Abstract: A new invention for the laser-based generation of ultrasound is described. In conventional laser-based ultrasound, a pulse of light is incident on a solid. The light is converted to heat expanding the material near the surface. This thermoelastic expansion creates an acoustic wave in the material. Detection of the ultrasound allows the nondestructive inspection of the material. The rate of performing an ultrasound scan is inherently limited by the pulse rate of the laser. In this invention, a continuous wave (cw) high-power laser sweeps across the material, using thermoelastic expansion to create an ultrasound wavefront on the surface of and in the material. Detection of the ultrasound wavefront provides evidence of the strength of the material and the presence of defects. With Continuous Laser Generation of Ultrasound, material analysts will be able to perform ultrasound scans potentially hundreds of times faster than the current methods.

Abstract: A new invention for the laser-based generation of ultrasound is described. In conventional laser-based ultrasound, a pulse of light is incident on a solid. The light is converted to heat expanding the material near the surface. This thermoelastic expansion creates an acoustic wave in the material. Detection of the ultrasound allows the nondestructive inspection of the material. The rate of performing an ultrasound scan is inherently limited by the pulse rate of the laser. In this invention, a continuous wave (cw) high-power laser sweeps across the material, using thermoelastic expansion to create an ultrasound wavefront on the surface of and in the material. Detection of the ultrasound wavefront provides evidence of the strength of the material and the presence of defects. With Continuous Laser Generation of Ultrasound, material analysts will be able to perform ultrasound scans potentially hundreds of times faster than the current methods.

Abstract: The investigation, development and application of a laser-based ultrasonic inspection system to the problems of evaluating polymer/graphite composite materials has been realized. The use of lasers to generate and detect ultrasonic waveforms in materials provides a means to detect material properties remotely. The study consisted of three main aspects: 1) A confocal Fabry-Perot (CFP) based system has been devolved which uses light reflected from the CFP interferometer to derive the ultrasonic signal. This allows higher frequency components of the detected waveforms to be discerned when compared to a CFP-based system using light transmitted through the CFP interferometer. 2) Thermoelastic and ablative laser generation of acoustic pulses in polymer/graphite composite materials has been investigated. Thermoelastic generation of ultrasound occurs when thermal energy deposited by a pulsed laser creates a localized expansion in the material.