Abstract: Improved structures of optical medium are disclosed. According to one embodiment, multiple reflective layers are used. These reflective layers are in different materials. At least one of the reflective layers allowing a significant amount of a laser beam to transmit is used to protect another reflective layer with superior reflectivity from moisture on one side. An additional reflective layer may also be used to protect the high reflective layer from moisture on the other side.

Abstract: Techniques for bonding two disks with a minimized eccentricity (ECC) are disclosed. A positioning header includes an ECC controlling structure that further includes a positioning header. In one embodiment, the position header includes three members that form a round stand with a diameter smaller than the inner diameter of the disks. The round stand expands to the inner diameter of the disks to close the gap as a result of the difference between the two diameters when the three members are caused to expand. In one embodiment, the movement of the three members is controlled by magnetic means. Depending on the positions of the ECC controlling structure, the three members are expanded from or restored to their default positions.

Abstract: Techniques for bonding substrates are disclosed. According to one aspect of the techniques, an index bonding is provided to ensure that non-flatness of substrates is compensated when two substrates are bonded together so as to minimize possible dynamic imbalance of a disc. According to another aspect of the techniques, a dynamic alternating electric field bonding is provided to eliminate bubbles from a type of glue used to bond two substrates, wherein a power source is used to generate a dynamic alternating electromagnetic field in accordance with the substrates and/or the characteristics of the glue.

Abstract: Techniques for producing optical medium that can be read at substantially high speeds with greater stability and accuracy are disclosed. According to one aspect of the techniques, a bonding station is employed with what is referred to as a bubble-free bonding technique that may or may not be incorporated with an index bonding technique. The index bonding is provided to ensure that non-flatness of substrates is compensated when two substrates are bonded together so as to minimize possible dynamic imbalance of a disc. The bubble-free bonding technique is provided to generate an alternating electromagnetic field that eliminates bubbles from a type of glue used to bond two substrates, wherein a high voltage source is used to generate the alternating electromagnetic field of a predefine magnitude.