Abstract: In one embodiment, the invention is directed to a manufacturing process for optical data storage disks that makes use of a check disk very early in the production cycle. The check disk can be replicated directly from the master without destroying the master. The check disk may then be tested in order to validate the pattern created on the master. In some cases, the check disk may be delivered to customers, allowing the customers to verify the check disk. Once the check disk has been verified, the master can be used to create one or more stampers, which can be used in a mass production process for creating optical data storage disks. However, if the check disk is defective or otherwise not acceptable, the production cycle can be halted prior to creating any stampers. In this manner, the invention can be used to avoid creation of defective stampers or other defective mass production tools.

Abstract: The invention is directed toward techniques for stamping optical data storage disks. A master is first created to include several distinct information regions etched upon a master surface. The master is then used to create one or more stampers. The stampers include a number of distinct stamper regions in locations corresponding to locations of the distinct information regions on the master. The stamper is then used to create a number of first replica disks that include distinct replicated regions. The distinct replicated regions are removed from the first replica disks to define second disks.

Abstract: A dual layer optical disc having images encoded therein. The dual layer optical disc includes a first data layer and a second data layer coupled to the first data layer. An optically viewable image is encoded within the first data layer or the second data layer. The viewable image may be a light contrast, medium contrast, or high contrast image. The first data layer and the second data layer may have a balanced reflectivity rating. In another embodiment, the first data layer and the second data layer have an unbalance reflectivity rating, for varying the visibility of images encoded therein. The dual layer optical disc may further include a second side, having a third data layer and a fourth data layer having an optically viewable image encoded within the third data layer or the fourth data layer. The optically viewable image may be a holographic image.

Abstract: Techniques for marking of optical data discs with a unique characteristic marking for purposes of identification and verification of authenticity. The marking, referred to as a `watermark`, can be a name, logo, design, picture or other pattern which is applied within the structure of the data disc. The watermark is applied to the master disc, and will therefore be reproduced in all production replica discs through the use of standard stamper and replica processes. In a preferred embodiment the watermark is a modification to the periodic diffraction grating effect created by the encoded data by alteration of the thickness or depth of the data feature with respect to the reference plane of the data structure in areas defining the watermark. The watermark can then be seen in the final disc as a discontinuity or difference in the rainbow-like diffraction pattern on the surface.