Ultra density optical (UDO) is an optical storage technology that increases capacities by using an extremely focused blue laser to write and read data. Hewlett-Packard (HP), Sony, and Plasmon collaborated on the UDO standard, which is intended as a replacement for consumer market DVD as well as mass storage. UDO is, however, not backwards compatible with existing optical media and drives. UDO devices use phase change recording for both rewritable and write once read many (WORM) formats.
First generation UDO media offers 30 gigabyte (GB) capacities, with 120GB expected by 2007 (DVD capacity, at 4.7GB for a single-sided disc, is comparatively low). The cost of UDO storage, at about $2 per gigabyte, is more expensive than tape, but significantly less costly than other optical storage formats.