Abstract: A BCA mark is applied prior to molding of optical recording media. A stamper including a BCA code is formed. The stamper including the BCA code is used in the molding of optical recording discs. This technique can be used in manufacturing of read-only type discs, recordable discs, rewritable discs, hybrid discs, discs readable from both disc sides, discs having multiple information layers, high-density discs, etc.

Abstract: A BCA mark is applied prior to molding of optical recording media. A stamper including a BCA code is formed. The stamper including the BCA code is used in the molding of optical recording discs. This technique can be used in manufacturing of read-only type discs, recordable discs, rewritable discs, hybrid discs, discs readable from both disc sides, discs having multiple information layers, high-density discs, etc.

Abstract: A BCA mark is applied prior to molding of optical recording media. A stamper including a BCA code is formed. The stamper including the BCA code is used in the molding of optical recording discs. This technique can be used in manufacturing of read-only type discs, recordable discs, rewritable discs, hybrid discs, discs readable from both disc sides, discs having multiple information layers, high-density discs, etc.

Abstract: An improved optical disc is provided that comprises a substantially transparent substrate, one surface of which carries optical data structures comprising pits and lands radially outward of a clamp area of the disc. In the clamp area a protrusion structure is provided above the first surface to create a clamp thickness greater than the thickness of the rest of the disc. In accordance with the principles of the present invention, only a portion of the clamp area is covered by the protrusions, which emulate a disc having a clamp area of greater thickness. In order to reduce warping caused by shrinkage of material added to the clamp area, the amount of material used to form the protrusions is less than 5% of the amount of material used to form the rest of the clamp area.

Abstract: An improved optical disc is provided that comprises a substantially transparent substrate, one surface of which carries optical data structures comprising pits and lands radially outward of a clamp area of the disc. In the clamp area a protrusion structure is provided above the first surface to create a clamp thickness greater than the thickness of the rest of the disc. In accordance with the principles of the present invention, only a portion of the clamp area is covered by the protrusions, which emulate a disc having a clamp area of greater thickness. In order to reduce warping caused by shrinkage of material added to the clamp area, the amount of material used to form the protrusions is less than 5% of the amount of material used to form the rest of the clamp area.