Photochromic polymers for erasable focal plane masks and re-writable volume phase holographic gratings

摘要

Thermally irreversible photochromic materials, mainly belonging to the diarylethene class, are potentially useful as optoelectronic devices. Poly-l,2-bis-(2-methyl thiophen-3-yl)perfluorocyclopentene has been studied in order to verify its possible application in astronomy for the production of re-writable focal plane masks and volume phase holographic gratings. Films of photochromic materials embedded in an amorphous polymer matrix are obtained by casting from chloroform solution. The films show a good transparency in the visible region when the photochromic molecule is in the open-ring form, while they totally absorb visible wavelength radiations when the photochrome is in the other isomeric form. The variation in refractive index between the two photochromic isomers, evaluated by UV-vis-NIR absorption spectra, is large enough to make this photochromic apt for the production of volume phase holographic gratings.