a photochromic fulgide, coimnonly known as aberchrome 540, is amber in its ring-opened e (see document) dimethyl -3- furylethylidene) (isopropylidene) succinic anhydride] and z (see document) furylethylidene) (isopropylidene) succinic anhydride]. the e form is dispersed in various polymer matrices to form thin solid films on quartz plates by a solution-cast technique.