1.3.4 Optical Storage & Properties

Each 1 or 0 (value of a bit) is represented as a microscopic hole (called a pit) or a flat surface (called a land) on the surface of the disk.

A laser is shone on the disk surface. If the laser hits a land, it will be reflected into a sensor. If the laser hits a pit, then it will be reflected elsewhere. These can be used to represent our 1 and 0.

Optical media is: Waterproof. Shockproof. This makes it ideal for portability (transporting).

Optical media is very cheap per-gigabyte (GB).

Each disk has a low capacity. Disks are small and fairly cheap. So it can be easy to gain a high capacity of storage by buying multiple disks.

Because the parts in the optical media drive have to move to find the right bit of data on the disk, access times can be quite slow. Writing to a disk can also be a very slow process.