Patent ID: 7378220

Claim:
An optical information recording medium used in a method of recording information by irradiating the medium with a laser having a wavelength no greater than 450 nm, wherein a recording layer of the optical information recording medium contains a phthalocyanine compound represented by Formula (I): wherein R α1 to R α8 and R β1 to R β8 each independently represents one selected from the group consisting of a hydrogen atom, an alkylsulfonyl group having 1 to 20 carbon atoms, an arylsulfonyl group having 6 to 14 carbon atoms, and an aralkylsulfonyl group having 7 to 15 carbon atoms; and M represents a metal selected from the group consisting of zinc, magnesium, copper, nickel, and palladium and wherein at least four of the R α1 -R α8 substituents in the Formula (I) are not simultaneously hydrogen atoms; wherein the refractive index of the recording layer is more than 1.5 and less than 1.9 at the wavelength of laser light used in recording; and wherein a pre-groove having a track pitch of 0.2 to 0.5 μm is formed on the surface of the substrate disposed with the recording layer of the medium.