| 摘要 |
A spectrometric multigas analyzer is disclosed utilizing substantially isobaric temperature modulation of a gaseous sample in a highly reflective, random path, optical cavity or chamber. Multiple hot and cold ports on opposite sides of the chamber, and a gas recirculation circuit including a heating chamber, thermal regenerator, and cooling chamber, facilitate the alternate replacement of hot gas with cold gas and cold gas with hot gas in the optical chamber each cycle at a frequency of at least several Hertz, thereby producing, by gases of interest in the sample, a modulated spectral infrared emission and a modulated spectral radiant absorption of radiance from a radiant source shining into the optical chamber, which radiant source also provides heat for the heating chamber. For each substance of interest in the gaseous fluid sample, a pair of radiance detectors looking through a pair of optical filters monitor the combined modulated emission/modulated absorption signal from that substance in the optical chamber, whereby its concentration in the sample can be monitored. The temperature modulation also produces a small pressure modulation in a room or building surrounding the device, and certain actions by intruders can cause detectable changes in pressure modulation amplitudes in chambers of the building, which can be monitored by pressure sensors. Thus the device can be used for detecting and monitoring gases, vapors, aerosols, particulates and intruders, e.g., as a combined burglar, fire, and toxic gas alarm.
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