Optical discs with cover sheets and dynamic pressure stabilization of the enclosed air

An optical disc having a substrate in which data can be written on or read from, such optical disc being adapted to be inserted and clamped onto a spindle in a disc drive and having a transparent cover sheet disposed over the substrate surface. The optical disc has a perimeter ring on the edge thereof and a spacer formed adjacent to a central opening in the disc. The perimeter ring is formed with a plurality of air passages leading from the space between the transparent cover sheet and the substrate surface to the outside atmosphere and the spacer is formed with a plurality of air passages leading from the outside atmosphere to the space between the transparent cover sheet and the substrate surface. Filters are provided in the air passages in the spacer and the perimeter ring to prevent contaminants from the atmosphere from entering into the space between the transparent cover sheet and the substrate surface.