Calibration of Imaging Systems by Means of Spherical Targets

  • Michel Auphan
  • Roger H. Coursant
  • Claude Méquio
Part of the Acoustical Imaging book series (ACIM, volume 10)


The problem of calculating the impulsive signal scattered on a target of spherical symmetry, when directivity functions of both transmitting and receiving transducers are known, is mathematically expressed.

In cases where the rigid spherical target is not very small, computations of the received signal become difficult because we deal with quotients of ill-conditioned polynomials. But as these polynomials have integral coefficients and particular properties, a solution has been found on condition of a frequency limitation of the signal.

An experimental set up has been built in order to drop the ball. The echo on the falling ball is then recorded by means of a storage oscilloscope. Various ball diameters have been used and results are compared with the computerized curves. The discrepancy is within the relatively large experimental errors. They are mainly due to the non piston-like behaviour of transducers and to the assumption of a rigid target (Rayleigh surface waves on the ball are neglected).


Rayleigh Wave Inverse Fourier Transform Storage Oscilloscope Integral Coefficient Straight Vertical Line 
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Copyright information

© Plenum Press, New York 1982

Authors and Affiliations

  • Michel Auphan
    • 1
  • Roger H. Coursant
    • 1
  • Claude Méquio
    • 1
  1. 1.Laboratoires d’Electronique et de Physique AppliquéeLimeil-BrévannesFrance

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