DUAL-FIELD-OF-VIEW OPTICAL SYSTEM

• US 20170126986A1
• Filed: 10/30/2015
• Published: 05/04/2017
• Est. Priority Date: 10/30/2015
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Belote, Brent, Robarge, James, Noethen, Mark
• Granted Patent: US 9,762,812 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 27/1066 for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/58 Means for changing the camera field of view without moving the camera body, e.g. nutating or panning of optics or image sensors
• CPC Class Codes: H04N 23/60 Control of cameras or camera modules
• CPC Class Codes: H04N 23/69 Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 5/265 Mixing

Abstract

A dual-field-of-view (FOV) optical imaging system having a primary FOV and a simultaneously viewable secondary FOV. One example of the system includes an imaging sensor, primary and secondary FOV objective optics configured to receive and output electromagnetic radiation corresponding to the primary FOV and secondary FOV, respectively, imager optics, and a field-of-view selection mechanism disposed between the secondary FOV objective optics and the imager optics and configured to selectively pass the second FOV to the imager optics, the imaging sensor being configured to produce primary FOV image frames and combined image frames that include imagery from both the primary and secondary fields-of-view.

Claims

1. A dual-field-of-view optical imaging system having a primary field-of-view and a secondary field-of-view and comprising:

a detector assembly including an imaging sensor;

primary field-of-view objective optics configured to receive first electromagnetic radiation from a scene and to output the first electromagnetic radiation corresponding to the primary field-of-view of the system;

secondary field-of-view objective optics configured to receive second electromagnetic radiation from the scene and to output the second electromagnetic radiation corresponding to the secondary field-of-view of the system;

imager optics configured to receive and focus the first electromagnetic radiation onto the imaging sensor, the imaging sensor being configured to produce primary field-of-view image frames from the first electromagnetic radiation; and

a field-of-view selection mechanism disposed between the secondary field-of-view objective optics and the imager optics and configured to selectively pass the second electromagnetic radiation to the imager optics, the imager optics being further configured to focus the second electromagnetic radiation onto the imaging sensor, and the imaging sensor being further configured to produce combined image frames from the first electromagnetic radiation and the second electromagnetic radiation together, the combined image frames including imagery from both the primary and secondary fields-of-view.

2. The dual-field-of-view optical imaging system of claim 1 wherein the field-of-view selection mechanism includes a shutter at least a portion of which is selectively movable into an optical path between the secondary field-of-view objective optics and the imager optics to block the second electromagnetic radiation from the imager optics, and selectively movable out of the optical path to pass the second electromagnetic radiation to the imager optics.

3. The dual-field-of-view optical imaging system of claim 2 wherein the field-of-view selection mechanism includes a rotating shutter wheel having a transmissive portion that passes the second electromagnetic radiation and a blocking portion that blocks the second electromagnetic radiation.

4. The dual-field-of-view optical imaging system of claim 1 wherein the field-of-view selection mechanism includes:

a beamsplitter disposed between the imager optics and both the primary and secondary field-of-view objective optics; and

a shutter positioned between the secondary field-of-view objective optics and the beamsplitter, the shutter having an open state in which the second electromagnetic radiation is directed to the beamsplitter and a closed state in which the second electromagnetic radiation is blocked from reaching the beamsplitter.

5. The dual-field-of-view optical imaging system of claim 4 wherein, when the shutter is in the closed state, the beamsplitter is configured to transmit a first portion of the first electromagnetic radiation to the imager optics and to reflect a second portion of the first electromagnetic radiation;

and

wherein, when the shutter is in the closed state, the beamsplitter is configured to receive and combine the first and second electromagnetic radiation, to transmit the first portion of the first electromagnetic radiation to the imager optics and to reflect the second portion of the first electromagnetic radiation, and to transmit a first portion of the second electromagnetic radiation to the imager optics and reflect a second portion of the second electromagnetic radiation with the second portion of the first electromagnetic radiation.

6. The dual-field-of-view optical imaging system of claim 1 further comprising image processing circuitry coupled to the imaging sensor and configured to receive and process the primary field-of-view image frames and the combined image frames from the imaging sensor, and to output first display images produced from the primary field-of-view image frames and corresponding to the primary field-of-view, and second display images produced from a combination of the primary field-of-view image frames and the combined image frames and corresponding approximately to the secondary field-of-view.

7. The dual-field-of-view optical imaging system of claim 6 wherein the imaging processing circuitry includes a frame buffer configured to store the primary field-of-view image frames sequentially one-by-one.

8. The dual-field-of-view optical imaging system of claim 7 wherein the image processing circuitry includes an image reconstruction module coupled to the frame buffer and configured, for each combined image frame, to:

receive the combined image frame;

receive a prior stored primary field-of-view image frame from the frame buffer;

compare the combined image frame with the stored primary field-of-view image frame to determine a content delta between the combined image frame and the stored primary field-of-view image frame; and

produce an approximate secondary field-of-view image frame based on the content delta.

9. The dual-field-of-view optical imaging system of claim 8 wherein the image processing circuitry is configured to process the approximately secondary field-of-view images to produce the second display images.

10. A method of simultaneously viewing two fields-of-view in an optical imaging system, the method comprising:

collecting, over a primary field-of-view, first electromagnetic radiation energy at an imaging sensor and producing therefrom a plurality of primary image frames;

simultaneously collecting, over a secondary field-of-view, second electromagnetic radiation energy using secondary objective optics;

selectively directing the second electromagnetic radiation energy to the imaging sensor;

at the imaging sensor, producing a plurality of combined image frames from a combination of the first electromagnetic radiation energy and the second electromagnetic radiation energy;

processing the plurality of primary image frames and the plurality of combined image frames to produce a first display image stream corresponding to the primary field-of-view and a second display image stream corresponding approximately to the secondary field-of-view; and

displaying the first and second display image streams.

11. The method of claim 10 wherein selectively directing the second electromagnetic radiation to the imaging sensor includes selectively moving a shutter into an optical path between the secondary objective optics and the imaging sensor to block the second electromagnetic radiation energy from reaching the imaging sensor, and selectively moving the shutter out of the optical path to allow the second electromagnetic radiation energy to reach the imaging sensor.

12. The method of claim 10 wherein processing the plurality of primary image frames and the plurality of combined image frames includes sequentially storing each one of the plurality of primary image frames in a frame buffer.

13. The method of claim 10 wherein processing the plurality of primary image frames and the plurality of combined image frames further includes producing a plurality of secondary image frames by, for each combined image frame of the plurality of combined image frames:

receiving the combined image frame at an image reconstruction module;

receiving a prior stored primary image frame at the image reconstruction module from the frame buffer; and

with the image reconstruction module, comparing the combined image frame and the prior stored primary image frame and subtracting imagery in the prior stored primary image frame from imagery in the combined image frame to produce a secondary image frame that corresponds approximately to the secondary field-of-view.

14. The method of claim 13 wherein producing the second display image stream includes processing the plurality of secondary image frames.

15. The method of claim 10 further comprising dynamically adjusting a saturation threshold of the imaging sensor.