The invention relates to a technique of providing illumination light having an even intensity, in order to make intensity of three illumination light with a simple structure. Embodiments enable client reporting and authentication as well as broadcast content encryption. An AlN material includes a first part consisting of a plurality of spheres and a second part consisting of a plurality of slugs. The present invention affords the ability to utilize a majority of the transducer passband for both transmission and reception, and to transmit pulses which are less destructive to microbubble contrast agents.