Seeker having scanning-snapshot FPA
View Patent ↗A dual-mode laser-based and image-based seeker for projectiles, missiles, and other ordnance that persecute targets by detecting and tracking energy scattered from targets. The disclosed embodiments use a single digital imager having a single focal plane array (FPA) sensor to sense data in both the image-based and laser-based modes of operation. A control mechanism controls pixel scanning at a sub-window of the FPA to tightly control the imager's shuttering to detect, decode and localize in the imager's field-of-view a known pulse repetition frequency (PRF) from a known designator in the presence of ambient light and other confusing target designators, each having a different PRF.
1. An imager comprising;
a focal plane array (FPA); and
an optical system communicatively coupled to the FPA, wherein said optical system is configured to perform a method comprising:
focusing laser energy comprising a first field-of-view to a first sub-window of said FPA;
focusing images comprising a second field-of-view identical to said first field-of-view to a second sub-window of said FPA;
pixel scanning said first sub-window of said FPA at an exposure rate that matches a predetermined pulse repetition frequency (PRF) to thereby decode laser energy focused by said optical system to said first sub-window at said predetermined PRF;
snapshot exposing said second sub-window of said FPA, thereby capturing image energy focused by said optical system to said second sub-window.
2. The imager of claim 1 , wherein the method performed by said optical system further comprises using said decoded laser energy to derive control information capable of being used to steer an ordinance to a target.
3. The imager of claim 1 , wherein the method performed by said optical system further comprises using said captured image energy to derive control information capable of being used to steer an ordinance to a target.
4. The imager of claim 3 further, wherein the method performed by said optical system further comprises locating a laser spot of said decoded laser energy on said image.
5. The imager of claim 1 wherein said decoding comprises demodulating pulse modulated data from said decoded laser energy.
6. The imager of claim 5 wherein said pulse modulated data comprises target tracking information from a target designator.
7. The imager of claim 1 , wherein the method performed by said optical system further comprises:
focusing images to said first sub-window of said FPA; and
snapshot exposing said first sub-window of said FPA, thereby capturing image energy focused by said optical system to said first sub-window.
8. A method comprising;
focusing, using an optical system, laser energy comprising a first field-of-view to a first sub-window of an FPA;
focusing, using said optical system, images comprising a second field-of-view identical to said first field-of-view to a second sub-window of said FPA,
pixel scanning said first sub-window at an exposure rate that matches a predetermined pulse repetition frequency (PRF) to thereby decode laser energy focused on said first sub-window at said predetermined PRF; and
snapshot exposing said second sub-window of said FPA, thereby capturing image energy focused by said optical system to said second sub-window.
9. The method of claim 8 further comprising using said decoded laser energy to derive control information capable of being used to steer ordinance to a target.
10. The method of claim 8 further comprising using said captured image energy to derive control information capable of being used to steer an ordinance to a target.
11. The method of claim 10 further comprising locating a laser spot of said decoded laser energy on said image.
12. The method of claim 8 wherein said decoding comprises demodulating pulse modulated data from said decoded laser energy.
13. The method of claim 12 wherein said pulse modulated data comprises target tracking information from a target designator.
14. The method of claim 8 further comprising:
focusing images to said first sub-window of said FPA; and
snapshot exposing said first sub-window of said FPA, thereby capturing image energy focused on said first sub-window.
15. A method comprising:
focusing, using an optical system, laser energy to a first sub-window of a focal plane array (FPA);
pixel scanning said first sub-window at an exposure rate that matches a predetermined pulse repetition frequency (PRF) to thereby decode laser energy focused on said first sub-window at said predetermined PRF;
focusing image energy to a second sub-window of said FPA;
snapshot exposing said second sub-window of said FPA, thereby capturing image energy focused on said second sub-window;
focusing image energy to said first-sub-window of said FPA;
switching said first sub-window to snapshot expose said first sub-window of said FPA, thereby capturing image energy focused on said first sub-window; and
combining said image energy focused on said first sub-window with said image energy focused on said second sub-window to recover pixel resolution of said FPA by image processing super-resolution techniques.