| 摘要 |
<p>Ultrasonic transducer comprises a body which is activated to produce ultrasonic vibrations at one wavelength. At least one sound-reflecting surface has lamda/4 layer of which the acoustic impedance lies between that of the body and that of the sound-propagating medium, where lambda is the wavelength of the ultrasound in the lambda/4 layer. The layer pref. consists of SiO2 hollow spheres and polystyrene, or SiO2 hollow spheres and epoxy resin, and has an acoustic impedance of Cs KcL L)%, where c is the sound velocity and is the density, and the index K denotes the body, the index s dnotes the lambda/4 and the index L denotes the propagating medium. The transducer has a wider bandwidth, greater sensitivity when used as a microphone, and increased efficiency.</p> |
