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)
Compressed audio optical disc case and disc drive exposes the disc to dust, and also makes the disc liable to be damaged permanently. Also note that some CD and DVD discs also have defective aluminum layers that can flake, and damage the disc naturally. Repeated insertion and removal of optical discs can occur when somebody has to deal with multi-gigabyte collections which can span across as many as 10 CD-Rs (or 5 DVD-Rs) or even more when lots more gigabytes were to be used. Sometimes when somebody is looking for a specific MP3 or similar; it can result in insertion and removal if more