Write-once information recording medium and coloring matter therefor

摘要

A write-once information recording medium (28) comprises a transparent resin substrate (20) having a concentrically or spirally shaped groove (21) and a land (30) formed thereon, and a recording firm (24) formed on the groove (21) and the land (30) of the transparent resin substrate (20), a recording mark being formed on the medium by emission of a short wavelength laser light, the recording medium having an L to H feature in which a light reflectivity of the recording mark portion formed by the emission of the short wavelength laser light is higher than a light reflectivity obtained before the emission of the short wavelength laser light.