Temperature self-compensating MEMS optical fiber strain sensor

Abstract

The utility model relates to a temperature self-compensating MEMS optical fiber strain sensor. The MEMS optical fiber strain sensor comprises a supporting base body which is constructed into a quadrilateral frame structure, wherein diagonal lines of the quadrilateral frame structure are perpendicular to one another, and four sides of the quadrilateral frame structure are equal in length; the first device comprises a first device free end and a first device restraining end, the first device restraining end is arranged to be fixed to one end of the long side of the quadrangular frame structure of the supporting base body, and the first device free end faces the direction close to the center of the supporting base body; the second device comprises a second device free end and a second device restraining end, and the second device restraining end is arranged to be fixed to the other end of the long side of the quadrilateral frame structure of the supporting base body; the free end of the second device faces the center direction away from the supporting base body. Some technical schemes of the utility model aim at improving the measurement precision and stability in a temperature change environment, and maintaining the difficulty of an original packaging process.

Description

Technical Field

[0001] The present application relates to the field of optical fiber sensing technology, and in particular to a temperature self-compensating MEMS optical fiber strain sensor. Background Art

[0002] Traditional MEMS fiber optic strain sensors will cause increased measurement errors when the ambient temperature changes, which seriously limits their reliability and accuracy in practical engineering applications. Specifically, as the external temperature changes, the sensor bracket and sensor sleeve will change accordingly with the temperature, which will cause the FP cavity in the MEMS fiber optic strain sensor to change, which will seriously affect the measurement results. This seriously limits the practical application of MEMS fiber optic strain sensors. Therefore, it is very necessary to perform temperature compensation on MEMS fiber optic strain sensors.

[0003] The existing technology involves strain sensors with low sensitivity, and the interference of temperature, structural deformation and other small creeps has a great impact on the measurement results. Existing related solutions also often rely on external temperature compensation devices or complex data processing algorithms, which increases the cost and complexity of the system.

[0004] Therefore, the prior art still needs to be improved and enhanced. Utility Model Content

[0005] In order to solve one or more of the above-mentioned technical problems, such as the problem that the existing MEMS optical fiber strain sensor is greatly affected by temperature interference and the measurement results are greatly affected, the present disclosure provides a temperature self-compensating MEMS optical fiber strain sensor, which aims to achieve accurate strain measurement in a wide temperature range through a built-in temperature self-compensation structure, thereby reducing the impact of ambient temperature changes on sensor performance and improving its reliability and stability in practical applications.

[0006] In a first aspect of the present disclosure, a temperature self-compensating MEMS optical fiber strain sensor is proposed, the MEMS optical fiber strain sensor comprising: a supporting substrate, which is constructed into a quadrilateral frame structure with mutually perpendicular diagonals and four sides of equal length; a first device, comprising a first device free end and a first device restraining end, the first device restraining end being arranged to be fixed on one end of a long side of the quadrilateral frame structure of the supporting substrate, and the first device free end facing a direction close to the center of the supporting substrate; a second device, comprising a second device free end and a second device restraining end, the second device restraining end being arranged to be fixed on the other end of the long side of the quadrilateral frame structure of the supporting substrate, and the second device free end facing a direction away from the center of the supporting substrate; wherein the supporting substrate and the second device are constructed to be composed of a first metal material with a consistent linear thermal expansion coefficient, and the first device is constructed to be composed of a second metal material with a linear thermal expansion coefficient higher than that of the first metal material. The first device includes a first collimating lens covered by a first metal tube, the first metal tube is made of the first metal material; the second device includes a second collimating lens covered by a second metal tube, the second metal tube is made of the second metal material. Further, in some embodiments, the first device and the second device are configured as a long strip structure with two ends.

[0007] Further, in some embodiments, the first device is configured to be in close contact with the supporting substrate, the first device constraint end is provided with a first device constraint end face at the end away from the free end of the first device, and the first device constraint end is configured to be fixed on one end of the long side of the quadrilateral frame structure of the supporting substrate at the edge close to the first device constraint end face and in contact with the supporting substrate; the second device is configured to be in close contact with the supporting substrate, the second device constraint end is provided with a second device constraint end face at the end away from the free end of the second device, and the second device constraint end is configured to be fixed on the other end of the long side of the quadrilateral frame structure of the supporting substrate at the edge close to the second device constraint end face and in contact with the supporting substrate.

[0008] Further, in some embodiments, the end face of the first device constraint end is set to the end face of the working end of the first collimating lens, and the end face of the second device constraint end is set to the end face of the working end of the second collimating lens; the end face of the working end of the first collimating lens is set to face the end face of the working end of the second collimating lens; and the end face of the working end of the first collimating lens is set to be parallel and coaxial with the end face of the working end of the second collimating lens.

[0009] Further, in some embodiments, the first metal tube includes a first metal tube free end and a first metal tube constraint end, the first device free end is configured as the first metal tube free end and close to the working end of the first collimating lens, and the first device constraint end is configured as the first metal tube constraint end and away from the working end of the first collimating lens; the second metal tube includes a second metal tube free end and a second metal tube constraint end, the second device constraint end is configured as the second metal tube constraint end and close to the working end of the second collimating lens, and the second device free end is configured as the second metal tube free end and away from the working end of the second collimating lens.

[0010] Further, in some embodiments, the distance from the first metal tube constraint end to the second metal tube constraint end is set to a length D1, and the distance from the first metal tube free end to the first metal constraint end is set to a length D2; so that when the linear thermal expansion coefficient of the first metal material is A1 and the linear thermal expansion coefficient of the second metal material is A2, D1*A1-D2*A2=0 is satisfied.

[0011] Furthermore, in some embodiments, the first device restraining end and the second device restraining end are respectively welded and fixed on the supporting substrate.

[0012] Furthermore, in some embodiments, the first metal material is composed of 4J36, and the second metal material is composed of nickel with a purity of 99%.

[0013] Furthermore, in some embodiments, the end surface of the working end of the above-mentioned first collimating lens is coated with a high-reflection film after being ground, and the reflectivity of the above-mentioned high-reflection film is set to 65%; the end surface of the working end of the above-mentioned second collimating lens is coated with a high-reflection film after being ground, and the reflectivity of the above-mentioned high-reflection film is set to 95%.

[0014] Further, in some embodiments, a dust cover is provided between the first component and the second component, and the dust cover is configured to cover and seal the gap between the first component and the second component.

[0015] Further, in some embodiments, the support substrate is configured as a rhombus structure, and the acute angle of the rhombus structure is set to 48°.

[0016] The beneficial effects of the present disclosure are:

[0017] 1) In some embodiments, accurate strain measurement within a wide temperature range is achieved through a built-in temperature self-compensation structure, thereby reducing the impact of ambient temperature changes on sensor performance and improving its reliability and stability in practical applications. Specifically, by metallizing the MEMS collimating lens, for example, a first collimating lens wrapped by a first metal tube and a second collimating lens wrapped by a second metal tube, the optical fiber and the metal material can be firmly welded together, and different metal materials are used to adjust their linear thermal expansion coefficients. After forming a corresponding structure, the self-temperature compensation of the MEMS optical strain sensor is achieved, which effectively reduces the impact of ambient temperature changes on the sensor measurement results, thereby significantly improving the measurement accuracy.

[0018] 2) In some embodiments, the first device constraint end is arranged to be welded and fixed on one end of the long side of the quadrilateral frame structure of the supporting substrate at the edge close to the end face of the first device constraint end and in contact with the supporting substrate, and the second device constraint end is arranged to be welded and fixed on the other end of the long side of the quadrilateral frame structure of the supporting substrate at the edge close to the end face of the second device constraint end and in contact with the supporting substrate, so as to prevent the mutual influence of expansion or contraction when the thermal expansion coefficients of the first device (or the second device) and the supporting substrate are different, thereby preventing the inability to determine the clear relationship between the expansion or contraction change of the device and the thermal expansion coefficient, thereby preventing the inability to determine the acquisition of key parameters of the self-temperature compensation device; then, the constraint end and the free end of the metal tube covering the collimating lens can be effectively set to effectively realize the positional relationship between the metal tube of the collimating lens, the supporting substrate, and the corresponding end faces of the metal tube, and realize the possibility of self-temperature compensation adjustment of the FP cavity therein (that is, the distance between the FP cavities does not change with temperature), thereby realizing the construction of self-temperature compensation of the MEMS optical strain sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings, in which:

[0020] Figure 1 A schematic diagram of a temperature self-compensating MEMS optical fiber strain sensor according to an embodiment of the present disclosure is shown;

[0021] Figure 2 A schematic diagram of a first device according to an embodiment of the present disclosure is shown;

[0022] Figure 3 A schematic diagram showing a second device according to an embodiment of the present disclosure is shown;

[0023] Figure 4 A schematic top view of a temperature self-compensating MEMS optical fiber strain sensor according to an embodiment of the present disclosure is shown;

[0024] Figure 5 A bottom view schematically shows a temperature self-compensating MEMS optical fiber strain sensor according to an embodiment of the present disclosure;

[0025] Figure 6 A schematic diagram showing the positional relationship of a temperature self-compensating MEMS optical fiber strain sensor according to an embodiment of the present disclosure; and

[0026] In each of the accompanying drawings, the same or corresponding reference numerals represent the same or corresponding parts; the reference numerals are: temperature self-compensating MEMS optical fiber strain sensors 100, 200, a first device 10, a first collimating lens 11, a first metal tube 12, a second device 20, a second collimating lens 21, a second metal tube 22, a supporting base 30, a dust cover 40, and a welding hole 50. DETAILED DESCRIPTION

[0027] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are only for exemplary purposes and are not intended to limit the scope of protection of the present disclosure.

[0028] In the description of the embodiments of the present disclosure, the term "including" and similar terms should be understood as open inclusion, 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. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0029] As described above, with the change of external temperature, the existing MEMS fiber optic strain sensor's bracket and sensor sleeve will change accordingly, which will cause the FP cavity in the MEMS fiber optic strain sensor to change, and then seriously affect the measurement results. This seriously limits the practical application of MEMS fiber optic strain sensors. Therefore, it is very necessary to perform temperature compensation on the MEMS fiber optic strain sensor.

[0030] In order to solve at least one of the above problems and one or more of other potential problems, an exemplary embodiment of the present disclosure proposes a temperature self-compensating MEMS optical fiber strain sensor, which includes a supporting substrate, a first device and a second device.

[0031] The following is a further explanation with reference to the accompanying drawings and embodiments.

[0032] Figure 1A schematic diagram of a temperature self-compensating MEMS optical fiber strain sensor according to an embodiment of the present disclosure is shown. In the illustrated embodiment, the temperature self-compensating MEMS optical fiber strain sensor 100 includes: a first device 10, a second device 20 and a supporting substrate 30; wherein the supporting substrate 30 is constructed as a quadrilateral frame structure (for example, a rhombus-like frame structure) with diagonals perpendicular to each other and four sides of equal length; the first device 10 is constructed with a long strip structure, which includes a first device free end and a first device constrained end. It should be understood that the so-called first device constrained end (the constrained end, i.e., the left end of the paper) is arranged to be fixed on one end of the long side of the quadrilateral frame structure of the supporting substrate 30 (the so-called long side refers to the horizontal long side and the vertical long side that the rhombus-like frame structure must have as shown in the figure, and the vertical long side). Straight short side), the free end of the first device faces the center direction close to the support base 30 (i.e. the right end of the paper); it should be understood that the first device constraint end is welded to the support base 30, and the leftmost end of the first device constraint end is aligned and fixed with the leftmost end of the support base 30; further, the second device 20 is also constructed with a similar long strip structure, which also includes a second device free end and a second device constraint end, and the corresponding second device constraint end (the constrained end, i.e. the left end of the paper) is arranged to be fixed on the other end of the long side of the quadrilateral frame structure of the support base 30; and the second device free end faces away from the center direction of the support base 30 (i.e. the right end of the paper). It should be understood that the above arrangement makes the end face of the constraint end of the first device flush with the end face of one end of the long side of the quadrilateral frame structure of the support base 30, which is used as the starting position (starting end face position) of the measurement. Further, if the first device expands due to heat, since its restraining end is limited (welded and fixed), it should be understood that the extension direction of its expansion will extend as far as possible toward its free end. In addition, it should also be understood that in some embodiments, the first device restraining end and the second device restraining end are respectively welded and fixed on the support base 30, thereby achieving their restraining effect.It should also be understood that the above-mentioned restraining end is limited (welded and fixed). Specifically, in some embodiments, the first device restraining end may be provided with a first device restraining end end face at the end away from the free end of the first device, and the first device restraining end is arranged to be welded and fixed to one end of the long side of the quadrilateral frame structure of the supporting substrate at the edge close to the first device restraining end face and in contact with the supporting substrate, while the free end of the first device faces the center direction close to the above-mentioned supporting substrate; accordingly, the second device is arranged to be close to the supporting substrate, and the second device restraining end is provided with a second device restraining end end face at the end away from the free end of the second device, and the second device restraining end is arranged to be welded and fixed to the other end of the long side of the quadrilateral frame structure of the supporting substrate at the edge close to the second device restraining end face and in contact with the supporting substrate; the free end of the second device faces the center direction away from the above-mentioned supporting substrate; further, the end face of the first device restraining end and the second device The end faces of the constraint ends are on the same side of the supporting substrate, and the end faces of the first device constraint ends and the second device constraint ends need to be constructed into a centrally symmetrical structure for easy alignment, and then the end face of the first device constraint end is arranged to be parallel to the end face of the second device constraint end and coaxial with the central axes of the two planes; it should be noted that the first device constraint end is arranged to be welded and fixed to the supporting substrate at the edge close to the end face of the first device constraint end and in contact with the supporting substrate (and the second device constraint end is arranged to be welded and fixed to the other end of the long side of the quadrilateral frame structure of the supporting substrate at the edge close to the end face of the second device constraint end and in contact with the supporting substrate), which can prevent the expansion or contraction of the first device (or the second device) and the supporting substrate from interacting with each other during thermal expansion and contraction when the thermal expansion coefficients are different, and then prevent the inability to determine the clear relationship between the expansion or contraction change of the device and the thermal expansion coefficient, thereby preventing the inability to determine the acquisition of key parameters of the self-temperature compensation device.

[0033] Furthermore, in order to explain the first device in more detail, a description is given below with reference to the accompanying drawings.

[0034] Figure 2 1 shows a schematic diagram of a first device according to an embodiment of the present disclosure. In the illustrated embodiment, the first device 10 includes a first collimating lens 11 covered by a first metal tube 12, and the first metal tube 12 is made of a first metal material. Figure 2 As shown, the rightmost end of the first collimating lens 11 in the first device 10 is its working end, and the end surface of its working end is the rightmost end surface of the paper. Figure 3 FIG. 2 shows a schematic diagram of a second device according to an embodiment of the present disclosure. In the illustrated embodiment, the second device 20 includes a second collimating lens 21 covered by a second metal tube 22, and the first metal tube 22 is made of a second metal material. Figure 3As shown in FIG. 1 , the leftmost end of the second collimating lens 21 in the second device 20 is its working end, and the end surface of its working end is the leftmost end surface of the paper. Figure 1-3 The end face of the working end of the first collimating lens 11 is arranged to be parallel and coaxial with the end face of the working end of the second collimating lens 21, so that an important part of the sensor, the FP cavity, can be formed between the two end faces. Figure 1-3 , the first metal tube 12 includes a first metal tube free end (the right end of the paper) and a first metal tube constraint end (the left end of the paper), the first device free end is configured as the first metal tube free end and is close to the working end of the first collimating lens 11 (the right end of the paper), and the first device constraint end is configured as the first metal tube constraint end and is away from the working end of the first collimating lens 11 (the left end of the paper); correspondingly, the second metal tube 22 includes a second metal tube free end (the right end of the paper) and a second metal tube constraint end (the left end of the paper), the second device constraint end is configured as the second metal tube constraint end and is close to the working end of the second collimating lens 21, and the second device free end is configured as the second metal tube free end and is away from the working end of the second collimating lens 21. It should be understood that the above-mentioned constraint end is generally configured to be welded and fixed to the supporting substrate at the end face of the working end and at the edge in contact with the supporting substrate. It should be noted that, as Figure 2-3 As shown, in some embodiments, the first device 10 and the second device 20 are configured as a long strip structure including two ends.

[0035] In addition, as a further solution, it will be explained below in conjunction with the accompanying drawings.

[0036] Figure 4 FIG. 2 is a top view of a temperature self-compensating MEMS optical fiber strain sensor according to an embodiment of the present disclosure. In this exemplary embodiment, the temperature self-compensating MEMS optical fiber strain sensor 200 further includes a dust cover 40, which is configured to cover and seal the gap area between the first device 10 and the second device 20. Figure 1-3It can be understood that the dust cover 40 starts from the free end (right end on the paper) of the first device 10 (first metal tube 12) and ends at the constrained end (left end on the paper) of the second device 20 (second metal tube 22), and the first collimating lens 11 extending from the first metal tube 12, the second collimating lens 21 extending from the second metal tube 22, and the FP cavity formed by the end face of the working end of the first collimating lens 11 and the end face of the working end of the second collimating lens 21 are all covered inside the dust cover 40, and the internal sealing thereof is achieved. In the illustrated embodiment, the supporting base 30 in a supporting role is constructed into a diamond-like frame structure, and its long side portions (i.e., the left and right ends of the paper) are respectively provided with the first device 10 and the second device 20. In particular, the leftmost end (the constrained end) of the first metal tube of the first device 10 is aligned and overlapped with the leftmost end of the supporting base 30, and the rightmost end (the free end) of the second metal tube of the second device 20 is aligned and overlapped with the rightmost end of the supporting base 30 (the right end overlaps only for the convenience of installation and assembly, and does not constrain the second metal tube from expanding to the left. The following embodiments will also explain that even if it expands, the free end will not be less than or more than the expansion degree of the supporting base 30). Furthermore, the temperature self-compensating MEMS optical fiber strain sensor 200 also includes a welding hole 50, which is an opening (welding hole 50) constructed by extending the short side of the supporting substrate 30 outward (inward toward the center of the supporting substrate 30, outward away from the center of the supporting substrate 30) for facilitating auxiliary fixation or enhanced fixation. The upper and lower ends are respectively constructed with one or more holes to fix the entire supporting substrate 30 on an external device (such as an external base or other matching base).

[0037] In addition, to further demonstrate, Figure 5 A schematic bottom view of a temperature self-compensating MEMS optical fiber strain sensor according to an embodiment of the present disclosure is shown. In the diagram, the first device 10 and the second device 20 are only arranged on one side of the support substrate 30, and it can also be seen that the left end of the first device 10 and the right end of the second device 20 do not exceed the left end and the right end of the support substrate 30. More obviously, the support substrate 30 is configured as a rhombus structure, and preferably, the acute angle of the rhombus structure (i.e., the long side corresponding to the arrangement of the first device 10 and the second device 20) is set to 48°.

[0038] Furthermore, in order to explain the temperature self-compensating MEMS optical fiber strain sensor from the perspective of structural principle, the specific structural relationship and the principles involved are described below in conjunction with the accompanying drawings.

[0039] Figure 6The schematic diagram of the positional relationship of the temperature self-compensating MEMS optical fiber strain sensor according to the embodiment of the present disclosure is shown. In this exemplary embodiment, the distance from the first metal tube constraint end to the second metal tube constraint end is set to a length D1 (or understood as the distance between the end face of the left end of the first metal tube and the end face of the left end of the second metal tube), and the distance from the free end of the first metal tube to the first metal constraint end is set to a length D2 (or understood as the distance between the end face of the left end of the entire first metal tube and the end face of the right end). Obviously, in the figure, the distance from the free end of the first metal tube to the second metal constraint end is set to a length D3, and has a relationship D1-D2=D3; in addition, the support substrate 30 and the second device 20 are constructed by a first metal having a linear thermal expansion coefficient A1 that is consistent with the first metal tube. The first device 10 is constructed to be composed of a second metal material whose linear thermal expansion coefficient A2 is higher than that of the first metal material; thereby, when the linear thermal expansion coefficient A1 of the first metal material and the linear thermal expansion coefficient A2 of the second metal material, and satisfying D1*A1-D2*A2=0, then, even if the D1 section of the supporting substrate 30 undergoes thermal expansion, the D2 section of the first device 10 also expands at the same time, and after the two expand, since the relationship D1*A1-D2*A2=0 is satisfied, D3 remains unchanged, thereby ensuring that the cavity length of the FP cavity does not change, thereby realizing temperature self-compensation of the MEMS optical fiber strain sensor.

[0040] Further, in some preferred embodiments, the first metal material is composed of 4J36, and the second metal material is composed of nickel with a purity of 99%.

[0041] Furthermore, in some preferred embodiments, the working end face of the first device (i.e., its quasi-diameter alignment end face) is ground and then coated with a high-reflection film, and the reflectivity of the high-reflection film is set to 65%; correspondingly, the working end face of the second device (i.e., its quasi-diameter alignment end face) is ground and then coated with a high-reflection film, and the reflectivity of the corresponding high-reflection film is set to 95%.

[0042] In summary, some of the above embodiments have the following beneficial effects: 1) Improve measurement accuracy: By metallizing the MEMS collimating lens, for example, the first collimating lens wrapped by the first metal tube and the second collimating lens wrapped by the second metal tube, the optical fiber and the metal material can be firmly welded together, and different metal materials are used to adjust their temperature coefficients to achieve self-temperature compensation of the MEMS optical strain sensor, effectively reducing the impact of ambient temperature changes on the sensor measurement results, thereby significantly improving the measurement accuracy. 2) Reduce system cost: Compared with the traditional method, some embodiments of the present disclosure adopt a simpler design, which does not require a complex external compensation device. It is achieved by adjusting the metal tube material and length of the MEMS collimating lens, simplifying the packaging process and reducing production costs. 3) Simplify the packaging process: After the MEMS collimating lens is metallized, it is connected to different metal tube materials through gold-tin solder; therefore, the optical fiber and the metal material strain gauge structure can be fixed and connected through a variety of welding methods such as laser welding, gold-tin soldering, and glass solder welding, enriching the diversity of the process and simplifying the packaging process. 4) Enhanced application flexibility: Temperature self-compensation technology makes the sensor more reliable in a wide range of strain measurement applications, including structural health monitoring, industrial production process control and other fields.

[0043] The following attempts to further illustrate some embodiments of the present disclosure.

[0044] In some embodiments, a temperature self-compensating MEMS optical fiber strain sensor is provided, which includes: a supporting substrate (for example, a rhombus-shaped substrate), a first device, a second device, and a dust cover. The first device includes a first collimating lens, a gold-plated nickel tube covering the outer surface of the first collimating lens; and the second device includes a second collimating lens, a gold-plated kovar tube covering the outer surface of the second collimating lens; further, the gold-plated nickel tube of the first collimating lens is fixed by gold-tin solder welding; the gold-plated kovar tube of the second collimating lens is fixed by gold-tin solder welding; the first device and the second device are aligned and fixed by laser welding or gold-tin solder welding or glass solder welding, and the first device and the second device are sealed and waterproof by a dust cover; the dust cover can be made of non-metallic material or metal film, with low rigidity, and does not affect the change of the cavity length of the FP cavity. Furthermore, in some embodiments, the supporting substrate (for example, a rhombus-shaped substrate) is a hollow structure with central symmetry and four sides of equal thickness. Preferably, the acute angle is designed to be 48°, and the sensitivity of the sensor can be adjusted by adjusting the angle of the supporting substrate; and the first device and the second device are respectively welded at the endpoints of the long diagonal of the rhombus substrate.

[0045] Furthermore, in order to satisfy the interference principle of the FP cavity, for the first device, the end face of the optical fiber is polished and coated with a high-reflection film, so that its reflectivity can reach about 65%; for the second device, the end face of the optical fiber is polished and coated with a high-reflection film, so that its reflectivity can reach more than 95%; when the light emitted by the light source enters the optical fiber, the light will reflect back and forth in the cavity between the collimating lenses of the first device and the second device, resulting in interference. The superposition of these reflected lights will form interference fringes, and their intensity and phase depend on the distance between the collimating lenses corresponding to the first device and the second device and the wavelength of the incident light. After the first device and the second device are welded to the supporting substrate, the supporting substrate is deformed by force (especially when it is a diamond structure), which drives the distance between the collimating lenses corresponding to the first device and the second device to change. By demodulating its interference spectrum, it can be obtained that the wavelength changes accordingly, thereby realizing the measurement of stress and strain.

[0046] Furthermore, with respect to the sensitivity design of the sensor: for example, it can be achieved by adjusting the distance between two mounting points of the rhombus substrate, ie, the gauge length; correspondingly, the sensitivity of the sensor can be adjusted by adjusting the angle of the rhombus substrate.

[0047] Furthermore, the positional relationship between the relevant components is explained from the installation perspective, and the installation of the support base is as follows: there is a glue groove on the bottom of the installation part, about 0.2mm, which can be used to fix the connection with glue while effectively controlling the thickness of the glue layer; further, a circular welding hole is left on the installation part, and the welding hole thickness is 0.4~0.5mm, which can be spot welded by a welding machine, so that it can be firmly fixed to the metal part being measured.

[0048] Furthermore, the realization of self-temperature compensation is explained by the following embodiments. For example, the support substrate is processed by 4J36, and its linear thermal expansion coefficient is about 1.2~2*10-6 / ℃; the material of the gold-plated nickel tube corresponding to the first device is nickel with a purity of 99%, and the linear thermal expansion coefficient is 12~13*10-6 / ℃; the gold-plated Kovar tube corresponding to the second device is made of 4J36 (the same material as the support substrate, that is, the linear thermal expansion coefficient is also the same); when the temperature rises, the free end of the first device extends into the support substrate structure (that is, toward the center of the support substrate), achieving the effect of temperature compensation.

[0049] For example, D1=D2+D3; when the temperature changes by ΔT: D1T=D1+ΔD1; D2T=D2+ΔD2, where ΔD1=ΔT*A1*D1; and ΔD2=ΔT*A2*D2; so there is a relationship D3T=(D1+ΔT*A1*D1)-(D2+ΔT*A2*D2)=(D1-D2)+ΔT*(A1*D1-A2*D2), where A1 is the linear expansion coefficient of the supporting substrate, and A2 is the linear thermal expansion coefficient of the pure nickel (gold-plated nickel tube) of the first device. Under the condition of temperature change, D3T=D3=D1-D2 can be achieved as long as A1*D1-A2*D2=0.

[0050] The various embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Without departing from the scope and spirit of the various embodiments described, many modifications and changes are obvious to those of ordinary skill in the art. The selection of terms used in this article is intended to best explain the principles of the various embodiments, practical applications, or technical improvements in the market, or to enable other ordinary technicians in this technical field to understand the various embodiments disclosed herein. It should also be understood that since the first collimating lens and the second collimating lens forming the FP cavity are not connected, when the supporting substrate of the diamond structure is deformed by pressure expansion and contraction, the FP cavity is deformed, but this force only acts on the surface of the structure, and there is no force between the first collimating lens and the second collimating lens, so the FP cavity is more stable and not easy to fatigue. In addition, since the optical fiber itself is relatively flexible and easy to bend, the first collimating lens and the second collimating lens are metallized. For example, the first collimating lens is covered by a first metal tube and the second collimating lens is covered by a second metal tube. For example, the first metal tube and the second metal tube can be gold-plated nickel tubes, so that the welded parts are metal, ensuring that the FP cavity formed between the first collimating lens and the second collimating lens at both ends is coaxial and collimated. It should also be understood that the end face of the working end of the above-mentioned first collimating lens is arranged to be parallel and coaxial with the end face of the working end of the above-mentioned second collimating lens, wherein the parallelism between the two end faces refers to the formation of a parallel relationship between two geometric planes, and the end face of the working end of the first collimating lens is arranged to be coaxial with the end face of the working end of the second collimating lens means that the cross-section of the "end face of the working end of the first collimating lens" is a centrally symmetrical geometric structure, such as a circle, then the axis passing through the center of the circular plane is the axis of the "end face of the working end of the first collimating lens", and then when the central axis of the "end face of the working end of the first collimating lens" coincides with the central axis of the "end face of the working end of the second collimating lens", the end face of the working end of the so-called first collimating lens is arranged to be coaxial with the end face of the working end of the second collimating lens.

[0051] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A temperature self-compensating MEMS optical fiber strain sensor, It is characterized in that include: The supporting base is constructed into a quadrilateral frame structure with diagonals perpendicular to each other and four sides of equal length; A first device, comprising a first device free end and a first device restraining end, wherein the first device restraining end is configured to be fixed on one end of a long side of a quadrilateral frame structure of the support substrate, and the first device free end faces toward a center direction close to the support substrate; A second device, comprising a second device free end and a second device restraining end, wherein the second device restraining end is configured to be fixed on the other end of the long side of the quadrilateral frame structure of the support substrate, and the second device free end faces away from the center direction of the support substrate; The supporting base and the second device are constructed to be composed of a first metal material with a consistent linear thermal expansion coefficient, and the first device is constructed to be composed of a second metal material with a higher linear thermal expansion coefficient than the first metal material; the first device includes a first collimating lens covered by a first metal tube, and the first metal tube is composed of the first metal material; the second device includes a second collimating lens covered by a second metal tube, and the second metal tube is composed of the second metal material.

2. The MEMS optical fiber strain sensor according to claim 1, It is characterized in that The first device is arranged to be in close contact with the supporting base, and the first device constraint end is provided with a first device constraint end end face at the end away from the free end of the first device, and the first device constraint end is arranged to be fixed on one end of the long side of the quadrilateral frame structure of the supporting base at the edge close to the first device constraint end face and in contact with the supporting base; the second device is arranged to be in close contact with the supporting base, and the second device constraint end is provided with a second device constraint end end face at the end away from the free end of the second device, and the second device constraint end is arranged to be fixed on the other end of the long side of the quadrilateral frame structure of the supporting base at the edge close to the second device constraint end face and in contact with the supporting base.

3. The MEMS optical fiber strain sensor according to claim 2, It is characterized in that The end face of the first device constraint end is arranged to be the end face of the working end of the first collimating lens, and the end face of the second device constraint end is arranged to be the end face of the working end of the second collimating lens; the end face of the working end of the first collimating lens is arranged to face the end face of the working end of the second collimating lens; and the end face of the working end of the first collimating lens is arranged to be parallel and coaxial with the end face of the working end of the second collimating lens.

4. The MEMS optical fiber strain sensor according to claim 3, It is characterized in that The first metal tube comprises a first metal tube free end and a first metal tube restraining end, the first device free end is arranged as the first metal tube free end and close to the working end of the first collimating lens, and the first device restraining end is arranged as the first metal tube restraining end and far away from the working end of the first collimating lens; The second metal tube includes a second metal tube free end and a second metal tube constraint end, the second device constraint end is configured as the second metal tube constraint end and is close to the working end of the second collimating lens, and the second device free end is configured as the second metal tube free end and is away from the working end of the second collimating lens.

5. The MEMS optical fiber strain sensor according to claim 4, It is characterized in that The distance from the first metal tube constraint end to the second metal tube constraint end is set to a length D1, and the distance from the first metal tube free end to the first metal constraint end is set to a length D2; so that when the linear thermal expansion coefficient of the first metal material is A1 and the linear thermal expansion coefficient of the second metal material is A2, D1*A1-D2*A2=0 is satisfied.

6. The MEMS optical fiber strain sensor according to claim 1, It is characterized in that The first device restraining end and the second device restraining end are respectively welded and fixed on the supporting base.

7. The MEMS optical fiber strain sensor according to claim 1, It is characterized in that The first metal material is composed of 4J36, and the second metal material is composed of nickel with a purity of 99%.

8. The MEMS optical fiber strain sensor according to claim 1, It is characterized in that A dust cover is disposed between the first component and the second component, and the dust cover is configured to cover and seal a gap between the first component and the second component.

9. The MEMS optical fiber strain sensor according to claim 1, It is characterized in that The support base is configured as a rhombus structure, and an acute angle of the rhombus structure is set to 48°.

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