustic modes; (e) partially determining the dispersion of at least one mode; and, (f) comparing the measured dispersion to that calculated using a mathematical model to allow the residual stress properties of the unsupported region of the film to be determined.
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Nelson Keith A.
Rogers John A.
Chilcot Richard
Massachusetts Instittue of Technology
Noori Max
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