Agile optical beam steering system

• US 4,823,402 A
• Filed: 04/21/1986
• Issued: 04/18/1989
• Est. Priority Date: 04/21/1986
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Corporation
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Brooks, Robert E.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Van Beek, Leslie
• Application Number:
  US06/853,836
• Time in Patent Office: 1,093 Days
• Field of Search: 455/604, 455/617, 455/619, 455/618, 455/606, 455/607, 356/4, 356/5, 356/1, 250/203 R, 358/104, 358/87, 358/206, 358/207, 358/231, 358/232, 358/233, 358/88, 358/208, 358/199, 350/6.1, 350/6.5, 350/6.6, 350/6.7, 350/6.9, 350/6.91
• US Class Current: 398/124
• CPC Class Codes: H04B 10/11 Arrangements specific to free-space transmission, i.e. transmission through air or vacuum

Abstract

A beam deflection system for use in optical radar, communications, or optical display apparatus, having the ability to scan multiple "target" clusters that are widely scattered over a large angular field. In its transmission mode of operation, the system switches a laser beam sequentially across an array of focal elements, moving the beam at high speed, since total beam movement across the array is limited to only a few degrees. The system includes an expansion telescope, which expands the succession of beams from the array of focal elements and directs them onto an array of larger, movable optical elements, such as gimbaled mirrors, which direct the successive beams toward scattered target areas in a large angular field. The system also includes a beam scanning device, for "microscanning" the beam through a number of separately resolvable positions within the field of view of each of the array of focal elements.

Claims

1. An optical beam deflection system, comprising:

first beam deflection means, for deflecting one or more optical beams rapidly through small increments to direct the beams successively to any subfields of view selected from a plurality of N subfields of view, where N is greater than the number of optical beams, and to point the beams as desired within each subfield of view; and

second beam deflection means having an equal plurality of N optical elements arrayed in the corresponding subfields of view to receive the beams from the first beam deflection means, wherein the angular positions of the optical elements are selected to direct the optical beams successively to desired target areas in a relatively large angular field of regard.

2. An optical beam deflection system as defined in claim 1, and further including:

a plurality of focusing elements, each individually controllable, for focusing the beams in the plurality of subfields.

3. An optical beam deflection system as defined in claim 2, and further comprising:

at least one beam expansion telescope located between the first and second beam deflection means.

4. An optical beam deflection system as defined in claim 3, wherein:

there are a plurality of beam expansion telescopes, one for each subfield of view.

5. An optical beam deflection system as defined in claim 1, wherein:

the optical elements in the second beam deflection means are steerable mirrors.

6. An optical beam deflection system as defined in claim 3, and further including:

a plurality of focusing elements, each individually controllable, for focusing the beams in the plurality of subfields.

7. An optical beam deflection system as defined in claim 6, and further comprising:

at least one beam expansion telescope located between the first and second beam deflection means.

8. An optical beam deflection system as defined in claim 7, wherein:

there are a plurality of beam expansion telescopes, one for each subfield of view.

9. An optical beam deflection system as defined in claim 5, and further comprising:

at least one beam expansion telescope located between the first and second beam deflection means.

10. An optical beam deflection system as defined in claim 9, wherein:

there are a plurality of beam expansion telescopes, one for each subfield of view.

11. An optical beam deflection system as defined in claim 1, and further comprising:

at least one beam expansion telescope located between the first and second beam deflection means.

12. An optical beam deflection system as defined in claim 11, wherein:

there are a plurality of beam expansion telescopes, one for each subfield of view.

13. An optical beam deflection system, comprising:

a high-speed beam-pointing mechanism, for switching an optical beam rapidly through a succession of preselected discrete angular positions, each position having associated with it a smaller angular field of view and separated form neighboring fields of view by relatively small angles;

an array of focusing elements located to receive the beam at each of the angular positions and to focus the beam for each field of view onto a focal surface;

an array of optical elements each positioned to receive a beam from one of the focusing elements, wherein the angular orientations of the optical elements are selected to direct the optical beam successively to desired target areas in a relatively large angular field of regard; and

beam telescope means disposed between the array of focusing elements and the array of optical elements.

14. An optical beam deflection system as defined in claim 13, wherein:

the beam telescope means is a single expansion telescope shared by all of the focusing elements.

15. An optical beam deflection system as defined in claim 13, wherein:

the optical elements are angularly steerable to track moving target positions in the field of regard.

16. An optical beam deflection system as defined in claim 13, wherein:

the system is used in conjunction with a beam transmitter; and

the beam transmitter is positioned to direct a light beam onto the high-speed scanning mechanism.

17. An optical beam deflection system as defined in claim 13, wherein:

the optical elements are steerable mirrors.

18. An optical beam receiver system, comprising:

an array of optical elements positioned to receive optical beams form target positions, each of which is located within one of a plurality of fields of view in a large angular field of regard, the optical elements being movable independently to track the target position, and oriented in such a manner as to deflect the optical beams from the plurality of fields of view along a group of closely spaced and more nearly parallel paths;

beam telescope means disposed in the more nearly parallel beam paths to focus the received beams;

optical detection means, for detecting the received beams emerging from the beam telescope means, and locating each target by the field of view with which it is associated and its position within the field of view; and

wherein the optical detection means includes an optical detector and a high-speed beam pointing device, for scanning the separate fields of view in turn with the optical detector.

19. An optical beam deflection system, comprising:

an array of focusing elements positioned to focus incident optical beams onto corresponding subfields of a focal surface;

first beam deflection means, for deflecting an optical beam rapidly through small increments to move the beam from one focusing element to another;

second beam deflection means having a plurality of steerable optical elements capable of movement through relatively large angles; and

optical means for directing an optical beam from each subfield of the focal surface onto a corresponding one of the plurality of steerable optical elements;

wherein the angular positions of the steerable optical elements are selected to direct an optical beam successively to desired target areas in a relatively large angular field.

20. An optical beam deflection system as defined in claim 19, wherein:

the first beam deflection means includes means for scanning a beam rapidly from one focusing element to another, and means for scanning the beam by much smaller angles within the field of view of each focusing element, to produce a corresponding scan of the field of view of each steerable optical element.

21. An optical beam deflection system as defined in claim 19, wherein:

the system is used in conjunction with a beam transmitter; and

the beam transmitter is positioned to direct a light beam onto the first beam deflection means.

22. An optical beam deflection system as defined in claim 19, wherein:

the system is used in conjunction with a beam transmitter; and

the beam transmitter is integrated into the first deflection means.

23. An optical beam deflection system as defined in claim 19, wherein:

the system is used in conjunction with an optical receiver; and

a received light beam from a selected target field of view in the large field of regard is transmitted to one or more of the steerable optical elements and thence through the optical means, one of the focusing elements, and the first beam scanning mechanism, to be received in the optical receiver.

24. An optical beam deflection system as defined in claim 19, wherein:

the array of focusing elements is a two-dimensional array of lenses.

25. An optical beam deflection system as defined in claim 24, wherein:

the optical means includes an expansion telescope mirror.

26. An optical beam deflection system as defined in claim 27, wherein:

the optical means includes an expansion telescope mirror.

27. An optical beam deflection system as defined in claim 19, wherein:

the array of focusing elements is a two-dimensional array of mirrors.

28. An optical radar system having the ability to rapidly scan multiple targets in a wide angular field of regard, the system comprising:

an optical transmitter providing a source optical laser beam;

a high-speed beam-scanning mechanism, for scanning the optical beam rapidly through a succession of preselected angular positions, each with a small angular field of view and separated by relatively small angles;

an array of focusing elements located to receive the beam at each of the angular positions and to focus a received beam onto subfields of a focal plane;

optical means for expanding the angular field of the optical beam and expanding the angular spacing between its successive positions;

an array of angularly movable optical elements each positioned to receive the expanded beam in its expanded successive angular positions, and deflecting the beam to one of a plurality of areas in a relatively large angular field of regard; and

an optical receiver, positioned to receive light reflected or transmitted from targets and transmitted via at least one of the movable optical elements, the optical means, at least one of the array of focusing elements, and the high-speed scanning mechanism.

29. An optical radar system as defined in claim 28, wherein:

the optical receiver includes a plurality of detector arrays for simultaneous monitoring of optical beams received from a plurality of targets in a plurality of fields of view.

30. An optical radar system as defined in claim 28, wherein the optical receiver includes:

a detector array for simultaneously monitoring optical beams received from a plurality of targets from an entire field of view; and

means for optically selecting which of the fields of view is directed to the detector array, to permit monitoring of optical beams recieved from a plurality of targets in a plurality of fields of view in an entire field of regard.

31. An optical radar system as defined in claim 28, wherein:

the beam scanning mechanism includes means for scanning the beam through a number of angular positions within the field of view of each of the focusing elements.

32. An optical radar system as defined in claim 31, wherein:

the angularly movable optical elements are steerable mirrors.

33. An optical communications system as defined in claim 28, wherein:

the beam scanning mechanism includes means for scanning the beam through a number of angular positions within the field of view of each of the focusing elements.

34. An optical communications system for communication with multiple transmitter/receivers that can be widely scattered across a large angular field of regard, the system comprising:

an optical transmitter providing a source optical laser beam;

a high-speed beam-scanning mechanism, for scanning the optical beam rapidly through a succession of preselected and relatively closely spaced beam positions, each with a small angular field of view;

an array of focusing elements located to receive the beam at each of the beam positions and to focus a received beam onto subfields of a focal plane;

optical means for expanding the optical beam;

an array of angularly movable optical elements each positioned to receive the expanded beam in its successive beam positions, and deflecting the beam to one of a plurality of areas in a relatively large angular field of regard; and

an optical receiver, positioned to receive light beams transmitted from targets via the movable optical elements, the optical means, and the array of focusing elements.

35. An optical communications system as defined in claim 34, wherein:

the angularly movable optical elements are steerable mirrors.

36. An optical communications system as defined in claim 35, and further including:

a second high-speed beam-scanning mechanism;

means for guiding received beams into the second beam-scanning mechanism, for deflection into the optical receiver.

37. An optical communications system as defined in claim 35, and further comprising:

a second high-speed beam-scanning mechanism;

a reflection grating providing a deflection angle dependent on the wavelength of the optical beam impinging on it, and positioned to discriminate between transmitted signals of different wavelengths received from the transmitter/receivers;

a second optical receiver operating at a different wavelength from the first optical receiver;

whereby the system is capable of simultaneously receiving signals for one purpose at the second optical receiver, and transmitting or receiving other signals at a different wavelength.

38. An optical communications system as defined in claim 37, and further comprising:

a second reflection grating disposed in the path of transmitted optical beams, to compensate for unwanted changes in wavelength of the transmitted beams; and

a third reflection grating disposed in the path of received optical beams, to compensate for unwanted changes in wavelength of the received beams.

39. An optical display system for producing multiple images over a relatively wide angular field, the system comprising:

an optical source for producing one or more optical beams;

a high-speed beam-switching mechanism, for switching the optical beams from the source rapidly from one to another of a succession of preselected and relatively closely spaced, discrete beam positions, each such beam position being associated with a separate subfield with a small angular field of view;

an array of independently adjustable focusing elements located to receive the beams at each of the beam positions and to focus the beams independently;

an array of angularly movable optical elements each positioned to receive the beams in their successive beam positions, and angularly oriented to deflect the beams to selected ones of a plurality of areas in a relatively large angular field of regard; and

a display screen positioned to receive the independently focused beams deflected from the movable optical elements, to produce a plurality of images at selected positions on the screen.

40. An optical display system as defined in claim 39, wherein:

the optical source includes a laser and all of the resultant images are produced by appropriately scanning the laser beam.

42. An optical display system as defined in claim 39, and further comprising:

at least one beam telescope located in the beam path to the array of angularly movable optical elements.

41. An optical display system as defined in claim 41, wherein:

the optical source includes video imaging apparatus, and the high-speed beam-switching mechanism switches a video image rapidly between the movable optical elements.

43. An optical beam receiver system, comprising:

an array of optical elements positioned to receive optical beams from target positions, each of which is located within one of a plurality of fields of view in a large angular field of regard, the optical elements being oriented in such a manner as to deflect the optical beams form the plurality of fields of view along a group of closely spaced and more nearly parallel paths;

beam telescope means disposed in the more nearly parallel beam paths to focus the received beams;

optical detection means, for detecting the received beams emerging form the beam telescope means, and locating each target by the field of view with which it is associated and its position within the field of view;

wherein the optical detection means includes a plurality of detector arrays, one array for each of the fields of view, and each detector array can simultaneously monitor received optical beams from an entire field of view, and the plurality of detector arrays can monitor the optical beams received from the entire field of regard.

44. An optical beam receiver system, comprising:

an array of optical elements positioned to receive optical beams form target positions, each of which is located within one of a plurality of fields of view in a large angular field of regard, the optical elements being oriented in such a manner as to deflect the optical beams form the plurality of fields of view along a group of closely spaced and more nearly parallel paths;

beam telescope means disposed in the more nearly parallel beam paths to focus the received beams;

optical detection means, for detecting the received beams emerging form the beam telescope means, and locating each target by the field of view with which it is associated and its position within the field of view;

wherein the optical detection means includes a detector array for simultaneously monitoring received optical beams from an entire field of view, and means for optically selecting which of the fields of view is directed to the detector array, to permit monitoring of the entire field of regard.

45. An optical beam deflection system, comprising:

a high-speed beam-pointing mechanism, for switching an optical beam rapidly through a succession of preselected angular positions, each position having associated with it a small angular field of view and separated from neighboring fields of view by relatively small angles;

an array of focusing elements located to receive the beam at each of the angular positions and to focus the beam for each field of view onto a focal surface;

an array of optical elements each positioned to receive a beam form one of the focusing elements, wherein the angular positions of the optical elements are selected to direct the optical beams successively to desired target areas in a relatively large angular field of regard; and

beam telescope means disposed between the array of focusing elements and the array of optical elements;

and wherein the beam telescope means includes a plurality of expansion telescopes, one disposed between each focusing element and each optical element.

46. An optical beam deflection system, comprising:

a high-speed beam-pointing mechanism, for switching an optical beam rapidly through a succession of preselected angular positions, each position having associated with it a small angular field of view and separated from neighboring fields of view by relatively small angles;

an array of focusing elements located to receive the beam at each of the angular positions and to focus the beam for each field of view onto a focal surface;

an array of optical elements each positioned to receive a beam from one of the focusing elements, wherein the angular positions of the optical elements are selected to direct the optical beams successively to desired target areas in a relatively large angular field of regard; and

beam telescope means disposed between the array of focusing elements and the array of optical elements;

and wherein the beam telescope means includes plurality of expansion telescopes, one disposed between each focusing element and each optical element;

and wherein the high-speed scanning mechanism includes means for pointing the beam to a plurality of selected positions within each filed of view, to permit scanning of multiple target positions within each filed of view.

47. An optical beam deflection system, comprising:

a high-speed beam-pointing mechanism, for switching an optical beam rapidly through a succession of preselected angular positions, each position having associated with it a small angular field of view and separated from neighboring fields of view by relatively small angles;

an array of focusing elements located to receive the beam at each of the angular positions and to focus the beam for each field of view onto a focal surface;

an array of optical elements each positioned to receive a beam from one of the focusing elements, wherein the angular positions of the optical elements are selected to direct the optical beams successively to desired target areas in a relatively large angular field of regard; and

beam telescope means disposed between the array of focusing elements and the array of optical elements;

and wherein the beam telescope means includes a plurality of expansion telescopes, one disposed between each focusing element and each optical element;

and wherein the array of focusing elements is a two-dimensional array of lenses.

48. An optical beam deflection system, comprising:

a high-speed beam-pointing mechanism, for switching an optical beam rapidly through a succession of preselected and relatively closely spaced beam positions, each position having associated with it a small angular field of view;

an array of focusing elements located to receive the beam at each of the beam positions and to focus the beam for each field of view onto a focal surface;

an array of optical elements each positioned to receive a beam form one of the focusing elements, wherein the angular positions of the optical elements are selected to direct the optical beams successively to desired target areas in a relatively large angular field of regard; and

beam telescope means associated with the array of focusing elements;

wherein the system is used in conjunction with an optical receiver, and a received light beam from a selected field of view in the large field of regard is transmitted to one or more of the optical elements and thence through the beam telescope means, one of the focusing elements, and the high-speed beam-pointing mechanism, to be received in the optical receiver.