Ultra Density Optical

Ultra Density Optical (UDO) is an optical disc format designed for high-density storage of high-definition video and data.An Ultra Density Optical disc or UDO is a 133.35 mm (5.25") ISO cartridge optical disc which can store up to 60 GB of data.[clarify] Utilising a design based on a Magneto-optical disc, but using Phase Change technology combined with a blue violet laser, a UDO disc can store substantially more data than a magneto-optical disc or MO, because of the shorter wavelength (405 nm) of the blue-violet laser employed. MOs use a 650 nm-wavelength red laser. Because its beam width is shorter when burning to a disc than a red-laser for MO, a blue-violet laser allows more information to be stored digitally in the same amount of space.

Current generations of UDO store up to 60 GB, and a 120 GB version of UDO is in development and is expected to arrive in 2007 and after, though up to 500 GB has been speculated as a possibility for UDO.According to Plasmon, desktop UDO drives are priced at around US $3200. A 30GB UDO Write Once is US $60.Originally an optical disc storage medium developed as a replacement for the Magneto-optical digital storage medium, Ultra Density Optical was developed beginning June 2000 and first announced by Sony on November 1st 2000.[3] It was later adopted with heavy investment by Plasmon, a UK technology company with extensive experience with computer archival backup systems and solutions.Currently UDO is being championed by its development partners Plasmon (Company), Hewlett Packard, Asahi Pentax (responsible for the opto-mechanical assembly design), Mitsubishi Chemical, parent company of the Verbatim media storage brand, and various computer and IT solutions companies. Mitsubishi Chemical is the second major development partner of UDO media.UDO uses a Phase Change recording process that permanently alters the molecular structure of the disc surface.There are three versions of UDO 30: a True WORM (Write Once Read Many), an R/W (Re-Writable), and Compliant WORM (shreddable WORM).The UDO Rewritable format uses a specially formulated Phase Change recording surface that allows recorded data to be deleted and modified. In practice, UDO Rewritable media operates like a standard magnetic disc. Files can be written, erased and rewritten, dynamically reallocating disc capacity. Rewritable media is typically used in archive applications where the stability and longevity of optical media is important, but the archive records change on a relatively frequent or discretionary basis. Rewritable media is typically used in archive environments where data needs to be deleted or media capacity re-used.UDO systems use a blue-violet laser operating at a wavelength of 405 nm, similar to the one used in Blu-ray, to read and write data. Conventional MOs use red lasers at 660 nm.[6]

The blue-violet laser's shorter wavelength makes it possible to store more information on a 13 cm sized UDO disc. The minimum "spot size" on which a laser can be focused is limited by diffraction, and depends on the wavelength of the light and the numerical aperture of the lens used to focus it. By decreasing the wavelength, using a higher numerical aperture (0.85, compared with 0.575 for MO), the laser beam can be focused much more tightly. This produces a smaller spot on the disc than in existing MOs, and allows more information to be physically stored in the same area.The opto-mechanism design of current Plasmon UDO drives was jointly developed with Asahi Pentax.