HIGH DATA DENSITY OPTICAL MEDIA DISCS

摘要

A high data density pre-recorded optical media disc having a data density of at least 7.5 Gigabytes per disc layer or 0.17 Gigabytes per square cm (Gb/cm<2>) per layer and a degree or replication such that the average pit depth equals 1/4 to 1/8 times (the wavelength of the laser divided by the refractive index of the disc); or a rewritable optical media disc having a data density of at least 0.05 Gb/cm<2>, wherein at least 75 percent replication is achieved as measured by a combination of groove height and the left and right sidewall angles, and wherein the pre-recorded or rewritable disc has a retardation of less than 25 nm per 0.6 mm substrate thickness, and a water absorbance of less than 0.5 percent as measured according to ASTM D570.