skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Ultrasonic Wave Generation by Lasers on Different Metal Surfaces

Abstract

Ultrasonic wave generation by short pulsed laser is revisited in this paper with new experimental work. The generation laser pulse is fiber delivered and a virtually uniform intensity spot is obtained. Ultrasonic pulse strength versus laser pulse energy is obtained for various aluminum and steel surface conditions. To have a better reproducibility, the sample moves after each measurement in order to have a fresh surface for each laser shot. Results show a strong effect of the surface condition. Special attention is paid to the frequency dependence of the generated ultrasonic waves for different laser intensities. The problem of the optimum spot size for a given laser pulse energy is also discussed.

Authors:
;  [1]
  1. Industrial Materials Institute, National Research Council of Canada, Boucherville, Quebec, J4B 6Y4 (Canada)
Publication Date:
OSTI Identifier:
21054960
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 894; Journal Issue: 1; Conference: Conference on review of progress in quantitative nondestructive evaluation, Portland, OR (United States), 30 Jul - 4 Aug 2006; Other Information: DOI: 10.1063/1.2717975; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALUMINIUM; FIBERS; FREQUENCY DEPENDENCE; LASER RADIATION; PULSES; STEELS; SURFACES; ULTRASONIC TESTING; ULTRASONIC WAVES

Citation Formats

Kruger, S. E., and Lord, M. Ultrasonic Wave Generation by Lasers on Different Metal Surfaces. United States: N. p., 2007. Web. doi:10.1063/1.2717975.
Kruger, S. E., & Lord, M. Ultrasonic Wave Generation by Lasers on Different Metal Surfaces. United States. doi:10.1063/1.2717975.
Kruger, S. E., and Lord, M. Wed . "Ultrasonic Wave Generation by Lasers on Different Metal Surfaces". United States. doi:10.1063/1.2717975.
@article{osti_21054960,
title = {Ultrasonic Wave Generation by Lasers on Different Metal Surfaces},
author = {Kruger, S. E. and Lord, M.},
abstractNote = {Ultrasonic wave generation by short pulsed laser is revisited in this paper with new experimental work. The generation laser pulse is fiber delivered and a virtually uniform intensity spot is obtained. Ultrasonic pulse strength versus laser pulse energy is obtained for various aluminum and steel surface conditions. To have a better reproducibility, the sample moves after each measurement in order to have a fresh surface for each laser shot. Results show a strong effect of the surface condition. Special attention is paid to the frequency dependence of the generated ultrasonic waves for different laser intensities. The problem of the optimum spot size for a given laser pulse energy is also discussed.},
doi = {10.1063/1.2717975},
journal = {AIP Conference Proceedings},
number = 1,
volume = 894,
place = {United States},
year = {Wed Mar 21 00:00:00 EDT 2007},
month = {Wed Mar 21 00:00:00 EDT 2007}
}
  • The propagation of ultrasonic waves in stainless steel weld metal, an anisotropic medium, is examined. Significant variations in ultrasonic velocity as well as in attenuation have been observed for different propagation directions. Elastic-constant data have also been acquired from single crystals of stainless steel and used in a simple model to describe the weld metal. From this model, velocities, of sound as well as beam deviations can be predicted. The effect of anisotropy on flaw detection in stainless steel welds is discussed and examples are given. The current work is compared with recent literature on this subject.
  • Recent experiments with unprecedented spatial and temporal resolutions are beginning to provide us with a direct, microscopic understanding of the mechanisms and dynamics of reactions at metal surfaces. It is found that a unified picture can be used to describe desorption of molecules from a metal surface by conventional heating, radiation from a femtosecond laser, and current from the tip of a scanning tunneling microscope. By adjusting the excitation source, control of the reaction pathways and product yields can be achieved. 43 refs., 13 figs., 1 tab.
  • Measurements of damage to metal surfaces induced by intense nanosecond pulses of IR radiation are reported. Single-shot damage thresholds of Cu, stainless steel, molybdenum, and aluminum surfaces have been measured for various angles of incidence and the predicted increase in damage thresholds for grazing incidence optical components have been experimentally verified for the first time at 10 ..mu..m. In addition, multiple-shot damage tests have been performed and practical lifetime curves for Cu mirrors have been established. The results are compared with existing theoretical models and shown to be in general agreement.
  • A coupled pair of nonlinear parabolic equations was derived by Zabolotskaya [1] that model the transverse components of the particle motion in a collimated shear wave beam propagating in an isotropic elastic solid. Like the KZK equation, the parabolic equation for shear wave beams accounts consistently for the leading order effects of diffraction, viscosity and nonlinearity. The nonlinearity includes a cubic nonlinear term that is equivalent to that present in plane shear waves, as well as a quadratic nonlinear term that is unique to diffracting beams. The work by Wochner et al. [2] considered shear wave beams with translational polarizationsmore » (linear, circular and elliptical), wherein second-order nonlinear effects vanish and the leading order nonlinear effect is third-harmonic generation by the cubic nonlinearity. The purpose of the current work is to investigate the quadratic nonlinear term present in the parabolic equation for shear wave beams by considering second-harmonic generation in Gaussian beams as a second-order nonlinear effect using standard perturbation theory. In order for second-order nonlinear effects to be present, a broader class of source polarizations must be considered that includes not only the familiar translational polarizations, but also polarizations accounting for stretching, shearing and rotation of the source plane. It is found that the polarization of the second harmonic generated by the quadratic nonlinearity is not necessarily the same as the polarization of the source-frequency beam, and we are able to derive a general analytic solution for second-harmonic generation from a Gaussian source condition that gives explicitly the relationship between the polarization of the source-frequency beam and the polarization of the second harmonic.« less