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

An optical information recording/reproducing apparatus comprising:

• radiation means for radiating a light beam onto an information recording medium;
• converging means for converging the light beam from the information recording medium;
• means for splitting the converged light beam into two light beams;
• guiding means for guiding the two split light beams onto a single light-receiving surface of an integrated photodetector, which can receive the two split light beams, via optical paths having different optical path lengths, said guiding means guiding the two split light beams, so that one of the two split light beams is projected onto said light-receiving surface at a position before the light beam passes a convergent point thereof, and the other light beam is projected onto said light-receiving surface at a position after the light beam passes a convergent point thereof;
• said integrated photodetector having two photodetection areas each having first, second and third regions, corresponding to the respective light beams, so that said light-receiving surface thereof receives the respective light beams;
• means for detecting a focusing error signal by adding signals from respective ones of said first and second regions corresponding to the respective light beams and executing a differential operation for the two added signals corresponding to the respective light beams;
• means for detecting a tracking error signal by executing a differential operation for signals from respective ones of said first and second regions corresponding to the respective light beams to generate respective push-pull signals and executing a differential operation for the respective push-pull signals corresponding to the respective light beams;
• and
• means for reproducing information recorded on the recording medium by executing a differential operation for signals from respective ones of said first, second and third regions.