Patent ID: 6841778

Claim:
An apparatus for determining the particulate content of an exhaust plume of a vehicle, comprising: an ultraviolet light source for propagating through the exhaust plume ultraviolet light having a predetermined ultraviolet wavelength; an infrared light source for propagating through the exhaust plume infrared light; an ultraviolet light detector for receiving said ultraviolet light after passing through the exhaust plume and producing an ultraviolet signal representative of the reduction in intensity of said predetermined wavelength of ultraviolet light due to scattering by particles whose diameter is greater than said predetermined ultraviolet wavelength; an infrared detector for receiving said infrared light after passing through the exhaust plume and producing an infrared signal representative of the reduction in intensity of the infrared light; and a processor for determining from the ultraviolet signal the density of particles in the exhaust plume whose diameter is greater than said predetermined wavelength of ultraviolet light, and for determining from the infrared signal the density of carbon dioxide in the exhaust plume, said processor determining the particulate content of the exhaust plume by computing the ratio of the density of the particles whose diameter is greater than said predetermined wavelength of ultraviolet light to the density of the carbon dioxide.