Thermography with excitation by elastic waves: comparison of techniques (pulse, burst, lockin)

Ultrasound thermography or sonic thermography is being used for defect-selective imaging where the background of intact structures is suppressed. This concept is helpful in terms of reliability and speed of inspection. However, as compared to optical excitation the method implies high power ultrasound injection, which is a considerable load on the inspected structure. Hence one needs to consider which technique provides which information at which load. Our paper discusses these topics on the base of various examples. 1