System and method for effecting high-power beam control with adaptive optics in low power beam path

• US 20030062468A1
• Filed: 09/28/2001
• Published: 04/03/2003
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Byren, Robert W., Trafton, Alvin F.
• Granted Patent: US 6,809,307 B2
• Time in Patent Office: Days
• US Class Current: 250/216
• CPC Class Codes: F41H 13/0043 Directed energy weapons, i.e. devices that direct a beam of high energy content toward a target for incapacitating or destroying the target
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 27/0037 with diffracting elements G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876
• CPC Class Codes: G02B 27/4233 having a diffractive element [DOE] contributing to a non-imaging application diffusers having a diffractive element G02B5/0252; filters having a diffractive element G02B5/203; systems for controlling the direction of light having diffractive elements G02B26/0808; scanning systems having diffractive elements G02B26/106; beam shaping systems using diffractive optical elements G02B27/0944; beam splitting or combining systems operating by diffraction G02B27/1086

Abstract

A beam control system and method which utilizes the wavefront reversal property of nonlinear optical phase conjugation to permit incorporation of a liquid crystal OPA within the low power legs of the beam control system, thereby affording the advantages of the OPA without the power limitations thereof. The invention is adapted for use with a beacon for illuminating a target with a first beam of electromagnetic energy. The system includes a telescope (1010) for receiving a target return comprising a reflection of the first beam from the target. An optical phased array (1050) is included for correcting for aberrations in the wavefront of the target return. A mechanism is included for ascertaining the correction applied by the optical phased array to the target return. The mechanism applies the correction to a third beam which ultimately is the output beam. In the illustrative embodiment, the first beam of electromagnetic energy is optical energy and the mechanism includes a first phase conjugate mirror (1091) adapted to conjugate electromagnetic energy output by the third mechanism and a second phase conjugate mirror (1092) adapted to conjugate the output of the first phase conjugate mirror. The fourth mechanism further includes an amplifier (1088) for boosting the signal output by the second phase conjugate mirror (1092) to provide the output beam.

Claims

1. A beam control system comprising:

first means for receiving a first beam of electromagnetic energy;

second means for detecting aberrations in the first beam;

third means responsive to the second means for generating a second beam that is at least partially compensated with respect to the aberrations; and

fourth means for amplifying the second beam to provide an output beam.

2. The invention of claim 1 wherein the electromagnetic energy is optical energy.

3. The invention of claim 2 wherein the first means is a telescope.

4. The invention of claim 3 wherein the first beam is a reflection from a target.

5. The invention of claim 1 wherein the second means includes a wavefront error sensor.

6. The invention of claim 5 wherein the third means includes a processor responsive to the wavefront error sensor for providing a correction signal.

7. The invention of claim 6 wherein the third means further includes an optical phased array responsive to the correction signal.

8. The invention of claim 7 wherein the third means includes means for illuminating the phased array with a reference beam.

9. The invention of claim 8 wherein the third means includes a first conjugator disposed in the optical path of the reference beam and the phased array.

10. The invention of claim 9 wherein the third means further includes a second conjugator disposed in the optical path of the reference beam, the phased array and the first conjugator.

11. The invention of claim 10 wherein the fourth means includes an amplifier disposed in the optical path of the second conjugator.

12. The invention of claim 11 wherein the first and second conjugators are phase conjugate mirrors.

13. The invention of claim 9 wherein the third means includes a Grating-Rhomb disposed in the optical path of the first beam and the second beam.

14. The invention of claim 13 further including means for detecting aberrations in a wavefront of the output beam and providing a signal to the processor in response thereto.

15. The invention of claim 14 further including an aperture sharing element disposed in the optical path of the first and the second beams.

16. The invention of claim 15 further including means for detecting aberrations in the aperture sharing element and providing a signal to the processor in response thereto.

17. A beam control system adapted for use with a system for illuminating a target with a first beam of electromagnetic energy comprising:

first means for receiving a target return comprising a reflection of the first beam from the target;

second means for correcting for aberrations in the wavefront of the target return;

third means for ascertaining the correction applied by the second means to the target return; and

fourth means for applying the correction to a third beam, the third beam being an output beam.

18. The invention of claim 17 wherein the fourth means includes a first phase conjugate mirror adapted to conjugate electromagnetic energy output by the third means.

19. The invention of claim 18 wherein the fourth means further includes a second phase conjugate mirror adapted to conjugate the output of the first phase conjugate mirror.

20. The invention of claim 19 wherein the fourth means further includes means for amplifying an electromagnetic signal output by the second phase conjugate mirror.

21. The invention of claim 20 wherein the signal output by the means for amplifying is the output beam.

22. The invention of claim 17 wherein the second means is an optical phased array.

23. The invention of claim 22 further including an outcoupling element disposed between the first means and the second means.

24. The invention of claim 23 wherein the third means is a master oscillator adapted to provide a reference beam.

25. The invention of claim 24 wherein the reference beam illuminates the optical phased array and provides a wavefront error correction detection signal in response thereto.

26. The invention of claim 25 wherein the wavefront error correction detection signal illuminates a back surface of the outcoupling element and provides an outcoupling element back surface read signal in response thereto.

27. The invention of claim 26 further including a first phase conjugate mirror for conjugating the outcoupling element back surface read signal.

28. The invention of claim 27 wherein the conjugated outcoupling element back surface read signal is transmitted through the outcoupling element to a second phase conjugate mirror.

29. The invention of claim 28 wherein the second phase conjugate mirror conjugates the conjugated outcoupling element back surface read signal and provides the outcoupling element back surface read signal in response thereto.

30. The invention of claim 29 further including means for amplifying the outcoupling element back surface read signal.

31. The invention of claim 30 wherein the amplified outcoupling element back surface read signal is reflected off of the outcoupling element to provide the output beam.

32. The invention of claim 31 wherein the outcoupling element is an aperture sharing element.

33. The invention of claim 22 further including a wavefront error sensor adapted to receive a signal output by the optical phased array and provide a wavefront error signal in response thereto.

34. The invention of claim 33 further including a processor responsive to the wavefront error signal for providing a correction signal to the optical phased array.

35. The invention of claim 17 wherein the first beam of electromagnetic energy is optical energy.

36. The invention of claim 17 wherein the first means includes a telescope.

37. A high-energy laser comprising:

a telescope;

an aperture sharing element disposed in optical alignment with the telescope;

an optical phased array disposed an optical alignment with the aperture sharing element;

a wavefront error sensor disposed in optical alignment with the optical phased array and adapted to provide a wavefront error signal in response thereto;

a processor adapted to provide a correction signal to the optical phased array in response to the wavefront error signal;

a source of a reference beam disposed in optical alignment with the optical phased array and the aperture sharing element;

a first phase conjugate mirror disposed in optical alignment with the the reference beam;

a second phase conjugate mirror disposed in optical alignment with the first phase conjugate mirror; and

an optical amplifier disposed in optical alignment with the second phase conjugate mirror and the telescope.

38. A beam control method comprising the steps of:

illuminating a target with a first beam of electromagnetic energy;

receiving a target return comprising a reflection of the first beam from the target;

correcting for aberrations in the wavefront of the target return;

ascertaining the correction applied by the second means to the target return; and

applying the correction to a third beam, the third beam being an output beam.