Precision laser-ultrasonic velocity measurement and elastic constant determination

Thickness and grain size monitoring in seamless tube-making process using laser ultrasonics

“…The cross-correlation technique, an optimal matched-filter, traditionally uses two successive echoes in the signal and has shown success in determining precise TOF with sufficiently high SNR of the second echo [7]. Such a second echo may be too weak in laser-ultrasonic signals from hot seamless steel tubes.…”

Laser-based excitation of nonlinear solitary waves in a chain of particles

“…Laser ablation is generated when the laser's power density is high, or when the surface of the illuminated medium is covered with a film of water or gel. In this case, the rapid vaporization (ablation) of the film at the surface, or the melting of a small portion of the medium's surface, induces high reaction pressures that can be considered similar to normal stress loading [21][22][23]. Picosecond light pulses have also been used to generate very short stress waves in films of different materials via thermal expansion [24].…”

Flexible metallic ultrasonic transducers for structural health monitoring of pipes at high temperatures

“…Because a sampling rate of 100 MHz was used in the experiment, with the use of the cross correlation method and taking into account interpolation [24], the time measurement error, which may be additionally introduced, was estimated to be at an upper limit of 2 ns. The total uncertainty in time delay measurement was therefore estimated at 4.66 ns.…”