Effect of partial crystallization on formation of amorphous marks

A difference in initial state of a phase-change disk causes a difference in the final-state reflectivity of an amorphous mark under identical mark writing conditions. Static testing of a first-surface disk demonstrates that a 8% difference in reflectivity exists between the amorphous marks formed in a finally-crystallized, high reflectivity state and partially crystallized, low reflectivity state. This difference in final state reflectivity is a source of noise for rewritable phase-change optical disks.