Video recording disc - with an ablative layer of a chloro-phthalocyanine cpd. of lead, vanadium, tin or aluminium on a reflective substrate

摘要

Ablative optical recording medium comprises a light reflecting substrate coated with a layer of light absorbing dye offormula (I) in which X is hydrogen or chlorine and M is lead, aluminium, vanadyl or tin (+4). The thickness of the dye layer is pref. chosen to minimise the reflectivity to a light source emitting light of about 750-850 nm wavelength. The (I) form smooth, optical quality light absorption layers which ablate on the action of recording beams from low power aluminium gallium arsenide layers operating at 750-850 nm. The (I) absorb strongly at this wavelength and give recorded information having a very high signal to noise ratio. The prods. are esp. useful as video discs.