Laser-generated ultrasound: its properties, mechanisms and multifarious applications

The laser generation of ultrasound in solids is reviewed with particular emphasis on the application of this unique ultrasonic source. Three regimes for the generation of ultrasound in solids using lasers in the visible near infrared wavelength region exist: thermoelastic, plasma and constrained surface source regimes. The mechanism for ultrasonic generation in each of these regimes is given. Recent experimental investigations into laser-generated ultrasound are also described, including a description of a different mechanism for the generation of ultrasound in solids using a CO₂ laser. Finally, the many applications of laser-generated ultrasound are reviewed. These applications range from nondestructive testing to the determination of candle flame parameters. Possible future applications are also outlined.