Optical element, optical head, optical recording reproducing apparatus and optical recording/ reproducing method

• US 7,034,980 B2
• Filed: 08/15/2005
• Issued: 04/25/2006
• Est. Priority Date: 07/24/2000
• 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: Wada, Hidenori, Komma, Yoshiaki, Kadowaki, Shin-ichi, Yamamoto, Hiroaki, Ogata, Daisuke, Nishino, Seiji, Saimi, Tetsuo
• Primary Examiner(s): Ben, Loha
• Application Number:
  US11/203,914
• Publication Number:
  US 20050286385A1
• Time in Patent Office: 253 Days
• Field of Search: 359244-246, 359252-254, 359/238, 359/265, 359/273, 359/275, 359/315, 359/316, 359/322, 359/323, 369/44.23, 369/94, 369/44.24, 369/112.02, 369/112.03, 369/53.12, 369/44.32, 349/12, 349/16, 349/146, 349/193, 349/200, 349/202, 428/64.1
• US Class Current: 359/254
• CPC Class Codes: G02F 2203/18 adaptive optics, e.g. wavefront correction
• CPC Class Codes: G11B 2007/0013 for carriers having multiple discrete layers
• CPC Class Codes: G11B 7/0948 specially adapted for detection and avoidance or compensation of imperfections on the carrier, e.g. dust, scratches, dropouts G11B7/095 takes precedence
• CPC Class Codes: G11B 7/1369 Active plates, e.g. liquid crystal panels or electrostrictive elements
• CPC Class Codes: G11B 7/13925 active, e.g. controlled by electrical or mechanical means
• CPC Class Codes: G11B 7/13927 during transducing, e.g. to correct for variation of the spherical aberration due to disc tilt or irregularities in the cover layer thickness

Abstract

The invention presents an optical element with which an optical head can be configured, in which there is little deterioration of the correctional effect when the objective lens shifts, as well as an optical head and an optical recording/reproducing apparatus using such an optical element. The invention also presents a novel optical recording/reproducing apparatus and optical recording/reproducing method. The optical element, includes a first voltage application electrode 13, a first opposing electrode 17 arranged in opposition to the first voltage application electrode 13, and a first phase changing layer 15 arranged between the first voltage application electrode 13 and the first opposing electrode 17. By changing a voltage between the first voltage application electrode 13 and the first opposing electrode 17, a phase that converts plane waves into spherical waves is imparted on light that is incident on the first phase changing layer 15.

Claims

1. An optical element, comprising:

a first voltage application electrode;

a first opposing electrode arranged in opposition to the first voltage application electrode; and

a first phase changing layer arranged between the first voltage application electrode and the first opposing electrode;

wherein, by changing a voltage between the first voltage application electrode and the first opposing electrode, a phase that converts plane waves into spherical waves is imparted on light that is incident on the first phase changing layer.

2. The optical element according to claim 1, wherein at least one electrode selected from the first voltage application electrode and the first opposing electrode is arranged on a curved surface.

3. The optical element according to claim 1, wherein the first phase changing layer is made of a material whose refractive index changes when applying a voltage.

4. The optical element according to claim 3, wherein the first phase changing layer is made of a liquid crystal.

5. The optical element according to claim 1, wherein the first phase changing layer is made of a material whose volume changes when subjected to a voltage.

6. The optical element according to claim 5, wherein the first phase changing layer is made of PLZT.

7. The optical element according to claim 1, wherein the first voltage application electrode includes a plurality of segment electrodes.

8. The optical element according to claim 1, further comprising:

a second voltage application electrode;

a second opposing electrode arranged in opposition to the second voltage application electrode; and

a second phase changing layer arranged between the second voltage application electrode and the second opposing electrode;

wherein, by changing a voltage between the second voltage application electrode and the second opposing electrode, a phase that converts plane waves into spherical waves is imparted on polarized light that is perpendicular to the polarization of the light that is incident on the first phase changing layer.

9. The optical element according to claim 8, wherein at least one electrode selected from the second voltage application electrode and the second opposing electrode is arranged on a curved surface.

10. The optical element according to claim 8, wherein the second phase changing layer is made of a material whose refractive index changes when applying a voltage between the second voltage application electrode and the second opposing electrode.

11. The optical element according to claim 8, wherein the second phase changing layer is made of a material whose volume changes when applying a voltage between the second voltage application electrode and the second opposing electrode.

12. The optical element according to claim 8, wherein the second voltage application electrode includes a plurality of segment electrodes.

13. An optical head for recording or reproducing signals on an optical recording medium, the optical head comprising:

a light source;

an optical element arranged between the optical recording medium and the light source; and

an objective lens arranged between the optical recording medium and the optical element;

wherein the optical element is the optical element according to claim 1.

14. The optical head according to claim 13, further comprising an N/4 wavelength plate (wherein N is an odd number of one or greater) arranged between the optical element and the objective lens.

15. An optical recording/reproducing apparatus for recording or reproducing signals on an optical recording medium, the optical recording/reproducing apparatus comprising:

an optical head for recording or reproducing signals on an optical recording medium, the optical head comprising;

a light source;

an optical element arranged between the optical recording medium and the light source; and

an objective lens arranged between the optical recording medium and the optical element;

wherein the optical element is the optical element according to claim 1.