Adventures in Green's Land: Light Scattering in Anisotropic Media.
CITY COLL NEW YORK DEPT OF PHYSICS
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Since the scattering volume in a crystal in a typical Brillouin scattering experiment using laser excitation is small but finite, solution of the wave equation by a Greens function technique is most convenient. Two things greatly complicate such a calculation 1 the optical anisotropy of the crystal leads to nonspherical wave surfaces even in the far field and to noncollinearity of the propagation and energy flow vectors and 2 detection of the scattered light outside the crystal requires the inclusion of a crystal surface in the radiation problem. Two mutally consistent approaches to this problem are presented. First, a far field Greens function inside the crystal is calculated. The detected power outside the crystal is then calculated from it and the surface coupling factors - solid angle expansion, scattering volume demagnification and transmissivity. Second, a far field Greens function outside the crystal is calculated for several cases. A scattered power formula valid outside the crystal, which applies to crystals of any symmetry and orientation, to any scattering angle, and to fairly general surface orientations, is then presented. Author Modified Abstract