SCATTERING BY LACUNARY GRATINGS

The paper is devoted to a theoretical and numerical study of lacunary gratings, namely, gratings where some lines are missing. From a rigoro us electromagnetic theory of scattering by this structure, the limits of validity of three approximate and simple theories are given. These approximate theories are used in order to predict some interesting pro perties of lacunary gratings. Finally, we try to give a quantitative a nswer to the following question: how to detect the lacunary defect rat io from intensity measurements?