US Patent 7758944 Optical medium and method for making the same

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.