Abstract

The Dual layer disc (DLD) is the simplest realization of a multi-layer disc that opens up the possibility of three-dimensional recording in the optical disc world. DLD technologies first appeared in patents from several companies in the last decade or so. (For example, refer to [1] from Philips). DLD technologies are very important in optical disc systems because there are no other possibilities by which we can acquire a factor of 2 increase in recording capacity while using a conventional optical pickup. Although this advantage has been known for many years, the DLD was thought to be too difficult to make for commercialization. However, the DLD has been finally adopted as the Digital Video Disc (DVD). Since then, a great deal of effort has been expended to make the DLD truly feasible for mass production. DLD technologies have been updated and they are now about to be transferred from the laboratory to factory. In this paper, I will describe the principles of these DLD technologies.

© 1996 Optical Society of America