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)
Nintendo optical discs Optical Disc" (RVL-006) is the physical game medium for the Wii, created by Panasonic. Nintendo extended their proprietary technology to use a full size 12 cm, 4.7/8.54 GB DVD-based disc, enabling it to have the benefits of the GameCube Game Disc, while having the standard capacity of a double-layer DVD-ROM. Although the Wii can use double-layer discs, all titles were single-layer prior to the release of "Super Smash Bros. Brawl". With the release of "Super Smash Bros. Brawl", Nintendo admitted that some Wii systems may have trouble reading dual-layer discs due to a dirty laser lens. Nintendo repaired systems with