Optical Detection and Ranging Sensor System For Sense and Avoid, and Related Methods

• US 20110134249A1
• Filed: 12/04/2009
• Published: 06/09/2011
• Est. Priority Date: 12/04/2009
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Jones, Michael I., Wood, Rhande P.
• Granted Patent: US 8,400,511 B2
• Time in Patent Office: Days
• US Class Current: 348/164
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G05D 1/106 Change initiated in response to external conditions, e.g. avoidance of elevated terrain or of no-fly zones
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An apparatus carried by an unmanned vehicle to provide passive sensing and facilitate avoiding airborne aerial obstacles is provided. The apparatus can include at least one, but typically multiple optical systems installed, for example, in the nose of the aerial vehicle to passively sense and determine a range, direction, and velocity of the airborne obstacles to allow the aerial vehicle to avoid the airborne obstacles. The typical optical system includes at least one focal plane array or other imaging device configured to receive a wide field of view and at least one focal plane array or other imaging device configured to receive a steerable narrow field of view within the wide field of view to allow concentrated determination of the range, direction, and/or velocity of obstacles detected by the wide field of view imaging devices.

Claims

1. An object detection and avoidance apparatus carried by an unmanned aerial vehicle to provide passive sensing and facilitate avoiding airborne obstacles, the apparatus including at least one optical system comprising:

a collimator positioned to receive and collimate light waves defining an optical image of an aerial environment within a substantial portion of a field of regard defining a wide field of view and to align the light waves having differing wavelengths entering the collimator to reduce dispersion of separate color components thereof, the aerial environment including one or more airborne objects;

a plurality of light-sensing elements defining a focal plane array positioned to receive at least a portion of the optical image within the wide field of view to generate image data;

a scan mirror assembly positioned in optical communication with the collimator and in optical communication with the focal plane array to selectively direct light reflected from the one or more airborne objects to the focal plane array according to a narrow field of view, the narrow field of view comprising an image area of less than at least approximately 10 percent of an image area of the wide field of view; and

a spatial light modulator comprising a plurality of micro-mirrors, the spatial light modulator positioned in optical communication with the scan mirror assembly and the focal plane array and configured to adjust light intensity of light directed to the focal plane array responsive to environmental lighting conditions of the light received from the scan mirror assembly to thereby maintain the light intensity of the light directed to the focal plane array below a maximum intensity level.

2. The object detection and avoidance apparatus as defined in claim 1, wherein the spatial light modulator comprises an infrared spatial light modulator configured to adjust relative aperture size of light in an infrared spectrum received from the scan mirror assembly to rapidly optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the focal plane array to enhance determining atmospheric blur and object range estimates.

3. The object detection and avoidance apparatus as defined in claim 1, wherein the scan mirror assembly includes a first and a second scan mirror to provide airborne object selection according to a narrow field of view from within the wide field of view.

4. The object detection and avoidance apparatus as defined in claim 1, wherein the spatial light modulator is a first spatial light modulator configured for adaptive aperture and light intensity control, and wherein the optical system further comprises:

a second spatial light modulator comprising an array of liquid crystals, the second spatial light modulator positioned in optical communication with the first spatial light modulator and the focal plane array and configured to selectively block light surrounding a target image to thereby substantially eliminate background light transmission to the focal plane array to reduce effective image overlap.

5. The object detection and avoidance apparatus as defined in claim 1, wherein the focal plane array is a first focal plane array positioned to generate image data according to a narrow field of view, wherein the spatial light modulator is a first spatial light modulator, and wherein the optical system further comprises:

a second focal plane array positioned to generate image data according to the wide field of view;

a beam splitter positioned to simultaneously provide the optical image of the aerial environment according to the wide field of view to the scan mirror assembly and to the second focal plane array; and

a second spatial light modulator comprising a plurality of micro-mirrors, the second spatial light modulator positioned in optical communication with the beam splitter and the second focal plane array and configured to adjust relative aperture size of light directed to the second focal plane array to rapidly optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the second focal plane array responsive to environmental lighting conditions of the light received from the beam splitter to thereby maintain the light intensity of the light directed to the second focal plane array below a maximum intensity level.

6. The object detection and avoidance apparatus as defined in claim 1, wherein the focal plane array is a first focal plane array positioned to generate image data according to a narrow field of view, wherein the spatial light modulator is a first spatial light modulator, and wherein the optical system further comprises:

a second focal plane array positioned to generate image data according to the wide field of view;

a flip mirror positioned optically upstream of the scan mirror assembly to alternatingly provide a substantially unattenuated form of the optical image of the aerial environment according to the wide field of view to the scan mirror assembly and to the second focal plane array to thereby substantially reduce error due to excessive attenuation of the optical image; and

a second spatial light modulator comprising a plurality of micro-mirrors, the second spatial light modulator positioned in intermittent optical communication with the flip mirror and in optical communication with the second focal plane array and configured to adjust relative aperture size of light directed to the second focal plane array to rapidly optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the second focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the second focal plane array responsive to environmental lighting conditions of the light received from the flip mirror to thereby maintain the light intensity of the light directed to the second focal plane array below a maximum intensity level.

7. The object detection and avoidance apparatus as defined in claim 1, wherein the scan mirror assembly includes a first and a second scan mirror to provide airborne object selection according to a narrow field of view from within the wide field of view, the object detection and avoidance apparatus further comprising a sensor control and image processor configured:

to provide control signals to the scan mirror assembly to thereby direct the first and the second scan mirrors to pan in combination to provide a selected portion of the image area of the wide field of view according to the narrow field of view to the focal plane array;

to provide control signals to the focal plane array to provide image data generation for a plurality of pairs of images at different sensor plane distances according to the narrow field of view; and

to receive the image data generated from the focal plane array to separately determine a range value to each of the one or more airborne objects.

8. The object detection and avoidance apparatus as defined in claim 7, wherein the optical system further comprises:

a focal plane array enclosure containing the focal plane array;

a piezoelectric stepper control motor assembly connected to the focal plane array enclosure;

a focal plane array position controller in communication with the sensor control and image processor and in communication with the piezoelectric stepper control motor assembly to selectively position each separate image within each pair of images at a different offset position to provide a different blurred circle radius between images within each image pair to enhance determining the atmospheric blur and range estimates; and

a spatial light modulator controller in communication with the sensor control and image processor and in communication with each separate one of the plurality of micro-mirrors and configured to individually control each of the plurality of micro-mirrors to adjust the relative aperture size and light distribution of light received from the scan mirror assembly to rapidly optimize blur differential between each of the plurality of pairs of images and blur for at least one selected airborne object within each image on the focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust the light intensity of light directed to the focal plane array.

9. The object detection and avoidance apparatus as defined in claim 7, wherein the first and the second scan mirrors are positioned to pan along separate, spaced apart axes, and wherein the optical system further comprises:

a first scan mirror motivator to provide panning of the first scan mirror along a first pan axis;

a second scan mirror motivator to provide panning of the second scan mirror along a second pan axis;

a scan mirror controller in communication with the sensor control and image processor and in communication with the first and the second scan mirror motivators to control panning of the first and the second scan mirrors to thereby provide for the airborne object selection according to a narrow field of view from within the wide field of view.

10. The object detection and avoidance apparatus as defined in claim 1,

wherein the optical system is a first optical system;

wherein the field of regard is approximately plus or minus 15 degrees elevation with respect to the lateral axes of the aerial vehicle and approximately plus or minus 110 degrees azimuth with respect to a longitudinal axis of the aerial vehicle; and

wherein the object detection and avoiding apparatus further comprises;

a plurality of other optical systems being substantially identical to the first optical system and optically spaced apart from each other and from the first optical system, carried in a forward portion of the aerial vehicle, and collectively configured in combination with the first optical system and with each other to provide object detection throughout the field of regard according to the following standard;

an approximately 90 percent or more probability of detection at a minimum distance of approximately 10 kilometers from the aerial vehicle for each airborne obstacle having at least a 22.5 square meters cross-section within the field of regard when the aerial vehicle is airborne.

11. The object detection and avoidance apparatus as defined in claim 1,

wherein the scan mirror assembly is a first scan mirror assembly;

wherein the field of regard is approximately plus or minus 15 degrees elevation with respect to the lateral axes of the aerial vehicle and approximately plus or minus 110 degrees azimuth with respect to a longitudinal axis of the aerial vehicle;

wherein the at least one optical system is a single optical system providing object detection throughout the extent of the field of regard; and

wherein the single optical system includes a second scan mirror assembly positioned optically upstream of the collimator to scan the extent of the field of regard.

12. The object detection and avoidance apparatus as defined in claim 1, wherein the focal plane array is a first imaging device positioned to generate infrared image data according to the narrow field of view, and wherein the optical system further comprises:

a second imaging device comprising a low light television positioned to generate visible light image data according to the narrow field of view;

a digital light processor positioned in optical communication with the scan mirror assembly and the first focal plane array and configured to adjust relative aperture size of light received from the scan mirror assembly to rapidly optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the first focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the second imaging device responsive to environmental lighting conditions of light received from the scan mirror assembly to thereby maintain the light intensity of light directed to the second imaging device below a maximum intensity level; and

a dichroic filter positioned to reflect infrared light received from the scan mirror assembly to the spatial light modulator and to pass visible light received from the scan mirror assembly to the digital light processor.

13. The object detection and avoidance apparatus as defined in claim 12, wherein the optical system further comprises one or more of the following:

a spectral filter positioned in optical communication with the scan mirror assembly via the dichroic filter and in optical communication with the second imaging device to provide spectral filtering; and

a polarizer positioned in optical communication with the scan mirror assembly via the dichroic filter and in optical communication with the second imaging device to provide polarization filtering.

14. The object detection and avoidance apparatus as defined in claim 1,

wherein the collimator comprises a collimating mirror positioned in optical communication with a primary parabolic mirror having a center aperture extending therethrough.

15. An object detection and avoidance apparatus carried by an unmanned aerial vehicle to provide passive sensing and facilitate avoiding airborne obstacles, the apparatus including at least one optical system comprising:

a collimator positioned to receive and collimate light waves defining an optical image of an aerial environment within a substantial portion of a field of regard defining a wide field of view and to align the light waves having differing wavelengths entering the collimator to reduce dispersion of separate color components thereof, the aerial environment including one or more airborne objects;

a first plurality of light-sensing elements defining a first focal plane array positioned to receive at least a portion of the optical image within the wide field of view to generate image data according to a narrow field of view;

a scan mirror assembly positioned in optical communication with the collimator and in optical communication with the focal plane array to selectively direct light reflected from the one or more airborne objects to the focal plane array according to a narrow field of view, the narrow field of view comprising an image area of less than at least approximately 10 percent of an image area of the wide field of view, the scan mirror assembly including a first and a second scan mirror to provide airborne object selection according to a narrow field of view from within the wide field of view;

a first infrared spatial light modulator comprising a plurality of micro-mirrors and positioned in optical communication with the scan mirror assembly and the first focal plane array and configured to adjust relative aperture size of light received from the scan mirror assembly to optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the first focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the first focal plane array responsive to environmental lighting conditions of the light received from the scan mirror assembly to thereby maintain the light intensity of the light directed to the first focal plane array below a maximum intensity level;

a second plurality of light-sensing elements defining a second focal plane array positioned to receive the optical image within the wide field of view to generate image data according to the wide field of view;

a beam splitter positioned to simultaneously provide the optical image of the aerial environment according to the wide field of view to both the scan mirror assembly and to the second focal plane array; and

a second infrared spatial light modulator comprising a plurality of micro-mirrors, the second spatial light modulator positioned in optical communication with the beam splitter and the second focal plane array and configured to adjust relative aperture size of light directed to the second focal plane array to optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the second focal plane array to enhance determining atmospheric blur and range estimates, and to adjust light intensity of light directed to the second focal plane array responsive to environmental lighting conditions of the light received from the beam splitter to thereby maintain the light intensity of the light directed to the second focal plane array below a maximum intensity level.

16. The object detection and avoidance apparatus as defined in claim 15, further comprising a sensor control and image processor configured:

to provide control signals to the scan mirror assembly to thereby direct the first and the second scan mirrors to pan in combination to provide a selected portion of the image area of the wide field of view according to the narrow field of view to the focal plane array;

to provide control signals to the first focal plane array to provide image data generation for a plurality of pairs of images at different sensor plane distances according to the narrow field of view;

to receive the image data generated from the focal plane array to separately determine a range value to each of the one or more airborne objects;

to provide control signals to the second focal plane array to provide image data generation for a plurality of pairs of images at different sensor plane distances according to the wide field of view; and

to receive the image data generated from the focal plane array to separately determine a range value to each of the one or more airborne objects.

17. The object detection and avoidance apparatus as defined in claim 15, wherein the first and the second infrared spatial light modulators are configured for adaptive aperture and light intensity control, and wherein the optical system further comprises:

a first achromatic doublet positioned between the first spatial light modulator and the first focal plane array to correct residual transverse chromatic aberrations therebetween;

a second achromatic doublet positioned between the first spatial light modulator and the first achromatic doublet; and

a third spatial light modulator comprising an array of liquid crystals, the third spatial light modulator positioned in optical communication with the first infrared spatial light modulator and the first focal plane array and selectively positionable to selectively block light surrounding a target image to thereby substantially eliminate background light transmission to the first focal plane array to reduce effective image overlap.

18. The object detection and avoidance apparatus as defined in claim 15, wherein the optical system further comprises:

a third focal plane array comprising the electro-optical device positioned to generate visible light image data according to the narrow field of view;

a digital light processor positioned in optical communication with the scan mirror assembly and the third focal plane array and configured to adjust relative aperture size of light received from the scan mirror assembly to optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the third focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the third focal plane array responsive to environmental lighting conditions of light received from the scan mirror assembly to thereby maintain the light intensity of light directed to the third focal plane array below a maximum intensity level; and

a dichroic filter positioned to reflect the infrared portion of the light received from the scan mirror assembly to the first spatial light modulator and to pass the visible portion of the light received from the scan mirror assembly to the digital light processor.

19. The object detection and avoidance apparatus as defined in claim 18, wherein the optical system further comprises one or more of the following:

a spectral filter positioned in optical communication with the scan mirror assembly via the dichroic filter and in optical communication with the third focal plane array to provide spectral filtering; and

a polarizer positioned in optical communication with the scan mirror assembly via the dichroic filter and in optical communication with the third focal plane array to provide polarization filtering.

20. An object detection and avoidance apparatus carried by an unmanned aerial vehicle to provide passive sensing and facilitate avoiding airborne obstacles, the apparatus including at least one optical system comprising:

a collimator positioned to receive and collimate light waves defining an optical image of an aerial environment within a substantial portion of a field of regard defining a wide field of view and to align the light waves having differing wavelengths entering the collimator to reduce dispersion of separate color components thereof, the aerial environment including one or more airborne objects, the collimator comprising a collimating mirror positioned in optical communication with a primary parabolic mirror having a center aperture extending therethrough;

a plurality of light-sensing elements defining a focal plane array positioned to alternatingly receive the optical image within the wide field of view to generate image data according to the wide field of view to receive at least a portion of the optical image within the wide field of view to generate image data according to a narrow field of view;

a first spatial light modulator comprising a plurality of micro-mirrors and positioned in optical communication with the collimator and the focal plane array and configured to adjust relative aperture size of light received from the collimator to optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the focal plane array responsive to environmental lighting conditions of the light received from the collimator to thereby maintain the light intensity of the light directed to the focal plane array via a first optical pathway below a maximum intensity level;

a narrow field of view lens assembly comprising a first achromatic doublet and a biconcave lens positioned in combination between the first spatial light modulator and the focal plane array to provide the focal plane array at least a portion of the optical image within the wide field of view according to the narrow field of view;

a second spatial light modulator comprising a plurality of micro-mirrors, the second spatial light modulator positioned in optical communication with the collimator and the focal plane array to adjust relative aperture size of light directed to the focal plane array to optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the focal plane array responsive to environmental lighting conditions of the light received from the collimator to thereby maintain the light intensity of the light directed to the focal plane array via a second optical pathway below a maximum intensity level;

a second achromatic doublet positioned between the second spatial light modulator and the focal plane array to correct residual transverse chromatic aberrations therebetween;

a flip mirror positioned optically between the focal plane array and the first spatial light modulator along the first optical pathway, and positioned optically between the focal plane array and the second spatial light modulator along the second optical pathway to alternatingly provide a substantially unattenuated form of the optical image of the aerial environment according to the narrow field of view and provide a substantially unattenuated form of the optical image of the aerial environment according to the wide field of view to thereby provide for generating image data according to both the wide field of view and the narrow field of view using the same focal plane array; and

a beam pathway managing device comprising one or more of the following;

a beam splitter positioned to simultaneously provide the optical image of the aerial environment according to the wide field of view to both the first and the second spatial light modulators,

a half silvered mirror positioned to simultaneously provide the optical image of the aerial environment according to the wide field of view to both the first and the second spatial light modulators, and

a second flip mirror positioned to alternatingly provide the optical image of the aerial environment according to the wide field of view to the first and the second spatial light modulators; and

a scan mirror assembly comprising first and second scan mirrors positioned optically upstream of the collimator and in optical communication with the collimator to scan the entire extent of the field of regard to thereby selectively direct light reflected from the one or more airborne objects to the beam pathway managing device according to the wide field of view.

21. The object detection and avoidance apparatus as defined in claim 21, further comprising a sensor control and image processor configured:

to provide control signals to the scan mirror assembly to thereby direct the first and the second scan mirrors to pan in combination to provide a selected portion of a image area within the field of regard to the beam pathway managing device according to the wide field of view;

to provide control signals to the flip mirror to select between the first and the second optical pathways;

to provide control signals to the focal plane array to provide image data generation for a plurality of pairs of images at different sensor plane distances according to the narrow field of view and to provide image data generation for a plurality of pairs of images at different sensor plane distances according to the wide field of view; and

to receive the image data generated from the focal plane array to separately determine a range value to each of the one or more airborne objects.

22. An object detection and avoidance apparatus carried by an unmanned aerial vehicle to provide passive sensing and facilitate avoiding airborne obstacles, the apparatus including at least one optical system comprising:

a collimator positioned to receive and collimate light waves defining an optical image of an aerial environment within a substantial portion of a field of regard defining a wide field of view and to align the light waves having differing wavelengths entering the collimator to reduce dispersion of separate color components thereof, the aerial environment including one or more airborne objects;

a first plurality of light-sensing elements defining a first focal plane array positioned to receive the optical image within the wide field of view to generate image data according to a wide field of view;

a second plurality of light-sensing elements defining a second focal plane array positioned to receive the optical image within the wide field of view simultaneously with that of the first focal plane array and positioned to generate image data according to the wide field of view;

a beam pathway management device comprising a half silvered mirror positioned to simultaneously provide the optical image of the aerial environment according to the wide field of view to both the first focal plane array and the second focal plane array;

a first digital light processor positioned in optical communication with the beam pathway management device and the first focal plane array and positioned to adjust relative aperture size of light received from the beam pathway management device to optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the first focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the first focal plane array responsive to environmental lighting conditions of the light received from the beam pathway management device thereby maintain the light intensity of the light directed to the first focal plane array below a maximum intensity level;

a second digital light processor positioned in optical communication with the beam pathway management device and the second focal plane array to adjust relative aperture size of light directed to the second focal plane array to optimize blur differential between each of a plurality of pairs of images and blur for at least one selected airborne object within each image on the second focal plane array to enhance determining atmospheric blur and object range estimates, and to adjust light intensity of light directed to the second focal plane array responsive to environmental lighting conditions of the light received from the beam pathway management device to thereby maintain the light intensity of the light directed to the second focal plane array below the maximum intensity level;

an image gathering lens assembly positioned to gather incoming light from the aerial environment that is within the wide field of view; and

a scan mirror positioned optically upstream of the collimator and in optical communication with the collimator to scan the entire extent of the field of regard to thereby selectively direct light reflected from the one or more airborne objects to the beam pathway managing device according to the wide field of view.

23. The object detection and avoidance apparatus as defined in claim 22, further comprising a sensor control and image processor configured:

to provide control signals to the scan mirror to thereby direct the scan mirrors to pan to provide a selected portion of an image area of the field of regard to the collimator according to the wide field of view;

to provide control signals to the first focal plane array and to the second focal plane array to provide simultaneous image data generation of pairs of images according to the wide field of view to determine atmospheric blur and to generate a plurality of the pairs of images at different sensor plane distances according to the wide field of view to determine a range value to each of the one or more airborne objects; and

to receive the image data generated from the focal plane array to separately determine the range value to each of the one or more airborne objects.

24. A method of passively sensing and avoiding aerial targets, the method comprising the steps of:

collecting image data for each image of a pair of images of an aerial environment within a field of regard including one or more airborne objects, each image of the pair of images including an atmospheric blur component, the image data for each of the pair of images separately collected using at least one different optical parameter setting for an optical system having a field of view;

comparing the image data for one of the pair of images to the image data of the other of the pair of images responsive to the collected image data to determine an approximate amount of atmospheric blur in the image data;

determining the amount of atmospheric blur responsive to the comparison to thereby remove the atmospheric blur from image data for at least one of the pair of images to define conditioned image data; and

determining an approximate range to each of the one or more airborne objects within the field of view of the optical system responsive to the conditioned image data

25. The method as defined claim 24, wherein the one or more airborne objects is a plurality of airborne objects, and wherein the step of determining an approximate range to each of the one or more airborne objects within the field of view of the optical system includes the steps of:

removing the atmospheric blur from image data for at least one of the pair of images to generate the conditioned image data; and

forming a range map of the range of each separate one of the plurality of airborne objects using conditioned image data derived from two or three pairs of images of the environment within the field of view of the optical system.

26. The method as defined claim 24,

wherein the one or more airborne objects is a plurality of airborne objects, wherein the field of view is a wide field of view;

wherein the method further comprises the step of prioritizing the plurality of airborne objects within the wide field of view responsive to the respective determined approximate range;

wherein the optical system comprises a first portion configured to determine an approximate range of each of the plurality of airborne objects within the wide field of view of the optical system, and a second portion configured to determine an approximate range of each of the plurality of airborne objects within a narrow field of view of the optical system, the narrow field of view comprising an image area of less than at least approximately 10 percent of an image area of the wide field of view of the optical system; and

wherein the step of determining an approximate range to each of the one or more airborne objects within the field of view of the optical system includes the steps of;

determining an approximate range of each of the plurality of airborne objects within the wide field of view of the optical system,

determining one of the plurality of airborne objects located within the wide field of view of the first portion of the optical system to have a highest priority to define a highest priority airborne object,

positioning components of the second portion of the optical system so that the highest priority airborne object is within the narrow field of view of the second portion of the optical system, and

determining a first, a second, and a third approximate range to the highest priority airborne object.

27. The method as defined claim 26, further comprising the step of:

determining the approximate direction and velocity of the high-priority airborne object responsive to the determined first and second approximate ranges.

28. The method as defined claim 27, wherein the optical system includes a scan mirror assembly comprising a first and a second scan mirror configured to provide airborne object selection according to the narrow field of view from within the wide field of view, the method further comprising the step of:

projecting an anticipated location of the highest priority airborne object during a next range determination responsive to the determined third approximate range;

panning the first and a second scan mirrors to substantially position a center of the narrow field of view at approximately the anticipated location of the highest priority airborne object during the next range determination responsive to the projecting to enhance determining range, direction, and velocity of the highest priority airborne object; and

determining an enhanced value for the range, direction, and velocity of the high-priority airborne object responsive to the panning.

29. The method as defined claim 24,

wherein the one or more airborne objects is a plurality of airborne objects;

wherein the optical system includes a focal plane array and a scan mirror assembly in optical communication with the focal plane array to selectively direct light reflected from the plurality of airborne objects to the focal plane array; and

wherein the method further comprises the step of;

performing a rapid optimization of one or more of the following;

blur differential between a pair of images and blur for a selected airborne object within an image on the focal plane array to include the step of adjusting a relative aperture size of light received from the scan mirror assembly to enhance determining atmospheric blur and object range estimates for each of the plurality of airborne objects.

30. The method as defined claim 24, wherein the one or more airborne objects is a plurality of airborne objects, the method further comprising the steps of:

determining an approximate location, direction, and velocity of at least a highest-priority one of the plurality of airborne objects;

determining a trajectory to avoid each of the plurality of airborne objects by at least 500 feet; and

performing an evasive maneuver responsive to the determined trajectory to avoid each of the plurality of airborne objects by at least 500 feet.