  We present measurement and analysis techniques that allow the complete
complex magneto-conductivity tensor to be determined from mid-infrared (11-1.6
micron; 100-800 meV) measurements of the complex Faraday (theta_F) and Kerr
(theta_K) angles. Since this approach involves measurement of the geometry
(orientation axis and ellipticity of the polarization) of transmitted and
reflected light, no absolute transmittance or reflectance measurements are
required. Thick film transmission and reflection equations are used to convert
the complex theta_F and theta_K into the complex longitudinal conductivity
sigma_xx and the complex transverse (Hall) conductivity sigma_xy. theta_F and
theta_K are measured in a Ga_(1-x)Mn_xAs and SrRuO_3 films. The resulting
sigma_xx is compared to the values obtained from conventional transmittance and
reflectance measurements, as well as the results from Kramers-Kronig analysis
of reflectance measurements on similar films.
