  Magnetic Raman scattering in two-leg spin ladder materials and the
relationship between the anisotropic exchange integrals are analyzed by P. J.
Freitas and R. R. P. Singh in Phys. Rev. B, {\bf 62}, 14113 (2000). The angular
dependence of the two-magnon scattering is shown to provide information for the
magnetic anisotropy in the Sr_14Cu_24O_41 and La_6Ca_8Cu_24O_41 compounds. We
point out that the experimental results of polarized Raman measurements at
arbitrary angles with respect to the crystal axes have to be corrected for the
light ellipticity induced inside the optically anisotropic crystals. We refer
quantitatively to the case of Sr_14Cu_24O_41 and discuss potential implications
for spectroscopic studies in other materials with strong anisotropy.
