532nm対応高感度フォトポリマー材料によるホログラム記録

抄録

The photographic properties of photopolymerizable composites initiated by the combination of a radical generator and spectral sensitizer were investigated under exposure to light of wavelength 532 nm. The photopolymerizable layer consists of four components: matrix polymer; multifunctional monomer; radical generator; and a dye sensitizer such as cyanine, merocyanine, or indolenine dyes. The dye exhibits an absorption maximum at around 532 nm. Because radical generators such as 2- (p-methoxyphenyl) -4, 6-bis (trichloromethyl) -s-triazine (TCT) and 3, 3'-bis (methoxycarbonyl) -4, 4'-bis (t-butylperoxycarbonyl) benzophenone (BT2) exhibit sensitivity only up to the ultraviolet region, they cannot be directly used as photoinitiators for green-light-sensitive imaging materials. However, the addition of a sensitizing dye extends the spectral sensitivity range of these radical generators toward the longer wavelengths. Upon initiation by BT2 sensitized with cyanine dye, the sensitivity of the photopolymer to light of wavelength 532 nm was 30 μJ⁄cm². The sensitization of the radical generator by the dye involves electron transfer from the excited dye to the radical generator. The holographic properties of photopolymers initiated with the merocyanine⁄BT2 system were evaluated in terms of diffraction efficiency. Real-time diffraction efficiency measurements of transmission holograms were carried out using an optical system equipped with a Nd: YAG laser (532 nm), A hologram with high diffraction efficiency (∼80%) can be formed at 300 mJ⁄cm² exposure.