Abstract: A thermal imaging system for use in an internal combustion engine employs a removable optical housing that is inserted through a hole in the cylinder wall or the cylinder head. The distal end of the housing supports a lens made of a material such as polycrystalline spinel or sapphire to provide a desired field of view within the cylinder and to project an image from the field of view through the internal passageway of the optical housing. A camera receives and records the image provided by the lens and optical housing. In one embodiment, the distal portion of the optical housing is secured to the cylinder wall by means of threads or a breech-mount mechanism to permit quick and easy removal and cleaning of the lens. In another embodiment, the distal end of the optical housing is inserted into the cylinder through a spark plug housing. The optical housing is secured to the cylinder head by a formed hole in a support bracket.

Abstract: A gas analysis device for the remote detecting, measuring and recording of NO, CO, CO.sub.2, HC, and H.sub.2 O levels from the exhaust (30) of moving motor vehicles (28) utilizes a source (11) of collimated infrared and ultraviolet radiation (15) and includes a detector unit (16) positioned on the opposite side of the roadway for receiving and measuring the infrared and ultraviolet radiation from the source (11) tranmitted through the vehicle exhaust. The detector unit splits the combined infrared and ultraviolet radiation into separate infrared and ultraviolet beams (42) and (40). The ultraviolet beam is diffracted onto a photodiode array in a spectrometer that generates a signal indicative of NO in the vehicle exhaust. A rotating reflector (27) time-multiplexes the infrared beam to a plurality of infrared sensors that generate electrical signals indicative of, for example, CO, CO.sub.2, HC, and H.sub.2 O in the vehicle exhaust. A computer (17) then computes the relative concentrations of CO, CO.sub.