Patent ID: 6537648
Filing Date: 2003-03-25
Classification: G11B,Y10S,Y10T

Abstract:
A substrate for an information recording medium, wherein said substrate is made of a glass, said substrate having a microwaviness average height Raâ€² not greater than 0.05 microinch as measured for measurement points within a measurement region of 50 &mgr;mÃ—50 &mgr;m to 4 mmÃ—4 mm on a surface of said substrate, said microwaviness average height Raâ€² being given by: Raâ€²=1n&it;&Sum;i=1n&it;&LeftBracketingBar;x&it;â€ƒ&it;i-x_&RightBracketingBar;,where xi represents a measurement point value of each measurement point, {overscore (x)} representing an average value of the measurement point values, n representing the number of said measurement points.