A Miniature Silicon Photo-Acoustic Detector for Gas Monitoring Applications

An increased focus on pollution, health and safety, as well as the introduction of new legislation, has led to increased interest in environmental absorption path and a PA cell with a built-in thermopile (Figure J). The source is modulated at a frequency of 20Hz. The infrared light is emitted with an approximate greybody spectral distribution. Presence of 5 ppm SF6. Many other gases are suitable to be monitored by this technique; and an appreciable potential sensitivity enhancement remains to be exploited.