Theory of differential and integral scattering of laser radiation by a dielectric surface taking a defect layer into account

The differential and integral light scattering by dielectric surfaces is studied theoretically taking a thin near-surface defect layer into account. The expressions for the intensities of differential and total integral scattering are found by the Green function method. Conditions are found under which scattering by the defect layer can be neglected compared to scattering by the surface roughness. A method is proposed to separate the scattering from the surface roughness and the defect layer. Estimates are made of the typical changes in the permittivity and scattering intensity which correspond to the defect layer related to the higher concentration of structural defects in the near-surface region.