The Scanning Laser Source Technique for Detection of Surface-Breaking and Subsurface Defect

Young Hoon Sohn, Sridhar Krishnaswamy

Research output: Contribution to journalArticle

Abstract

The scanning laser source (SLS) technique is a promising new laser ultrasonic tool for the detection of small surface-breaking defects. The SLS approach is based on monitoring the changes in laser-generated ultrasound as a laser source is scanned over a defect. Changes in amplitude and frequency content are observed for ultrasound generated by the laser over uniform and defective areas. The SLS technique uses a point or a short line-focused high-power laser beam which is swept across the test specimen surface and passes over surface-breaking or subsurface flaws. The ultrasonic signal that arrives at the Rayleigh wave speed is monitored as the SLS is scanned. It is found that the amplitude and frequency of the measured ultrasonic signal have specific variations when the laser source approaches, passes over and moves behind the defect. In this paper, the setup for SLS experiments with full B-scan capability is described and SLS signatures from small surface-breaking and subsurface flaws are discussed using a point or short line focused laser source.
Original languageEnglish (US)
Article number41132140
Pages (from-to)246-254
Number of pages9
JournalJournal of the Korean Society for Nondestructive Testing
Volume27
Issue number3
StatePublished - 2007

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