Optical recording medium

Abstract

An optical recording medium has a mask layer 4, an intermediate dielectric layer 5, a recording layer 6, and a reflective layer 8 on a transparent substrate 2. The recording layer 6 contains a recording material which changes its crystallographic structure upon exposure to recording light for recording information. The mask layer 4 contains a mask material which increases its light transmittance when melted and has a complex refractive index (n.sub.0 -ik.sub.0), of which the real part n.sub.0 drops by 1.0 or less and the imaginary part k.sub.0 drops by 0.25-1.0 when the mask material converts from a crystalline state to an amorphous or microcrystalline state. Signals can be reproduced from the medium with high C/N without resorting to reading light of shorter wavelength or an optical pickup objective lens having a larger numerical aperture and even when the linear velocity of the medium relative to recording and reproducing light is low.

Dependencies are inferred from the claim text.