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 thermal imaging system for use in an internal combustion engines employs a removable optical housing that is inserted through a hole in the cylinder wall. 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 the preferred 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. A thermocouple or heat flux gauge can be mounted to the cylinder wall within the field of view of the thermal imaging system to provide a reference point for temperature measurements.