Laser Scribing Magnetic Defects on Disks
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
Laser scribing is a technique in which a laser is used to etch precise patterns in the magnetic coating of a disk. This results in a disk with a predictable, large number of magnetic defects. This makes the disk a useful tool for correlating two or more disk testers, for calibrating testers, and for periodically verifying, during production, that the test heads have not degraded and that tester sensitivity has not shifted. Flaws in the magnetic coating and/or substrate of a disk generally manifest themselves as one of four types of magnetic defects: missing bits, extra bits, envelopes and modulation defects. By using a laser to scribe precise patterns at specific locations on the disk, each of these defects have been created with a reasonable degree of predictability.