| 摘要 |
A device for ultrasound radiation into a material comprises a piezoelectric substrate, a first input interdigital transducer, a second input interdigital transducer, an output interdigital transducer, an amplifier, and a voltage controller. All the interdigital transducers are formed on one end surface of the piezoelectric substrate. If an input electric signal is applied to the first input interdigital transducer, a first elastic wave is excited in the piezoelectric substrate. A non-leaky component of the first elastic wave is transmitted to the output interdigital transducer, and detected at the output interdigital transducer as a delayed electric signal, which is amplified via the amplifier. A signal part of an amplified electric signal is fed back to the first input interdigital transducer, again. A remaining signal part of the amplified electric signal is applied to the second input interdigital transducer via the voltage controller, where a voltage of the remaining signal part is controlled, In this time, a second elastic wave is excited in the piezoelectric substrate. A leaky component of the second elastic wave is radiated effectively in the form of a longitudinal wave, by an intensity corresponding to the voltage of the remaining signal part, into a material kept in contact with the other end surface of the piezoelectric substrate.
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