ISSN:
1741-2765
Keywords:
Laser ultrasonics
;
Fabry-Perot interferometer
;
C-scan test
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract A beam-steering C-scan system for laser generation and detection of ultrasound in opaque solids has been developed. For ultrasound detection, the system uses a confocal Fabry-Perot interferometer that is stabilized at its high-sensitivity point by implementing a novel procedure that does not require a reference beam. This stabilization procedure effectively compensates for slowly varying (up to 2 Hz) disturbances and, more important, for any change in the interferometer illumination conditions while probing different scanning points. For the latter reason, the proposed stabilization appears to be more effective than previous approaches for high-sensitivity ultrasound detection in beamsteering scans. Noise performance and sensitivity limit of the system are evaluated. Ultrasonic echoes are detected in aluminum samples having optically rough surfaces with single-pulse generation signal-to-noise ratios on the order of 20 dB. A C-scan inspection is performed where a known defect in the test piece is successfully detected by time-of-flight gating of the ultrasonic signals.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02329813
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