Optical information recording/reproduction apparatus including an integrated photodetector used in the detection of focusing and/or tracking error signals

摘要

An optical information recording/reproduction apparatus includes a radiation device for radiating a light beam onto an information recording medium, a converging device for converging the light beam reflected by the information recording medium, a first device for splitting the converged light beam into two light beams, a second device for guiding the two split light beams onto a single light- receiving surface, which can receive the two light beams, via optical paths having different optical path lengths, the second device guiding the two light beams, so that one of the two split light beams is projected onto the light- receiving surface at a position before the light beam passes a convergent point thereof, and the other light beam is projected onto the light- receiving surface at a position after the light beam passes a convergent point thereof, an integrated photodetector including at least two photodetection regions for receiving the light beams on the light- receiving surface, a size, in one direction, of each of the photodetection regions of the photodetector being set to be smaller than a beam spot size on the light-receiving surface in an in- focus state and device for detecting, focusing error signals from the light beams on the light-receiving surface, by the photodetection regions.