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CD Recording FAQ
2. The CD Recorder
2.3. How CD-R (Recordable) works
The basic idea behind cd-r is a laser beam following a spiral trajectory on the surface of a blank cd, travelling from inwards to outwards. During this trajectory, the laser is powered on and off at rapid intervals, leaving marks on the cd surface which represent bits.
A blank cd is, in its most part, a piece of plastic made by squeezing 4 layers together. The upper layer is the protective coating of the cd. The reflective layer, which is golden or silver, follows, followed by a layer or organic dye, which is the one where information is written onto. Finally comes a layer of polycarbonate, which acts as a guide for the spiral trajectory followed by the laser beam.
The dye used is heated by the laser beam at temperatures of more than
300C, and as a result reflectivity of the cd surface changes. For the
whole process to be successful, great precision is required!