Patent ID: 7375814

Claim:
An apparatus for providing an indication of the presence of a gas of interest having a background concentration within a scene having a surface, comprising: a backscatter absorption gas measurement system to generate a plurality of light pulses to illuminate the surface and determine an indication of absorption by the gas of interest within the scene, wherein the generated light pulses comprise a plurality of beams comprising a first plurality of beams having a first wavelength of light and a second wavelength of light and an alternating second plurality of beams having a first wavelength of light and a third wavelength of light, wherein the first wavelength of light is absorbed by the gas of interest; a range measurement system to determine an indication of the distance from said backscatter absorption gas measurement system to the surface illuminated by said backscatter absorption gas measurement system, wherein the distance is determined from the round-trip time-of-flight of light pulses of the first wavelength; and a processor to combine the determined indication of absorption and the determined indication of the distance to provide an indication of the presence of the gas of interest in excess of the background concentration, wherein the determined indication of absorption is a differential absorption measurement determined by said processor from said second and third wavelength, and wherein the indication of the presence of the gas of interest includes a presentation of an image of the scene on a display wherein the image comprises a plurality of pixels, wherein each pixel corresponding to a portion of the surface is sufficiently illuminated to perform at least one absorption determination and one distance determination.