Beam steering optical arrangement using Risley prisms with surface contours for aberration correction

• US 6,344,937 B1
• Filed: 03/03/1999
• Issued: 02/05/2002
• Est. Priority Date: 03/03/1999
• Status: Expired due to Fees

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Paiva, Richard A., Arndt, Thomas D., Ellis, Kenneth S., Knapp, David J., Mills, James P., Sparrold, Scott W.
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Treas, Jared
• Application Number:
  US09/262,157
• Time in Patent Office: 1,070 Days
• Field of Search: 359/720, 359/737, 359/831, 359/837, 359/669, 359/678, 359/208, 359/209, 359/210, 359/211, 359/557, 244/3.13, 244/3.16
• US Class Current: 359/837
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration

Abstract

A steerable optical arrangement. The inventive arrangement includes a first prism mounted for rotation about an optical axis and a second prism mounted for rotation about the optical axis. In accordance with the inventive teachings, the first prism and/or the second prism have at least one surface contoured to correct for optical aberration. In the illustrative embodiment, the first and second prisms are Risley prisms. In addition, the illustrative implementation includes a first motor arrangement for rotating the first prism about the optical axis and a second motor arrangement for rotating the second prism about the optical axis. A controller is provided for activating the first and second motors to steer the beam at an angle φ and nod the beam at an angle θ. At least two surfaces at least one prism is contoured to correct for astigmatism, coma, trefoil and other non-rotationally symmetric aberration. The contour is effected by laser etching, micro-machining or optical thin-film coating of the prisms in the manner disclosed herein.

Claims

1. A steerable optical arrangement, the optical arrangement comprising:

a first prism mounted for rotation about an optical axis and a second prism mounted for rotation about said optical axis, said first prism and/or said second prism having at least one surface contoured to correct for optical aberration.

2. The invention of claim 1 including first means for rotating said first prism about said optical axis.

3. The invention of claim 2 further including second means for rotating said second prism about said optical axis.

4. The invention of claim 3 further including means for controlling said first means and said second means to steer a beam at an angel φ

.

5. The invention of claim 4 further including means for controlling said first means and said second means to nod said beam at an angle θ

.

6. The invention of claim 1 wherein said first prism is a Risley prism.

7. The invention of claim 6 wherein said second prism is a Risley prism.

8. The invention of claim 1 wherein said optical aberration is astigmatism.

9. The invention of claim 1 wherein said optical aberration is coma.

10. The invention of claim 1 wherein said optical aberration is trefoil.

11. The invention of claim 1 wherein said optical aberration is any non-rotationally symmetric aberration.

12. The invention of claim 1 wherein said optical aberration is focus.

13. The invention of claim 1 wherein said optical aberration is astigmatism.

14. The invention of claim 1 wherein said optical aberration is coma.

15. The invention of claim 1 wherein said optical aberration is trefoil.

16. The invention of claim 1 including means for controlling the rotation of said first prism relative to said second prism.

17. The invention of claim 16 wherein said means for controlling includes means for rotating said first prism.

18. The invention of claim 17 wherein said means for controlling includes means for rotating said second prism.

19. A method for steering and correcting an optical line of sight including the steps of;

mounting a first prism for rotation about an optical axis and

mounting a second prism for rotation about said optical axis, said first prism and/or said second prism having at least one surface contoured to correct for optical aberration.

20. The invention of claim 19 including the step of rotating said first prism about said optical axis and rotating said second prism about said optical axis to steer said line of sight at an angle φ

and to nod said line of sight at an angle θ

.

21. The invention of claim 20 wherein said optical aberration is focus.

22. The invention of claim 19 wherein said first prism is a Risley prism.

23. The invention of claim 22 wherein said second prism is a Risley prism.

24. The invention of claim 19 wherein said optical aberration is astigmatism.

25. The invention of claim 19 wherein said optical aberration is coma.

26. The invention of claim 19 wherein said optical aberration is trefoil.