Patent ID: 7484400
Filing Date: 2009-02-03
Classification: G11B,Y10T

Abstract:
1. A method of testing an optical information medium, the method conducting an evaluation test in terms of abrasion resistance on a laser beam incident-side surface of the optical information medium which includes at least a support base, an information recording layer, and a translucent base in that order, to and/or from which recording and/or reproducing is made optically by a laser beam incident on the information recording layer from the translucent base side, and which has a focused radius R of a recording/reproducing laser beam of 40 μm or more and 400 μm or less on the translucent base surface, the focused radius R defined by the following expression (1): (in the expression, T is the thickness (μm) of the translucent base of the optical information medium, NA is the numerical aperture of an object lens in the recording/reproducing device of the optical information medium, and n is the refractive index of the translucent base of the optical information medium), the method comprising: evaluating the abrasion resistance of the laser beam incident-side surface based on an error amount of a reproduction signal after the laser beam incident-side surface has been abraded by abrasive wheels specified in ISO9352.