CN201034929Y - Optical fiber gas sensors - Google Patents
Optical fiber gas sensors Download PDFInfo
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- CN201034929Y CN201034929Y CNU2007200365415U CN200720036541U CN201034929Y CN 201034929 Y CN201034929 Y CN 201034929Y CN U2007200365415 U CNU2007200365415 U CN U2007200365415U CN 200720036541 U CN200720036541 U CN 200720036541U CN 201034929 Y CN201034929 Y CN 201034929Y
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Abstract
An optical fiber gas sensor adopts a low reflection cavity mirror and an optical fiber fabry-perot interferometer for measuring fiber composition to detect the acousto pressure wave signal produced when gas absorb light energy, which provides a new implementation method for acousto-optic gas sensing technology; the excitation light which is modulated by the pulse sent out by excitation source passes the band-pass filter and enters the air cavity from the air cavity window; after the excitation light in the air cavity is absorbed by being measured gas, then the acousto pressure wave whose intensity corresponds to the concentration of the being measured gas is formed; the acousto pressure wave is converted into the vibration of vibration diaphragm by the vibration diaphragm disposed at the other port of the air cavity, the measuring optical signal which is sent out by the measuring source driven by the first driving power passes through the fiber wave combiner, the transmission fiber and the fiber wave separator, and enters the measuring fiber of the fabry-perot interferometer, the return beam and the beam directly reflected by the optical fiber end face have an optical path difference, which can conclude the concentration value of the being measured gas.
Description
Technical Field
The present invention relates to photoacoustic gas sensing methods and sensors, and more particularly to a device for detecting photoacoustic signals using low finesse fiber fabry-perot interference. The utility model belongs to the technical field of the optical fiber sensing, the sensing of mainly used gaseous state material's concentration detects.
Background
The detection of gas, especially combustible, explosive, toxic and harmful gas, is of great importance to industrial and agricultural production, people's life, scientific research and national safety.
The use of gas sensors to detect the concentration of gaseous analytes using the photoacoustic effect is well known, as the prior art [ U.S. patent No.4740086] describes the use of photoacoustic gas sensors to convert the light energy of an amplitude modulated light source into acoustic energy when optically exciting a gaseous analyte. When the light energy incident to the gas chamber is absorbed by the gas to be measured, a sound pressure wave having an intensity corresponding to the concentration of the gas to be measured in the gas chamber is generated, and the sound pressure wave is detected by the capacitive microphone. The photoacoustic gas sensing technology has a series of advantages of high sensitivity, small volume required by a gas chamber and the like, and is widely researched and applied.
The optical fiber sensor has the advantages of electromagnetic interference resistance, high sensitivity, good electrical insulation, safety, reliability, corrosion resistance, convenience for multiplexing and networking and the like, so the optical fiber sensor has wide application prospects in various fields of industry, agriculture, biomedical treatment, national defense and the like. In order to combine the photoacoustic gas sensing principle and the optical fiber sensing technology and integrate the advantages of the photoacoustic gas sensing principle and the optical fiber sensing technology to form a novel optical fiber photoacoustic gas sensing technology, a plurality of technical schemes have been proposed. In the second prior art [ study of fiber gas sensors based on photoacoustic spectroscopy, china laser, volume 31, phase 8, and year 2004 ], a scheme is proposed in which a conventional microphone is replaced by a fiber mach-zehnder interferometer phase sensor, one arm of the fiber mach-zehnder interferometer is wound around the outer wall of a photoacoustic air cavity, and when the gas absorbs light energy to generate a sound pressure wave, the sound pressure wave changes the diameter of the photoacoustic air cavity, so that the optical fiber wound around the photoacoustic air cavity generates radial strain to cause phase change of the light wave, and the sound pressure wave change is sensed by measuring the phase change, thereby obtaining gas concentration information. However, due to thermal expansion and cold contraction, the diameter of the photoacoustic cavity can be changed due to the change of the ambient temperature, the reference arm optical fiber can be influenced by the airflow and the temperature outside the photoacoustic cavity, and the winding of the optical fiber can generate double refraction, so that large phase noise irrelevant to gas absorption is generated, and the low measurement sensitivity and the poor measurement stability are caused. In addition, the excitation light source adopts a dye laser, so that the volume is large; the light intensity modulation adopts a mechanical chopper, and the frequency is low. So that the advantages of the optical fiber sensing technology are not fully exerted.
For another example, CN200510012344.5 optical fiber gas sensor includes a light source, a coupler, a gas absorption cell, a contrast optical fiber, a photodetector, and a signal collecting and processing system, where the light source, the coupler, the gas absorption cell, the contrast optical fiber, and the photodetector are connected by a common solid optical fiber, and the optical fiber and the contrast optical fiber in the gas absorption cell are microstructure hollow optical fibers, and the connection relationship is as follows: the light source is connected with the input of the coupler, one path of output of the coupler is connected with the gas absorption cell, the gas absorption cell is connected with the photoelectric detector, the other path of output of the coupler is connected with the contrast optical fiber, the contrast optical fiber is connected with the photoelectric detector, and the output of the photoelectric detector is connected with the signal acquisition and processing system.
CN200610012988.9 hollow core photon crystal optical fiber gas sensor is a hollow core photon crystal optical fiber gas sensor. The gas sensor comprises a light source, a light guide air chamber light path connected with the light source through a common optical fiber and an optical splitter, a reference light path adopting the common optical fiber, and a signal conversion part which is arranged at the other end of the light guide air chamber light path and the reference light path and comprises a photodiode and a phase-locked amplifier and is used for providing signals for an external gas concentration monitoring circuit, wherein the light guide air chamber adopts a hollow photonic crystal optical fiber on which micron-sized air-permeable micropores are formed.
Disclosure of Invention
The utility model discloses the purpose does: a sensor for detecting photoacoustic signals by using low-fineness optical fiber Fabry-Perot interference is provided, and an optical fiber photoacoustic gas sensor with high stability and high sensitivity is provided.
The optical fiber gas sensor comprises a measuring light source 1, an excitation light source 2, an optical fiber combiner 3, an optical fiber light guide element 4, a transmission optical fiber 5, an optical fiber wave separator 6, a band-pass filter 8, an air cavity window 9, an air cavity 11 filled with gas to be measured 14, a low-fineness Fabry-Perot interference module 15 consisting of a low-reflection cavity mirror (a vibrating diaphragm 151) and a measuring optical fiber 152, a photoelectric detection unit 16, a phase demodulation module 19 and a signal processing and control system 20; adopting a low reflection cavity mirror and a measuring optical fiber to form an optical fiber Fabry-Perot interferometer; an excitation light source 2 is connected with an optical fiber wave combiner 3, a transmission optical fiber 5, an optical fiber wave separator 6 and a band-pass filter 8, and enters an air cavity 11 from an air cavity window 9; exciting light incident into the air cavity 11 is absorbed by the gas to be measured 14, and acoustic pressure waves are generated and converted into vibration of the vibrating diaphragm 151 by the vibrating diaphragm 151 at the other port of the air cavity 11, wherein the vibrating diaphragm is a low-reflection cavity mirror; the measurement light signal emitted by the measurement light source 1 is connected with the optical fiber combiner 3, the transmission optical fiber 5 and the optical fiber wave splitter 6, enters the measurement optical fiber 152 of the fabry-perot interferometer, and is transmitted to the end face of the optical fiber 152, there is an optical path difference between the light beam returned by the measurement light and the light beam directly reflected by the end face of the optical fiber 152, and the light signal reflected by the end face of the optical fiber 152 and the surface of the vibration diaphragm 151 passes through the optical fiber wave splitter 6, the transmission optical fiber 5, the phase demodulation module 17 and the signal processing and control system 20 to be analyzed, so as to obtain the concentration value of the gas to be measured. The optical fiber gas sensing adopts an optical fiber Fabry-Perot interferometer composed of a low-reflection cavity mirror and a measuring optical fiber to detect the sound pressure wave signal generated by the gas absorption light energy, and provides a new realization method for the photoacoustic gas sensing technology; especially, the excitation light source 2 emits pulse modulated excitation light, which enters the air cavity 11 from the air cavity window 9 through the band-pass filter 8; after the exciting light entering the air cavity 11 is absorbed by the gas to be measured 14, the sound pressure wave with the intensity corresponding to the concentration of the gas to be measured 14 in the air cavity 11 is generated; the sound pressure wave is converted into the vibration of the vibrating diaphragm 151 by the vibrating diaphragm 151 at the other port of the air cavity 11, the vibrating diaphragm is a low-reflection cavity mirror, a measuring light signal emitted by a measuring light source 1 driven by a first driving power supply 18 passes through an optical fiber combiner 3, a transmission optical fiber 5 and an optical fiber wave splitter 6, enters a measuring optical fiber 152 of a fabry-perot interferometer, is transmitted to the end face of the optical fiber 152, the transmitting light exits to the surface of the vibrating diaphragm 151, part of the light is returned to the optical fiber 152 after being reflected, an optical path difference exists between the returned light beam and a light beam directly reflected by the end face of the optical fiber, and the light signal reflected by the end face of the optical fiber 152 and the surface of the vibrating diaphragm 151 passes through the optical fiber wave splitter 6, the transmission optical fiber 5 and then passes through a phase demodulation module 17 and a signal processing and control system 20 to be analyzed to obtain the concentration value of the gas to be measured. The exciting light sequentially passes through the optical fiber wave combiner 3, the optical fiber light guide element 4, the transmission optical fiber 5 and the optical fiber wave separator 6, is emitted from the optical fiber collimator 7, and then passes through the band-pass filter 8 and enters the air cavity 11 from the air cavity window 9.
The utility model discloses an optic fibre optoacoustic gas sensor's basic working process as follows: as shown in fig. 1, an excitation light source 2 driven by a second driving power supply 19 emits pulsed excitation light, which sequentially passes through an optical fiber combiner 3, an optical fiber light guide element 4, a transmission optical fiber 5, and an optical fiber demultiplexer 6, exits from an optical fiber collimator 7, passes through a band-pass filter 8, and enters an air cavity 11 from an air cavity window 9. After the excitation light incident into the air cavity 11 is absorbed by the gas 14 to be measured, an acoustic pressure wave having an intensity corresponding to the concentration of the gas 14 to be measured in the air cavity 11 is generated. And the acoustic pressure wave that prior art adopted electric capacity microphone or optic fibre mach-zehnder to interfere the absorption and produce is different the utility model discloses in, this acoustic pressure wave is converted into the vibration of vibration diaphragm 151 by the vibration diaphragm 151 of another port department of air cavity 11, and this vibration signal is converted into optical phase signal by low fineness fabry perot interference module 15, reachs the concentration information of gas to be measured 14 through analytic processing. The interference measurement process is that a measurement light signal emitted by a measurement light source 1 driven by a first driving power supply 18 sequentially passes through an optical fiber wave combiner 3, an optical fiber light guide element 4, a transmission optical fiber 5 and an optical fiber wave splitter 6, enters an optical fiber 152 in a low-fineness Fabry-Perot interference module 15, is transmitted to the end face of the optical fiber 152, a small part of light is reflected back to the optical fiber 152 due to the Fresnel effect, while most of light exits to the surface of a vibrating diaphragm 151 and is reflected and then part of light is returned back to the optical fiber 152, and the returned light beam and a light beam directly reflected by the end face of the optical fiber have an optical path difference, so that interference can be generated when a certain phase condition is met. The optical signals reflected from the end surface of the optical fiber 152 and the surface of the vibrating diaphragm 151 are received by the photoelectric detection unit 16 through the optical fiber demultiplexer 6, the transmission optical fiber 5 and the optical fiber light guide element 4, the phase is calculated through the phase demodulation module 17, and the concentration value of the gas to be measured is obtained through analysis by the signal processing and control system 20.
The working principle of the optical fiber acoustic sensor of the utility model is described as follows:
after the excitation light incident into the air cavity 11 is absorbed by the gas 14 to be measured, an acoustic pressure wave p having an intensity corresponding to the concentration of the gas 14 to be measured in the air cavity 11 is generated,
wherein K is a gas and cavity related constant, C p 、C v Respectively the heat capacity at normal pressure and normal volume, c is the concentration of the gas 14 to be measured, I 0 F is the amplitude modulation frequency of the excitation light source 2 for the intensity of light incident on the air cavity.
When the acoustic pressure wave p acts on the diaphragm 151, the deformation of the diaphragm 151 becomes y (p),
where μ, E, a, h are respectively the poisson's ratio, young's modulus of elasticity, radius and thickness of the vibrating membrane 151. The deformation y (p) causes a change in the phase difference of the interference to be delta phi,
where λ is the wavelength of the output optical signal of the measurement light source 1.
The received interference signal caused by the phase difference delta phi is detected by the photo detection unit 16 as,
I m ＝KI m0 [1+γcos(Δφ)] (4)
wherein I is m0 K is a constant and γ is the fringe contrast of the interference signal for the average optical power received by the photodetector 16. The phase difference Δ Φ is obtained by the phase demodulation module 17 according to equation (4). After obtaining Δ φ, the signal processing and control system 20 can calculate and process the concentration of the gas to be measured from the formula (3) and the formula (1)
The measurement light source 1 and the excitation light source 2 are semiconductor lasers (abbreviated as LDs) or superluminescent diodes (abbreviated as SLDs) or Light Emitting Diodes (LEDs). Wherein the excitation light source 2 has a spectrum that covers the absorption peak of the gas 14 to be measured. The spectra of the light beams emitted by the measurement light source 1 and the excitation light source 2 do not overlap.
The first driving power supply 18 supplies a direct current signal to the measurement light source 1. The second drive power supply 19 supplies an ac modulation signal to the excitation light source 2.
The optical fiber combiner 3 and the optical fiber demultiplexer 6 are optical fiber elements for realizing beam combining and splitting, and can be optical fiber couplers or optical fiber multiplexers. The optical fiber light guide element 4 is an optical fiber coupler or an optical fiber circulator with the beam splitting ratio of 1: 1.
The transmission fiber 5 may be a common commercial single-mode fiber or a multi-mode fiber or other fibers suitable for transmitting the optical signals emitted by the measurement light source 1 and the excitation light source 2 with low loss.
The optical fiber collimator 7 is an optical fiber element that emits parallel light.
The band-pass filter 8, which may be an interference filter or other similar functional device, functions to extract a narrow-band optical signal from the light beam emitted from the excitation light source 2, which matches the absorption peak of the gas to be measured. The bandpass filter 8 may not be needed if the excitation light source 2 is a narrow band laser source.
The function of said air cavity window 9 is to transmit the light beam emitted from the excitation light source 2 transparently into the air cavity 11.
The air cavity 11, which is used for containing the gas to be measured and transmitting or enhancing the sound pressure wave, may be tubular, cubic or other.
The gas 14 to be measured is the object of the sensor of the present invention, and can be any gaseous substance having the characteristic of absorbing the light energy emitted from the excitation light source 2, such as methane, carbon dioxide, carbon monoxide, etc.
The fabry-perot interference module 15 with low fineness is the sensitive element of the present invention for measuring the sound pressure wave generated by the light signal absorbed by the gas to be measured 14, which is composed of a vibrating diaphragm 151, an optical fiber 152 and a sleeve 153, and the bonding between the sleeve 153 and the optical fiber 152 can be by gluing (such as epoxy glue) or laser fusing. A certain gap is maintained between the end face of the optical fiber 152 and the inner surface of the vibrating diaphragm 151. The structure and shape of the low-fineness Fabry-Perot interference module 15 and the adopted materials can be optimally designed according to the test environment and the characteristics of sound pressure waves, and the basic principle of the design can follow the related theories of material elasticity mechanics, forced vibration equation of films and plates in media and the like and combine the research results of the propagation characteristics of sound waves in all media.
The photodetection unit 16 functions to convert an optical signal into an electrical signal and amplify the electrical signal, and therefore includes one photodetector, one preamplifier, and the like. The response wavelength of the photodetector should be in the wavelength band of the light signal emitted by the measuring light source 1, and they may be photodiodes, or photocells, etc.
The phase demodulation module 17 is used for obtaining the phase difference change of the low-fineness Fabry-Perot interference module 15 caused by the sound pressure wave generated by the gas absorption light energy.
The signal processing and control system 20 is responsible for controlling the first driving power supply 18 and the second driving power supply 19, and finally provides the concentration information of the gas to be measured according to the computational mathematical model and the processing method established by the measurement principle.
From the foregoing, the utility model has the following characteristics and advantages:
1) The utility model discloses a low fineness optical fiber Fabry-Perot interferes the sound pressure wave signal that the gaseous absorbed light energy of detection produced, interferes the detection method with other two beam optical fibers and compares, and two light beam common light path that low fineness optical fiber Fabry-Perot interfered so the phase drift and the noise that temperature, vibration arouse reduce greatly, and the polarization effect influence has high stability and high sensitivity's advantage moreover.
2) The utility model discloses an all-fiber structure, sensing part constitutes by passive optical device completely moreover, has really integrated photoacoustic gas sensing technique and optical fiber sensing technique advantage between them for this high sensitivity's of photoacoustic gas sensing gas detection technique can be in various strong electromagnetic interference, flammable and explosive abominable occasion application, and can carry out long distance telemetering measurement and multiplexing network deployment constitution sensing network, has greatly expanded photoacoustic gas sensing technique's application and range of application. The advantages of the optical fiber sensing technology are fully exerted.
Drawings
FIG. 1 is a schematic diagram of a method and sensor for photoacoustic gas sensing; the device comprises a measurement light source 1, an excitation light source 2, an optical fiber combiner 3, an optical fiber light guide element 4, a transmission optical fiber 5, an optical fiber wave separator 6, an optical fiber collimator 7, a band-pass filter 8, an air cavity window 9, a sleeve pipe 10, an air cavity 11, an air cavity air inlet 12, an air cavity air outlet 13, gas to be detected 14, a low-fineness Fabry-Perot interference module 15 consisting of a vibrating diaphragm 151, an optical fiber 152 and a sleeve pipe 153, wherein 154 is a sealing ring, a photoelectric detection unit 16, a phase demodulation module 17, a first driving power supply 18, a second driving power supply 19 and a signal processing and control system 20.
Detailed Description
Such as the structure shown in fig. 1. Wherein, the measuring light source 1 adopts a semiconductor laser with the wavelength of 1.55 microns. The excitation light source 2 is an LED with the wavelength of 1.65 microns, and the wavelength band corresponds to the gas absorption peak of methane. The optical fiber wave combiner 3, the optical fiber light guide element 4 and the optical fiber wave separator 6 all adopt optical fiber couplers with the beam splitting ratio of 1: 1. The transmission fiber 5 is a common commercially available single mode fiber. The gas chamber 11 is formed by a circular quartz tube. The air cavity window 9 is made of calcium fluoride glass. The vibrating diaphragm 151 and the sleeve 153 in the low-fineness fabry-perot interference module 15 are made of quartz materials, so that the structural stability of the low-fineness fabry-perot interference module 15 is improved. The photodetection unit 16 employs an InGaAs photodetector. The signal processing and control system 20 is composed of a data acquisition card, a PC and Labview-based software. During measurement, the gas absorbs light energy of the excitation light source 2 to generate a sound pressure wave, the sound pressure wave is converted into vibration of the vibration diaphragm 151, the vibration signal is converted into an optical phase signal by the low-fineness Fabry-Perot interference module 15, the phase difference is obtained by the phase demodulation module 17 according to the formula (4), and then the concentration of the gas to be measured is obtained from the formula (3) and the formula (1) through calculation processing by the signal processing and control system 20. In the embodiment, the measurement is only carried out by taking methane gas detection as an example, the content of 5-10ppm can be measured, and the measurement accuracy reaches within 1%. And the stability and the repeatability of the device are good.
Considering the measurement sensitivity and miniaturization, the resonance frequency of the air cavity 11 is generally designed to be about 1-10 KHz, the diameter of the cavity is generally 4-10 mm, and the length is 30-100 mm; in order to obtain high sensitivity and a large linear measurement range, the reflectivity of the vibrating diaphragm 151 and the reflectivity of the end face of the optical fiber 152 are generally controlled to be less than 40%, and therefore, the end faces of the vibrating diaphragm 151 and the optical fiber 152 may be coated with a reflective film, for example, a gold or aluminum reflective film by an evaporation or sputtering process. The material, thickness and diameter of the vibrating diaphragm 151 determine the acoustic sensitivity and frequency response characteristics thereof, and quartz or silicon wafers are generally selected as the material, with the thickness equal to or less than 5-50 microns and the diameter of 2-5mm.
The optical fiber 152 may be a conventional single mode or multimode fiber with an outer diameter of 125 microns.
It should be noted that the present embodiment is only described by taking methane gas detection as an example, and is not limited to methane measurement. When a broadband excitation light source is used, the corresponding gas can be measured by only changing the center wavelength of the band-pass filter 8 to align the absorption peaks of different gases. When a narrowband excitation light source is adopted, the corresponding gas can be measured only by changing the wavelength of the excitation light source to align with the absorption peaks of different gases. For example, the absorption peak of ethylene is 1532.8nm, that of ammonia is 1544nm, that of carbon monoxide is 1567nm, and that of carbon dioxide is 1572 nm. The same sensitivity and accuracy can be achieved.
In addition, it should be noted that the present invention can be used not only for the measurement of a single gas, but also for the measurement of a plurality of component gases. When the excitation light source 2 is a narrow-band tunable semiconductor laser (or the excitation light source is a broadband light source and the band-pass filter 8 is a tunable filter), the presence of gas with an absorption peak in the tuning range can be measured.
Claims (4)
1. The optical fiber gas sensor comprises a measuring light source (1), an excitation light source (2), an optical fiber combiner (3), a transmission optical fiber (5), an optical fiber wave separator (6), a band-pass filter (8), an air cavity window (9), an air cavity (11) filled with gas to be measured (14), a low-fineness Fabry-Perot interference module (15) consisting of a low-reflection cavity mirror, namely a vibrating diaphragm (151) and a measuring optical fiber (152), a photoelectric detection unit (16), a phase demodulation module (19) and a signal processing and control system (20); adopting a low-reflection cavity mirror and a measuring optical fiber to form an optical fiber Fabry-Perot interferometer; the laser light source (2) is connected with the optical fiber wave combiner (3), the transmission optical fiber (5), the optical fiber wave separator (6) is connected with the band-pass filter (8) and enters the air cavity (11) from the air cavity window (9); exciting light incident into the air cavity (11) is absorbed by the gas to be measured (14), sound pressure waves are generated and converted into vibration of the vibration diaphragm (151) by the vibration diaphragm (151) at the other port of the air cavity (11), and the vibration diaphragm is the low-reflection cavity mirror; the measuring optical signal emitted by the measuring light source (1) is connected with the optical fiber wave combiner (3), the transmission optical fiber (5) and the optical fiber wave splitter (6), enters the measuring optical fiber (152) of the Fabry-Perot interferometer, is transmitted to the end face of the optical fiber (152), and the optical signal reflected from the end face of the optical fiber (152) and the surface of the vibrating diaphragm (151) passes through the optical fiber wave splitter (6), the transmission optical fiber (5) and then passes through the phase demodulation module (17) and the signal processing and control system (20).
2. The optical fiber gas sensor according to claim 1, wherein the resonance frequency of the air chamber (11) is 1 to 10KHz, the diameter of the chamber is 4 to 10mm, and the length is 30 to 100mm.
3. The optical fiber gas sensor according to claim 1, wherein the reflectivity of the diaphragm and the reflectivity of the end face of the optical fiber are 40% or less, and the end faces of the diaphragm and the optical fiber are coated with a reflective film.
4. The fiber gas sensor according to claim 1, wherein the diaphragm is made of quartz or silicon, has a thickness of less than 5-50 μm and a diameter of 2-5mm.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102197284A (en) * | 2008-08-21 | 2011-09-21 | 秦内蒂克有限公司 | Fibre optic acoustic sensing |
| CN103557929A (en) * | 2013-11-14 | 2014-02-05 | 北京航空航天大学 | Optical fiber Fabry-Perot sound pressure sensor manufacturing method based on graphene membrane and measuring method and device thereof |
| CN104266743A (en) * | 2014-10-22 | 2015-01-07 | 中国科学院电子学研究所 | Wavelength modulation optical fiber acoustic sensor |
| CN104280340A (en) * | 2014-10-28 | 2015-01-14 | 山西大学 | Device and method for detecting gas based on LED light source and by adopting electrical modulation phase elimination way |
| CN106248602A (en) * | 2016-09-19 | 2016-12-21 | 电子科技大学 | Hydrogen sulfide gas sensing device based on optical fiber F P interferometer |
| CN107121220A (en) * | 2017-05-25 | 2017-09-01 | 杭州电子科技大学 | Optics Fabry-Perot-type cavity air pressure sensing system |
| TWI735466B (en) * | 2015-09-29 | 2021-08-11 | 挪威商新泰夫提圖股份有限公司 | Noise canceling detector |
| CN114965285A (en) * | 2022-05-11 | 2022-08-30 | 重庆邮电大学 | Photoacoustic spectrum detection system based on acoustic wave direct coupling-multi-optical-path photoacoustic cell |
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2007
- 2007-04-04 CN CNU2007200365415U patent/CN201034929Y/en not_active Expired - Lifetime
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102197284A (en) * | 2008-08-21 | 2011-09-21 | 秦内蒂克有限公司 | Fibre optic acoustic sensing |
| CN102197284B (en) * | 2008-08-21 | 2016-10-26 | 光学感应器控股有限公司 | fibre optic acoustic sensing |
| CN103557929B (en) * | 2013-11-14 | 2015-11-11 | 北京航空航天大学 | A kind of Fabry-perot optical fiber sound pressure sensor method for making based on graphene film and measuring method, device |
| CN103557929A (en) * | 2013-11-14 | 2014-02-05 | 北京航空航天大学 | Optical fiber Fabry-Perot sound pressure sensor manufacturing method based on graphene membrane and measuring method and device thereof |
| CN104266743B (en) * | 2014-10-22 | 2018-06-22 | 中国科学院电子学研究所 | Wavelength modulation optical fiber sonic transducer |
| CN104266743A (en) * | 2014-10-22 | 2015-01-07 | 中国科学院电子学研究所 | Wavelength modulation optical fiber acoustic sensor |
| CN104280340B (en) * | 2014-10-28 | 2016-08-03 | 山西大学 | The gas detection apparatus based on LED light source and using electricity modulation phase resolving therapy and method |
| CN104280340A (en) * | 2014-10-28 | 2015-01-14 | 山西大学 | Device and method for detecting gas based on LED light source and by adopting electrical modulation phase elimination way |
| TWI735466B (en) * | 2015-09-29 | 2021-08-11 | 挪威商新泰夫提圖股份有限公司 | Noise canceling detector |
| CN106248602A (en) * | 2016-09-19 | 2016-12-21 | 电子科技大学 | Hydrogen sulfide gas sensing device based on optical fiber F P interferometer |
| CN106248602B (en) * | 2016-09-19 | 2019-09-03 | 电子科技大学 | Hydrogen sulfide gas sensing device based on fiber F-P interferometer |
| CN107121220A (en) * | 2017-05-25 | 2017-09-01 | 杭州电子科技大学 | Optics Fabry-Perot-type cavity air pressure sensing system |
| CN114965285A (en) * | 2022-05-11 | 2022-08-30 | 重庆邮电大学 | Photoacoustic spectrum detection system based on acoustic wave direct coupling-multi-optical-path photoacoustic cell |
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