A strain gauge based on white light interference principle

Abstract

The present disclosure relates to a strain gauge based on the principle of white light interference. The strain gauge is arranged to be fixed on the surface of the measured object to measure the strain of the object under the corresponding load, and the strain gauge is provided with a first fixed part, a second fixed part and an elastic deformation part arranged between the first fixed part and the second fixed part, and the strain gauge is arranged to be fixedly connected with the measured object through the first fixed part and the second fixed part; wherein the elastic deformation part is arranged to be elastically compressed or stretched along the axial direction of the elastic deformation part; the elastic deformation part is configured to have an axially symmetric stress release hole, and one or more pairs of axially symmetric deformation stabilizing retaining holes for stabilizing the interference cavity strain of the strain gauge when the elastic deformation part is elastically compressed or stretched in the axial direction. Some embodiments of the present disclosure aim to ensure nanoscale precision measurement while eliminating tracking errors in principle, so that the strain sensor has high precision and stable performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber sensing, in particular to a strain gauge based on white light interference principle. BACKGROUND

[0002] The strain gauge or in some application scenarios is called a strain sensor, which is a kind of sensing device for monitoring the strain of an object. Generally, the strain gauge is usually fixed on the surface of the measured object by means of glue, welding, bolts, etc. When the surface of the object produces strain, the strain can be transmitted to the strain gauge, which in turn causes the output signal of the strain gauge to change, thereby realizing the measurement of the strain. Generally, the strain sensor includes an electronic strain gauge, a vibrating wire strain gauge, and a fiber Bragg grating strain gauge. The electronic strain gauge realizes strain measurement through the internal resistance strain gauge of the sensor; the vibrating wire strain gauge changes the natural frequency of the vibrating wire after being affected by external strain, thereby realizing strain measurement; and the fiber Bragg grating strain gauge changes the reflection wavelength when the grating is externally stretched, thereby realizing strain measurement. These technologies have the following defects: poor long-term stability, creep, drift, and other phenomena occur in the electronic strain gauge, vibrating wire, and fiber Bragg grating during long-term use, which reduces the performance of the sensor. The resistance strain gauge and the vibrating wire strain gauge are active devices, which are easily affected by electromagnetic interference and prone to zero drift in long-term operation. The fiber Bragg grating strain gauge has low resolution and poor accuracy due to the limitation of the fiber grating stretch. The white light interference technology has the advantages of non-contact, high precision, and anti-electromagnetic interference, but its application in strain measurement is limited by the sensor structure design and installation process. At present, the strain sensor based on this principle has the following problems, for example, when the strain sensor is installed on the surface of the measured object, the sensor structure produces strain or displacement with the measured object. The white light interference technology has high requirements for the position and direction between the incident light and the interference surface, and when the sensor structure deforms, the light interference is easily invalid.

[0003] Therefore, the prior art still needs to be improved and enhanced.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of clearly and completely describing the technical scheme of the present application and facilitating the understanding of those skilled in the art. The above technical scheme cannot be considered as known to those skilled in the art merely because it is described in the background section of the present application. SUMMARY

[0005] In order to solve one or more of the above technical problems, the present disclosure provides a strain gauge based on white light interference principle, which aims to realize nanoscale ultra-high precision measurement and eliminate tracking error in principle, thereby making the strain sensor have high precision and long-term stability.

[0006] In a first aspect of the present disclosure, a strain gauge based on white light interference principle is provided, which is arranged to be fixed on the surface of an object to be measured to measure the strain of the object under corresponding load. The strain gauge is provided with a first fixing part, a second fixing part, and an elastic deformation part arranged between the first fixing part and the second fixing part. The strain gauge is arranged to be fixedly connected with the object to be measured through the first fixing part and the second fixing part. The elastic deformation part is arranged to be elastically compressed or stretched along the axis of the elastic deformation part. The elastic deformation part is configured to have an axially symmetric stress release hole and one or more pairs of axially symmetric deformation stabilizing holding holes for stabilizing the strain of the interference cavity of the strain gauge when the elastic deformation part is elastically compressed or stretched in the axial direction.

[0007] Further, in some embodiments, the strain gauge further comprises a first reference arm configured to extend from one side vertical edge of the stress release hole to the first fixing part and connected with the first fixing part, and the axis of the first reference arm is configured to coincide with the axis of the elastic deformation part; and a second reference arm configured to extend from the other side vertical edge of the stress release hole to the second fixing part and connected with the second fixing part, and the axis of the second reference arm is configured to coincide with the axis of the elastic deformation part.

[0008] Further, in some embodiments, the axially symmetric stress release hole is configured to be axially symmetric with respect to the axis of the elastic deformation part; and the two deformation stabilizing holding holes in each pair of deformation stabilizing holding holes are arranged to be axially symmetric with respect to the axis of the elastic deformation part.

[0009] Further, in some embodiments, the elastic deformation part is configured to have an upper quadrilateral structure and a lower quadrilateral structure which are axially symmetric with respect to the axis of the elastic deformation part; the upper quadrilateral structure is configured to have a first lower horizontal edge parallel to and close to the axis of the elastic deformation part, and a first upper horizontal edge opposite to and parallel to the first lower horizontal edge; and the lower quadrilateral structure is configured to have a second upper horizontal edge parallel to and close to the axis of the elastic deformation part, and a second lower horizontal edge opposite to and parallel to the second upper horizontal edge.

[0010] Further, in some embodiments, the axis of the elastic deformation part is arranged to pass through the first lower horizontal edge and the second upper horizontal edge, so that the first lower horizontal edge coincides with the second upper horizontal edge.

[0011] Further, in some embodiments, the deformation-stable holding hole is configured as a bone-like structure or an I-like structure, and when the elastic deformation portion is elastically compressed or stretched in the axial direction, the upper horizontal edge of the deformation-stable holding hole arranged in the upper quadrilateral structure is parallel to the first upper horizontal edge, and the lower horizontal edge of the deformation-stable holding hole arranged in the lower quadrilateral structure is parallel to the second lower horizontal edge.

[0012] Further, in some embodiments, when the elastic deformation portion is configured with a pair of deformation-stable holding holes, the two deformation-stable holding holes are arranged in axial symmetry with respect to the axis of the elastic deformation portion, one of the two deformation-stable holding holes is arranged in the upper quadrilateral structure, and the other of the two deformation-stable holding holes is arranged in the lower quadrilateral structure; the upper horizontal edge of the deformation-stable holding hole arranged in the upper quadrilateral structure is arranged close to and parallel to the first upper horizontal edge, and the lower horizontal edge of the deformation-stable holding hole arranged in the lower quadrilateral structure is arranged close to and parallel to the second lower horizontal edge.

[0013] Further, in some embodiments, when the elastic deformation portion is configured with two pairs of deformation-stable holding holes, the first and second deformation-stable holding holes of the four deformation-stable holding holes are arranged in the upper quadrilateral structure, and the third and fourth deformation-stable holding holes of the four deformation-stable holding holes are arranged in the lower quadrilateral structure; the upper horizontal edge of the first deformation-stable holding hole is arranged close to and parallel to the first upper horizontal edge, and the upper horizontal edge of the second deformation-stable holding hole is arranged close to and parallel to the first upper horizontal edge, and the first and second deformation-stable holding holes are divided by the upper half of the stress release hole in the upper quadrilateral structure; the lower horizontal edge of the third deformation-stable holding hole is arranged close to and parallel to the second lower horizontal edge, and the lower horizontal edge of the fourth deformation-stable holding hole is arranged close to and parallel to the second lower horizontal edge, and the third and fourth deformation-stable holding holes are divided by the lower half of the stress release hole in the upper quadrilateral structure.

[0014] Further, in some embodiments, the stress release hole is configured as a bone-like structure or an I-like structure, the upper horizontal edge of the stress release hole is arranged close to and parallel to the first upper horizontal edge, and the lower horizontal edge of the stress release hole is arranged close to and parallel to the second lower horizontal edge; the longitudinal axis of the stress release hole passes through and is perpendicular to the axis of the elastic deformation portion.

[0015] Further, in some embodiments, when the elastic deformation part is elastically compressed or stretched along the axial direction, the upper horizontal edge of the stress release hole is parallel to the first upper horizontal edge, and the lower horizontal edge of the stress release hole is parallel to the second lower horizontal edge.

[0016] Further, in some embodiments, the first fixed part is provided as a first upper fixed part and a first lower fixed part, and the fixed end surface of the first upper fixed part and the fixed end surface of the first lower fixed part are separately arranged but in the same plane; the second fixed part is provided as a second upper fixed part and a second lower fixed part, and the fixed end surface of the second upper fixed part and the fixed end surface of the second lower fixed part are separately arranged but in the same plane.

[0017] Further, in some embodiments, the first fixed part and the second fixed part are connected to the measured object by spot welding.

[0018] Further, in some embodiments, a collimating ferrule is fixed inside the first reference arm, the collimating ferrule is arranged to fix the optical fiber collimator inside the ceramic ferrule, and the light emitting end surface of the collimating ferrule is arranged to face the second reference arm; a reflecting ferrule is fixed inside the second reference arm, and the reflecting end surface of the reflecting ferrule is arranged to face the first reference arm.

[0019] Further, in some embodiments, the central axis of the collimating ferrule coincides with the central axis of the reflecting ferrule, and the central axis of the collimating ferrule and the central axis of the reflecting ferrule are perpendicular to the light emitting end surface of the collimating ferrule and the reflecting end surface of the reflecting ferrule.

[0020] Further, in some embodiments, the light emitting end surface of the collimating ferrule and the reflecting end surface of the reflecting ferrule are close to each other, so that a white light interference cavity is formed between the light emitting end surface of the collimating ferrule and the reflecting end surface of the reflecting ferrule, the white light interference cavity is arranged to pass through the stress release hole, and the central axis of the white light interference cavity coincides with the axis of the elastic deformation part.

[0021] The beneficial effects of the present disclosure are:

[0022] 1) In some embodiments, the elastic deformation part of the strain gauge based on white light interference principle is arranged to be elastically compressed or stretched along the axial direction of the elastic deformation part, and the arrangement in some embodiments can ensure stable light path during detection, more uniform intensity distribution of the light beam, more regular spot shape, improve coupling efficiency, reduce loss of optical signal, and improve white light interference efficiency and accuracy.

[0023] 2) In some other embodiments, the elastic deformation part is configured to have axially symmetric stress release holes, and one or more pairs of deformation stabilizing holding holes arranged axially symmetrically for stabilizing the interference cavity strain of the strain gauge when the elastic deformation part is axially elastically compressed or stretched, thereby greatly improving the stability of white light interference of the strain gauge during deformation.

[0024] 3) In further embodiments, the measured object and the strain gauge are fixedly connected by spot welding, which can ensure the reliability and firmness of the strain gauge installation. Further, the fixed part is provided with a separate fixed end, for example, by providing a groove structure on the spot welding sheet, which not only makes the strain gauge installation more convenient, but also weakens the rigidity to enable it to absorb a part of the deformation that is not conducive to the stability of the light interference. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and other features, advantages, and aspects of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings, in which:

[0026] Figure 1 A schematic diagram of a strain gauge based on the principle of white light interference according to an embodiment of the present disclosure is shown;

[0027] Figure 2 A schematic diagram of Figure 1 the line structure extraction of the elastic deformation part in the middle is shown;

[0028] Figure 3 A schematic diagram of another strain gauge based on the principle of white light interference according to an embodiment of the present disclosure is shown;

[0029] Figure 4 A schematic diagram of a strain gauge based on the principle of white light interference according to an embodiment of the present disclosure is shown from another perspective;

[0030] Figure 5 A schematic diagram of Figure 1 some specific structures of the elastic deformation part in the middle are shown;

[0031] Figure 6 A schematic diagram of Figure 1 the line structure extraction of the elastic deformation part during stretching deformation is shown;

[0032] Figure 7 A schematic diagram of a strain gauge based on Figure 2 the additional fixed point in the embodiment is shown; and

[0033] In each of the drawings, the same or corresponding reference numerals represent the same or corresponding parts. DETAILED DESCRIPTION

[0034] Embodiments of the present disclosure will be described below in greater detail with reference to the accompanying drawings. While certain embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so as to more completely and thoroughly understand the present disclosure. It is understood that the drawings and embodiments of the present disclosure are for exemplary purposes only and are not intended to limit the scope of protection of the present disclosure.

[0035] In the description of embodiments of the present disclosure, the term "includes" and its derivatives, such as "including," should be understood in an open, inclusive sense, that is, "including, but not limited to." The term "based on" should be understood as "based at least in part on." The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment." The terms "first," "second," etc. can refer to different or the same objects. Other explicit or implicit definitions can also be included below.

[0036] To solve at least one of the above problems, and one or more of other potential problems, example embodiments of the present disclosure propose a strain gauge based on white light interference principle.

[0037] Specifically, the following is described in detail in conjunction with the drawings.

[0038] Figure 1 A schematic diagram of a strain gauge based on white light interference principle according to an embodiment of the present disclosure is shown. In this illustrated embodiment, the strain gauge 100 based on white light interference principle mainly includes: a first fixed part 10, a second fixed part 20, an elastic deformation part 30. Generally, the strain gauge 100 is arranged to be fixed on the surface of the measured object (not shown) to measure the strain of the object under the corresponding load, the elastic deformation part 30 of the strain gauge 100 is arranged between the first fixed part 10 and the second fixed part 20, and the strain gauge 100 is arranged to be fixedly connected with the measured object (not shown) through the first fixed part 10 and the second fixed part 20; wherein the elastic deformation part 30 can be elastically compressed or stretched along the axial direction of the elastic deformation part 30. Further, as shown, the elastic deformation part 30 is configured to have a stress release hole 31 and two pairs (four in total) of deformation stable holding holes 32, wherein the stress release hole 31 is axially symmetric with respect to the center axis, and the deformation stable holding hole 32 is used to stabilize the strain of the interference cavity of the strain gauge when the elastic deformation part is elastically compressed or stretched in the axial direction, and the deformation stable holding hole 32 is also arranged axially symmetrically with respect to the center axis. It should be understood that, as illustrated, the strain gauge 100 is arranged from left to right on the paper, and the middle trunk part of the strain gauge is in a long strip cylindrical structure, and the so-called center axis is also the axis of the trunk part of the strain gauge 100 (center axis), that is, the trunk part of the strain gauge 100 can be centrally symmetric with respect to the center axis.

[0039] Furthermore, in some embodiments, the strain gauge 100 may further include: a first reference arm 15, configured to extend from one vertical side of the stress relief hole 31 (as shown on the left side of the figure) toward and connect to the first fixing part 10, and the axis of the first reference arm 15 is configured to coincide with the axis of the elastic deformation part 30; a second reference arm 25, configured to extend from the other vertical side of the stress relief hole 31 (as shown on the right side of the figure) toward and connect to the second fixing part 20, and the axis of the second reference arm 25 is configured to coincide with the axis of the elastic deformation part 30. It should be understood that the aforementioned axis is generally considered to be the central axis of its main body. Ensuring the coincidence of the axes can be structurally guaranteed. In application, this allows the deformation of the elastic deformation part 30 to primarily change along the axial direction, thereby making the optical path in the optical cavity of the strain gauge more stable, resulting in a more uniform intensity distribution of the light beam, a more regular light spot shape, improved coupling efficiency, reduced optical signal loss, and improved white light interference efficiency and accuracy. Of course, to ensure deformation stability, the following embodiments also provide further optimization schemes.

[0040] Furthermore, in some embodiments, the axially symmetrical stress relief holes 31 are configured to be axially symmetrical with respect to the axis of the elastic deformation portion 30; the deformation stabilization retaining holes 32 are illustrated in two pairs, namely a first deformation stabilization retaining hole 32-1, a second deformation stabilization retaining hole 32-2, a third deformation stabilization retaining hole 32-3, and a fourth deformation stabilization retaining hole 32-4. The first deformation stabilization retaining hole 32-1 and the third deformation stabilization retaining hole 32-3 form one pair, while the second deformation stabilization retaining hole 32-2 and the fourth deformation stabilization retaining hole 32-4 form a second pair. The two deformation stabilization retaining holes in each pair are arranged axially symmetrical with respect to the axis of the elastic deformation portion. It should be understood that the paired deformation stabilization retaining holes can reduce the vertical deviation of the elastic deformation portion 30 along the plane of the paper during deformation.

[0041] Furthermore, in some embodiments, the elastic deformation portion 30 is constructed with an upper quadrilateral structure and a lower quadrilateral structure that are axially symmetrical about the axis of the elastic deformation portion, referring to... Figure 2 As shown, a line drawing is created by extracting the frame structure of the elastic deformation section 30. It should be understood that, in order to more clearly explain the principle-level relationship between the first deformation stabilizing retaining hole 32-1, the third deformation stabilizing retaining hole 32-3, the second deformation stabilizing retaining hole 32-2, and the fourth deformation stabilizing retaining hole 32-4, therefore... Figure 2 The ellipsis expresses Figure 1The stress relief hole 31 is shown in the diagram. The upper quadrilateral structure is constructed with a first lower horizontal edge 34 that is parallel to and close to the axis of the elastic deformation portion 30, and a first upper horizontal edge 33 that is opposite to and parallel to the first lower horizontal edge 34; the lower quadrilateral structure is constructed with a second upper horizontal edge 35 that is parallel to and close to the axis of the elastic deformation portion 30, and a second lower horizontal edge 36 that is opposite to and parallel to the second upper horizontal edge 35. Preferably, in some embodiments, the axis of the elastic deformation portion 30 is arranged to pass through the first lower horizontal edge 34 and the second upper horizontal edge 35, such that the first lower horizontal edge 34 and the second upper horizontal edge 35 coincide (shown as one edge in the illustrated frame structure).

[0042] Furthermore, in some embodiments, the deformation-stabilizing retaining hole is configured as a bone-like or I-shaped structure, such as... Figure 1 The structure shown is an I-shaped structure. When the elastic deformation part 30 undergoes elastic compression or tensile deformation along the axial direction, the deformation stabilization retaining hole 32 in the upper quadrilateral structure is located on the upper horizontal edge and the first upper horizontal edge (e.g., Figure 1 The uppermost horizontal edge of the elastic deformation section 30 remains parallel; the lower horizontal edge of the deformation stabilization retaining hole 32 provided in the lower quadrilateral structure is parallel to the second lower horizontal edge (e.g., Figure 1 The lowest horizontal edge of the elastic deformation section 30 remains parallel.

[0043] Furthermore, in some alternative embodiments, when another structural elastic deformation portion 130 is configured with a pair of deformation stabilization retaining holes 132, such as Figure 3 As shown and combined Figure 1 and Figure 2 The two deformation stabilizing holes 132 are arranged symmetrically with respect to the axis of the elastic deformation part; wherein, one of the two deformation stabilizing holes 132 is disposed in the upper quadrilateral structure, and the other deformation stabilizing hole 132 is disposed in the lower quadrilateral structure; the upper horizontal side of the deformation stabilizing hole 132 disposed in the upper quadrilateral structure is configured to be aligned with the first upper horizontal side (e.g., Figure 3 The uppermost horizontal edge of another structural elastic deformation section 130 is close to and parallel to the lower horizontal edge of the deformation stabilization retaining hole in the lower quadrilateral structure, and the lower horizontal edge is arranged to be close to the second lower horizontal edge (e.g., Figure 3 The bottom horizontal edge of the other structural elastic deformation part 130 is close to and parallel to it.

[0044] Furthermore, in some embodiments, when the elastic deformation portion is constructed with two pairs of deformation stabilization retaining holes, it still functions as before. Figure 1 As shown and combined Figure 2The first deformation stabilizing hole 32-1 and the second deformation stabilizing hole 32-2 of the four deformation stabilizing holes are disposed within the upper quadrilateral structure, and the third deformation stabilizing hole 32-3 and the fourth deformation stabilizing hole 32-4 of the four deformation stabilizing holes are disposed within the lower quadrilateral structure; the upper horizontal edge of the first deformation stabilizing hole 32-1 is positioned close to and parallel to the first upper horizontal edge, and the upper horizontal edge of the second deformation stabilizing hole 32-2 is positioned close to and parallel to the first upper horizontal edge. Furthermore, the first deformation stabilization retaining hole 32-1 and the second deformation stabilization retaining hole 32-2 are divided by the upper half of the stress relief hole 31 within the upper quadrilateral structure; the lower horizontal edge of the third deformation stabilization retaining hole 32-3 is set to be close to and parallel to the second lower horizontal edge, and the lower horizontal edge of the fourth deformation stabilization retaining hole 32-4 is set to be close to and parallel to the second lower horizontal edge, and the third deformation stabilization retaining hole 32-3 and the fourth deformation stabilization retaining hole 32-4 are divided by the lower half of the stress relief hole 31 within the upper quadrilateral structure.

[0045] Furthermore, in some embodiments, see Figure 1 and Figure 3 The stress relief hole 31 is constructed in a bone-like or I-shaped structure. The upper horizontal edge of the stress relief hole 31 is positioned close to and parallel to the first upper horizontal edge, and the lower horizontal edge of the stress relief hole 31 is positioned close to and parallel to the second lower horizontal edge. The longitudinal axis of the stress relief hole 31 (e.g., Figure 1 or Figure 3 As shown, the axis (shown as vertical on the paper) passes through and is perpendicular to the elastically deformed part. It should be understood that the stress relief hole 31 can be considered as a parallelogram structure with four weak nodes distributed in a bone-like pattern.

[0046] Furthermore, in some embodiments, in order to ensure the stability of the strain gauge in detecting axial stress and strain, when the elastic deformation part undergoes axial elastic compression deformation or tensile deformation, the upper horizontal edge of the stress relief hole remains parallel to the first upper horizontal edge, and the lower horizontal edge of the stress relief hole remains parallel to the second lower horizontal edge.

[0047] Furthermore, in some embodiments, in order to address such as Figure 1 or Figure 3The first fixed part is arranged as a first upper fixed part and a first lower fixed part. The fixed end surface of the first upper fixed part and the fixed end surface of the first lower fixed part are arranged separately, but need to be in the same plane. Thus, when the measured object is measured by the strain gauge, the first upper fixed part arranged as a separate welding plate is subjected to the paper vertical stress, and the first lower fixed part is not affected. If the first upper fixed part and the first lower fixed part are on the same welding plate, when the first upper fixed part is subjected to the paper vertical stress, the first lower fixed part will be inevitably affected and subjected to the paper vertical stress, thereby affecting the stable detection of the whole strain gauge and the accuracy of the final result. Similarly, the second fixed part is arranged as a second upper fixed part and a second lower fixed part. The fixed end surface of the second upper fixed part and the fixed end surface of the second lower fixed part are arranged separately but in the same plane.

[0048] Further, in some alternative embodiments, the strain gauge can be mainly provided with a core component white light interference module including a collimator and a reflection end surface. Figure 1 The first fixed part 10 and the second fixed part 20 are at the axial position of the strain gauge 100. The collimator can be fixed in the first reference arm 15. The end of the collimator is connected with the light source and the light path through the optical fiber. If the elastic deformation part 30 can be in stable axial strain in the elastic tensile deformation or the elastic compressive deformation, the collimator can convert the light emitted by the light source into parallel light beams, so that the intensity distribution of the light beams is more uniform, the spot shape is more regular, the coupling efficiency is improved, the loss of the optical signal is reduced, the white light interference efficiency and accuracy are improved. Correspondingly, the reflection end surface is fixed in the second reference arm 25. The white light interference is formed between the collimator and the reflection end surface. The reflection end surface has high flatness and surface roughness at the end facing the collimator, so as to ensure the accuracy and reliability of the optical interference measurement. The axial displacement between the first reference arm 15 and the second reference arm 25 is directly reflected on the collimator and the reflection end surface, causing the change of the optical interference cavity length. The demodulation of the cavity length change can calculate the distance change between the measurement arm and the reference arm, thereby completing the strain measurement of the surface of the measured object.

[0049] Further, in some embodiments, referring to Figure 1, the first fixed part 10 and the second fixed part 20 are connected to the measured object by spot welding, the spot welding structure is used to weld the strain gauge to the surface of the measured object, and the midpoint distance of the spot welding structure is the gauge length measured by the strain gauge. Further, taking the first fixed part 10 as an example, the spot welding structure on the left side of the drawing includes welding pieces distributed on the upper and lower sides of the first reference arm 15, and the spot welding structure on the right side of the drawing includes welding pieces distributed on the upper and lower sides of the second reference arm 25. Each welding piece includes 4 recessed spot welding positioning points, which ensure the accuracy and strength of the welding position. It should be understood that the number of welding points shown is only illustrative; in addition to the fixing function, it also ensures as much as possible the symmetry of the upper and lower sides, so as to facilitate the stable axial strain of the elastic deformation part 30 in the elastic tensile deformation or elastic compressive deformation. It should also be understood that the bottom surfaces of two adjacent welding pieces (for example, the welding pieces on the upper and lower sides of the first fixed part 10) are in the same plane, but the two planes are not connected, and a spacing part is arranged at the middle position, for example, the recess 11 shown in Figure 4 If the measured object surface is not flat enough, the structure with the recess 11 will be more beneficial to the position of the welding pieces on the measured object. In addition, the recess 11 also weakens the connection strength between the welding pieces and the first reference arm 15 or the second reference arm 25 to a certain extent. When the measured object surface has slight bending or twisting, the welding pieces and the main structure have low rigidity, and can absorb part of the deformation, so that the adverse deformation is not transferred to the elastic body, causing light interference failure.

[0050] Further, in some embodiments, referring to Figure 1 The elastic deformation part 30 is used to connect the first reference arm 15 and the second reference arm 25, and needs to transmit the deformation of the measured object surface and maintain the stability of the optical interference cavity between the first reference arm 15 and the second reference arm 25. Five holes are processed on the elastic deformation part 30, the middle rectangular hole (which has been shown as the stress release hole 31) is used for axial stress release and can absorb the displacement deformation between the first reference arm 15 and the second reference arm 25, and the remaining four holes (such as the first deformation stability maintaining hole 32-1, the second deformation stability maintaining hole 32-2, the third deformation stability maintaining hole 32-3, and the fourth deformation stability maintaining hole 32-4 shown in the drawing) are distributed on the two sides of the first reference arm 15 and the second reference arm 25. Four weak points 38 are processed inside the four holes (for example, taking the first deformation stability maintaining hole 32-1 in the shape of a capital I as an example, the center points at the left and right ends of the upper horizontal segment of the capital I, for example, referring to Figure 5), with the four weak points in the holes as the vertices, and a parallelogram structure is formed in each hole, which is used to maintain the stability of the interference cavity when the elastomer is compressed or stretched. In short, the parallelogram structure with the four weak nodes in the bone-shaped distribution, in which the four weak nodes are connected to form a parallelogram structure.

[0051] Further, in some embodiments, referring to Figure 1 , Figure 2 and Figure 5 , the parallelogram structure corresponding to the first and second strain-stable holding holes 32-1 and 32-2 shares a side, for example, the first upper horizontal side 33, and correspondingly, the third and fourth strain-stable holding holes 32-3 and 32-4 also share a side, for example, the second lower horizontal side 36. When the structure is processed, the first upper horizontal side 33 and the second lower horizontal side 36 need to be ensured in a parallel state. Obviously, the first upper horizontal side 33 and the second lower horizontal side 36 are also parallel to the first reference arm 15 and the second reference arm 25. During the deformation of the elastic deformation part 30 with the measured object, the first reference arm 15 and the second reference arm 25 approach or move away from each other, causing the first strain-stable holding hole 32-1, the second strain-stable holding hole 32-2, the third strain-stable holding hole 32-3, and the fourth strain-stable holding hole 32-4 to deform. Due to the special structure of the parallelogram, the first reference arm 15 and the second reference arm 25 will also remain parallel during the deformation process. Due to the parallel constraint of the first upper horizontal side 33 and the second lower horizontal side 36, the first reference arm 15 and the second reference arm 25 can only move in the respective axial direction, and other direction and angle deformations will be excluded by the first upper horizontal side 33 and the second lower horizontal side 36. In combination with the above-mentioned welded sheet recess structure (which can be a groove structure in some embodiments), the welded sheet structure absorbs the adverse deformation, thereby avoiding the spectral degradation of the strain gauge 100 caused by the adverse deformation, resulting in the failure of the sensing and measuring part therein.

[0052] It should be understood that, in some embodiments, referring to Figure 1 , the strain gauge 100 is a strain measurement device mounted on the surface of the measured object by spot welding. The connection of the strain gauge 100 with the measured object is usually through two places, which correspond to the first fixed part 10 and the second fixed part 20 of the strain gauge 100, which has a spot welding structure. By measuring the displacement of the two mounting positions, the strain of the strain gauge mounting position on the surface of the measured object can be obtained by dividing the distance between the two points.

[0053] It should also be understood that, in some embodiments, referring to Figure 1The first fixed part 10 and the second fixed part 20 are connected with the first reference arm 15 and the second reference arm 25 respectively by a spot welding structure, and fixing the first fixed part 10 and the second fixed part 20 on the surface of the measured object (through the spot welding structure) is equivalent to fixing the first reference arm 15 and the second reference arm 25 on the surface of the measured object. A white light interference cavity is constructed between the collimator in the first reference arm 15 and the reflection end block in the second reference arm 25. When the distance between the first reference arm 15 and the second reference arm 25 changes, the cavity length of the white light interference cavity changes synchronously. The distance change between the first reference arm 15 and the second reference arm 25 can be obtained by demodulating the cavity length, and then the strain of the surface of the measured object can be obtained. It should be understood that the white light interference principle has a very high requirement for the stability of the interference cavity. The first reference arm 15 and the second reference arm 25 need to move along the central axis, and displacement, bending or twisting in other directions will cause the interference cavity to fail, so ensuring the stability of the interference cavity is the key to the design of the sensor.

[0054] It should also be understood that in some embodiments, the example is still taken as Figure 1 and reference is made to Figure 2 and Figure 5The elastic deformation section 30 is integrally machined, which makes it easier to ensure structural accuracy. One side of the elastic deformation section 30 is the first reference arm 15, and the other side is the second reference arm 25. A stress relief hole 31, a first deformation stabilization holding hole 32-1, a second deformation stabilization holding hole 32-2, a third deformation stabilization holding hole 32-3, and a fourth deformation stabilization holding hole 32-4 are provided in the middle. The stress relief hole 31 in the middle is used to absorb the displacement between the first reference arm 15 and the second reference arm 25. The other four deformation stabilization holding holes are distributed on both sides of the first reference arm 15 and the second reference arm 25. The structures corresponding to the first deformation stabilization holding hole 32-1, the second deformation stabilization holding hole 32-2, the third deformation stabilization holding hole 32-3, and the fourth deformation stabilization holding hole 32-4 will absorb the strain. The first reference arm 15 and the second reference arm 25 are connected to the first upper horizontal edge 33 and the second lower horizontal edge 36. The first upper horizontal edge 33 and the second lower horizontal edge 36 are parallel to each other, and the first upper horizontal edge 33 and the second lower horizontal edge 36 are parallel to the first reference arm 15 and the second reference arm 25. Since the weak structures corresponding to the first deformation stabilization holding hole 32-1, the second deformation stabilization holding hole 32-2, the third deformation stabilization holding hole 32-3, and the fourth deformation stabilization holding hole 32-4 all form a parallelogram structure through the weak point 38, such a structure allows the first upper horizontal edge 33 and the second lower horizontal edge 36 to keep the first reference arm 15 and the second reference arm 25 moving along their respective axial directions during the deformation of the elastic deformation part 30, thereby ensuring the stability of the white light interference cavity. It should be understood that the primary function of the first deformation stabilization retaining hole 32-1, the second deformation stabilization retaining hole 32-2, the third deformation stabilization retaining hole 32-3, and the fourth deformation stabilization retaining hole 32-4 is to ensure that the axes remain concentric when the first reference arm 15 and the second reference arm 25 undergo relative displacement, thereby maintaining the stability of the interference cavity.

[0055] Furthermore, to further explain the stability issue of the elastically deformable part 30, see [link to relevant documentation]. Figure 6 As shown. In Figure 6 In the middle, it is aimed at Figure 1 The strain gauge 100 extracts its linear structure and places the elastic deformation section 30 in a schematic state of tensile deformation, as shown in the reference. Figure 2, the first deformation stable holding hole 32-1, the second deformation stable holding hole 32-2, the third deformation stable holding hole 32-3, and the fourth deformation stable holding hole 32-4 are four congruent rectangles before deformation, which is the design intention, and the machining needs to follow this design intention to ensure that the first deformation stable holding hole 32-1, the second deformation stable holding hole 32-2, the third deformation stable holding hole 32-3, and the fourth deformation stable holding hole 32-4 are congruent rectangles. When the distance between the first reference arm 15 and the second reference arm 25 changes, the first deformation stable holding hole 32-1, the second deformation stable holding hole 32-2, the third deformation stable holding hole 32-3, and the fourth deformation stable holding hole 32-4 will be deformed into parallelograms, as shown in Figure 6 It should be understood that the structural constraint needs to make the first upper horizontal edge 33 and the second lower horizontal edge 36 relatively parallel, and during machining, it is also necessary to try to ensure that the two edges keep the first upper horizontal edge 33 and the second lower horizontal edge 36 in a parallel position, which can be theoretically guaranteed. During the deformation process, the first deformation stable holding hole 32-1, the second deformation stable holding hole 32-2, the third deformation stable holding hole 32-3, and the fourth deformation stable holding hole 32-4 will gradually deform into parallelograms and can only deform into parallelograms because the four weak points 38 (see Figure 5As shown in the figure, that is, the four corner positions of the rectangle are determined after the processing is completed, that is, the four side lengths of the rectangle are fixed (the opposite sides are equal), so when stretched or compressed, it can only evolve into a parallelogram, and because of the existence of the first upper horizontal edge 33 and the second lower horizontal edge 36, the deformation degree of the first deformation stable retention hole 32-1, the second deformation stable retention hole 32-2, the third deformation stable retention hole 32-3, and the fourth deformation stable retention hole 32-4 is the same, only the deformation direction is different. From the structure, it can be understood as follows: assuming that the first reference arm 15 is fixed, when using external force to make the first deformation stable retention hole 32-1 (or the third deformation stable retention hole 32-3) deform, during the deformation process, the first upper horizontal edge 33 and the second lower horizontal edge 36 are always relatively parallel, so that the first upper horizontal edge 33 and the second lower horizontal edge 36 are relatively parallel to the first reference arm 15 (the opposite sides of the parallelogram), and the second reference arm 25 as the opposite side of the first reference arm 15 must also be relatively parallel to the first upper horizontal edge 33 and the second lower horizontal edge 36, so it can be known that the first reference arm 15 and the second reference arm 25 are relatively parallel during the deformation process, and the parallelogram contained in the first deformation stable retention hole 32-1, the second deformation stable retention hole 32-2, the third deformation stable retention hole 32-3, and the fourth deformation stable retention hole 32-4, all the vertical edges are marked as a, and the horizontal edges are considered as b, during the deformation process, the lengths of a and b are unchanged, such as Figure 6As shown, since the first deformation stability holding hole 32-1, the second deformation stability holding hole 32-2, the third deformation stability holding hole 32-3, and the fourth deformation stability holding hole 32-4 are parallelograms, the first reference arm 15 and the second reference arm 25 must also be collinear during deformation. Here, the first deformation stability holding hole 32-1, the second deformation stability holding hole 32-2, the third deformation stability holding hole 32-3, and the fourth deformation stability holding hole 32-4 are indispensable, and the absence of any one of them cannot guarantee that the first reference arm 15 and the second reference arm 25 are collinear during deformation. Further, the stress release hole 31 has two functions: one is to absorb the displacement between the first reference arm 15 and the second reference arm 25; the other is to separate the two vertical edges of the first deformation stability holding hole 32-1 and the second deformation stability holding hole 32-2, and the two vertical edges of the third deformation stability holding hole 32-3 and the fourth deformation stability holding hole 32-4, because during the deformation of the elastic deformation part 30, the deformation direction of the first deformation stability holding hole 32-1 and the second deformation stability holding hole 32-2 is opposite, and the deformation direction of the third deformation stability holding hole 32-3 and the fourth deformation stability holding hole 32-4 is opposite, so the vertical edges of the first deformation stability holding hole 32-1 and the second deformation stability holding hole 32-2 and the third deformation stability holding hole 32-3 and the fourth deformation stability holding hole 32-4 must be separated and cannot be shared. The vertical dimension of the stress release hole 31 needs to extend to the first upper horizontal edge 33 and the second lower horizontal edge 36. Further, the second function of the first deformation stability holding hole 32-1, the second deformation stability holding hole 32-2, the third deformation stability holding hole 32-3, and the fourth deformation stability holding hole 32-4 is to weaken the structural rigidity of the elastic deformation part 30, so that the elastic deformation part 30 can transmit strain. In theory, the longer the vertical edge length a of the first deformation stability holding hole 32-1, the second deformation stability holding hole 32-2, the third deformation stability holding hole 32-3, and the fourth deformation stability holding hole 32-4, the greater the displacement that the elastic deformation part 30 can absorb, and the greater the range of strain measurement of the strain gauge 100. This is because the deformation limit of each corner point in the first deformation stability holding hole 32-1, the second deformation stability holding hole 32-2, the third deformation stability holding hole 32-3, and the fourth deformation stability holding hole 32-4 is fixed under the same processing conditions, i.e., the amount of change in the angle between the vertical edge a and the horizontal edge b after deformation is fixed, and the longer the vertical edge a, the greater the relative displacement between the first reference arm 15 and the second reference arm 25. Similarly, the longer a is, the smaller the additional stress of the strain gauge 100 under the same measurement range (the same relative displacement of the first reference arm 15 and the second reference arm 25), i.e., the longer a is, the smaller the amount of deformation required for the first reference arm 15 and the second reference arm 25 to reach a fixed displacement value (i.e., the smaller the amount of change in the angle between a and b required).However, the larger the vertical dimension a, the less conducive to the stability of the structure, because the longer a is, the greater the distance between the first upper horizontal edge 33 and the second lower horizontal edge 36 and the first reference arm 15 (or the second reference arm 25), because the holding effect of the first upper horizontal edge 33 and the second lower horizontal edge 36 is embodied in the plane of the elastic deformation portion 30, in the thickness direction (perpendicular to the paper surface direction), the stability of the elastic deformation portion 30 needs to be completed by means of the thickness of the elastic deformation portion 30 itself, if the length of a in the first upper horizontal edge 33 and the second lower horizontal edge 36 is much greater than the thickness of the elastic deformation portion 30, the stability of the elastic deformation portion 30 will also be poor, so, from the point of view of maintaining the stability of the elastic deformation portion 30, the length of the first reference arm 15 and the second reference arm 25 itself, the length of the vertical edge a and the horizontal edge b of the first deformation stability holding hole 32-1, the second deformation stability holding hole 32-2, the third deformation stability holding hole 32-3, the fourth deformation stability holding hole 32-4, the thickness of the elastic deformation portion 30 should all be kept within a reasonable proportion range. Further, for the first reference arm 15 and the second reference arm 25 corresponding to the strain gauge 100, both are used to transfer strain to the deformation structure of the elastic deformation portion 30, and symmetric design should be adopted, and the lengths should be as equal as possible. Further, in some embodiments, the length of the horizontal edge b of the first deformation stability holding hole 32-1, the second deformation stability holding hole 32-2, the third deformation stability holding hole 32-3, the fourth deformation stability holding hole 32-4 is necessarily less than the length of the first reference arm 15 or the second reference arm 25, because the length of the first reference arm 15 (or the second reference arm 25) contains the length of the welding position and possibly the length of the protective cover in addition to b, but from the design intention, the longer the length of b is, the more conducive to the stability of the elastic deformation portion 30.Further, in some embodiments, the length of a is mainly determined by the range requirement of the strain gauge 100, for example, in some preferred embodiments, the gauge length of the strain gauge is 30mm, the range requirement of the strain gauge is ±2000 micro-strain, i.e. the relative displacement between the first reference arm 15 and the second reference arm 25 needs to reach 0.06mm, under such deformation requirement, the stress of the material also needs to be within a reasonable range (and considering a certain safety factor), the length of a is also related to the additional force of the sensor, for example, when the elastic deformation part 30 reaches the theoretical maximum deformation, an additional force of about 30N needs to be applied to the elastic deformation part 30, which needs to be borne by the welding points of the elastic deformation part 30, so the additional force of the elastic body puts requirements on the strength and number of the welding points, preferably, considering the quality and safety margin of the welding points, 6 spot welds are arranged on each welding piece (although some drawings show 4), the number of spot welds can be adjusted according to the welding quality and additional force requirement, but for the accuracy of the strain gauge 100, the fewer the welding points, the clearer the strain transfer gauge length, the more beneficial to the measurement accuracy of the strain gauge 100, so the spot welds should not be blindly increased, the additional force of the strain gauge 100 is related to the length of a, and also related to the strength of the weak points 38 in the first deformation stabilizing hole 32-1, the second deformation stabilizing hole 32-2, the third deformation stabilizing hole 32-3 and the fourth deformation stabilizing hole 32-4, the smaller the strength of the weak points 38, the smaller the additional force, but the strength of the weak points 38 also affects the stability of the sensor, the higher the strength of the weak points 38, the better the stability of the elastic body, so these values should be balanced in design, under the premise of meeting the additional force and range requirements, the value of a should be as small as possible, which can improve the stability of the elastic deformation part 30 and reduce the size of the strain gauge 100. Further, the thicker the thickness of the elastic deformation part 30, the better the stability of the elastic deformation part 30, the thinner the elastic deformation part 30, the more easily affected by bending, twisting and other deformations, but the thicker the elastic deformation part 30, the higher the overall height of the strain gauge 100, and the larger the additional force, so the thickness of the elastic deformation part 30 should also be within a reasonable range.

[0056] Further, in some embodiments, referring to Figures 1-6 The lower surface of the first fixed part 10 and the second fixed part 20 is processed with a groove structure (such as Figure 4The recess 11 is shown in the figure. The recess 11 can facilitate the installation of the strain gauge on the surface of the measured object. Due to the weakening of the structure by the recess 11, the first fixing part 10 and the second fixing part 20 with the spot welding structure can absorb a part of the deformation in other directions, bending or torsion in addition to the axial direction of the first reference arm 15 and the second reference arm 25. The principle is to adjust the strength of the weak structure in the first deformation stabilizing retaining hole 32-1, the second deformation stabilizing retaining hole 32-2, the third deformation stabilizing retaining hole 32-3, the fourth deformation stabilizing retaining hole 32-4 and the structural strength of the recess 11 of the first fixing part 10 or the second fixing part 20, so that the axial stiffness of the elastic deformation part 30 is low. When the surface of the measured object has axial displacement transmission, the elastic deformation part 30 will be preferentially absorbed, thereby achieving the purpose of strain measurement. The deformation caused by other directions or bending and torsion will be preferentially absorbed by the spot welding structure of the first fixing part 10 and the second fixing part 20, because the stiffness in other directions in addition to the axial direction is weaker at the spot welding structure of the first fixing part 10 and the second fixing part 20. By adjusting the stiffness of the recess 11 structure of the first fixing part 10 and the second fixing part 20, the strain gauge 100 as a whole can be balanced to ensure the accuracy and stability of the measurement. The purpose of the recess 11 is to weaken the connection strength between the welding sheet of the first fixing part 10 (or the second fixing part 20) and the first reference arm 15 (or the second reference arm 25). When the measured body has an unfavorable direction load (for example, which will cause the elastic body to bend or twist and affect the optical interference) transmitted to the strain gauge 100, the welding sheet of the strain gauge 100 will absorb most of the unfavorable deformation, so that the unfavorable deformation will not act on the elastic deformation part 30. However, the axial stiffness of the first reference arm 15 and the second reference arm 25 is smaller than the position where the welding sheet of the first reference arm 15 (or the second reference arm 25) is connected, and when the axial external force acts on the elastic deformation part 30, the load is mainly absorbed by the elastic deformation part 30, thereby performing strain measurement. It should also be understood that when subjected to bending moment, the deformation at the recess 11 is much larger than the deformation of the elastic body). Further, the strength design of the welding sheet of the first fixing part 10 and the second fixing part 20 here is related to the stiffness of the elastic deformation part 30. The limited welding sheet has a certain length in the axial direction, but its thickness is small, and the stiffness of the elastic deformation part 30 in the axial direction is small. The weak points of the first deformation stabilizing retaining hole 32-1, the second deformation stabilizing retaining hole 32-2, the third deformation stabilizing retaining hole 32-3, the fourth deformation stabilizing retaining hole 32-4 are weakened along the axial direction, so the axial stiffness of the elastic deformation part 30 is small. However, the thickness direction stiffness of the elastic deformation part 30 is the smallest at the welding sheet, so the axial load is absorbed by the elastic deformation part 30 for strain measurement, and the unfavorable load in other directions is absorbed by the welding sheet provided with the recess 11 for maintaining the stability of the optical interference.It should also be understood that when the strain gauge 100 is subjected to an axial load, the strain is mainly generated at the weak points (e.g., at the weak points 38) of the first deformation stabilizing hole 32-1, the second deformation stabilizing hole 32-2, the third deformation stabilizing hole 32-3, and the fourth deformation stabilizing hole 32-4, rather than at the dimples 11.

[0057] It should be understood that the core component of the strain gauge in the present disclosure is an optical interference cavity, which in some embodiments is arranged as follows: a collimating ferrule is fixed inside the first reference arm, and the collimating ferrule is arranged to fix the optical fiber collimator inside the ceramic ferrule, and the light emitting end face of the collimating ferrule is arranged to face the second reference arm; correspondingly, a reflecting ferrule is fixed inside the second reference arm, and the reflecting end face of the reflecting ferrule is arranged to face the first reference arm. Further, in order to ensure that the interference cavity works normally to achieve precision measurement, in some embodiments, the central axis of the collimating ferrule coincides with the central axis of the reflecting ferrule, and the central axis of the collimating ferrule and the central axis of the reflecting ferrule are perpendicular to the light emitting end face of the collimating ferrule and the reflecting end face of the reflecting ferrule. Further, in some embodiments, the light emitting end face of the collimating ferrule and the reflecting end face of the reflecting ferrule are close to each other, so that a white light interference cavity is formed between the light emitting end face of the collimating ferrule and the reflecting end face of the reflecting ferrule, the white light interference cavity is arranged to pass through the above-mentioned stress release hole, and the central axis of the white light interference cavity coincides with the axis of the above-mentioned elastic deformation part.

[0058] It should also be understood that in some additional embodiments, a MEMS fiber surface strain gauge is proposed for fixing on the surface of an object to be measured to measure the strain of the object under a corresponding load, having a left fixing part, a right fixing part, and a quadrilateral structure arranged between the left fixing part and the right fixing part, the quadrilateral structure being connected to the left fixing part and the right fixing part through diagonal connecting parts, a collimator arranged on a first side of the quadrilateral structure and a blazed grating arranged on a second side of the quadrilateral structure, the first side and the second side being two adjacent sides in the quadrilateral structure. The deformation of the quadrilateral structure is monitored by the change of the angle between the adjacent sides. In the additional embodiments described above, a parallelogram cavity (as an elastic strain structure) is used, which can be understood as a two-point fixing method, i.e. Figure 7The upper left one in the figure, i.e. fixed point 337 (at the lower left corner of the parallelogram cavity) and fixed point 339 (at the upper right corner of the parallelogram cavity), by stretching (after a slight displacement) the fixed point 337 and the fixed point 339, the angle between the horizontal long side aa and the vertical long side bb of the parallelogram cavity changes, and the displacement between the fixed point 337 and the fixed point 339 is measured by measuring the angle; however, in various embodiments of the present disclosure, the essence is to fix the fixed point 337 and the fixed point 338, when there is relative displacement between the two fixed points, the first reference arm and the second reference arm need to always keep coaxial relative operation to ensure stable demodulation of the optical interference cavity, and then the deformation stable holding hole constructed in the various embodiments of the present disclosure in the form of a bone-shaped structure or an I-shaped structure is to keep the first reference arm and the second reference arm coaxial during deformation. It should be understood that for different use scenarios, if the use scenario is angle measurement principle, it is direct angle measurement; the various embodiments of the present disclosure are based on white light interference distance measurement principle, which is direct distance measurement. Due to such differences, different structure construction methods are introduced; therefore, it cannot be considered that the parallelogram is a universal structure, and it is considered that the two have commonalities as long as the parallelogram is used.

[0059] The above has described various embodiments of the present disclosure, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles, practical applications, or technical improvements in the art, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

[0060] The above is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Those skilled in the art can make various modifications and changes to the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A strain gauge based on the principle of white light interference, arranged to be fixed on the surface of an object to be measured to measure the strain of the object under corresponding load, the strain gauge being arranged with a first fixed part, a second fixed part and an elastic deformation part arranged between the first fixed part and the second fixed part, the strain gauge being arranged to be fixedly connected with the object to be measured through the first fixed part and the second fixed part; characterized in that the elastic deformation part is arranged to be elastically compressed or stretched along the axial direction of the elastic deformation part; the elastic deformation part is configured to have an axially symmetric stress release hole and one or more pairs of axially symmetric deformation stabilizing holding holes for stabilizing the interference cavity strain of the strain gauge when the elastic deformation part is elastically compressed or stretched along the axial direction; the elastic deformation part is configured to have an upper quadrilateral structure and a lower quadrilateral structure which are axially symmetric relative to the axis of the elastic deformation part; the upper quadrilateral structure is configured to have a first lower horizontal side parallel to and close to the axis of the elastic deformation part, and a first upper horizontal side opposite to and parallel to the first lower horizontal side; the lower quadrilateral structure is configured to have a second upper horizontal side parallel to and close to the axis of the elastic deformation part, and a second lower horizontal side opposite to and parallel to the second upper horizontal side. Further comprising: a first reference arm configured to extend from one side vertical side of the stress release hole to the first fixed part and connected with the first fixed part, and the axis of the first reference arm is configured to coincide with the axis of the elastic deformation part; a second reference arm configured to extend from the other side vertical side of the stress release hole to the second fixed part and connected with the second fixed part, and the axis of the second reference arm is configured to coincide with the axis of the elastic deformation part.

2. The strain gauge according to claim 1, characterized in that 3. The strain gauge according to claim 1, characterized in that the axially symmetric stress release hole is configured to be axially symmetric relative to the axis of the elastic deformation part; the two deformation stabilizing holding holes in each pair of deformation stabilizing holding holes are arranged to be axially symmetric relative to the axis of the elastic deformation part.

4. The strain gauge according to claim 1, characterized in that the axis of the elastic deformation part is arranged to pass through the first lower horizontal side and the second upper horizontal side, so that the first lower horizontal side coincides with the second upper horizontal side.

5. The strain gauge according to claim 1, characterized in that the deformation stabilizing holding hole is configured to be a bone-like structure or an I-like structure, when the elastic deformation part is elastically compressed or stretched along the axial direction, the upper horizontal side of the deformation stabilizing holding hole arranged in the upper quadrilateral structure remains parallel to the first upper horizontal side; the lower horizontal side of the deformation stabilizing holding hole arranged in the lower quadrilateral structure remains parallel to the second lower horizontal side.

6. The strain gauge according to claim 5, characterized in that when the elastic deformation part is configured to have a pair of deformation stabilizing holding holes, the two deformation stabilizing holding holes are arranged to be axially symmetric relative to the axis of the elastic deformation part. ​ ​ ​ ​ ​ ​ ​ ​ One of the two deformation-stable holding holes is arranged in the upper quadrangular structure, and the other of the two deformation-stable holding holes is arranged in the lower quadrangular structure; the upper horizontal side of the deformation-stable holding hole arranged in the upper quadrangular structure is arranged close to and parallel with the first upper horizontal side, and the lower horizontal side of the deformation-stable holding hole arranged in the lower quadrangular structure is arranged close to and parallel with the second lower horizontal side.

7. The strain gauge according to claim 5, wherein, when the elastic deformation part is configured with two pairs of deformation-stable holding holes, the first and second deformation-stable holding holes of the four deformation-stable holding holes are arranged in the upper quadrangular structure, and the third and fourth deformation-stable holding holes of the four deformation-stable holding holes are arranged in the lower quadrangular structure; the upper horizontal side of the first deformation-stable holding hole is arranged close to and parallel with the first upper horizontal side, and the upper horizontal side of the second deformation-stable holding hole is arranged close to and parallel with the first upper horizontal side, and the first and second deformation-stable holding holes are divided by the upper half of the stress release hole in the upper quadrangular structure; the lower horizontal side of the third deformation-stable holding hole is arranged close to and parallel with the second lower horizontal side, and the lower horizontal side of the fourth deformation-stable holding hole is arranged close to and parallel with the second lower horizontal side, and the third and fourth deformation-stable holding holes are divided by the lower half of the stress release hole in the upper quadrangular structure.

8. The strain gauge according to claim 1, wherein, the stress release hole is configured in a bone-like structure or an I-like structure, the upper horizontal side of the stress release hole is arranged close to and parallel with the first upper horizontal side, and the lower horizontal side of the stress release hole is arranged close to and parallel with the second lower horizontal side; the longitudinal axis of the stress release hole passes through and is perpendicular to the axis of the elastic deformation part.

9. The strain gauge according to claim 6, wherein, when the elastic deformation part is elastically compressed or stretched in the axial direction, the upper horizontal side of the stress release hole remains parallel with the first upper horizontal side, and the lower horizontal side of the stress release hole remains parallel with the second lower horizontal side.

10. The strain gauge according to claim 1, wherein, the first fixed part is arranged as a first upper fixed part and a first lower fixed part, and the fixed end surface of the first upper fixed part and the fixed end surface of the first lower fixed part are arranged separately but in the same plane; the second fixed part is arranged as a second upper fixed part and a second lower fixed part, and the fixed end surface of the second upper fixed part and the fixed end surface of the second lower fixed part are arranged separately but in the same plane.

11. The strain gauge according to claim 2, wherein, The first reference arm is internally fixed with a collimating ferrule, which is arranged to fix the optical fiber collimator inside the ceramic ferrule, and the light emitting end face of the collimating ferrule is arranged to face the second reference arm; The second reference arm is internally fixed with a reflecting ferrule, and the reflecting end face of the reflecting ferrule is arranged to face the first reference arm.

12. The strain gauge according to claim 11, wherein The central axis of the collimating ferrule coincides with the central axis of the reflecting ferrule, and the central axis of the collimating ferrule and the central axis of the reflecting ferrule are perpendicular to the light emitting end face of the collimating ferrule and the reflecting end face of the reflecting ferrule.

13. The strain gauge according to claim 12, wherein The light emitting end face of the collimating ferrule and the reflecting end face of the reflecting ferrule are close to each other, so that a white light interference cavity is formed between the light emitting end face of the collimating ferrule and the reflecting end face of the reflecting ferrule, the white light interference cavity is arranged to pass through the stress release hole, and the central axis of the white light interference cavity coincides with the axis of the elastic deformation part.

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