Patent ID: 7286153
Filing Date: 2007-10-23
Classification: G11B

Abstract:
1. An optical disk medium, comprising: a substrate having a structure of an uneven-like shape on a flat surface; a first reflecting film formed on the substrate and having a surface contoured to the uneven-like shape of the substrate, for reflecting a light having a predetermined wavelength; a resin layer having an uneven-like shape on a flat surface directly formed on the first reflecting film; and a second reflecting film formed on the resin layer and having a surface contoured to the uneven-like shape of the resin layer, for reflecting a light having a predetermined wavelength, wherein the uneven-like shapes of the first and second reflecting films represent information, respectively, and wherein a construction arrangement of the optical disk medium satisfies an expression of, where λ is a wavelength of the light irradiated on the optical disk for reproducing information; NB is a refractive index of the substrate; NAF is a numerical aperture of the optical system for converging the light; and Δd is a displacement of optical axes of the first and second reflecting films from a predetermined reference surface where a spherical aberration becomes substantially zero.