Magneto-optical recording medium and writing and readout method therefor
AssigneeMitsubishi Chemical Corporation
InventorsKyuuya Narita, Toshifumi Kawano, Hideharu Takeshima, Masanobu Hodohara
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Abstract
A magneto-optical recording medium having a writing layer formed on a transparent substrate provided with a groove having a flat bottom surface and a flat land, so that writing or readout is carried out on either the groove or the land only by irradiating a laser beam from the substrate side, wherein the sum (.alpha.+.beta.) of a phase shift .alpha. of a reflected light of a readout beam by the substrate and a phase shift .beta. thereof by a layer structure on the transparent substrate, is made to have an opposite sign to a phase shift .gamma. by interference of reflected lights from the groove and the land.
Claims14
A magneto-optical recording medium having a writing layer formed on a transparent substrate provided with a groove having a flat bottom surface and a flat land, so that writing or readout is carried out on either the groove or the land only by irradiating a laser beam from the substrate side, wherein the sum (.alpha.+.beta.) of a phase shift .alpha. of a reflected light of a readout beam by the substrate and a phase shift .beta. thereof by a layer structure on the transparent substrate, is made to have an opposite sign to a phase shift .gamma. by interference of reflected lights from the groove and the land.
A writing and readout method for a magneto-optical recording medium having a writing layer formed on a transparent substrate provided with a groove having a flat bottom surface and a flat land, wherein writing is carried out on either the groove or the land only, and the sum of a phase shift of a reflected light by a layer structure on the transparent substrate and a phase shift of a reflected light by the substrate, is made to have an opposite sign to a phase shift by interference of reflected lights from the groove and the land, and wherein a readout laser beam is used which satisfies Wa.ltoreq.S, where Wa is the width of the flat portion of the groove or the land on which writing is carried out, and S is the diameter in a radial direction of the spot of a readout laser beam (here the spot is meant for an area with at least 1/e.sup.2 of the peak intensity of the laser beam).
A magneto-optical recording medium having a writing layer formed on a substrate provided with a groove having a flat bottom surface and a flat land, so that writing or readout is carried out on either the groove or the land only by irradiating a laser beam from the writing layer side, wherein a phase shift .beta. of a reflected light of a readout beam by a layer structure on the substrate, is made to have an opposite sign to a phase shift .gamma. by interference of reflected lights from the groove and the land.
A writing and readout method for a magneto-optical recording medium having a writing layer formed on a substrate provided with a groove having a flat bottom surface and a flat land, wherein writing is carried out on either the groove or the land only, and a phase shift of a reflected light by a layer structure on the substrate, is made to have an opposite sign to a phase shift by interference of reflected lights from the groove and the land, and wherein a readout laser beam is used which satisfies Wa.ltoreq.S, where Wa is the width of the flat portion of the groove or the land on which writing is carried out, and S is the diameter in a radial direction of the spot of a readout laser beam (here the spot is meant for an area with at least 1/e.sup.2 of the peak intensity of the laser beam).
Dependencies are inferred from the claim text.