Ultrasonic tomography is a technique by which cross-sectional images of acoustic properties may be formed using measurements made only at the periphery of the area of interest. Various tomographic imaging algorithms based on the Fourier slice technique, algebraic reconstruction technique (ART), and simultaneous iterative reconstruction technique (SIRT) may be used to reconstruct images of sound speed variation and other acoustic properties using a straight ray approximation. The Ultrasonics Research Group has a particular interest in imaging temperature and flow phenomena in gases using capacitive ultrasonic transducers.
The images on the right show how ultrasonic tomography was used to image the temperature of air at different heights above a heat source using capacitive ultrasonic transducers. Parallel-beam scanning with a modified Filtered Back-projection algorithm was used, and the reconstructed temperature distributions were within 5% of those recorded by a digital thermocouple. Similar images of air flow velocity were also obtained above an air jet using the same techniques.
- W. M. D. Wright, P. Ingleby and I. J. O'Sullivan, "Air-coupled through-transmission fan-beam tomography using divergent Capacitive Ultrasonic Transducers (CUTs)", IEEE Trans. Ultrason. Ferroelec. Freq. Contr., Vol. UFFC-52, No. 12, pp. 2384-2394 (2005)
- T. H. Gan, D. A. Hutchins, P. W. Carpenter and W. M. D. Wright, "Simultaneous reconstruction of flow and temperature cross-sections in gases using acoustic tomography", J. Acoust. Soc. Am., Vol. 114, No. 2, pp. 759-766 (2003)
- W. M. D. Wright and I. J. O’Sullivan, "Fan-Beam Tomography of Air Flow in Pipes using an Electrostatic Ultrasonic Transducer Array", Proc. 2002 IEEE Ultrasonics Symposium, pp. 696-699 (2003)
- I. J. O’Sullivan and W. M. D. Wright, "Ultrasonic tomographic imaging of air flow in pipes using an electrostatic transducer array", Review of Progress In Quantitative NonDestructive Evaluation, Vol. 22A, Bellingham, Washington 2002, pp. 666-673 (2003)
- P. Ingleby and W. M. D. Wright, "Ultrasonic imaging in air using fan-beam tomography and electrostatic transducers", Ultrasonics, Vol. 40, No. 1-8, pp. 507-511 (2002)
- W. M. D. Wright, D. W. Schindel, D. A. Hutchins, P. W. Carpenter and D. P. Jansen, "Ultrasonic tomographic imaging of temperature and flow fields in gases using air-coupled capacitance transducers", J. Acoust. Soc. Am., Vol. 104, No. 6, pp. 3446-3455 (1998)