Time of Flight Diffraction Method Using Laser Ultrasound for Noncontact Flaw Height Measurement
We developed a laser TOFD (Time of flight diffraction) algorithm which utilizes not only longitudinal wave but also shear wave. This algorithm made it possible to obtain accurate flaw depth without knowing the specimen velocity and probe distance previously. We constructed the laser TOFD system and applied it to estimate the slit depth of aluminum alloy plate. Time of flight of lateral wave, flaw tip diffraction waves and mode converted shear wave at flaw tip were used to estimate the slit depth using new algorithm.
Kikuo Kishimoto, Masanori Kikuchi, Tetsuo Shoji and Masumi Saka
T. Mihara et al., "Time of Flight Diffraction Method Using Laser Ultrasound for Noncontact Flaw Height Measurement", Key Engineering Materials, Vols. 261-263, pp. 987-992, 2004