A novel thermosonic imaging system for non-destructive testing

Thermosonic infrared (Sonic IR) imaging is a new non-destructive testing (NDT) technique that uses high-frequency sonic excitation together with infrared (IR) detection to image surface and subsurface defects. A conventional Sonic IR imaging system employs an ultrasonic welder, which is designed to operate at a single frequency. This single frequency ultrasonic source has been found to yield a “blind zone” for NDT due to the formation of standing waves inside the test piece. To overcome this limitation, a spring loaded ultrasonic transducer was used to generate the desired multi-frequency acoustic chaos in the test object [1]. The limitation of the spring loaded ultrasonic transducer is its repeatability and reproducibility for field applications. In this work, we present the development of a novel thermosonic imaging system, which is capable of exciting the ultrasonic transducer at difflerent frequencies for thermosonic NDT to overcome the limitations associated with a single frequency power source as we...