Digital Video's Next Generation?

THE FIRST BATCH OF digital videodisks to hit the market pack full-length movies onto a single disk. But the players can't record, which means they probably won't replace VCRs in most living rooms. To address this issue, manufacturers are already hard at work on recordable DVD players, due in 1999. But at least one top maker--Sony Corp.--says current technology can't be extended to store high-definition images, which require more digital storage room than current-generation TV images.

So Sony has struck out on its own. By 2000, it hopes to commercialize an optical disk system that can record 12 gigabytes of data on one side of a standard 12-centimeter disk. That's 4.6 times as much as DVD-RAM, a recordable version of DVD, hitting the market as a computer storage device. Sony's prototype can record 5 hours of conventional TV programming or 1.2 hours of high-definition TV.

To inscribe the billions of bits that represent pictures and sounds on disks, the prototype uses a highly focused blue-green laser. Sony also changed the disk structure from that of DVDs. Eventually, Sony plans to move to pure blue lasers, which can pack data about 50% more densely. The biggest hurdle: making the lasers more robust. Sony's blue-green laser lasts only

10 hours vs. 10,000 required for a commercial