Abstract: An optical data recording and reproducing apparatus including an objective lens holder which holds an objective lens for converging laser light onto an optical disc, a tracking mechanism which drives the objective lens holder in a tracking direction of the optical disc, and a displacement detecting mechanism which detects the displacement of the objective lens holder effected by the tracking mechanism. The displacement detecting mechanism has photosensors which have light emitters and light receivers. The light receivers are located further from the optical disc than the light emitters. The photosensors are supported on a single sensor holder.

Abstract: An optical data recording and reproducing apparatus including an objective lens for converging light onto an optical disc, and a lens holder which supports the objective lens. The lens holder has a circular opening and a lens holding surface provided on a periphery of the circular opening. One of either the objective lens or the lens holding surface of the lens holder has a symmetrical tapered surface which is adapted to come into contact with the other of either the lens holding surface or objective lens, respectively.