GLASS MASTER DISK FOR OPTICAL DISK MASTER

摘要

PURPOSE:To allow easy visual checking of whether the reuse of the glass master disk body is still possible or not by providing a recess having a prescribed depth to the part on one surface side of the master disk exclusive of the part where patterns are formed. CONSTITUTION:One piece of the recess 3 of an arbitrary shape having the prescribed depth is provided to the part of the one surface of the glass master disk 1 body exclusive of the part 2 where the patterns are formed. The depth of the recess 3 provided on the part except the pattern forming part 2 of the glass master disk 1 body is gradually diminished according to the number of polishing times until finally the recess 3 disappears if the glass master disk 1 is subjected to repeated polishing with the reuse thereof. The visual checking that the reuse of the glass master disk 1 is still possible as far as the recess 3 provided to the glass master disk is visible is possible in this way.