
38 Fundamentals of Computer Programming and IT
In CD-RW disk, the recording layer has poly-
crystalline structur
e initially. While writing to the
disk, the laser heats up the selected areas to a very
high temperature (above the melting point), which
melts the crystals into non-crystalline amorphous
phase. These areas have lower reflectance than
the remaining crystalline areas. This difference in
reflectance helps in reading the recorded data as in
the case of CD-R disk.
To erase data on a CD-RW disk, a process
called annealing is used. During this process, area
on the layer that has been changed to the amor-
phous phase (during writing) is converted ...