Method and apparatus for forming a light spot smaller than a theoretical limit for high density recording

• US 5,793,407 A
• Filed: 07/27/1995
• Issued: 08/11/1998
• Est. Priority Date: 12/26/1994
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Tae-seok, Yoo, Jang-hoon, Lee, Chul-woo
• Primary Examiner(s): Reinhart, Mark J.
• Application Number:
  US08/507,914
• Time in Patent Office: 1,111 Days
• Field of Search: 347/258, 347/256, 347/241, 347/134, 359/566, 359/641, 359/719, 359/742
• US Class Current: 347/258
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G02B 27/58 Optics for apodization or superresolution; Optical synthetic aperture systems
• CPC Class Codes: G11B 2007/13727 Compound lenses, i.e. two or more lenses co-operating to perform a function, e.g. compound objective lens including a solid immersion lens, positive and negative lenses either bonded together or with adjustable spacing
• CPC Class Codes: G11B 7/122 Flying-type heads, e.g. analogous to Winchester type in magnetic recording
• CPC Class Codes: G11B 7/1367 Stepped phase plates
• CPC Class Codes: G11B 7/1381 Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops G11B7/1353 - G11B7/1369 take precedence
• CPC Class Codes: G11B 7/1387 using the near-field effect

Abstract

A high density recording method for performing high density recording by reducing a light spot size in an optical pickup for recording information by scanning an optical disk with the light spot, spatially controlling the phase or the intensity of light being focused within the optical focal length of an objective lens by employing a diffraction optical element so as to form on the optical disk a light spot whose diameter is reduced according to the width of the portion for controlling the phase or intensity of the light. The distribution of the optical intensity is variable depending on the distance between the diffraction optical element and the optical disk, to thereby enable theoretically forming a limitlessly small light spot, and actually, greatly increase the recording capacity. The diffraction optical element can be used as a floating slider in an optical pickup having a swing arm.

Claims

1. A high density optical recording method for performing high density optical recording comprising the steps of:

focusing light from a light source using an objective lens to form a light spot on an optical recording medium; and

diffracting said light being focused by said objective lens by employing a diffraction optical element located between the objective lens and the optical recording medium without intervening optical elements for controlling one of the phase and the intensity of said light being focused by said objective lens.

5. A high density optical recording method according to claim 1, further comprising the step of providing a supporting means to hold said diffraction optical element.

6. A high density optical recording method according to claim 5, wherein said the step of providing a supporting means includes forming a swing arm to hold said diffraction optical element.

2. A high density optical recording method for performing high density optical recording comprising the steps of:

focusing light from a light source using an objective lens to form a light spot on an optical recording medium; and

diffracting said light being focused by said objective lens by employing a phase apodizer placed between said objective lens and optical recording medium so as to change the phase of said light, said phase apodizer having a groove with a predetermined width and depth.

4. A high density optical recording method according to claim 2, wherein said phase apodizer is placed within the optical focal length of said objective lens.

3. A high density optical recording method for performing high density optical recording comprising the steps of:

focusing light from a light source using an objective lens to form a light spot on an optical recording medium; and

diffracting said light being focused by said objective lens by employing a phase apodizer placed within the optical focal length of said objective lens.

7. A high density optical recording apparatus including:

a light source;

an objective lens for focusing a light spot from light generated from said light source onto an optical recording medium; and

a diffraction optical element for spatially controlling one of the phase and the intensity of said light being focused by said objective lens to diffract said light being focused by said objective lens, said diffraction optical element being located between the objective lens and the optical recording medium without intervening optical elements.

11. A high density optical recording apparatus according to claim 7, which includes supporting means attached to said diffraction optical element.

12. A high density optical recording apparatus according to claim 11, wherein said supporting means having a swing arm supporting said diffraction optical element.

8. A high density optical recording apparatus including:

a light source;

an objective lens for focusing a light spot from light generated from said light source onto an optical recording medium; and

a diffraction optical element for spatially controlling one of the phase and the intensity of said light being focused by said objective lens to diffract said focused by said objective lens, wherein said diffraction optical element includes a phase apodizer having a groove with a predetermined width and depth placed between said objective lens and optical recording medium so as to change the phase of said light.

10. A high density optical recording apparatus according to claim 8, wherein said phase apodizer is placed within the optical focal length of said objective lens.

9. A high density optical recording apparatus including:

a light source;

an objective lens for focusing a light spot from light generated from said light source onto an optical recording medium; and

a diffraction optical element for spatially controlling one of the phase and the intensity of said light being focused by said objective lens to diffract said light being focused by said objective lens, wherein said diffraction optical element includes a phase apodizer placed within the optical focal length of said objective lens.

13. A high density optical recording apparatus including a light source, an optical means for focusing a light generated from the light source onto an optical recording medium and receiving reflected light from said optical recording medium, a swing arm for supporting said optical means and an actuator for rotating said swing arm, said high density optical recording apparatus comprising a diffraction optical element supported by said swing arm so as to face said optical recording medium and optically combined with said optical means so as to spatially control one of the phase and the intensity of the light being focused by said optical means onto said optical recording medium.

14. A high density optical recording apparatus according to claim 13, wherein said diffraction optical element is a phase apodizer having a groove with a predetermined width and depth on a surface thereof facing said optical recording medium so as to change the phase of said light.

15. A high density optical recording apparatus according to claim 14, wherein said groove is formed in a direction in which said swing arm rotates so that said phase apodizer floats above said optical recording medium by an air cushion formed between said groove and optical recording medium when said swing arm rotates.

16. A high density optical recording apparatus according to claim 13, further comprising an optical fiber wired along said swing arm and for optically connecting said optical means with said light source.

17. A high density optical recording apparatus according to claim 13, wherein said optical means comprises a mirror having a light entrance surface and a light exit surface which are perpendicular to each other and a reflecting surface formed by expanding peripheral portions of said light entrance surface and light emitting surface and for reflecting light passing through said light entrance surface to be focused onto said optical recording medium via said light exit surface.

18. A high density optical recording apparatus according to claim 16, wherein said optical means comprises a mirror having a light entrance surface and a light exit surface which are perpendicular to each other and a reflecting surface formed by expanding peripheral portions of said light entrance surface and light emitting surface and for reflecting light passing through said light entrance surface to be focused onto said optical recording medium via said light exit surface.

19. A high density optical recording apparatus according to claim 17, wherein said reflecting surface is spherical, non-spherical or oval.

20. A high density optical recording apparatus according to claim 18, wherein said reflecting surface is spherical, non-spherical or oval.