US3819945A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Spectrometers
Assignee: Environmental Data Corp
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Filing: 1973-06-25
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Granted: 1974-06-25
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Expires: 1993-06-25
Abstract
Abstract The present disclosure relates to spectrometry. A method is disclosed for detecting nitric oxide (NO) without first converting it to nitrogen dioxide (NO2) by determining the intensity of a spectral signature in the range between 2,259 and 2,269 Angstroms. Apparatus is provided which, in one form, utilizes an output shutter arrangement having a plurality of reciprocating vanes operated at mutually exclusive frequencies for passing regions of absorption radiation and continuum radiation. Circuit means is provided for distinguishing the signals derived at the various frequencies to determine the relative amount of particular material in a sample. In another form of the invention, an output chopper is provided having at least three slit apertures, the center aperture being adapted to pass only radiation at an absorptive wavelength and the two outer apertures being adapted to pass radiation in the continuum. A vane is adapted to reciprocate between a first position wherein the chopper passes only radiation through the center aperture and a second position wherein the chopper passes only radiation through the two outer apertures. The area of each of the two outer apertures is preferably one-half the area of the center aperture. A detector viewing radiation passed by the chopper will average the radiation received from the two outer apertures. In yet another aspect of the invention, a window assembly is provided so that the spectrometer may be used as a a stack monitor, the window assembly having a slidable window which may be removed for cleaning purposes.
Inventors
- 👤 D Egan
- 👤 G Holstrom
- 👤 D Port
- 👤 R Howard
- 👤 H Lord
- 👤 R Stevens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:31
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/33; G01J; G01J3/00; G01J3/28; G01J3/457; G01J2003/2866
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
403 words
In a spectrometric apparatus having an entrance slit for passage of light radiation, means for dispersing the radiation passed through the entrance slit to form a spectrum of the radiation having a range of wave lengths, means forming images of the entrance slit at positions corresponding to component wave lengths of the spectrum, exit slit means at said positions, said exit slit means comprising a first, a second and a third slit aperture, said first slit aperture being so disposed and arranged with respect to said dispersion means as to pass radiation at a first predetermined wave length associated with an absorption frequency of a particular material, said second slit aperture being so disposed and arranged with respect to said dispersion means as to pass radiation at a second predetermined wave length associated with a continuum frequency relative to said particular material, said second wave length being shorter than said first wave length, and said third slit aperture being so disposed and arranged with respect to said dispersion means as to pass radiation at a third predetermined wave length associated with a continuum frequency relative to said particular material, said third wave length being longer than said first wave length, detecting means indicating the intensity of radiAtion passing through the exit slit means, vane means reciprocable between first and second positions, and so disposed and arranged with respect to said slit apertures that when said vane means is in the first position it passes radiation from said first slit aperture while blocking radiation from said second and third slit apertures, and when in said second position said vane means passes radiation from said second and third slit apertures while blocking radiation from said first slit aperture, the improvement wherein said vane means comprises a plate having a plate aperture, the size of said plate and the location of said plate aperture being such that when said vane means is in its first position the plate aperture is aligned with said first slit aperture and the plate blocks radiation passing through said second and third slit apertures, and when said vane means is in its second position the plate aperture is aligned with said second slit aperture and the plate blocks radiation passing through said first slit aperture and said third slit aperture is beyond the edges of said plate, so that said plate does not block radiation passing through said third slit aperture.
Claim 2
Dependent Claim
27 words
Apparatus according to claim 2 wherein the combined area of said second and third slit apertures is substantially equal to the area of said first slit aperture.
Claim 3
Dependent Claim
23 words
Apparatus according to claim 3 further including reciprocating means connected to said vane means for reciprocating said vane means at a predetermined frequency.
Claim 4
Dependent Claim
80 words
Apparatus according to claim 4 wherein said reciprocating means comprises a substantially U-shaped tuned member the U of which has opposing legs, and said member having a natural frequency of vibration, said member having a center leg connected to said vane, first and second coil means, the opposing legs of said U-shaped member forming cores for said first and second coil means, respectively, whereby upon vibration of said member, a current is induced into said coils at said predetermined frequency.
Claim 5
Dependent Claim
27 words
Apparatus according to claim 1 wherein the combined area of said second and third slit apertures is substantially equal to the area of said first slit aperture.
Claim 6
Dependent Claim
25 words
Apparatus according to claim 1 further including reciprocating means connected to said first vane means for reciprocating said first vane means at a predetermined frequency.
Claim 7
Dependent Claim
61 words
Apparatus according to claim 1 wherein said first slit aperture is positioned to pass radiation having a wavelength lambda , one of said second and third slit apertures being positioned to pass radiation having a wavelength lambda + lambda 1, and the other of said second and third slit apertures is positioned to pass radiation having a wavelength lambda -lambda 2.
Claim 8
Dependent Claim
53 words
Apparatus according to claim 8 wherein lambda is in the range between 2,259 and 2,269 Angstroms and lambda 1 and lambda 2 are in the range of about 5 to 50 Angstroms, and lambda + lambda 1 and lambda - lambda 2 are at a wavelength of an absorption frequency of sulfur dioxide.
Claim 9
Dependent Claim
50 words
Apparatus according to claim 8 wherein the intensity of radiation at lambda - lambda 1 is below the expected intensity of background radiation at lambda by the same amount that the intensity of radiation at lambda + lambda 2 is above the expected intensity of background radiation at lambda .
Claim 10
Dependent Claim
55 words
Apparatus according to claim 4 including an additional vane means reciprocable between first and second positions and disposed and arranged with respect to said entrance slit so that when in the last-mentioned first position radiation is passed through said entrance slit and when in said last-mentioned second position radiation is blocked through said entrance slit.
Claim 11
Dependent Claim
32 words
Apparatus according to claim 11 in which the frequencies of reciprocation of said additional vane means and of the vane means comprising the plate having an aperture, are different from each other.
Claim 12
Dependent Claim
290 words
In a spectrometric apparatus haviNg an entrance slit for passage of light radiation, means for dispersing the radiation passed through the entrance slit to form a spectrum of the radiation having a range of wave lengths, means forming images of the entrance slit at positions corresponding to component wave lengths of the spectrum, exit slit means at said positions, said exit slit means comprising a first and a second slit aperture, said first slit aperture being so disposed and arranged with respect to said dispersion means as to pass radiation at a first predetermined wave length associated with an absorption frequency of a particular material, said second slit aperture being so disposed and arranged with respect to said dispersion means as to pass radiation at a second predetermined wave length associated with a continuum frequency relative to said particular material, and detecting means indicating the intensity of radiation passing through the exit slit means, a first vane reciprocable between first and second positions, and so disposed and arranged with respect to said slit apertures that when in said first position, said vane passes radiation from said first slit aperture while blocking radiation from said second slit aperture, and when in said second position said first vane passes radiation from said second slit aperture while blocking radiation from said first slit aperture, and the improvement comprising: a second vane reciprocable between first and second positions, and so disposed and arranged with respect to said entrance slit that when said second vane is in its first position it passes radiation through said entrance slit, and when in its second position it blocks radiation through said entrance slit, the frequencies of reciprocation of the first and second vanes being different from each other.
Claim 13
Dependent Claim
21 words
Apparatus according to claim 13 in which said frequencies of reciprocation of the first and second vanes have different fundamental frequencies.
Claim 14
Dependent Claim
254 words
In the method of measuring the quantity of nitric oxide in a sample of gas containing sulfur dioxide, the nitric oxide having a radiation intensity spectrum over a range of wavelengths comprising continuum and a number of spaced absorption peaks, a first of said absorption peaks being at 2,259 Angstroms and a second of said absorption peaks next adjacent said first peak being between 2,259 and 2,269 Angstroms, and the sulfur dioxide having a radiation intensity spectrum over the same range of wavelengths comprising continuum and a number of spaced absorption peaks, a first of the sulfur dioxide absorption peaks being at a wavelength coinciding with that of said first nitric oxide absorption peak and merging into a second sulfur dioxide absorption peak next adjacent its said first absorption peak at a higher wavelength than 2,269 Angstroms and a third sulfur dioxide absorption peak next adjacent its first absorption peak at a wavelength lower than 2,259 Angstroms, said method comprising displaying a spectrum of the sample and measuring the radiation intensities in the vicinity of an absorption wavelength and in the vicinity of a continuum wavelength and comparing the said intensities, the improvement comprising: measuring the radiation intensity at one of said nitric oxide absorption peaks at which there is significant absorption of sulfur dioxide and also measuring the radiation intensity at another wavelength at which the absorption of sulfur dioxide is substantially the same as at said one of said nitric oxide absorption peaks and comparing the intensities of the two last-mentioned measurements.
Claim 15
Dependent Claim
42 words
Method according to claim 15 in which the nitric oxide is measured at its second peak and the sulfur dioxide is measured at a wavelength where the higher wavelength side of at least one of its said peaks merges into the continuum.
Claim 16
Dependent Claim
19 words
Method according to claim 16 in which said one peak of the sulfur dioxide is the higher wavelength peak.
Claim 17
Dependent Claim
29 words
Method according to claim 17 in which the sulfur dioxide is also meaSured at the wavelength where the higher wavelength side of its third peak merges into the continuum.
Claim 18
Dependent Claim
29 words
Method according to claim 15 in which the nitric oxide is measured at its said first peak and the sulfur dioxide is measured at one of its said peaks.
Claim 19
Dependent Claim
15 words
Method according to claim 19 in which said one peak is the higher wavelength peak.
Claim 20
Dependent Claim
17 words
Method according to claim 19 in which the sulfur dioxide is measured at both its said peaks.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |