CN102829902A - Array-type multi-channel fiber-process Fabry-Perot pressure sensor and pressure measurement method - Google Patents

Abstract

The invention discloses an array type multi-channel optical fiber percol pressure sensing device and a pressure measurement method. An LED light source array (3) composed of an LED light source modulation module (1) and an LED light source (2) is sequentially arranged from the input end to the output end. ), fiber optic coupler array (5) composed of fiber optic coupler (4), fiber optic Fab sensor array (7), fiber optic array (8), optical wedge (9), linear array A demodulation optical path module composed of a CCD (10) and a signal processing unit (11). Compared with the prior art, the combination of LED light source array modulation and optical fiber array structure of the present invention realizes the sequential and fast demodulation of multiple optical fiber F-P pressure sensors by a single demodulation optical path. The problem of loss and high reliability; and the channel expansion is easy, so that the sensing channel can reach up to 64 channels.

Description

Array type multi-channel optical fiber Fabry pressure sensor device and pressure measurement method

technical field

The invention relates to the field of optical fiber sensing, in particular to an array type multi-channel optical fiber Fabry pressure sensing device based on LED light source modulation and a pressure measurement method thereof.

Background technique

The fiber optic Fabry pressure sensor usually consists of a Fabry-Perot microresonator cavity formed by the end face of an optical fiber and the end face of a diaphragm. The pressure acts on the diaphragm to deform the diaphragm, resulting in a change in the length of the Fabry cavity, thereby realizing sensing. Due to such structural characteristics, the fiber optic Fabry pressure sensor cannot realize series wavelength division multiplexing like fiber gratings, and its multi-channel realization needs to be switched by optical switches. Optical switches are commonly used in optical switching systems in optical fiber transmission, and are widely used in multi-channel optical fiber sensing systems. Optical switches can be divided into two categories: mechanical and non-mechanical. Mechanical optical switches are moved by optical fibers or optical components to change the optical path to achieve channel switching. The advantages are low insertion loss, high isolation, and no polarization. And wavelength, the disadvantage is that the switching time is long, the optical power jitters at the moment of switching, the number of switching is limited, and the repeatability is poor. Non-mechanical optical switches rely on electro-optical effects, magneto-optic effects, acousto-optic effects, and thermo-optic effects to change the refractive index of the waveguide and change the optical path. The advantage of this type of optical switch is that the switching time is short, which can reach milliseconds or even shorter, but Due to the limitation of the optical characteristics of the device material, the spectral working spectrum is usually narrow, and it cannot work in the visible light band.

Contents of the invention

Based on the problems existing in the above-mentioned prior art, the present invention proposes a novel array type multi-channel fiber optic sensor pressure sensing device and pressure measurement method, and constructs an arrayed fiber optic sensor array through an array of LED light sources The structure of the channel sensing device can quickly modulate each LED light source, and realize the sequential demodulation of multiple optical fiber FAP pressure sensors by a single demodulation optical path, achieving high-speed switching, low loss, high reliability, and multi-channel optical fiber FAP sensing Purpose.

The present invention proposes an array type multi-channel optical fiber Perot pressure sensing device, the device is sequentially provided with an LED light source modulation module 1, an LED light source array 3 composed of an LED light source 2, and an optical fiber coupler 4 from the input to the output end. Fiber optic coupler array 5, fiber optic Fab sensor array 7 composed of fiber optic Fab sensor 6, optical fiber array 8, optical wedge 9, demodulation optical path module and signal processing unit 11 composed of linear array CCD10, wherein:

The LED light source array 3 is used to provide a broadband light source for sensing and detection;

The LED light source modulation module 1 is used to generate the LED light source modulation signal, and switch each LED light source according to the modulation signal, so that each LED light source in the LED light source array emits light and goes out sequentially;

The optical fiber Fab sensor array 7 is used to sense the change of external pressure and convert the pressure into Fab cavity information, and different pressures correspond to different Fab cavity lengths;

Fiber optic coupler array 5: used to introduce the light emitted by the LED light source array into the fiber optic Fab sensor array, and introduce the light returned by the fiber optic Fap sensor array into the demodulation optical path module;

The demodulation optical circuit module is used to receive the optical signal returned by the fiber coupler array, and convert the low-coherence interference signal into an electrical signal, wherein the optical fiber array 8 guides the signal returned by the fiber coupler array into the demodulation optical circuit in parallel;

Signal processing unit; based on an embedded system or computer, it is used to extract cavity length information from electrical signals and correspond to pressure measurement results;

An LED light source 2, a fiber optic sensor 6 and a fiber coupler 4 form a pressure sensing channel, and the sensing signal of each pressure sensing channel is calibrated in advance, and the sensor signal calibration value is the channel fiber optic sensor. The corresponding relationship between the length of the sensor cavity and the positions of the interference fringes collected by the linear array CCD10 in the demodulation optical path serves as the demodulation basis for the signal processing unit 11 .

The optical fiber output ends 12 of the optical fiber array 8 are arranged in a certain lattice shape, including a single-row one-word lattice arrangement structure, a double-row lattice arrangement structure, and a multi-row lattice or circular lattice arrangement structure.

The LED light source modulation module 1 outputs modulation signals with a modulation frequency of 10 Hz to 40 kHz.

The number of channels is designed to be 3 to 64 channels.

The fiber coupler is a 1×2 multimode fiber coupler, and the fiber specifications include 50/125 μm, 62.5/125 μm, 80/125 μm or 100/125 μm.

A method for measuring pressure using an arrayed multi-channel optical fiber Fabry pressure sensing device, the method includes the following steps;

Step 1. An LED light source 2, an optical fiber sensor 6 and an optical fiber coupler 4 are used to form a pressure sensing channel, and the sensing signal of each pressure sensing channel is calibrated in advance. The sensing signal calibration value is the The corresponding relationship between the cavity length of the channel optical fiber F-P sensor and the position of the interference fringes collected by the linear array CCD10 in the demodulation optical path is used as the demodulation basis of the signal processing unit 11 .

Step 2: Collect and process, that is, the LED light source modulation module 1 generates an LED light source modulation signal, so that one LED light source 2 in the LED light source array 3 emits light at a certain moment, and other LED light source 2 has no light output; The light reaches the fiber optic sensor 6 through the fiber optic coupler 4 connected to it, so that the pressure signal is modulated into an optical signal; the light signal is introduced into the corresponding optical fiber in the optical fiber array 8 through the optical fiber coupler 6 again, and is output through the optical fiber of the optical fiber array 8 Terminal 12 enters the demodulation optical path module;

Step 3, the optical signal forms spatial low-coherence interference fringes through the optical wedge 9 of the demodulation optical path module, and is received by the linear array CCD 10, and the signal output of the linear array CCD is synchronized with the modulation signal of the LED light source;

Step 4, the signal processing unit 11 processes the interference fringe signal output by the linear array CCD 10, extracts the Farpert cavity signal therefrom, and corresponds to the pressure measurement result according to the calibration data;

Step 5. Repeat the above steps 2 to 4 until the pressure of all channels is demodulated.

Compared with the prior art, the LED light source array modulation adopted in the present invention combined with the fiber array structure realizes a single demodulation optical path to quickly demodulate the order of multiple fiber-optic F-P pressure sensors, which overcomes the inability of the traditional optical switch structure to simultaneously meet high-speed switching, low loss and high reliability; in addition, the LED fast modulation method proposed by the present invention greatly improves the switching speed of the sensing channel, which can reach 40kHz. And the channel expansion is easy, so that the sensing channel can reach 64 channels at most.

Description of drawings

Fig. 1 is a schematic structural diagram of an arrayed multi-channel optical fiber Fabry pressure sensing device;

Figure 2 is a schematic diagram of an optical fiber array,

Among them: a, is a single-row one-word lattice fiber array structure; b, is a double-row lattice fiber array structure; c, is a four-row lattice fiber array structure; d, is a circular lattice fiber array structure;

Fig. 3 is a modulation response signal diagram of a white LED light source at a modulation frequency of 10 kHz;

In Figure 1:

1. LED light source modulation module 2. LED light source 3. LED light source array 4. Fiber optic coupler 5. Fiber optic coupler array 6. Fiber optic FAP sensor 7. Fiber FAP sensor array 8. Fiber array 9. Optical wedge 10. Wire Array CCD 11. Signal processing unit

In Figure 2:

12. Optical fiber output port

In Figure 3:

13. Response waveform of LED light source, 14. Output voltage of drive circuit, 15. Modulation voltage

Detailed ways

The specific implementation, structure, features and effects provided by the present invention will be described in detail below in conjunction with the accompanying drawings and preferred embodiments.

As shown in Figure 1, the array type multi-channel fiber optic FAP pressure sensing device includes: LED light source modulation module 1, LED light source array 3 composed of LED light source 2, fiber optic coupler array 5 composed of fiber coupler 4, fiber optic FAP The sensor 6 consists of an optical fiber Fab sensor array 7 , an optical fiber array 8 , an optical wedge 9 , a linear array CCD 10 and a signal processing unit 11 . Wherein, the optical fiber output ends 12 of the optical fiber array 8 are arranged in a certain lattice shape, including a single-row dot matrix structure, a double-row dot matrix structure, a multi-row dot matrix structure or a circular dot matrix structure, as shown in FIG. 2 .

An LED light source 2, an optical fiber Fab sensor 6 and an optical fiber coupler 4 form a pressure sensing channel. Firstly, the sensing signal is calibrated for each pressure sensing channel, that is, the cavity length and The corresponding relationship of the positions of the interference fringes collected by the linear array CCD10 in the demodulation optical path is used as the demodulation basis of the signal processing unit 11 .

The array type multi-channel optical fiber method for measuring the Perkin pressure includes the following steps: during acquisition and processing, the LED light source modulation module 1 generates an LED light source modulation signal, so that one LED light source 2 in the LED light source array 3 emits light at a certain moment, and the other LED light source 2 There is no light output, and the light output by the LED light source 2 of this road reaches the optical fiber Fab sensor 6 through the optical fiber coupler 4 connected thereto, so that the pressure signal is modulated into an optical signal. The modulated optical signal is introduced to the corresponding optical fiber in the optical fiber array 8 through the optical fiber coupler 6 again, and enters the demodulation optical circuit module through the optical fiber output end 12 of the optical fiber array 8 . In the demodulation optical path module, the optical signal forms spatial low coherence interference fringes through the optical wedge 9 and is received by the linear array CCD10, and the output of the linear array CCD signal is synchronized with the modulation signal of the LED light source. The signal processing unit 11 processes the interference fringe signal output by the linear array CCD 10 , extracts the Fappel cavity signal therefrom, and corresponds to the pressure information according to the calibration data.

The LED light source modulation module 1 outputs a modulation signal with a modulation frequency of 10 Hz to 40 kHz, and each LED light source 2 in the LED light source array 3 switches according to the modulation signal, and turns on and off sequentially. The linear array CCD 10 synchronously collects the low-coherence interference fringe signal generated by the pressure sensing channel where the LED light source 2 is located, and demodulates the pressure information corresponding to the pressure sensing channel through the signal processing unit 11 . Therefore, the signal processing unit 11 sequentially demodulates the pressure information corresponding to each pressure sensing channel according to the modulation signal output by the LED light source modulation module 1, and realizes the arrayed multi-channel optical fiber Fabry pressure sensing based on LED light source modulation.

Specific embodiments of the present invention are described as follows:

What is exemplified in this embodiment is a multi-channel fiber optic Fabry pressure sensing device composed of 12 pressure sensing channels. The LED light source modulation module 1 adopts a voltage modulation frequency of 10 kHz to modulate the 12-way white LED light source 2. The light source The modulation response is shown in Figure 3. Due to the fast response of the LED light source, fast switching speed, and stable signal, when the voltage modulation frequency is 10kHz, the response waveform 13 of the white LED light source is a complete square wave, which is synchronized with the output voltage 14 of the driving circuit and the modulation voltage 15, and has very good response characteristics. .

A white light LED light source 2, a fiber optic F-P sensor 6 and a fiber coupler 4 constitute a pressure sensing channel. Firstly, the sensing signals of the 12 pressure sensing channels are calibrated respectively, and the cavity length and solution of the F-P sensor of the channel are obtained. The corresponding relationship of the positions of the interference fringes collected by the linear array CCD10 in the light adjustment path is used as the demodulation basis of the signal processing unit 11 .

During acquisition and processing, only the white light LED light source 2 of one pressure sensing channel is turned on at each moment, and there is an optical path difference 2d in the reflected light of the two end faces of the optical fiber Fab sensor 6 on this channel, where d is the distance between the two end faces . The two reflected lights form an optical modulation signal, which is coupled into the optical fiber and reaches the optical fiber output end 12 of the optical fiber array 8 through the optical fiber coupler 4. The light emitted from the optical fiber output end 12 passes through the optical wedge 9 and reaches the linear array CCD10. When the optical path difference produced by the optical fiber Fab sensor 6 and the optical wedge 9 matches, the corresponding area of the linear array CCD 10 will produce obvious interference fringes. The signal processing unit 11 processes the interference fringes collected by the linear array CCD 10 according to the calibration data of the pressure sensing channel, and demodulates to obtain the cavity length 2d of the Farpert cavity, and then obtains the pressure value corresponding to the cavity length 2d.

When the LED light source modulation module 1 completes the output of a group of 12 light source signals, the signal processing system correspondingly completes the demodulation of the group of 12 light modulation signals. The light source modulation module 1 adopts a voltage modulation frequency of 10kHz, and it only takes 0.1 milliseconds to collect and demodulate the signals of each fiber-optic sensor 6, and only 1.2 milliseconds to collect and demodulate a group of 12 sensing signals.

By analyzing the distribution probability of the 12 channels of demodulation data, according to the relationship between system faults and distribution probability, and the fault detection model established by the theory of multi-sensor data fusion, the self-test of the sensor can be realized by the detector. For a system using a single-channel optical fiber sensor channel, the probability of demodulation result failure is 5% due to the divergence of the pressure algorithm caused by the abnormal signal of the sensor. Using the system with 12 optical fiber sensor channels, through the fault detection model, the probability of the failure of the entire system due to signal abnormalities in more than 3 sensors at the same time is reduced to 0.0052%, which greatly improves the stability and reliability of the system.

Claims (6)

1. array multichannel optical fiber method amber pressure sensor device; It is characterized in that; This device is provided with demodulation light path module and the signal processing unit (11) that led light source array (3) that led light source modulation module (1), led light source (2) constitute, fibre coupler arrays (5) that fiber coupler (4) constitutes, optical fiber Fabry-Perot sensor array (7), fiber array (8), wedge (9), line array CCD (10) that optical fiber Fabry-Perot sensor (6) constitutes constitute in regular turn from being input to output terminal, wherein:

Led light source array (3) is used to provide the sensing detection wideband light source;

Led light source modulation module (1) is used to produce the led light source modulation signal, and each led light source is switched according to modulation signal, make each led light source in the led light source array luminous successively with extinguish;

Optical fiber Fabry-Perot sensor array (7) is used to experience ambient pressure and changes, and pressure is converted into Fa-Po cavity information, and the corresponding different Fa-Po cavities of different pressures chamber is long;

Fibre coupler arrays (5): be used for the light that the led light source array sends is incorporated into the optical fiber Fabry-Perot sensor array, and the light that the optical fiber Fabry-Perot sensor array returns is incorporated in the demodulation light path module;

The demodulation light path module is used to receive the light signal that fibre coupler arrays returns, and the low coherence interference signal is changed into electric signal, and wherein fiber array (8) signal parallel that fibre coupler arrays is returned imports in the demodulation light path;

Signal processing unit; Based on embedded system or computing machine, be used for extracting the chamber long from electric signal, and corresponding one-tenth pressure measurements;

A led light source (2), an optical fiber Fabry-Perot sensor (6) and a fiber coupler (4) constitute one road pressure sensing passage; In advance each road pressure sensing passage being carried out transducing signal demarcates; This transducing signal calibration value promptly this passage optical fiber Fabry-Perot sensor chamber long with demodulation light path in the corresponding relation of line array CCD (10) position of interference fringe of gathering, as the demodulation foundation of signal processing unit (11).

2. array multichannel optical fiber method amber pressure sensor device as claimed in claim 1; It is characterized in that; The fiber-optic output (12) of said fiber array (8) is arranged by certain dot matrix shape, comprises a single word lattice arrangement architecture, double dot matrix arrangement architecture and arranges dot matrix or circular dot matrix arrangement architecture more.

3. array multichannel optical fiber method amber pressure sensor device as claimed in claim 1 is characterized in that, said led light source modulation module (1) output modulating frequency is at the modulation signal of 10Hz to 40kHz.

4. array multichannel optical fiber method amber pressure sensor device as claimed in claim 1 is characterized in that the quantity of said passage is designed to 3 to 64 paths.

5. array multichannel optical fiber method amber pressure sensor device as claimed in claim 1 is characterized in that, said fiber coupler adopts 1 * 2 multi-module optical fiber coupler, and the optical fiber specification comprises 50/125 μ m, 62.5/125 μ m, 80/125 μ m or 100/125 μ m.

6. utilize the pressure measurement method of the described array multichannel optical fiber of claim 1 method amber pressure sensor device, it is characterized in that this method may further comprise the steps;

Step 1, a led light source (2), an optical fiber Fabry-Perot sensor (6) and a fiber coupler (4) are constituted one road pressure sensing passage; In advance each road pressure sensing passage being carried out transducing signal demarcates; This transducing signal calibration value by this passage optical fiber Fabry-Perot sensor chamber long with demodulation light path in line array CCD (10) the corresponding relation of collection position of interference fringe, as the demodulation foundation of signal processing unit (11).

Step 2, the acquisition process of carrying out, promptly led light source modulation module (1) produces the led light source modulation signal, makes the led light source (2) in a certain moment led light source array (3) luminous, the unglazed output of other led light source (2); The light of this paths of LEDs light source (2) output arrives optical fiber Fabry-Perot sensor (6) through coupled fiber coupler (4), makes pressure signal be modulated to light signal; Light signal imports to the corresponding optical fiber in the fiber array (8) through fiber coupler (6) once more, and gets into the demodulation light path module through the fiber-optic output (12) of fiber array (8);

Step 3, light signal form space low coherence interference striped through the wedge (9) of demodulation light path module, and are received by line array CCD (10), and the signal output and the led light source modulation signal of line array CCD keep synchronously;

Step 4, signal processing unit (11) are handled the interferometric fringe signal of line array CCD (10) output, therefrom extract the Fa-Po cavity signal, and go out pressure measurements according to the nominal data correspondence;

Step 5, repetition above-mentioned steps two are to step 4, up to the pressure that demodulates all passages.

Images