Patent ID: 8302119

Claim:
An optical information recording medium comprising: at least three information layers; at least two intermediate layers separating the information layers; and a protective layer, wherein the information layers, the intermediate layers and the protective layer are layered upon a substrate, wherein the optical information recording medium is recorded onto and/or reproduced from, from a side of the protective layer using an optical head, wherein a difference between a round-trip optical path length of information light returning to the optical head from one of the information layers upon which recording/reproducing light is focused and a round-trip optical path length of reflected stray light that is a part of stray light (i) reflected by one of the information layers and that returns to the optical head and (ii) having been reflected by the information layer or a surface of the protective layer no more than three times is no less than 2 μm and no more than 146 μm, wherein the round-trip optical path length of the information light is an optical path length from where the information light enters the surface of the protective layer to where the information light exits the surface of the protective layer, and wherein the round-trip optical path length of the reflected stray light is an optical length from where the reflected stray light enters the surface of the protective layer to where the reflected stray light exits the surface of the protective layer.