Two dyes for holographic recording material: panchromatic ion pair from Rose Bengal and Methylene Blue

An ion pair (RBMB) isolated from Rose Bengal and Methylene Blue has been us ed as the photoinitiator in formulations of photopolymers tested as hologra phic recording materials in the form of dry films. Under irradiation with l ight of wavelength 633 or 514 nm, diffraction efficiencies of 65 and 35%, a nd sensitivities of 30 and 100 mJ cm(-2) have been respectively reached, wi th a spatial resolution of ca. 1000 lines mm(-1). These holographic respons es are better than those reached under comparative conditions using a 1:1 p hysical mixture of the individual dyes. The influence of the light intensit y on the photoinitiation of the polymerization process yielding the hologra m has also been studied.