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

• US 6,809,307 B2
• Filed: 09/28/2001
• Issued: 10/26/2004
• Est. Priority Date: 09/28/2001
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Trafton, Alvin F., Byren, Robert W.
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): Lee, Patrick J.
• Application Number:
  US09/965,764
• Publication Number:
  US 20030062468A1
• Time in Patent Office: 1,124 Days
• Field of Search: 356/521, 356/121, 356/451, 356/452, 250/216, 250/237.G, 250/237.R, 250/201.9, 359/244-245, 359/249
• US Class Current: 250/201.9
• 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 detecting aberration in a first beam of electromagnetic energy without amplification thereof and providing an error signal in response thereto;

second means responsive to said error signal for providing a conjugate correction signal;

third means responsive to said conjugate correction signal for providing a predistorted reference beam;

fourth means including an amplifier for amplifying said predistorted reference beam to provide an amplifier distorted reference beam; and

fifth means for conjugating said amplifier distorted reference beam to provide said correction signal to said amplifier whereby amplifier provides an output beam predistorted to correct for said aberration in said first beam.

2. The invention of claim 1 wherein said first beam is a return beam comprising a reflection of a beam.

3. The invention of claim 2 wherein said first means includes a target wavefront sensor.

4. The invention of claim 3 wherein said first means includes a telescope in alignment with said target wavefront sensor.

5. The invention of claim 4 wherein said first means includes an aperture sharing element between said telescope and said target wavefront sensor.

6. The invention of claim 5 wherein said first means further includes an optical phased array disposed between said aperture sharing element and said target wavefront sensor.

7. The invention of claim 5 further including means for correcting for noncommon path errors in said aperture sharing element.

8. The invention of claim 7 wherein said means for correcting for noncommon path errors in said aperture sharing element includes a pseudo-conjugator adapted to sample said beam output by said amplifier via said aperture sharing element.

9. The invention of claim 8 wherein said means for correcting for noncommon path errors in said aperture sharing element further includes a local loop wavefront sensor adapted to receive a beam retro-reflected by said pseudo-conjugator and provide an error signal in response thereto.

10. The invention of claim 7 wherein said means for correcting for noncommon path errors in said aperture sharing element includes a Grating Rhomb adapted to sample said beam output by said amplifier.

11. The invention of claim 10 wherein said means for correcting for noncommon path errors in said aperture sharing element further includes a second wavefront error sensor for detecting aberration in said output beam.

12. The invention of claim 11 wherein said means for correcting for noncommon path errors in said aperture sharing element further includes a third wavefront error sensor for detecting aberration in said output beam due to said aperture sharing element.

13. The invention of claim 5 wherein said aperture sharing element is an output coupler or outcoupler.

14. The invention of claim 13 further including means for sensing aberrations in said predistorted reference beam due to said aperture sharing element.

15. The invention of claim 1 wherein said second means includes an adaptive optics processor.

16. The invention of claim 1 wherein said third means includes a master oscillator and an optical phased array.

17. The invention of claim 1 wherein said fifth means includes a phase conjugate mirror.

18. The invention of claim 17 wherein said second means includes a second phase conjugate mirror.

19. A method for controlling a beam including the steps of:

detecting aberration in a first beam of electromagnetic energy without amplification thereof and providing an error signal in response thereto;

providing a conjugate correction signal in response to said error signal;

providing a predistorted reference beam in response to said conjugate correction signal;

amplifying said predistorted reference beam to provide an amplifier distorted reference beam; and

conjugating said amplifier distorted reference beam to provide said correction signal to said amplifier whereby amplifier provides an output beam predistorted to correct for said aberration in said first beam.