Recording material for storage of digital information and a recording method for storage of digital information

Recording method operating with information-wise modulated laser beams comprising the steps of

• (1) information-wise pulsed irradiation with a first laser beam of a recording material comprising on the same side of a laser radiation-reflective support, including a support with laser radiation reflecting layer, two superimposed adjacent recording layers which can undergo on exposure instantly produced optical density changes responsive to irradiation with laser beams of different wavelength, the compositions of said layers being such that they have different radiation-sensitive characteristics permitting information-wise recording to take place in one layer without changing the optical density of the other layer to such a degree that laser beam read out of optical density information in one layer becomes impossible upon using laser beams of different wavelength for each recording layer, wherein said first beam is focused onto a thermosensitive recording layer of said recording material, while having a relative movement between said thermosensitive recording layer and said beam, the exposure with said first beam being of sufficient dose to produce in said thermosensitive recording layer a pattern of a physical change associated with a change in optical density, and
• (2) information-wise pulsed laser irradiation of said recording material with a second laser beam which beam is focused onto a photosensitive recording layer of said recording material while having a relative movement between said photosensitive layer and said second laser beam whose laser radiation contains electromagnetic radiation of the visible and/or ultra-violet wavelength range in the spectral sensitivity range of the photosensitive layer, the exposure of the photosensitive recording layer being information-wise such that a detectable colour or colour change is formed therein without affecting the thermosensitive layer, the recording of information with the first laser beam in the thermosensitive recording layer being such that therein the optical density is modified without modifying the optical density of the photosensitive layer in such a degree that the selective laser beam read out of recorded information in each of the recording layers by using laser radiation of different wavelength becomes impossible.