Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
168 words
An infrared two gas analyzer comprising a. a sample cell containing a sample of the gas to be analyzed, b. an infrared detector, c. a source of infrared radiation directed through said sample cell and onto said infrared detector, d. a rotating filter wheel having a pair of analytic filters, each having transmissive areas which pass radiation in an absorption region of a different gas whose presence is desired to be detected, and a pair of reference filters having transmissive areas interspersed between said analytic filters for passing radiation in a non-absorbing region of said pair of analytic filters, said filter wheel being positioned between said source and said infrared detector, e. two reference pick-ups for generating time reference signals in accordance with the position of said filter wheel, f. synchronous demodulator means coupled to said infrared detector and said reference pick-ups for rectifying and selecting the signal for the gas desired to be detected; and g. means for indicating the amount of the gas which is detected.
Claim 2
Dependent Claim
168 words
An infrared two gas analyzer comprising a. a sample cell containing a sample of the gas to be analyzed, b. an infrared detector, c. a source of infrared radiation directed through said sample cell and onto said infrared detector, d. a rotating filter wheel having a pair of analytic filters, each having transmissive areas which pass radiation in an absorption region of a different gas whose presence is desired to be detected, and a pair of reference filters having transmissive areas interspersed between said analytic filters for passing radiation in a non-absorbing region of said pair of analytic filters, said filter wheel being positioned between said source and said infrared detector, e. two reference pick-ups for generating time reference signals in accordance with the position of said filter wheel, f. synchronous demodulator means coupled to said infrared detector and said reference pick-ups for rectifying and selecting the signal for the gas desired to be detected; and g. means for indicating the amount of the gas which is detected.
Claim 3
Dependent Claim
21 words
The two-gas analyzers set forth in claim 1 wherein said two reference pick-ups are positioned in quadrature around said filter wheel.
Claim 4
Dependent Claim
32 words
The infrared two-gas analyzer set forth in claim 1 including compensation means for radiometrically balancing said analytic filter with its reference filter to provide no signal when no absorber gases are present.
Claim 5
Dependent Claim
29 words
The infrared two-gas analyzer set forth in claim 3 wherein said compensation means includes a masking means comprising an adjustable mask for trimming the transmissive areas of said filters.
Claim 6
Dependent Claim
33 words
The infrared two-gas analyzer set forth in claim 4 wherein said adjustable mask has arcuate end portions which project uniformly in the transmissive of said filters to prevent radiation chopping by said mask.
Claim 7
Dependent Claim
71 words
The infrared two-gas analyzer set forth in claim 1 in which said synchronous demodulator means comprises two synchronous demodulators, one for each gas with the output of the detector being coupled to each synchronous demodulator and the output from each of said reference pick-ups being applied to a different synchronous demodulator and separate meter means coupled to each synchronous demodulator for providing a simultaneous reading for the two gases being analyzed.
Claim 8
Dependent Claim
53 words
The two-gas analyzer set forth in claim 6 wherein said filters on said filter wheel and the reference pick-ups around said filter wheel are positioned in phase quadrature, and masking means are provided to trim the transmissive areas of said filters for providing a radiometric balance between the analytic and the reference filters.
Claim 9
Dependent Claim
54 words
The two-gas analyzer set forth in claim 1 wherein one said analytic filter passes radiation in a hydrocarbon absorption region on the order of 3.4 microns and the other analytic filter passes radiation in a carbon monoxide region on the order of 4.7 microns and said reference filters are clear for both these gases.