Dual field of view sensor

• US 4,574,197 A
• Filed: 03/24/1983
• Issued: 03/04/1986
• Est. Priority Date: 03/24/1983
• Status: Expired due to Term

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Kliever, Waldo W.
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Fields, Carolyn E.
• Application Number:
  US06/478,438
• Time in Patent Office: 1,076 Days
• Field of Search: 250/334, 250/347, 250/332, 350/6.8, 350/274, 350/6.7, 358/206, 358/113, 358/88, 358/109
• US Class Current: 250/334
• CPC Class Codes: G02B 23/12 with means for image conversion or intensification
• CPC Class Codes: H04N 13/161 Encoding, multiplexing or demultiplexing different image signal components for multi-view video sequence encoding H04N19/597
• CPC Class Codes: H04N 13/218 using spatial multiplexing
• CPC Class Codes: H04N 13/341 using temporal multiplexing
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof
• CPC Class Codes: H04N 3/08 having a moving reflector

Abstract

A dual field of view sensor, particularly adapted for use as a forward-looking infrared night vision detector, includes a single detector (24) for receiving a light signal and developing an output electrical signal therefrom. A rotating polygon scanner (16) having a plurality of reflective facet (14) thereon receives light (12, 34) from two separate optical systems (10, 32) and directs the light onto the facets (14) of the scanner (16) at positions offset by one-half the facet angle such that the light beams alternately strike a facet and the juncture between two facets. The reflected light is then directed through a beam splitter 40 onto the detector in an alternating, interleaved sweeping motion. The beam splitter permits only one at a time of the light (12, 34) from entering the detector. In one embodiment, both optical systems include a steerable dual field of view telescope. In a second embodiment, a transparent display (60) such as an LCD panel, impresses a data image on one light beam (52) and the signals developed from that and another light beam are combined to drive a display. In a third embodiment, the two light beams represent the input to a stereoscopic viewing system, and the separate signals developed therefrom are used to drive a pair of small helmet-mounted displays for individual viewing by the wearer'"'"'s left and right eyes to provide stereoscopic night vision viewing.

Claims

1. A dual path optical sensor system comprising:

(a) detector means having an input and an output for receiving a light signal at said input and for converting the light signal into an electrical signal for transmission thereof from said output;

(b) a rotatable polygon scanner having a plurality of substantially equal reflective facets thereon;

(c) means for rotating said scanner at a constant speed;

(d) first optical means for receiving a first light beam and for directing the first light beam on said facets;

(e) second optical means for receiving the first light beam as it is reflected from said facets and for directing the first light beam onto said input of said detector means;

(f) third optical means for receiving a second light beam and for directing the second light beam onto said facets, said first and third optical means being mutually positioned so that, when the first light beam is impinging directly on one of said facets, the second light beam is impinging on the mid-point between two adjacent other ones of said facets, and vice-versa;

(g) fourth optical means for receiving the second light beam as it is reflected from said facets and for directing the second light beam onto said input of said detector means;

(h) means for preventing simultaneous receipt of the first and second light beams on said detector means input; and

(i) means connected to said output of said detector means for receiving and processing signals resulting from the first and second light beams.

2. The sensor system of claim 1 in which said preventing means comprises beam splitter means disposed in the paths of the first and second light beams for passing ones of the light beams that are being reflected from one of said facets and for blocking ones of the light beams that are impinging on the junction between two adjacent ones of said facets.

3. The sensor system of claim 1 wherein:

(a) said first and second optical means include independent controllable inlet means for selecting the direction of field of view for receiving an incoming light beam whereby two different fields of view can be selected simultaneously; and

(b) said signal receiving and processing means includes a pair of displays for viewing and means for directing the signal resulting from the first light beam to drive one of said displays and the signal resulting from the second light beam to drive the other of said displays.

4. The sensor system of claim 1 additionally comprising display means disposed in the path of the second light beam for receiving an electrical sighal at an input thereof and for impressing an optical representation of the light signal onto the second light beam to include the information in the electrical signal in the display image created by said signal receiving and processing means.

5. In a forward-looking infrared optical scanning system employing a detector, a signal processor, a rotating polygon scanner having reflective facets on its periphery, and a first optical assembly in which light entering from a first line of sight is directed against the rotating polygon scanner so that it is reflected from the facets sequentially across the detector in a sweeping scan pattern to produce a signal therefrom, the improvement comprising:

a second optical assembly having means for directing light entering from a second line of sight at a rotational angle against the reflective surface of the scanner at an angle which is out of phase by a one-half facet angle of rotation from that reflecting the light entering from the first line of sight to interleavedly sweep the light across the detector and thereby to enable the detector and signal process to be time-shared.

6. The improvement of claim 5 additionally comprising means for producing a combined image on a single display from the signal output from the detector derived from the light from said first and second lines of sight.

7. The improvement of claim 5 additionally comprising:

(a) a pair of displays; and

(b) means for processing the signal outputs from the detector derived from the light from the first and second lines of sight and for displaying them on respective ones of the displays.

8. The improvement of claim 7 wherein:

said first optical assembly and said second optical assemby respectively include directional telescope wide field of view and narrow field of view assemblies.

9. The improvement of claim 5 additionally comprising beam splitter means disposed in the paths of the light from the first and second lines of sight respectively for passing ones of the beams that are being reflected from one of said facets and for blocking ones of said light beams that are impinging on the junction between two adjacent ones of said facets.

10. A dual path optical sensor system comprising:

(a) an electro-optical sensor having an input surface for receiving impinging light and an output at which an electrical signal is produced as a function of light impinging on said input surface;

(b) a first optical system disposed to receive light from a first line of sight and to direct it along a first path;

(c) a second optical system disposed to receive light from a second line of sight and direct it along a second path;

(d) a rotating polygon scanner disposed to intercept and reflect the light in said first and second paths at a one-half facet angle offset between said first and second paths and to interleavedly sweep the light from said first and second paths towards said input surface; and

(e) means positioned between said sensor and said scanner for permitting only seriatim reception of the light from said first and second optical systems.

11. The optical sensor system of claim 10 additionally comprising means for producing a combined image from the signal output from said sensor as a result of the light from said first and second lines of sight on a single imager.

12. The optical sensor system of claim 10 additionally comprising:

(a) a pair of displays; and

(b) means for processing the signal outputs from said sensor as a result of the light from said first and second lines of sight and for displaying them on respective ones of the displays.

13. The optical sensor system of claim 10 wherein:

said first optical system and said second optical system both include directional telescope assemblies having different fields of view.

14. The optical system of claim 10 in which said means positioned between said sensor and said scanner comprises a beam chopper which passes light in a first of said beams that is being reflected from one of said facets and which blocks light in a second of said beams that is impinging on the junction between two adjacent ones of said facets.

15. A dual path forward-looking infrared sensor system comprising:

(a) a cryogenically-cooled electro-optical sensor having an input for receiving impinging light and an output at which an electrical signal is produced as a function of the impinging light;

(b) a first optical system disposed to receive light from a first line of sight, direct it along a first path, and focus it on said input;

(c) a second optical system disposed to receive light from a second line of sight, direct it along a second path, and focus it on said input;

(d) a rotating polygon scanner disposed to intercept and reflect the light in said first and second paths and having means defining a one-half facet angle offset between said first and second paths for sweeping the light from said first and second paths alternatingly across said input; and

(e) means positioned between said sensor input and said scanner for enabling only one at a time of the alternatingly swept light to be received by said sensor input.

16. The dual path forward-looking infrared sensor system of claim 15 additionally comprising means coupled to said sensor for producing a combined image from the sensor signal output.

17. The dual path forward-looking infrared sensor system of claim 15 additionally comprising:

(a) a pair of displays; and

(b) means coupled to said sensor for processing the signals output therefrom and for displaying the processed signals on respective ones of the displays.

18. The dual path forward-looking infrared sensor system of claim 15 wherein said first and second optical systems respectively have means which include directional telescope assemblies for changing the lines of sight of light entering said respective assemblies.

19. The dual path forward-looking infrared system of claim 15 in which said scanner includes a plurality of facets having junctions therebetween and said means positioned between said sensor input and said scanner comprises beam chopper means respectively passing the light reflected from one of said facets and blocking the light impinging on the junction between adjacent ones of said facets.