Miniaturized three-axis high-temperature-resistant optical fiber MEMS vibration sensor

Abstract

The invention discloses a miniaturized three-axis high-temperature-resistant optical fiber MEMS vibration sensor which comprises a vibration sensitive structure, a collimation cover plate, an optical fiber and a collimation tube. The vibration sensitive structure comprises an integrated frame and three groups of beam-mass block structures embedded in the integrated frame; the tail ends of the x-axis light-emitting optical fiber and the y-axis light-emitting optical fiber are cut in the 45-degree direction to form inclined end faces, the tail ends of the inclined end faces are ground to form grinding planes, and an FP cavity is formed between the grinding planes and the surface of the mass block. The x-axis collimation cover plate and the y-axis collimation cover plate are provided with grooves, optical fibers are arranged at the bottoms of the grooves, and the x-axis collimation cover plate and the y-axis collimation cover plate are bonded with the integrated frame and can measure vibration of the x axis and the y axis. The z-axis light-emitting optical fiber is a 90-degree cut optical fiber, and an FP cavity is formed between the 90-degree cut end face and the surface of the mass block. The z-axis light-emitting optical fiber penetrates into the collimator tube and the z-axis collimation cover plate, and the z-axis collimation cover plate is bonded with the integrated frame, so that the z-axis vibration can be measured. According to the invention, miniaturization, high temperature resistance and triaxial vibration measurement can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of vibration sensors, and in particular relates to a miniaturized three-axis high-temperature-resistant optical fiber MEMS vibration sensor. Background Art

[0002] Vibration has an important impact on the performance and safety of advanced equipment such as aircraft engines, so measuring vibration is a very important technology. The fiber FP (Fabry-Perot) cavity vibration sensor measures vibration by measuring the change in the length of the fiber FP cavity. Compared with traditional electrical vibration sensors, the fiber FP vibration sensor has many advantages. The fiber FP vibration sensor has the advantages of anti-electromagnetic interference, high temperature resistance, corrosion resistance, and good reliability. It can adapt to the harsh environment of high temperature, low temperature and strong vibration in the aerospace environment, and has broad prospects in the application of aerospace. Due to the limited space for installing vibration sensors in narrow environments such as aircraft engines, the requirements of miniaturization, high temperature resistance, and triaxial vibration testing are put forward for fiber optic vibration sensors. At present, scholars at home and abroad have studied various structures of fiber optic FP vibration sensors. Some of them are miniaturized in size, but can only measure single-axis vibration; some can measure multi-axis vibration, but the size is still large and not resistant to high temperature, which cannot meet the installation space of the aerospace environment. Miniaturization and high temperature resistance of vibration sensors are required. Therefore, it is of great practical application value to study miniaturized, high-temperature resistant, and triaxial vibration-measuring fiber FP vibration sensors that meet the installation and monitoring needs. Summary of the invention

[0003] The purpose of the present invention is to provide a miniaturized three-axis high-temperature resistant optical fiber MEMS vibration sensor, which can achieve miniaturization, high-temperature resistance and three-axis vibration measurement.

[0004] One aspect of the present invention provides a miniaturized three-axis high temperature resistant optical fiber MEMS vibration sensor, including a vibration sensitive structure, x- and y-axis light emitting optical fibers, x- and y-axis collimation cover plates, z-axis light emitting optical fibers, z-axis collimation cover plates, and a collimation tube;

[0005] The vibration sensitive structure comprises an integrated frame having three mutually perpendicular surfaces and three groups of beam-mass block structures respectively embedded in the three surfaces of the integrated frame, wherein the three surfaces are an x-axis plane, a y-axis plane and a z-axis plane, respectively, and each group of beam-mass block structures comprises a mass block and one or more pairs of beams, wherein the beams are symmetrically distributed around the mass block and connect the mass block with the integrated frame, wherein the thickness of the mass block does not exceed the thickness of the integrated frame, and the thickness of the beams does not exceed the thickness of the mass block;

[0006] The x- and y-axis light-emitting optical fibers are cut at the ends along a 45° direction to form an inclined end face, the ends of the inclined end faces are ground to form a grinding plane, and an FP cavity is formed between the grinding plane and the surface of the mass block; the x- and y-axis collimation cover plates are provided with grooves, the x- and y-axis light-emitting optical fibers are placed at the bottom of the grooves, the optical fiber light-emitting directions are the directions of the grooved planes of the x- and y-axis collimation cover plates, and the optical fiber light-emitting positions face the surface of the mass block; the x- and y-axis collimation cover plates are bonded to the x-axis plane and the y-axis plane of the integrated frame, respectively, and can measure the vibrations of the x- and y-axes;

[0007] The z-axis light-emitting optical fiber is a 90° cut optical fiber, and an FP cavity is formed between the 90° cut end face and the surface of the mass block; a circular hole is opened in the center of the z-axis collimation cover plate, and the collimation tube is cylindrical and fixed on the collimation cover plate, and a through hole is opened in the center, and the z-axis light-emitting optical fiber passes through the circular hole and the through hole to penetrate the collimation tube and the z-axis collimation cover plate respectively; the z-axis collimation cover plate is bonded to the z-axis plane of the integrated frame, and can measure the vibration of the z-axis.

[0008] Preferably, the beam-mass block structure and the integrated frame are made of silicon and are formed by MEMS processing.

[0009] Preferably, the x- and y-axis light-emitting optical fibers have a core, a cladding and a coating, and the polished portion of the polished plane exceeds the thickness of the coating but does not exceed the center line of the x- and y-axis light-emitting optical fibers.

[0010] Preferably, the width of the groove of the x-axis and y-axis alignment cover plates is the outer diameter of the optical fiber, and the depth of the groove is not less than the diameter of the optical fiber.

[0011] Preferably, the x-axis and y-axis light-emitting optical fibers are fixed to the bottom of the groove by using high-temperature glue or laser welding.

[0012] Preferably, the x-axis and y-axis collimation cover plates, the z-axis collimation cover plate and the collimation tube are all made of high borosilicate glass.

[0013] Preferably, the collimating tube and the z-axis collimating cover plate, and the z-axis light-emitting optical fiber and the collimating tube are fixed by high-temperature glue or laser welding.

[0014] Preferably, one end of the collimator tube that penetrates into the z-axis light-emitting optical fiber is provided with a flare.

[0015] The miniaturized three-axis high-temperature-resistant optical fiber MEMS vibration sensor according to the above aspects of the present invention can achieve miniaturization, high-temperature resistance and three-axis vibration measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0017] Figure 1 It is a schematic diagram of the overall structure of a miniaturized three-axis high temperature resistant optical fiber MEMS vibration sensor according to an embodiment of the present invention;

[0018] Figure 2 is a schematic structural diagram of a vibration sensitive structure according to an embodiment of the present invention;

[0019] Figure 3 It is a schematic diagram of an embodiment of the present invention in which the x-axis and y-axis light-emitting optical fibers are folded 90 degrees to emit light and form an FP cavity with the surface of a mass block;

[0020] Figure 4 is a schematic diagram of an x- and y-axis alignment cover plate according to an embodiment of the present invention;

[0021] Figure 5 It is a schematic diagram of the cooperation between the x-axis and y-axis light-emitting optical fibers and the x-axis and y-axis collimation cover plates according to one embodiment of the present invention;

[0022] Figure 6 It is a schematic diagram of an embodiment of the present invention in which the x-axis and y-axis light-emitting optical fibers cooperate with the x-axis and y-axis collimating cover plates to form an FP cavity with the surface of the mass block;

[0023] Figure 7 is a schematic diagram of an x-axis and y-axis vibration measurement sensor according to an embodiment of the present invention;

[0024] Figure 8 It is a schematic diagram of a FP cavity formed by a 90° cut end face of a z-axis light-emitting optical fiber and a surface of a mass block according to an embodiment of the present invention;

[0025] Fig. 9 is a schematic diagram of a z-axis collimation cover plate according to an embodiment of the present invention;

[0026] Fig.10 is a schematic diagram of a collimator according to an embodiment of the present invention;

[0027] Fig.11 is a schematic diagram of bonding a z-axis alignment cover plate to an integrated frame according to an embodiment of the present invention;

[0028] Fig.12 is a schematic diagram of fixing a collimator tube and a z-axis collimator cover plate according to an embodiment of the present invention;

[0029] Fig.13It is a schematic diagram of fixing the z-axis light-emitting optical fiber and the collimating tube according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] One embodiment of the present invention provides a miniaturized three-axis high temperature resistant optical fiber MEMS vibration sensor. Figure 1 As shown, the vibration sensor of the embodiment of the present invention includes a vibration sensitive structure 1, x- and y-axis light-emitting optical fibers 2, x- and y-axis collimating cover plates 3, z-axis light-emitting optical fibers 4, z-axis collimating cover plates 5 and a collimating tube 6.

[0032] like Figure 2 As shown, the x, y, and z axes of the vibration sensitive structure 1 are perpendicular to each other, including three groups of beam-mass block structures, which are respectively embedded in the hollow integrated frame 8. The integrated frame 8 has three perpendicular planes: the x-axis plane (yz plane), the y-axis plane (xz plane), and the z-axis plane (xy plane). The three groups of beam-mass block structures are respectively embedded in the three planes. Each group of beam-mass block structures includes at least one mass block 9 and one or more pairs of beams 10. The beams 10 are symmetrically distributed around the mass block 9 and connect the mass block 9 with the integrated frame 8. The thickness of the mass block 9 does not exceed the thickness of the frame in which it is located, and the thickness of the beam 10 does not exceed the thickness of the mass block 9. The material of the beam-mass block structure and the integrated frame 8 is silicon, and the whole is formed by MEMS method. The outer dimensions of the frame 8 are, for example, 7mm×7mm×7mm, and the thickness of the integrated frame 8 is, for example, 1mm.

[0033] In order to realize the miniaturization of the vibration sensor, the x- and y-axis light-emitting optical fibers 2 are 90° folded light-emitting optical fibers, shortening the optical fiber lead-out length in the x and y directions of the vibration sensor, and leading the three vibration signal transmission optical fibers from the z direction. The x- and y-axis light-emitting optical fibers 2 have a core, a cladding, and a coating layer, and the outer diameter is, for example, 155 microns. Figure 3As shown, the optical fiber is cut at a 45° angle at the end to form an inclined end face 11, and a section of a polished plane 12 is ground at the end. The polished portion exceeds the coating thickness but does not exceed the center line of the optical fiber. The incident light is reflected at the 45° inclined end face 11, emitted through the polished plane 12 and propagates in the air until it is reflected by the surface of the mass block and is incident again through the polished plane 12 into the optical fiber. An FP cavity is formed between the polished plane 12 of the x- and y-axis light-emitting optical fiber 2 and the surface of the mass block. When external vibration causes the FP cavity structure to generate forced vibration, the vibration value can be calculated by detecting the change in the cavity length between the polished plane 12 and the surface of the mass block.

[0034] In order to constrain the spatial position of the optical fiber during vibration, the x- and y-axis alignment cover plates 3 of the embodiment of the present invention are provided with grooves. The outer dimensions of the alignment cover plates are consistent with the projection dimensions of the integrated frame 8 in a certain mass block plane, and the thickness is, for example, 1 mm. The groove width is 155 microns of the outer diameter of the optical fiber, and the groove depth is not less than the optical fiber diameter, for example, 160 microns. The material of the x- and y-axis alignment cover plates 3 is high borosilicate glass, such as Figure 4 shown.

[0035] The x- and y-axis light-emitting optical fibers 2 are placed at the bottom of the groove, and the spatial position of the optical fibers is constrained in two aspects: first, the light-emitting direction of the optical fibers is the direction of the slotted plane 13 of the x- and y-axis collimating cover plate 3, such as Figure 5 As shown; the second is that the optical fiber light output position is facing the surface of the mass block, such as Figure 6 As shown. Use high temperature glue or laser welding to fix the optical fiber to ensure that there is no relative displacement between the optical fiber and the collimation cover. The initial cavity length of the FP cavity can be adjusted by increasing or decreasing the thickness of the mass block and the depth of the collimation cover groove.

[0036] Two sets of x-axis and y-axis collimating cover plates 3 with x-axis and y-axis optical fibers 2 are bonded to the integrated frames 8 of the xz plane and the yz plane, respectively, to form x-axis and y-axis vibration measurement sensors, which can measure the vibration of the x-axis and y-axis. Figure 7 shown.

[0037] In the embodiment of the present invention, a 90° cut optical fiber is used as the z-axis light-emitting optical fiber 4, and an FP cavity is formed between the 90° cut end face and the surface of the mass block. When external vibration causes the FP cavity structure to generate forced vibration, the vibration value can be calculated by detecting the change in the cavity length between the 90° cut end face and the surface of the mass block, such as Figure 8 shown.

[0038] In order to ensure the stability of the structure of the z-axis light-emitting optical fiber 4, the z-axis collimation cover plate 5 and the collimation tube 6 of the embodiment of the present invention are made of high borosilicate glass. A circular hole is opened in the center of the z-axis collimation cover plate 5, and the diameter of the circular hole is larger than the diameter of the optical fiber. Fig. 9The collimator tube 6 is cylindrical, with a through hole in the center, and the aperture is, for example, 160 microns; in order to facilitate the insertion of the optical fiber, the z-axis collimator cover plate 5 has a flared opening at one end where the optical fiber is inserted, as shown in FIG. Fig.10 shown.

[0039] The z-axis alignment cover plate 5 is bonded to the integrated frame 8 of the xy plane in the z-axis direction, such as Fig.11 The collimator tube and the z-axis collimator cover plate 5 are fixed by high temperature glue or laser welding, as shown. Fig.12 As shown. The z-axis optical fiber 4 with a 90° cut end face is inserted into the collimator 6 to form an FP cavity with the mass block in the z-axis direction. The z-axis optical fiber 4 is fixed to the collimator 6 by high-temperature glue or laser welding to form a z-axis vibration measurement sensor, which can measure the vibration of the z-axis. Fig.13 As shown. The final formation Figure 1 The vibration sensor shown has an outer dimension of, for example, 8 mm×8 mm×7 mm.

[0040] To summarize, the vibration sensor of the embodiment of the present invention adopts a three-axis mutually perpendicular MEMS vibration sensitive structure and an optical fiber lead-out technology based on a 90° turning optical path, which can reduce the size of the sensitive structure and the size of the lateral optical fiber lead-out, while realizing three-axis vibration measurement. It also adopts packaging methods such as bonding and high-temperature glue, and has the advantage of high temperature resistance, thereby realizing miniaturized three-axis high-temperature resistant vibration measurement.

[0041] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A miniaturized three-axis high temperature resistant optical fiber MEMS vibration sensor, characterized in that: It includes a vibration sensitive structure, x- and y-axis light-emitting optical fibers, x- and y-axis collimation cover plates, z-axis light-emitting optical fibers, z-axis collimation cover plates, and a collimation tube; The vibration sensitive structure comprises an integrated frame having three mutually perpendicular surfaces and three groups of beam-mass block structures respectively embedded in the three surfaces of the integrated frame, wherein the three surfaces are an x-axis plane, a y-axis plane and a z-axis plane, respectively, and each group of beam-mass block structures comprises a mass block and one or more pairs of beams, wherein the beams are symmetrically distributed around the mass block and connect the mass block with the integrated frame, wherein the thickness of the mass block does not exceed the thickness of the integrated frame, and the thickness of the beams does not exceed the thickness of the mass block; The x- and y-axis light-emitting optical fibers are cut at the ends along a 45° direction to form an inclined end face, the ends of the inclined end faces are ground to form a grinding plane, and an FP cavity is formed between the grinding plane and the surface of the mass block; the x- and y-axis collimation cover plates are provided with grooves, the x- and y-axis light-emitting optical fibers are placed at the bottom of the grooves, the optical fiber light-emitting directions are the directions of the grooved planes of the x- and y-axis collimation cover plates, and the optical fiber light-emitting positions face the surface of the mass block; the x- and y-axis collimation cover plates are bonded to the x-axis plane and the y-axis plane of the integrated frame, respectively, and can measure the vibrations of the x- and y-axes; The z-axis light-emitting optical fiber is a 90° cut optical fiber, and an FP cavity is formed between the 90° cut end face and the surface of the mass block; a circular hole is opened in the center of the z-axis collimation cover plate, and the collimation tube is cylindrical and fixed on the collimation cover plate, and a through hole is opened in the center, and the z-axis light-emitting optical fiber passes through the circular hole and the through hole to penetrate the collimation tube and the z-axis collimation cover plate respectively; the z-axis collimation cover plate is bonded to the z-axis plane of the integrated frame, and can measure the vibration of the z-axis.

2. The vibration sensor according to claim 1, characterized in that The beam-mass block structure and the integrated frame are made of silicon and are formed by MEMS processing.

3. The vibration sensor according to claim 1 or 2, characterized in that: The x- and y-axis light-emitting optical fibers have a core, a cladding and a coating layer, and the polished portion of the polished plane exceeds the thickness of the coating layer but does not exceed the center line of the x- and y-axis light-emitting optical fibers.

4. The vibration sensor according to claim 1 or 2, characterized in that: The width of the groove of the x-axis and y-axis alignment cover plates is the outer diameter of the optical fiber, and the depth of the groove is not less than the diameter of the optical fiber.

5. The vibration sensor according to claim 1 or 2, characterized in that: The x-axis and y-axis light-emitting optical fibers are fixed to the bottom of the groove by using high-temperature glue or laser welding.

6. The vibration sensor according to claim 1 or 2, characterized in that: The x-axis and y-axis collimation cover plates, the z-axis collimation cover plate and the collimation tube are all made of high borosilicate glass.

7. The vibration sensor according to claim 1 or 2, characterized in that: The collimating tube and the z-axis collimating cover plate, and the z-axis light-emitting optical fiber and the collimating tube are fixed by high-temperature glue or laser welding.

8. The vibration sensor according to claim 1 or 2, characterized in that: One end of the collimator tube that penetrates into the z-axis light-emitting optical fiber is provided with a horn mouth.

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