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)
Picture disc picture disc is "To Elvis: Love Still Burning", a collection of 11 Elvis Presley tribute songs by various artists, issued in May 1978. Both sides of the album (Fotoplay FSP-1001) picture Presley. On some picture discs, the images used were meant to create an optical illusion while the record was rotating on the turntable (as in the B side of Curved Air's "Airconditioning"), while others used the visual effect to add to the music — for example, the 1979 picture disc of Fischer-Z's "The Worker" featured a train which endlessly commuted around the turntable, reinforcing the song's message. Later picture