Patent ID: 7102990

Claim:
An optical information-recording medium comprising: (a) a disk-shaped substrate having a first main surface and an a second main surface opposite to the first main surface; an incidence surface of the medium being located to be nearer to the first main surface than the second main surface; (b) a recording layer formed on the substrate; and (c) a signal generation layer formed on the substrate in such a way as to be nearer to the incident surface than the recording layer; the signal generation layer allowing an incident light beam irradiated to the incidence surface to pass through and allowing a reflected light beam from the recording layer to pass through; the signal generation layer including a transmittance changing region; the transmittance changing region having a transmittance with respect to the incident light beam different from its neighborhood, thereby generating a repeated transmittance change according to rotation of the medium, wherein the recording layer has a multilayer structure comprising a lower protection sublayer, a magneto-optical recording sublayer, an upper protection sublayer, and a metal reflection sublayer; and wherein the recording layer is formed on the first main surface of the substrate while the signal generation layer is formed on the second main surface of the substrate.