Longitudinal wave precursor signal from an optically penetrating thermoelastic laser source

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6928577

Conant, R J; Telschow, K L

The thermoelastic laser ultrasonic source depends on the optical absorption of energy at the sample surface to produce a volumetric expansion. This paper presents the results of calculations and measurements on the effects of optical penetration of the laser beam into the sample and the elastic waveforms produced. A central result is prediction of a sharp longitudinal waveform that precedes the main waveform and is very similar to that observed with an ablative source (normal point force). The shape of this precursor signal is strongly dependent on the optical penetration depth of the material. A basic explanation of the origin of the precursor signal is given in terms of a one-dimensional model using point sources imbedded within the material. Experimental measurements on a material with a substantial optical penetration depth directly confirm calculations using 2-D integral transform techniques by taking into account the temperature variation with depth. 5 refs., 6 figs.

• Research Organization: EG and G Idaho, Inc., Idaho Falls (USA)
• DOE Contract Number: AC07-76ID01570
• OSTI ID: 6928577
• Report Number(s): EGG-M-88130; CONF-880760-2; ON: DE88016950
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420500* -- Engineering-- Materials Testing
ACOUSTIC TESTING
CHEMICAL ANALYSIS
CRYSTAL STRUCTURE
DATA
ELASTICITY
ELECTROMAGNETIC RADIATION
INFORMATION
LASER RADIATION
MATERIALS TESTING
MECHANICAL PROPERTIES
MICROSTRUCTURE
NONDESTRUCTIVE ANALYSIS
NONDESTRUCTIVE TESTING
NUMERICAL DATA
ONE-DIMENSIONAL CALCULATIONS
RADIATION ABSORPTION ANALYSIS
RADIATIONS
SOUND WAVES
TENSILE PROPERTIES
TESTING
THERMOELASTICITY
TWO-DIMENSIONAL CALCULATIONS
ULTRASONIC TESTING
ULTRASONIC WAVES
WAVE FORMS