Experiments showinga rapid and reversible change ofcolor s eem likemagic
and are always fascinating. The process involved, photochromism, has a
few real and many potential applications. Photochromic glasses
thatdarken int he s unlight (protecting eyes from excessive light
intensity) and bleach ind im lighta re today a part ofe v eryday life.
Organic photochromic compounds in plastic ophthalmic lenses, more
comfortable to wear, are now competing with silversalts in glasses,
despite the longer lifetime oft he inorganic system. This successful
commercial application has given a new impetus to research in the
general field of photo chromism, which had its most recent revival in
the early eighties. The storyo forganic photochromism with its ups
anddowns, from the breakthroughs oft he pioneering periodi n the
fifties, through the hardtimes dueto the drawbacks of photodegradation,
tot he recent successes is in many ways a saga. The upsurges in this
domain were marked by an increasing flow of articles in scientific
journals andt he publication of several books (in 1971, 1990, and 1992)
that have collectedt he important accumulatedknowledge. Over this
period, a considerable number ofpatents have been issued. International
meetings have accompanied this activity, the most recent being held in
1993 (ISOP 93 atLes Embiez Island, France) and in 1996 (ISOP 96
inClearwater, Florida). Remark ably, these meetings had good
representation from both academia and industry. The next ISOP is planned
for 1999 in Fukuoka, Japan.