Patent ID: 7567499

Claim:
An optical disc comprising: a first substrate having a first surface, the first surface having a first recording layer formed thereon, the first recording layer being capable of storing first data in compliance with first specifications; a first reflective film formed on the first recording layer; a second substrate having a second surface and a third surface on both sides, the second surface having a second recording layer formed thereon, the second recording layer being capable of storing second data in compliance with the first specifications, the third surface having a third recording layer formed thereon, the third recording layer being capable of storing third data in compliance with second specifications different from the first specifications; a second semi-transparent reflective film formed on the second recording layer, the second semi-transparent reflective film having a thickness in the range from 5 nm to 15 nm; a third semi-transparent reflective film formed on the third recording layer; an adhesive layer provided between the first and second reflective films; and a transparent cover layer, having a thickness of 100 μm±3 μm, with a fourth surface and a fifth surface on both sides, the transparent layer being formed on the third semi-transparent reflective film at the fourth surface, the fifth surface allowing a laser beam to pass therethrough in reproduction of the first, the second or the third data from the first, the second, or the third recording layer, respectively.