Optical Record
Data hidden on a disc
Turn the large disc and listen to the sound recording. You can create your own recording if you encode the individual tones in the prepared track by colouring the relevant fields (bits). An optical record medium is usually a disc with a diameter of 12 centimetres, having a hole in the middle with a diameter of 1.5 centimetres. Unlike hard disks, the data is not entered in concentric circles but in a spiral which facilitates a continuous data flow. The data is stored as a sequence of lands (places on which light is reflected) and pits (places where light is dispersed). Data reading is based on the intensity of the reflected laser beam.
