Optical disc drive beam on a smaller spot size and to read smaller pits. DVD lens supports a different focus for CD or DVD media with same laser. With the newer Blu-ray disc drives, the laser only has to penetrate 0.1 mm of material. Thus the optical assembly would normally have to have an even greater focus range. In practice, the Blu-ray optical system is separate from the DVD/CD system. During the times of CD writer drives, they are often marked with three different speed ratings. In these cases, the first speed is for write-once (R) operations, the second speed for re-write (RW)
Ultra Density Optical 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 30 GB of data. The second generation UDO2 media was introduced in April 2007 and has a capacity of up to 80 GB. Utilising a design based on a Magneto-optical disc, but using Phase Change technology combined with a blue violet laser, a UDO/UDO2 disc can store substantially more data than a magneto-optical disc or MO, because of