Laser source location system
View Patent ↗A system for detecting a direction of a source of a laser beam includes a pixelated sensor that is sensitive to the laser beam. A mask is disposed between the source of a laser beam and the pixelated sensor. The mask includes an opaque portion that is opaque to the laser beam and a window portion that is at least translucent to the laser beam. When the laser impinges upon the mask an image of the window portion is projected onto the pixelated sensor. A processor determines an angle of incidence of the laser beam with respect to the mask by determining a number of pixels that the image of the window is offset from where the image of the window would be if the laser beam had been normal to the mask.
1. A system for detecting a direction of a source of a laser beam, comprising:
(a) a pixelated sensor that is sensitive to the laser beam;
(b) a mask, disposed between the source of a laser beam and the pixelated sensor, the mask including an opaque portion that is opaque to the laser beam and a window portion that is at least translucent to the laser beam so that when the laser impinges upon the mask an image of the window portion is projected onto the pixelated sensor; and
(c) a processor that determines an angle of incidence of the laser beam with respect to the mask by determining a number of pixels that the image of the window is offset from where the image of the window would be if the laser beam had been normal to the mask.
2. The system of claim 1 , wherein the pixelated sensor comprises a two-dimensional video sensor array that is sensitive to the laser beam and selected from a list of sensor array technologies consisting of: CMOS, InGaAs, HgCdTe, Vox and InSb.
3. The system of claim 1 , wherein the mask comprises a layer of a material selected from a list consisting of: glass, quartz, sapphire, germanium, zinc selenide, and combinations thereof, on which the opaque portion is coated on one side with a coating that is opaque to the laser beam and on which the window portion is not coated with the coating.
4. The system of claim 1 , wherein the window portion has a shape that includes at least a first edge and a second edge that is transverse to the first edge.
5. The system of claim 4 , wherein the first edge is perpendicular to the second edge.
6. The system of claim 4 , wherein the angle of incidence along a first axis (α 1 ) is calculated based on a distance (A 1 ) from the first edge to the pixelated sensor and a distance (B 1 ) between an image of the first edge projected by the laser beam onto the pixelated sensor and where the image of the first edge would have been had the laser beam been normal to the mask, according to the following formula:
α
1
=
tan
-
1
(
A
1
B
1
)
and wherein the angle of incidence along a second axis (α 2 ) is calculated based on a distance (A 2 ) from the second edge to the pixelated sensor and a distance (B 2 ) between an image of the second edge projected by the laser beam onto the pixelated sensor and where the image of the second edge would have been had the laser beam been normal to the mask, according to the following formula:
α
2
=
tan
-
1
(
A
2
B
2
)
where the second axis is perpendicular to the first axis.
7. The system of claim 1 , employed in a first station that is configured to steer an outgoing laser beam toward an incoming laser beam from a second station.
8. An avionics device for locating a source of a laser beam emanating from a source position and aimed at an aircraft, comprising:
(a) a laser sensor that detects a direction from which the laser beam is sourced relative to a known point on the aircraft and that generates a laser angle signal representative thereof;
(b) a position sensor that generates a position signal indicative of the aircraft's position in three dimensions relative to a coordinate system of a predetermined frame of reference; and
(c) an attitude sensor that generates an attitude signal indicative of the aircraft's pitch, bank and yaw relative to the predetermined coordinate system; and
(d) a processor that is responsive to the laser sensor, the position sensor and the attitude sensor, that determines a source direction of the laser beam relative to the known point based on current values of the laser angle signal, the position signal and the attitude signal;
wherein the laser sensor comprises a pixelated sensor that is sensitive to the laser beam; a mask, disposed between the source of a laser beam and the pixelated sensor, the mask including an opaque portion that is opaque to the laser beam and a window portion that is at least translucent to the laser beam so that when the laser impinges upon the mask an image of the window portion is projected onto the pixelated sensor; and the processor that determines an angle of incidence of the laser beam with respect to the mask by determining a number of pixels that the image of the window is offset from where the image of the window would be if the laser beam had been normal to the mask.
9. The avionics device of claim 8 , further comprising a memory in data communication with the processor that stores a digital map of a ground surface upon which the source position is located, wherein the processor is further configured to locate the source position on the map and to generate an indication of where the source position is on the map.
10. The avionics device of claim 8 , further comprising a display upon which is displayed an image of a relevant portion of a ground surface and wherein the processor is further configured to display a graphical indication of the location of the source position on the image of a relevant portion of the ground surface.
11. The avionics device of claim 8 , wherein the pixelated sensor comprises a two-dimensional CMOS video sensor array that is sensitive to the laser beam.
12. The avionics device of claim 8 , wherein the mask comprises a layer of material selected from a list consisting of: glass, quartz, sapphire, germanium, zinc selenide, and combinations thereof, on which the opaque portion is coated on one side with a coating that is opaque to the laser beam and on which the window portion is not coated with the coating.
13. The avionics device of claim 8 , wherein the window portion has a shape that includes at least a first edge and a second edge that is transverse to the first edge.
14. The avionics device of claim 13 , wherein the first edge is perpendicular to the second edge.
15. The avionics device of claim 13 , wherein the angle of incidence along a first axis (α 1 ) is calculated based on a distance (A 1 ) from the first edge to the pixelated sensor and a distance (B 1 ) between an image of the first edge projected by the laser beam onto the pixelated sensor and where the image of the first edge would have been had the laser beam been normal to the mask, according to the following formula:
α
1
=
tan
-
1
(
A
1
B
1
)
and wherein the angle of incidence along a second axis (α 2 ) is calculated based on a distance (A 2 ) from the second edge to the pixelated sensor and a distance (B 2 ) between an image of the second edge projected by the laser beam onto the pixelated sensor and where the image of the second edge would have been had the laser beam been normal to the mask, according to the following formula:
α
2
=
tan
-
1
(
A
2
B
2
)
where the second axis is perpendicular to the first axis.
16. A system for detecting a direction of a source of a laser beam, comprising:
(a) a pixelated sensor that is sensitive to the laser beam;
(b) a mask, disposed between the source of a laser beam and the pixelated sensor, the mask including an opaque portion that is opaque to the laser beam and a window portion that is at least translucent to the laser beam so that when the laser impinges upon the mask an image of the window portion is projected onto the pixelated sensor, the window portion having a shape that includes at least a first edge and a second edge that is transverse to the first edge; and
(c) a processor that determines an angle of incidence of the laser beam with respect to the mask by determining a number of pixels that the image of the window is offset from where the image of the window would be if the laser beam had been normal to the mask,
wherein the angle of incidence along a first axis (α 1 ) is calculated based on a distance (A 1 ) from the first edge to the pixelated sensor and a distance (B 1 ) between an image of the first edge projected by the laser beam onto the pixelated sensor and where the image of the first edge would have been had the laser beam been normal to the mask, according to the following formula:
α
1
=
tan
-
1
(
A
1
B
1
)
and wherein the angle of incidence along a second axis (α 2 ) is calculated based on a distance (A 2 ) from the second edge to the pixelated sensor and a distance (B 2 ) between an image of the second edge projected by the laser beam onto the pixelated sensor and where the image of the second edge would have been had the laser beam been normal to the mask, according to the following formula:
α
2
=
tan
-
1
(
A
2
B
2
)
where the second axis is perpendicular to the first axis.
17. The system of claim 16 , wherein the pixelated sensor comprises a two-dimensional video sensor array that is sensitive to the laser beam and selected from a list of sensor array technologies consisting of: CMOS, InGaAs, HgCdTe, Vox and InSb.
18. The system of claim 16 , wherein the mask comprises a layer of a material selected from a list consisting of: glass, quartz, sapphire, germanium, zinc selenide, and combinations thereof, on which the opaque portion is coated on one side with a coating that is opaque to the laser beam and on which the window portion is not coated with the coating.
19. The system of claim 16 , wherein the first edge is perpendicular to the second edge.