Multiple Optical Memory using Photochromic Spiropyran Aggregates

Multiple recording technology is particularly important for the high density optical memory. Through investigating the aggregate—forming ability of the new photochromic spiropyrans, we have developed five novel spiropyrans, the aggregates of which have sharp absorption bands at different wavelengths. We have fabricated a recording medium stacked with the five kinds of aggregate layers and confirmed ten multiple optical recording characteristics by combining the five multiple frequency recording with the recording by two mutually perpendicular linear—polarized lights.