Investigation of fabricated 1 MHz lithium niobate transfer standard ultrasonic transducer

Abstract

The fabrication of a single element transducer made from Lithium Niobate (LiNbO3) operating at 1 MHz is focused on this paper. The air-backed LiNbO3 transducer is developed to be used as the standard transfer ultrasonic transducer to calibrate the ultrasound power-meter, which is measured the total emitted acoustic power radiated from the medical equipment. To clarify the precision of the acoustic power, the primary standard calibration measurement (radiation force balance, RFB) based on IEC 61161 is used to investigate the fabricated transducer. The geometry of the piezoelectric active element was first designed by the prediction of Krimholtz, Leedom, and Matthaei (KLM) simulation technique. The electrical impedance measurements of the LiNbO3 element, before and after assembling into the transducer, were checked and compared. The results of electrical impedance show that the operating frequency is in the range from 1 MHz to 10 MHz by forming harmonics. The evaluations of total emitted power and radiation conductance of fabricated transducer were also revealed. Results of acoustic power have been responding up to 2.1 W, which can be assessed within 6% of expanded uncertainty (k = 2).