TW200530567A - Lateral pressure sensor based on Fiber Bragg Grating(FBG) - Google Patents

Abstract

The present invention relates to a lateral pressure sensor based on fiber bragg grating, comprising a Fiber Bragg Grating (FBG) whose length is determined in accordance with user's needs and a lateral pressure sensor. The lateral pressure sensor has a hollow cylinder case wherein at least one aperture is disposed at the two sides thereof; at the aperture of the case, flexible polymer is filled and a hard sheet is disposed at the terminal of the polymer so as to encapsulate the fiber grating in the polymer and couple one of the terminals with the hard sheet while another extending through the case. By the configuration of the present invention, the lateral pressure sensor based on Fiber Bragg Grating can be constructed, which can be used as a pressure sensor, a water level recorder, or a underwater depth gauge.

Description

200530567 200530567 V. Description of the invention (2) Most of them seem very heavy, and they increase the manufacturing cost, and reduce the workplace in industrial production and large-scale platforms (such as the monitoring system required, pressure sensors are in the number Very high ratio; in addition, it can also be used to achieve measurements such as gas, liquid, etc. Therefore, the implementation of fiber grating compression is a step towards the all-optical path monitoring system. Practical chemists are engaged in fiber grating pressure for the backbone for a few years, Fiber Bragg Grating Pressure Sensor 1.98x 10 —6 / Mpa reaches _3 · 41x 1 (Except. Therefore, the current practical application pressure: uniform) Fiber Bragg Grating (Fiber) is connected to or indirectly receives the light generated by external pressure The amount of wavelength displacement is further used to eliminate the 5 bare fiber grating pressure sensor system (its sensing sensitivity is only -2 · 0 2x]. The sensor can also be subjected to the special constriction strain amplification effect by the fiber grating in order to At the phase center wavelength, the vertical displacement is 3.41x 10 ^ 3 MPa-1. However, in the case of 'except the pressure sense in the monitoring system', only the conventional fiber grating pressure sense is used. 'Its sensing sensitivity has not been effectively applied, which is why it is so big. So, it is not only a space that can be used. Boats, airplanes 箄 1: The required device two ;: The full transport of the detector or the liquid level The research and application of the measuring instrument is of great importance. For the current research of many measuring instruments, the sensitivity in the short spoon has been repeatedly visited by 1%! Ran has increased, and it has been improved by force. The fold sensing rigid device is based on uniform Grating (FBG) pressure change caused by direct compression strain, which is connected to the pressure contact of the media outside g. 1). In addition, after the pressure edge material is packaged, 俾 produces Under the same pressure to obtain greater middle sensitivity only as described above-industrial production or safety requirements, the sensitivity of the measurement has a continuous improvement of the way to measure the level of liquid level; and the use of special materials is known Φ

surface

Page 6 200530567 V. Description of the invention (3) | The pressure sensor of the material package belongs to the technical application of the fiber grating axis. Whether it is located in the center of the structure during the packaging process and whether it is measured is related to the quality of the measurement, so it increases. In order to understand the difficulty and accuracy of packaging, the inventors of this case based on research and innovation and the future == high demand for industrial and industrial use, that is, the fiber grating industry and military sensor composition technology for deeper innovation and improvement, The pressure-sensing device for pressure-sensing sensitivity, which breaks the habit of knowing = two kinds of bottles that can increase I sensitivity, and can be used as a liquid level measuring device. I force sensor [Before / invention of k fiber fiber Y pressure pressure | fiber grating relationship, its I reached the measurement and this | mechanism, and to be stronger for the composition | fiber grating with short grating to adjust Compression bonding simply knows bare light (the purpose of the fiber / machine that works for short center wavelengths for the mouth. Invented the side pressure is known when pressure is reflected when the pressure is reflected), but also the optical wavelength fiber grating of the force sensor Pressure sensors, whose Bragg Grating (FBG) wavelength direction shifts, in other words, shifts, are different from pressure changes, that is, Bragg fiber grating Bragg fiber grating pressure sensors. The present invention relates to short-length fiber gratings. (Short device; for high reflection intensity problems, a longer length can be used to form a pressure sensor; and this size method, if you change its sensing demodulation mechanism, you can directly make the center of the feature is negative. The optical fiber for the optical fiber needs of the pressure sensing device is invented. The measurable spirit can work with the Bragg wavelength and the linear compression of the Brahm light rate. The other grating (as required length, acuity, Pei

200530567 V. Description of the invention (4) The main embodiment of the side-pressure Bragg fiber grating pressure sensing device according to the present invention includes a uniform length (unif0rm) or other types of Bragg fiber gratings , FBG), and a side pressure type pressure sensor; wherein the side pressure type pressure sensor has a hollow cylindrical shell, and at least one opening on the two sides of the selected shell is connected to the outside, And the interior of the housing at the opening position is filled with a polymer with elasticity, and a hard plate is selected at the end of the polymer shaft to thereby make the uniform fiber grating be covered in the polymer, and one end of the fiber grating It is combined with a hard plate, and the other end extends out of the casing, thereby constituting a side-pressure Bragg fiber grating pressure sensing device according to the present invention, and can be applied as a pressure sensor, a water level gauge or an underwater depth gauge. As described above, the Bragg fiber grating of the present invention selects a practical application length according to demand. The implementation includes the use of a short fiber grating to form a side pressure type pressure sensing device, and the use of a long fiber grating to form a side pressure type pressure sensing device. The two forms. [Embodiment] The following describes the structural features and other functions and purposes of the present invention in detail according to the embodiments of the accompanying drawings as follows: β As shown in the drawings, the present invention is designed as a "side pressure Bragg fiber Bragg grating pressure sensing device", It is mainly composed of a Bragg fiber grating and a pressure pressure sensor 2 on one side, of which, "Brag fiber grating 1" can be a uniform type (uni f ... about fiber grating (Fiber Bragg Grating, FBG) or other types of fiber gratings, and the length of the fiber grating is determined according to the strength of the reflected light.

Page 8 200530567 V. Description of the invention (5) Short fiber gratings can be used when strong reflected light is not needed, or long fiber gratings can be used for high reflection intensity requirements), side pressure pressure sensors 2 ' It has a hollow cylindrical shell 21, and at least one opening 22 connected to the outside is provided on the selected side of the shell 22, and the inside of the shell 21 at the opening 22 is filled with a full state and A polymer 2 3 'having a proper elasticity allows the polymer 2 3 to withstand external pressure through the opening, and a rigid plate 2 4 is provided at the axial end 2 3 1 of the polymer 2; A Bragg fiber grating 1 is formed in a polymer 2 3 coated in a side pressure type pressure sensor 2 in its casing 2 1, and one end of the fiber grating 1 is fixed to the inner end of the hard plate 24, and the optical fiber is The other end of the grating 1 extends out of the housing 21, if this can constitute the strain generated by the radial pressure on the polymer 23, the chirp drives the light, and the center wavelength of the grating 1 is shifted to further achieve the side pressure type of the pressure measurement effect. Bragg fiber grating pressure sensing device. In the above example, the uniform or other types of Bragg fiber gratings are selected according to demand. The implementation method is to use a short fiber grating 1 A to form a side-pressure Bragg fiber. As shown in the first and second figures, the grating pressure sensing device is a hollow cylindrical cylindrical housing 2 1 that can be adopted, and one of the < ^ holes 2 2 (such as As shown in the figure, it can be a round hole). The inside of the housing 2 1 contains a short-traveling grating 1 A and a full state (half-full as shown in the figure). Object 23, cough 2 3 1 at the axial end of the polymer 23, and set up a hard house and a plate 2 4 (which can be a disc), and make the short light-woven woven grid 1 A covered with elasticity In the polymer 2 3, this group requires a strong reaction, > side-type Bragg fiber optic thumb pressure sensor just installed

200530567

V. Description of the invention (6) In addition, the embodiment of the present invention also includes a side-pressure Bragg fiber Bragg grating pressure sensing device composed of Yixian κ 九 κ # Μ 1 R It also adopts a circular hollow column-shaped outer h 'as shown in the second figure Γ fork 21, and an opening hole 2 2 is provided on the two sides of the cymbal (as shown in the figure, it can be a round hole). Μ $ 1 j ^ q 立 β contains a long fiber grating 1 Β and a polymer in a suitable state (such as R ^ Π α | full) as the polymer of the appearance of the long fiber grating 1 B? Q ', a second 3, a hard plate 2 4 (also a round Η' Λ port,. Θ body) is provided at the axial end 2 3 1 with the character 23, and the long fiber grating 1B is completely covered Cover & Flexible

Q Α <inside the compound 23 'and a channel 2 5 is provided at the selected end of the housing 2 1 to accommodate a long fiber optic thumb β, thereby forming a pressure-sensing side-pressure Bragg fiber grating pressure sensor with high reflected light intensity requirements测 装置。 Testing device. ° Using the side pressure Bragg fiber grating pressure sensing device of the present invention to design 'the relationship between the center wavelength and pressure of the short fiber grating side pressure pressure sensor is: the short fiber grating 1 A is lined with polymer 2 3, Let the fiber grating 1 A be located at the center of the polymer 2 3; first consider the situation where the polymer 2 3 is under pressure or stress in the y direction in three-dimensional space (as shown in the fifth figure).

When there is only a force in the y direction and the pressure is P, v and E are the Busson's ratio and the elastic modulus of the polymer, respectively.

εwide-rush yE ε, ρ1Λ, that is, when the pressure ρ in the y direction is generated, it will be divided into X and y, respectively.

Page 10 200530567 V. Description of the invention (7) The z-direction produces ~ heart, ~ strain. Now, if the number of elastic cores is ′ and the cross-sectional area is short, the optical fiber shank 1 A is buried along the z axis and set on the central axis of this polymer 2 3 (as shown in the sixth figure).

), And one end of the short fiber grating 1 A is glued to the center point of a circular rigid plate 2 4 with the same cross-sectional area as that of the polymer 23 and flat against the end face of the polymer 2 3, and the other end is fixed to the polymer 2 3 At the center point of the bottom surface. When the y-direction is subjected to a pressure of P, a stress is generated along the axial direction (Z-direction), and a large force is generated on the end face of the round hard plate 2 of the polymer 23, wherein the round hard plate The area of sheet 24 is A. This force acts on the short fiber grating 1 A and polymer 2 3 at the same time, so it can be expressed as: FR = ^ b6r + ^ fiber = ^ fiber ^ fiber ^ polymtr = εpolymer XX ^ p〇fymer

When the sensor is under pressure, since the polymer 2 3 has the same axial strain as the short fiber grating 1 A (FBG), that is, p ~ εfiber = £ polymer, which means that: -vPxA ^ sz [axEfiUr + {Aa) Epolymer]

therefore:

__- vPA fiber + ~ a) ^ fotywey If the polymer 2 3 is present in the outer shell 21 of 1 (as shown in the seventh figure), except for the X direction ~ it will not happen due to the coating of the outer shell 21 In addition, the strains in the y and z directions are still very small compared to ^, so they can be ignored.

Page 11 200530567

. The relationship between the wavelength and pressure of a side-pressed Bradford fiber with this structure is mainly affected by the stress of the center wavelength of the fiber, which affects the center wavelength of the grating. The pressure of the grating pressure sensor in the grating (z direction) Relevant mathematical formulas are: = medium% is the center wavelength displacement amount, ^ is the central wave before pressure, 'is the fiber strain coefficient, and &amp; is the amount of strain. And this kind of structure = the main working mechanism of the pressure type Bragg fiber grating pressure sensor

= The pressure obtained is converted into axial strain by the aid of the polymer, and then the sensitivity characteristic of the force ti, so the above formula can be rewritten as the relationship between the central wavelength of the fiber and the impact of the dust, which is expressed as: fiber + (-^ a) -^ p〇lywer = finishing ~ as shown below, it can be observed that if the circular rigid plate, the area (A) is larger than the cross-sectional area of the fiber, the larger the axial strain of the grating

=--VP a -----

/ As for the center wavelength and pressure sense of the long fiber grating side pressure pressure sensor, the difference between this type of sensor and the short fiber grating sensor described above is the axial length of the polymer 23 and the fiber grating ( FBG) length is not L = structure sense: the device can solve the problem of high-intensity Bragg customers, and it is necessary to use a longer fiber grating if necessary. (Such as: "iron: up to = force, it will be along the axis &quot; direction) Size: And on the end of the round hard plate 24 of" 23 "will be J ~ ~ force, this Force acts on both the fiber grating and the

200530567 V. Description of the invention (9) The compound is: ^ fiber ^ polymer

Ffiber = 4⑽ XaxEfber ^ polymer = ^ polymer ^ ^ ^ polymer When the sensor is under pressure, the amount of change in the axial length of polymer 23 and fiber grating (FBG) will be the same, but in the case where the original lengths of the two are different Will make the resulting dependent variables different, namely:

and so

(Α-α) ΕρσΙ ^ € τ

= hL Known: Then:

-vP ^ A-[(«xEfiher) + (Λ ~ α) Ερφηβγ] Lfiber ^ pofymtr £ fiber

AL therefore: L fiber λΕ

^ fiber ^ p〇fym € T {A-d) E ¥ 〇lywer The related mathematical expressions affected by the stress of the fiber's center wavelength can be rewritten by the above formula to be affected by the pressure of the fiber's center wavelength, which is expressed as follows: So:

-vPA (A-a) Epi L fiber

Page 13 200530567 V. Description of the invention (10) Taking the length of the long fiber grating 1 B as twice as the axial length of the polymer 2 3 as an example, then: (Bu Qiao) Borrow the implementation form on the use side In the sensitivity experiment of the pressure type short fiber grating pressure sensing mechanism, the results as shown in Figure 9 and Figure 9B can be obtained. 'This figure is a pressure-wavelength relationship diagram of a side pressure short fiber grating pressure sensor.' As shown in the figure, the reflection center wavelength of the short fiber grating 1 A is shifted from the original 1 5 3 9 · 8 nm to 1 5 4 5 · 6 nm. The function of this pressure sensor is increased by 0 · IMpa. 87x10-2Mpa。 Pressure, will increase linearly with an increase of 2. 88nm, in other words, its sensitivity to pressure measurement is 1. 87x10-2Mpa. -In addition, in the sensitivity experiment of the side-pressing type long fiber grating pressure sensing mechanism, the results shown in Figures 10A to 10e (which are the results of the side-pressing type long fiber grating pressure sensor) can be obtained. The relationship between pressure and wavelength ^, where the tenth graph A to tenth graph respectively represent the pressure of the side-pressing long fiber grating, the tester is subjected to a pressure of 0.02Mpa, 0.05Mpa, 0.00lpa, 0.2Mpa, From the tenth figure e, it can be seen that the reflection center wavelength of the long fiber grating b is shifted from the original 1 539.922 nm to -46. 42 9 nm. The function of such a long fiber grating pressure sensor increases by 0 · For 1 M pa pressure, change q π 7 R ni, say U: r ί, and shift upwards linearly by 3. 3 8 76—incremental, and the sensitivity to pressure summer measurement can reach 2.2xl0_2. The sensitivity of the optical grating to pressure sensing is not good. To achieve this, the fiber grating can be implemented as a special cracked structure of the present invention.

Page 14 200530567 V. Description of the invention (11) The packaging of axial tension can indeed achieve a more sensitive pressure sensing effect. In the application of the sensor, the requirements for strong and weak fiber gratings are different and the use of space Limitations have led to two possible side-pressed fiber Bragg grating pressure structure sensors. Due to their different structures, the sensitivity of these two types of sensors is also different. You can choose the appropriate sensor structure according to their needs. When the signal has a strength requirement, the side pressure type long fiber grating pressure sensing mechanism can be used to achieve the pressure sensing purpose. The circular hard plate in the pressure measuring fiber grating pressure sensor has a 2 4 area. Enlargement can effectively increase the sensitivity of pressure sensing. Because of its small size, the side pressure pressure sensing mechanism can also be used in environments where space usage is limited. The above experimental results show that the combination of the side-pressing fiber grating pressure sensor of the present invention and the semi-stable demodulation optical path does have the function of effectively performing pressure measurement, and the high sensitivity of pressure sensing is widely used in addition to In addition to the considerable measurement capability in water level measurement applications, it also has a high potential in the measurement and application of diving depth in water vehicles.

Page 15 200530567 Brief description of the drawings The first diagram is a schematic cross-sectional view of a side-pressure short fiber grating pressure sensor according to the present invention. The second figure is a schematic diagram of the appearance of a side-pressing short fiber grating pressure sensor according to the present invention. The third figure is a schematic sectional view of a side-pressing type long fiber grating pressure sensor according to the present invention. The fourth figure is a schematic diagram of the appearance of a side-pressing long fiber grating pressure sensor according to the present invention. The fifth figure is a schematic diagram of the axial strain generation of the polymer inside the side pressure sensor of the present invention. The sixth figure is a schematic diagram of the axial displacement of the circular flat plate inside the side pressure sensor of the present invention. The seventh diagram is a schematic diagram of the pressure of the short fiber grating side pressure type pressure sensor of the present invention. The eighth diagram is the schematic diagram of the pressure of the long fiber grating side pressure type pressure sensor of the present invention. The ninth diagram A to ninth diagram B are Pressure-wavelength relationship diagram of the side-pressing short-fiber grating pressure sensor of the present invention. The tenth graph A to the tenth graph B are pressure and wavelength diagrams of the side-pressing short fiber grating pressure sensor of the present invention. [Description of main drawing numbers] Bragg fiber grating 1; short fiber grating 1 A;

Page 16 200530567 Brief description of the drawing Long optical fiber grating 1 B Side pressure type pressure sensor 2; Housing 21; Opening hole 22; Polymer 23; End 231 Hard plate 24; Channel 25;

Claims (1)

200530567 6. Scope of patent application 1. A side-pressure Bradden fiber optic side-pressure housing 2 is selected from the opening with appropriate elastic pressure, and the force sensor is combined with the optical fiber light with a radial center wavelength grid 2 For example, if you apply for light pressure sensing with a dedicated pressure sensing length, if you apply for a pressure sensing segment with a longer pressure sensing degree, you can accommodate 4.If you apply for a special Bragg fiber grating, its long pressure set is outside the fixed side branch. In this case, the offset grating pressure range device of the hard plate pressure pair of the outer casing of the cloth, the external range of the fiber grating device is' the optical fiber sensor, and the optical fiber range of the fiber grating pressure sensing device, including : Grating, which is selected according to the strength of the reflected light. The sensing benefit is a hollow cylindrical shell with at least one opening that communicates with the outside. The interior of the shell is filled with a full and material. With a material, the polymer can withstand a hard plate through an opening at the axial end of the foreign compound; a rag fiber grating is formed in a polymer encapsulated in a side pressure type And the fiber grating is coupled to the chip end at one end, and the other end extends out of the housing. With the strain generated by the polymer, the fiber grating can be driven to achieve a side-pressure Brass sensing device for measuring pressure. The side-pressed Bragg fiber grating described in item 1 Bragg fiber gratings can be used in all kinds of short (short fiber thumb), and they are coated in the polymer in the side-compressed shell. The side-pressed Bragg fiber gratings described in item 1 can use all kinds of long thumbs (long fiber gratings) 'coated in the polymer in the side-pressure housing' and a grating is provided in the housing. aisle. Side-pressed Bragg fiber gratings described in item 1 Page 18 200530567 6. Scope of patent application Pressure sensor, the Bragg fiber grating system can be a uniform fiber grating. 5. The side-pressure Bragg fiber grating pressure sensor as described in item 1 of the scope of patent application. The side-pressure pressure sensor can be adjusted in size as needed to change the sensing sensitivity. Page 19