GB2134253A - Source for infrared gas analysis - Google Patents
Source for infrared gas analysis Download PDFInfo
- Publication number
- GB2134253A GB2134253A GB08333439A GB8333439A GB2134253A GB 2134253 A GB2134253 A GB 2134253A GB 08333439 A GB08333439 A GB 08333439A GB 8333439 A GB8333439 A GB 8333439A GB 2134253 A GB2134253 A GB 2134253A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cylinder
- gas
- radiation
- chamber
- piston
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000004868 gas analysis Methods 0.000 title description 3
- 230000005855 radiation Effects 0.000 claims abstract description 45
- 239000000203 mixture Substances 0.000 claims abstract description 14
- 230000005291 magnetic effect Effects 0.000 claims abstract description 11
- 238000001845 vibrational spectrum Methods 0.000 claims abstract description 4
- 239000007789 gas Substances 0.000 claims description 30
- 230000003287 optical effect Effects 0.000 claims description 10
- 230000003595 spectral effect Effects 0.000 claims description 6
- 239000000654 additive Substances 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 5
- 230000006835 compression Effects 0.000 claims description 4
- 238000007906 compression Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000003302 ferromagnetic material Substances 0.000 claims description 2
- 238000000295 emission spectrum Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000005693 optoelectronics Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 229910052743 krypton Inorganic materials 0.000 description 1
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
- G01N2021/3531—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis without instrumental source, i.e. radiometric
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
A source of radiation pulses composed of: a cylinder 10 defining a sealed cylinder chamber and provided at one end with a radiation permeable window 15; a mass of gas 14 disposed in the cylinder chamber, the composition of the gas being such as to be adiabatically heated and excited to emit radiation in a rotation-vibration spectrum upon being compressed; and a piston 11 disposed in the chamber to be freely movable in the direction of the longitudinal axis 12 of the cylinder 10 for periodically compressing the gas. Preferably, the piston 11 is driven by magnetic forces acting in the direction of the longitudinal axis 12 of the cylinder. <IMAGE>
Description
SPECIFICATION
Selective measurement of the infrared radiation absorbing component of a mixture
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for selectively measuring the infrared radiation absorbing component of a mixture with the aid of radiation pulses which penetrate the mixture.
Such devices are needed for highly sensitive gas analysis instruments operating in the range of high resolution spectroscopy. Such instruments continuously monitor, for example, the composition of exhaust gas streams or the occurrence of certain gas components in such streams and have gained significance particularly in the processing art and for the implementation of environmental protection measures.
The previously available light sources in the infrared spectral range have a number of drawbacks, a particular one of which is that spectral emission takes place over a broad band. This drawback has the result, on the one hand, that many optical systems have too low a signal to noise ratio and, on the other hand, that the emission spectrum contains undesirable light wavelengths which reduce selectivity.
In an optoelectronic gas analysis device described in BMFT [Bundesministerium fur
Forschung und Technologie = Federal Ministry for Research and Technology] Research
Report T 81-209, the concentration of an infrared active gas is determined with the aid of a pulsed diode laser.
However, these laser systems, which can be used in many cases, also have drawbacks which are, in particular, that the system tends to be unstable with respect to frequency and amplitude, that gaps occur in the emission spectrum and that substantial investment costs are involved. Moreover, the longer wave infrared range requires complicated cooling assemblies for the operation of the diode lasers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a device which generates periodic radiation pulses of high radiation intensity and, preferably, emits a vibration-rotation line spectrum which is typical for certain gases.
The above and other objects are achieved, according to the invention, by the provision of a novel source of radiation pulses comprising:
a cylinder defining a sealed cylinder chamber and provided at one end with a radiation permeable window;
a mass of gas disposed in the cylinder chamber, the composition of the gas being such as to be adiabatically heated and excited to emit radiation in a rotation-vibration spectrum upon being compressed; and
a piston disposed in the chamber to be freely movable in the direction of the longitudinal axis of the cylinder for periodically compressing the gas.
The advantages realized by the invention are, in particular, that it is possible, by simple means and with low energy consumption, to create radiation pulses of high radiation power and spectral sensitivity without chopper arrangements, susceptible to interference, which would temporarily interrupt the beam and whose pulse repetition rate and amplitude can be set with great accuracy to predetermined values which are then kept constant with little effort.
One embodiment of an apparatus according to the invention is illustrated in the drawing and will be described in greater detail below.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a partly cross-sectional, partly schematic view of a device for measuring at least one component of a gas mixture with the aid of radiation produced by a selective radiation source.
Figure 2 is a simplified cross-sectional view of an embodiment of a selective radiation source without cooling device according to the invention for use in the device of Fig. 1.
DESCRIPTION OF THE PREFERRED EMBODI
MENTS
The basic configuration of an infrared analyzer which can employ a radiation source according to the invention is shown in Fig. 1.
The radiation periodically emitted in the form of radiation pulses by a selective radiation source 1 is conducted through a first lens system 2, an optical broadband filter 3 which filters out the major portion of the radiation frequencies not required for the absorption measurements, a measuring cuvette 4 through which flows the gas to be measured and whose gas pressure is measured by means of a pressure gauge 5, and a second lens system 6 to a thermal or optoelectronic detector 7, which is connected to an electronic measured value processing device 8 which forms a representation of the ratio of the measured radiation to reference radiation.
A control device 9 supplies the selective radiation source 1 with an alternating voltage whose amplitude and/or frequency can be set to predetermined values. A reference cuvette 4a filled with a non-absorbing gas is arranged in parallel with measuring cuvette 4. The radiation passing through the reference cuvette is conducted to a reference detector 7a indentical to detector 7.
Alternatively, a reference signal can be formed, in a known manner, with a reference cuvette 4a according to the single beam bifrequency principle, if the cylinder 10 is filled with a gas mixture, with part of the emitted spectrum not being absorbed by the mixture to be analyzed.
For analyzing e.g. a mixture containing HF it is possible to use HCI as a second gas in the radiation source. The emission spectrum of HCI shows no interference with that of HF.
If a radiation source in which the radiation is constant in time is employed, instead of the selective radiation source 1, it is necessary to place in the beam path between the first lens system 2 and the broadband filter 3 a chopper in the form of a filter wheel which is driven by a stepping motor and which is equipped with gas filters and/or solid state interference filters. If the selective radiation source 1 is employed, this filtering device, which is very susceptible to interference, can be omitted completely.
Such a radiation source 1 is shown in simplified form in Fig. 2 and includes a piston 11 made of a ferromagnetic material and arranged to be freely movable in the direction of the axis 1 2 of a cylinder 10 which is closed on all sides and is made of a nonmagnetic material. Each one of the two ends of cylinder 10 is surrounded by a respective magnetic coil 1 3 whose magnetic field acts on piston 11 and causes it to move in the direction of axis 1 2 of cylinder 10.
Magnetic coils 1 3 are connected to the output of control device 9 which supplies the magnetic coils 1 3 with an alternating voltage of adjustable amplitude and frequency.
The alternating voltage supplied to one coil 1 3 is phase shifted by 180 relative to that of the other coil 1 3. The frequency of this alternating voltage is here preferably set to the resonant frequency of the vibratory system comprising the piston 11 and the gas fill of cylinder 10.
Cylinder 10 is filled at both sides of piston 11 with a gas 14 which is periodically compressed and expanded by the piston 11 which oscillatingly moves under the influence of the alternating magnetic field of magnetic coils 1 3 and which, during the compression phase, is adiabatically heated and excited to emit radiation in a rotation-vibration spectrum.
At least one of the frontal faces of cylinder 10 is constituted by an optical window 1 5 for the exit of the radiation and is therefore made of a radiation transmitting material. It is also possible to provide an optical window 15 at each of the two frontal faces of cylinder 10 and to associate, for example, a respective measuring device of the type shown in Fig. 1 with each one of the two optical windows 1 5.
Piston 11 is guided with low friction in that a helical spring 1 6 which secures piston 11 against canting, or tilting, is provided between each of the two exposed frontal faces of piston 11 and the associated end of cylinder 10, and in that cylinder 10 is made of a material which has a low coefficient of friction, such as, for example Teflon or graphite.
In certain cases, it may also be of advantage to design the or each optical window 1 5 of cylinder 10 as an optical filter which filters out predetermined spectral ranges.
The optical filter is of the multilayer interference type. The spectral range of transmission of such filters which are commercially available is determined by the thickness of the layers which are deposited on a stable substrate by thin film techniques.
The efficiency of radiation source 1 can be increased in a simple manner in that a nonemitting additive gas 1 7 is mixed with the emitting gas 14, with the adiabatic coefficient of the additive gas causing the greatest possible increase in temperature at a predetermined compression ratio.
Such additive gases may be, for example, argon, krypton or helium.
In certain cases it may also be of advantage for the gas 14 emitting the radiation to comprise at least two components and to be composed, for example, of a mixture of HF and H20 or NO and NO2 or CO and CO2.
The intensity of the emitted radiation can be increased in a simple manner by forming the interior surface of cylinder 10 to reflect radiation. This is possible, for example, with a cylinder made of high-grade nonmagnetic steel, by polishing the interior surface to a high gloss.
A typical radiation source consists of a cylinder 10 with length of 10 cm and a diameter of 1 cm. The volume of the partial chambers to each side of piston 11 are 3 cm3.
The compression ratio can be adjusted between a value of 10 to 80. For measuring HF the cylinder is filled with a mixture of 10%
HF and 90% Ar at atmospheric pressure. The optical windows consist of single crystal AI2O3 (sapphire).
Claims (8)
1. A source of radiation pulses comprising:
a cylinder defining a sealed cylinder chamber and provided at one end with a radiation permeable window;
a mass of gas disposed in said cylinder chamber, the composition of said gas being such as to be adiabatically heated and excited to emit radiation in a rotation-vibration spectrum upon being compressed; and
a piston disposed in said chamber to be freely movable in the direction of the longitudinal axis of said cylinder for periodically compressing said gas.
2. An arrangement as defined in claim 1 further comprising means for supplying magnetic forces for moving said piston in the direction of the longitudinal axis of said cylinder.
3. An arrangement as defined in claim 2 wherein: said cylinder is made of a nonmagnetic material; said piston is made of a ferro magnetic material; and said means for supplying magnetic forces comprise two electromagnetic coils each surrounding a respective end of said cylinder for supplying the magnetic forces, and a control device connected to said coils for supplying thereto alternating voltages of adjustable amplitude and frequency for generating the magnetic forces.
4. An arrangement as defined in claim 1 further comprising two helical springs disposed in said cylinder chamber and each mounted between a respective axial end of said chamber and an associated end face of said piston for preventing tilting of said piston in said chamber.
5. An arrangement as defined in claim 1 wherein said window is an optical filter constructed to prevent passage of radiation in a selected spectral range.
6. An arrangement as defined in claim 1 further comprising an additive gas which does not emit radiation mixed with said mass of gas, said additive gas being selected to have an adiabatic coefficient which maximizes the temperature rise of said gases at a selected compression ratio.
7. An arrangement as defined in claim 1 wherein said mass of gas is a mixture of at least two components.
8. An arrangement as defined in claim 1 wherein said cylinder has an interior wall delimiting the lateral boundary of said chamber and constructed for reflecting the radiation emitted by said gas.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19823248070 DE3248070A1 (en) | 1982-12-24 | 1982-12-24 | DEVICE FOR SELECTIVELY MEASURING AN INFRARED RADIATION-ABSORBING COMPONENT OF A MIXTURE |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8333439D0 GB8333439D0 (en) | 1984-01-25 |
| GB2134253A true GB2134253A (en) | 1984-08-08 |
Family
ID=6181799
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08333439A Withdrawn GB2134253A (en) | 1982-12-24 | 1983-12-15 | Source for infrared gas analysis |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE3248070A1 (en) |
| FR (1) | FR2538548A1 (en) |
| GB (1) | GB2134253A (en) |
| NL (1) | NL8303954A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4782232A (en) * | 1986-09-22 | 1988-11-01 | Spectral Sciences, Inc. | Infrared molecular species monitor |
| US5172187A (en) * | 1990-04-06 | 1992-12-15 | Nokia Unterhaltungselektronik Gmbh | Method of determining the pretilt angle of liquid crystal molecules |
| EP1305810A1 (en) * | 2000-05-22 | 2003-05-02 | Shaul Yatsiv | Infrared spectral sources |
| US7330262B2 (en) | 2002-02-06 | 2008-02-12 | Endress+Hauser Conducta Gesellschaft Fur Mess - Und Regeltechnik Mbh+Co. Kg | Methods and apparatus for determining the content materials of a liquid employing a piston movable within a measuring chamber |
| CN104502541A (en) * | 2014-12-30 | 2015-04-08 | 力合科技（湖南）股份有限公司 | Gas chamber device for gas analyzer |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102009028254A1 (en) | 2009-04-22 | 2010-10-28 | Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. KG | Method for investigations on liquids and device therefor |
| CN113873851B (en) * | 2021-10-13 | 2024-04-09 | 燕山大学 | Radiation heat dissipation equipment |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4110618A (en) * | 1965-06-08 | 1978-08-29 | American Standard Inc. | Adiabatic compression infrared emission vapor detector |
| US3617737A (en) * | 1969-07-09 | 1971-11-02 | Nat Res Dev | Radiometer apparatus comprising a volume of gas whose pressure is cyclically varied |
| US3899252A (en) * | 1974-06-28 | 1975-08-12 | Nasa | Ndir gas analyzer based on absorption modulation ratios for known and unknown samples |
| US4274063A (en) * | 1976-12-30 | 1981-06-16 | Ali Javan | Infrared spectroscopic lamps and gas detectors incorporating such lamps |
-
1982
- 1982-12-24 DE DE19823248070 patent/DE3248070A1/en not_active Withdrawn
-
1983
- 1983-11-17 NL NL8303954A patent/NL8303954A/en not_active Application Discontinuation
- 1983-12-15 GB GB08333439A patent/GB2134253A/en not_active Withdrawn
- 1983-12-23 FR FR8320687A patent/FR2538548A1/en not_active Withdrawn
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4782232A (en) * | 1986-09-22 | 1988-11-01 | Spectral Sciences, Inc. | Infrared molecular species monitor |
| US5172187A (en) * | 1990-04-06 | 1992-12-15 | Nokia Unterhaltungselektronik Gmbh | Method of determining the pretilt angle of liquid crystal molecules |
| EP1305810A1 (en) * | 2000-05-22 | 2003-05-02 | Shaul Yatsiv | Infrared spectral sources |
| EP1305810A4 (en) * | 2000-05-22 | 2006-02-22 | Shaul Yatsiv | Infrared spectral sources |
| US7330262B2 (en) | 2002-02-06 | 2008-02-12 | Endress+Hauser Conducta Gesellschaft Fur Mess - Und Regeltechnik Mbh+Co. Kg | Methods and apparatus for determining the content materials of a liquid employing a piston movable within a measuring chamber |
| CN104502541A (en) * | 2014-12-30 | 2015-04-08 | 力合科技（湖南）股份有限公司 | Gas chamber device for gas analyzer |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3248070A1 (en) | 1984-06-28 |
| GB8333439D0 (en) | 1984-01-25 |
| FR2538548A1 (en) | 1984-06-29 |
| NL8303954A (en) | 1984-07-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |