Patent ID: 7842366
Filing Date: 2010-11-30
Classification: G11B,Y10T

Abstract:
1. A multi-layer optical information recording medium comprising four or more information recording layers on which signal information is recorded with any one of information pits whose concave-convex surfaces or phases change and recording marks whose reflectances or phases change, wherein the information recording layers are denoted by the m-th information recording layers, where m is any integer that is 0 or larger, an information recording layer that is farthest from an objective lens of a reproduction optical pickup being denoted by a 0th information recording layer, spacers being interposed between the information recording layers, the spacers being made of a transparent material and having nearly constant thicknesses, wherein when the thickness of the spacer interposed between the m-th information recording layer and an (m+1)th information recording layer is denoted by t where A wherein the crosstalk index (A wherein the intensity reflectances associated with reflective films are due to multiple reflections and decrease in a direction closer to an objective lens, and the differences in thicknesses between the spacers can be decreased in the direction closer to the objective lens based on the decreasing intensity reflectances associated with the reflective films.