Optical system for determining the angular position of a radiating point source and method of employing
View Patent ↗An optical system for determining the angular position of a radiating point source is disclosed, wherein radiation from a point source travels through a mask and onto the surface of a sensor. A preferred embodiment employs a plurality of mask transmission frequencies and a detector designed to be sensitive to the phases of the frequencies. A computer measures the phases of a plurality of detected image frequencies. Measurement of the particular phases of the frequency components allows determination of the image shift on the detector axis. The image shift is then used to compute angle of incidence of the light source upon the detector. The preferred embodiment employs a refractive window, hence the angle of incidence between point radiating source and mask are determined using the window index of refraction and refraction equations. Applications include within the cockpit of a jet aircraft.
1. A system for determining the angular position and distance of a radiating source with respect to a detector, comprising:
a) a radiation detector;
b) a mask spaced in front of said detector, said mask having a plurality of transmission frequencies;
c) recording means for recording an image cast onto said detector by radiation passing through said mask;
d) computing means for computing data related to said image;
e) identifying means for identifying phases of a plurality of frequencies of said image and creating signals corresponding thereto;
f) determining means for determining angular position of said radiation source with respect to said detector;
g) said determining means receiving said signals and, therefrom, determining said angular position of said radiation source with respect to said detector.
2. The system of claim 1 , wherein apertures in said mask comprise a transmissivity pattern varying in one dimension.
3. The system of claim 2 , wherein said one dimension comprises a Y-axis.
4. The system of claim 1 , wherein said detector and mask are planar and lie in parallel planes.
5. The system of claim 4 , wherein said mask and detector are spaced apart by a known distance.
6. The system of claim 1 , wherein said mask is spaced from said detector by a refractive medium or window.
7. The system of claim 1 , wherein said detector includes a plurality of parallel arrays, each array detecting phase of a unique mask frequency.
8. The system of claim 7 , wherein there are three mask frequencies related to one another by the ratio F 0 :5F 0 :25F 0 , where F 0 is a fundamental frequency.
9. The system of claim 8 , wherein an array of said detector detects phase of said fundamental frequency and provides coarse measurement.
10. The system of claim 9 , wherein an array of said detector detects phase of said frequency 25F 0 and provides fine measurement.
11. The system of claim 1 , wherein said detector includes a plurality of parallel detector arrays for identifying said phases.
12. The system of claim 11 , wherein said plurality parallel detector arrays consist of a coarse, medium, and fine resolution array each responsive to phases of a particular mask image frequency.
13. The system of claim 1 , wherein two orthogonal and coplanar arrangements of masks are used on a common window and two underlying orthogonal and coplanar detectors are located on a common substrate to create a two-dimensional angle of incidence sensor.
14. The system of claim 1 , located within an aircraft cockpit.
15. The system of claim 14 , wherein said aircraft comprises a jet.
16. The system of claim 15 , wherein said jet aircraft has a canopy that filters a portion of light spectrum including an optical detection bandwidth.
17. The system of claim 16 , wherein said optical detection bandwidth comprises a combined response of an optical detector bandwidth and an overlying detector filter bandwidth.
18. The system of claim 17 , wherein said optical detection bandwidth includes an ultraviolet range and uses a detector filter that removes light above a wavelength of 400 nm.
19. The system of claim 17 , wherein said optical detection bandwidth includes an infrared range and uses a detector filter that removes light below a wavelength of 1700 nm.
20. The system of claim 1 , employing a plurality of detectors that detect emitter light angle of incidence in at least one dimension.
21. A system for determining the angular position and distance of a radiating source with respect to a detector, comprising:
a) a radiation detector, said detector including a plurality of parallel arrays, each array detecting phase of a unique mask frequency;
b) a mask spaced in front of said detector, said mask having a plurality of transmission frequencies, said mask having apertures comprising a transmissivity pattern varying in one dimension, said mask and detector each being planar and lying in parallel planes;
c) recording means for recording an image cast onto said detector by radiation passing through said mask;
d) computing means for computing data related to said image;
e) identifying means for identifying phases of a plurality of frequencies of said image and creating signals corresponding thereto;
f) determining means for determining angular position of said radiation source with respect to said detector;
g) said determining means receiving said signals and, therefrom, determining said angular position of said radiation source with respect to said detector.
22. The system of claim 21 , wherein said mask and detector are spaced apart by a known distance.
23. The system of claim 21 , wherein said mask is spaced from said detector by a refractive medium or window.
24. The system of claim 21 , wherein there are three mask frequencies related to one another by the ratio F 0 :5F 0 :25F 0 , where F 0 is a fundamental frequency.
25. The system of claim 24 , wherein a first array of said detector detects phase of said fundamental frequency and provides coarse measurement and a second array of said detector detects phase of said frequency 25F 0 and provides fine measurement.
26. The system of claim 21 , wherein said plurality parallel detector arrays consist of a coarse, medium, and fine resolution array each responsive to phases of a particular mask image frequency.
27. The system of claim 21 , wherein two orthogonal and coplanar arrangements of masks are used on a common window and two underlying orthogonal and coplanar detectors are located on a common substrate to create a two-dimensional angle of incidence sensor.
28. The system of claim 21 , located within a jet aircraft cockpit.
29. The system of claim 28 , wherein said jet aircraft has a canopy that filters a portion of light spectrum including an optical detection bandwidth.
30. The system of claim 29 , wherein said optical detection bandwidth comprises a combined response of an optical detector bandwidth and an overlying detector filter bandwidth.
31. The system of claim 30 , wherein said optical detection bandwidth includes an ultraviolet range and uses a detector filter that removes light above a wavelength of 400 nm.
32. The system of claim 31 , wherein said optical detection bandwidth further includes an infrared range and uses a detector filter that removes light below a wavelength of 1700 nm.