Vector diffraction of a grating with conformal thin films

Vector diffraction theory is appropriate whenever the dimensions of the diffracting structures are comparable with the wavelength of the incident light in order to account correctly for polarization effects. If a periodic groove or pit array is coated with a conformal thin-film stack, the diffracting properties of the substrate may be substantially altered. A computationally efficient vector diffraction model for conformal thin films on a biaxial grating is described that does not require coordinate transformations of Maxwell's equations. Calculated results are compared with other published work on diffraction anomalies and with experimental measurements on a rewritable optical disk. (C) 1996 Optical Society of America.