| 摘要 |
<p>An instrument for determining the concentration of a particular gas that might be present in a sample has no moving parts and is extremely compact and inexpensive. A novel waveguiding structure (12) serves both as an optical element and as the sample chamber. As an optical element, the waveguiding structure collects radiation from a blackbody source (26) located at the entrance end (14) of the waveguiding structure and conducts the radiation through the waveguiding structure, concentrating it on two infrared detectors (40 and 42) mounted at the opposite end (16) of the waveguiding structure. As a sample chamber, the waveguiding structure causes the radiation to undergo multiple reflections that result in the average path length being substantially greater than the physical length of the waveguiding structure. Each of the detectors has its own optical filter, and a baffle (44) assures that each detector responds only to radiation which has passed through its filter. One filter (36) defines a spectral passband that coincides with the infrared absorption band of the gas to be measured. The other filter (38) defines a non-absorbing or neutral passband. The electrical signals produced by the detectors are processed to provide a ratio, the value of which is related to the concentration of the particular gas to be detected.</p> |
