Sensor packaging method and optical fiber high-temperature strain sensor

Abstract

The invention relates to the technical field of optical fiber sensors, and provides a sensor packaging method and an optical fiber high-temperature strain sensor.The sensor packaging method is implemented aiming at a to-be-packaged structure, the to-be-packaged structure comprises a substrate and an optical fiber, a hollow-out area is formed in the substrate, the optical fiber stretches across the hollow-out area above the hollow-out area, and the hollow-out area is arranged between the substrate and the optical fiber. A tensioning implementation part is arranged on the section, stretching across the hollow area, of the optical fiber; the packaging method of the sensor comprises the following steps of: pre-loosening an optical fiber, jacking a tensioning implementation part of the optical fiber by using a pre-tightening adjusting mechanism, and stopping jacking operation after the distance between the tensioning implementation part and a substrate reaches a target pre-loosening adjusting distance; and optical fiber connection: respectively connecting a first connection point on one side of the tensioning implementation part and a second connection point on the other side of the tensioning implementation part of the optical fiber to the upper surface of the substrate, and the packaging method of the sensor can solve the technical problem that the optical fiber in the fiber grating sensor in the prior art is easy to break at high temperature.

Description

Technical Field

[0001] The present application relates to the technical field of optical fiber sensors, and more specifically, to a sensor packaging method and an optical fiber high-temperature strain sensor. Background Art

[0002] With the rapid development of various types of high-speed aircraft, the aerodynamic thermal environment in service is becoming increasingly harsh. The heat protection problem caused by the harsh aerodynamic thermal environment has become one of the problems restricting the development of high-speed aircraft. The response characteristics of heat-resistant materials in high-temperature environments are the basis of aircraft thermal protection design. Accurately measuring the thermal performance of heat-resistant materials in high-temperature environments has important guiding significance for the design of thermal structures. Fiber optic sensors are a new generation of sensors with unique advantages such as small size, light weight, high temperature resistance, corrosion resistance, anti-electromagnetic interference, distributed measurement points, easy networking, and simultaneous measurement of multiple parameters. Therefore, high-temperature resistant fiber optic materials are very suitable for measuring high-temperature strain environments.

[0003] Fiber Bragg grating sensors can be used for sensing and measuring physical quantities such as stress, strain or temperature, and have high sensitivity and measurement range. By writing fiber Bragg gratings with different grating pitches at several locations on the optical fiber, the corresponding physical quantities and their changes at several locations can be measured simultaneously, thus realizing quasi-distributed optical fiber sensing. In short, the application of fiber Bragg grating sensors is a burgeoning field with very broad development prospects. At present, the optical fiber sensors in the prior art have the disadvantages of being prone to plastic deformation, yielding, and even breaking at high temperatures. They cannot measure high-temperature strain at high temperatures and are usually only suitable for strain measurement at room temperature. In addition, the thermal expansion coefficient of metals is generally much larger than that of optical fibers. At high temperatures, the optical fiber will be stretched or even broken due to the difference in thermal expansion coefficients between the two. Summary of the invention

[0004] In view of this, the present application provides a sensor packaging method and an optical fiber high-temperature strain sensor to solve the technical problem that the optical fiber in the optical fiber grating sensor in the prior art is easy to break at high temperature.

[0005] The present application provides a packaging method for a sensor, wherein the packaging method for the sensor is implemented for a structure to be packaged, wherein the structure to be packaged includes a substrate and an optical fiber placed on the upper surface of the substrate, wherein a hollow area penetrating the substrate along the thickness direction of the substrate is formed on the substrate, the optical fiber crosses the hollow area above the hollow area, and a tensioning implementation portion is provided on the section of the optical fiber crossing the hollow area;

[0006] The packaging method of the sensor comprises the following steps:

[0007] Pre-relaxing the optical fiber, using a pre-tightening adjustment mechanism to pass through the hollow area and allowing the pre-tightening adjustment mechanism to support the tensioning implementation part of the optical fiber in a direction away from the substrate, and stopping the supporting operation after the distance between the tensioning implementation part and the substrate reaches the target pre-relaxation adjustment distance;

[0008] Optical fiber connection, after the pre-tensioning adjustment mechanism stops the supporting operation, the first connection point of the optical fiber located on one side of the tensioning implementation part and the second connection point on the other side are respectively connected to the upper surface of the substrate, so that the structure to be packaged forms a packaged sensor.

[0009] Furthermore, the pre-relaxation method includes: determining the target pre-relaxation adjustment distance based on the magnitude of the strain applied to the optical fiber after the temperature is raised from the initial temperature to the target temperature, so that the optical fiber in the packaged sensor is stretched to a taut state by the substrate after the temperature is raised from the initial temperature to the target temperature.

[0010] Furthermore, the pre-tensioning adjustment mechanism can telescopically move along a direction passing through the hollow area to change the distance between the tensioning implementation position of the optical fiber and the substrate.

[0011] Furthermore, the pre-tensioning adjustment mechanism includes a telescopic driving mechanism and a supporting member connected to the telescopic driving mechanism, wherein the supporting member passes through the hollow area and supports the tensioning implementation position of the optical fiber in a direction away from the substrate.

[0012] Furthermore, the telescopic driving mechanism is a manual lifting platform or an electric lifting platform.

[0013] Furthermore, the packaging method also includes: before performing the optical fiber pre-relaxation step, respectively fixing a first pad and a second pad at the lower ends of the substrate on both sides of the hollow area, placing the first pad and the second pad on a workbench, placing the pre-tensioning adjustment mechanism on the workbench and making the pre-tensioning adjustment mechanism located below the substrate and between the first pad and the second pad.

[0014] Furthermore, the packaging method further comprises: in the optical fiber connection step, the first connection point and the second connection point are respectively glued to the upper surface of the substrate.

[0015] In addition, the present invention also provides an optical fiber high temperature strain sensor, wherein the optical fiber high temperature strain sensor is obtained by the above sensor packaging method, and the optical fiber high temperature strain sensor is a sensor formed after the structure to be packaged is packaged.

[0016] Furthermore, the substrate forms an elastic ring structure around the hollow area, the elastic ring structure is arranged around the hollow area, and the elastic ring structure protrudes from both sides of the substrate along the width direction of the substrate and / or protrudes from both sides of the substrate along the thickness direction of the substrate.

[0017] Furthermore, a first stretching position and a second stretching position arranged at intervals are provided on the substrate, and the first stretching position and the second stretching position are both used to connect to the object to be measured, the first connection point of the optical fiber is connected to the first optical fiber connection position on the substrate, and the second connection point of the optical fiber is connected to the second optical fiber connection position on the substrate, and the packaging method of the sensor includes an optional small strain measurement installation mode and a large strain measurement installation mode. When the packaging method of the sensor is selected as the small strain measurement installation mode, the first optical fiber connection position and the second optical fiber connection position are located between the first stretching position and the second stretching position; when the packaging method of the sensor is selected as the large strain measurement installation mode, the first stretching position and the second stretching position are located between the first stretching position and the second optical fiber connection position, and the substrate has substrate extension parts on both sides of the first stretching position and the second stretching position along the arrangement direction of the first stretching position and the second stretching position, and the first optical fiber connection position and the second optical fiber connection position are respectively located on the corresponding substrate extension parts.

[0018] Compared with the prior art, in the packaging method of the sensor, since the optical fiber pre-relaxation step is performed for the structure to be packaged, that is, a pre-tightening adjustment mechanism is used to pass through the hollow area and the pre-tightening adjustment mechanism is used to support the tensioning implementation part of the optical fiber in a direction away from the substrate, so that the distance between the tensioning implementation part and the substrate reaches the target pre-relaxation adjustment distance and the supporting operation is stopped. In this way, the target pre-relaxation adjustment distance can be set according to actual needs, and the tension relaxation degree of the section of the optical fiber between the first connection point and the second connection point can be flexibly adjusted according to actual needs to avoid excessive strain of the optical fiber at high temperature. As for breakage, specifically, it avoids the phenomenon that the optical fiber is continuously stretched by the metal or even breaks as the temperature rises due to the difference in thermal expansion coefficients between the optical fiber and the metal. The target pre-relaxation adjustment distance can be determined based on the amount of strain the optical fiber is subjected to after the optical fiber is raised from the initial temperature to the target temperature, so that the optical fiber is stretched to a taut state by the substrate at a certain temperature point, thereby realizing high-sensitivity or large-range strain measurement at high temperature. Specifically, the displacement of the pre-tightening adjustment mechanism can be determined to match the required degree of relaxation of the optical fiber through theoretical calculation of the amount of strain the optical fiber is subjected to when the temperature is raised to the target temperature.

[0019] Other advantages of the present application will be described in more detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a three-dimensional schematic diagram of an optical fiber high-temperature strain sensor in a packaging process according to an embodiment of the present application;

[0022] Figure 2 for Figure 1 The enlarged view of point A in the middle;

[0023] Figure 3 It is a schematic plan view of an optical fiber high temperature strain sensor in a small strain measurement installation mode when connected to a body to be measured according to an embodiment of the present application;

[0024] Figure 4 It is a schematic plan view of an optical fiber high temperature strain sensor in a large strain measurement installation mode when connected to a body to be measured according to an embodiment of the present application;

[0025] Figure 5 This is a schematic diagram of the structural design principle of an optical fiber high-temperature strain sensor according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. One or more embodiments of the present application are exemplarily given in the drawings to make the understanding of the technical solution disclosed in the present application more accurate and thorough. However, it should be understood that the present application can be implemented in a variety of different forms and is not limited to the embodiments described below.

[0027] The same or similar numbers in the drawings of the present application correspond to the same or similar parts; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0028] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B.

[0029] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0030] See also Figures 1 to 4 According to one aspect of the present invention, a sensor packaging method is provided, wherein the sensor packaging method is implemented for a structure to be packaged, the structure to be packaged includes a substrate 100 and an optical fiber 200 placed on the upper surface of the substrate 100, a hollow area 101 penetrating the substrate 100 along the thickness direction of the substrate 100 is formed on the substrate 100, the optical fiber 200 crosses the hollow area 101 above the hollow area 101, and a tensioning implementation portion 201 is provided on the section of the optical fiber 200 crossing the hollow area 101, wherein the substrate 100 can be a metal substrate 100 in particular, but the material of the substrate 100 can also be ceramic, SiC or other suitable materials, and is not limited to a certain material;

[0031] The packaging method of the sensor includes the following steps:

[0032] Pre-relaxation of the optical fiber, using the pre-tightening adjustment mechanism 300 to pass through the hollow area 101 and make the pre-tightening adjustment mechanism 300 support the tensioning implementation part 201 of the optical fiber 200 in the direction away from the substrate 100, and stop the supporting operation after the distance between the tensioning implementation part 201 and the substrate 100 reaches the target pre-relaxation adjustment distance;

[0033] Fiber optic connection: after the pre-tensioning adjustment mechanism 300 stops supporting, the first connection point of the optical fiber 200 on one side of the tensioning implementation part 201 and the second connection point on the other side are respectively connected to the upper surface of the substrate 100, so that the structure to be packaged forms a packaged sensor.

[0034] In the packaging method of the sensor, since the optical fiber pre-relaxation step is performed for the structure to be packaged, that is, the pre-tightening adjustment mechanism 300 is used to pass through the hollow area 101 and the pre-tightening adjustment mechanism 300 is used to support the tensioning implementation part 201 of the optical fiber 200 in the direction away from the substrate 100, so that the distance between the tensioning implementation part 201 and the substrate 100 reaches the target pre-relaxation adjustment distance and then the supporting operation is stopped. In this way, the target pre-relaxation adjustment distance can be set according to actual needs, and the tension relaxation degree of the section of the optical fiber 200 between the first connection point and the second connection point can be flexibly adjusted according to actual needs, so as to avoid the optical fiber 200 from being broken due to excessive strain at high temperature. Specifically, This avoids the phenomenon that the optical fiber 200 is continuously stretched or even broken by the metal as the temperature rises due to the difference in thermal expansion coefficients between the optical fiber 200 and the metal. The target pre-relaxation adjustment distance can be determined based on the amount of strain applied to the optical fiber 200 after the optical fiber 200 is raised from the initial temperature to the target temperature, so that the optical fiber 200 is stretched to a taut state by the substrate 100 at a certain temperature point, thereby achieving high-sensitivity or large-range strain measurement at high temperatures. Specifically, the displacement of the pre-tightening adjustment mechanism 300 can be determined to match the required degree of relaxation of the optical fiber 200 by theoretically calculating the amount of strain applied to the optical fiber 200 when the temperature rises to the target temperature.

[0035] As mentioned above, the pre-relaxation method may include the steps of: determining a target pre-relaxation adjustment distance based on the amount of strain applied to the optical fiber 200 after the optical fiber 200 is raised from the initial temperature to the target temperature, so that the optical fiber 200 in the packaged sensor is stretched to a taut state by the substrate 100 after the optical fiber 200 is raised from the initial temperature to the target temperature. Of course, as other embodiments, the target pre-relaxation adjustment distance may also be determined one-to-one according to an empirical data table or a built database.

[0036] According to a specific embodiment of the present application, the pre-tensioning adjustment mechanism 300 can telescopically move along a direction passing through the hollow area 101 to change the distance between the tensioning implementation part 201 of the optical fiber 200 and the substrate 100 .

[0037] More specifically, the preload adjustment mechanism 300 includes a telescopic driving mechanism and a top support member 301 connected to the telescopic driving mechanism. The top support member 301 penetrates the hollow area 101 and supports the tensioning implementation position 201 of the optical fiber 200 in a direction away from the substrate 100. The top support member 301 can specifically be a top support block, a top support rod and other components. The end face of the top support member 301 away from the telescopic driving mechanism supports the tensioning implementation position 201 of the optical fiber 200. In order to prevent the optical fiber 200 from slipping and detaching from the top support member 301, the end face of the support member away from the telescopic driving mechanism can also form a limiting groove, and the optical fiber 200 is accommodated in the limiting groove, or the width of the top support member 301 is much larger than the diameter of the optical fiber 200.

[0038] According to a specific embodiment of the present application, the telescopic drive mechanism is a manual lift or an electric lift, or the preload adjustment mechanism 300 is a micro electric push rod. In this case, the end of the piston rod of the micro electric push rod supports the optical fiber 200. Since the manual lift, the electric lift and the micro electric push rod can all adopt known mechanisms.

[0039] Furthermore, the manual lifting platform may include a base 302, a lifting seat 303 connected to the base 302 through a lifting assembly, and the upper part of the lifting seat 303 is connected to the top support member 301. The lifting assembly may include two sets of arm-type connecting rod mechanisms, the arm-type connecting rod mechanisms include a first connecting rod 304, a second connecting rod 305, a third connecting rod 306 and a fourth connecting rod 307, the upper end of the first connecting rod 304 and the upper end of the fourth connecting rod 307 are hinged to each other and hinged to the lifting seat 303, the lower end of the first connecting rod 304 and the upper end of the second connecting rod 305 are hinged to each other and hinged to the first sliding seat 308, the lower end of the second connecting rod 305 and the lower end of the third connecting rod 306 are hinged to each other and hinged to the base 302, and the upper end of the third connecting rod 306 is hinged to each other. The lower ends of the fourth connecting rod 307 are hinged to each other and hinged to the second sliding seat 309. The manual lifting platform can also include a rotatable adjusting rod 310 threadedly matched with the first sliding seat 308 and the second sliding seat 309. By twisting the rotatable adjusting rod 310, based on a principle similar to a lead screw nut, the first sliding seat 308 and the second sliding seat 309 can be made to approach or move away from each other in the length direction of the rotatable adjusting rod 310, thereby controlling the degree of opening and closing of the inserted arm connecting rod mechanism, so that the lifting seat 303 can be lifted and lowered relative to the base 302.

[0040] According to a specific embodiment of the present application, the packaging method further includes: before performing the optical fiber pre-relaxation step, respectively fixing the first cushion block 1 and the second cushion block 2 at the lower ends of the substrate 100 on both sides of the hollow area 101, placing the first cushion block 1 and the second cushion block 2 on the workbench 3, placing the pre-tightening adjustment mechanism 300 on the workbench 3 and making the pre-tightening adjustment mechanism 300 located below the substrate 100 and between the first cushion block 1 and the second cushion block 2. In the optical fiber connection step, the first connection point and the second connection point are respectively glued to the upper surface of the substrate 100, especially using high-temperature glue 4 for gluing, but other suitable connection methods other than gluing are not excluded.

[0041] According to another aspect of the present invention, there is also provided an optical fiber high temperature strain sensor, wherein the optical fiber high temperature strain sensor is obtained by the packaging method of the above-mentioned sensor, the optical fiber high temperature strain sensor is a sensor formed after the structure to be packaged is packaged, and the optical fiber high temperature strain sensor is a fiber grating strain sensor or a strain sensor based on an optical fiber FP structure, and can also be an optical fiber sensor based on the principle of Faraday-Michelson interferometer, an optical fiber sensor based on the principle of Mach-Zehnder interferometer, etc., wherein the optical fiber FP structure, also called anti-resonant optical fiber (FP optical fiber), is a special optical fiber structure, which is achieved by adjusting the cavity length of the optical fiber core part to be equal to half of the reflection wavelength, thereby eliminating peaks and valleys through reflection and suppressing resonance.

[0042] See also Figure 5 , Δl, L, W, h represent the length change, length, width and thickness of the area respectively. The optical fiber 200 (fiber grating) is bonded to the middle part of the substrate 100 with high temperature glue 4. During the experiment, the substrate 100 and the object to be measured can be fixed with screws through the connecting through holes 5. When the object to be measured generates strain at high temperature, the strain will be transferred to the substrate 100 through the screws, and then transferred from the substrate 100 to the optical fiber 200 through the high temperature glue 4. When the object to be measured is large enough and the stiffness of the sensor is less than the stiffness of the object to be measured, in an ideal case (ignoring the strain loss during installation), Δl 待测 =Δl 基片 , from formula (1), we can know that ε

[0043] 待测 =ε 基片 , while ignoring the thermal expansion and strain transfer loss of the high temperature glue 4 in the thermal environment, then ε 光栅 =ε1, where ε1 is the strain at the grating bonding point.

[0044]

[0045] Let k = l1 / 2l2

[0046]

[0047] ε2=(1+k)ε 待测 -kε1 formula (4);

[0048]

[0049] Where E is the elastic modulus of the material, σ is the stress on the material, ε is the strain value on the material, and the stress value is the force F per unit area S.

[0050] Let ε2 = aε1 and substitute it into formula (4) to obtain:

[0051]

[0052] If S1>S2, from formula (5), we can see that ε1<ε2, that is, a>1, then ε1<ε 待测 , that is, the effect of strain desensitization and range extension is achieved. Let the desensitization coefficient R = ε1 / ε 待测 , where R is related to a (determined by the cross-sectional areas S1 and S2, i.e., the widths W1 and W2 and the thicknesses h1 and h2) and k (determined by the lengths l1 and l2). Therefore, by changing the length and axial cross-sectional area of ​​certain parts on the metal substrate 100, the corresponding desensitization coefficient R can be obtained.

[0053] Based on the above formula, the following structure is designed:

[0054] According to a preferred embodiment of the present application, the substrate 100 forms an elastic ring structure 102 around the hollow area 101, and the elastic ring structure 102 is arranged around the hollow area 101. The entire substrate 100 (including the elastic ring structure 102 and other parts) is an integrally formed part. Preferably, the entire substrate 100 is an elastic substrate 100, and the elastic ring structure 102 is mainly used to bear the strain of the substrate 100 to prevent the substrate 100 from plastic deformation due to excessive strain. The optical fiber 200 grating is bonded to the two ends of the thicker area in the middle of the substrate 100. The elastic ring structure 102 protrudes from both sides of the substrate 100 along the width direction of the substrate 100, and / or protrudes from both sides of the substrate along the thickness direction of the substrate.

[0055] The substrate 100 is provided with a first stretching position 103 and a second stretching position 104 arranged at intervals, and the first stretching position 103 and the second stretching position 104 are both used to connect to the object to be measured, the first connection point of the optical fiber 200 is connected to the first optical fiber connection position 106 on the substrate 100, and the second connection point of the optical fiber 200 is connected to the second optical fiber connection position 107 on the substrate 100, and the first optical fiber connection position, the hollow area 101 and the second optical fiber connection position 107 are sequentially arranged along the length direction of the substrate 100. The packaging method of the sensor includes an optional small strain measurement installation mode and a large strain measurement installation mode. When the packaging method of the sensor is selected as a small strain In the measurement installation mode, the first optical fiber connection position 106 and the second optical fiber connection position 107 are located between the first stretching position 103 and the second stretching position 104; when the packaging method of the sensor is selected as the large strain measurement installation mode, the first stretching position 103 and the second stretching position 104 are located between the first optical fiber connection position 106 and the second optical fiber connection position 107, and the substrate 100 has substrate extension parts 105 on both sides of the first stretching position 103 and the second stretching position 104 along the arrangement direction of the first stretching position 103 and the second stretching position 104, and the first optical fiber connection position 106 and the second optical fiber connection position 107 are respectively located on the corresponding substrate extension parts 105.

[0056] In the small strain measurement installation mode, since the distance between the stretching points is larger than the distance between the bonding points, it is known from formula (1) that if ΔL is the same, L 基片 >L 光栅 , then ε 基片 <ε1, that is, there is a certain strain sensitization effect, which can detect smaller strain amounts at high temperatures.

[0057] In order to further expand the strain measurement range of the fiber Bragg grating strain sensor, the length of the substrate 100 is extended on the side of the stretching hole connecting the through hole 5, and the optical fiber 200 is bonded to both ends of the extended part (i.e., the substrate extension part 105). Since the bonding point is outside the stretching hole (connecting the through hole 5), ΔL 待测 =ΔL 光栅 , it can be seen from formula (7) that the strain transfer coefficient of the strain sensor is completely determined by the spacing between the test points and the grating spacing. The wide and thick part in the middle is to reduce the strain of the test piece transmitted to the elastic ring structure 102 in the middle, thereby increasing the strain that the whole can withstand, and is more suitable for high temperature and large strain measurement environments.

[0058]

[0059] According to a specific embodiment of the present application, both the first stretching position 103 and the second stretching position 104 have connecting through holes 5 for the threaded fasteners 6 to pass through. The first stretching position 103 may have two connecting through holes 5 arranged along the width direction of the substrate 100, and the second stretching position 104 may also have two connecting through holes 5 arranged along the width direction of the substrate 100. The connecting through holes 5 are for threaded fasteners 6 such as screws and bolts to pass through to connect the substrate 100 to the object to be tested 7. Of course, the number of connecting through holes 5 in the first stretching position 103 and the second stretching position 104 is not limited to two.

[0060] In summary, the present application provides a fiber grating strain sensor that can realize strain measurement in a high-temperature environment. The strain transfer coefficient can be controlled by designing the width and thickness of different parts of the structural component. In order to prevent the structural component from undergoing plastic deformation, yielding or even fracture at high temperatures, the elastic ring structure 102 in the middle of the structural component can share the strain on the entire structural component, thereby avoiding the above situation. In order to realize the measurement of small strain or large strain environment at high temperature, the ratio of the spacing between the first stretching position 103 and the second stretching position 104 and the first optical fiber connection position 106 and the second optical fiber connection position 107 can be designed to achieve the effect of increasing sensitivity or decreasing sensitivity and increasing range, thereby realizing the measurement of small strain or large strain environment at high temperature.

[0061] In addition, the present application has found that due to the complexity of the actual application scenario, if the bare fiber 200 grating is directly used for testing in a high temperature and large strain environment, the fiber 200 grating is easily interfered and damaged by the outside world. At the same time, the fiber 200 grating itself has a certain upper limit of strain measurement. Therefore, it is necessary to package the fiber 200 grating on the metal packaging substrate structure for protection, and adjust the appropriate strain transfer coefficient ratio by designing a special structure. However, in general, the thermal expansion coefficient of the metal is greater than the thermal expansion coefficient of the optical fiber 200. Due to the difference in thermal expansion coefficients between the two, as the temperature rises, the optical fiber 200 is continuously stretched or even broken. Therefore, a pre-relaxation method is adopted to make the optical fiber 200 just tightened at the target temperature, thereby realizing the strain measurement at the temperature. According to the requirements of the application scenario, if a small strain of the object to be measured needs to be measured at high temperature, a structural substrate 100 that can improve the sensitivity needs to be designed. If a large strain of the object to be measured needs to be measured at high temperature, a structural substrate 100 with a large range of desensitization needs to be designed.

[0062] It should be noted that the above embodiments only express the preferred implementation of the present application, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the present application. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, such as combining different features in various embodiments, etc., which should all fall within the scope of protection of the present application.

Claims

1. A sensor packaging method, characterized in that: The packaging method of the sensor is implemented for a structure to be packaged, the structure to be packaged includes a substrate and an optical fiber placed on the upper surface of the substrate, a hollow area penetrating the substrate along the thickness direction of the substrate is formed on the substrate, the optical fiber crosses the hollow area above the hollow area, and a tensioning implementation portion is provided on the section of the optical fiber crossing the hollow area; The packaging method of the sensor comprises the following steps: Pre-relaxing the optical fiber, using a pre-tightening adjustment mechanism to pass through the hollow area and allowing the pre-tightening adjustment mechanism to support the tensioning implementation part of the optical fiber in a direction away from the substrate, and stopping the supporting operation after the distance between the tensioning implementation part and the substrate reaches the target pre-relaxation adjustment distance; Optical fiber connection, after the pre-tensioning adjustment mechanism stops the supporting operation, the first connection point of the optical fiber located on one side of the tensioning implementation part and the second connection point on the other side are respectively connected to the upper surface of the substrate, so that the structure to be packaged forms a packaged sensor.

2. The sensor packaging method according to claim 1, characterized in that: The pre-relaxation method includes: determining the target pre-relaxation adjustment distance based on the amount of strain applied to the optical fiber after the optical fiber is raised from an initial temperature to a target temperature, so that the optical fiber in the packaged sensor is stretched to a taut state by the substrate just after the optical fiber is raised from the initial temperature to the target temperature.

3. The sensor packaging method according to claim 1 or 2, characterized in that: The pre-tensioning adjustment mechanism can telescopically move along a direction passing through the hollow area to change the distance between the tensioning implementation position of the optical fiber and the substrate.

4. The sensor packaging method according to claim 3, characterized in that: The pre-tensioning adjustment mechanism comprises a telescopic driving mechanism and a supporting member connected to the telescopic driving mechanism, wherein the supporting member penetrates the hollow area and supports the tensioning implementation position of the optical fiber in a direction away from the substrate.

5. The sensor packaging method according to claim 4, characterized in that: The telescopic driving mechanism is a manual lifting platform or an electric lifting platform.

6. The sensor packaging method according to claim 3, characterized in that: The packaging method also includes: before performing the optical fiber pre-relaxation step, respectively fixing a first pad and a second pad at the lower ends of the substrate on both sides of the hollow area, placing the first pad and the second pad on a workbench, placing the pre-tightening adjustment mechanism on the workbench and positioning the pre-tightening adjustment mechanism below the substrate and between the first pad and the second pad.

7. The sensor packaging method according to claim 1 or 2, characterized in that: The packaging method further comprises: in the optical fiber connection step, the first connection point and the second connection point are respectively glued to the upper surface of the substrate.

8. An optical fiber high temperature strain sensor, characterized in that: The optical fiber high temperature strain sensor is obtained by the packaging method of the sensor according to any one of claims 1 to 7, and the optical fiber high temperature strain sensor is a sensor formed after the structure to be packaged is packaged.

9. The optical fiber high temperature strain sensor according to claim 8, characterized in that: The substrate forms an elastic ring structure around the hollow area, the elastic ring structure is arranged around the hollow area, and the elastic ring structure protrudes from both sides of the substrate along the width direction of the substrate and / or protrudes from both sides of the substrate along the thickness direction of the substrate.

10. The optical fiber high temperature strain sensor according to claim 8, characterized in that: The substrate is provided with a first stretching position and a second stretching position arranged at intervals, and the first stretching position and the second stretching position are both used to connect to the object to be measured, the first connection point of the optical fiber is connected to the first optical fiber connection position on the substrate, and the second connection point of the optical fiber is connected to the second optical fiber connection position on the substrate, and the packaging method of the sensor includes a selectable small strain measurement installation mode and a large strain measurement installation mode. When the packaging method of the sensor is selected as the small strain measurement installation mode, the first optical fiber connection position and the second optical fiber connection position are located between the first stretching position and the second stretching position; when the packaging method of the sensor is selected as the large strain measurement installation mode, the first stretching position and the second stretching position are located between the first stretching position and the second optical fiber connection position, and the substrate has substrate extension parts on both sides of the first stretching position and the second stretching position along the arrangement direction of the first stretching position and the second stretching position, and the first optical fiber connection position and the second optical fiber connection position are respectively located on the corresponding substrate extension parts.

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