| 摘要 |
<p>The detection device for selectively detecting gas comprises a light source arrangement (10) comprised of an emitter (11) arranged in an ellipsoïdal reflector (14) almost closed. The ellipsoïdal reflector (14) may contain the measurement gas; in that case, the light coming out of the reflector is brought onto a filter (31). In an alternative, the reflector contains a non absorbing charge, and a photo-acoustic detecting cell (41) containing the measurement gas. This requires an acoustic decoupling during the measurement and the exchange of gas. A plurality of devices are adapted to this effect: capillary tube (71) in the wall of the cell; stop devices for the liquid (75, 76); mechanical valves (64); combination of a membrane pump with a flop valve (64).</p> |
