Patent US4008961A successfully refreshed from Google Patents.
US4008961A
Expired / Lapsed
US
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Monochromatic detection of plural rotational Raman spectra generated by multiple frequency excitation
Assignee: Honeywell International Inc
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Filing: 1975-04-21
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Granted: 1977-02-22
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Expires: 1995-04-21
Abstract
Abstract A method and apparatus for spectroscopic gas analysis are provided. Plural beams of monochromatic radiation are directed through gaseous material. A tuning mechanism adjusts the frequency difference between the radiation beams to equal substantially an odd integral submultiple of the frequency difference between adjacent spectral components of the periodic spectrum for a preselected constituent of the gaseous material. Radiation scattered by the gaseous material is received by a filtering mechanism adapted to transmit selectively a detectable signal composed of a single superimposed spectral component of the spectrum. The signal is received by a detecting means which indicates the intensity thereof.
Inventors
- 👤 Joseph J. Barrett
- 👤 Ernest D. Buff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:59
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/28; G01J3/44
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
169 words
Apparatus for spectroscopically analyzing gas comprising: a. radiation source means for generating a plurality of spatially superimposed beams of monochromatic radiation; b. tuning means for adjusting the frequency difference between radiation beams of adjacent frequencies to equal substantially an odd integral submultiple of the frequency difference between adjacent spectral components of the periodic spectrum for a preselected constituent of gaseous material; c. projecting means for directing said radiation beams through said gaseous material to produce scattered radiation, the scattered radiation produced by each of said radiation beams having spectral components periodic in frequency and the spectral components for said preselected constituent being superimposed to form, within the spectrum produced by combined scattering of said radiation beams, the periodic spectrum for said preselected constituent; d. filtering means adapted to receive said scattered radiation, for selectively transmitting a detectable signal composed of a single superimposed spectral component of said spectrum, whereby said detectable signal is derived from a plurality of spectral lines and has an intensity substantially equal to their sum.
Claim 2
Dependent Claim
169 words
Apparatus for spectroscopically analyzing gas comprising: a. radiation source means for generating a plurality of spatially superimposed beams of monochromatic radiation; b. tuning means for adjusting the frequency difference between radiation beams of adjacent frequencies to equal substantially an odd integral submultiple of the frequency difference between adjacent spectral components of the periodic spectrum for a preselected constituent of gaseous material; c. projecting means for directing said radiation beams through said gaseous material to produce scattered radiation, the scattered radiation produced by each of said radiation beams having spectral components periodic in frequency and the spectral components for said preselected constituent being superimposed to form, within the spectrum produced by combined scattering of said radiation beams, the periodic spectrum for said preselected constituent; d. filtering means adapted to receive said scattered radiation, for selectively transmitting a detectable signal composed of a single superimposed spectral component of said spectrum, whereby said detectable signal is derived from a plurality of spectral lines and has an intensity substantially equal to their sum.
Claim 3
Dependent Claim
34 words
Apparatus as recited in claim 1, wherein said filtering means has interference-producing means for providing a single transmission window centered on the frequency of one of said superimposed spectral components of said preselected constituent.
Claim 4
Dependent Claim
40 words
Apparatus as recited in claim 2 wherein said filtering means has associated therewith a frequency shifting means for displacing the frequencies of said radiation beams relative to the frequency of said transmission window is located half-way between adjacent radiation beams.
Claim 5
Dependent Claim
48 words
Apparatus as recited in claim 2 wherein said tuning means has associated therewith a frequency shifting means for displacing the frequencies of said radiation beams relative to the frequency of said transmission window so that the frequency of said transmission window is located half-way between adjacent radiation beams.
Claim 6
Dependent Claim
49 words
Apparatus as recited in claim 1 wherein said radiation source means comprises a dye laser including a dye cell containing a dye material, means for exciting said dye and a laser cavity comprised of an optical element and a partially transmitting output mirror for generating and transmitting laser radiation.
Claim 7
Dependent Claim
27 words
Apparatus as recited in claim 5 wherein said dye material emits radiation upon being excited, said radiation having frequencies within the transparency range of said gaseous material.
Claim 8
Dependent Claim
16 words
Apparatus as recited in claim 1 including detecting means for indicating the intensity of said signal.
Claim 9
Dependent Claim
44 words
Apparatus as recited in claim 7 including modulating means for modulating the phase difference between interfering rays of said radiation so as to vary the intensity of said superimposed spectral component, the modulating range being no greater than the frequency spacing between adjacent orders.
Claim 10
Dependent Claim
24 words
Apparatus as recited in claim 8 wherein said modulating means has a modulating range of about 1/2 the frequency difference between adjacent radiation beams.
Claim 11
Dependent Claim
24 words
Apparatus as recited in claim 8 wherein said modulating means is a piezoelectric cylinder and said detecting means is a phase sensitive detection system.
Claim 12
Dependent Claim
38 words
Apparatus as recited in claim 1 wherein said radiation source means is provided with means for projecting radiation having a line width and frequency stability about equal to or less than the instrumental width of said filtering means.
Claim 13
Dependent Claim
17 words
Apparatus as recited in claim 5 wherein said means for exciting said dye is a pulsed laser.
Claim 14
Dependent Claim
62 words
Apparatus as recited in claim 12 wherein said laser is associated with a time gated electronic detection system having (1) means for measuring the time interval required to send a pulse from said laser into a sample of said gaseous material and receive a return signal caused by light scattered therein and (2) means for measuring the amplitude of said return signal.
Claim 15
Dependent Claim
25 words
Apparatus as recited in claim 1 wherein said periodic spectrum is the spectrum produced by Raman scattering of a minor constituent of a gaseous material.
Claim 16
Dependent Claim
12 words
Apparatus as recited in claim 14 wherein said gaseous material is air.
Claim 17
Dependent Claim
32 words
Apparatus as recited in claim 5 wherein said radiation source means includes a multiple frequency beam generating means for separating said radiation into a plurality of spatially superimposed beams of monochromatic radiation.
Claim 18
Dependent Claim
18 words
Apparatus as recited in claim 16 wherein said multiple frequency beam generating means is a Fabry Perot interferometer.
Claim 19
Dependent Claim
94 words
Apparatus as recited in claim 10 including means for applying to said cylinder a voltage having a square wave form, the limits of said voltage being adjusted so that the intensity of said superimposed spectral component alternates between its maximum and minimum values, means for determining for each cycle of said voltage the difference in photon count between said maximum and minimum values of said component to produce a signal count, and means for accumulating said signal count for a preselected period of time over a preselected number of cycles of said square wave.
Claim 20
Dependent Claim
27 words
Apparatus as recited in claim 18 including means for varying the preselected time period and the preselected number of cycles inversely with the intensity of said component.
Claim 21
Dependent Claim
16 words
Apparatus as recited in claim 10 wherein said phase sensitive detection system is a lock-in amplifier.
Claim 22
Dependent Claim
24 words
Apparatus as recited in claim 8 wherein said modulating means is a piezoelectric cylinder and said synchronous detection means is a photon counting system.
Claim 23
Independent Claim
138 words
A method for spectroscopically analysing gas comprising the steps of: a. generating a plurality of spatially superimposed beams of monochromatic radiation; b. adjusting the frequency differency between radiation beams of adjacent frequencies to equal substantially an odd integral sub-multiple of the frequency difference between adjacent spectral components of the periodic spectrum for preselected constituent of gaseous material; c. directing said radiation beams through said gaseous material to produce scattered radiation, the scattered radiation produced by each of said radiation beams having spectral components periodic in frequency and the spectral components for said preselected constituent being superimposed to form, within the spectrum produced by combined scattering of said radiation beams, the periodic spectrum for said preselected constituent; and d. filtering the scattered radiation to selectively transmit a detectable signal composed of a single superimposed spectral component of the spectrum.
Claim 24
Independent Claim
138 words
A method for spectroscopically analysing gas comprising the steps of: a. generating a plurality of spatially superimposed beams of monochromatic radiation; b. adjusting the frequency differency between radiation beams of adjacent frequencies to equal substantially an odd integral sub-multiple of the frequency difference between adjacent spectral components of the periodic spectrum for preselected constituent of gaseous material; c. directing said radiation beams through said gaseous material to produce scattered radiation, the scattered radiation produced by each of said radiation beams having spectral components periodic in frequency and the spectral components for said preselected constituent being superimposed to form, within the spectrum produced by combined scattering of said radiation beams, the periodic spectrum for said preselected constituent; and d. filtering the scattered radiation to selectively transmit a detectable signal composed of a single superimposed spectral component of the spectrum.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-02-22 | 1980-08-23 | 1981-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-22 | 1984-08-23 | 1985-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-22 | 1988-08-23 | 1989-02-22 | $7700.00 | Window Closed / Lapsed |