Patent ID: 8740671
Filing Date: 2014-06-03
Classification: C03C,G11B

Abstract:
1. A glass substrate for an information recording medium, the glass substrate comprising: a surface having an arithmetic mean roughness (Ra) deviation rate of 3% or less, wherein the Ra deviation rate is calculated based on arithmetic mean roughness (Ra) values measured using an atomic force microscope at 10 or more different measurement fields on the surface of the glass substrate, each measurement field having 10 μm×10 μm, and wherein the Ra deviation rate is the ratio of the number of measurement fields, each having an Ra value that differs by 0.1 nm or greater relative to a totality mean value of Ra values for all of the 10 or more measurement fields, with respect to the number of the 10 or more measurement fields, each Ra valued being 1.5 nm or less, the surface having a maximum peak height (Rp) of 10 nm or less, and the ratio of Rp/Ra being 10 or less.