Patent ID: 7126905

Claim:
An information recording medium comprising: a transparent substrate having a first surface and a second surface opposite to the first surface; reflectance reduction means provided on the first surface of the transparent substrate; and an information recording layer provided on the second surface of the transparent substrate, wherein portions of light having entered the first surface at an incident angle in the range of 0° to a maximum possible incident angle, which are transmitted through the transparent substrate, are used for recording information to the information recording layer or reproducing information recorded on the information recording layer, the reflectance reduction means reduces a reflectance for the light which enters the first surface at the maximum possible incident angle and is reflected by the first surface, the reflectance reduction means includes a transparent thin film layer, the thickness of the thin film layer is set so as to minimize the reflectance for light, which enters the first surface of the transparent substrate at the maximum possible incident angle and is reflected by the first surface of the transparent substrate, and the index of refraction of the thin film layer is smaller than that of the transparent substrate.