An experimental device and method for fiber-optic pressure sensing

Abstract

A kind of optical fiber pressure sensing experimental device and method, experimental platform is provided with air pressure chamber, three-dimensional adjusting frame, tester, the side nozzle of air pressure chamber is equipped with inflation mechanism, the other side is equipped with pressure sensing device that communicates with air pressure chamber, top is equipped with pressure gauge, pressure sensing device is equipped with diffuse reflector, three-dimensional adjusting frame is equipped on the side experimental platform of air pressure chamber, three-dimensional adjusting frame is equipped with reflective optical fiber sensor probe or micrometer, reflective optical fiber sensor probe includes light emitting optical fiber and light receiving optical fiber, the light emitting optical fiber and light receiving optical fiber of reflective optical fiber sensor probe are connected with the light output port and light receiving port of tester respectively, tester converts optical signal into voltage signal and is shown by display panel;Method is to survey bellows pressure response curve;Measuring optical fiber sensing probe pressure response characteristic;Draw the P-V response characteristic curve of reflective optical fiber sensing probe, analyze reflective optical fiber sensing probe pressure response characteristic.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of teaching experiment instruments, and particularly relates to a kind of optical fiber pressure sensing experiment device and experiment method. BACKGROUND

[0002] Optical fiber sensing is a kind of brand-new sensing technology, and its characteristics are that the light beam emitted by a light source is sent into an optical fiber sensing device, under the action of different physical parameters to be measured in the outside world, the intensity, wavelength, frequency, phase, polarization state and other parameters of the light change, becoming the optical signal modulated by the physical parameters to be measured, and the measured parameters are obtained after the optical signal is converted and demodulated. Due to the excellent physical, chemical, mechanical and transmission performance of the optical fiber, the optical fiber sensor has the advantages of small size, light weight, anti-electromagnetic interference, corrosion resistance, high sensitivity, wide measurement bandwidth, remote and distributed detection, etc., and has been widely studied and applied.

[0003] Optical fiber pressure sensing is one of the main applications of optical fiber sensing technology. Compared with traditional resistance type, capacitance type, piezoelectric type and Hall type pressure sensors, the optical fiber pressure sensor has the characteristics of small size, good electrical insulation performance, and can be used in flammable, explosive and other harsh environments, etc., and has become a research hotspot in optical fiber sensing technology. Correspondingly, the knowledge about optical fiber pressure sensors has become one of the important teaching contents of the optical information science and engineering, measurement and control technology, physics, optical engineering and other majors in colleges and universities. However, the currently commercialized optical fiber grating pressure sensor and optical fiber Fabry-Perot pressure sensor are basically high-integration sealed structures, and students cannot see the internal structure of the optical fiber pressure sensor, which brings difficulties to the intuitive understanding and mastering of the working principle of the optical fiber pressure sensor. Therefore, it is necessary to establish a transparent and open optical fiber pressure sensor experiment system to help students master the basic principles and use methods of the optical fiber pressure sensor and improve their experimental operation ability. However, there are few such optical fiber pressure sensing experiment devices that can meet the experimental requirements of students at present. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an optical fiber pressure sensing experiment device with simple structure, convenient operation, intuitive and clear experimental effect, and improved experimental operation ability of students.

[0005] The technical scheme adopted to solve the above technical problems is: a kind of optical fiber pressure sensing experimental device, experimental platform is provided with air pressure chamber, three-dimensional adjusting frame, tester, air pressure chamber one side gas nozzle is provided with inflation mechanism, the other side is provided with the pressure sensor device that is communicated with air pressure chamber, top is provided with pressure gauge, pressure sensor device is provided with diffuse reflector, three-dimensional adjusting frame is provided on the experimental platform of air pressure chamber side, three-dimensional adjusting frame is installed with reflective optical fiber sensor probe or micrometer, reflective optical fiber sensor probe is opposite with diffuse reflector and the center line of two coincides, reflective optical fiber sensor probe includes light emitting optical fiber and light receiving optical fiber, light emitting optical fiber and light receiving optical fiber of reflective optical fiber sensor probe are connected with the light output port and light receiving port of tester respectively, tester converts the received optical signal into voltage signal and displays through display panel.

[0006] As a preferred technical scheme, the pressure sensor device is a bellows, one end of the bellows is communicated with the air chamber, the other end is sealed by a sealing cap, the sealing cap is provided with a diffuse reflector, and the center line of the diffuse reflector coincides with the axis of the bellows.

[0007] As a preferred technical scheme, the inflation mechanism is a manual inflation ball, and the gas output end of the manual inflation ball is connected with the gas nozzle of the air pressure chamber through a nut.

[0008] As a preferred technical scheme, the light emitting optical fiber is located at the center of the reflective optical fiber sensor probe, is a multimode optical fiber, and has a fiber core diameter of 1 mm; the light receiving optical fibers are uniformly distributed on a circumference with the light emitting optical fiber as the center and a radius of 0.75 mm, are multimode optical fibers, and have a number of 16, a fiber core diameter of Φ0.265 mm.

[0009] The application also provides an experimental method of the optical fiber pressure sensing experimental device, characterized by comprising the following steps:

[0010] 1) measuring and mapping the pressure response curve of the bellows, and analyzing the pressure response characteristics of the bellows

[0011] S1. install the micrometer on the three-dimensional adjusting frame, adjust the three-dimensional adjusting frame, so that the contact of the micrometer just contacts the diffuse reflector on the pressure sensor device, read the indication value of the micrometer at this time, and take the value as the reference value for measuring the elongation of the bellows;

[0012] S2. The inflation mechanism slowly inflates the air pressure chamber, and the change of the reading of the air pressure gauge is observed, so that the air pressure P in the air pressure chamber is sequentially increased from small to large to 20mmHg, 40mmHg, 60mmHg, 80mmHg, 100mmHg, 120mmHg, 140mmHg, 160mmHg, 180mmHg, 200mmHg, 220mmHg, 240mmHg, 260mmHg, 280mmHg, 300mmHg, and the elongation L of the bellows corresponding to each air pressure value P is synchronously read on the micrometer;

[0013] S3. The bellows pressure response curve is drawn with the air pressure value P as the horizontal coordinate and the elongation L corresponding to the bellows as the vertical coordinate.

[0014] 2) Measure the air pressure response characteristics of the optical fiber sensing probe

[0015] S1. The micrometer is removed from the three-dimensional adjustment frame, the reflective optical fiber sensing probe is replaced, the tester is turned on, the tester outputs light, the three-dimensional adjustment frame is adjusted, the distance between the reflective optical fiber sensing probe and the diffuse reflector on the bellows is changed, and the change of the voltage value on the display panel is observed at the same time. When the voltage value is maximum, the three-dimensional adjustment frame is fixed, and the voltage value is recorded;

[0016] S2. The inflation mechanism is adjusted, so that the air pressure P in the air pressure chamber is gradually reduced according to 280mmHg, 260mmHg, 240mmHg, 220mmHg, 200mmHg, 180mmHg, 160mmHg, 140mmHg, 120mmHg, 100mmHg, 80mmHg, 60mmHg, 40mmHg, 20mmHg, and the voltage value V corresponding to each air pressure value on the tester is synchronously read.

[0017] 3) Draw the P-V response characteristic curve of the reflective optical fiber sensing probe, and analyze the air pressure response characteristics of the reflective optical fiber sensing probe.

[0018] The beneficial effects of the present application are as follows:

[0019] The present application uses the reflective optical fiber sensing probe to collect the light signal related to the size of the air pressure in the air pressure chamber, and directly displays the size of the air pressure in the air pressure chamber through the voltmeter. It has the characteristics of simple structure, permeability, clear principle, low cost, easy processing and manufacturing, etc. It can well meet the experimental teaching needs of the photoelectric information science and engineering, measurement and control technology, physics, optical engineering and other majors in colleges and universities. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic view of the optical fiber pressure sensing experimental device of the present application installing the reflective optical fiber sensor probe 7.

[0021] Figure 2 is the structural schematic diagram of the installation of the micrometer of the optical fiber pressure sensing experimental device of the present application.

[0022] Figure 3 is the installation schematic diagram of the light emitting optical fiber and the light receiving optical fiber of the reflective optical fiber sensor probe of the present application. DETAILED DESCRIPTION

[0023] The present application will be further described in detail below in combination with the drawings and examples, but the present application is not limited to the following embodiments.

[0024] In Figure 1 , 2 , the optical fiber pressure sensing experimental device of the present embodiment in Figs. 1, 2 and 3 is composed of an experimental platform 1, a hand-operated inflation ball 2, a gas pressure chamber 3, a pressure gauge 4, a bellows 5, a diffuse reflector 6, a reflective optical fiber sensor probe 7, a three-dimensional adjusting frame 8, a tester 9 and a micrometer 10.

[0025] The experimental platform 1 is fixedly installed with the gas pressure chamber 3, the three-dimensional adjusting frame 8 and the tester 9. The left side gas nozzle of the gas pressure chamber 3 is connected with the hand-operated inflation ball 2 through a nut, the right side is installed with the bellows 5 which is in communication with the gas pressure chamber 3, and the top is installed with the pressure gauge 4. The bellows 5 is used as a pressure sensing device. The bellows 5 has 6 corrugations, a length of 6.7 mm, a diameter of 26.8 mm, a wall thickness of 0.22 mm and is made of tin bronze. The other end of the bellows 5 is sealed through a sealing cover. The diffuse reflector 6 is fixedly installed on the sealing cover. The center line of the diffuse reflector 6 coincides with the axis of the bellows 5. The three-dimensional adjusting frame 8 is fixedly installed on the experimental platform 1 at the right side of the gas pressure chamber 3. The reflective optical fiber sensor probe 7 or the micrometer 10 is installed on the three-dimensional adjusting frame 8. The micrometer 10 is used to measure the pressure response characteristics of the bellows. The reflective optical fiber sensor probe 7 is opposite to the diffuse reflector 6 and the center lines of the two coincide. The reflective optical fiber sensor probe 7 includes a light emitting optical fiber 7-1 and a light receiving optical fiber 7-2. The light emitting optical fiber 7-1 is located at the center of the reflective optical fiber sensor probe 7 and is a multi-mode optical fiber with a fiber core diameter of 1 mm. The light receiving optical fiber 7-2 is uniformly distributed on a circumference with the light emitting optical fiber 7-1 as the center and a radius of 0.75 mm. The light receiving optical fiber 7-2 is a multi-mode optical fiber with a fiber core diameter of Φ0.265 mm and a number of 16. The light emitting optical fiber 7-1 and the light receiving optical fiber 7-2 of the reflective optical fiber sensor probe 7 are connected with the light output port and the light receiving port of the tester 9 respectively. A white light source is installed in the tester 9 and is connected with the light output port. A photoelectric conversion device and a display panel are installed in the tester 9. The input end of the photoelectric conversion device is connected with the light receiving port, and the output end is connected with the display panel. The tester 9 converts the received light signal into a voltage signal through the photoelectric conversion device and displays the voltage signal through the display panel.

[0026] The light emitted by the white light source in the tester 9 is emitted to the light emitting fiber 7-1 of the reflective optical fiber sensor probe 7 through the light output port, the light emitted by the light emitting fiber 7-1 is irradiated to the diffuse reflector 6, the diffuse reflector 6 reflects part of the light to the light receiving fiber 7-2 of the reflective optical fiber sensor probe 7, the light receiving fiber 7-2 transmits the light to the tester 9, and the light is converted into a voltage signal through the photoelectric conversion device inside the tester 9 and then displayed through the display panel. The strength of the electric signal is proportional to the intensity of the light received by the light receiving fiber 7-2, and the intensity of the light received by the light receiving fiber 7-2 is related to the distance between the reflective optical fiber sensor probe and the diffuse reflector 6. In the case that the relative position of the optical fiber sensor probe and the air pressure chamber 3 is determined, the distance between the optical fiber sensor probe and the diffuse reflector 6 is related to the size of the air pressure in the air pressure chamber 3. The greater the air pressure in the air pressure chamber 3, the greater the elongation of the bellows 5, and the smaller the distance between the optical fiber sensor probe and the diffuse reflector 6. Correspondingly, the air pressure in the air pressure chamber 3 decreases, the elongation of the bellows 5 decreases accordingly, and the distance between the optical fiber sensor probe and the diffuse reflector 6 increases.

[0027] The experimental method of the optical fiber pressure sensing experimental device includes the following steps:

[0028] 1) Measuring and mapping the pressure response curve of the bellows 5

[0029] S1. Install the micrometer 10 on the three-dimensional adjusting frame 8, adjust the three-dimensional adjusting frame 8 so that the contact of the micrometer 10 is in contact with the diffuse reflector 6 on the pressure sensing device, read the indication value of the micrometer 10 at this time, and take this value as the reference value for measuring the elongation of the bellows 5;

[0030] S2. Slowly inflate the air pressure chamber 3 by manually inflating the ball 2, observe the reading change of the air pressure gauge, and sequentially increase the air pressure P in the air pressure chamber 3 from small to large to 20mmHg, 40mmHg, 60mmHg, 80mmHg, 100mmHg, 120mmHg, 140mmHg, 160mmHg, 180mmHg, 200mmHg, 220mmHg, 240mmHg, 260mmHg, 280mmHg, 300mmHg, and simultaneously read the elongation L of the bellows 5 corresponding to each air pressure value P on the micrometer 10;

[0031] S3. Draw the pressure response curve of the bellows 5 by taking the air pressure value P as the horizontal coordinate and the elongation L of the bellows 5 as the vertical coordinate, and analyze the pressure response characteristics of the bellows 5;

[0032] 2) Measuring the pressure response characteristics of the optical fiber sensor probe

[0033] S1. Remove the dial gauge 10 from the three-dimensional adjustment frame 8, replace it with a reflective optical fiber sensing probe, turn on the tester 9, output light, adjust the three-dimensional adjustment frame 8, change the distance between the reflective optical fiber sensing probe and the diffuse mirror 6 on the corrugated pipe 5, and observe the change of the voltage value on the display panel at the same time. When the voltage value is maximum, fix the three-dimensional adjustment frame 8 and record the voltage value;

[0034] S2. Adjust the nut between the manual air inflation ball 2 and the air pressure chamber 3, so that the air pressure P in the air pressure chamber 3 decreases according to 280mmHg, 260mmHg, 240mmHg, 220mmHg, 200mmHg, 180mmHg, 160mmHg, 140mmHg, 120mmHg, 100mmHg, 80mmHg, 60mmHg, 40mmHg, 20mmHg, and synchronously read the voltage value V on the tester 9 corresponding to each air pressure value;

[0035] 3) Draw the P-V response characteristic curve of the reflective optical fiber sensing probe, and analyze the air pressure response characteristics of the reflective optical fiber sensing probe.

Claims

1. An experimental device for fiber optic pressure sensing, characterized in that: The experimental platform (1) is equipped with a pressure chamber (3), a three-dimensional adjustment frame (8), and a tester (9). The pressure chamber (3) has an inflation mechanism on one side of the air nozzle, a pressure sensor connected to the pressure chamber (3) on the other side, a pressure gauge (4) on the top, a diffuse reflector (6) on the pressure sensor, a three-dimensional adjustment frame (8) on one side of the pressure chamber (3), a reflective fiber optic sensor probe (7) or a dial gauge (10) on the three-dimensional adjustment frame (8), the reflective fiber optic sensor probe (7) and the diffuse reflector (6) are opposite each other and their center lines coincide. The reflective fiber optic sensor probe (7) includes an optical emitting fiber (7-1) and an optical receiving fiber (7-2). The optical emitting fiber (7-1) and the optical receiving fiber (7-2) of the reflective fiber optic sensor probe (7) are connected to the optical output port and the optical receiving port of the tester (9) respectively. The tester (9) converts the received optical signal into a voltage signal and displays it through the display panel. The pressure sensor is a bellows, with one end connected to the pressure chamber and the other end sealed by a sealing cap. A diffuse reflector is installed on the sealing cap, and the center line of the diffuse reflector coincides with the axis of the bellows.

2. The fiber optic pressure sensing experimental device according to claim 1, characterized in that: The inflation mechanism is a manual inflation ball, and the gas output end of the manual inflation ball is connected to the air nozzle of the pressure chamber by a nut.

3. The fiber optic pressure sensing experimental device according to claim 1, characterized in that: The optical transmitting fiber (7-1) is located at the center of the reflective optical fiber sensor probe (7), and is a multimode fiber with a core diameter of 1 mm. The optical receiving fiber (7-2) is evenly distributed on a circle with a radius of 0.75 mm centered on the optical transmitting fiber (7-1). The optical receiving fiber (7-2) is a multimode fiber, with 16 fibers and a core diameter of 0.265 mm.

4. The experimental method of the fiber optic pressure sensing experimental device according to any one of claims 1-3, characterized in that, Includes the following steps: 1) Plot the pressure response curve of the bellows and analyze its pressure response characteristics. S1. Install a dial indicator on the three-dimensional adjustment frame, adjust the three-dimensional adjustment frame so that the contact of the dial indicator is just in contact with the diffuse reflector on the pressure sensor, and read the reading of the dial indicator at this time. Use this value as the reference value for measuring the elongation of the bellows. S2. The inflation mechanism slowly inflates the pressure chamber, and the changes in the pressure gauge reading are observed. The pressure P in the pressure chamber is increased sequentially from small to large to 20 mmHg, 40 mmHg, 60 mmHg, 80 mmHg, 100 mmHg, 120 mmHg, 140 mmHg, 160 mmHg, 180 mmHg, 200 mmHg, 220 mmHg, 240 mmHg, 260 mmHg, 280 mmHg, and 300 mmHg. At the same time, the elongation L of the bellows corresponding to each pressure value P is read on the dial gauge. S3. Plot the pressure response curve of the bellows with the air pressure value P as the abscissa and the elongation L corresponding to the bellows as the ordinate; 2) Measurement of the air pressure response characteristics of the fiber optic sensing probe S1. Remove the dial indicator from the three-dimensional adjustment frame, replace it with a reflective fiber optic sensor probe, turn on the tester, and the tester outputs light. Adjust the three-dimensional adjustment frame to change the distance between the reflective fiber optic sensor probe and the diffuse reflector on the corrugated pipe. At the same time, observe the change in the voltage value on the display panel. When the voltage value is at its maximum, fix the three-dimensional adjustment frame and record this voltage value. S2. Adjust the inflation mechanism to gradually decrease the air pressure P in the air pressure chamber according to the following levels: 280 mmHg, 260 mmHg, 240 mmHg, 220 mmHg, 200 mmHg, 180 mmHg, 160 mmHg, 140 mmHg, 120 mmHg, 100 mmHg, 80 mmHg, 60 mmHg, 40 mmHg, and 20 mmHg. Simultaneously read the voltage value V on the tester corresponding to each air pressure value. 3) Plot the PV response characteristic curve of the reflective fiber optic sensor probe and analyze the air pressure response characteristics of the reflective fiber optic sensor probe.

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