Making memory structure for laser recording system

DETAILED DESCRIPTION In accordance with the present invention, a thermoplastic memory is formed by depositing two layers of material upon a metallic substrate such as aluminum.
The first or preliminary layer is a nonconformal layer and a dyed conformal thermoplastic layer is applied over the preliminary layer.
This outer thermoplastic layer performs as in the preexisting systems, but since the preliminary layer is nonconformal, it provides a smooth, intermediary surface upon which the thermoplastic layer is placed.
Thus without the costly polishing of the substrate the surface of the thermoplastic layer is smooth notwithstanding the substrate's roughness.
Since the thermoplastic surface is smooth, many of the problems caused by surface imperfections are eliminated.
In particular, the depth of focus during the writing process is nearly constant, and the signal-to-noise ratio is improved by the reduction of the background light scattering.
The preliminary layer also provides thermal insulation of the substrate which results in improved writing since very little writing energy is dissipated in the substrate.
An additional improvement can be provided by using an efflorescent material as the outer thermoplastic layer.
This material will form bubbles in the interior surface of the grooves and will therefore produce a much higher signal-to-noise ratio when detected than would be provided by the smooth interior surfaces of the grooves formed in conventionally used thermoplastics.