Two-sided, light-readable information recording disc stacks and methods of making same

Claim 1

An information recording medium comprising: a first substantially transparent plastic disc having a first substantially planar surface and a second surface opposite to said first surface, said second surface having information recorded on it by means of local changes in the distance of said second surface from said first surface; a first light reflecting coating on said second surface for reflecting light passed through said first disc back through said first disc, said first coating conforming to said local changes of said second surface so that said light is reflected back through said first disc in accordance with the information recorded by means of said local changes; a second substantially transparent plastic disc of approximately the same thickness as said first disc, said second disc having opposite, substantially planar, third and fourth surfaces, said second disc being stacked on and secured to said first disc so that said third surface faces toward said second surface; and indicia on said second disc that are visible by viewing said fourth surface for visibly providing a user of said recording medium with identifying information related to the recording medium, said indicia being formed by means of variations in the thickness of the plastic of said second disc produced via local changes in the distance of said third surface from said fourth surface; wherein said indicia comprise local modifications of said third surface.