A Methodology for Calibrating Radiation Angle of Ultrasonic Transducer

―Spatial Visualization of Ultrasonic Pulse using Stereo Images―

Abstract

The error evaluation of the ultrasonic radiation angle for the casing axis of the ultrasonic element is a critical calibration parameter for flow velocity measurement technology. To evaluate the radiation angle error of a transducer, measuring the ultrasonic propagation characteristics in three-dimensional space is necessary, but conventional methods have not reached the technical level to evaluate the radiation angle on the order of 0.01°. To improve the measurement time and spatial resolution, which are important issues, in this study, we constructed an evaluation system for the propagation characteristics of pulse echoes emitted from ultrasonic elements. This method collects many ultrasonic waveforms and three-dimensional coordinate information of particles randomly dispersed in water. Spatial visualization using stereo images was used as the three-dimensional coordinate reference value. As a result, we were able to quantitatively evaluate and calibrate the propagation characteristics of the ultrasonic element, such as the central axis and the propagation width of the ultrasonic pulse. Unlike conventional evaluation methods that mainly evaluate sound pressure field measurements, this evaluation method is novel in evaluating the spatial distribution of pulse-echo waveforms, which is unprecedented.