Using the angular spectrum theory and experimental velocity data of surface acoustic waves (SAW) on YZ-LiNbO(3), the focusing characteristics of a circular-arc interdigital transducer have been demonstrated. The calculated results show that the depth of focus is long and the compressed acoustic beam width is very narrow. The concept of a caustic is shown to be an excellent way of characterizing SAW focusing by a circular-arc interdigital transducer on YZ-LiNbO(3). Comparison between theoretical and experimental results shows good agreement.
The two-dimensional diffraction catastrophe forms on an anisotropic substrate are studied. According to the catastrophe theory, they separately belong to fold caustics and cusp ones. The acoustic fields associated with these caustics are also classified into two categories, and can be expressed by the Airy function and the Pearcy function, respectively. The forms of these two kinds of caustics have been determined by these expressions of the acoustic fields. The experimental verifications have been provided by the surface acoustic wave (SAW) field excited by a circular arc interdigital transducer on YZ-LiNbO3. By means of the dark-field method, we have obtained photographs of SAW caustics. The experimental results agree with our theoretical calculations. We have concluded that it is the velocity anisotropy of the substrate that causes these two kinds of caustics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.