Laser generation and air coupled detection of ultrasound were combined to produce a hybrid noncontact and remote ultrasonic technique. The technique is suitable for general testing of a number of structural materials. Using this hybrid technique, guided surface waves were generated to propagate along the flange, tread and rim edge of a railroad wheel. The waves complete one revolution around the circumference of the railroad wheel in 1 ms and interact with surface breaking discontinuities that are present on the various parts of the wheel. The flexibility and remote nature of this technique suggest that wayside testing of wheels on a moving train can be made possible.

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