AFM analysis of CD-R photoageing

One of the main parameters controlling durability of optical discs such as CD-R is the stability of the dye layer. Ambient light exposure contributes to degradation of the light-sensitive dye used in recordable media. Our study focuses how light irradiation influences the dye layer on a polycarbonate (PC) substrate before and after CD-R engraving. The dye layer surface was characterized by atomic force microscopy (AFM) to measure dye degradation, which, in turn, can be used to assess CD-R readability. For a blank CD-R, pre-groove height is a major degradation indicator. For a recorded CD-R, however, pit and land size and depth can be used to show degradation. For long irradiation times, coded areas completely disappear, leading to the loss of stored information.