Optical disc and method of producing the same

Abstract

An optical disc includes a first substrate and a second substrate. The first substrate has a thickness of 0.6 mm±30 μm, with a first recording layer formed thereon. The first recording layer has a string of first data pits concentrically or spirally formed in compliance with the DVD-ROM specifications. The second substrate has a thickness of 0.5 mm±30 μm, with a first surface and a second surface on both sides. A second recording layer is formed on the first surface, as having a string of second data pits concentrically or spirally formed in compliance with the DVD-ROM specifications. A third recording layer is formed on the second surface, as having a string of third data pits concentrically or spirally formed in compliance with the BD-ROM specifications. A first reflective film is formed on the first recording layer. A second semi-transparent reflective film is formed on the second recording layer. The first and second substrates are bonded to each other so that the first and second reflective films face each other. A third semi-transparent reflective film is formed on the third recording layer, as having a thickness in the range from 5 nm to 20 nm. A transparent layer having a thickness of 100 μm±3 μm, with a third surface and a fourth surface on both sides, is formed on the third reflective film at the third surface. The fourth surface allows a laser beam to pass therethrough in reproduction from the first, the second, or the third data pits.

Dependencies are inferred from the claim text.