Through-transmission imaging of solids in air using ultrasonic gas-jet waveguides

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 50; no. 11; pp. 1509 - 1515
• Main Authors: Hutchins, D.A., Doowon Choi, Davis, L.A.J., Gan, T.-H., Billson, D.R.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.2003; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic beams; Acoustic imaging; Acoustic transducers; Acoustic velocity; Acoustic waveguides; Acoustical measurements and instrumentation; Acoustics; Attenuation; Beams (radiation); Capacitance; Carbon dioxide; Exact sciences and technology; Ferroelectric materials; Fundamental areas of phenomenology (including applications); Image resolution; Physics; Solids; Transducers; Transduction; acoustical devices for the generation and reproduction of sound; Ultrasonic imaging; Waveguides; Acoustic measurement; Air coupling; Gas jet; Transmission mode; Experimental study; Acoustic image; Acoustic waveguide; Ultrasonic transducer
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2003.1251134

An ultrasonic waveguide has been produced in air by using a gas jet. This uses the fact that a lower acoustic velocity can be produced within the jet, relative to the air surrounding it. The lower velocity is achieved by mixing carbon dioxide with air within the jet at a concentration that is a compromise between lower acoustic velocity and increasing attenuation. Using a capacitance transducer placed within the flowing gas, it is shown that improvements in the beam width can result when the gas jet is used. Air-coupled images of solid samples have been produced in through transmission, which demonstrate that an improved lateral resolution can result when a comparison is made to images from conventional air-coupled testing.