Patent ID: 7423756

Claim:
A gas filter correlation radiometry (GFCR) system, comprising: an optical train having an entrance aperture, said optical train adapted to receive light from a scene of interest at said entrance aperture, said optical train (i) using the light to form an image of the scene at a focal plane within said optical train, (ii) confining light from a selected field-of-view of the image at said focal plane to a spectral band at which a gas of interest absorbs, and (iii) splitting the confined light into first and second paths; light-producing means for selectively producing a calibrating light from within said optical train at said focal plane wherein a portion of said calibrating light traverses each of said first and second paths; a region that is substantially non-interfering with respect to said spectral band, said region being disposed in said first path; a gas cell filled with the gas of interest, said gas cell disposed in said second path; detecting means for independently detecting light passed through said region and passed through said gas cell and for generating output signals indicative of said light so-detected; and processing means coupled to said detecting means for processing said output signals wherein said output signals resulting from the light from said selected field-of-view of the image are used to generate a measure of the gas of interest and said output signals resulting from said portion of said calibrating light are used to calibrate said GFCR system.