| 摘要 |
PURPOSE:To enable adjusting of a depth of focus, by mounting a sensor for transmitting and receiving an ultrasonic focusing beam, a means for two-dimentionally and relatively scanning within a focusing area of a beam, and a means for switching the value of the depth of focus of the sensor. CONSTITUTION:A lower electrode 205 is deposited to one end surface of a lens material 200, and a piezo-electric film such as ZnO is deposited thereon. Two concentrical circular upper electrodes 230 and 210 are further formed thereon, and electric input terminals 250 and 240 are placed thereon, respectively. If a RF electric pulse signal is simultaneously applied to the terminals 240 and 250, a flat ultrasonic pulse 260 is generated and is focused to a focus F. A potential angle Q1 of a lens diameter, based on the current focus F, decides a F number, and is found from F=1/2sintheta1. If the F number if 0.7, theta1 is equal to 45 deg.. If the FR electric signal is applied to only the terminal 250, the F number attains 2.2 in a similar manner in the case of Q2=13 deg.. |
