High frequency LiNbO3 focusing transducer using a mechanical dimpling technique

High-frequency focusing LiNbO₃ ultrasonic transducer utilizing the dimpling technique was fabricated and tested. A spherical surface with a curvature radius of 6mm was formed on the front face of the LiNbO₃ plate with the thickness of 80μm. The other surface of the plate remained in flat without any crack. The conductive epoxy was used as the backing material and parylene was deposited on the front face as the matching layer. From the pulse-echo measurement, the center frequency of the focused transducer was 45MHz and the bandwidth was 63%. The insertion loss was -22dB. The transducer has been used for wire phantom imaging. These promising results proved that it´s of great potential to fabricate high frequency broadband focusing ultrasonic transducers based on LiNbO₃ single crystal using the mechanical dimpling process.