Measurement of low concentration gases
OwnerHorst Preier, Wolfgang Riedelinventors
Life of this patent
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Abstract
Infrared radiation from a laser is directed in part or intermittently through a sample containing a low concentration gas in a host gas. The other part or the interspersed radiation by-passes the sample. Emitted and transmitted radiation is separately detected and the ratio is formed representing relative transmission. The frequency of the laser is varied so that different frequencies but within the same absorbtion band of the gas to be detected are used. The relative transmissions for different frequencies are used to calculate electrically the concentration of the gas.
Claims11
Method of determining the concentration of a particular, infrared absorbing gas in a host gas under pressure and contained therein at a small concentration comprising the steps of:
- providing laser generated infrared radiation including varying the frequency of the generated narrow-banded radiation to obtain at least two different and distinct laser frequencies but with in the range of a pressure widened band of an infrared absorption line;
- detecting, sampling and holding sequentially and separately for each of said frequencies, the intensity of the emitted radiation as provided;
- detecting, sampling and holding sequentially and separately for each of said frequencies the intensity of the radiation as provided after said latter radiation has traversed a path that contains said host gas and the particular gas;
- forming signal representations of the quotients of said intensities as measured pursuant to said measuring steps and separately for each said frequencies, said quotients each being the relative transmission for each of said frequencies;
- and
- processing the signal representations electrically to obtain a representation of the concentration of the particular gas in the host gas.
Dependencies are inferred from the claim text.