Optical recording medium
 The disclosure describes an optical recording medium for recording, erasing and reading-out information by irradiation a laser beam, comprising: PA1 a lower dielectric protective layer, a phase-change-type recording layer, an upper dielectric protective layer and a metal reflective layer successively deposited on a transparent substrate formed with grooves, in which PA1 both of grooves and lands are used as a recorded region, PA1 a groove depth (d) satisfies the following relation (1): EQU .lambda./7n<d<.lambda./5n (1) PA1 wherein .lambda. represents a wavelength of an irradiation light and n represents a refractive index of the substrate, and PA1 a groove width (GW) and a land width (LW) satisfy the following relation (2): EQU 0.1 .mu.m<GW<LW (2) 
Mitsubishi Chemical Corporation
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Takashi Hironobu Kenichi Michikazu Haruo
Ohno Mizuno Takada Horie Kunitomo