| To record on a CD-R, the CD-R drive
employs a laser beam with the same wavelength as that used when reading a CD, yet at a
much higher strength. To guide the laser, the CD-R disc features a spiral groove molded
into its surface, unlike a pressed CD. When recording, the laser focuses on the disc,
generating heat to above 300º on only the affected region. This causes the organic dye
(found in the recording layer) and the substrate of that small area (0.6 microns wide) to
be physically altered. Not surprisingly, the optical characteristics (refractive index) of
that area are also altered and this is the difference between "burned" and
"not-burned" areas which is recognized by the other CD drives. Summary based on information from the Maxwell site: http://www.maxell.com/cdr/techinfo/cdrbasic.htm and Upgrading and Repairing PCs. |