| 摘要 |
The reading-out device is intended to allow centring errors to be detected by means of as small as possible number of additional optical elements. The read-out beam (b) of a helium-neon laser (6) is reflected from a mirror (9) to a system of lens (11). A radiation spot is produced on the surface (2) of the information structure of the recording carrier (1). The read-out beam (b) reflected from the information structure is reflected by a semi-transparent mirror (8) to a radiation-sensitive detection system (12). A deviation between the centre of a read-out spot projected on the information structure and the centre line of this track to be read out is established using the detection system (12). With the aid of the detection system (12), a reference signal is obtained, which is used for correcting the position of the read-out spot with respect to the track to be read out. The detection system (12) is formed by four radiation-sensitive detectors. <IMAGE> |
