DE10200797A1 - Infrared absorption gas sensor for determining concentration of infrared active gases in mixtures, comprises radiation source, detector and mirror - Google Patents
Infrared absorption gas sensor for determining concentration of infrared active gases in mixtures, comprises radiation source, detector and mirrorInfo
- Publication number
- DE10200797A1 DE10200797A1 DE10200797A DE10200797A DE10200797A1 DE 10200797 A1 DE10200797 A1 DE 10200797A1 DE 10200797 A DE10200797 A DE 10200797A DE 10200797 A DE10200797 A DE 10200797A DE 10200797 A1 DE10200797 A1 DE 10200797A1
- Authority
- DE
- Germany
- Prior art keywords
- gas sensor
- sensor according
- infrared
- radiation source
- mirror
- 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- Withdrawn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
- 239000007789 gas Substances 0.000 title claims abstract description 25
- 230000005855 radiation Effects 0.000 title claims abstract description 15
- 238000010521 absorption reaction Methods 0.000 title claims abstract description 7
- 239000000203 mixture Substances 0.000 title claims abstract 3
- 230000003287 optical effect Effects 0.000 claims abstract description 3
- 238000003384 imaging method Methods 0.000 claims description 7
- 238000001514 detection method Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims 1
- 125000006850 spacer group Chemical group 0.000 claims 1
- 239000011248 coating agent Substances 0.000 abstract 1
- 238000000576 coating method Methods 0.000 abstract 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 230000003595 spectral effect Effects 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000007740 vapor deposition Methods 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
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
Description
Die Erfindung betrifft einen Gassensor der nach dem bekannten Prinzip der
selektiven Absorption im infraroten Spektralbereich von 2-12 µm arbeitet. Die von
einer Strahlungsquelle (1) ausgehende breitbandige Infrarotstrahlung wird auf dem
Weg zum Empfangsdetektor (2) durch die anwesenden Gase (z. B. Kohlendioxid
CO2 oder Methan CH4) in bestimmten Spektralbereichen absorbiert. Die
Absorptionsbande für Kohlendioxid liegt beispielsweise bei 4,3 µm während die
Absorption durch Methan bei 3,4 µm am grössten ist. Die spektrale Selektion wird
dann durch vorgeschaltete Interferenzfilter durchgeführt, die bei bestimmten
Ausführungen von Empfangsdetektoren integraler Bestandteil sind. Bei breitbandigen
Detektoren muss dass Interferenzfilter zusätzlich in der Strahlengang integriert
werden. Die Auswertung der Strahlungsintensitäten erfolgt dabei nach dem
sogenannten Lambert-Beerschen-Gesetz.
I(c) = I0e- α cL
I(c) = Intensität bei einer Gaskonzentration c
I0 = Intensität bei c = 0
c = Gaskonzentration
α = Absorptionskoeffizient
L = Anstand (optischer Weg) zwischen der Strahlungsquelle und dem
Empfangsdetektor
The invention relates to a gas sensor which works according to the known principle of selective absorption in the infrared spectral range of 2-12 microns. The broadband infrared radiation emanating from a radiation source ( 1 ) is absorbed in certain spectral ranges on the way to the reception detector ( 2 ) by the gases present (for example carbon dioxide CO 2 or methane CH 4 ). The absorption band for carbon dioxide is, for example, 4.3 µm, while the absorption by methane is greatest at 3.4 µm. The spectral selection is then carried out by upstream interference filters, which are an integral part of certain designs of reception detectors. In the case of broadband detectors, the interference filter must also be integrated in the beam path. The radiation intensities are evaluated according to the so-called Lambert-Beerschen law.
I (c) = I 0 e - α cL
I (c) = intensity at a gas concentration c
I 0 = intensity at c = 0
c = gas concentration
α = absorption coefficient
L = distance (optical path) between the radiation source and the reception detector
Für eine gute Nachweisempfindlichkeit (Signal/Rausch-Verhältniss) sollte die Strahlungsintensität I0 und die Distanz L möglichst gross gewählt werden. Aufgrund der hohen Strahlungsdivergenz inkoheränter Strahlungsquellen (Glühstrahler) nimmt die Intensität mit steigender Distanz L aber drastisch ab. Um diese Verluste zu kompensieren muss man die Strahlerleistung erhöhen, so dass der elektrische Energieverbrauch zum Betrieb des Sensors ebenfalls drastisch ansteigt. Für viele Anwendungsfälle, bei denen eine reduzierte Leitungsaufnahme erforderlich ist, kann dieser Weg daher nicht beschritten werden. For good detection sensitivity (signal / noise ratio), the radiation intensity I 0 and the distance L should be chosen as large as possible. Due to the high radiation divergence of incoherent radiation sources (glow emitters), the intensity decreases drastically with increasing distance L. In order to compensate for these losses, the radiator power must be increased so that the electrical energy consumption for operating the sensor also increases drastically. For many applications where a reduced cable consumption is required, this path cannot be taken.
Die Aufgabe der vorliegenden Erfindung ist es daher einen Gassensor zu entwickeln,
der eine möglichst geringe elektrische Leistungsaufnahme hat und gleichzeitig eine
ausreichende Distanz L zwischen der Strahlungsquelle (1) und dem
Empfangsdetektor (2) aufweist, um einen möglichst grossen Messefekt [I0-I(c)] zu
generieren. Die mittlere Distanz L ergibt sich dabei aus den vorgegebenen
geometrischen Grössen:
The object of the present invention is therefore to develop a gas sensor which has the lowest possible electrical power consumption and at the same time has a sufficient distance L between the radiation source ( 1 ) and the reception detector ( 2 ) in order to maximize the measurement defect [I 0 -I (c)] to generate. The average distance L results from the given geometric sizes:
Die Lösung der erfindungsgemässen Aufgabe ergibt sich aus den kennzeichnenden Merkmalen des Anspruches 1 in zusammenwirken mit den Merkmalen des Oberbegriffes. Weitere vorteilhafte Ausführungen der Erfindung ergeben sich aus den Unteransprüchen. The achievement of the object according to the invention results from the characterizing ones Features of claim 1 in cooperation with the features of Preamble. Further advantageous embodiments of the invention result from the subclaims.
Ein wesentlicher Vorteil des Gassensors nach Anspruch 1 besteht darin, dass nahezu 50% der Infrarotstrahlung (8) auf den Empfangsdetektor (2) fokussiert werden, und somit eine sehr grosses Intensität 10 generiert werden kann. In der nachfolgenden Verstärkereinheit kann somit der Verstärkungsgrad reduziert werden, um das Signal/Rauschverhältnis zu verbessern. Weiterhin kann auch ein Teil der Streustrahlung (9) auf den Empfangsdetektor (2) gelangen, wenn die Hülse (5) innenseitig mit einer reflektierenden Schicht (10) versehen ist. A major advantage of the gas sensor according to claim 1 is that almost 50% of the infrared radiation ( 8 ) is focused on the reception detector ( 2 ), and thus a very high intensity 10 can be generated. The degree of amplification can thus be reduced in the subsequent amplifier unit in order to improve the signal / noise ratio. Furthermore, part of the scattered radiation ( 9 ) can reach the reception detector ( 2 ) if the sleeve ( 5 ) is provided on the inside with a reflective layer ( 10 ).
Je nach Anwendungsfall sind die zu analysierenden Gaskonzentrationen sehr unterschiedlich. Um eine leichte Adaption an die jeweiligen Messaufgaben zu ermöglichen kann zwischen der Halterung (6) für die Strahlungsquelle (1) und dem Empfangsdetektor (2) eine Hülse (5) integriert werden, die zu einer Verlängerung der Distanz L führt. Dies ist insbesondere für den Nachweis kleiner Gaskonzentrationen c erforderlich. Der Krümmungsradius R muss dann allerdings entsprechend angepasst werden. Depending on the application, the gas concentrations to be analyzed are very different. In order to enable easy adaptation to the respective measuring tasks, a sleeve ( 5 ) can be integrated between the holder ( 6 ) for the radiation source ( 1 ) and the reception detector ( 2 ), which leads to an extension of the distance L. This is particularly necessary for the detection of small gas concentrations c. The radius of curvature R must then be adjusted accordingly.
Der gesamte Sensoraufbau bestehend aus Halterung (6), Hülse (5) und abbildenden Spiegel (7) kann aus Kunststoff hergestellt werden, und ist somit für eine kostengünstige Massenfertigung (z. B. Spritzgussverfahren) geeignet. Die Beschichtung der Innenseiten kann dabei mit unterschiedlichen Materialien (Gold oder Aluminium) und mit unterschiedlichen Verfahren (Aufdampfen, Sputtern oder galvanisch) erfolgen. The entire sensor structure consisting of holder ( 6 ), sleeve ( 5 ) and imaging mirror ( 7 ) can be made of plastic and is therefore suitable for inexpensive mass production (e.g. injection molding). The inside can be coated with different materials (gold or aluminum) and with different methods (vapor deposition, sputtering or galvanic).
Ein zusätzlicher Vorteil ergibt sich dabei aus der geringen thermischen Leitfähigkeit von Kunststoff, der eine Energieübertragung von der beheizten Strahlungsquelle (1) zu dem temperaturempfindlichen Empfangsdetektor (2) entlang der Strecke 2s unterdrückt. Der Temperaturfehler des Gassensors ist somit auch reduziert. Durch die Umlenkung mit Hilfe des abbildenden Spiegels (7) sind die Ausmasse des gesamten Gassensors ca. um den Faktor 2 kleiner, so dass ein sehr kompakter Aufbau realisiert werden kann. Da sich alle elektrischen Anschlüsse auf der Seite der Halterung (6) befinden, kann der Gassensor auch direkt auf einer Leiterkarte angeordnet werden, was einen zusätzlichen fertigungstechnischen Vorteil darstellt. An additional advantage results from the low thermal conductivity of plastic, which suppresses energy transmission from the heated radiation source ( 1 ) to the temperature-sensitive reception detector ( 2 ) along the route for 2 s. The temperature error of the gas sensor is also reduced. Due to the deflection with the aid of the imaging mirror ( 7 ), the dimensions of the entire gas sensor are approximately two times smaller, so that a very compact construction can be achieved. Since all electrical connections are on the side of the holder ( 6 ), the gas sensor can also be arranged directly on a printed circuit board, which represents an additional manufacturing advantage.
Claims (9)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10200797A DE10200797A1 (en) | 2002-01-11 | 2002-01-11 | Infrared absorption gas sensor for determining concentration of infrared active gases in mixtures, comprises radiation source, detector and mirror |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10200797A DE10200797A1 (en) | 2002-01-11 | 2002-01-11 | Infrared absorption gas sensor for determining concentration of infrared active gases in mixtures, comprises radiation source, detector and mirror |
Publications (1)
Publication Number | Publication Date |
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DE10200797A1 true DE10200797A1 (en) | 2003-07-24 |
Family
ID=7711890
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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DE10200797A Withdrawn DE10200797A1 (en) | 2002-01-11 | 2002-01-11 | Infrared absorption gas sensor for determining concentration of infrared active gases in mixtures, comprises radiation source, detector and mirror |
Country Status (1)
Country | Link |
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DE (1) | DE10200797A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102004028023A1 (en) * | 2004-06-09 | 2005-12-29 | Perkinelmer Optoelectronics Gmbh & Co.Kg | Sensor unit for detecting a fluid, in particular for detecting natural gas, hydrocarbons, carbon dioxide or the like. In ambient air |
WO2007091043A1 (en) * | 2006-02-06 | 2007-08-16 | Gas Sensing Solutions Limited | Dome gas sensor |
-
2002
- 2002-01-11 DE DE10200797A patent/DE10200797A1/en not_active Withdrawn
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102004028023A1 (en) * | 2004-06-09 | 2005-12-29 | Perkinelmer Optoelectronics Gmbh & Co.Kg | Sensor unit for detecting a fluid, in particular for detecting natural gas, hydrocarbons, carbon dioxide or the like. In ambient air |
DE102004028023B4 (en) * | 2004-06-09 | 2006-07-06 | Perkinelmer Optoelectronics Gmbh & Co.Kg | Sensor unit for detecting a fluid, in particular for detecting natural gas, hydrocarbons, carbon dioxide or the like. In ambient air |
WO2007091043A1 (en) * | 2006-02-06 | 2007-08-16 | Gas Sensing Solutions Limited | Dome gas sensor |
AU2007213575B2 (en) * | 2006-02-06 | 2012-06-07 | Gas Sensing Solutions Limited | Dome gas sensor |
KR101339076B1 (en) * | 2006-02-06 | 2014-01-10 | 가스 센싱 솔루션즈 리미티드 | Dome gas sensor |
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Legal Events
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8110 | Request for examination paragraph 44 | ||
8130 | Withdrawal |