### ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

## 2aSA2. On the scattering cross section of bodies in inhomogeneous medium.

**Yueping Guo
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*Dept. of Ocean Engineering, MIT, Cambridge, MA 02139
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A theorem is proven that relates the scattering cross section of
arbitrarily shaped scatterers to the scattered far field in one or two
particular directions. This can be regarded as a generalization of the
classical optical theorem (also known as the extinction theorem) for
homogeneous medium of infinite extent. In that case, the scattering cross
section is given by the far field in the forward scattering direction. For a
half-space with a bounding surface of arbitrary mechanical properties, it is
shown that the scattering cross section is given by the scattered far field in
the specular reflection direction. For an inhomogeneous medium with abrupt
density and sound-speed change at an interface, the scattering cross section is
given by the far field in both the specular reflection direction and the
transmission direction that obeys the Snell's law. [Work supported by ONR.]