WO1996031765A1 - Appareil de mesure photo-acoustique - Google Patents

Appareil de mesure photo-acoustique Download PDF

Info

Publication number
WO1996031765A1
WO1996031765A1 PCT/NO1996/000074 NO9600074W WO9631765A1 WO 1996031765 A1 WO1996031765 A1 WO 1996031765A1 NO 9600074 W NO9600074 W NO 9600074W WO 9631765 A1 WO9631765 A1 WO 9631765A1
Authority
WO
WIPO (PCT)
Prior art keywords
detector
gas
photoacoustic
radiation
radiation source
Prior art date
Application number
PCT/NO1996/000074
Other languages
English (en)
Inventor
Alain Ferber
Ralph W. Bernstein
Original Assignee
Nyfotek A/S
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nyfotek A/S filed Critical Nyfotek A/S
Priority to AU53487/96A priority Critical patent/AU5348796A/en
Priority to EP96910237A priority patent/EP0819243A1/fr
Publication of WO1996031765A1 publication Critical patent/WO1996031765A1/fr

Links

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
    • G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids

Definitions

  • This invention relates to a photoacoustic measuring apparatus intended for gases and gas mixtures, comprising a pulsed or modulated radiation source adapted to illuminate a gas volume to be detected or be subjected to measurement, and a photoacoustic detector.
  • Photoacoustic techniques are based on a heating effect being known as the photothermal effect. These techniques utilize the principle that absorbed radiation energy, in particular infrared (IR) radiation, results in pressure variations in a confined gas volume, whereby the pressure variations are proportional to the absorbed amount of energy. These pressure variations can then be detected by means of a sensitive pressure transducer.
  • IR infrared
  • a photoacoustic gas detector of the kind described in the applicant's application No. 95.0505.
  • This particular gas detector comprises a chamber for receiving the gas or gas mixture concerned, a path for pulsed or modulated IR radiation into, through and out of the chamber, and a pressure sensor being adapted to measure pressure changes in the chamber resulting from applied IR radiation.
  • gas detectors made of silicium are transparent to IR radiation, but not to visible light.
  • the photoacoustic techniques can be used in the case of gas molecules having two or more atoms and having absorption lines for vibration/rotation for example in the infrared range between 2 and 25 ⁇ .
  • the detector is filled with a controlled amount of the gas or gas mixture concerned. Moreover according to the invention it is possible to let the gas volume to be detected or measured, be located between the source of radiation and the detector.
  • a further more parti ⁇ cular feature being comprised by the invention consists in the provision of a reference detector in association with the above and essential photoacoustic detector in the measurement apparatus.
  • FIG. 1 schematically and simpified shows a first embodiment of the measuring apparatus according to the in ⁇ vention
  • fig. 2 shows another and modified embodiment of the measuring apparatus.
  • a number of elements are incorporated in both embodiments being shown in the drawings, and these are the following elements:
  • a radiation source 4 for example an IR source being provided with a reflector 4A for directing a radiation beam 2 through a measurement volume 10 of the gas or gas mixture concerned, towards the actual photoacoustic detector.
  • This comprises a closed cavity l having an optical window 6 for the radiation or illumination 2 from the source 4, so that an amount of gas or gas mixture being received in the cavity or receptacle l, can be illuminated.
  • the cavity can be provided in a housing of silicium or other transparent material, where the cavity can be formed by means of common semiconductor planar techniques, so called micromachining.
  • the cavity l must be able to be sealed in a completely tight manner after the introduction og the gas or gas mixture concerned into it. If the housing or a wall thereof is made of silicium, for example the window 6, this will constitute an optical window in the IR range.
  • a mirror device (reflector) 11 advantageously can be arranged at the end of the cavity 1 so as to send "unused" radiation out of the detector. With such a reflector, thermal absorbtion in the walls will be avoided.
  • two microphones 3A and 3B which can be in the form of sensitive pressure transducers or sensors, so as to detect or measure pressure signals caused by the photo ⁇ acoustic effect during measurement.
  • a controlled or well defined and constant amount of gas or gas mixture of the same type as the one to be detected or measured, is introduced into the cavity l before it is sealed.
  • a necessary pre- requisite is that the gas shall have a constant pressure, i.e. partial pressure, which is not necessarily equal to the pressure in the gas or measurement volume 10.
  • the output signals from both microphones 3A and 3B are passed through a circuit 8A for summing or other combination of the two signals, to an electronic measurement circuit which can comprise more or less comprehensive signal process ⁇ ing and besides a display or print-out of the measurement results.
  • the modified embodiment in fig. 2 comprises in particular a reference detector 9 receiving illumination from the source 4 after propagation of the radiation through the cavity l of the detector, this being here provided with another optical window 16 in a wall opposite to the first window 6, so that the radiation path from the source 4 goes directly through the main detector and reaches the reference detector 9.
  • This detector accordingly will measure a reference signal which makes it possible to correct for drift in the radiation source 4 or undesired masking effects being caused for exam ⁇ ple by dust or smoke in the measurement volume 10.
  • a referece detector can be located and oriented in other ways in relation to the main detector 1 and the source 4, than what is illustrated in fig. 2. Even though it is an advantage that the reference detector receives its proportion of the illumination after propagation through the main detector, a reference detector may also be useful for the above mentioned correction, when located in a different manner, for example so that it receives its illumination more or less directely from the source 4.
  • a photoacoustic detector in a measuring apparatus as described above has a manner of operation being in short as follows:
  • the detector generates a signal being proportional to the photoacoustic effect in the cavity 1 of the detector, whereby the signal will be a maximum when there is no gas or gas mixture present in the measurement volume, i.e. between the source 4 and the detector 1.
  • a determination of or a measure of the gas concentration in the measurement volume 10 is derived by taking as a starting point the difference between the maximum signal mentioned and the measurement signal. The concentration will be substantially proportional to this difference, provided that only neglictable saturation effects are present in connection with the measurement.
  • the actual structure of the detector as such, with its reseptacle or cavity 1, being filled with the known amount of gas or gas mixture as mentioned, can be varied in many ways. This for example applies to the number of microphones, which can be one, two or more. As mentioned in the introduction of this description, it may also be an advantage in many applications to employ a gas detector of the kind described in patent application No. 95.0505 mentioned above.

Landscapes

  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

Cette invention concerne un appareil de mesure photo-acoustique pour gaz et mélanges gazeux, lequel comprend, d'une part, une source de rayonnement pulsé ou modulé (4) destinée à éclairer un volume de gaz (10) devant être détecté ou mesuré, et, d'autre part, un détecteur photo-acoustique (1). Ce détecteur photo-acoustique (1) est rempli d'un certain volume d'un gaz ou d'un mélange gazeux du même type que celui (10) qui doit être détecté ou mesuré.
PCT/NO1996/000074 1995-04-05 1996-04-01 Appareil de mesure photo-acoustique WO1996031765A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU53487/96A AU5348796A (en) 1995-04-05 1996-04-01 Photoacoustic measuring apparatus
EP96910237A EP0819243A1 (fr) 1995-04-05 1996-04-01 Appareil de mesure photo-acoustique

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO951334A NO300346B1 (no) 1995-04-05 1995-04-05 Foto-akustisk måleanordning
NO951334 1995-04-05

Publications (1)

Publication Number Publication Date
WO1996031765A1 true WO1996031765A1 (fr) 1996-10-10

Family

ID=19898089

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO1996/000074 WO1996031765A1 (fr) 1995-04-05 1996-04-01 Appareil de mesure photo-acoustique

Country Status (4)

Country Link
EP (1) EP0819243A1 (fr)
AU (1) AU5348796A (fr)
NO (1) NO300346B1 (fr)
WO (1) WO1996031765A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999044040A1 (fr) * 1998-02-26 1999-09-02 Presens As Procede de mesure de la concentration d'un gaz a fonction de correction de derive et detecteur de gaz photo-acoustique
WO2004008112A1 (fr) * 2002-07-12 2004-01-22 Abb Research Ltd Spectrometre d'absorption a haute resolution et procede de mesure correspondant
CN103954561A (zh) * 2014-05-14 2014-07-30 江苏舒茨测控设备有限公司 用于检测二氧化硫浓度的光声光谱检测装置
US8848191B2 (en) 2012-03-14 2014-09-30 Honeywell International Inc. Photoacoustic sensor with mirror
RU2681260C2 (ru) * 2014-06-16 2019-03-05 Диамонтех Гмбх Неинвазивный анализ материала
US10876965B2 (en) 2015-12-09 2020-12-29 Diamontech Ag Apparatus and method for analyzing a material
US11280728B2 (en) 2015-12-09 2022-03-22 Diamontech Ag Device and method for analyzing a material

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5159411A (en) * 1988-09-12 1992-10-27 Fls Airloq A/S Method and apparatus for the detection of a gas using photoacoustic spectroscopy
EP0685728A1 (fr) * 1994-06-04 1995-12-06 Orbisphere Laboratories Neuchatel Sa Appareil et méthode d'analyse photoacoustique

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5159411A (en) * 1988-09-12 1992-10-27 Fls Airloq A/S Method and apparatus for the detection of a gas using photoacoustic spectroscopy
EP0685728A1 (fr) * 1994-06-04 1995-12-06 Orbisphere Laboratories Neuchatel Sa Appareil et méthode d'analyse photoacoustique

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999044040A1 (fr) * 1998-02-26 1999-09-02 Presens As Procede de mesure de la concentration d'un gaz a fonction de correction de derive et detecteur de gaz photo-acoustique
WO2004008112A1 (fr) * 2002-07-12 2004-01-22 Abb Research Ltd Spectrometre d'absorption a haute resolution et procede de mesure correspondant
US8848191B2 (en) 2012-03-14 2014-09-30 Honeywell International Inc. Photoacoustic sensor with mirror
CN103954561A (zh) * 2014-05-14 2014-07-30 江苏舒茨测控设备有限公司 用于检测二氧化硫浓度的光声光谱检测装置
RU2681260C2 (ru) * 2014-06-16 2019-03-05 Диамонтех Гмбх Неинвазивный анализ материала
US10883933B2 (en) 2014-06-16 2021-01-05 Diamontech Ag Non-invasive substance analysis
US11639894B2 (en) 2014-06-16 2023-05-02 Diamontech Ag Non-invasive substance analysis
US10876965B2 (en) 2015-12-09 2020-12-29 Diamontech Ag Apparatus and method for analyzing a material
US11280728B2 (en) 2015-12-09 2022-03-22 Diamontech Ag Device and method for analyzing a material

Also Published As

Publication number Publication date
NO300346B1 (no) 1997-05-12
NO951334D0 (no) 1995-04-05
AU5348796A (en) 1996-10-23
NO951334L (no) 1996-10-07
EP0819243A1 (fr) 1998-01-21

Similar Documents

Publication Publication Date Title
US5753797A (en) Photo-acoustic gas sensor and its manufacture and use
US6469303B1 (en) Non-dispersive infrared gas sensor
US6509567B2 (en) Method and apparatus for detecting gases
US3916195A (en) Non-dispersive multiple gas analyzer
US4215940A (en) Optode arrangement
PL1549932T3 (pl) Sposób wykrywania gazu i urządzenie do wykrywania gazu
US6989549B2 (en) Optical gas sensor
US20120318041A1 (en) Method and apparatus for measuring gas concentrations
US6642522B2 (en) Optical gas sensor
JPH08304282A (ja) ガス分析装置
CA1186402A (fr) Detecteur photo-acoustique a debit
JPH10148629A (ja) 分光方法及び装置
EP0819243A1 (fr) Appareil de mesure photo-acoustique
CN114062273B (zh) 一种抗干扰光纤光声气体传感系统及方法
JPH08178870A (ja) 材料サンプルの微小吸収量あるいは反射量を測定する分光学的方法および装置
US4682897A (en) Light scattering measuring apparatus
GB2181536A (en) Wavelength scanning optical sensor
US3920993A (en) Piggyback optical bench
JPH08271336A (ja) 光音響分光測定装置
CN217846054U (zh) 气体检测装置
Betteridge et al. Analytical aspects of photoacoustic spectroscopy
CN209821055U (zh) 抗干扰的光声光谱气体检测装置
JPS57111435A (en) Measuring device for absorption intensity of infrared ray by atr method
JPS5994027A (ja) 光音響効果型測定装置
JPH09251004A (ja) 光音響分析方法およびその装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AL AM AT AU AZ BB BG BR BY CA CH CN CZ DE DK EE ES FI GB GE HU IS JP KE KG KP KR KZ LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK TJ TM TR TT UA UG US UZ VN AM AZ BY KG KZ MD RU TJ TM

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): KE LS MW SD SZ UG AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 1996910237

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 1996910237

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

NENP Non-entry into the national phase

Ref country code: CA

WWW Wipo information: withdrawn in national office

Ref document number: 1996910237

Country of ref document: EP