Packaging method of sensor and optical fiber high temperature strain sensor

Abstract

The application relates to the technical field of optical fiber sensors, and provides a sensor packaging method and an optical fiber high-temperature strain sensor, wherein the sensor packaging method is implemented for a to-be-packaged structure, the to-be-packaged structure comprises a substrate and an optical fiber, the substrate is provided with a hollow area, the optical fiber is arranged above the hollow area and spans the hollow area, and the optical fiber is provided with a tensioning implementation part on a section of the optical fiber that spans the hollow area; the sensor packaging method comprises the following steps: optical fiber pre-relaxation, a pre-tightening adjusting mechanism is used to support the tensioning implementation part of the optical fiber, and the supporting operation is stopped after the distance between the tensioning implementation part and the substrate reaches a target pre-relaxation adjusting distance; optical fiber connection, a first connecting point on one side of the tensioning implementation part of the optical fiber and a second connecting point on the other side of the optical fiber are connected to the upper surface of the substrate respectively, and the sensor packaging method can solve the technical problem that the optical fiber in an optical fiber grating sensor in the prior art is prone to breaking at high temperatures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber sensor, in particular to a sensor packaging method and an optical fiber high-temperature strain sensor. BACKGROUND

[0002] With the rapid development of various high-speed aircraft, the service aerodynamic thermal environment is becoming more and more severe. The heat protection problem caused by the severe aerodynamic thermal environment has become one of the problems restricting the development of high-speed aircraft. The response characteristics of heat protection materials in high-temperature environment are the basis of the thermal protection design of aircraft. Accurate measurement of the thermal performance of heat protection materials in high-temperature environment has important guiding significance for the design of thermal structure. Optical fiber sensor is a new generation of sensor, which has the advantages of small size, light weight, high temperature resistance, corrosion resistance, anti-electromagnetic interference, distributed measurement points, easy networking and multi-parameter simultaneous measurement. Therefore, high-temperature resistant optical fiber material is very suitable for measuring high-temperature strain environment.

[0003] Optical fiber grating sensor can be used for sensing and measuring physical quantities such as stress, strain or temperature, and has high sensitivity and measurement range. By writing optical fiber gratings with different grating pitches at several positions of the optical fiber, the corresponding physical quantities and their changes at several positions can be measured simultaneously, and quasi-distributed optical fiber sensing can be realized. In summary, the application of optical fiber grating sensor is a burgeoning field with very broad development prospects. The optical fiber sensor in the prior art has the disadvantages of plastic deformation, yield and even fracture at high temperature, and cannot measure high-temperature strain at high temperature. It is usually only suitable for strain measurement at room temperature. Moreover, the thermal expansion coefficient of general metal is much larger than that of optical fiber. At high temperature, the optical fiber will be stretched or even broken due to the difference in thermal expansion coefficient between the two. SUMMARY

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

[0005] The present application provides a sensor packaging method, wherein the sensor packaging method is implemented for a to-be-packaged structure, the to-be-packaged structure includes a substrate and an optical fiber placed on the upper surface of the substrate, the substrate is formed with a hollow area penetrating through the substrate along the thickness direction of the substrate, the optical fiber spans the hollow area above the hollow area, and the section of the optical fiber spanning the hollow area has a tensioning implementation site.

[0006] The sensor packaging method includes the following steps:

[0007] pre-tensioning adjusting mechanism is stopped from supporting the tensioning implementation position of the optical fiber in a direction away from the substrate, and the distance between the tensioning implementation position and the substrate reaches a target pre-relaxation adjustment distance;

[0008] optical fiber connection, after the pre-tensioning adjusting mechanism is stopped from supporting, the first connection point and the second connection point on the two sides of the tensioning implementation position of the optical fiber are connected to the upper surface of the substrate respectively, so that the to-be-packaged structure forms a packaged sensor.

[0009] Further, the pre-relaxation method comprises: determining the target pre-relaxation adjustment distance based on the amount of strain that the optical fiber is subjected to after the optical fiber is raised from an initial temperature to a target temperature, so that the optical fiber in the packaged sensor is just stretched to a taut state by the substrate after being raised from the initial temperature to the target temperature.

[0010] Further, the pre-tensioning adjusting mechanism is capable of telescopic movement in a direction through the hollowed-out area to change the distance between the tensioning implementation position of the optical fiber and the substrate.

[0011] Further, the pre-tensioning adjusting mechanism comprises a telescopic driving mechanism and a supporting piece connected to the telescopic driving mechanism, and the supporting piece passes through the hollowed-out area and supports the tensioning implementation position of the optical fiber in a direction away from the substrate.

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

[0013] Further, the packaging method further comprises: before the optical fiber pre-relaxation step, fixing a first pad and a second pad respectively at the lower ends of the two sides of the substrate in the hollowed-out area, placing the first pad and the second pad on a workbench, placing the pre-tensioning adjusting mechanism on the workbench and below the substrate and between the first pad and the second pad.

[0014] Further, 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 application also provides an optical fiber high-temperature strain sensor, wherein the optical fiber high-temperature strain sensor is obtained by the packaging method of the sensor, and the optical fiber high-temperature strain sensor is the sensor formed after the to-be-packaged structure is packaged.

[0016] Further, the substrate forms an elastic ring structure around the hollowed-out area, the elastic ring structure is arranged around the hollowed-out area, 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] Further, the substrate is provided with a first stretch site and a second stretch site arranged at intervals, the first stretch site and the second stretch site are both used for connecting to the measured body, the first connecting point of the optical fiber is connected to the first optical fiber connecting site on the substrate, the second connecting point of the optical fiber is connected to the second optical fiber connecting site on the substrate, 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 connecting site and the second optical fiber connecting site are located between the first stretch site and the second stretch site; when the packaging method of the sensor is selected as the large strain measurement installation mode, the first stretch site and the second stretch site are located between the first optical fiber connecting site and the second optical fiber connecting site, and the substrate has a substrate extension part on both sides of the first stretch site and the second stretch site along the arrangement direction of the first stretch site and the second stretch site, and the first optical fiber connecting site and the second optical fiber connecting site are located on the corresponding substrate extension part respectively.

[0018] Compared with the prior art, in the packaging method of the sensor, a fiber pre-relaxation step is performed for the structure to be packaged, that is, the pre-tightening adjusting mechanism is passed through the hollowed-out area and the pre-tightening adjusting mechanism supports the tensioning implementation part of the optical fiber in a direction away from the substrate, and the distance between the tensioning implementation part and the substrate is stopped after reaching the target pre-relaxation adjustment distance. In this way, the target pre-relaxation adjustment distance can be determined according to actual needs, the relaxation degree of the section of the optical fiber between the first connecting point and the second connecting point can be flexibly adjusted according to actual needs, the strain of the optical fiber at high temperature is prevented from being too large to cause the optical fiber to break, specifically, the phenomenon that the optical fiber is continuously stretched by the metal or even breaks due to the difference in thermal expansion coefficient between the optical fiber and the metal as the temperature rises is avoided, the target pre-relaxation adjustment distance can be determined based on the size of the strain of the optical fiber after the optical fiber is raised from the initial temperature to the target temperature, the optical fiber is just stretched to a tight state at a certain temperature point, high-sensitivity or large-range strain measurement at high temperature is realized, and specifically, the displacement amount of the pre-tightening adjusting mechanism can be determined by theoretically calculating the size of the strain of the optical fiber raised to the target temperature to match the relaxation degree of the required optical fiber.

[0019] Other advantages of the present application will be described in more detail in the following specific embodiment part. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on these drawings.

[0021] Figure 1 A perspective view of a fiber high-temperature strain sensor in a packaging process according to an embodiment of the present application;

[0022] Figure 2 A perspective view of a fiber high-temperature strain sensor in a packaging process according to an embodiment of the present application; Figure 1 An enlarged view of A in FIG. 6;

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

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

[0025] Figure 5 A structural design principle diagram of a 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 fully below with reference to the accompanying drawings. The accompanying drawings show one or more embodiments of the present application to make the understanding of the technical solutions disclosed by the present application more accurate and thorough. However, it should be understood that the present application can be realized in various forms, and is not limited to the embodiments described below.

[0027] In the drawings of the present application, the same or similar reference numerals correspond to the same or similar components; in the description of the present application, it should be understood that the orientations or positional relationships indicated by terms such as "upper", "lower", "left", "right" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present application, for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0028] In addition, if the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features. In addition, if "and / or" or "and / or" appears throughout the text, it means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B scheme.

[0029] In addition, the technical solutions among various embodiments can be combined with each other, but it must be based on that a person skilled in the art can realize it, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.

[0030] Referring to Figures 1 to 4 According to one aspect of the present application, 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, the substrate 100 is formed with a hollow area 101 penetrating through the substrate 100 along the thickness direction of the substrate 100, the optical fiber 200 spans the hollow area 101 above the hollow area 101, and the optical fiber 200 has a tensioning implementation part 201 on the section of the optical fiber 200 spanning 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 sensor packaging method includes the following steps:

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

[0033] The optical fiber is connected, after the pre-tightening adjusting mechanism 300 stops the supporting operation, the first connection point on one side of the tensioning implementation part 201 of the optical fiber 200 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, the optical fiber is pre-relaxed before being packaged, that is, the pre-tightening adjusting mechanism 300 is passed through the hollow area 101 and props the tensioning implementation part 201 of the optical fiber 200 away from the substrate 100, and the pre-tightening adjusting mechanism 300 is stopped from propping when the distance between the tensioning implementation part 201 and the substrate 100 reaches the target pre-relaxation adjustment distance. In this way, the target pre-relaxation adjustment distance can be set according to actual needs, the 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, the strain of the optical fiber 200 at high temperature is prevented from being too large to cause the optical fiber 200 to break, and specifically, the phenomenon that the optical fiber 200 is continuously stretched by the metal or even breaks as the temperature rises due to the difference in the thermal expansion coefficient between the optical fiber 200 and the metal is avoided. The target pre-relaxation adjustment distance can be determined based on the size of the strain of 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 just stretched to a taut state by the substrate 100 at a certain temperature point, and strain measurement at high temperature with high sensitivity or a large range is realized. Specifically, the displacement of the pre-tightening adjusting mechanism 300 can be determined by theoretically calculating the size of the strain of the optical fiber 200 raised to the target temperature to match the relaxation degree of the optical fiber 200 required.

[0035] As mentioned above, the pre-relaxation method can include the step of determining the target pre-relaxation adjustment distance based on the size of the strain of 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 just stretched to a taut state by the substrate 100 after being raised from the initial temperature to the target temperature. Of course, as other embodiments, the target pre-relaxation adjustment distance can also be determined according to experience data table or built database one by one.

[0036] According to specific embodiments of the present application, the pre-tightening adjusting mechanism 300 can be telescopically moved in the direction 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 pre-tightening adjusting mechanism 300 includes a telescopic driving mechanism and a prop 301 connected to the telescopic driving mechanism, the prop 301 passes through the hollow area 101 and props the tensioning implementation part 201 of the optical fiber 200 away from the substrate 100, and the prop 301 can be a prop block, a prop rod or the like, and the end face of the prop 301 away from the telescopic driving mechanism props the tensioning implementation part 201 of the optical fiber 200. In order to prevent the optical fiber 200 from slipping off the prop 301, the end face of the prop 301 away from the telescopic driving mechanism can also form a limiting groove in which the optical fiber 200 is accommodated, or the width of the prop 301 can be much larger than the diameter of the optical fiber 200.

[0038] According to the specific embodiments of the present application, the telescopic driving mechanism is a manual lifting platform or an electric lifting platform, or the pre-tightening adjustment mechanism 300 is a micro electric push rod, and it is also possible that the tip of the piston rod of the micro electric push rod supports the optical fiber 200, since the manual lifting platform, the electric lifting platform and the micro electric push rod can all adopt known mechanisms.

[0039] Further, the manual lifting platform can include a base 302, a lifting seat 303 connected to the base 302 through a lifting assembly, and a supporting piece 301 connected above the lifting seat 303. The lifting assembly can include two groups of plug-in arm link mechanisms, each of which includes a first link 304, a second link 305, a third link 306 and a fourth link 307, the upper ends of the first link 304 and the fourth link 307 are hinged to each other and to the lifting seat 303, the lower end of the first link 304 and the upper end of the second link 305 are hinged to each other and to a first sliding seat 308, the lower end of the second link 305 and the lower end of the third link 306 are hinged to each other and to the base 302, the upper end of the third link 306 and the lower end of the fourth link 307 are hinged to each other and to a second sliding seat 309, and the manual lifting platform can further include a rotatable adjustment rod 310 threadedly matched with the first sliding seat 308 and the second sliding seat 309. By turning the rotatable adjustment rod 310, 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 adjustment rod 310 based on the principle similar to that of a screw nut, so as to control the opening and closing degree of the plug-in arm link mechanism, and thus make the lifting seat 303 lift relative to the base 302.

[0040] According to the specific embodiments of the present application, the packaging method further includes: before the optical fiber pre-relaxation step, fixing a first pad 1 and a second pad 2 respectively at the lower ends of the two sides of the base plate 100 located in the hollowed-out area 101, placing the first pad 1 and the second pad 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 base plate 100 and between the first pad 1 and the second pad 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 base plate 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 application, 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 sensor, the optical fiber high-temperature strain sensor is a sensor formed after packaging of the to-be-packaged structure, and the optical fiber high-temperature strain sensor is an optical 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 a Faraday-Michelson interferometer principle, an optical fiber sensor based on a Mach-Zehnder interferometer principle, etc., wherein the optical fiber FP structure, also known as a contra resonant optical fiber (FP optical fiber), is a special optical fiber structure, the cavity length of the optical fiber core part is adjusted to be equal to half of the reflection wavelength, so that the peak and valley are eliminated by reflection, and the resonance phenomenon is suppressed.

[0042] Referring to Figure 5 , Δl, L, W, h respectively represent the length change, length, width and thickness of the region. The optical fiber 200 (optical fiber grating) is bonded to the middle part of the substrate 100 by using high-temperature glue 4. In the experiment, the substrate 100 and the object to be measured can be fixed by using a screw to pass through the connecting through hole 5, when the object to be measured generates strain under high temperature, the strain will be transmitted to the substrate 100 through the screw, and then transmitted to the optical fiber 200 through the high-temperature glue 4 of the substrate 100. When the measured object is large enough, the rigidity of the sensor is smaller than the rigidity of the object to be measured, and in the ideal case (ignoring the strain loss during installation), then Δl 待测 = Δl 基片 , it can be seen from formula (1) that ε 待测 = ε 基片 , and the thermal expansion amount and strain transmission loss of the high-temperature glue 4 in the thermal environment are ignored, then ε 光栅 = ε1, wherein ε1 is the strain value at the bonding position of the grating.

[0043]

[0044] Let k = l1 / 2l2

[0045]

[0046] ε2 = (1 + k) ε 待测 -kε1 formula (4);

[0047]

[0048] Wherein E is the elastic modulus of the material, σ is the stress suffered by the material, and ε is the strain value suffered by the material. The stress value is the force F suffered by the unit area S.

[0049] Let ε2 = aε1, substitute formula (4) to obtain:

[0050]

[0051] If S1>S2, according to formula (5), ε1<ε2, i.e. a>1, then ε1<ε 待测 i.e. the effect of strain reduction and range expansion is achieved. Let the reduction coefficient R = ε1 / ε 待测 wherein R is related to a (determined by the cross-sectional area S1, S2, i.e. determined by the width W1, W2 and the thickness h1, h2) and k (determined by the length l1, l2), therefore, by changing the length and the axial cross-sectional area of some parts of the metal substrate 100, the corresponding reduction coefficient R can be obtained.

[0052] Based on the above formula, the following structure is designed:

[0053] According to the preferred embodiment of the present application, the substrate 100 forms an elastic ring structure 102 around the hollowed-out area 101, the elastic ring structure 102 is arranged around the hollowed-out area 101, and the entire substrate 100 (including the elastic ring structure 102 and other parts) is a one-piece molded part, and 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, so as to avoid plastic deformation of the substrate 100 due to excessive strain. The fiber grating 200 is bonded at both ends of the relatively thick region in the middle of the substrate 100. The elastic ring structure 102 protrudes from both sides of the substrate 100 in the width direction of the substrate 100, and / or protrudes from both sides of the substrate in the thickness direction of the substrate.

[0054] The first and second stretching positions 103 and 104 are arranged at intervals on the substrate 100, and the first and second stretching positions 103 and 104 are both used to be connected to the measured body. 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. The first optical fiber connection position, the hollowed-out area 101 and the second optical fiber connection position 107 are arranged in sequence along the length direction of the substrate 100. 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 and second optical fiber connection positions 106 and 107 are located between the first and second stretching positions 103 and 104. When the packaging method of the sensor is selected as the large strain measurement installation mode, the first and second stretching positions 103 and 104 are located between the first and second optical fiber connection positions 106 and 107, and the substrate 100 has a substrate extension part 105 on both sides of the first and second stretching positions 103 and 104 along the arrangement direction of the first and second stretching positions 103 and 104, and the first and second optical fiber connection positions 106 and 107 are located on the corresponding substrate extension parts 105, respectively.

[0055] In the small strain measurement installation mode, since the distance between the stretching points is larger than the distance between the bonding points, according to formula (1), if ΔL is the same, and 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 at high temperature.

[0056] In order to further expand the strain measurement range of the fiber grating strain sensor, the length of the substrate 100 is lengthened on the side of the stretching hole connected to the through hole 5, and the optical fiber 200 is bonded to both ends of the lengthened part (i.e., the substrate extension part 105). Since the bonding points are outside the stretching hole (the through hole 5), ΔL 待测 = ΔL 光栅 According to formula (7), the strain transfer coefficient of the strain sensor at this time depends entirely on the distance between the points to be measured and the grating distance. The wide and thick middle part is to reduce the strain of the measured object transferred to the elastic ring structure 102 in the middle, thereby increasing the strain that the whole structure can withstand, and more suitable for high-temperature and large-strain measurement environments.

[0057]

[0058] According to specific embodiments of the present application, the first stretching site 103 and the second stretching site 104 each have a connecting through hole 5 for the threaded fastener 6 to pass through. The first stretching site 103 can have two connecting through holes 5 arranged along the width direction of the substrate 100, and the second stretching site 104 can also have two connecting through holes 5 arranged along the width direction of the substrate 100. The connecting through hole 5 is for a screw, bolt or other threaded fastener 6 to pass through to connect the substrate 100 to the measured object 7. Of course, the number of connecting through holes 5 of the first stretching site 103 and the second stretching site 104 is not limited to two.

[0059] In summary, the present application provides a fiber grating strain sensor that can realize strain measurement in a high-temperature environment. The width and thickness of different parts of the structure can be designed to control the strain transfer coefficient. To prevent plastic deformation, yield or even rupture of the structure at high temperature, the elastic ring structure 102 in the middle of the structure can share the strain of the overall structure, thereby avoiding the above situations. In order to realize small strain or large strain measurement in a high-temperature environment, the ratio of the distance between the first stretching site 103 and the second stretching site 104 and the distance between the first optical fiber connecting site 106 and the second optical fiber connecting site 107 can be designed to achieve the effect of sensitization or desensitization and range expansion, and to realize small strain or large strain measurement in a high-temperature environment.

[0060] In addition, the application finds that, due to the complexity of the actual application scene, if the bare fiber 200 grating is directly used for testing in a high-temperature and large-strain environment, the fiber 200 grating is easy to be interfered and damaged by the outside world, and the fiber 200 grating itself has a certain upper limit of strain measurement, so it is necessary to encapsulate the fiber 200 grating on the metal packaging substrate structure for protection, and adjust the appropriate strain transmission coefficient ratio through the design of a special structure. However, in general, the thermal expansion coefficient of the metal is greater than that of the fiber 200, and due to the difference between the two thermal expansion coefficients, the fiber 200 is continuously stretched and even broken as the temperature rises, so a pre-relaxation method is adopted to make the fiber 200 be just stretched at the target temperature, so as to realize the strain measurement at the temperature, and according to the requirements of the application scene, if the small strain of the measured object needs to be measured at high temperature, a structure substrate 100 with high sensitivity needs to be designed, and if the large strain of the measured object needs to be measured at high temperature, a structure substrate 100 with large range of sensitivity reduction needs to be designed.

[0061] It should be noted that the above embodiments only express the preferred embodiments of the application, and the description is more specific and detailed, but it should not be construed as a limitation of the application. It should be noted that for those skilled in the art, without departing from the concept of the application, a number of modifications and improvements can be made, such as the combination of different features in each embodiment, which should belong to the protection scope of the application.

Claims

1. A method for packaging a sensor, characterized in that, The sensor encapsulation method is implemented for a structure to be encapsulated, the structure to be encapsulated includes a substrate and an optical fiber placed on the upper surface of the substrate. A hollow area is formed on the substrate that extends through the substrate along the thickness direction. The optical fiber crosses the hollow area above the hollow area, and the section of the optical fiber that crosses the hollow area has a tensioning implementation part. The sensor packaging method includes the following steps: Fiber pre-relaxation involves using a pre-tightening adjustment mechanism to pass through the hollow area and push the tensioning implementation part of the fiber in a direction away from the substrate until the distance between the tensioning implementation part and the substrate reaches the target pre-relaxation adjustment distance, at which point the pushing operation stops. After the pre-tightening adjustment mechanism stops its supporting operation, the first connection point on one side of the tensioning implementation part and the second connection point on the other side of the optical fiber are respectively connected to the upper surface of the substrate so that the structure to be packaged forms the packaged sensor. The pre-relaxation method includes: determining the target pre-relaxation adjustment distance based on the magnitude of the strain experienced by the optical fiber after the initial temperature rises to the target temperature, so that the optical fiber in the packaged sensor is just stretched to a taut state by the substrate after the initial temperature rises to the target temperature; The pre-tensioning adjustment mechanism can extend and retract along the direction through the hollow area to change the distance between the tensioning part of the optical fiber and the substrate; The pre-tensioning adjustment mechanism includes a telescopic drive mechanism and a top support connected to the telescopic drive mechanism. The top support penetrates the hollow area and supports the tensioning implementation part of the optical fiber in a direction away from the substrate.

2. The sensor packaging method according to claim 1, characterized in that, The telescopic drive mechanism is a manual lifting platform or an electric lifting platform.

3. The sensor packaging method according to claim 1, characterized in that, The encapsulation method further includes: before performing the fiber pre-relaxation step, fixing a first pad and a second pad respectively at the lower ends of the substrate on both sides of the hollow area, placing the first pad and the second pad on a worktable, placing the pre-tightening adjustment mechanism on the worktable and positioning the pre-tightening adjustment mechanism below the substrate and between the first pad and the second pad.

4. The sensor packaging method according to claim 1, characterized in that, The encapsulation method further includes: 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.

5. A fiber optic high-temperature strain sensor, characterized in that, The fiber optic high-temperature strain sensor is obtained by the packaging method of the sensor according to any one of claims 1 to 4, and the fiber optic high-temperature strain sensor is a sensor formed after the structure to be packaged is packaged.

6. The fiber optic high-temperature strain sensor according to claim 5, 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 protrudes from both sides of the substrate along the width direction and / or along the thickness direction of the substrate.

7. The fiber optic high-temperature strain sensor according to claim 5, characterized in that, The substrate has a first tension position and a second tension position arranged at intervals. Both the first tension position and the second tension position are used to connect to the object being 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. The sensor packaging method includes a selectable small strain measurement installation mode and a large strain measurement installation mode. When the sensor packaging method 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 tension position and the second tension position. When the sensor packaging method is selected as the large strain measurement installation mode, the first tension position and the second tension position are located between the first optical fiber connection position and the second optical fiber connection position. The substrate has substrate extension portions on both sides of the first tension position and the second tension position along the arrangement direction of the first tension position and the second tension position. The first optical fiber connection position and the second optical fiber connection position are located on the corresponding substrate extension portions.

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