CN113340491A

CN113340491A - High-consistency preparation method of optical fiber Fabry-Perot pressure sensor and sensitive unit thereof

Info

Publication number: CN113340491A
Application number: CN202110769703.0A
Authority: CN
Inventors: 贾平岗; 熊继军; 李加顺; 刘佳; 安国文; 梁庭
Original assignee: North University of China
Current assignee: North University of China
Priority date: 2021-07-07
Filing date: 2021-07-07
Publication date: 2021-09-03
Anticipated expiration: 2041-07-07
Also published as: CN113340491B

Abstract

The present disclosure describes a high consistency manufacturing method of an optical fiber Fabry-Perot pressure sensor and a sensitive unit thereof, which comprises the following steps: preparing a first quartz plate, a second quartz plate and a third quartz plate; polishing the upper surface of the first quartz plate, polishing the upper surface and the lower surface of the second quartz plate, and polishing the upper surface of the third quartz plate; manufacturing a plurality of grooves on the upper surface of the first quartz plate or the upper surface of the second quartz plate in a preset distribution mode; manufacturing a plurality of through holes on the third quartz plate in a preset distribution mode; combining the upper surface of the first quartz plate with the upper surface of the second quartz plate in a manner of covering the plurality of grooves, and combining the upper surface of the third quartz plate with the lower surface of the second quartz plate to form a stacked body in which each groove and each through hole are coaxial respectively; and cutting the plurality of grooves to obtain a plurality of sensitive units. According to the present disclosure, the consistency of the sensitive units of the fiber Fabry-Perot pressure sensor can be improved.

Description

High-consistency preparation method of optical fiber Fabry-Perot pressure sensor and sensitive unit thereof

Technical Field

The disclosure relates to a high-consistency preparation method of an optical fiber Fabry-Perot pressure sensor and a sensitive unit thereof.

Background

In recent years, with rapid development in the fields of aerospace, chemical engineering, energy and the like, higher and higher requirements are made on the reliability of a pressure sensor in a high-temperature environment, and the traditional piezoresistive or piezoelectric pressure sensor is difficult to be applied to the fields for high-precision pressure measurement due to the problems that a manufacturing material cannot resist high temperature, the heat conduction of a signal line has adverse effects on a demodulation system and the like.

An optical fiber type pressure sensor, such as an optical fiber Fabry-Perot type pressure sensor, generally senses pressure by a sensing unit based on an optical principle, and has the advantages of small volume, high sensitivity, corrosion resistance, electromagnetic interference resistance and the like. The sensing unit can be made of high-temperature-resistant materials, and the high temperature is not easy to influence the application of the optical principle, so that the optical fiber Fabry-Perot pressure sensor is suitable for pressure measurement in the high-temperature environment. In recent years, techniques for manufacturing the optical fiber fabry-perot pressure sensor mainly include MEMS techniques, chemical etching techniques, arc discharge techniques, laser processing techniques, and the like. However, the consistency of the sensors manufactured by using the chemical etching technology, the arc discharge technology and the laser processing technology is relatively poor, for example, the consistency of each sensitive unit is low due to the inconsistency of the thickness and the effective radius of the sensitive membrane of different sensitive units, and the low-cost mass manufacturing of the sensors is difficult to realize.

On the contrary, the sensor manufactured by using the MEMS technology has the advantages of high consistency of sensitive units and mass production. At present, a pressure sensor is reported in China, which utilizes Pyrex glass discs and silicon wafers to realize batch manufacturing of optical fiber Fabry-Perot pressure sensors, and the pressure sensor can measure pressure in a high-temperature environment of 350 ℃, however, due to the limitation of the characteristics of the materials, the pressure sensor is difficult to realize pressure testing in a higher-temperature environment. Moreover, because two materials with different thermal expansion coefficients are used for manufacturing the sensor, when the sensor works in a high-temperature environment, the use performance of the sensor is affected due to the mismatch of the thermal expansion coefficients of the different materials, which is also one of the reasons for limiting the application of the sensor at high temperature. In addition, in the connection method of the optical fiber and the sensing unit, a common method at present is to use ultraviolet epoxy resin or a high-temperature-resistant adhesive, and introduce a bonding material into the sensor which needs to work in a high-temperature environment will further influence the stability and the service life of the sensor at high temperature.

The softening point of the fused quartz glass material reaches about 1730 ℃, and the fused quartz glass material is resistant to acid and alkali corrosion, and compared with the materials commonly used for manufacturing the optical fiber Fabry-Perot pressure sensor at present, such as metal, Pyrex glass, silicon, sapphire, SiC and the like, the fused quartz glass material has a lower thermal expansion coefficient, so that the fused quartz glass material becomes a good material for manufacturing the high-temperature pressure sensor. In the invention, a batch-manufacturable all-quartz optical fiber Fabry-Perot pressure sensor is manufactured and verified by using a high-temperature hot-pressing bonding technology and a micromachining technology, and CO is used₂The laser welding technology realizes the non-glue sealing integration of the sensor full-quartz sensitive unit and the signal transmission optical fiber, so that the sensor can stably work in a high-temperature environment.

Disclosure of Invention

The present disclosure has been made in view of the above-mentioned state of the art, and an object thereof is to provide a highly uniform manufacturing method of a sensing cell of an optical fiber fabry-perot pressure sensor capable of improving uniformity of the optical fiber fabry-perot pressure sensor.

To this end, the first aspect of the present disclosure provides a high-consistency preparation method for a sensing unit of a fiber-optic fabry-perot pressure sensor, comprising the following steps: preparing a first quartz plate having opposite upper and lower surfaces, a second quartz plate having opposite upper and lower surfaces, and a third quartz plate having opposite upper and lower surfaces; polishing the upper surface of the first quartz plate, polishing the upper surface and the lower surface of the second quartz plate, and polishing the upper surface of the third quartz plate; manufacturing a plurality of grooves on the upper surface of the first quartz plate or the upper surface of the second quartz plate in a preset distribution mode; manufacturing a plurality of through holes on the third quartz plate in the preset distribution mode; bonding the upper surface of the first quartz plate to the upper surface of the second quartz plate in a manner of covering the plurality of grooves, and bonding the upper surface of the third quartz plate to the lower surface of the second quartz plate to form a laminated body in which each groove and each through hole are coaxial, respectively; and cutting the plurality of grooves to obtain a plurality of sensitive units.

In the high-consistency preparation method according to the first aspect of the present disclosure, the material consistency of each sensitive unit can be improved by processing the first quartz plate, the second quartz plate and the third quartz plate to obtain a plurality of sensitive units; in addition, by bonding the first quartz plate and the second quartz plate in a manner of covering the plurality of grooves, and bonding the third quartz plate and the second quartz plate to form a laminated body, and cutting the plurality of grooves of the laminated body to obtain the plurality of sensitive cells, the uniformity of the sensitive membrane of each sensitive cell can be improved. Therefore, the consistency of the sensitive units can be improved, and the consistency of the optical fiber Fabry-Perot pressure sensor can be improved.

In addition, in the high-uniformity manufacturing method according to the first aspect of the present disclosure, optionally, the predetermined distribution pattern includes at least a wheel base between the grooves. In this case, the plurality of grooves and the plurality of through holes are made based on the same predetermined distribution pattern, whereby it can be facilitated to arrange the respective grooves coaxially with the respective through holes.

In addition, in the high uniformity manufacturing method according to the first aspect of the present disclosure, optionally, a boss coaxial with each through hole is formed on a lower surface of the third quartz plate of the stacked body at a position corresponding to the through hole, the boss is cylindrical, and a diameter of the boss is less than 2.5 mm. In this case, the soldering of the optical fiber to the sensitive unit can be facilitated by the boss.

In addition, in the high-uniformity production method according to the first aspect of the present disclosure, an air hole that communicates with the groove via the first quartz piece may be optionally formed in the laminated body. In this case, the air pressure inside and outside the cavity is balanced by the plurality of air holes, thereby providing a sensing unit suitable for sensing the sound pressure.

In addition, in the high-uniformity production method according to the first aspect of the present disclosure, optionally, the air holes have an L shape. Therefore, the influence of the air holes on the deformation of the second diaphragm can be reduced.

In addition, in the high-uniformity production method according to the first aspect of the present disclosure, optionally, the number of the air holes is plural, and the plural air holes are uniformly arranged around the axis of the through hole. In this case, when the sound pressure is sensed, it can be advantageous to reduce the influence of the air pressure.

The second aspect of the present disclosure provides a fiber-optic fabry-perot pressure sensor, comprising a sensing unit and an optical fiber, the sensing unit comprises a first diaphragm, a second diaphragm and a third diaphragm which are sequentially stacked, a micro-cavity and a first reflecting surface and a second reflecting surface which are respectively positioned at two opposite sides of the micro-cavity and are parallel to each other are formed between the first diaphragm and the second diaphragm, a through hole coaxial with the micro-cavity and not communicated with the micro-cavity is formed on the third diaphragm, the size of the optical fiber is matched with that of the through hole and the optical fiber is embedded in the through hole, the axis of the optical fiber is orthogonal to the first reflecting surface and the second reflecting surface, light entering the microcavity via the optical fiber can be reflected between the first and second reflective surfaces, wherein the sensitive unit is prepared according to the high-consistency preparation method of the first aspect of the disclosure. In this case, a plurality of sensing units are prepared and a plurality of optical fiber fabry-perot pressure sensors are further prepared by the high-uniformity preparation method according to the first aspect of the present disclosure, whereby the uniformity of the optical fiber fabry-perot pressure sensors can be improved.

In the optical fiber fabry-perot pressure sensor according to the second aspect of the present disclosure, the optical fiber may include a bare fiber and a glass tube having a hollow portion, the glass tube having a size corresponding to a size of the through hole and being fitted in the through hole, the bare fiber having a size corresponding to a size of the hollow portion and being fitted in the hollow portion, an axis of the hollow portion being orthogonal to the first and second reflection surfaces and an end surface of one end of the hollow portion in which the bare fiber is fitted, the first and second reflection surfaces being parallel to each other. In this case, the welding of the optical fiber to the sensitive unit can be facilitated by a glass tube.

In the optical fiber fabry-perot pressure sensor according to the second aspect of the present disclosure, a collimating element arranged to collimate light may be provided on an end surface of one end of the optical fiber fitted in the hollow portion.

In the optical fiber fabry-perot pressure sensor according to the second aspect of the present disclosure, the first diaphragm may have an air hole communicating with the microcavity. In this case, the air pressure inside and outside the cavity is balanced by the air hole, whereby the optical fiber fabry-perot pressure sensor suitable for sensing the sound pressure can be provided.

According to the high-consistency preparation method for the sensing unit of the optical fiber Fabry-Perot pressure sensor, the consistency of the sensing unit of the optical fiber Fabry-Perot pressure sensor can be improved, and therefore the consistency of the optical fiber Fabry-Perot pressure sensor can be improved.

Drawings

The disclosure will now be explained in further detail by way of example only with reference to the accompanying drawings, in which:

fig. 1 is a schematic flow chart diagram illustrating a manufacturing method according to an embodiment of the present disclosure.

Fig. 2 is a schematic diagram showing a first quartz plate, a second quartz plate, and a third quartz plate according to an embodiment of the present disclosure.

Fig. 3 is a schematic diagram illustrating the fabrication of a plurality of grooves and positioning holes in a second quartz plate according to an embodiment of the present disclosure.

Fig. 4 is a schematic diagram illustrating the fabrication of a plurality of through holes and positioning holes in a third quartz plate according to the embodiment of the present disclosure.

Fig. 5 is a schematic diagram illustrating a laminate according to an embodiment of the present disclosure.

Fig. 6 is a schematic view showing the production of a plurality of bosses in a laminate according to the embodiment of the present disclosure.

Fig. 7 is a schematic perspective view illustrating a sensing unit according to an embodiment of the present disclosure.

Fig. 8 is a schematic perspective view showing a first example of a pressure sensor according to an embodiment of the present disclosure.

Fig. 9 is a schematic perspective view showing a second example of the pressure sensor according to the embodiment of the present disclosure.

Fig. 10 is a schematic sectional view along AA' of fig. 9.

Fig. 11 is a schematic diagram illustrating a third example of a pressure sensor of an embodiment of the present disclosure.

Fig. 12 is a schematic diagram illustrating a fourth example of a pressure sensor of an embodiment of the present disclosure.

Detailed Description

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals, and redundant description thereof is omitted. The drawings are schematic and the ratio of the dimensions of the components and the shapes of the components may be different from the actual ones.

It is noted that the terms "comprises," "comprising," and "having," and any variations thereof, in this disclosure, for example, a process, method, system, article, or apparatus that comprises or has a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include or have other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In addition, the headings and the like referred to in the following description of the present disclosure are not intended to limit the content or scope of the present disclosure, but merely serve as a reminder for reading. Such a subtitle should neither be understood as a content for segmenting an article, nor should the content under the subtitle be limited to only the scope of the subtitle.

Embodiments of the present disclosure relate to a method for high-consistency fabrication of a sensing unit of a fiber Fabry-Perot pressure sensor. In the present embodiment, the optical fiber fabry-perot pressure sensor may be simply referred to as a pressure sensor, and the high-uniformity production method may also be referred to as a batch production method or simply a production method. By the preparation method of the embodiment, the consistency of the sensitive units of the pressure sensor can be improved, so that the consistency of the pressure sensor can be improved.

Fig. 1 is a schematic flow chart diagram illustrating a manufacturing method according to an embodiment of the present disclosure. Fig. 2 is a schematic diagram illustrating a first quartz plate 100, a second quartz plate 200, and a third quartz plate 300 according to an embodiment of the present disclosure. Fig. 3 is a schematic diagram illustrating the fabrication of a plurality of grooves and positioning holes in a second quartz plate 200 according to an embodiment of the present disclosure. Fig. 4 is a schematic diagram illustrating the fabrication of a plurality of through holes and positioning holes in third quartz plate 300 according to the embodiment of the present disclosure. Fig. 5 is a schematic diagram illustrating a laminate 400 according to an embodiment of the present disclosure.

Fig. 6 is a schematic diagram illustrating the production of a plurality of bosses in the laminate 400 according to the embodiment of the present disclosure. Fig. 7 is a schematic perspective view illustrating a sensing unit 10 according to an embodiment of the present disclosure. Fig. 8 is a schematic perspective view showing a first example of the pressure sensor 1 according to the embodiment of the present disclosure. Fig. 9 is a schematic perspective view showing a second example of the pressure sensor 1 according to the embodiment of the present disclosure. Fig. 10 is a schematic sectional view along AA' of fig. 9.

In the present embodiment, the pressure sensor 1 may include a sensing unit 10 and an optical assembly 20 (see fig. 8 and 9) connected to the sensing unit 10. The sensing unit 10 can sense the pressure, and the optical assembly 20 and the sensing unit 10 can cooperate to obtain a sensing signal of the pressure. In some examples, the optical assembly 20 may be connected with a demodulation device (not shown) for demodulating the sensing signal and may transmit the sensing signal to the demodulation device, which may demodulate the sensing signal to obtain a measurement of the pressure.

In this embodiment, the fabry-perot cavity is an optical resonant cavity composed of two light guide surfaces that are oppositely arranged, parallel to each other and have a predetermined distance therebetween, and light can be reflected between the two light guide surfaces of the fabry-perot cavity to provide optical feedback. In the Fabry-Perot cavity, the light feedback when light is reflected between the two light guide surfaces has a corresponding relation with the distance between the two light guide surfaces.

In some examples, the sensing unit 10 may include a first diaphragm 11, a second diaphragm 12, and a third diaphragm 13 (see fig. 7) which are sequentially stacked. In some examples, the first diaphragm 11 and the second diaphragm 12 may be formed with a cavity 101 therebetween, and the third diaphragm 13 may have a through hole 102 (see fig. 7) communicating with the cavity 101. In addition, in some examples, the surface of the first diaphragm 11 adjacent to the cavity 101 may be polished, the upper and lower surfaces of the second diaphragm 12 may be polished, and the surface of the third diaphragm 13 adjacent to the cavity 101 may be polished.

In some examples, the optical component 20 may be an optical fiber 21 (see fig. 8). In other examples, the optical module 20 may include an optical fiber 21 and a glass tube 22 having a hollow portion, and the optical fiber 21 may be embedded in the hollow portion of the glass tube 22 (see fig. 9).

In some examples, an end of the optical fiber 21 may be cut flat and the end may be placed in the through hole 102 (see fig. 10). In this case, the surface of the first film 11 close to the cavity 101 may be a first light guide surface, the surface of the second film 102 close to the cavity 101 may be a second light guide surface, and the cavity 101, the first light guide surface, and the second light guide surface may form a fabry-perot cavity.

When pressure is measured using the pressure sensor 1 according to the present embodiment, the first diaphragm 11 can be deformed by the pressure, and the distance between the first light guide surface (i.e., the surface of the first diaphragm 11 close to the cavity 101) and the second light guide surface (i.e., the surface of the second diaphragm 12 close to the cavity 101) can be changed, thereby changing the optical feedback when light is reflected between the first light guide surface and the second light guide surface. The demodulation device may obtain the distance between the first light guide surface and the second light guide surface based on the changed optical feedback to obtain the deformation of the first diaphragm 11, so as to obtain the measurement result of the pressure sensor 1 on the pressure.

In some examples, the cavity 101 may be cylindrical, elliptical cylindrical, or prismatic, such as a quadrangular prism, among others. In some examples, the through-hole 102 may be a cylindrical through-hole. In some examples, the boss 103 (described later) may have a cylindrical, elliptical, or prismatic shape, such as a quadrangular prism, or the like. Additionally, in some examples, cavity 101, through-hole 102, and boss 103 may be coaxial.

In some examples, in the sensing unit 10, the through hole 102 may be perpendicular to the surface of the second diaphragm 12 near the cavity 101. This can collimate the optical fiber 21, and contributes to coupling the incident light beam emitted from the optical fiber 21 into the first light guide surface and the second light guide surface of the pressure sensor 1, and better coupling the light beam reflected from the first light guide surface and the second light guide surface of the pressure sensor 10 into the optical fiber 21.

In some examples, the through-hole 102 may have an inner diameter that matches an outer diameter of the glass tube 22, and the glass tube 22 may have an inner diameter that matches an outer diameter of the optical fiber 21. The optical fiber 21 may be placed in the glass tube 22 and fixed in the glass tube 22 by, for example, high temperature welding, and then the glass tube 22 may be placed in the through hole 102, and the flattened end face of the optical fiber 21 is attached to the surface of the second membrane 12 away from the cavity 101 and fixed to the boss 103 by, for example, high temperature welding (see fig. 10). In this case, by connecting the optical fiber 21 to the sensing unit 10 using the glass tube 22, the optical fiber 21 can be collimated, and the incident light beam emitted from the optical fiber 21 can be better coupled into the first light guide surface and the second light guide surface of the pressure sensor 1, and the light beam reflected from the first light guide surface and the second light guide surface of the pressure sensor 1 can be better coupled into the optical fiber.

In some examples, the end face at the flattened end of the optical fiber 21 may also be provided with a collimating element (not shown). The collimating element may collimate light exiting the optical fiber. In some examples, the flattened end of the optical fiber 21 may be embedded in the hollow of the glass tube 22 or in the through hole 102.

The present disclosure may provide a pressure sensor 1, the pressure sensor 1 may include a sensing unit 10, a glass tube 22 having a hollow portion, and an optical fiber 21, the sensing unit 10 may include a first inner surface (i.e., a surface of the first diaphragm 11 close to the cavity 101), a second inner surface opposite to the first inner surface (i.e., a surface of the second diaphragm 12 close to the cavity 101), the cavity 101 formed between the first inner surface and the second inner surface, and a third diaphragm 13 having a through hole 102, a size of the glass tube 22 may match a size of the through hole 102 and the glass tube 22 may be embedded in the through hole 102, a size of the optical fiber 21 may match a size of the hollow portion of the glass tube 22 and the optical fiber 21 may be embedded in the hollow portion, an axis of the hollow portion may be orthogonal to the second light guide surface and an end surface of one end of the optical fiber 21 embedded in the hollow portion may be attached to a surface of the second diaphragm 12 away from the cavity 101, light entering the cavity via the optical fiber 21 can be reflected between the first light guiding surface and the second light guiding surface. In this case, a plurality of sensing units 10 are prepared by the high-consistency preparation method according to the present disclosure, the diaphragm thickness and the effective sensing diameter of the sensing diaphragm layer of each sensing unit are the same, the length of the fabry-perot cavity (i.e., the distance between the first light guide surface and the second light guide surface) of each sensing unit tends to be consistent, and a plurality of optical fiber fabry-perot pressure sensors 1 are further prepared, so that the consistency of the optical fiber fabry-perot pressure sensors 1 can be improved.

In some examples, glass tube 22 may be bonded to sensing unit 10 via high temperature welding, such as laser welding. Additionally, in some examples, the optical fiber 21 may be bonded to the glass tube 22 via a high temperature fusion splice, such as laser welding.

As described above, in the pressure sensor 1, the first diaphragm 11 is deformed by sensing pressure, so that the distance between the two light guide surfaces in the fabry-perot cavity can be changed, and the distance between the two light guide surfaces can be obtained by light feedback when light is reflected between the two light guide surfaces. Thereby, the deformation of the first diaphragm 11 due to the pressure can be obtained, and the measurement result of the pressure can be obtained.

From this, it is understood that the pressure sensor 1 improves the uniformity of the sensing cells 10 in the pressure sensor 1, and contributes to the improvement of the uniformity of the pressure sensor 1.

In the present embodiment, as shown in fig. 1, the preparation method may include the steps of: preparing a first quartz piece 100, a second quartz piece 200 and a third quartz piece 300 (step S100); manufacturing a plurality of grooves 201 and positioning holes 202 on a second quartz plate 200 (step S200); forming a plurality of through holes 301 and positioning holes 302 in the third quartz plate 300 (step S300); combining the first quartz plate 100, the third quartz plate 300 and the second quartz plate 200 to form a laminated body 400 (described later) (step S400); fabricating a plurality of bosses 401 in the laminate 400 (step S500); the laminated body 400 is cut (step S600).

In step S100 of the present embodiment, a first quartz plate 100 having opposite upper and lower surfaces is prepared, a second quartz plate 200 having opposite upper and lower surfaces is prepared, and a third quartz plate 300 having opposite upper and lower surfaces is prepared (see fig. 2). It should be understood that terms such as "upper surface", "lower surface", and the like may be used to distinguish between different regions and should not be considered limiting.

In some examples, upper surface 0 of first quartz wafer 100 may be polished. In some examples, the upper and lower surfaces of the second quartz plate 200 may be polished, and the upper surface of the third quartz plate 300 may be polished. In this case, the bonding between the upper surface of the first quartz plate 100 and the upper surface of the second quartz plate 200 can be facilitated by polishing the upper surface of the first quartz plate 100 and the upper surface of the second quartz plate 200, and the bonding between the lower surface of the second quartz plate 200 and the upper surface of the third quartz plate 300 can be facilitated by polishing the lower surface of the second quartz plate 200 and the upper surface of the third quartz plate 300, so that the tightly bonded stacked body 400 can be formed.

In some examples, the lower surface of the third quartz plate 300 may be polished. In some examples, the lower surface of first quartz sheet 100 may be roughened. Thereby, the influence of the lower surface of the first quartz plate 100 on the light reflection can be reduced.

In some examples, the thickness of second quartz plate 200 may be greater than the thickness of first quartz plate 100, and the thickness of third quartz plate may be greater than the thickness of second quartz plate. In some examples, first quartz plate 100, second quartz plate 200, and third quartz plate 300 may be circular quartz plates (see fig. 2). In some examples, first quartz plate 100, second quartz plate 200, or third quartz plate 300 may be a 2 inch wafer, a 4 inch wafer, or a 6 inch wafer. In some examples, the diameter of second quartz plate 200 and the diameter of first quartz plate 100 may be equal. In some examples, the diameter of second quartz plate 200 may be slightly smaller than the diameter of first quartz plate 100. Thereby, the upper surface of the first quartz plate 100 can cover the upper surface of the second quartz plate 200.

In other examples, the thickness of second quartz plate 200 may also be equal to or less than the thickness of first quartz plate 100. The thickness of the third quartz plate 300 may also be equal to or less than the thickness of the second quartz plate 200.

In some examples, the second quartz plate 200 may be a circular quartz plate of uniform thickness. In some examples, the second quartz plate 200 may have a thickness of 0.1mm to 2 mm. In some examples, the first quartz plate 100 may be a circular quartz plate of uniform thickness. In some examples, the thickness of first quartz plate 100 may be 10 μm to 500 μm. In some examples, the third quartz plate 300 may be a circular quartz plate having a uniform thickness, and the thickness of the third quartz plate 300 may be 0.5 to 2 mm.

As described above, in step S200 of the present embodiment, a plurality of grooves 201 may be formed on the upper surface of the second quartz plate 200 (in the example shown in fig. 3, one of the plurality of grooves 201 is marked). In the embodiment shown in fig. 3, the plurality of grooves may be an array of grooves. In some examples, the grooves in the groove array may be uniformly distributed on the upper surface of the second quartz plate 200. In some examples, the groove array can be fabricated based on a predetermined distribution pattern. The predetermined distribution pattern may include at least a wheel base between the respective grooves, and the like.

In some examples, the location of the locating holes 202 of the second quartz plate 200 may be near the edge of the second quartz plate.

In some examples, the grooves in the groove array may be cylindrical, elliptical cylindrical, or prismatic. In some examples, the grooves in the groove array may preferably be cylindrical. In some examples, the grooves in the groove array may have the same diameter. In other examples, the grooves in the groove array may have different diameters. In some examples, the grooves in the groove array may have the same depth.

In some examples, the grooves in the groove array may have a diameter of 80 μm to 10 mm. In some examples, the depth of the grooves in the groove array may be 3 μm to 100 μm.

In some examples, the wheelbase between adjacent grooves may be 1.5 to 2 times the diameter of each groove. However, the example of the present embodiment is not limited thereto, and in other examples, the wheelbase between adjacent grooves may be 2 to 4 times the diameter of each groove.

In some examples, the grooves in the groove array can be mass-produced on the upper surface of the second quartz plate 200 by a MEMS process, and the grooves in the groove array can have a uniform depth by using a MEMS technology, which is beneficial to improve the uniformity of the sensitive units.

As described above, in step S300 of this embodiment, a plurality of through holes 301 (one of the through holes 301 is marked in the example shown in fig. 3) and positioning holes 302 may be formed on the upper surface of the third quartz plate 300. Specifically, a plurality of through holes and positioning holes may be formed in the upper surface of third quartz plate 300 at positions corresponding to the respective microcavities and positioning holes of the second quartz plate. In the embodiment shown in fig. 4, the plurality of vias may be an array of vias.

In some examples, the vias in the via array may be cylindrical vias or prismatic vias. In some examples, the fabrication of the via array may be based on a predetermined distribution pattern. In this case, the groove array and the via array are made based on the same predetermined distribution pattern, whereby it is possible to facilitate the alignment of each groove with each via.

In some examples, the vias in the via array may have the same aperture. In some examples, the aperture of each through-hole may be smaller than the diameter of each microcavity. In some examples, the aperture of the through-holes in the through-hole array may be 50 μm to 2.4 mm.

In some examples, locating holes 302 of third quartz sheet 300 may be near the edge of third quartz sheet 300.

In some examples, the vias in the array of vias may be made on the upper surface of third quartz wafer 300 by a laser cutting process. For example, through holes having the same diameter may be formed on the upper surface of the first quartz plate 100 by computer numerical control machining (CNC machining).

As described above, in step S400 of the present embodiment, the upper surface of the first quartz plate 100 is bonded to the upper surface of the second quartz plate 200 in such a manner as to cover the groove array, and the upper surface through-hole positioning hole-defining positions of the third quartz plate 300 are bonded to the lower surface of the second quartz plate 200 to form the laminated body 400 (see fig. 5). In the laminated body 400, the positioning holes of the second quartz plate 200 are coaxial with the positioning holes of the third quartz plate 300, and each groove in the groove array of the second quartz plate 200 is respectively coaxial with a through hole at each corresponding position in the through hole array of the third quartz plate 300. It is possible to facilitate the respective grooves to be coaxial with the respective through holes by aligning the positioning holes of the second quartz plate 200 with the positioning holes of the third quartz plate 300.

In some examples, first quartz plate 100, second quartz plate 200, and third quartz plate 300 may be bonded via thermal bonding. In some examples, first quartz wafer 100, second quartz wafer 200, and third quartz wafer 300 may be bonded via high temperature thermocompression bonding or low temperature bonding. In other examples, first quartz plate 100, second quartz plate 200, and third quartz plate 300 may also be bonded via an adhesive.

In some examples, bonding the first quartz plate 100, the second quartz plate 200 and the third quartz plate 300 may include the steps of: cleaning the first quartz plate 100, the second quartz plate 200 and the third quartz plate 300; carrying out hot-pressing pre-bonding on the first quartz plate 100, the second quartz plate 200 and the third quartz plate 300 in a low-temperature environment; and performing high-temperature hot-pressing connection on the first quartz wafer 100, the second quartz wafer 200 and the third quartz wafer 300 in a high-temperature environment.

In some examples, the cleaning may be RCA standard cleaning or megasonic cleaning, or the like. In some examples, the low temperature environment may be 200 to 500 degrees. In some examples, the gas pressure at which the thermocompression pre-bonding is performed may be 1Bar to 50 Bar. In some examples, the processing time for thermocompression prebonding may be 5 to 100 minutes. In some examples, the high temperature environment may be 900 to 1200 degrees. In some examples, the treatment time for high temperature annealing consolidation may be 1 hour to 4 hours.

In some examples, in the stacked body 400, the axes of the grooves in the groove array may be perpendicular to the upper surface of the first quartz plate 100, and the axes of the through holes in the through hole array may be perpendicular to the upper surface of the first quartz plate 100.

As described above, in step S500 of the present embodiment, a plurality of bosses may be formed in the laminate 400. Specifically, a plurality of bosses 401 (one of the plurality of bosses 401 is marked in the embodiment shown in fig. 6) may be formed at positions corresponding to the respective through holes on the lower surface of the third quartz plate 300 of the laminated body 400. In the embodiment shown in fig. 6, the plurality of bosses may be an array of bosses.

In some examples, the bosses in the array of bosses may be cylindrical bosses or prismatic bosses. In some examples, each boss in the array of bosses may be coaxial with each corresponding through-hole in the array of through-holes.

In some examples, the lands in the array of lands may have the same height. In some examples, the height of the lands in the array of lands may be 0.5mm to 1.5 mm.

In some examples, the bosses in the boss array may have the same diameter. In some examples, the diameter of each boss may be less than the diameter of each microcavity. In some examples, the diameter of the lands in the array of lands may be 100 μm to 2.5 mm.

In some examples, in the stacked body 400, a plurality of micro cavities and a plurality of bosses are arranged on the side of the upper surface of the second quartz plate 200 and the side of the lower surface of the third quartz plate 300, and the through holes respectively penetrate the bosses.

Specifically, a groove in the groove array, a through hole in the through hole array and a boss in the boss array are respectively and correspondingly coaxial through a positioning hole and a positioning hole, and the through hole in the through hole array penetrates through the boss in the boss array;

in some examples, the boss array may be fabricated on the lower surface of the third quartz plate 300 by a laser cutting process. For example, the bosses in the boss array having the same height and the same diameter may be fabricated on the lower surface of the third quartz plate 300 by computer numerical control machining (CNC machining).

It should be noted that in some examples, the above-mentioned bosses in the boss array may facilitate the soldering of the optical fiber 21 to the sensing unit 10. In other examples, the boss array may not be formed on the lower surface of the third quartz plate 300 (see fig. 5). In this case, the optical fiber 21 can be soldered directly into the through hole 102 of the sensing unit 10.

As described above, in step S600 of the present embodiment, the laminated body 400 is cut, thereby obtaining a plurality of sensitive cells. The individual sensor heads cut are shown in fig. 7, and in some examples, the predetermined cut diameter is greater than the diameter of each groove and is not greater than the wheelbase between adjacent through-holes.

In the present embodiment, a plurality of micro-cavities having the same diameter and depth are formed in the second quartz plate 200, and the plurality of micro-cavities are covered with the first quartz plate 100 and the lower surface of the second quartz plate 200 is covered with the third quartz plate 300, whereby a plurality of uniform fabry-perot cavities (for example, uniform shape, uniform size, etc.) can be formed. In addition, since the first quartz plate 100 has a uniform thickness, a plurality of sensitive diaphragms can be formed that are respectively matched with the respective cavities and have high uniformity (for example, the diaphragms are uniform in material, shape, and size, and thus are uniform in deformation caused by sensing pressure). In this case, by cutting the laminated body 400 formed by joining the first quartz plate 100, the second quartz plate 200, and the third quartz plate 300, a plurality of sensitive cells 10 having high uniformity can be obtained.

Fig. 11 is a schematic diagram showing a third example of the pressure sensor 1 of the embodiment of the present disclosure. Fig. 12 is a schematic diagram showing a fourth example of the pressure sensor 1 of the embodiment of the present disclosure.

In some examples, an air hole communicating with the cavity 101 may be made on the first diaphragm 11 of the sensing unit 10 (see fig. 11 and 12). In this case, the communication of the cavity through the air hole can reduce the influence of the air pressure on the first diaphragm 11, and the first diaphragm 11 can still sense the sound pressure. Thereby, a sensing unit 10 for sensing a sound pressure can be provided, and accuracy of sensing the sound pressure by the sensing unit 10 can be improved.

In some examples, the number of air holes may be 2 to 12, for example the number of air holes may be 2, 3, 4, 5, 6, 8, 9, 10, or 12. In the embodiment shown in fig. 11 and 12, the plurality of air holes may be a first air hole 11a, a second air hole 11b, a third air hole (not shown), and a fourth air hole (not shown) (see fig. 11 and 12). In some examples, the first, second, third, and

fourth air holes

11a, 11b may be evenly distributed around the axis of the through-hole 102. This can more effectively reduce the influence of the air pressure or the hydraulic pressure on the first diaphragm 11.

In some examples, a plurality of air holes may extend through the first membrane 11. In some examples, the axes of the plurality of air holes may be orthogonal to the first membrane 11 or at a predetermined angle to the first membrane 11. In some examples, the axis of the through-hole 102 may not pass through any of the plurality of air holes.

In other examples, a plurality of air holes may also penetrate from the edge of the first membrane 11 to the first optical surface of the first membrane 11, and a furrow-shaped groove communicating with the plurality of air holes of the first membrane 11 may be provided on a side of the second membrane 12 close to the cavity 101, so as to form an L-shaped air hole communicating with the cavity 101 as a whole (see fig. 12). That is, in the embodiment shown in fig. 12, the air holes 11a (taking the air holes 11a as an example) may include a hole provided on the first membrane 11 and a groove provided on the second membrane 12 and communicating with the cavity 101, and when the first membrane 11 is combined with the second membrane 12, the hole provided on the first membrane 11 and the groove provided on the second membrane 12 are aligned to communicate with each other, so that the air holes 11a communicate the outside with the cavity 101.

That is, in some examples, the air holes 11a may include a first portion (i.e., a hole formed on the first membrane 11) and a second portion (i.e., a groove formed on the second membrane 12) formed in an L shape, and an axis of the first portion may be orthogonal to the first optical surface and an axis of the second portion may be parallel to the first optical surface. In this case, the cavity 101 can be made to communicate with the outside, so that the pressure sensor 1 capable of sensing the sound pressure can be provided.

According to the manufacturing method of the present embodiment, the uniformity of the sensing unit 10 can be improved, thereby improving the uniformity of the pressure sensor 1.

While the present disclosure has been described in detail in connection with the drawings and examples, it should be understood that the above description is not intended to limit the disclosure in any way. Those skilled in the art can make modifications and variations to the present disclosure as needed without departing from the true spirit and scope of the disclosure, which fall within the scope of the disclosure.

Claims

1. A high-consistency preparation method of a sensitive unit of an optical fiber Fabry-Perot pressure sensor is characterized in that,

the method comprises the following steps:

preparing a first quartz plate having opposite upper and lower surfaces, a second quartz plate having opposite upper and lower surfaces, and a third quartz plate having opposite upper and lower surfaces; polishing the upper surface of the first quartz plate, polishing the upper surface and the lower surface of the second quartz plate, and polishing the upper surface of the third quartz plate; manufacturing a plurality of grooves on the upper surface of the first quartz plate or the upper surface of the second quartz plate in a preset distribution mode; manufacturing a plurality of through holes on the third quartz plate in the preset distribution mode; bonding the upper surface of the first quartz plate to the upper surface of the second quartz plate in a manner of covering the plurality of grooves, and bonding the upper surface of the third quartz plate to the lower surface of the second quartz plate to form a laminated body in which each groove and each through hole are coaxial, respectively; and cutting the plurality of grooves to obtain a plurality of sensitive units.

2. The high-consistency production method according to claim 1,

the predetermined distribution pattern at least comprises the wheel base between the grooves.

3. The high-consistency production method according to claim 1,

the lower surface of the third quartz plate of the laminated body is provided with bosses which are coaxial with the through holes and are made at the positions corresponding to the through holes, the bosses are cylindrical, and the diameter of each boss is smaller than 2.5 mm.

4. The high-consistency production method according to claim 1,

and manufacturing air holes which pass through the first quartz plate and are communicated with the grooves in the laminated body.

5. The high-consistency production method according to claim 4,

the air holes are L-shaped.

6. The high-consistency production method according to claim 4,

the number of the air holes is multiple, and the air holes are uniformly arranged around the axis of the through hole.

7. An optical fiber Fabry-Perot pressure sensor is characterized in that,

comprises a sensitive unit and an optical fiber,

the sensing unit comprises a first diaphragm, a second diaphragm and a third diaphragm which are sequentially stacked, a microcavity and a first reflecting surface and a second reflecting surface which are respectively positioned on two opposite sides of the microcavity and are parallel to each other are formed between the first diaphragm and the second diaphragm, a through hole which is coaxial with the microcavity and is not communicated with the microcavity is formed on the third diaphragm, the size of the optical fiber is matched with that of the through hole, the optical fiber is embedded in the through hole, the axis of the optical fiber is orthogonal to the first reflecting surface and the second reflecting surface, and light entering the microcavity through the optical fiber can be reflected between the first reflecting surface and the second reflecting surface, wherein the sensing unit is prepared according to the high-consistency preparation method of any one of claims 1 to 6.

8. The fiber optic Fabry-Perot pressure sensor of claim 7,

the optical fiber comprises a bare fiber and a glass tube with a hollow part, the size of the glass tube is matched with that of the through hole, the glass tube is embedded in the through hole, the size of the bare fiber is matched with that of the hollow part, the bare fiber is embedded in the hollow part, the axis of the hollow part is orthogonal to the first reflecting surface and the second reflecting surface, and the end face of one end of the bare fiber embedded in the hollow part is parallel to the first reflecting surface and the second reflecting surface.

9. The fiber optic Fabry-Perot pressure sensor of claim 7,

and a collimation element configured to collimate light is arranged on the end face of one end of the optical fiber embedded in the hollow part.

10. The fiber optic Fabry-Perot pressure sensor of claim 7,

the glass tube is coupled with the sensing unit via high temperature welding, and the bare optical fiber is coupled with the glass tube via high temperature welding.