Fiber bragg grating acceleration sensor with temperature compensation

Abstract

The invention discloses a fiber bragg grating acceleration sensor with a temperature compensation function. The fiber bragg grating acceleration sensor comprises a packaging piece, a vibration pickup block, a supporting rod and a sensing optical fiber inscribed with a temperature compensation fiber bragg grating and an acceleration measurement fiber bragg grating which are connected in series, the packaging piece is rigidly connected with the vibration pick-up block; the supporting rod is matched with the packaging piece and is provided with a through hole, and the through hole is communicated with an inner cavity of the packaging piece; the sensing optical fiber penetrates through a through hole of the supporting rod, the temperature compensation fiber bragg grating is glued on the supporting rod, and the acceleration measurement fiber bragg grating is glued on the vibration pick-up block. Measurement interference of vibration conducted by the packaging piece on the temperature compensation fiber grating is weakened, meanwhile, communication of the temperature compensation fiber grating and an inner cavity of the packaging piece where the acceleration measurement fiber grating is located is maintained, and therefore temperature compensation precision is optimized, and the size of the sensor is greatly reduced. The problem of miniaturization of the fiber grating acceleration sensor with temperature compensation is solved, and the fiber grating acceleration sensor can be used for acceleration measurement in a narrow space.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber sensing, and more particularly, relates to an optical fiber Bragg grating acceleration sensor with temperature compensation. Background Art

[0002] As a new type of photonic device, fiber Bragg grating (FBG) sensors create a spatially periodic refractive index distribution within an optical fiber, altering and controlling the propagation of light within the fiber. These sensors measure changes in the measured quantity by converting changes in the measured quantity into changes in strain or temperature acting on the FBG, which in turn causes changes in the Bragg wavelength of the FBG.

[0003] To achieve high-precision acceleration measurement, a fiber Bragg grating (FBG) accelerometer with temperature compensation has been developed. Its basic structure consists of an acceleration-measuring fiber Bragg grating (FBG) and a temperature-compensating fiber Bragg grating (FBG) connected in series on an optical fiber. The temperature-compensating fiber Bragg grating (FBG) is preferably in a freely extended state to minimize the effect of acceleration on the temperature-compensating fiber Bragg grating (FBG), thereby effectively improving the measurement accuracy of acceleration parameters through differential analysis. Chinese patent document CN117630412A provides a prestressed temperature-compensated fiber Bragg grating (FBG) accelerometer. By prestressing each segment of the temperature-compensating fiber Bragg grating (FBG), the effects of pre-stretching are isolated between the fiber Bragg grating (FBG) used to sense strain caused by acceleration and the fiber Bragg grating used for temperature compensation. This improves the stability of the temperature-compensating fiber Bragg grating and reduces temperature compensation errors caused by vibration sensitivity, thereby improving acceleration detection stability and accuracy.

[0004] However, to ensure that the ambient temperature of the temperature-compensating FBG and the accelerometer FBG are consistent, and to minimize the difference between the measured temperature and the intrinsic temperature of the accelerometer FBG, the temperature-compensating FBG and the accelerometer FBG must be packaged in the same chamber. Furthermore, to minimize the effects of vibration on the temperature-compensating FBG, it must be positioned at a certain distance from the accelerometer FBG. This results in a larger overall volume for the packaged temperature-compensated FBG sensor, making it difficult to simultaneously optimize both sensor accuracy and volume. Summary of the Invention

[0005] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides an embodiment in which the vibration pickup block is rigidly connected to the packaging component, and the support rod is separately matched with the packaging component, so that the acceleration measurement fiber Bragg grating transmits vibration and the temperature compensation fiber Bragg grating buffers vibration, and the acceleration measurement fiber Bragg grating conducts vibration and the temperature compensation fiber Bragg grating buffers vibration, thereby improving the temperature compensation accuracy while reducing the volume of the packaging component, thereby solving the technical problem of optimizing the sensor accuracy and sensor volume at the same time.

[0006] To achieve the above object, according to one aspect of the present invention, a fiber Bragg grating acceleration sensor with temperature compensation is provided, comprising: a package, a vibration pickup block, a support rod, and a sensing fiber inscribed with a temperature compensation fiber Bragg grating and an acceleration measurement fiber Bragg grating connected in series; The packaging component is rigidly connected to the vibration pickup block; The support rod is matched with the packaging component and has a through hole, which is connected to the inner cavity of the packaging component; The sensing optical fiber passes through the through hole of the supporting rod, the temperature compensation optical fiber Bragg grating is glued on the supporting rod, and the acceleration measurement optical fiber Bragg grating is glued on the vibration pickup block.

[0007] Preferably, in the fiber grating acceleration sensor with temperature compensation, the support rod is thread-fitted, clearance-fitted, or overfitted with the packaging component.

[0008] Preferably, in the fiber grating acceleration sensor with temperature compensation, a gasket and / or adhesive reinforcement is provided between the support rod and the packaging component.

[0009] Preferably, in the fiber grating acceleration sensor with temperature compensation, the temperature compensation fiber grating is in a naturally extended state and is glued and fixed to the supporting rod.

[0010] Preferably, the fiber grating acceleration sensor with temperature compensation has a support rod with an extended semi-cylindrical inner rod, and the inner rod has a packaging groove. The temperature-compensated fiber grating is glued and fixed to the support rod, and the fixing point is preferably set in the packaging groove. There is an airflow groove between the packaging groove and the through hole of the support rod.

[0011] Preferably, in the temperature-compensated fiber Bragg grating acceleration sensor, the support rod comprises a hollow outer rod, the outer rod cooperates with the inner rod to form a support rod inner cavity, and the support rod inner cavity is connected to the packaging component via a through hole of the support rod.

[0012] Preferably, in the fiber grating acceleration sensor with temperature compensation, the sensing optical fiber passes through the through hole and the packaging component in a straight line.

[0013] Preferably, in the fiber Bragg grating acceleration sensor with temperature compensation, the acceleration measuring fiber Bragg grating is in a pre-stretched state.

[0014] Preferably, in the fiber grating acceleration sensor with temperature compensation, the vibration pickup block is a hinged strain beam, and the acceleration measuring fiber grating is fixed to the hinged strain beam by using a two-point package.

[0015] Preferably, the packaging component of the fiber grating acceleration sensor with temperature compensation has an assembly opening, and the assembly opening is rigidly matched with the object to be measured.

[0016] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art: The fiber Bragg grating acceleration sensor with temperature compensation provided by the present invention places the temperature compensation structure outside the sensor package, and cooperates with the package through a support rod to weaken the measurement interference of the temperature compensation fiber Bragg grating caused by the vibration transmitted by the package on the temperature compensation fiber Bragg grating. At the same time, the temperature compensation fiber Bragg grating is maintained in communication with the inner cavity of the package where the acceleration measurement fiber Bragg grating is located, thereby optimizing the temperature compensation accuracy and greatly reducing the size of the sensor, solving the difficulty of miniaturizing the fiber Bragg grating acceleration sensor with temperature compensation, and can be used for acceleration measurement in narrow spaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a front view of a fiber Bragg grating acceleration sensor with temperature compensation provided by an embodiment of the present invention; Figure 2 1 is a top view of a fiber Bragg grating acceleration sensor with temperature compensation provided by an embodiment of the present invention; Figure 3 Schematic diagram of the structure and packaged acceleration measurement fiber Bragg grating provided by an embodiment of the present invention; Figure 4 It is a three-view diagram and a stereoscopic diagram of the support rod structure provided by an embodiment of the present invention; Figure 5 Schematic diagram of the sensor fiber packaging provided by an embodiment of the present invention.

[0018] In all the drawings, the same figure marks are used to represent the same elements or structures, where: 1 is the base of the package, 101 is the fixing table, 102 is the assembly port, 2 is the vibration pickup block, 3 is the inner rod of the non-temperature compensation end support rod, 4 is the outer rod of the non-temperature compensation end support rod, 5 is the upper cover, 6 is the outer rod of the temperature compensation end support rod, 7 is the inner rod of the temperature compensation end support rod, 701 is the packaging groove, 702 is the air flow groove, 703 is the through hole, 8 is the sensing optical fiber, 801 is the temperature compensation fiber Bragg grating, and 802 is the acceleration measurement fiber Bragg grating. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0020] The fiber Bragg grating acceleration sensor with temperature compensation provided by the present invention comprises: a packaging component, a vibration pickup block, a support rod, and a sensing optical fiber inscribed with a temperature compensation fiber Bragg grating and an acceleration measurement fiber Bragg grating connected in series; The packaging component is rigidly connected to the vibration pickup block; the supporting rod cooperates with the packaging component and has a through hole, which is connected to the inner cavity of the packaging component; the sensing optical fiber passes through the through hole of the supporting rod, the temperature compensation optical fiber Bragg grating is glued on the supporting rod, and the acceleration measurement optical fiber Bragg grating is glued on the vibration pickup block.

[0021] When the package is vibrated, the vibration is transmitted to the acceleration-measuring fiber Bragg grating (FBG) via a vibration pickup block rigidly connected to the package. The separate design of the package and the support rod acts as a buffer, weakening the effect of vibration on the temperature-compensating fiber Bragg grating (FBG), thereby improving the accuracy and stability of temperature compensation. At the same time, the package cavity only houses the acceleration-measuring fiber Bragg grating (FBG), eliminating the need for a temperature-compensating fiber Bragg grating (FBG). More importantly, there is no need to isolate the acceleration-measuring fiber Bragg grating from the temperature-compensating fiber Bragg grating to weaken the effect of vibration on the temperature-compensating fiber Bragg grating. The package cavity can only accommodate the vibration pickup block and the acceleration-measuring fiber Bragg grating, significantly reducing its volume. The connected support rod and package cavity ensure that the temperature-compensating fiber Bragg grating and the acceleration-measuring fiber Bragg grating are at the same ambient temperature, further improving the accuracy of temperature compensation.

[0022] Specifically, the support rod and the packaging component are threaded, clearance-fitted, or overfitted. The threaded fit balances fit strength and vibration damping, resulting in a longer sensor life. To further mitigate the impact of packaging component vibration on the temperature-compensated fiber Bragg grating, washers and / or adhesive reinforcement are provided between the support rod and the packaging component. Washers (such as O-rings) and gels have good elasticity and can provide a cushioning and shock-absorbing effect.

[0023] The temperature-compensating fiber Bragg grating is in a naturally extended state and is glued and fixed to the support rod. The support rod has an extended semi-cylindrical inner rod, and the inner rod has a packaging groove. The temperature-compensating fiber Bragg grating is glued and fixed to the support rod, and the fixing point is preferably set in the packaging groove. There is an airflow groove between the packaging groove and the through hole of the support rod. The temperature-compensating fiber Bragg grating is glued and fixed, usually using a capillary structure. During the packaging process, the glue is easy to clog the through hole. This structure isolates the cavity where the temperature-compensating fiber Bragg grating and the acceleration-measuring fiber Bragg grating are located from each other. The ambient temperature measured by the temperature-compensating fiber Bragg grating is significantly different from the intrinsic temperature of the acceleration-measuring fiber Bragg grating. In order to avoid glue clogging the through hole, a semi-cylindrical inner rod is designed. During packaging, the bottom surface of the semi-cylindrical rod faces upward, and the glue is evenly applied in the packaging groove. An airflow groove is provided between the packaging groove and the through hole to ensure connectivity, ensuring that the space where the temperature-compensating fiber Bragg grating in its naturally extended state is located is connected to the inner cavity of the package where the acceleration-measuring fiber Bragg grating is located, thereby reducing temperature measurement differences. The addition of the outer rod, on the one hand, strengthens the protection of the temperature-compensated fiber Bragg grating and extends the service life of the sensor. On the other hand, it forms a relatively closed support rod cavity, maintains the connectivity between the support rod cavity and the package cavity, ensures that the ambient temperature of the temperature-compensated fiber Bragg grating measurement is consistent with that of the acceleration measurement fiber Bragg grating, and further reduces the temperature compensation error.

[0024] The acceleration measuring optical fiber Bragg grating is in a pre-stretched state. The vibration pickup block is a hinged strain beam, and the acceleration measuring optical fiber Bragg grating is fixed to the hinged strain beam by adopting a two-point packaging.

[0025] In a preferred embodiment, coaxially arranged supporting rods are provided on both sides of the packaging component, and the sensing optical fiber passes through the through hole and the packaging component in a straight line.

[0026] In a preferred embodiment, the packaging component has an assembly opening, and the assembly opening is rigidly matched with the object to be measured.

[0027] The following are examples: The fiber Bragg grating acceleration sensor with temperature compensation provided in this embodiment is as follows: Figure 1 、 2 As shown, it includes: a packaging component, a vibration pickup block, a support rod, and a sensing optical fiber inscribed with a temperature compensation fiber Bragg grating and an acceleration measurement fiber Bragg grating in series; The package serves as a sensor housing, and internally houses an acceleration measuring fiber Bragg grating connected in series with a temperature compensating fiber Bragg grating, and a vibration pickup block. The package of this embodiment includes an upper cover and a base, and a fixing platform provided in the base is rigidly connected to the vibration pickup block.

[0028] There are coaxially arranged support rods on both sides of the package, one of which is encapsulated with a temperature-compensated fiber grating and is the temperature-compensated end support rod, and the other side is the non-temperature-compensated end support rod. The sensing optical fiber passes through the support rods and the package on both sides in a straight line, and the two tail ends of the sensing optical fiber pass through the outer rods of the two support rods respectively.

[0029] Vibration pickup block, this embodiment adopts a hinged vibration pickup block, that is, a hinged strain beam, such as Figure 3 As shown, it is made of stainless steel with V-grooves on the top of the two arms. The acceleration measuring fiber Bragg grating is placed in the center of the hinged vibration pickup block and is packaged in a two-point manner. The whole is in a pre-stretched state and is fixed to the V-groove of the hinged vibration pickup block with glue.

[0030] Support rod, such as Figure 4 As shown, it cooperates with the base of the package through its own thread; an O-type rubber ring or glue reinforcement can be set between the support rod and the package, which makes the cooperation more stable on the one hand and plays a role in shock absorption on the other hand. This embodiment adopts glue reinforcement. The support rod has an extended semi-cylindrical inner rod, and the inner rod has a through hole at the center axis, and the through hole is connected to the inner cavity of the package; the inner rod has a packaging groove, which is a semi-circular groove. The temperature-compensating optical fiber Bragg grating is glued and fixed to the support rod, and the fixing point is set in the packaging groove. There is an airflow groove between the packaging groove and the through hole of the support rod. The support rod has a cylindrical hollow outer rod, and the outer rod and the inner rod are coaxially sleeved and threaded to form a relatively closed support rod inner cavity, which keeps the support rod inner cavity connected with the inner cavity of the package.

[0031] The sensing fiber is straight, e.g. Figure 5 As shown, it falls into the V groove of the hinged vibration pickup block and the semicircular grooves of the two side support rods. The temperature compensation fiber Bragg grating is in a natural extension state and is glued and fixed to the support rod. The acceleration measurement fiber Bragg grating is in a pre-stretched state and is fixed to the hinged strain beam. After the sensing fiber is packaged on the support rod and the base, the upper cover and the base are screwed together. The fixing points are as follows Figure 5 The blue part is schematic.

[0032] The base of the package has an assembly port that rigidly fits the object to be measured. In actual use, if the surface of the object to be measured is made of magnetic material, a strong magnetic seat can be installed using the assembly port at the bottom of the base, and then the sensor can be adsorbed on the object to be measured. If the surface of the object to be measured is not made of magnetic material, the sensor can also be fixed to the surface of the object to be measured with resin. After the sensor is fixed, the sensor signal output end is connected to the fiber optic sensor demodulator. By converting the change in the wavelength of the fiber grating into the change in acceleration, the acceleration of the object to be measured can be measured.

[0033] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fiber Bragg grating acceleration sensor with temperature compensation, characterized in that: include: A packaging component, a vibration pickup block, a support rod, and a sensing optical fiber inscribed with a temperature compensation fiber Bragg grating and an acceleration measurement fiber Bragg grating in series; The packaging component is rigidly connected to the vibration pickup block; The support rod is matched with the packaging component and has a through hole, which is connected to the inner cavity of the packaging component; The sensing optical fiber passes through the through hole of the supporting rod, the temperature compensation optical fiber Bragg grating is glued on the supporting rod, and the acceleration measurement optical fiber Bragg grating is glued on the vibration pickup block.

2. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 1, wherein: The support rod is thread-fitted, clearance-fitted, or over-fitted with the packaging component.

3. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 2, wherein: A gasket and / or adhesive reinforcement is provided between the support rod and the packaging component.

4. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 1, wherein: The temperature-compensating optical fiber Bragg grating is in a naturally extended state and is glued and fixed to the supporting rod.

5. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 4, wherein: The support rod has an extended semi-cylindrical inner rod with a packaging groove on the inner rod. The temperature-compensating fiber grating is glued and fixed to the support rod. The fixing point is preferably set in the packaging groove. There is an airflow groove between the packaging groove and the through hole of the support rod.

6. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 5, wherein: The support rod has a hollow outer rod, and the outer rod cooperates with the inner rod to form a support rod inner cavity, and the support rod inner cavity is communicated with the packaging component through the through hole of the support rod.

7. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 6, wherein: The sensing optical fiber passes through the through hole and the packaging component in a straight line.

8. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 1, wherein: The acceleration measuring fiber Bragg grating is in a pre-stretched state.

9. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 1, wherein: The vibration pickup block is a hinged strain beam, and the acceleration measurement optical fiber Bragg grating is fixed to the hinged strain beam by adopting a two-point package.

10. The fiber Bragg grating acceleration sensor with temperature compensation according to claim 1, wherein: The packaging component has an assembly opening, and the assembly opening is rigidly matched with the object to be measured.

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