Abstract: Apparatus for detecting a target gas in a monitored space (105) comprises two laser diodes (101) and (114) driven by drive circuits (103) and (115) at electrical frequencies f and f? that are not harmonically related. The lasers (101) and (114) operate at mean wavelengths ?1 and ?2 respectively close to two different absorption lines of the target gas and are scanned over wavelength ranges ??1 and ??2 respectively. The outputs from the lasers (101) and (114) are collimated by an optical element (104) and delivered to a receiver element (106) after passing through the space (105). The receiver element (106) focuses the radiation from both lasers onto a detector (107) where the optical signals are combined into a single electrical signal with principal frequency components f and f?.

Abstract: The present invention relates to the infrared detection of hydrocarbon gases; infrared light from a source (10) is passed through a filter (12) to produce a beam (14) passing through a space (16), which can potentially contain hydrocarbon gases. The wavelength of the beam (14) contains a wavelength that is absorbed by hydrocarbon gases (sample wavelength) and a wavelength that is not absorbed by hydrocarbon gases (reference wavelength). The beam (14) falls on a detector that contains sensors (22, 24) that receive light that has passed through respective filters (18, 20). Sample filter (20) allows a single wavelength to be transmitted; reference filter (18) allows two wavelength bands to be transmitted, the bands having wavelengths located on either side of the sample wavelength in order to eliminate the effects of atmospheric conditions that are unconnected with hydrocarbon gases.

Abstract: An apparatus and method for improving the cleaning and deicing effectiveness of a washer fluid in a motor vehicle before spraying it against a windshield, headlamps, etc., utilizes the heat from the engine coolant to elevate the temperature of the washer fluid. In addition, a mixing valve arrangement is used to maintain the temperature of the heated washer fluid at a predetermined difference value from that of the windshield, etc., outside surface. The cleaning effectiveness of the heated washer fluid is superior to that of ambient temperature washer fluid, and is also advantageous for deicing purposes.