Remote Ultrasonic Classification of Fluids Using the Acoustic Resonance Characteristics of the Container
LOS ALAMOS NATIONAL LAB NM
Pagination or Media Count:
A novel technique for classifying fluids in sealed, metal containers at large stand-off distances has been developed. It utilizes a recently constructed air-coupled acoustic array to excite the resonance vibrations of fluid-filled vessels. The sound field from the array is constructed by transmitting a high frequency modulated carrier wave which is parametrically sell-demodulated along its propagation path in air. The array has a narrow beam width and an operating bandwidth of greater than 25 kHz. The vibrations are detected using a laser vibrometer in a monostatic configuration with the acoustic source. Experiments demonstrate resonance classification of the fluid-filler inside steel vessels is possible with incident sound pressure levels of the demodulated wave as low as 80 dB at the container location. Preliminary experiments demonstrate stand-off distances of greater than 3 m.