Patent ID: 6211521
Filing Date: 2001-04-03
Classification: G01J,G02B,H04N

Abstract:
An imager to provide a plurality of electrical signals in response to electromagnetic radiation incident upon the imager, the imager comprising:a plurality of pixel sensors, wherein each pixel sensor belonging to the plurality of pixel sensors comprises a filter substantially transparent to infrared radiation and having a visible radiation pass spectrum and wherein each pixel sensor is to provide a signal responsive to electromagnetic radiation propagating through its filter;an infrared pixel sensor comprising:a pixel circuit; anda plurality of filters to form a composite filter, each filter belonging to the plurality of filters substantially transparent to infrared radiation and having a visible radiation pass spectrum, wherein the composite filter is substantially opaque to visible radiation, wherein the composite filter is proximal to the pixel circuit so as to substantially prevent visible radiation from propagating through the composite filter and being absorbed by the pixel circuit, and wherein the infrared pixel sensor is to provide an electrical signal indicative of electromagnetic radiation propagating through the composite filter; anda differencing circuit coupled to the plurality of pixel sensors and the infrared pixel sensor to provide image signals, each image signal indicative of the difference between the signal provided by the infrared pixel sensor and one of the signals provided by the pixel sensors.