Patent ID: 7580545

Claim:
A pupil detection system, comprising: an imager operable to capture images of the pupils, wherein the imager comprises a hybrid filter comprising: a dual-band narrowband filter with a first transmission peak at a first wavelength of a first light source and a second transmission peak at a second wavelength of a second light source, wherein the dual-band narrowband filter is configured to substantially block wavelengths of light other than approximately the first wavelength and the second wavelength; and a patterned filter layer to receive light at the first and second wavelength from the dual-band narrowband filter, wherein the patterned filter layer comprises: areas of a first filter characteristic to transmit light at approximately the first wavelength to corresponding pixels of the imager; and areas of a second filter characteristic to transmit light at approximately the second wavelength to other corresponding pixels of the imager; and a processing unit operable to generate a difference image using the captured images, wherein the difference image indicates a position of the pupils due to differential reflectivity from retinal return in the captured images, and to determine a gaze direction for the pupils using the difference image.