Random rough surfaces that produce a Lambertian distribution of radiant intensity

The inadequacy of the Kirchhoff approximation and the small-scattering-angle assumption to describe Lambertian rough surfaces is discussed. It is shown, however, that the small-perturbation method based on the extinction theorem recently put forward permits the construction of perfectly conductive, slightly rough surfaces, which produce a Lambertian distribution for the diffuse part of the mean radiant intensity.