Adaptive optics using the electrooptic effect

• US 5,212,583 A
• Filed: 01/08/1992
• Issued: 05/18/1993
• Est. Priority Date: 01/08/1992
• Status: Expired due to Fees

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Youmans, Bruce R., Chang, David B., Shih, I-Fu, Vali, Victor
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US07/818,315
• Time in Patent Office: 496 Days
• Field of Search: 359/245, 359/252, 359/254, 359/257, 359/315, 359/319
• US Class Current: 359/245
• CPC Class Codes: G02F 1/03 based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect G02F1/061 takes precedence
• CPC Class Codes: G02F 1/0305 Constructional arrangements G02F1/0327 - G02F1/05 take precedence
• CPC Class Codes: G02F 1/29 for the control of the position or the direction of light beams, i.e. deflection
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: G02F 2201/12 electrode
• CPC Class Codes: G02F 2202/20 LiNbO3, LiTaO3
• CPC Class Codes: G02F 2203/18 adaptive optics, e.g. wavefront correction
• CPC Class Codes: G02F 2203/24 beam steering
• CPC Class Codes: G02F 2203/28 focussing or defocussing

Abstract

An adaptive electroopical lens system for use in optical data storage systems, optical phased arrays, laser or other optical projectors, and raster scanning devices, and the like. The invention provides an electrooptical means for scanning an optical beam or moving an optical storage or retrieval point. Beam movement is achieved electrooptically, by changing the index of refraction of an electrooptical material by controlling electric fields applied thereto. A plurality of electrodes are disposed on one surface of the electrooptic material and a ground electrode is disposed on the other. The electrodes are adapted to apply electric fields derived from a voltage source to the electroopic material that selectively change its index of refraction and provides for a predetermined index of refraction profile along at least one dimension thereof, thus forming a lens. By appropriately forming the electrode pattern and properly controlling the voltages applied thereto, differing lens shapes may be formed. Since the response times of the electrooptic materials employed in the present invention are on the order of nanoseconds (10^-9 sec) or less, the intrinsic response frequency of the lens system is 10⁹ Hz or more. The present invention thus increases the data storage and retrieval capacity of optical systems in which it is employed.

Claims

1. An adaptive optical lens system comprising:

an electrooptic material having first and second surfaces that are disposed normal to the direction of propagation of an optical beam through the adaptive optical lens system and having an index of refraction that is adjustable in response to an applied electric field;

a first plurality of electrodes disposed on the first surface of the electrooptic material and at least one ground electrode disposed on the second surface of the electrooptic material that are adapted to apply electric fields thereto, which first plurality of electrodes and at least one ground electrode are substantially transparent to the optical beam, which electric fields are adapted to selectively change the index of refraction of the electrooptical material across a first dimension thereof to provide for a first predetermined index of refraction profile along the first dimension and thereby form a lens, and whereby the change in index of refraction across the first dimension is adapted to change the angle at which the optical beam entering the electrooptic lens exits the lens; and

a first voltage source coupled to the first plurality of electrodes and the at least one ground electrode for applying predetermined voltages to the plurality of electrodes to create the first predetermined index of refraction profile in the electrooptic material.

2. The lens system of claim 1 wherein the electrooptic material comprises barium titanate (BaTiO₃).

3. The lens system of claim 1 wherein the electrooptic material comprises lithium niobate (LiNbO₃).

4. The lens system of claim 1 wherein the first plurality of electrodes comprises a plurality of parallel electrodes disposed across the first surface of the electrooptic material.

5. The lens system of claim 1 wherein the first plurality of electrodes comprises a grid of electrodes disposed on the first surface of the electrooptic material in a checkerboard pattern.

6. The lens system of claim 2 wherein the first plurality of electrodes comprises a plurality of parallel electrodes disposed across the first surface of the electrooptic material.

7. The lens system of claim 2 wherein the first plurality of electrodes comprises a grid of electrodes disposed on the first surface of the electrooptic material in a checkerboard pattern.

8. The lens system of claim 3 wherein the first plurality of electrodes comprises a plurality of parallel electrodes disposed across the first surface of the electrooptic material.

9. The lens system of claim 3 wherein the first plurality of electrodes comprises a parallel grid of electrodes disposed on the first surface of the electrooptic material in a checkerboard pattern.

10. The lens system of claim 1 wherein the first voltage source is adapted to provide electric fields in the range of 0 kV/centimeter to 100 kV/centimeter.

11. The lens system of claim 1 wherein the first plurality of electrodes comprises a plurality of spaced apart parallel electrodes disposed on the first surface of the electrooptic material, and wherein the lens system further comprises a second plurality of electrodes comprising a plurality of spaced apart parallel electrodes disposed on the first plurality of electrodes and oriented orthogonal thereto and which are substantially transparent to the optical beam, and a second voltage source coupled to the second plurality of electrodes and the at least one ground electrode for applying predetermined voltages to the second plurality of electrodes to create a second predetermined index of refraction profile in the electrooptic material.

12. An adaptive optical lens system comprising:

an electrooptic material having first and second surfaces that are disposed normal to the direction of propagation of an optical beam through the adaptive optical lens system and having an index of refraction that is adjustable in response to an applied electric field;

a first plurality of electrodes disposed on the first surface of the electrooptic material and at least one ground electrode disposed on the second surface of the electrooptic material that are adapted to apply electric fields thereto, which electric fields are adapted to selectively change the index of refraction of the electrooptical material across a first dimension thereof to provide for a first predetermined index of refraction profile along the first dimension and thereby form a lens, and whereby the change in index of refraction across the first dimension is adapted to change the angle at which an optical beam entering the electrooptic lens exits the lens;

a second plurality of electrodes comprising a plurality of spaced apart parallel electrodes disposed on the first plurality of electrodes and oriented orthogonal thereto, which electric fields are adapted to selectively change the index of refraction of the electrooptical material across a second dimension thereof to provide for a second predetermined index of refraction profile along the second dimension, and whereby the change in index of refraction across the second dimension is adapted to change the angle at which an optical beam entering the electrooptic lens exits the lens;

a first voltage source coupled to the first plurality of electrodes and the at least one ground electrode for applying predetermined voltages to the first plurality of electrodes to create the first predetermined index of refraction profile in the electrooptic material; and

a second voltage source coupled to the second plurality of electrodes and the at least one ground electrode for applying predetermined voltages to the second plurality of electrodes to create the second predetermined index of refraction profile in the electrooptic material.

13. The lens system of claim 12 wherein the electrooptic material comprises barium titanate (BaTiO₃).

14. The lens system of claim 12 wherein the electrooptic material comprises lithium niobate (LiNbO₃).

15. The lens system of claim 12 wherein the first and second voltage sources are adapted to provide electric fields in the range of 0 kV/centimeter to 100 kV/centimeter, respectively, to the first and second pluralities of positive electrodes.

16. The lens system of claim 12 wherein the first and second pluralities of electrodes and the at least one ground electrode are substantially transparent to the optical beam.

17. The lens system of claim 16 wherein the first and second pluralities of electrodes and the at least one ground electrode are disposed normal to the direction of propagation of an optical beam.