spectral dependence of the complete permittivity tensor of permalloy thin films has been derived in broad spectral range from 0.7 to 6.4 eV required for theoretical design of novel optoelectronic devices; influence of the surface oxidization on the optical and magneto-optical properties of uncapped nanometer-thick permalloy films have been demonstrated; spectral dependence of polar Kerr magneto-optical effect and its variation with permalloy layer thickness has been demonstrated to be used for fine-tuning experimental parameters or device geometry; influence of the substrate/layer interface to the magneto-optical properties have been demonstrated in 10 nm thick permalloy film.