PHOTOCHROMIC PERFORMANCE OF FULGIDE ON DISK AS DATA-STORAGE MEDIA

Photochromic fulgides, e.g. 4-oxazolyl type [1] approximately [3] and 3-furyl type fulgide [4] and [5] were synthesized. And the optical fulgide disks were prepared by spin-coating method, and recorded with argon ion laser emitting at 514.5 nm. Fulgide[3] disk (fulgide content ; 6.4 wt%) exhibited high C/N ratio (47 dB) from the read-out signal because of the high absorption coefficient of colored fulgide (26000 M-1cm-1). On the other hand, fulgide [5] disk did not show enough C/N ratio for practical use, because of the low absorption coefficient (6200 M-1cm-1). Recording power was dependant upon the quantum yield, and fulgide [5] disk which featured high bleaching rate needed lowest recording power (5 mW). Though fulgide [3] exhibited low quantum yield for bleaching (1. 8 X 10(-4)), it was possible to record on the disk. And the disk showed high read-out stability and record-erase cycle fatigue resistance.