Assessment of Axial Sound Field in Air-Coupled Ultrasonic Transducers via Laser Tomography

Air-coupled ultrasonic transducers, renowned for their non-contact, non-invasive, and completely non-destructive properties, have a wide range of applications in non-destructive testing, particularly in aerospace composite materials and porous materials. The study of axial sound field reconstruction in these transducers is critical as parameters such as near-field length and directionality significantly impact resolution, anti-interference capability, and positioning accuracy in non-destructive testing applications. Laser tomography, with its advantages of high spatial resolution, broad frequency range, and non-invasive sound field mapping, presents a promising approach for sound field reconstruction. However, its application has been predominantly focused on radial sound field characterization, with limited and incomplete exploration in the axial sound field domain. This research conducts a comprehensive investigation into the axial sound field distribution of air-coupled ultrasonic transducers from theoretical, simulation, and experimental perspectives using laser tomography. The study reveals a high degree of consistency between experimental results and simulations. Additionally, the research contrasts these findings with axial sound field measurements obtained via traditional microphone methods, validating the efficacy of laser tomography for accurate reconstruction of the axial sound field in air-coupled transducers. These results are invaluable for enhancing the measurement accuracy of the axial sound field in air-coupled transducers and contribute significantly to their design and calibration.