4 июля, 2015 
Malyar Due to the absorption band of the colored form of spiroindolinoben- zothiopyrans in the near IR region, they have been used in the optical erasable recording disks.89,100,101 The principle of optical erasable recording system using photochromic spirobenzothiopyran is explained as follows.
First, the recording layer which contains photochromic spirobenzothiopyran in liquid-crystal polymer or polymer such as vinyl chloride — vinylidene chloride copolymer, is made colored by UV irradiation. In the recording (writing) process, a colorless recording dot in the recording layer is formed by semiconductor laser beams (789 nm, 15-20 mW).100 This process is essentially thermal decoloration of the photomerocyanine form by laser beam.
In the reproducing (reading) process, the presence of the colorless form is detected by difference in reflectivity using the same laser beam at weak power (1 mW), and the signal is picked up by photodiode. In reversible process, the nonrecording area again was obtained by UV irradiation. Practically, in such optical disks using spirothiopyran, an S/N of 54 dB was detected.89-100
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