Photorefractive Ultrasonic Sensor for Weld Quality MonitoringReport as inadecuate




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We report on a laserultrasonic receiver based on two wave mixings in two nonlinearBi12SiO20 BSO photorefractive crystalsand its application for welded joints inspection. The nonlinear photorefractive crystals are operated with inverted voltages in respect to eachother. Reversal of the voltage inverts the polarity of detected ultrasonicpulses which are generated by a pulsed laser on a sample surface. Present noiseis, however, not inverted. Subtracting both signals after the twophotorefractive crystals using a balanced photo-detector leads to suppressionof noise and to an increase in the signal-noise ratio. We demonstrate theworking principle by using a phase modulator and present laser ultrasonicmeasurement and compare the results from the proposed technique with aconventional two wave mixing interferometer based on single BSO crystal showingthat the signal to noise-rate is significantly enhanced. Finally, we show theexperimental results of application of these detectors for defects detection intwo industrial samples with welded area.

KEYWORDS

Photorefractive Crystal, Laser Ultrasonic, Weld Joints, Defect

Cite this paper

Zamiri, S. , Salfinger, M. , Gruber, M. , Stückler, M. and Reitinger, B. 2017 Photorefractive Ultrasonic Sensor for Weld Quality Monitoring. Open Access Library Journal, 4, 1-11. doi: 10.4236-oalib.1103597.





Author: S. Zamiri*, M. Salfinger, M. Gruber, M. Stückler, B. Reitinger

Source: http://www.scirp.org/



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