A calibration methodology of ultrasonic transducers: Evaluation of spatial propagation characteristics of pulse-echo.

This study aims to develop a novel methodology, a combined system of optical and ultrasonic measurements, for evaluating spatial propagation characteristics of ultrasonic pulse-echo. The system can record pulse-echo profiles except in the near field where the ultrasound is not well-focused. An in-house-developed stereo-vision system is utilized as a reference to measure the three-dimensional coordinates in spherical particle dispersion in water. Ultrasonic pulse-echo from the particles is identified to the three-dimensional coordinates obtained by the stereo-vision system. Acquiring numerous data of randomly-dispersed particles in water gives higher data density in three-dimensional space than the conventional method using a hydrophone sensor. The method realizes a highly-accurate evaluation of the tilt angle of the pulse emission against the transducer casing axis within O (0. 0 1 ∘). The fact that the pulse-echo waveform in the three-dimensional space, rather than the radiation sound pressure field of the conventional method, can be converted into a database is crucial. • A calibration method for the ultrasound transducer is established. • Ultrasound pulse-echo measurement is combined with a stereo-vision system. • The propagation characteristic of ultrasound pulse-echo is measured with high accuracy. • The calibration result is validated by applying velocity profiling of water flow. [ABSTRACT FROM AUTHOR]