CN110617912B - Gas pressure monitoring system based on optical fiber white light interferometry - Google Patents
Gas pressure monitoring system based on optical fiber white light interferometry Download PDFInfo
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
- G01L11/02—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means
- G01L11/025—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means using a pressure-sensitive optical fibre
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Abstract
The invention provides a gas pressure monitoring system based on an optical fiber white light interferometry technology, which comprises a white light interferometer demodulator, an optical fiber topology network and a gas pressure sensor group, wherein the white light interferometer demodulator is connected with the optical fiber topology network; the white light interference demodulator comprises a white light source, a first optical fiber circulator, a second optical fiber circulator, a first optical fiber half-reflecting mirror, a first self-focusing lens, a stepping motor, a data acquisition card, a photoelectric detector and a computer; the optical fiber topology network is formed by connecting optical switches or multi-path splitters in a tree structure; the air pressure sensor group comprises a plurality of same air pressure sensors, and each air pressure sensor comprises an elastic membrane, a reflective coating, a sensor shell, standard air pressure inert gas, transparent glass, a second optical fiber half-reflecting mirror and a second self-focusing lens. The gas pressure monitoring system based on the optical fiber white light interferometry provided by the invention adopts the optical sensor to monitor the gas pressure in the pressure container, and is more suitable for monitoring the pressure of the gas pressure container under severe conditions.
Description
Technical Field
The invention belongs to the technical field of optical fiber sensing, and particularly relates to a gas pressure monitoring system based on an optical fiber white light interferometry technology.
Background
The gas pressure monitoring is one of important monitoring contents in industrial engineering safety monitoring, and is widely applied to absolute height monitoring, gas pressure monitoring inside a gas pressure container, leakage-proof monitoring of a gas storage container and the like. In the problem of monitoring the air pressure of the pressure vessel in the environment of high temperature, strong acid and alkali and strong electromagnetic field, the performance of the pressure vessel is reduced because the natural aging and corrosion speed of the vessel is high, the compressive strength of a corrosion point is reduced, or the air tightness is reduced. Therefore, the monitoring of the internal gas pressure of the gas pressure container and the monitoring of the leakage prevention of the gas storage container have important industrial engineering value and significance.
At present, the internal gas pressure of a gas pressure container is monitored, and the leakage prevention monitoring of a gas storage container mainly adopts an electrical sensor, such as: capacitive sensors, resistive strain gauge sensors, inductive sensors, and the like. The electrical sensor has the general characteristics of low system cost, good stability, good compatibility and convenient operation. However, because the sensor is the essential characteristic of an electrical device, the electrical sensor generally has poor anti-electromagnetic interference capability; the paint is not resistant to acid and alkali corrosion; the self structure is electrified, so that the problems of potential safety hazards and the like exist; the pressure monitoring device can not be used for monitoring the pressure of a container with high temperature, high voltage, strong electromagnetic field, flammability, explosiveness and strong corrosive gas.
Disclosure of Invention
The invention aims to solve the problem that the gas pressure in the strong electromagnetic field environment is difficult to measure in the prior art.
The invention provides a gas pressure monitoring system based on an optical fiber white light interferometry technology, which adopts an optical sensor to monitor the internal gas pressure of a pressure container, and the optical sensor has the characteristics of acid and alkali corrosion resistance, high temperature resistance and electromagnetic interference resistance; the sensor is not electrified, has no potential safety hazard and the like, and is more suitable for pressure monitoring of the gas pressure container under severe conditions.
The invention adopts the following technical scheme:
a gas pressure monitoring system based on an optical fiber white light interferometry technology comprises a white light interferometer demodulator, an optical fiber topology network and an air pressure sensor group;
the white light interference demodulator comprises a white light source, a first optical fiber circulator, a second optical fiber circulator, a first optical fiber half-reflecting mirror, a first self-focusing lens, a stepping motor, a data acquisition card, a photoelectric detector and a computer; the white light source is arranged at a first port of the first optical fiber circulator, a second port of the first optical fiber circulator is connected with an input end of the first optical fiber half-reflecting mirror, an output end of the first optical fiber half-reflecting mirror is connected with the first self-focusing lens, an air optical path is formed between the first self-focusing lens and the reflecting mirror, the reflecting mirror is fixed on the stepping motor, the stepping motor is controlled by a computer, a third port of the first optical fiber circulator is connected with a first port of the second optical fiber circulator, a second port of the second optical fiber circulator is connected with an optical fiber topology network, and a third port of the second optical fiber circulator is connected with a photoelectric detector and a data acquisition card;
the optical fiber topology network is formed by connecting optical switches or multi-path splitters in a tree structure, the input end of a first-stage multi-path splitter or optical switch is connected with a second port of a second optical fiber circulator, the output end of a previous-stage multi-path splitter or optical switch is respectively connected with the input end of a next-stage multi-path splitter or optical switch, and the last-stage multi-path splitter or optical switch is connected with the air pressure sensor;
the air pressure sensor group comprises a plurality of same air pressure sensors, and each air pressure sensor comprises an elastic membrane, a reflective coating, a sensor shell, standard air pressure inert gas, transparent glass, a second optical fiber half-reflecting mirror and a second self-focusing lens; the utility model discloses a sensor, including sensor shell, elastic membrane, sensor, second optic fibre half-reflecting mirror, elastic membrane fixes on sensor shell, reflective coating has been plated to the elastic membrane inboard, two upper and lower cavities are divided into to the sensor inside, two upper and lower cavities by clear glass separates, the second is fixed in sensor shell bottom and perpendicular with the reflective coating of elastic membrane inboard from focusing lens, the output of second optic fibre half-reflecting mirror with the second is connected from focusing lens, the input and the n level multichannel branching unit or the photoswitch of second optic fibre half-reflecting mirror are connected.
Further, the white light source is a white light source with a central wavelength of 1310 nm.
Furthermore, the upper chamber inside the sensor is filled with inert gas with standard air pressure, and the lower chamber inside the sensor is filled with standard gas.
Further, the air pressure sensor is fixed in the environment to be measured in an adhesion or mechanical fixing mode.
Further, the stepping motor is a stepping motor capable of completing a linear scanning process.
The working principle of the technical scheme is as follows: light emitted by a white light source with the central wavelength of 1310nm is directly coupled into a first port of the first optical fiber circulator and emitted from a second port; the light emitted from the second port is coupled into the first optical fiber semi-reflecting mirror, and the light is divided into two parts in proportion after entering the first optical fiber semi-reflecting mirror. Where a portion of the light is reflected back to port two of the first fiber optic circulator. Another portion of the light is transmitted into the first self-focusing lens and emitted. The emitted light is reflected by the reflector and then returns to the second port of the first optical fiber circulator through the first self-focusing lens and the first optical fiber semi-reflecting mirror. Two parts of light are coupled into a first port of a second optical fiber circulator from a third port of the first optical fiber circulator, are emitted out from a second port of the second optical fiber circulator, are coupled into an optical fiber topology network, and are coupled into the air pressure sensor through the optical fiber topology network. In the barometric sensor, light passes through the second fiber half-reflecting mirror, then one part of the light is reflected and coupled back to the fiber topology network, the other part of the light is transmitted and emitted through the second self-focusing lens, one part of emitted light is reflected by transparent glass, the other part of the light is reflected by the reflective coating on the inner side of the elastic membrane after being transmitted, and finally the two parts of the light are re-coupled back to the second self-focusing lens and are coupled back to the fiber topology network through the second self-focusing lens and the second fiber half-reflecting mirror in sequence. And the light coupled back to the optical fiber topology network passes through the second port of the second optical fiber circulator, reaches the third port of the second optical fiber circulator and finally enters the photoelectric detector. After the photoelectric detector completes photoelectric conversion, the electric signal is collected by the data acquisition card and input to the computer, and the computer outputs a calculation result after operation to complete the measurement process.
The invention has the beneficial effects that:
(1) the optical fiber device is used as a main measuring element of the air pressure sensor, so that the strong electromagnetic field can be immunized, the acid-base corrosion resistance is better, the splitting ratio of the transmitted light and the reflected light is well controlled, the influence of the optical fiber on the measurement is eliminated, and the influence of environmental factors on the measurement is greatly reduced.
(2) By introducing the first optical fiber half-reflecting mirror and the second optical fiber half-reflecting mirror, the structure of the traditional Michelson interferometer is optimized, the influence of factors such as the length of the optical fiber, the external temperature and the length of the connecting optical fiber on the measurement result is eliminated, and long-span remote measurement is realized.
(3) The air pressure sensor can adjust the standard air pressure value filled in the air pressure sensor according to the intensity of the measured air pressure, and different measurement accuracy and measurement ranges can be realized by changing the intensity of the elastic membrane.
(4) The optical fiber topology network is introduced, multi-point measurement based on a plurality of air pressure sensors is realized, and the optical fiber topology network has the advantages of simple structure, stable performance, strong environmental adaptability and the like.
Drawings
Fig. 1 is a schematic diagram of the general structure of a gas pressure monitoring system based on the optical fiber white light interferometry.
Fig. 2 is a schematic diagram of optical path measurement in the present invention.
Fig. 3 is a schematic structural diagram of the air pressure sensor according to the present invention.
In the attached drawing, a white light source 1, a first optical fiber circulator 2, a first optical fiber half-reflecting mirror 3, a first self-focusing lens 4, a reflecting mirror 5, a stepping motor 6, a second optical fiber circulator 7, an optical fiber topology net 8, a second optical fiber half-reflecting mirror 9, a second self-focusing lens 10, transparent glass 11, a reflective coating 12, a photoelectric detector 13, an elastic membrane 14, a sensor shell 15 and inert gas 16 with standard air pressure.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, the present invention provides a gas pressure monitoring system based on optical fiber white light interferometry, which includes an optical interference demodulator, an optical fiber topology network 8 and a gas pressure sensor group;
the white light interference demodulator comprises a white light source 1, a first optical fiber circulator 2, a second optical fiber circulator 7, a first optical fiber half-reflecting mirror 3, a reflecting mirror 5, a first self-focusing lens 4, a stepping motor 6, a data acquisition card, a photoelectric detector 13 and a computer; the white light source 1 is a white light source 1 with a central wavelength of 1310nm, the white light source 1 is arranged at a first port of a first optical fiber circulator 2, a second port of the first optical fiber circulator 2 is connected with an input end of a first optical fiber half-reflecting mirror 3, an output end of the first optical fiber half-reflecting mirror 3 is connected with a first self-focusing lens 4, an air optical path is formed between the first self-focusing lens 4 and a reflecting mirror 5, the reflecting mirror 5 is fixed on a stepping motor 6 capable of completing a linear scanning process, the stepping motor 6 is controlled by a computer, a third port of the first optical fiber circulator 2 is connected with a first port of a second optical fiber circulator 7, a second port of the second optical fiber circulator 7 is connected with an optical fiber topology network 8, and a third port of the second optical fiber circulator 7 is connected with a photoelectric detector 13 and a data acquisition card;
the optical fiber topology network 8 is formed by an optical switch or a multi-path splitter and is connected in a tree structure, the optical fiber topology network 8 can be divided into a first-stage network or a multi-stage network, wherein the first-stage optical fiber topology network can be completed by one optical switch or multi-path splitter; the multilevel optical fiber topology network can be built by cascade connection of a plurality of first-level optical fiber topology networks, and the switching of network ports is controlled by a computer. Such as: the input end of the first-level multi-path branching device or the optical switch is connected with the second port of the second optical fiber circulator 7, the output end of the first-level multi-path branching device or the optical switch is respectively connected with the input end … … of the second-level multi-path branching device or the optical switch, and so on, the output end of the last (n-1) -level multi-path branching device or the optical switch is respectively connected with the input end of the n-level multi-path branching device or the optical switch, and the n-level multi-path branching device or the optical switch;
the air pressure sensor group comprises a plurality of same air pressure sensors, and the air pressure sensors are fixed in an environment to be measured in an adhesion or mechanical fixing mode; the air pressure sensor comprises an elastic membrane 14, a reflective coating 12, a sensor shell 15, standard air pressure inert gas, transparent glass 11, a second optical fiber half-mirror 9 and a second self-focusing lens 10; the elastic membrane 14 is fixed on the sensor shell 15, the inner side of the elastic membrane 14 is plated with the reflective coating 12, the sensor is internally divided into an upper cavity and a lower cavity, the upper cavity inside the sensor is filled with inert gas 16 with standard air pressure, the lower cavity inside the sensor is filled with standard gas, the upper cavity and the lower cavity are separated by transparent glass 11, the second self-focusing lens 10 is fixed at the bottom of the sensor shell 15 and is perpendicular to the reflective coating 12 on the inner side of the elastic membrane 14, when the external air pressure changes, the elastic membrane 14 is pressed to deform, the distance between the second self-focusing lens 10 and the reflective coating 12 changes, and the sensing process is completed. The output end of the second optical fiber half-reflecting mirror 9 is connected with a second self-focusing lens 10, and the input end of the second optical fiber half-reflecting mirror 9 is connected with an n-stage multipath splitter or an optical switch.
The specific implementation process of this embodiment is as follows:
based on the white light Michelson interference principle, when the optical paths of the two lights are equal, coherence occurs. By detecting the light intensity change, whether the two paths of light are coherent or not can be judged, and when the two paths of light are coherent, namely whether the two paths of light have equal optical paths or not can be judged.
First, the optical path is defined as follows:
sensing optical distance A: the optical path from the second fiber half mirror 9 to the reflective coating 12;
reference optical length B: the optical path from the second fiber half mirror 9 to the transparent glass 11;
a guide optical length C: the optical path from the first fiber half mirror 3 to the second fiber half mirror 9;
demodulation optical length D: the optical path from the first fiber half mirror 3 to the mirror 5;
measurement of optical length a:
optical path a + optical path C ═ optical path C + optical path D
When the two paths of light pass through the optical path A, C and the optical path C, D respectively, the stepping motor 6 performs scanning movement, changes the length of the demodulation optical path D, and makes the demodulation optical path D equal to the sensing optical path a to obtain a coherent signal, i.e. completing the measurement of the optical path a. When the sensing optical path length a changes, the demodulation optical path length D will also change accordingly. Since both sides of the equation contain the optical path length C, the length of the optical path length C does not affect the measurement, and it is this characteristic that provides a guarantee for the long-distance measurement, so that the optical fiber can be arbitrarily extended without causing errors to the measurement.
The measurement principle of the reference optical path B is the same as that of the sensing optical path a.
The reference optical path B is used for providing reference for measurement of the sensing optical path A, and errors caused by factors such as motor operation stability and spectral distortion are eliminated by making a difference between the optical paths A and B.
Pressure variation is converted into optical path variation:
when the pressures inside and outside the air pressure sensor are equal, the elastic membrane is in a free position, when the external pressure is increased, the optical path A is reduced, and when the external pressure is reduced, the optical path A is increased. Through calibration, the corresponding relation between the stable pressure and the optical path can be obtained, and further the air pressure measurement is completed.
The measuring system can also adjust the air pressure value filled in the air pressure sensor according to the intensity of the measured air pressure, and different measuring precision and measuring range can be realized by changing the intensity of the elastic membrane.
The beneficial effect of this embodiment does:
(1) the optical fiber device is used as a main measuring element of the air pressure sensor, so that the strong electromagnetic field can be immunized, the acid-base corrosion resistance is better, the splitting ratio of the transmitted light and the reflected light is well controlled, the influence of the optical fiber on the measurement is eliminated, and the influence of environmental factors on the measurement is greatly reduced.
(2) By introducing the first optical fiber half-reflecting mirror and the second optical fiber half-reflecting mirror, the structure of the traditional Michelson interferometer is optimized, the influence of factors such as the length of the optical fiber, the external temperature and the length of the connecting optical fiber on the measurement result is eliminated, and long-span remote measurement is realized.
(3) The air pressure sensor can adjust the standard air pressure value filled in the air pressure sensor according to the intensity of the measured air pressure, and different measurement accuracy and measurement ranges can be realized by changing the intensity of the elastic membrane.
(4) The optical fiber topology network is introduced, multi-point measurement based on a plurality of air pressure sensors is realized, and the optical fiber topology network has the advantages of simple structure, stable performance, strong environmental adaptability and the like.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art; the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; these modifications and substitutions do not cause the essence of the corresponding technical solution to depart from the scope of the technical solution of the embodiments of the present invention, and are intended to be covered by the claims and the specification of the present invention.
Claims (5)
1. A gas pressure monitoring system based on an optical fiber white light interferometry technology is characterized by comprising a white light interferometer demodulator, an optical fiber topology network and an air pressure sensor group;
the white light interference demodulator comprises a white light source, a first optical fiber circulator, a second optical fiber circulator, a first optical fiber half-reflecting mirror, a first self-focusing lens, a stepping motor, a data acquisition card, a photoelectric detector and a computer; the white light source is arranged at a first port of the first optical fiber circulator, a second port of the first optical fiber circulator is connected with an input end of the first optical fiber half-reflecting mirror, an output end of the first optical fiber half-reflecting mirror is connected with the first self-focusing lens, an air optical path is formed between the first self-focusing lens and the reflecting mirror, the reflecting mirror is fixed on the stepping motor, the stepping motor is controlled by a computer, a third port of the first optical fiber circulator is connected with a first port of the second optical fiber circulator, a second port of the second optical fiber circulator is connected with an optical fiber topology network, and a third port of the second optical fiber circulator is connected with a photoelectric detector and a data acquisition card;
the optical fiber topology network is formed by connecting optical switches or multi-path splitters in a tree structure, the input end of a first-stage multi-path splitter or optical switch is connected with a second port of a second optical fiber circulator, the output end of a previous-stage multi-path splitter or optical switch is respectively connected with the input end of a next-stage multi-path splitter or optical switch, and the last-stage multi-path splitter or optical switch is connected with the air pressure sensor;
the air pressure sensor group comprises a plurality of same air pressure sensors, and each air pressure sensor comprises an elastic membrane, a reflective coating, a sensor shell, standard air pressure inert gas, transparent glass, a second optical fiber half-reflecting mirror and a second self-focusing lens; the utility model discloses a sensor, including sensor shell, elastic membrane, sensor, second optic fibre half-reflecting mirror, elastic membrane fixes on sensor shell, reflective coating has been plated to the elastic membrane inboard, two upper and lower cavities are divided into to the sensor inside, two upper and lower cavities by clear glass separates, the second is fixed in sensor shell bottom and perpendicular with the reflective coating of elastic membrane inboard from focusing lens, the output of second optic fibre half-reflecting mirror with the second is connected from focusing lens, the input and the n level multichannel branching unit or the photoswitch of second optic fibre half-reflecting mirror are connected.
2. The system of claim 1, wherein the white light source is a 1310nm centered white light source.
3. The system of claim 1, wherein the upper chamber of the sensor is filled with inert gas with standard pressure, and the lower chamber of the sensor is filled with standard gas.
4. The system of claim 1, wherein the pressure sensor is fixed in the environment to be measured by means of bonding or mechanical fixing.
5. The system of claim 1, wherein the step motor is a step motor capable of performing a linear scanning process.
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| CN111239068B (en) * | 2020-03-16 | 2022-12-02 | 北京微芯边缘计算研究院 | Water quality sensing device based on adjustable optical path of absorption spectroscopy |
| CN114964029B (en) * | 2022-05-25 | 2023-05-30 | 重庆文理学院 | Shaft torsion detecting system based on optical fiber measuring technology |
| CN116007826A (en) * | 2023-01-17 | 2023-04-25 | 福州大学 | Optical fiber pressure measuring instrument based on broadband light interference and water pressure measuring method |
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