Location

Brunswick, ME

Start Date

1-1-1997 12:00 AM

Description

Q-switched lasers are often used as a non-contact ultrasound source in non-destructive evaluation (NDE) of materials [1]. Q-switched lasers typically have ns pulse durations and generate broadband ultrasound waves, though longer laser pulses, of 100 microseconds or greater, have also been used [2] for NDE. These longer pulses tend to produce somewhat lower center frequencies than do Q-switched pulses, though they are still a broadband source. But it would be desirable in some NDE applications to narrow the signal bandwidth to improve the signal to noise ration (SNR), and also to have direct control over the center frequency of the generated ultrasound. In principle, this may be achieved by temporal [3,4] or spatial modulation [5,6] of the laser pulse, or both [7]. The purpose of this work was to develop a numerical model of a single, temporally modulated laser source of ultrasound in the thermoelastic regime, for isotropic metals.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

16A

Chapter

Chapter 2: Emerging Inspection Technologies

Section

Laser Based Ultrasonics

Pages

601-607

DOI

10.1007/978-1-4615-5947-4_79

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

A Model of Temporal Intensity Modulation for Laser Generated Ultrasound

Brunswick, ME

Q-switched lasers are often used as a non-contact ultrasound source in non-destructive evaluation (NDE) of materials [1]. Q-switched lasers typically have ns pulse durations and generate broadband ultrasound waves, though longer laser pulses, of 100 microseconds or greater, have also been used [2] for NDE. These longer pulses tend to produce somewhat lower center frequencies than do Q-switched pulses, though they are still a broadband source. But it would be desirable in some NDE applications to narrow the signal bandwidth to improve the signal to noise ration (SNR), and also to have direct control over the center frequency of the generated ultrasound. In principle, this may be achieved by temporal [3,4] or spatial modulation [5,6] of the laser pulse, or both [7]. The purpose of this work was to develop a numerical model of a single, temporally modulated laser source of ultrasound in the thermoelastic regime, for isotropic metals.