Is there difference between azo, phthalocyanine, and cyanine dyes?
The first to be used was the cyanine dye, and its characteristics are referred to in the Orange Book Part II standard. More recently Phthalocyanine dye is being used, it would appear to be less sensitive to light after recording, so it may last longer. Azo dye has been used in other optical recording media and is now being used for CD-R media. Each manufacturer is making tradeoffs to get the best price/performance, however as CD-R media must conform to an exacting standard then the practical differences are small.
