Beam address optical storage head

• US 3,877,784 A
• Filed: 09/20/1973
• Issued: 04/15/1975
• Est. Priority Date: 09/20/1973
• Status: Expired due to Term

• Current Assignee: Burn Jeng Lin
• Original Assignee: Burn Jeng Lin
• Inventors: Lin, Burn Jeng
• Primary Examiner(s): Corbin, John K.
• Application Number:
  US05/399,007
• Time in Patent Office: 572 Days
• Field of Search: 350/96WG,96C,151,162R
• US Class Current: 385/33
• CPC Class Codes: G02B 27/42 Diffraction optics , i.e. systems including a diffractive element being designed for providing a diffractive effectG02B27/60 takes precedence
• CPC Class Codes: G02B 27/4238 in optical recording or readout devices optical pick-up devices such as for CD, DVD or BD reader or recorder using diffraction optics G11B7/1353
• CPC Class Codes: G02F 1/335 having an optical waveguide structure
• CPC Class Codes: G11B 11/10 using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
• CPC Class Codes: G11B 7/122 Flying-type heads, e.g. analogous to Winchester type in magnetic recording
• CPC Class Codes: G11B 7/14 specially adapted to record on, or to reproduce from, more than one track simultaneously
• CPC Class Codes: G11C 13/04 using optical elements ; using other beam accessed elements, e.g. electron or ion beam

Abstract

The beam address optical storage head uses the high resolution focusing properties which result from near-field diffraction of a slit or its equivalent. The slit is flown over the recording media much like a magnetic head to provide high bit densities along the track. The head may comprise a single focusing element or a plurality of focusing elements with beam-steering. Fully integrated optical head structures fabricated using techniques similar to those used for integrated semiconductor circuitry are disclosed. Illumination for the head may be provided by an integrated source or an outside source coupled to the integrated head. The focusing structure for the head in the various embodiments may take the form of metallic or dielectric wave guides or a stack of thin slits.

Claims

1. An optical transducer providing high resolution focusing on a record-track surface movable relative to said transducer in an optical storage system, comprising:

illuminating means for providing a monochromatic source of light, slit-optics focusing means for focusing a spot of light smaller than the slit width dimension of said focusing means on said surface, and a thin slit wider than the width of said slit-optics focusing means disposed between said illuminating means and said slitoptics focusing means for focusing the light from said illuminating means on said slit-optics focusing means.

2. An optical transducer as recited in claim 1 wherein said slit-optics focusing means is a metallic wave guide longitudinally aligned with the optical axis of the transducer and having the slit-width thereof oriented in a direction parallel to the direction oF relative motion between the transducer and said surface.

3. An optical transducer as recited in claim 1 wherein said slit-optics focusing means is a dielectric wave guide longitudinally aligned with the optical axis of the transducer and having the slit-width thereof oriented in a direction parallel to the direction of relative motion between the transducer and said surface.

4. An optical transducer as recited in claim 1 wherein said slit-optics focusing means is a stack of thin slits disposed periodically along the optical axis of the transducer and separated by a distance approximately equal to the focal length of each slit, the slit-width dimensions of the slits being oriented in a direction parallel to the direction of relative motion between the transducer and said surface.

5. An optical transducer as recited in claim 1 wherein said slit-optics focusing means comprises a plurality of metallic wave guides in an array longitudinally aligned in parallel with the optical axis of the transducer and the slit-widths oriented in a direction parallel to the direction of relative motion between the transducer and said surface, wherein each of said wave guides in said array corresponds to a different position or track on said surface.

6. An optical transducer as recited in claim 5 wherein said wave guides are separated from one another by metallic separating walls.

7. An optical transducer as recited in claim 5 wherein said plurality of wave guides are comprised of a single, elongated slit.

8. An optical transducer as recited in claim 5 further comprising beam-steering means disposed between said illuminating means and said coupling means for selectively directing light from said illuminating means to a selected one of said plurality of wave guides thereby permitting selection of a particular track on said surface.

9. An optical transducer as recited in claim 8 wherein said beam-steering means includes an acoustic transducer disposed to project an acoustical wave perpendicular to the optical axis of said transducer.

10. An optical transducer as recited in claim 1 wherein said slit-optics focusing means comprises a plurality of dielectric wave guides in an array longitudinally aligned and parallel with the optical axis of the transducer and the slit-widths oriented in a direction parallel to the direction of relative motion between the transducer and said surface, wherein each of said wave guides in said array corresponds to a different position or track on said surface.

11. An optical transducer as recited in claim 10 wherein said wave guides are separated from one another by metallic separating walls.

12. An optical transducer as recited in claim 10 wherein said wave guides are comprised of a single elongated dielectric wave guide.

13. An optical transducer as recited in claim 10 further comprising beam-steering means disposed between said illuminating means and said coupling means for selectively directing light from said illuminating means to a selected one of said plurality of wave guides thereby permitting selection of a particular track on said surface.

14. An optical transducer as recited in claim 13 wherein said beam-steering includes an acoustic transducer disposed to project an acoustical wave perpendicular to the optical axis of said transducer.

15. An optical transducer as recited in claim 1 wherein said illuminating means comprises:

a source of monochromatic light, and a dielectric wave guide into which light from said source is coupled for conducting said light to said coupling means.

16. An optical transducer as recited in claim 15 further comprising an integrated condensing lens formed in said wave guide.

17. An optical transducer as recited in claim 16 wherein said source is external and comprises:

a laser, an optical coupler disposed to couple light into said wave guide, and a collimating lens focusing light from said laser onto said optical coupler.

18. An optical transducer as recited in claim 16 wherein said source is integrated with said dielectric wave guide and comprises a semiconductor laser junction.

19. An optical transducer as recited in claim 1 for reading bits of information recorded in said surface further comprising detecting means disposed on the opposite side of said surface for detecting light when a recorded bit is illuminated by said focusing means.

20. An optical transducer as recited in claim 19 wherein said detecting means comprises:

analyzer means oriented to pass light the polarization of which has been changed by passing through said surface, and a photo-detector for sensing the light passed by said analyzer means.

21. An optical transducer as recited in claim 1 wherein at least said slit-optics focusing means and said coupling means are constructed using integrated optics techniques.

22. An optical transducer providing high resolution focusing comprising:

means for receiving monochromatic light, slit-optics focusing means for focusing a spot of light smaller than the slit width dimension of said focusing means, and a thin slit wider than the width of said slit-optics focusing means disposed between said light receiving means and said slit-optics focusing means for focusing the received light on said slit-optics focusing means.

23. An optical transducer as recited in claim 22 wherein said slit-optics focusing means is a metallic waveguide longitudinally aligned with the optical axis of the transducer.

24. An optical transducer as recited in claim 22 wherein said slit-optics focusing means is a dielectric waveguide longitudinally aligned with the optical axis of the transducer.

25. An optical transducer as recited in claim 22 wherein said slit-optics focusing means is a stack of thin slits disposed periodically along the optical axis of the transducer and separated by a distance approximately equal to the focal length of each slit.

26. An optical transducer as in claim 22 wherein said means for receiving light is an optical grating.

27. An optical transducer as in claim 22 wherein said slit optics means comprises a plurality of waveguides and said coupling means includes means for selectively steering light into individual ones of said waveguides.

28. An optical transducer as in claim 27 wherein said steering means includes an acoustic transducer disposed to project an acoustical wave perpendicular to the optical axes of said transducer.

29. An optical transducer providing high resolution focusing, comprising:

illuminating means for providing monochromatic light, slit-optics focusing means for focusing a spot of light smaller than the slit width dimension of said focusing means, and a thin slit wider than the width of said slit-optics focusing means disposed between said illuminating means and said slit-optics focusing means for focusing the light from said illuminating means on said slit-optics focusing means.

30. An optical transducer as recited in claim 29 wherein said slit-optics focusing means is a metallic waveguide longitudinally aligned with the optical axis of the transducer.

31. An optical transducer as recited in claim 29 wherein said slit-optics focusing means is a dielectric waveguide longitudinally aligned with the optical axis of the transducer.

32. An optical transducer as recited in claim 29 wherein said slit-optics focusing means is a stack of thin slits disposed periodically along the optical axis of the transducer and separated by a distance approximately equal to the focal length of each slit.

33. An optical transducer as in claim 29 wherein said means for receiving light is an optical grating.

34. An optical transducer as in claim 33 wherein said slit optics means comprises a plurality of waveguides and said coupling means includes means for selectively steering light into individual ones of said waveguides.

35. An optical transducer as in claim 34 wherein said steering means includes an acoustic transducer disPosed to project an acoustical wave perpendicular to the optical axes of said transducer.