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<title>Photochromic materials for holographic data storage</title>

1999; SPIE; Volume: 3897; Linguagem: Inglês

10.1117/12.369293

1996-756X

Roger A. Lessard, Christophe Lafond, Fatima Ghailane, Michel Bolte, Amir Tork, Ivan Petkov,

Light effects on plants

Photochromism and real-time holographic recording were characterized for two principal classes of photochromic compounds: spiropyrans and fulgides. For spiropyran molecules, important thickness and writing intensity effects were observed. Concerning fulgide, in PMMA matrix, the closed form presents a maximum of absorption centered at 525 nm upon irradiation at 365 nm. We have determined the photoreaction rate constants k UV and k vis respectively for the coloring and bleaching process: k UV equals 1.2 X 10 -3 s -1 and k VIS equals 11.1 X 10 -3 s -1 . Photochemical fatigue resistance in different polymer matrices was investigated. We found a loss of 9, 11, 13 and 35 percent respectively in PS, CA, PMMA and PVK. Concerning holographic recording, we obtained diffraction efficiency (eta) equals 0.65 percent in PMMA films 30 micrometers thick.