Air – coupled ultrasonic transducers with collimators

Abstract

Air – coupled planar ultrasonic transducers with collimators can be effectively used for a wide range of distances when air-coupled focussed transducers are being exploited only at the fixed distance. On the other hand use of attached collimators on the planar transducers allows choosing a relatively wide range of spatial resolutions, what is very important for NDT applications. In this paper investigations of influence of collimators having different diameters of apertures on the width of an ultrasonic beam are presented. The investigations were carried out numerically and experimentally. Experimental investigations of dependence of the width of the ultrasonic beam on a diameter of the collimators were carried out. The experimental investigations were performed using a pair of planar 500 kHz air – coupled ultrasonic transducers.