  We study light scattering by a hedgehog-like and linear disclination
topological defects in a nematic liquid crystal by a metric approach. Light
propagating near such defects feels an effective metric equivalent to the
spatial part of the global monopole and cosmic string geometries. We obtain the
scattering amplitude and the differential and total scattering cross section
for the case of the hedgehog defect, in terms of the characteristic parameters
of the liquid crystal. Studying the disclination case, a cylindrical partial
wave method is developed. As an application of the previous developments, we
also examine the temperature influence on the localization of the diffraction
patterns.
