Yamaha 6416 CD-RW - Part 5

Phase-Change Technology Part II

Over at the top, we have the power levels of the laser during recording. There are 3 levels, Pwrite, Perase and Pbias. The CD-RW drive has to be pulsed to form well-defined amorphous regions. This is different from traditional CD-R drives where the laser is left at constant power and the only thing change is the time required to form the "pit" on the dye.

Hence this write strategy writes new data to the disc and at the same time, it simultaneously overwrites old data.

Rewriting Data
So, how does a CD-RW rewrites it's data? The CD-RW drive uses pulsed beam to write amorphous "pits" as well as non-pulsed beam to write crystalline "lands" between the "pits". Hence this write strategy writes new data to the disc and at the same time, it simultaneously overwrites old data. This procedure can be repeated for several thousand times. Totally cool!

CD-R DYES
I will just give a brief explanation on the various types of CD-R dyes used. There are currently two popular dyes used in the market. The CYANINE dye as well as the PHTHALOCYANINE (pronounced thal-o-sy-a-nene) dye.

CYANINE dye can be identified by their emerald green or cobalt blue color. This is the most popular dye you see in the market. The dye itself is blue, but may appear in different colors based on the material used for the reflective layer. For example, a gold reflective layer will produce the green color while a silver reflective layer will produce the blue color.

PHTHALOCYANINE dye can be identified by thier almost clear yellow-green color. You see them in CD-R which appear gold or greenish gold. Lifetime of the PHTHALOCYANINE are longer than CYANINE dye and estimated to be about 100 years.

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