US3711708A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rapid scan identifier for use in infrared absorption spectroscopy
Assignee: Optical Coating Laboratory Inc
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Filing: 1971-02-25
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Granted: 1973-01-16
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Expires: 1991-02-25
Abstract
Abstract A rapid scan spectrum identifier fur use in identifying infrared spectrum of the output of a gas chromatograph to identify its absorption characteristics and includes an infrared source and beam splitter, a double beam chopper for alternately sending the infrared beam through a sample or reference gas cell mounted in a suitable furnace, the output of which is recombined and analyzed by a monochromator having a narrow output passband of energy detected by a rapid response detector, the output of which is processed by suitable electronic circuitry to provide a readout. The monochromator is of the scanning type in which a grating is synchronously scanned with a circular variable filter so that the first order output of the grating is selectively passed and higher orders rejected by the filter. The sample and reference gas cell furnace assembly utilizes specially constructed sample and reference gas cells symmetrically mounted in a furnace arrangement for maintaining input gas streams at equal temperatures within each cell and above the temperature of condensation of the sample under investigation. The beam chopper contains associated photoelectronics for physically determining the location of a chopping blade to thereby provide gating signals for indicating the presence at the detector of a sample, reference, or a background signals. These grating signals are used in sample and hold circuits to convert an essentially digitally sampled output into a relatively smooth continuous curve indicative of the absorption of the sample so that the readout represents the sample absorption characteristics corrected for reference for the carrier gas and background effects. The instrument is designed to operate with scan rates of approximately 6 and 30 seconds.
Inventors
- 👤 D Geiger
- 👤 S Dolin
- 👤 A Folch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:53
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/02; G01J3/0202; G01J3/0205; G01J3/0232; G01J3/04; G01J3/06; G01J3/12; G01J3/26; G01J3/28; G01J3/2889; G01J3/42; G01N; G01N30/00; G01N30/02; G01N30/62; G01N30/74
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
487 words
In a rapid scanning infrared spectrometer for analyzing the output of a gas chromatograph in which samples are vaporized into a carrier gas stream and separated into fractions by said gas chromatograph, an elongated light reflecting tube sealed at each end thereof, means connected to said tube for supplying the gas output of said chromatograph to said tube, means for heating said tube to a temperature above the condensation point of the material vaporized in said stream, a second elongated light reflecting tube sealed at each end and identical in construction to said first tube, means for delivering a carrier gas stream to said second elongated tube, means for symmetrically mounting and heating said tubes in a furnace, an infrared source, means for dividing a portion of the output of said source into separate beams and for focusing said beams into an input end of each of said light tubes, a monochromator for receiving the output of said sample and refereNce gas cells and for selecting and transmitting a narrow band selected portion of the infrared energy band, means for receiving the light beam emitted from the other end of each of said tubes and for recombining said beams into a single beam and focusing the same upon the input of said monochromator, a detector for receiving the output of said monochromator said detector having a broad bandwidth and a rapid response and generating an output to thereby generate output signals in electrical output signals proportional to the strength of energy falling upon said detector, chopper means including a blade mounted in the paths of said sample and reference beams before the same pass through said light tubes said blade being constructed to have portions for selectively and alternately blocking either the sample light path or the reference light path and further having portions for blocking both light paths and thereby permit the detector to generate signals S+B, R+B and B corresponding respectively to reception of light energy S+B passed through the sample cell, of light energy R+B passed through the reference cell or of background light energy B which is residual to each cell so that said sample and reference beams are chopped at a predetermined frequency to give an alternating signal while said background signal is not chopped, means for developing electric signals corresponding to the physical movement of said chopper means for defining sampling pulses, (R), (B) coincident with a predetermined interval during which corresponding one of said detected signals, R, B is present at said detector, means responsive to said sampling pulses for sampling the S, R, B signals during the coincidence of the respective pulse and for holding the last value obtained to develop signals, R, and B which represent the value of the signals S, R, and B during the intervals (S), (R) and (B) respectively, means for computing an approximation to the ratio S/R compensated for the background signal B.
Claim 2
Dependent Claim
487 words
In a rapid scanning infrared spectrometer for analyzing the output of a gas chromatograph in which samples are vaporized into a carrier gas stream and separated into fractions by said gas chromatograph, an elongated light reflecting tube sealed at each end thereof, means connected to said tube for supplying the gas output of said chromatograph to said tube, means for heating said tube to a temperature above the condensation point of the material vaporized in said stream, a second elongated light reflecting tube sealed at each end and identical in construction to said first tube, means for delivering a carrier gas stream to said second elongated tube, means for symmetrically mounting and heating said tubes in a furnace, an infrared source, means for dividing a portion of the output of said source into separate beams and for focusing said beams into an input end of each of said light tubes, a monochromator for receiving the output of said sample and refereNce gas cells and for selecting and transmitting a narrow band selected portion of the infrared energy band, means for receiving the light beam emitted from the other end of each of said tubes and for recombining said beams into a single beam and focusing the same upon the input of said monochromator, a detector for receiving the output of said monochromator said detector having a broad bandwidth and a rapid response and generating an output to thereby generate output signals in electrical output signals proportional to the strength of energy falling upon said detector, chopper means including a blade mounted in the paths of said sample and reference beams before the same pass through said light tubes said blade being constructed to have portions for selectively and alternately blocking either the sample light path or the reference light path and further having portions for blocking both light paths and thereby permit the detector to generate signals S+B, R+B and B corresponding respectively to reception of light energy S+B passed through the sample cell, of light energy R+B passed through the reference cell or of background light energy B which is residual to each cell so that said sample and reference beams are chopped at a predetermined frequency to give an alternating signal while said background signal is not chopped, means for developing electric signals corresponding to the physical movement of said chopper means for defining sampling pulses, (R), (B) coincident with a predetermined interval during which corresponding one of said detected signals, R, B is present at said detector, means responsive to said sampling pulses for sampling the S, R, B signals during the coincidence of the respective pulse and for holding the last value obtained to develop signals, R, and B which represent the value of the signals S, R, and B during the intervals (S), (R) and (B) respectively, means for computing an approximation to the ratio S/R compensated for the background signal B.
Claim 3
Dependent Claim
135 words
A rapid scan spectrometer as in claim 1 in which said monochromator includes a grating, means for selectively transferring the selected portion of the first order spectrum of said grating, a circular variable long pass filter having a cut-on frequency lying between said first and second order outputs of said grating for passing long wavelengths and rejecting short wavelengths received from said grating and having a characteristic such that said cut-on frequency continuously varies as a function of a lineal distance along said filter, means mounting said filter and said grating and ganging together for synchronous movement whereby said cut-on frequency is shifted so to remain between said first and second orders of the grating as the grating operates to scan the infrared spectrum and to define a narrow bandpass output beam from said monochromator.
Claim 4
Dependent Claim
28 words
Apparatus as in claim 2 in which said means for mounting said grating and said circular variable filter are operative over a period of less than 10 seconds.
Claim 5
Dependent Claim
22 words
Apparatus as in claim 2 in which said driving means operate said grating and filter over a period of about 30 seconds.
Claim 6
Dependent Claim
43 words
A spectrometer as in claim 1 in which each of said source optics, monochromator and detector are arranged on independent subframes as integral assembles, and in which a base plate serves as a frame for mounting each of said subframes for interchangeable assembly.
Claim 7
Dependent Claim
96 words
A spectrometer as in claim 5 in which said frame plate is provided with a plurality of recesses having depths precisely developed with respect to each other in accordance with the accuracy of the bed of a machine for forming the same whereby said frame plate may be non-flat precision bearing disposed in each of said frame recesses, means formed in each assembly subframe and corresponding to lateral positioning of said bearings to form a kinematic mounting thErefore, means for yieldably urging each subframe into positional contact on its respective bearings to precisely support the same.
Claim 8
Dependent Claim
22 words
An infrared spectrometer as in claim 6 in which the associated optical elements on each subframe are prealigned for precise interchangeable assembly.
Claim 9
Dependent Claim
81 words
An infrared spectrometer as in claim 1 in which said chopper means is a disc mounted such that one portion is in the sample beam light path and another portion is in the reference beam light path, means for rotating said disc, said disc having blades thereon arranged to alternately pass either the sample light beam or the reference light beam, and further having portions for blocking both beams to thereby generate said S, R and B signals at said detector.
Claim 10
Dependent Claim
43 words
An infrared spectrometer as in claim 8 in which said means for developing electrical signals corresponding to physical movement of chopper includes a first photocell circuit for sensing the position of said disc while one of said sample or reference beams is passed.
Claim 11
Dependent Claim
50 words
An infrared spectrometer as in claim 8 in which said means for developing electrical signal corresponding to chopper position during blanking of both sample and reference beams includes second photocell circuit, apertures carried on said disc and aligned for passing light to indicate when said beams are to be blanked.
Claim 12
Dependent Claim
198 words
A spectrometer as in claim 1 in which said furnaces consists of and including assembly, a framework including a base, a furnace element, said a furnace element made of thermally conductive material insulator support means for mounting said furnace element in upstanding relation on said base, said furnace element being integral casting having spaced hollow cylindrical sections forming passageways therethrough a web interconnecting said cylindrical sections to form a symmetric structure, a heater symmetrically mounted on side of said web, a sample cell disposed on one tubular section, a reference cell disposed in the other tubular section, means interconnecting an input of said sample cell through a source to the output of a gas chromatograph means connecting the input to said reference cell to a source of carrier gas identical to that used in said gas chromatograph, a housing connected to said base plate and enclosing said furnace element, sample and reference cells means interconnecting the ends of said sample and reference cells to said housing to suspend the same within each respective cylindrical section without making physical contact therewith and a thermal insulated packing disposed to fill the space surrounding said furnace element and within said housing.
Claim 13
Dependent Claim
182 words
An infrared spectrometer as in claim 11 in which said sample cell and reference cell are identically constructed and each include an elongate tubular member having a passageway therethrough said passageway being defined by an interiorly facing wall having a highly reflective coating thereon to a radiation and infrared portion of the spectrum the ends of said tubular member terminating in substantially parallel flat planes, a pair of end plates each of said end plates having a recess therein carrying an o-ring for sealing engagements with a respective end of said tubular member said end plates further extending laterally away from said tubular member a sufficient distance to permit exterior interconnection of said end plates tensioning means interconnected between said end plates for applying slight tension to maintain said end plates in sealing engagement with said tubular member said tensioning means being symmetrically distributed about each of said end plates and having a thermal coefficient of expansion substantially identical to that of said tubular member whereby heating of the assembly does not cause any substantial thermal strain to develop in said part.
Claim 14
Dependent Claim
65 words
A cell construction as in the claim 12 further including an end cap having an aperture therein means for securing said end cap to said end plate an o-ring seal formed in the outer wall of said end pLate and a window disposed between said window retaining cap and said end plate and means for urging said window to into engagement with said second o-ring.
Claim 15
Dependent Claim
177 words
An infrared spectrometer as in claim 1 in which said sample and reference cell each comprises an elongate tubular member having a passageway therethrough said passageway being defined by an interiorly facing wall having a highly reflective coating thereon to a radiation and infrared portion of the spectrum the ends of said tubular member terminating in substantially parallel flat planes, a pair of end plates each of said end plates having a recess therein carrying an o-ring for sealing engagements with a respective end of said tubular member said end plates further extending laterally away from said tubular member a sufficient distance to permit exterior interconnection of said end plates tensioning means interconnected between said end plates for applying slight tension to maintain said end plates in sealing engagement with said tubular member said tensioning means being symmetrically distributed about each of said end plates and having a thermal coefficient of expansion substantially identical to that of said tubular member whereby heating of the assembly does not cause any substantial thermal strain to develop in said part.
Claim 16
Dependent Claim
64 words
A cell construction as in claim 14 further including an end cap having an aperture therein means for securing said end cap to said end plate an o-ring seal formed in the outer wall of said end plate and a window disposed between said window retaining cap and said end plate and means for urging said window into sealing engagement with said second o-ring.
Claim 17
Dependent Claim
39 words
A spectrometer as in claim 1, further including means for disabling all circuits to hold the last values obtained just before entering the 4.2 Mu CO2 absorption region and maintaining these values until the scan has passed this region.
Claim 18
Dependent Claim
192 words
A sample or reference cell adapted for use in infrared spectrometer for passing the output of a gas chromatograph therefor for spectral absorption analysis comprising an elongate tubular member of optical grade glass having a passageway therethrough, said passageway being defined by an interiorly facing wall having a highly reflective coating thereon to a radiation and infrared portion of the spectrum, the ends of said tubular member terminating in substantially parallel flat planes, a pair of end plates each of said end plates having a recess therein carrying an O-ring for sealing engagements with a respective end of said tubular member, said end plates further extending laterally away from said tubular member a sufficient distance to permit exterior interconnection of said end plates, metal rod tensioning means interconnected between said end plates for applying slight tension to maintain said end plates in sealing engagement with said tubular member said tensioning means being symmetrically distributed about each of said end plates and having a thermal coefficient of expansion substantially identical to that of said tubular member whereby heating of the assembly does not cause any substantial thermal strain to develop in said part.
Claim 19
Dependent Claim
192 words
A sample or reference cell adapted for use in infrared spectrometer for passing the output of a gas chromatograph therefor for spectral absorption analysis comprising an elongate tubular member of optical grade glass having a passageway therethrough, said passageway being defined by an interiorly facing wall having a highly reflective coating thereon to a radiation and infrared portion of the spectrum, the ends of said tubular member terminating in substantially parallel flat planes, a pair of end plates each of said end plates having a recess therein carrying an O-ring for sealing engagements with a respective end of said tubular member, said end plates further extending laterally away from said tubular member a sufficient distance to permit exterior interconnection of said end plates, metal rod tensioning means interconnected between said end plates for applying slight tension to maintain said end plates in sealing engagement with said tubular member said tensioning means being symmetrically distributed about each of said end plates and having a thermal coefficient of expansion substantially identical to that of said tubular member whereby heating of the assembly does not cause any substantial thermal strain to develop in said part.
Claim 20
Dependent Claim
63 words
A cell construction as in Claim 17 further including an end cap having an aperture therein, means for securing said end cap to said end plate, an O-ring seal formed in the outer wall of said end plate, a window disposed between said window retaining cap and said end plate, and means for urging said window into sealing engagement with said second O-ring.
Claim 21
Dependent Claim
83 words
A sample or reference cell as in Claim 17 in which said tubular member is constructed of four symmetrically disposed elements of optical grade glass, each having an interior coating and assembled to form an overlapping pattern in which straight tubular passageway is formed having a square cross-section, the interfaces between segments being surface roughened, bevels formed at the outer edge of each interface to form glue line troughs and a chemically inert, high temperaTure, non-porous glue line run continuously down each trough.
Claim 22
Dependent Claim
191 words
A sample and reference gas cell furnace assembly, a framework including a base a furnace element, a furnace element made up of thermally conductive material, insulator support means for mounting said furnace element in upstanding relation on said base said furnace element being integral casting having spaced hollow cylindrical sections forming passageways therethrough, a web interconnecting said cylindrical sections to form a symmetric structure, a heater symmetrically mounted on side of said web, a sample cell disposed in one tubular section, a reference cell disposed in the other tubular section, means interconnecting an input of said sample cell through a source to the output of a gas chromatograph means connecting the input to said reference cell to a source of carrier gas identical to that used in said gas chromatograph, a housing connected to said base plate and enclosing said furnace element, sample and reference cells, means interconnecting the ends of said sample and reference cells to said housing to suspend the same within each respective cylindrical section without making physical contact therewith, and a thermal insulated packing disposed to fill the space surrounding said furnace element and within said housing.
Claim 23
Dependent Claim
191 words
A sample and reference gas cell furnace assembly, a framework including a base a furnace element, a furnace element made up of thermally conductive material, insulator support means for mounting said furnace element in upstanding relation on said base said furnace element being integral casting having spaced hollow cylindrical sections forming passageways therethrough, a web interconnecting said cylindrical sections to form a symmetric structure, a heater symmetrically mounted on side of said web, a sample cell disposed in one tubular section, a reference cell disposed in the other tubular section, means interconnecting an input of said sample cell through a source to the output of a gas chromatograph means connecting the input to said reference cell to a source of carrier gas identical to that used in said gas chromatograph, a housing connected to said base plate and enclosing said furnace element, sample and reference cells, means interconnecting the ends of said sample and reference cells to said housing to suspend the same within each respective cylindrical section without making physical contact therewith, and a thermal insulated packing disposed to fill the space surrounding said furnace element and within said housing.
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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) | 1976-01-16 | 1976-07-17 | 1977-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-16 | 1980-07-17 | 1981-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-16 | 1984-07-17 | 1985-01-16 | $7700.00 | Window Closed / Lapsed |