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)
Optical disc packaging has largely been replaced with the DVD keep case and CD jewel case due to its flimsy design. Warner Brothers and New Line Cinema were the only major film studios to release DVDs in this format. Soft cases, also known as Earth cases or Green cases, are soft-shell cases made from recycled optical discs. They are considerably more pliable than other style cases given that they are made from various mixes of plastics. They are sold by various companies as replacements for disc owners who are environmentally friendly and can be differentiated from other cases by their opaque appearance. The