Dynamic focusing of an ultrasonic be am by means of a phased annular array using a pulse technique

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Authors

  • Tamara KUJAWSKA Institute of Fundamental Technological Research Polish Academy of Sciences, Poland

Abstract

An approach to compute, the transient radiation resulting from an impulse velocity motion of an array of annular pistons in a rigid planar infinite baffle is presented. The approach is limed on developing the expression for an impulse response function, which is the time-dependent velocity potential at a spatial point resulting from an impulse velocity of a piston. The time-dependent pressure for any piston velocity motion may then be computed by a convolution of the piston velocity with the appropriate impulse response. Numerical results of near field time-dependent radiation from annular phased array are discussed for pulsed velocity conditions. The lateral acoustical pressure distribution at different field depths is shown. The ultrasonic beam-width as a function of the depth for every focal zone is also presented. Obtained results were compared with corresponding dependences for steady states.

References

[1] A. A. KHARKEVICH, Neustanovivshyesya volnovye wyavlenya, Gosudarstvennoe Izdatelstvo Techniko-teoreticheskoy Literatury, Moscow 1950.

[2] J. ETIENNE, L. FILIPCZYŃSKI, A. FIREK, J. GRONIEWSKI, J. KRETOWICZ, G. ŁYPACEWICZ, J. SAŁKOWSKI, In vivo measurements of the intensity of a focused ultrasonic beam used in ultrasonography of early pregnancy (in Polish), Archiwum Akustyki, 11, 1 (1976).

[3] L. FILIPCZYŃSKI, Radiation of acoustic waves for pulse ultrasonic defectoscopy (in Polish), Proc. IT Conference on Ultrasound of Polish Academy of Sciences, PWN, Warsaw 1957.

[4] L. FILIPCZYŃSKI, I. ROSZKOWSKI, Ultrasonic diagnostics in gynaecology and obstetrics (in Polish), PZWL, Warsaw 1977.

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