Directivity measurements in aluminum using a laser ultrasonics system

J. M.S. Sakamoto, Bernhard R. Tittmann, A. Baba, G. M. Pacheco

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

A laser ultrasonics system was setup to measure the directivity (angular dependence pattern) of the amplitude of ultrasonic waves generated in aluminum samples. A pulsed Nd:YAG laser operating at 1064 nm optical wavelength, with typical pulse width (FWHM) of 8 ns, and energy per pulse of 450 mJ, was used to generate the ultrasound waves in the samples. The laser detection system was a Mach-Zehnder interferometer with typical noise-limited resolution of 0.25 nm (rms), frequency range from 50 kHz to 20 MHz, and measurement range from -75 nm/V to +75 nm/V. Two different optical spot sizes of the Nd:YAG laser were used to generate waves in the ablation regime: one was focused and the other was unfocused. Using the obtained data, the directivity graphics were drawn and compared with the theoretical curves, showing a good agreement. The experiments showed the directivity as a function of the optical spot size. For a point ultrasonic source (or focused optical spot), the directivity shows that the longitudinal waves present considerable amplitude in all directions. For a larger ultrasonic source (or an unfocused optical spot) the directivity shows that the longitudinal waves are generated with the higher amplitudes inside angles around ±10°.

Original languageEnglish (US)
Article number012032
JournalJournal of Physics: Conference Series
Volume278
Issue number1
DOIs
StatePublished - Jan 1 2011

Fingerprint

directivity
ultrasonics
aluminum
longitudinal waves
lasers
YAG lasers
rangefinding
Mach-Zehnder interferometers
ultrasonic radiation
ablation
pulsed lasers
pulse duration
frequency ranges
curves
pulses
wavelengths
energy

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Sakamoto, J. M.S. ; Tittmann, Bernhard R. ; Baba, A. ; Pacheco, G. M. / Directivity measurements in aluminum using a laser ultrasonics system. In: Journal of Physics: Conference Series. 2011 ; Vol. 278, No. 1.
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Directivity measurements in aluminum using a laser ultrasonics system. / Sakamoto, J. M.S.; Tittmann, Bernhard R.; Baba, A.; Pacheco, G. M.

In: Journal of Physics: Conference Series, Vol. 278, No. 1, 012032, 01.01.2011.

Research output: Contribution to journalArticle

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