Patent ID: 8295150
Filing Date: 2012-10-23
Classification: G11B

Abstract:
1. An optical information medium measurement method for measuring a difference in reflectance in an optical information medium having a multilayered structure having a plurality of information layers, the optical information medium measurement method comprising: a first step of obtaining, via a measurement optical system, an apparent reflectance of each respective information layer of the plurality of information layers, such that the apparent reflectance of each respective information layer corresponds to a ratio between a signal light amount and an incident light amount obtained while reproducing information from the respective information layer; a second step of obtaining a thickness between the plurality of information layers of the optical information medium; a third step of obtaining a reflectance of each respective information layer of the plurality of information layers of the optical information medium; and a fourth step of obtaining a result of conversion as a difference in a reflectance of each respective information layer for a standard optical system differing from the measurement optical system, the result of conversion being obtained for each respective information layer from a value indicative of the apparent reflectance of the respective information layer, as obtained in the first step, a value indicative of the thickness between the plurality of information layers, as obtained in the second step, and a value indicative of the reflectance of the respective information layer, as obtained in the third step.