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US3756726A
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Spectral analysis utilizing a beam-switching optical system
Assignee: Barnes Engineering Co
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Filing: 1971-03-29
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Granted: 1973-09-04
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Expires: 1991-03-29
Abstract
Abstract A beam-switching optical system receives radiation from a source which is passed through a sample cell containing matter to be analyzed. The system is comprised of four small fixed mirrors, a narrow band pass interference filter, and a mirrored radiation chopper having an odd number of alternating reflecting and open sectors. The small fixed mirrors are arranged in cooperating reflecting pairs with the interference filter and chopper positioned therebetween, such that the rotation of the radiation chopper alternately directs the radiation through the interference filter at two different angles of incidence. This switching of the incidence angle shifts the band pass of the interference filter to provide radiation in two spectral regions. The output of the beam switching optical system is applied to a detector producing an AC signal which is the measure of the slope of the transmission curve of the filter. The amplitude of the signal which is synchronously demodulated constitutes an indication of the magnitude of the constituent of the sample being analyzed.
Inventors
- 👤 R Astheimer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:02
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/314
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
252 words
A beam switching optical system for spectral analysis of a sample in two spectral bands, comprising a. a sample containing matter to be analyzed, b. a radiation source for directing a beam of radiation through said sample, c. means defining a first optical path of predetermined path length for receiving said beam of radiation from said sample having a first and a second fixed mirror which are spaced in optical alignment, d. means defining a second optical path having the same predetermined path length as said first optical path for receiving said beam of radiation from said sample having a third and a fourth fixed mirror which are spaced in optical alignment, e. a single narrow band pass filter means positioned to intersect both said first and said second optical paths each of which provides a different angle of incidence for radiation from said sample to said filter means, f. beam switching means positioned between said first and second fixed mirrors and said third and fourth fixed mirrors for alternately optically switching said beam of radiation from said sample to said first and second optical paths whereby the angle of incidence of said beam of radiation applied to said filter means is changed to produce therefrom radiation in two spectral regions, and g. radiation detector means positioned to receive radiation in two spectral regions at the same angle from said first and second optical paths for producing signals corresponding to the radiation passed by said filter means in said two spectral regions.
Claim 2
Dependent Claim
252 words
A beam switching optical system for spectral analysis of a sample in two spectral bands, comprising a. a sample containing matter to be analyzed, b. a radiation source for directing a beam of radiation through said sample, c. means defining a first optical path of predetermined path length for receiving said beam of radiation from said sample having a first and a second fixed mirror which are spaced in optical alignment, d. means defining a second optical path having the same predetermined path length as said first optical path for receiving said beam of radiation from said sample having a third and a fourth fixed mirror which are spaced in optical alignment, e. a single narrow band pass filter means positioned to intersect both said first and said second optical paths each of which provides a different angle of incidence for radiation from said sample to said filter means, f. beam switching means positioned between said first and second fixed mirrors and said third and fourth fixed mirrors for alternately optically switching said beam of radiation from said sample to said first and second optical paths whereby the angle of incidence of said beam of radiation applied to said filter means is changed to produce therefrom radiation in two spectral regions, and g. radiation detector means positioned to receive radiation in two spectral regions at the same angle from said first and second optical paths for producing signals corresponding to the radiation passed by said filter means in said two spectral regions.
Claim 3
Dependent Claim
82 words
The beam switching optical system set forth in claim 1 wherein said beam switching means comprises a mirrored radiation chopper having an odd number of alternating reflecting and open sectors with the beam of radiation from said sample being directed thereto whereby said means defining said first and second optical paths including said chopper provide the same number of reflections, the same path length and the same angle of incidence on said radiation detector means from said source to said detector means.
Claim 4
Dependent Claim
56 words
The beam switching optical system set forth in claim 2 includiNg a reference signal generator coupled to said radiation chopper, a synchronous demodulator, means coupling said radiation detector means and said reference signal generator to said demodulator for producing an output from said demodulator having an amplitude corresponding to a constituent of the sample being analyzed.
Claim 5
Dependent Claim
62 words
The beam switching optical system set forth in claim 1 including means for adjusting the position of said filter means whereby separation of spectral bands of said filter means being adjusted by tilting said filter means in one plane and the band pass of said filter means being adjusted by tilting said filter means in another plane away from said one plane.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |