Dual-mode SAL/IR imaging
View Patent ↗Dual mode SAL/IR imaging seekers are described herein. In some embodiments, a dual-mode SAL/IR imaging seeker described herein includes a focal plane array (FPA), an objective optical assembly providing a common optical path to the FPA for incident laser radiation of a first wavelength band and incident ambient radiation of a second wavelength band non-overlapping with the first wavelength band, a first optical filter operable to selectively pass the incident laser radiation to the FPA in a transmissive mode and selectively block the incident laser radiation from the FPA in a non-transmissive mode and a second optical filter assembly operable to selectively pass the incident ambient radiation to the FPA in a transmissive mode and selectively block the incident ambient radiation from the FPA in a non-transmissive mode.
1. A dual-mode SAL/IR imaging seeker comprising:
a focal plane array (FPA);
an objective optical assembly providing a common optical path to the FPA for incident laser radiation of a first wavelength band and incident ambient radiation of a second wavelength band non-overlapping with the first wavelength band;
a first optical filter operable to selectively pass the incident laser radiation of the first wavelength band to the FPA in a transmissive mode and selectively block the incident laser radiation of the first wavelength band from the FPA in a non-transmissive mode, wherein the first wavelength band is from 10 nm to 20 nm wide within a wavelength range from 700 nm to 1700 nm; and
a second optical filter operable to selectively pass the incident ambient radiation of the second wavelength band to the FPA in a transmissive mode and selectively block the incident ambient radiation from the FPA in a non-transmissive mode, wherein the second wavelength band includes wavelengths in the range from 700 nm to 1700 nm not included in the first wavelength band.
2. The dual-mode SAL/IR imaging seeker of claim 1 , wherein the first optical filter is electrically switchable between the transmissive mode and the non-transmissive mode.
3. The dual-mode SAL/IR imaging seeker of claim 1 , wherein the first optical filter is configured and adapted to selectively pass incident laser radiation that includes scattered laser radiation.
4. The dual-mode SAL/IR imaging seeker of claim 1 , wherein the first optical filter is configured and adapted to selectively pass incident laser radiation transmitted from a laser target designator.
5. The dual-mode SAL/IR imaging seeker of claim 1 , wherein the second optical filter is configured and adapted to selectively pass incident ambient radiation that includes ambient infrared radiation.
6. The dual-mode SAL/IR imaging seeker of claim 1 , wherein the second optical filter is configured and adapted to selectively pass incident ambient radiation that includes ambient infrared radiation reflected from a target.
7. The dual-mode SAL/IR imaging seeker of claim 1 , wherein the optical bandpass filter assembly includes a plurality of second bandpass filters, each second bandpass filter covering a subset of wavelengths of the second wavelength band.
8. The dual-mode SAL/IR imaging seeker of claim 7 , wherein the second bandpass filters are electrically switchable between the radiation transmissive mode and the non-transmissive mode.
9. The dual-mode SAL/IR imaging seeker of claim 1 , wherein the focal plane is undivided for combined sensing of the laser radiation and imaging of the infrared radiation.
10. A method of making a dual-mode SAL/IR imaging seeker comprising:
providing a focal plane array (FPA);
providing an objective optical assembly establishing a common optical path to the FPA for incident laser radiation of a first wavelength band and incident ambient radiation of a second wavelength band non-overlapping with the first wavelength band;
positioning a first optical filter in the common optical path operable to selectively pass the incident laser radiation of the first wavelength band to the FPA in a transmissive mode and selectively block the incident laser radiation from the FPA in a non-transmissive mode, wherein the first wavelength band is from 10 nm to 20 nm wide within a wavelength range from 700 nm to 1700 nm; and
positioning a second optical filter assembly in the common optical path operable to selectively pass the incident ambient radiation of the second wavelength band to the FPA in a transmissive mode and selectively block the incident ambient radiation from the FPA in a non-transmissive mode, wherein the second wavelength band includes wavelengths in the range from 700 nm to 1700 nm not included in the first wavelength band.
11. A method of guiding a weapon to a target comprising:
actively acquiring and tracking a target with a dual-mode SAL/IR imaging system by substantially isolating laser radiation of a first wavelength band reflected from the target from ambient infrared radiation reflected from the target and sensing the isolated laser radiation with a focal plane array (FPA) of the dual mode SAL/IR imaging system, wherein the dual-mode SAL/IR system includes:
an objective optical assembly providing a common optical path to the FPA for incident laser radiation of a first wavelength band and incident ambient infrared radiation of a second wavelength band non-overlapping with the first wavelength band;
a first optical filter operable to selectively pass the incident laser radiation of the first wavelength band to the FPA in a transmissive mode and selectively block the incident laser radiation from the FPA in a non-transmissive mode, wherein the first wavelength band is from 10 nm to 20 nm wide within a wavelength range from 700 nm to 1700 nm; and
a second optical filter assembly operable to selectively pass the incident ambient infrared radiation of the second wavelength band to the FPA in a transmissive mode and selectively block the incident ambient infrared radiation from the FPA in a non-transmissive mode, wherein the second wavelength band includes wavelengths in the range from 700 nm to 1700 nm not included in the first wavelength band.
12. The method of claim 11 , wherein isolating the reflected laser radiation of the first wavelength band includes placing the first optical filter in the-transmissive mode and placing the second optical filter assembly in the non-transmissive mode.
13. The method of claim 11 further comprising switching from active tracking of the target to passive imaging and tracking of the target with the SAL/IR imaging system by selectively blocking the reflected laser radiation from the FPA and passing the ambient infrared radiation reflected from the target to the FPA.
14. The method of claim 13 , wherein selectively blocking the reflected laser radiation and passing the reflected ambient infrared radiation includes placing the first optical filter in the non-transmissive mode and placing the second optical filter assembly in transmissive mode.
15. The method of claim 14 , further comprising alternating between active tracking and passive tracking of the target until the weapon is delivered to the target.
16. The method of claim 14 , further comprising alternating between active and passive tracking of the target until passive imaging resolves the target to a predetermined threshold.
17. The method of claim 16 , wherein passive tracking continues until the weapon is delivered to the target.