Patent ID: 6877343

Claim:
A method of manufacturing a glass substrate for an information recording medium, comprising the steps of: polishing, as a first polishing step, said glass substrate by using a first polishing liquid including a first polishing grain, the first polishing grain having a first grain size between 1 and 3 μm; polishing, as a second polishing step, said glass substrate by using a second polishing liquid including a second polishing grain, the second polishing grain having a second grain size between 0.5 and 2 μm; and polishing, as a third polishing step, said substrate by using a third polishing liquid including a third polishing grain, the third polishing grain having a third grain size of 0.5 μm or less, wherein after said third polishing step said glass substrate has surface roughness which is specified by Rmax and Ra, and Rmax/Ra is greater than 10 but less than or equal to 30, where Ra is representative of a center-line mean roughness and Rmax is defined as a maximum height representative of a difference between a highest point and a lowest point.