A self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor

Abstract

The present invention belongs to the field of high-temperature sensing, and discloses a self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor, comprising: a packaging base, a packaging cover plate, a packaging sleeve, an optical fiber, a Bragg fiber grating, and a sensitive diaphragm; the packaging cover plate is fixedly connected to the packaging base, a first diaphragm groove is arranged at the top of the packaging base, a second diaphragm groove is arranged at the bottom of the packaging cover plate, and the first diaphragm groove and the second diaphragm groove are arranged oppositely to form a vibration space for the sensitive diaphragm; the Bragg fiber grating is provided with a first Bragg grating and a second Bragg grating, the first Bragg grating is fixed on the packaging cover plate, and the second Bragg grating is fixedly arranged on the sensitive diaphragm; one end of the optical fiber is fixedly arranged in the central through hole and is encapsulated by the packaging sleeve fixed on the top of the packaging cover plate; the optical fiber end face and the sensitive diaphragm form a resonant cavity. The present invention can synchronously monitor temperature and vibration signals under high-temperature conditions, and realize self-calibration of vibration signals, thereby improving measurement accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of high-temperature sensing, and particularly relates to a self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor. Background Art

[0002] With the rapid development of aerospace technology, solid rocket motors have shown broad application prospects in many key fields such as space transportation and missile launch due to their simple structure and high reliability. However, during the combustion process of the solid rocket motor combustion chamber, there are often situations where the fuel burns incompletely, and problems such as high temperature, high pressure, and strong vibration occur, causing irreversible damage to the engine structure and even triggering serious safety accidents. Currently, traditional silicon-based electrical sensors are difficult to work properly in harsh environments such as high temperature and strong corrosion, which greatly limits their application in the monitoring of solid rocket motors.

[0003] Fiber optic sensors have the advantages of anti-electromagnetic interference, intrinsic safety, corrosion resistance, etc., and are widely used in extremely harsh environments. Among them, sensors made of fiber Bragg gratings can achieve precise measurement of different physical quantities, and have the advantages of a wide application range, high measurement resolution, and many measurable physical quantities. Fiber Bragg grating sensors have developed rapidly in the past few decades and have been applied to many fields such as bridge monitoring, aerospace, petrochemical industry, etc. In the actual application process, temperature and vibration, as two important physical parameters, their changes can often directly reflect the state and safety of an object. However, at present, fiber Bragg grating sensors can often only achieve single-parameter measurement at a certain point, and cannot simultaneously measure temperature and vibration dual parameters. This limitation greatly restricts the application range of fiber Bragg grating sensors in complex environments, so that in occasions where temperature and vibration need to be monitored simultaneously, multiple sensors have to be used for separate measurements, which not only increases the complexity and cost of the system, but also may lead to large errors in the measurement results due to the mutual influence between sensors.

[0004] In addition, generally speaking, fiber grating vibration sensors have the advantages of good stability and consistency, but have problems such as high cross-sensitivity and thermal mismatch at the connection with the cantilever beam at high temperatures; while Fabry-Perot cavity vibration sensors have poor stability and consistency, but low cross-sensitivity, almost no thermal mismatch problem, and higher temperature resistance. Summary of the Invention

[0005] In order to overcome the problem that it is difficult for fiber optic sensors to synchronously and accurately obtain temperature and vibration signals in high-temperature harsh environments in the prior art, the present invention proposes a self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor to achieve accurate measurement of temperature and vibration signals in harsh environments such as high temperature and strong vibration.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor, comprising: a packaging base, a packaging cover plate, a packaging sleeve, an optical fiber, a Bragg fiber grating, and a sensitive diaphragm;

[0007] The packaging cover plate is fixedly connected to the packaging base. A first diaphragm groove is provided at the top of the packaging base, and a second diaphragm groove is provided at the bottom of the packaging cover plate. The first diaphragm groove and the second diaphragm groove are arranged opposite to each other to form a vibration space for the sensitive diaphragm; A central through hole located at the center of the second diaphragm groove is provided on the packaging cover plate;

[0008] The sensitive diaphragm includes a bracket, a cantilever beam, and a mass block connected in sequence. The bracket is fixedly connected to the packaging cover plate. The mass block is arranged in the vibration space. The Bragg fiber grating is provided with a first Bragg grating and a second Bragg grating with different central wavelengths. The first Bragg grating is fixed on the packaging cover plate, and the second Bragg grating is fixedly arranged on the sensitive diaphragm;

[0009] One end of the optical fiber is fixedly arranged in the central through hole and is encapsulated by a packaging sleeve fixed on the top of the packaging cover plate; The end face of the optical fiber and the sensitive diaphragm form a resonant cavity.

[0010] The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor further includes a hollow tube. One end of the optical fiber is fixed in the hollow tube by a high-temperature inorganic glue; The hollow tube is fixed in the central through hole of the packaging cover plate by a high-temperature inorganic glue.

[0011] The materials of the packaging base, the packaging cover plate, and the packaging sleeve are stainless steel, and the materials of the optical fiber, the Bragg fiber grating, the sensitive diaphragm, and the hollow tube are sapphire.

[0012] The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor further includes a packaging substrate. The packaging substrate is fixed at the bottom of the packaging base and is fixedly connected to the packaging base and the packaging cover plate by bolts. An installation threaded hole for connecting a test component is provided at the center of the bottom of the packaging substrate.

[0013] The wavelength of the first Bragg grating is 1545 nm, and the wavelength of the second Bragg grating is 1550 nm. The first Bragg grating is fixed to the sensitive diaphragm by a high-temperature inorganic glue, and the second Bragg grating is fixed to the packaging cover plate by a high-temperature inorganic glue.

[0014] A spherical optical fiber portion is provided at the end of the Bragg fiber grating located in the vibration space.

[0015] The sensitive diaphragm is of a single cantilever beam structure. A sunk groove connected to the second diaphragm groove is further provided at the bottom of the encapsulation cover plate. The sunk groove is used for fixedly arranging the bracket, and thus fixedly arranging the sensitive diaphragm.

[0016] The mass block, the first diaphragm groove and the second diaphragm groove are all square, and the bracket is an isosceles triangle. One end of the cantilever beam is connected to the top angle of the bracket, and the other end is connected to one of the angles of the mass block.

[0017] A plurality of fourth threaded holes are provided on the encapsulation cover plate. The encapsulation cover plate is fixedly connected to the encapsulation base through bolts arranged in the fourth threaded holes. A plurality of fifth through holes are provided on the encapsulation sleeve. The encapsulation sleeve is fixedly connected to the encapsulation cover plate and the encapsulation base through bolts arranged in the fifth through holes.

[0018] The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor further includes a first fiber optic armored tube and a second fiber optic armored tube;

[0019] The first fiber optic armored tube is arranged on the encapsulation sleeve. A sixth threaded hole is provided on the encapsulation sleeve. The sixth threaded hole is used for arranging bolts to fix the first fiber optic armored tube. The first fiber optic armored tube is used for protecting the optical fiber;

[0020] The second fiber optic armored tube is arranged between the encapsulation base and the encapsulation cover plate. A fifth threaded hole is provided on the encapsulation cover plate. The fifth threaded hole is used for arranging bolts to fix the second fiber optic armored tube. The second fiber optic armored tube is used for protecting the Bragg fiber grating.

[0021] The present invention has the following beneficial effects compared with the prior art:

[0022] 1. The present invention provides a self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor, which uses two Bragg gratings with different central wavelengths to realize the dual-parameter measurement of temperature and vibration; wherein the first Bragg grating is fixed on the surface of the encapsulation cover plate and is only sensitive to temperature. By observing the drift amount of its central wavelength, the actual temperature change can be detected. At the same time, the second Bragg grating is fixed on the surface of the sapphire sensitive diaphragm and is sensitive to both vibration and temperature. By measuring the drift amount of its central wavelength, the change of the superposition of the actual temperature and vibration can be detected. At the same time, by using the drift amount of the central wavelength of the first Bragg grating to calibrate the drift amount of the central wavelength of the second Bragg grating, the influence of temperature change on the central wavelength of the second Bragg grating can be eliminated, and the magnitudes of the temperature and vibration signals in the environment can be calculated simultaneously, and the consistency of the measurement data is strong.

[0023] 2. Moreover, the sensor of the present invention is also provided with a vibration measurement sensor formed by a Fabry-Perot cavity. It forms a Fabry-Perot resonant cavity between a sapphire optical fiber and a sapphire sensitive diaphragm. By demodulating the interference optical signal output from the cavity, the magnitude of the vibration signal can be obtained. In the present invention, the vibration signals of the same sensitive unit are measured simultaneously by a fiber Bragg grating and a Fabry-Perot cavity. By using the two vibration signals to characterize the vibration simultaneously, the error caused by the contingency of a single data can be reduced, thereby solving the problems of high cross-sensitivity of the fiber Bragg grating vibration measurement sensor and thermal mismatch at high temperatures, as well as the poor stability and consistency of the Fabry-Perot cavity vibration measurement sensor. The accuracy of the measurement data is improved through self-calibration. Specifically, a more accurate measurement result can be obtained by taking the average value of the two signals.

[0024] 3. In the present invention, the sensor forms a packaging housing through a packaging base, a packaging cover plate, and a packaging sleeve. The packaging housing is made of 310S stainless steel material, realizing a fully rigid connection between the packages, ensuring the stability of the optical sensing signal of the sensor under different temperatures and vibrations, and improving the test accuracy of the sensor in a high-temperature environment. Moreover, the working area of the sensor is completely composed of sapphire material, forming a homogeneous integration of sapphire material, which can achieve stable sensing performance in a high-temperature environment and prevent the problem of thermal effect mismatch caused by different material thermal expansion coefficients.

[0025] In summary, the present invention proposes a fiber optic sensor integrating temperature and vibration dual parameters, which can not only realize the synchronous monitoring of temperature and vibration signals, but also measure the vibration signals of the same sensitive unit simultaneously through a Fabry-Perot cavity, enabling self-calibration of the vibration signals, improving the consistency and accuracy of the measurement data, and breaking through the working temperature limit of traditional sensors. It can not only realize the synchronous acquisition of temperature and vibration signals in the combustion field of a solid rocket engine, but also broaden the working frequency band of the sensor, and has practical application value in high-temperature and strong vibration environments in the fields of aerospace, missile launch, and non-destructive testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional schematic diagram of a high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor with a self-calibration function provided by an embodiment of the present invention;

[0027] Figure 2 It is a three-dimensional structure schematic diagram of a high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor with a self-calibration function provided by an embodiment of the present invention;

[0028] Figure 3 It is a three-dimensional assembly schematic diagram of a packaging cover plate, a sapphire sensitive diaphragm, and a sapphire Bragg grating in an embodiment of the present invention;

[0029] Figure 4Schematic cross-sectional structure diagram of the encapsulation substrate in the embodiment of the present invention;

[0030] Figure 5 Schematic three-dimensional structure diagram of the encapsulation base in the embodiment of the present invention;

[0031] Figure 6 Schematic three-dimensional structure diagram of the encapsulation cover plate in the embodiment of the present invention;

[0032] Figure 7 Schematic three-dimensional structure diagram of the encapsulation sleeve in the embodiment of the present invention;

[0033] Figure 8 Schematic three-dimensional structure diagram of the sapphire sensitive diaphragm in the embodiment of the present invention;

[0034] Figure 9 Schematic diagram of the reflection spectrum of the Bragg grating optical fiber in the embodiment of the present invention;

[0035] Figure 10 Schematic diagram of the reflection spectrum of the Fabry-Perot cavity in the embodiment of the present invention;

[0036] In the figure: 2 - encapsulation base, 3 - encapsulation cover plate, 4 - encapsulation sleeve, 5 - first optical fiber armor tube, 6 - optical fiber, 7 - second optical fiber armor tube, 8 - Bragg fiber grating, 9 - hollow tube, 10 - sensitive diaphragm, 11 - encapsulation substrate, 21 - second threaded hole, 22 - first long groove, 23 - first diaphragm groove, 24 - fifth through hole, 25 - first through hole, 31 - first threaded hole, 32 - fourth through hole, 33 - fourth threaded hole, 34 - third through hole, 35 - second long groove, 36 - third long groove, 37 - counterbore, 38 - second diaphragm groove, 39 - central through hole, 41 - second through hole, 42 - circular groove, 43 - third threaded hole, 81 - first Bragg grating, 82 - second Bragg grating, 83 - spherical optical fiber, 101 - bracket, 102 - single cantilever beam, 103 - mass block, 111 - mounting threaded hole, 112 - fifth threaded hole. Detailed implementation manners

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0038] As Figures 1 to 8As shown in the figure, an embodiment of the present invention provides a high-temperature-resistant optical fiber temperature-vibration dual-parameter sensor with a self-calibration function, which includes a packaging base 2, a packaging cover 3, a packaging sleeve 4, an optical fiber 6, a Bragg optical fiber grating 8, and a sensitive diaphragm 10.

[0039] Among them, the packaging cover 3 is fixedly connected to the packaging base 2. A first diaphragm groove 23 is etched on the top of the packaging base 2, and a second diaphragm groove 38 is etched on the bottom of the packaging cover 3. The first diaphragm groove 23 and the second diaphragm groove 38 are arranged opposite to each other to form a vibration space for the sensitive diaphragm 10. A central through hole 39 located at the center of the second diaphragm groove 38 is provided on the packaging cover 3.

[0040] Among them, the sensitive diaphragm 10 includes a bracket 101, a cantilever beam 102, and a mass block 103 connected in sequence. The bracket 101 is fixedly connected to the packaging cover 3. The mass block 103 is arranged in the vibration space. First Bragg gratings 81 and second Bragg gratings 82 with different central wavelengths are provided on the Bragg optical fiber grating 8. The first Bragg grating 81 is fixed on the packaging cover 3, and the second Bragg grating 82 is fixedly arranged on the sensitive diaphragm 10.

[0041] Among them, one end of the optical fiber 6 is fixedly arranged in the central through hole 39 and is encapsulated by the packaging sleeve 4 fixed on the top of the packaging cover 3. The end face of the optical fiber 6 and the sensitive diaphragm 10 form a resonant cavity.

[0042] Furthermore, a self-calibration high-temperature-resistant optical fiber temperature-vibration dual-parameter sensor of this embodiment further includes a hollow tube 9. One end of the optical fiber 6 is fixed in the hollow tube 9 by a high-temperature inorganic adhesive. The hollow tube 9 is fixed in the central through hole 39 of the packaging cover 3 by a high-temperature inorganic adhesive.

[0043] In this embodiment, the materials of the packaging base 2, the packaging cover 3, and the packaging sleeve 4 are stainless steel, and the materials of the optical fiber 6, the Bragg optical fiber grating 8, and the sensitive diaphragm 10 are sapphire.

[0044] Furthermore, a self-calibration high-temperature-resistant optical fiber temperature-vibration dual-parameter sensor of this embodiment further includes a packaging substrate 11. The packaging substrate 11 is fixed to the bottom of the packaging base 2. The packaging base 2 and the packaging cover 3 are fixedly arranged on the packaging substrate 11 by bolts. As Figure 8As shown, an installation threaded hole 111 for connecting a test component is provided at the center of the bottom of the encapsulation base 11. By providing the encapsulation base 11, when installing the sensor, the encapsulation base 11 can be connected to the component to be measured through the screw in the installation threaded hole 111 first, and then the sensor can be fixed by connecting the encapsulation cover plate 3 and the encapsulation base 2 through bolts and then connecting to the encapsulation base 11, so as to avoid damage to the optical fiber caused by the rotation process during the installation of the sensor.

[0045] Specifically, in this embodiment, the wavelength of the first Bragg grating 81 is 1545 nm, the wavelength of the second Bragg grating 82 is 1550 nm. The first Bragg grating 81 is fixed to the sensitive diaphragm 10 by a high-temperature inorganic adhesive, and the second Bragg grating 82 is fixed to the encapsulation cover plate 3 by a high-temperature inorganic adhesive. Specifically, the first Bragg grating 81 and the second Bragg grating 82 can be formed by femtosecond laser inscription inside the optical fiber. Among them, the first Bragg grating 81 is pasted on the surface of the encapsulation cover plate 3 and is only sensitive to temperature. The actual temperature change is detected by observing the drift of its central wavelength. At the same time, the second Bragg grating 82 is pasted on the surface of the sapphire sensitive diaphragm 10 and is sensitive to both vibration and temperature. The change of the superposition of the actual temperature and vibration is detected by observing the drift of its central wavelength. By using the first Bragg grating 81 to compensate the second Bragg grating 82, the magnitudes of the temperature and vibration signals in the environment can be calculated simultaneously.

[0046] Further, in this embodiment, a spherical optical fiber portion 83 is provided at the tail end of the Bragg optical fiber grating 8 located in the vibration space. Specifically, the tail end of the Bragg optical fiber grating 8 is burned into a ball using an optical fiber fusion splicer to form the spherical optical fiber 83. Forming the spherical optical fiber 83 through the ball-burning process can effectively increase the return loss and improve the spectral signal-to-noise ratio.

[0047] Further, as Figure 3 and 7 shown, in this embodiment, the sensitive diaphragm 10 is of a single cantilever beam structure, and the bracket 101 is connected to the mass block 103 through a cantilever beam 102. As Figure 5 shown, a sink 37 connected to the second diaphragm groove 38 is further provided at the bottom of the encapsulation cover plate 3. The sink 37 is used to fixedly arrange the bracket 101, and thus fixedly arrange the sensitive diaphragm 10. The depth of the sink 37 is less than that of the second diaphragm groove 38, so the gap between the second diaphragm groove 38 and the mass block 103 forms the upward vibration space of the mass block 103 of the sensitive diaphragm 10. In addition, the gap between the first diaphragm groove 23 at the top of the encapsulation base 2 and the mass block 103 forms the downward vibration space of the mass block 103 of the sensitive diaphragm 10.

[0048] Further, in this embodiment, the mass block 103, the first diaphragm groove 23, and the second diaphragm groove 38 are all square, and the bracket 101 is an isosceles triangle. One end of the cantilever beam 102 is connected to the apex angle of the bracket 101, and the other end is connected to one of the corners of the mass block 103. In addition, the mass block 103, the first diaphragm groove 23, and the second diaphragm groove 38 are arranged in a 45° staggered manner, and the side lengths of the first diaphragm groove 23 and the second diaphragm groove 38 are greater than the diagonal length of the square mass block 103.

[0049] Further, in this embodiment, a plurality of first threaded holes 31 are provided on the encapsulation cover plate 3, and first through holes 25 are provided at positions corresponding to the first threaded holes 31 on the encapsulation base 2. The encapsulation base 2 is fixedly connected to the encapsulation cover plate 3 by bolts provided in the first through holes 25 and the first threaded holes 31; a plurality of second through holes 41 are provided on the encapsulation sleeve 4, third through holes 34 are provided at positions corresponding to the second through holes 41 on the encapsulation cover plate 3, and second threaded holes 21 are provided at positions corresponding to the second through holes 41 on the encapsulation base 2. Bolts provided in the second through holes 41, the third through holes 34, and the second threaded holes 21 fixedly connect the encapsulation sleeve 4 to the encapsulation cover plate 3 and the encapsulation base 2 together.

[0050] Further, as Figures 1 to 2 shown, a self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor according to this embodiment further includes a first fiber optic armored tube 5 and a second fiber optic armored tube 7; the first fiber optic armored tube 5 is arranged on the encapsulation sleeve 4, and two third threaded holes 43 are provided on the encapsulation sleeve 4. The third threaded holes 43 are used for setting bolts to fix the first fiber optic armored tube 5, and the first fiber optic armored tube 5 is used to protect the optical fiber 6; the second fiber optic armored tube 7 is arranged between the encapsulation base 2 and the encapsulation cover plate 3, and two fourth threaded holes 33 are provided on the encapsulation cover plate 3. The fourth threaded holes 33 are used for setting bolts to fix the second fiber optic armored tube 7, and the second fiber optic armored tube 7 is used to protect the Bragg fiber grating 8.

[0051] Further, in this embodiment, a plurality of fourth through holes 32 are further provided on the encapsulation cover plate 3, fifth through holes 24 are provided at positions corresponding to the fourth through holes 32 on the encapsulation base 2, and fifth threaded holes 112 are provided at positions corresponding to the fourth through holes 32 on the encapsulation substrate 11. Then, bolts provided in the fourth through holes 32, the fifth through holes 24, and the fifth threaded holes 112 fixedly connect the encapsulation cover plate 3, the encapsulation base 2, and the encapsulation substrate 11 together.

[0052] Further, in this embodiment, first long slots 22 and second long slots 35 are respectively provided at positions corresponding to the second optical fiber armored tube 7 on the encapsulation base 2 and the encapsulation cover plate 3. The first long slots 22 and the second long slots 35 form a receiving space for the second optical fiber armored tube 7. Further, in addition, a third long slot 36 is provided between the second long slot 35 and the sunk slot 37. The third long slot 36 is used to arrange the optical fiber section where the first Bragg grating of the Bragg optical fiber grating 8 is located.

[0053] Further, in this embodiment, the encapsulation sleeve 4 includes a flat plate portion and a top protrusion. The second through hole 41 is provided on the flat plate portion, and the third threaded hole 43 is provided on the top protrusion. A round slot 42 is provided inside the top protrusion for receiving the hollow tube 9.

[0054] In addition, an assembly method of the high-temperature resistant optical fiber temperature-vibration dual-parameter sensor with self-calibration function provided by an embodiment of the present invention includes the following steps:

[0055] Step S1: Place the pre-cleaned sensitive diaphragm 10 on the encapsulation cover plate 3, and evenly apply high-temperature inorganic glue between the encapsulation cover plate 3 and the sensitive diaphragm 10, and cure the high-temperature inorganic glue by baking in an oven.

[0056] Step S2: Place the Bragg optical fiber grating 8 written by femtosecond laser on the encapsulation cover plate 3 and the sapphire sensitive diaphragm 10. In a fully pasted manner, evenly apply high-temperature inorganic glue at the positions where the Bragg optical fiber grating 8 contacts the encapsulation cover plate 3 and the sensitive diaphragm 10, and cure the high-temperature inorganic glue by baking in an oven.

[0057] Step S3: Use screws to tightly connect the encapsulation cover plate 3 and the encapsulation base 2.

[0058] Step S4: Insert the head of the optical fiber 6 wrapped by the hollow tube 9 into the central through hole 39 of the encapsulation cover plate 3, and evenly apply high-temperature inorganic glue at the connection between the encapsulation cover plate 3 and the sapphire hollow tube 9, and cure the high-temperature inorganic glue by baking in an oven.

[0059] Step S5: Use screws to tightly connect the encapsulation sleeve 4, the encapsulation cover plate 3 and the encapsulation base 2.

[0060] Step S6: Use screws to set the encapsulation base on the component to be measured, and then pass the screws through the encapsulation cover plate 3 and the encapsulation base 2 to tightly connect with the encapsulation base 11.

[0061] Specifically, in this embodiment, step S3 further includes the following steps:

[0062] Insert the second optical fiber armored tube 7 outside the fiber Bragg grating 8 and extend it into the first long groove 22 and the second long groove 35 of the encapsulation cover plate 3 and the encapsulation base 2, and fix the second optical fiber armored tube 7 with screws arranged in a plurality of fourth threaded holes 33;

[0063] Step S5 further includes the following steps:

[0064] Insert the first optical fiber armored tube 5 outside the optical fiber 6 and extend it into the encapsulation sleeve 4, and fix the second optical fiber armored tube 7 with screws arranged at a plurality of third threaded holes 43.

[0065] In this embodiment, the amplified spontaneous emission light source enters the fiber Bragg grating 8 through the fiber optic circulator, and the reflected light generated by the grating region enters the spectrometer through the fiber optic circulator. The obtained spectral signal is as Figure 9 shown. By demodulating the jitter of the reflected spectrum of the second Bragg grating 82 near its central wavelength, a vibration signal can be obtained.

[0066] In this embodiment, the amplified spontaneous emission light source enters the optical fiber 6 through the fiber optic circulator, and multi-beam interference occurs between the end face of the optical fiber 6 and the surface of the sensitive diaphragm 10. The interference light enters the spectrometer through the fiber optic circulator. The obtained spectral signal is as Figure 10 shown. By collecting the change of the free spectral range of the spectrum over time, the demodulation of the vibration signal can be realized.

[0067] In summary, the present invention proposes a self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor, which realizes the synchronous measurement of temperature and vibration dual-parameters by observing the drift of the central wavelengths of two groups of Bragg gratings with different central wavelengths. Moreover, in the present invention, a Fabry-Perot resonator is formed by the sensitive diaphragm and the sapphire optical fiber to calibrate the vibration signal, improving the test range and accuracy. In addition, in the present invention, the encapsulation housing is rigidly connected by stainless steel, ensuring the stability of the optical sensing signal of the sensor under different temperatures and vibrations, improving the test accuracy of the sensor in a high-temperature environment, breaking through the working temperature limit of traditional sensors, broadening the working frequency band of the sensor, and having practical application value in high-temperature and strong-vibration environments such as aerospace, missile launch, and non-destructive testing.

[0068] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-calibrating high-temperature-resistant optical fiber temperature-vibration dual-parameter sensor, characterized in that Comprising: An encapsulation base (2), an encapsulation cover plate (3), an encapsulation sleeve (4), an optical fiber (6), a Bragg fiber grating (8), and a sensitive diaphragm (10); The encapsulation cover plate (3) is fixedly connected to the encapsulation base (2). A first diaphragm groove (23) is provided at the top of the encapsulation base (2), and a second diaphragm groove (38) is provided at the bottom of the encapsulation cover plate (3). The first diaphragm groove (23) and the second diaphragm groove (38) are oppositely arranged to form a vibration space for the sensitive diaphragm (10). A central through hole (39) located at the center of the second diaphragm groove (38) is provided on the encapsulation cover plate (3); The sensitive diaphragm (10) includes a bracket (101), a cantilever beam (102), and a mass block (103) connected in sequence. The bracket (101) is fixedly connected to the encapsulation cover plate (3). The mass block (103) is arranged in the vibration space. The Bragg fiber grating (8) is provided with a first Bragg grating (81) and a second Bragg grating (82) with different central wavelengths. The first Bragg grating (81) is fixed on the encapsulation cover plate (3), and the second Bragg grating (82) is fixedly arranged on the sensitive diaphragm (10); One end of the optical fiber (6) is fixedly arranged in the central through hole (39) and is encapsulated by the encapsulation sleeve (4) fixed on the top of the encapsulation cover plate (3). The end face of the optical fiber (6) and the sensitive diaphragm (10) form a resonant cavity.

2. The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor according to claim 1, characterized in that It further includes a hollow tube (9). One end of the optical fiber (6) is fixed in the hollow tube (9) by a high-temperature inorganic adhesive. The hollow tube (9) is fixed in the central through hole (39) of the encapsulation cover plate (3) by a high-temperature inorganic adhesive.

3. The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor according to claim 2, wherein The materials of the encapsulation base (2), the encapsulation cover plate (3), and the encapsulation sleeve (4) are stainless steel, and the materials of the optical fiber (6), the Bragg fiber grating (8), the sensitive diaphragm (10), and the hollow tube (9) are sapphire.

4. The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor according to claim 1, wherein It further includes an encapsulation base (11). The encapsulation base (11) is fixed at the bottom of the encapsulation base (2) and is fixedly connected to the encapsulation base (2) and the encapsulation cover plate (3) by bolts. An installation threaded hole (111) for connecting a test component is provided at the center of the bottom of the encapsulation base (11).

5. A self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor according to claim 1, characterized in that, The wavelength of the first Bragg grating (81) is 1545 nm, and the wavelength of the second Bragg grating (82) is 1550 nm. The first Bragg grating (81) is fixed to the sensitive diaphragm (10) by a high-temperature inorganic adhesive, and the second Bragg grating (82) is fixed to the encapsulation cover plate (3) by a high-temperature inorganic adhesive.

6. The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor according to claim 1, characterized in that, A spherical optical fiber part (83) is provided at the tail end of the Bragg fiber grating (8) located in the vibration space.

7. The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor according to claim 1, wherein, The sensitive diaphragm (10) is of a single-cantilever beam structure. A sunk groove (37) connected to the second diaphragm groove (38) is further provided at the bottom of the encapsulation cover plate (3). The sunk groove (37) is used for fixedly arranging the bracket (101) and further fixing the sensitive diaphragm (10).

8. A self-calibrating high-temperature-resistant optical fiber temperature-vibration dual-parameter sensor according to claim 7, characterized in that, The mass block (103), the first diaphragm groove (23) and the second diaphragm groove (38) are all square, and the bracket (101) is an isosceles triangle. One end of the cantilever beam (102) is connected to the vertex angle of the bracket (101), and the other end is connected to one of the corners of the mass block (103).

9. The self-calibrating high-temperature-resistant optical fiber temperature-vibration dual-parameter sensor according to claim 6, characterized in that A plurality of fourth threaded holes (31) are provided on the encapsulation cover plate (3). The encapsulation cover plate (3) is fixedly connected to the encapsulation base (2) by bolts provided in the fourth threaded holes (31). A plurality of fifth through holes (41) are provided on the encapsulation sleeve (4). The encapsulation sleeve (4) is fixedly connected to the encapsulation cover plate (3) and the encapsulation base (2) by bolts provided in the fifth through holes (41).

10. The self-calibrating high-temperature-resistant fiber optic temperature-vibration dual-parameter sensor according to claim 6, characterized in that, It further includes a first optical fiber armored tube (5) and a second optical fiber armored tube (7); The first optical fiber armored tube (5) is provided on the encapsulation sleeve (4). A sixth threaded hole (43) is provided on the encapsulation sleeve (4). The sixth threaded hole (43) is used to set bolts to fix the first optical fiber armored tube (5). The first optical fiber armored tube (5) is used to protect the optical fiber (6); The second optical fiber armored tube (7) is provided between the encapsulation base (2) and the encapsulation cover plate (3). A fifth threaded hole (33) is provided on the encapsulation cover plate (3). The fifth threaded hole (33) is used to set bolts to fix the second optical fiber armored tube (7). The second optical fiber armored tube (7) is used to protect the Bragg fiber grating (8).

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