Abstract

Recently the blue-violet laser diode has enabled the recording and readout of high-density optical discs with recording capacity of about 25 gigabytes (GB) in the size of Compact Disc (CD). On a rewritable disc, the groove structure is preformatted. It can be formed even with a conventional 266 nm far-field mastering process. As for a read only memory (ROM) disc, small-pit patterns must be preformatted. Making those patterns requires a smaller spot size for exposure than can be obtained by the conventional far-field process.

© 2003 Optical Society of America