Comments on the evaluation of the irradiance of reflected light from rough surfaces

A recent communication provided numerical calculations of the simplified scattering integral and concluded that analytical approximations of this integral were valid only when a parameter Q was much less than unity. It is demonstrated that this conclusion is false and that the correct application of the approximate methods is determined primarily by the product of the wavenumber and the height deviation. The numerical calculations responsible for the erroneous conclusion are shown to be dominated by the coherent scattering component.