| 摘要 |
A ferrofluid ultrasonic signal modulator consisting of a closed hollow member having a transmitting transducer affixed in one end and a receiving transducer affixed in an opposite end. The closed member forms an interferometer chamber in which are placed two immiscible liquids. One of the liquids is a ferrofluid adjacent the receiving transducer and partially filling the chamber and the other is a liquid possessing low attenuation for the ultrasonic waves, filling the remainder of the chamber and in contact with the transmitting transducer. When a magnetic field is applied to the interface formed by the two liquids the path length through the said other liquid between the transmitting transducer and the interface is changed due to distortions produced in the ferrofluid by the magnetic field. This change shifts the resonance spike position in the frequency domain resulting in amplitude modulation of the ultrasonic signal transmitted through the chamber.
|
