Optical information recording/reproducing apparatus

An optical information recording/-reproducing apparatus which records information on and/or reproduces information from an optical recording medium based on a reflected light beam from the optical recording medium, said optical information recording/reproducing apparatus comprising:

• a light splitting part having a plurality of light splitting stages which split the reflected light beam from the optical recording medium into a plurality of light beams;
• and
• a photodetector unit including a plurality of photodetectors which receive the plurality of light beams from said light splitting part,
• said photodetector unit including a first plurality of photodetectors which receive light beams used to detect a focal error, at least one photodetector which receives a light beam used to detect a tracking error, and a second plurality of photodetectors which receive light beams used to detect optical information recorded on the optical recording medium,
• wherein said light splitting part splits the reflected light beam from the optical recording medium into nine light beams, and said photodetector unit includes five photodetectors which receive the nine light beams.

An optical information recording/reproducing apparatus which records information on and/or reproduces information from an optical recording medium based on a reflected light beam from the optical recording medium, comprising:

• a light splitting part having a plurality of light splitting stages which split the reflected light beam from the optical recording medium into a plurality of light beams;
• and
• a photodetector unit including n photodetectors which receive m light beams output from a final stage of said light splitting part, where m and n are positive integers satisfying m≧n, said n photodetectors of said photodetector unit including a first plurality of photodetectors which are arranged to receive light beams used to detect a focal error, at least one photodetector which is arranged to receive a light beam used to detect a tracking error, and a second plurality of photodetectors which are arranged to receive light beams used to detect optical information recorded on the optical recording medium,
• wherein said at least one photodetector which receives the light beam used to detect the tracking error is not included in said first plurality of photodetectors,
• said light splitting part including an analyzer which splits an incoming light beam into polarized light beams and a composite prism which spatially splits an incoming light beam into a plurality of light beams, said analyzer and said composite prism being arranged in an arbitrary order between the optical recording medium and said photodetector unit.

An optical information recording/reproducing apparatus which records information on and/or reproduces information from an optical recording medium based on a reflected light beam from the optical recording medium, comprising:

• a light splitting part having a plurality of light splitting stages which split the reflected light beam from the optical recording medium into a plurality of light beams;
• and
• a photodetector unit including n photodetectors which receive m light beams output from a last stage of said light splitting part, where m and n are positive integers satisfying m>n,
• said n photodetectors of said photodetector unit including a plurality of photodetectors which are arranged to receive light beams used to detect a focal error, at least one photodetector which is arranged to receive a light beam used to detect a tracking error, and a plurality of photodetectors which are arranged to receive in common light beams used to detect optical information recorded on the optical recording medium,
• said integers m and n being selected to satisfy one of the conditions m=9 and n=5, and m=15 and n=5.

An optical information recording/reproducing apparatus which records information on and/or reproduces information from an optical recording medium based on a reflected light beam from the optical recording medium, said optical information recording/reproducing apparatus comprising:

• an analyzer;
• a composite prism;
• and
• a photodetector unit, all of which are arranged approximately linearly along a common optical axis of the reflected light beam, said photodetector unit including a plurality of photodetectors,
• wherein said analyzer has a function of splitting the reflected light beam into a plurality of light beams having different polarization directions,
• said composite prism has a plurality of deflection parts for spatially splitting each of the plurality of light beams received from said analyzer into three light beams,
• said photodetector unit receives the light beams deflected by said composite prism and produces a focal error signal, a tracking error signal and an optical signal based on the light beams received by the plurality of photodetectors, and
• the photodetector used for receiving the tracking error signal is not used for producing the focal error signal or the optical signal.