| 摘要 |
<p>A device as described whereby the concentration of a gas such as alcohol vapour can be measured using radiation absorption techniques in a pair of chambers. The chambers are elongated tubes, the first having a window at one end through which infra red radiation can pass with an optical reflector at the two ends of each tube so that radiation from a source and focused by an ellipsoidal reflector passes through the first tube in both directions and thence through the second. The reflected radiation leaves the second tube through a second window in the side of the tube, from where it passes to a detector. Passing the radiation in series through two or more parallel arranged chambers, conveniently located within a common housing increases the sensitivity.</p> |
