Optical information recording-reproducing apparatus in which the relative position of a primary beam and secondary beams on recording medium is varied during recording and reproduction of information

Claim 1

An optical information recording-reproducing apparatus comprising: a light source; grating means for splitting a beam from said light source into a primary beam and at least two secondary beams; an optical system for applying the primary beam and the secondary beams to a recording medium; means for selectively carrying out an information recording on the recording medium in the form of an information track by the primary beam and a reproduction of the recorded information from the information track; means for detecting the secondary beams modulated by the recording medium to obtain a tracking signal; means for effecting tracking of the primary beam and the secondary beams according to the tracking signal; and means for varying a relative position of the primary beam and the secondary beams on the recording medium between times of the information recording and the information reproduction so that at least two of the secondary beams are applied to positions different widthwisely of the information track and not applied to a guide track adjacent to the information track being and not applied to a guide track adjacent to the information track scanned by the primary beam, at the time of the information reproduction, and that at least a part of at least one of the secondary beams is applied to said guide track adjacent to the information track being formed by the primary beam, at the time of the information recording.