US3825344A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for analysing a substance by atomic absorption with background correction
Assignee: Commissariat à l'Énergie Atomique et Aux Énergies Alternatives
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Filing: 1972-09-06
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Granted: 1974-07-23
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Expires: 1992-09-06
Abstract
Abstract The invention relates to a device for analysing a substance by atomic absorption with background correction in which the substance is vaporised in a chamber and light beams are transmitted through the vapour from two light sources, one of which has a band wavelength spectrum while the other has a line spectrum, one of the lines being centred at the atomic absorption wavelength. A monochromator is centred at the atomic absorption wavelength for alternately receiving the light beams and a photoelectric detector is disposed at the monochromator output for supplying electric signals. According to the invention electric modulators act on the electric supplies to the light sources for modulating the light beams substantially in the form of square waves of equal duration. The modulators are synchronised with one another and with comparison means which compares the electric signals supplied by the detector. A stationary semi-transparent mirror is disposed in the path of the two beams so that the beams follow the same path from the mirror to the monochromator.
Inventors
- 👤 R Bonne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:35
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/3103
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
253 words
A device for analysing a substance by atomic absorption with background correction, comprising: means for vaporising the substance in a chamber, two light sources, one having a a band wavelength spectrum and the other a line spectrum, one of the spectrum lines being centered at the atomic absorption wavelength, a monochromator centered at the aforementioned wavelength and alternatively receiving the light beams transmitted by the aforementioned two sources after the beams have travelled through the vapour, a photoelectric detector disposed at the monochromator output and means for comparing the electric signals supplied by the detector, said device being characterised by a stationary semi-transparent mirror disposed in the path of the two beams so that the beams follow the same path from the mirror to the monochromator, electric modulators each acting on the electric supply to one of the aforementioned sources and modulating the light beams substantially in the form of square waves of equal duration in such a manner that the leading edge of a square wave for one of the two aforementioned light beams corresponds to the trailing edge of the square wave of the other light beam, means for synchronizing the modulators with one another and with the aforementioned comparison means, means included in said comparison means for changing the origin of the amplitude of the square-wave electric signals supplied by the detector, the new origin being taken as the average value of tHe amplitudes in the absence of atomic absorption by the vaporised substance, and an a.c. - d.c. converter.
Claim 2
Independent Claim
253 words
A device for analysing a substance by atomic absorption with background correction, comprising: means for vaporising the substance in a chamber, two light sources, one having a a band wavelength spectrum and the other a line spectrum, one of the spectrum lines being centered at the atomic absorption wavelength, a monochromator centered at the aforementioned wavelength and alternatively receiving the light beams transmitted by the aforementioned two sources after the beams have travelled through the vapour, a photoelectric detector disposed at the monochromator output and means for comparing the electric signals supplied by the detector, said device being characterised by a stationary semi-transparent mirror disposed in the path of the two beams so that the beams follow the same path from the mirror to the monochromator, electric modulators each acting on the electric supply to one of the aforementioned sources and modulating the light beams substantially in the form of square waves of equal duration in such a manner that the leading edge of a square wave for one of the two aforementioned light beams corresponds to the trailing edge of the square wave of the other light beam, means for synchronizing the modulators with one another and with the aforementioned comparison means, means included in said comparison means for changing the origin of the amplitude of the square-wave electric signals supplied by the detector, the new origin being taken as the average value of tHe amplitudes in the absence of atomic absorption by the vaporised substance, and an a.c. - d.c. converter.
Claim 3
Dependent Claim
20 words
A device according to claim 1, characterised in that the light source having a line spectrum is a hollow cathode.
Claim 4
Dependent Claim
20 words
A device according to claim 1, characterised in that the light source having a band spectrum is a deuterium source.
Claim 5
Dependent Claim
15 words
A device according to claim 1, characterised in that the photoelectric detector is a photomultiplier.
Claim 6
Dependent Claim
20 words
A device according to claim 1 characterised in that the light source having a band spectrum is a vacuum source.
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) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |