Method and system for pupil detection for security applications
View Patent ↗An object to be detected is illuminated by a single broadband light source or multiple light sources emitting light at different wavelengths. The light is captured by an imager, which includes a light-detecting sensor covered by a hybrid filter.
1. A system for pupil detection, comprising:
a source for emitting light towards an object;
a first imager;
a first hybrid filter positioned between the source and the first imager; and
a first controller connected to the first imager for generating an alert signal when a pupil is detected, wherein detection of the pupil indicates detection of a person moving into a field of view of the imager.
2. The system of claim 1 , further comprising:
a second imager;
a second hybrid filter positioned between the second imager and the source;
a second controller connected to the second imager; and
a stereo controller connected to the first and second controllers for generating at least one three-dimensional image.
3. The system of claim 1 , further comprising a timer connected to the controller.
4. The system of claim 1 , further comprising a controlled device connected to the first controller.
5. The system of claim 1 , further comprising an input device connected to the first controller, wherein the input device is implemented as a computer operating pursuant to a security program and is configured to alter a parameter of the first controller.
6. The system of claim 1 , wherein the first imager generates the one or more images continuously and the first controller continuously analyzes the one or more images.
7. The system of claim 1 , wherein the first imager includes a light-detecting sensor.
8. The system of claim 7 , wherein the light-detecting sensor simultaneously detects the amount of light received at or near the multiple wavelengths of interest.
9. The system of claim 7 , wherein the light-detecting sensor alternately detects the amount of light received at or near each wavelength of interest.
10. The system of claim 1 , wherein the hybrid filter comprises a first filter layer and a patterned filter layer, wherein the first filter layer passes light at or near the multiple wavelengths of interest and blocks light at all other wavelengths, and wherein the patterned filter layer includes regions that transmit light received at or near one wavelength of interest and block light received at or near the other wavelengths of interest.
11. The system of claim 10 , wherein the patterned filter layer includes regions that do not block any light and receive light at or near all of the wavelengths of interest.
12. The system of claim 10 , wherein the first filter layer comprises a dielectric stack filter.
13. The system of claim 12 , wherein the dielectric stack filter comprises a colored glass filter.
14. The system of claim 12 , wherein the dielectric stack filter comprises N coupled-cavity resonators stacked together, where N is an integer number.
15. The system of claim 10 , wherein the patterned filter layer is comprised of one of patterned dye-doped polymers, patterned pigment-doped polymers, patterned interference filters, patterned reflective filters, or patterned absorbing filters.
16. The system of claim 1 , wherein the source comprises a single broadband light source emitting light at the multiple wavelengths of interest.
17. The imaging system of claim 1 , wherein the source comprises a first light source emitting light at the first wavelength and a second light source emitting light at the second wavelength.
18. The imaging system of claim 17 , wherein the first light source is positioned at a first angle relative to the axis of the light-detecting sensor and the second light source is positioned at a second angle relative to the axis of the light-detecting sensor where the second angle is larger than the first angle.
19. A method for wavelength-dependent detection, comprising:
receiving light from an object, wherein the light includes light propagating at two or more wavelengths of interest;
discriminating between light received at or near the wavelengths of interest while simultaneously blocking light received at all other wavelengths;
detecting the amount of light received at or near each wavelength of interest and generating one or more images using the light received at or near the wavelengths of interest;
determining whether at least one of the one or more images includes a pupil; and
generating an alert signal when at least one of the images includes a pupil, wherein detection of the pupil indicates detection of a person moving into a field of view of the imager.
20. The method of claim 19 , further comprising determining a difference between the amount of light received at each of the wavelengths of interest.
21. The method of claim 19 , wherein determining whether at least one of the one or more images includes a pupil comprises continuously determining whether at least one of the one or more images includes a pupil.
22. The method of claim 19 , wherein determining whether at least one of the one or more images includes a pupil comprises determining at regular intervals whether at least one of the one or more images includes a pupil.