A note on multilayer acoustic antireflection coatings

Abstract As is well known, multilayer structures can be used as wide-band acoustical antireflection (AR) coatings. An investigation has been made of new approaches to the acoustical AR properties of multilayers based on optical techniques. We first present some results from standard acoustical theory as background. Then the use of symmetric multilayers is considered, the analogue of optical symmetric multilayers. Subsequently, characteristic matrices, a commonly used approach in optics, is applied to quarter- and half-wave layers to calculate acoustical AR properties. It is concluded that optical techniques provide a very useful approach to the design of acoustical AR coatings, which can be used to improve ultrasonic transducer performance.