Frequency Dependence of Subsurface Flaws Detection Efficiency via The Total Internal Reflection Ultrasonic Sensor

TL;DR

This paper investigates how the frequency of shear waves in a Total Internal Reflection Ultrasonic Sensor affects its ability to detect subsurface flaws, emphasizing the sensor's design and wave behavior.

Contribution

It introduces a specific sensor design utilizing shear horizontal waves and analyzes the frequency dependence of flaw detection efficiency.

Findings

Detection efficiency varies with ultrasonic frequency.

Sensor design effectively isolates shear waves.

Flaw detection sensitivity depends on wave frequency.

Abstract

The Total Internal Reflection Ultrasonic Sensor (TIRUS) is a device especially aimed at detecting subsurface flaws in a tested specimen based on the frustrated total internal reflection of bulk ultrasonic waves in the sensor body [1]. In the fabricated experimental sample of the TIRUS a transducer of the sensor emitted a slow shear wave with the velocity ~600 m/s (SSW) into the [110] direction of the TeO2 crystal (Fig. 1) [2]. The sensor design was such that the displacement vector of the SSW lay in the planes of reflecting surfaces of the crystal, that is, it was a shear horizontal (SH) wave with respect to these planes. It was assumed that with such a design no other waves should exist in the crystal except those polarized as the SSW [3]. The total internal reflection of a probing ultrasonic wave incident at the interface between the sensor and a tested object is frustrated if there is a subsurface flaw in the evanescent field under the interface (Fig. 1, a). As a result, the reflected wave is affected, and the sensor output changes.