OPTICALLY READABLE RECORD CARRIER

摘要

A record carrier (40) comprises a radiation-sensitive layer (43) upon a disc-shaped substrate (42) and is provided with an information-recording area arranged in accordance with a spiral-shaped or concentric pattern of preformed tracks (41). The track exhibits a track modulation in the form of a radial wobble whose frequency is modulated with a position-information signal (Ip). Further, an apparatus (1) is disclosed for forming the track pattern during the manufacture of the record carrier (40). When an information signal (Vi) is recorded on the record carrier (40) and the recorded signal is read an FM demodulation device (60) recovers the position-information signal Ip from the variations in the scanning beam (54, 54a) produced by the track modulation. Moreover, a clock signal for the purpose of scanning-velocity control is recovered from these variations in the scanning beam.