US Patent 7684309 Multi-purpose high-density optical disc

An optical recording medium includes a first half-disc and a second half-disc. The first half-disc includes a substrate and an information layer (including a reflective layer) formed on a first side of the substrate. The second half-disc is bonded by an adhesive to a second side of the substrate of the first half-disc. In addition, a cover layer is formed over the first reflective layer. The cover layer has a thickness of approximately 0.1 mm. The substrate of the first half-disc has a thickness in a range of 0.3 mm to 1.0 mm. The first and second half-discs together have a combined thickness in a range of 0.8 mm to 1.3 mm.