Optical pick-up head apparatus wherein hollographic optical element and photodetector are formed on semiconductor substrate

• US 5,293,038 A
• Filed: 03/23/1993
• Issued: 03/08/1994
• Est. Priority Date: 04/08/1992
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Komma, Yoshiaki, Kadowaki, Shinichi, Nishino, Seiji
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): LE, QUE TAN
• Application Number:
  US08/035,777
• Time in Patent Office: 350 Days
• Field of Search: 250/216, 250/201.5, 250/201.2, 250/201.1, 250/202, 250/201.6, 369/44.23, 369/44.25, 369/44.37, 369/44.41, 369/44.14, 359/212, 359/218, 359/217, 359/214, 372/46, 372/50
• US Class Current: 250/216
• CPC Class Codes: G11B 7/123 Integrated head arrangements, e.g. with source and detectors mounted on the same substrate
• CPC Class Codes: G11B 7/1353 Diffractive elements, e.g. holograms or gratings diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44

Abstract

An optical pick-up head apparatus to be used for recording and reproducing or erasing optical information on and from an optical storage medium. The head apparatus comprises a semiconductor laser source, a reflector, a reflection type holographic optical element and a photodetector. A laser beam emitted from the semiconductor laser source is incident through the reflector on the reflection type holographic optical element so as to be incident through an objective lens on the optical storage medium. The laser beam reflected and diffracted on the optical storage medium advances along the same path in the opposite direction to be incident on the reflection type holographic optical element to become diffraction beams. The diffraction beams are incident on the photodetector after being reflected on the reflector so as to obtain a focusing error signal, tracking error signal and information signal. The reflection type holographic optical element and the photodetector are formed on one semiconductor substrate, and the semiconductor laser source is disposed to be close to the photodetector on the semiconductor substrate. Due to this arrangement, the head apparatus can easily and accurately be assembled without the positional adjustment of the reflection type holographic optical element or the photodetector, thereby improving the mass productivity of the head apparatus.

Claims

1. An optical pick-up head apparatus comprising:

a semiconductor laser source for emitting a coherent or semimonochromatic beam;

first reflection means for reflecting said beam from said semiconductor laser source to change the advancing direction of said beam therefrom;

second reflection means for reflecting the beam reflected on said first reflection means to change the advancing direction thereof;

third reflection means for reflecting the beam reflected on said second reflection means to change the advancing direction thereof;

a converging optical system for receiving the beam reflected on said third reflection means to focus the beam on a microscopic spot on an optical storage medium;

a reflection type holographic optical element for receiving the beam reflected and diffracted on said optical storage medium to generate a diffraction beam; and

a photodetector having a plurality of photodetecting elements to receive said diffraction beam from said reflection type holographic optical element to generate a photoelectric conversion signal,

wherein said laser source is formed on a first semiconductor substrate so that said beam from said laser source is emitted in a direction substantially parallel to a surface of said first semiconductor substrate, said reflection type holographic optical element is formed in said third reflection means, said diffraction beam from said reflection type holographic optical element is incident on said photodetector after being reflected on said second reflection means, said first reflection means, said third reflection means and said photodetector are formed on a second semiconductor substrate, a light-receiving surface of said photodetector is arranged to be substantially parallel to a surface of said second semiconductor substrate, and said surface of said first semiconductor substrate is disposed to be substantially parallel to said surface of said second semiconductor substrate.

2. An optical pick-up head apparatus as claimed in claim 1, wherein a diffraction grating is disposed in an optical path of the beam from said semiconductor laser source to said reflection type holographic optical element.

3. An optical pick-up head apparatus as claimed in claim 1, wherein a reflection type diffraction grating is provided in said second reflection means;

4. An optical pick-up head apparatus as claimed in claim 1, further comprising a second photodetector disposed on said second semiconductor substrate for receiving a portion of said beam from said semiconductor laser source which is not reflected and diffracted on said optical storage medium.

5. An optical pick-up head apparatus as claimed in claim 4, wherein said second photodetector is disposed to surround said reflection type holographic optical element.

6. An optical pick-up head apparatus comprising:

a semiconductor laser source for emitting a coherent or semimonochromatic beam;

first reflection means for reflecting said beam from said semiconductor laser source to change the advancing direction of said beam therefrom;

second reflection means for reflecting the beam reflected on said first reflection means to change the advancing direction thereof;

third reflection means for reflecting the beam reflected on said second reflection means to change the advancing direction thereof;

a converging optical system for receiving the beam reflected on said third reflection means to focus the beam on a microscopic spot on an optical storage medium;

a reflection type holographic optical element for receiving the beam reflected and diffracted on said optical storage medium to generate a diffraction beam; and

a photodetector having a plurality of photodetecting elements to receive said diffraction beam from said reflection type holographic optical element to generate a photoelectric conversion signal,

wherein said laser source and said first reflection means are formed on a first semiconductor substrate, said beam from said laser source is emitted in a direction substantially parallel to a surface of said first semiconductor substrate, said reflection type holographic optical element is formed in said third reflection means, said diffraction beam from said reflection type holographic optical element is incident on said photodetector after being reflected on said second reflection means, said third reflection means and said photodetector are formed on a second semiconductor substrate, a light-receiving surface of said photodetector is arranged to be substantially parallel to a surface of said second semiconductor substrate, and said surface of said first semiconductor substrate is disposed to be substantially parallel to said surface of said second semiconductor substrate.

7. An optical pick-up head apparatus as claimed in claim 6, wherein a diffraction grating is disposed in an optical path of the beam from said semiconductor laser source to said reflection type holographic optical element.

8. An optical pick-up head apparatus as claimed in claim 6, wherein a reflection type diffraction grating is provided in said second reflection means.

9. An optical pick-up head apparatus as claimed in claim 6, further comprising a second photodetector disposed on said second semiconductor substrate for receiving a portion of said beam from said semiconductor laser source which is not reflected and diffracted on said optical storage medium.

10. An optical pick-up head apparatus as claimed in claim 9, wherein said second photodetector is disposed to surround said reflection type holographic optical element.

11. An optical pick-up head apparatus comprising:

a semiconductor laser source for emitting a coherent or semimonochromatic beam;

first reflection means for reflecting said beam from said semiconductor laser source to change the advancing direction of said beam therefrom;

second reflection means for reflecting the beam reflected on said first reflection means to change the advancing direction thereof;

third reflection means for reflecting the beam reflected on said second reflection means to change the advancing direction thereof;

a converging optical system for receiving the beam reflected on said third reflection means to focus the beam on a microscopic spot on an optical storage medium;

a reflection type holographic optical element for receiving the beam reflected and diffracted on said optical storage medium to generate a diffraction beam; and

a photodetector having a plurality of photodetecting elements to receive said diffraction beam from said reflection type holographic optical element to generate a photoelectric conversion signal,

wherein said laser source, said first reflection means, said third reflection means and said photodetector are formed on one semiconductor substrate, said beam from said laser source is emitted in a direction substantially parallel to a surface of said semiconductor substrate, said reflection type holographic optical element is formed in said third reflection means, said diffraction beam from said reflection type holographic optical element is incident on said photodetector after being reflected on said second reflection means, and a light-receiving surface of said photodetector is arranged to be substantially parallel to a surface of said semiconductor substrate.

12. An optical pick-up head apparatus as claimed in claim 11, wherein a diffraction grating is disposed in an optical path of the beam from said semiconductor laser source to said reflection type holographic optical element.

13. An optical pick-up head apparatus as claimed in claim 11, wherein a reflection type diffraction grating is provided in said second reflection means.

14. An optical pick-up head apparatus as claimed in claim 11, further comprising a second photodetector disposed on said semiconductor substrate for receiving a portion of said beam from said semiconductor laser source which is not reflected and diffracted on said optical storage medium.

15. An optical pick-up head apparatus as claimed in claim 14, wherein said second photodetector is disposed to surround said reflection type holographic optical element.

16. An optical pick-up head apparatus comprising:

a semiconductor laser source for emitting a coherent or semi-monochromatic beam;

first reflection means for reflecting said beam from said semiconductor laser source to change the advancing direction of said beam therefrom;

second reflection means for reflecting the beam reflected on said first reflection means to change the advancing direction thereof;

a converging optical system for receiving the beam reflected on said second reflection means to focus the beam on a microscopic spot on an optical storage medium;

a reflection type holographic optical element for receiving the beam reflected and diffracted on said optical storage medium to generate a diffraction beam; and

a photodetector having a plurality of photodetecting elements to receive said diffraction beam from said reflection type holographic optical element to generate a photoelectric conversion signal,

wherein said reflection type holographic optical element is formed in said second reflection means, said diffraction beam from said reflection type holographic optical element is incident on said photodetector after being reflected on said first reflection means, said laser source is formed on a first semiconductor substrate, said beam from said laser source is emitted in a direction substantially parallel to a surface of said first semiconductor substrate, said second reflection means and said photodetector are formed on a second semiconductor substrate, a light-receiving surface of said photodetector is arranged to be substantially parallel to a surface of said second semiconductor substrate, and said first semiconductor substrate is disposed on said second semiconductor substrate so that said surface of said first semiconductor substrate is substantially parallel to said surface of said second semiconductor substrate.

17. An optical pick-up head apparatus as claimed in claim 16, wherein a diffraction grating is disposed in an optical path of the beam from said semiconductor laser source to said reflection type holographic optical element.

18. An optical pick-up head apparatus as claimed in claim 16, wherein a reflection type diffraction grating is provided in said first reflection means.

19. An optical pick-up head apparatus as claimed in claim 16, further comprising a second photodetector disposed on said second semiconductor substrate for receiving a portion of said beam from said semiconductor laser source which is not reflected and diffracted on said optical storage medium.

20. An optical pick-up head apparatus as claimed in claim 19, wherein said second photodetector is disposed to surround said reflection type holographic optical element.

21. An optical pick-up head apparatus comprising:

a semiconductor laser source for emitting a coherent or semi-monochromatic beam;

first reflection means for reflecting said beam from said semiconductor laser source to change the advancing direction of said beam therefrom;

second reflection means for reflecting the beam reflected on said first reflection means to change the advancing direction thereof;

a converging optical system for receiving the beam reflected on said second reflection means to focus the beam on a microscopic spot on an optical storage medium;

a reflection type holographic optical element for receiving the beam reflected and diffracted on said optical storage medium to generate a diffraction beam; and

a photodetector having a plurality of photodetecting elements to receive said diffraction beam from said reflection type holographic optical element to generate a photoelectric conversion signal,

wherein said reflection type holographic optical element is formed in said second reflection means, said diffraction beam from said reflection type holographic optical element is incident on said photodetector after being reflected on said first reflection means, said laser source, said second reflection means and said photodetector are formed on one semiconductor substrate, said beam from said laser source is emitted in a direction substantially parallel to a surface of said semiconductor substrate, and a light-receiving surface of said photodetector is arranged to be substantially parallel to a surface of said semiconductor substrate.

22. An optical pick-up head apparatus as claimed in claim 21, wherein a diffraction grating is disposed in an optical path of the beam from said semiconductor laser source to said reflection type holographic optical element.

23. An optical pick-up head apparatus as claimed in claim 21, wherein a reflection type diffraction grating is provided in said first reflection means.

24. An optical pick-up head apparatus as claimed in claim 21, further comprising a second photodetector disposed on said semiconductor substrate for receiving a portion of said beam from said semiconductor laser source which is not reflected and diffracted on said optical storage medium.

25. An optical pick-up head apparatus as claimed in claim 24, wherein said second photodetector is disposed to surround said reflection type holographic optical element.