Detection and classification of light sources using a diffraction grating
A system mounted in a vehicle for classifying light sources. The system includes a lens and a spatial image sensor. The lens is adapted to provide an image of a light source on the spatial image sensor. A diffraction grating is disposed between the lens and the light source. The diffraction grating is adapted for providing a spectrum. A processor is configured for classifying the light source as belonging to a class selected from a plurality of classes of light sources expected to be found in the vicinity of the vehicle, wherein the spectrum is used for the classifying of the light source. Both the image and the spectrum may be used for classifying the light source or the spectrum is used for classifying the light source and the image is used for another driver assistance application.
1. A system mountable in a vehicle, the system for classifying a light source, the system comprising:
a spatial image sensor;
a lens disposed between the light source and the spatial image sensor, and configured to provide an image of the light source on the spatial image sensor;
a diffraction grating or prism disposed between the lens and the light source, wherein the diffraction grating or prism is configured to direct a first spectrum of a light of the light source and a second spectrum of the light of the light source onto the spatial image sensor, the first spectrum being different from the second spectrum; and
a processor configured to:
identify a first location of the first spectrum and a second location of the second spectrum projected in a plane defined by the spatial image sensor; and
classify the light source as belonging to a class selected from a plurality of classes of light sources based on a distance between the first and second locations.
2. The system of claim 1 , wherein at least one of the first or second spectrum is sensed by the spatial image sensor.
3. The system of claim 1 , wherein the light source is selected from the group consisting of streetlights, headlights, taillights and traffic signs.
4. The system of claim 1 , further comprising a hood enclosure configured to reduce a field of view of the lens to a predetermined degree so that light from another light source located outside of the reduced field of view does not superimpose at least one of the first or second spectrum.
5. The system of claim 1 , wherein the processor uses the image of the light source and at least one of the first or second spectrum to classify the light source.
6. The system of claim 1 , wherein the lens and the diffraction grating or prism are formed at different optical surfaces of a single optical element.
7. A method of classifying light sources using a system including a camera equipped with a lens and a spatial image sensor, the method comprising:
providing, by the lens disposed between the light source and the spatial image sensor, an image of a light source on the spatial image sensor;
directing, by a diffraction grating or prism disposed between the lens and the light source, a first spectrum of a light of the light source and a second spectrum of the light of the light source onto the spatial image sensor, the first spectrum being different from the second spectrum;
identifying, by a processor, a first location of the first spectrum and a second location of the second spectrum projected in a plane defined by the spatial image sensor; and
classifying, by the processor, based on a distance between the first and second locations, the light source as belonging to a class selected from a plurality of classes of light sources.
8. The method of claim 7 , further comprising reducing a field of view of the lens to a predetermined degree using a hood enclosure so that light from another light source located outside of the reduced field of view does not superimpose at least one of the first or second spectrum.
9. The method of claim 7 , wherein classifying is also based on the image of the light source.
10. A system mounted in a vehicle for classifying a light source, comprising:
an image sensor;
a lens configured to form an image of the light source on the image sensor;
a dispersive optical element disposed between the lens and the light source and configured to form a first spectrum of a light of the light source and a second spectrum of the light of the light source on the image sensor, the first spectrum being different from the second spectrum;
a processor configured to classify the light source as belonging to a class selected from a plurality of classes of light sources based on a distance between a first location of the first spectrum and a second location of the second spectrum projected in a plane defined by the spatial image sensor; and
a hood enclosure including a portion disposed within a field of view of the lens to reduce the field of view to a predetermined degree such that light from another light source located outside of the reduced field of view does not superimpose at least one of the first or second spectrum.
11. The system of claim 10 , wherein at least one of the first or second spectrum is sensed by the spatial image sensor.
12. The system of claim 10 , wherein the light source is selected from the group consisting of streetlights, headlights, taillights and traffic signs.
13. The system of claim 10 , wherein the processor uses the image of the light source and at least one of the first or second spectrum to classify the light source.
14. The system of claim 10 , wherein the lens and the dispersive optical element are formed at different optical surfaces of a single optical element.
15. A method of classifying a light source, comprising:
forming, by a lens, an image of the light source on an image sensor;
forming, by a dispersive optical element disposed between the lens and the light source, a first spectrum of a light of the light source and a second spectrum of the light of the light source on the image sensor, the first spectrum being different from the second spectrum;
reducing, by a hood enclosure including a portion disposed within a field of view of the lens, the field of view to a predetermined degree such that light from another light source located outside of the reduced field of view does not superimpose at least one of the first spectrum or the second spectrum; and
classifying, by a processor, the light source as belonging to a class selected from a plurality of classes of light sources based on a distance between a first location of the first spectrum and a second location of the second spectrum projected in a plane defined by the spatial image sensor.
16. A system mounted in a vehicle for classifying a light source, comprising:
an image sensor;
a lens configured to form an image of the light source on the image sensor;
a dispersive optical element disposed between the lens and the light source and configured to form a first spectrum of a light of the light source and a second spectrum of the light of the light source on the image sensor, the first spectrum being different from the second spectrum; and
a processor configured to:
identify a first location of the first spectrum projected in a plane defined by the spatial image sensor using a first fixed distance between the image and the first spectrum respectively formed on the image sensor;
identify a second location of the second spectrum projected in the plane defined by the spatial image sensor using a second fixed distance between the image and the second spectrum respectively formed on the image sensor; and
classify the light source as belonging to a class selected from a plurality of classes of light sources based on a distance between the first location and the second location.
17. The system of claim 16 , further comprising:
a hood enclosure including a portion disposed within a field of view of the lens to reduce the field of view to a predetermined degree such that light from another light source located outside of the reduced field of view does not superimpose at least one of the first or second spectrum.
18. The system of claim 16 , wherein the processor uses the image of the light source and at least one of the first or second spectrum to classify the light source.
19. The system of claim 16 , wherein the lens and the dispersive optical element are formed at different optical surfaces of a single optical element.
20. A method of classifying a light source, comprising:
forming, by a lens, an image of the light source on an image sensor;
forming, by a dispersive optical element disposed between the lens and the light source, a first spectrum of a light of the light source and a second spectrum of the light of the light source on the image sensor, the first spectrum being different from the second spectrum;
identifying, by a processor, a first location of the first spectrum in a plane defined by the spatial image sensor using a first fixed distance between the image and the first spectrum respectively formed on the image sensor;
identifying, by a processor, a second location of the second spectrum in a plane defined by the spatial image sensor using a second fixed distance between the image and the second spectrum respectively formed on the image sensor; and
classifying, by the processor, the light source as belonging to a class selected from a plurality of classes of light sources based on a distance between the first location and the second location.