Vernier sensitization vacuum pressure sensor based on optical fiber end face interference

Abstract

The invention discloses a vernier sensitization vacuum pressure sensor based on optical fiber end face interference, and relates to the technical field of film sensors. The problem of low measurement precision caused by electromagnetic interference of a traditional capacitive film pressure sensor is solved. An interference cavity formed between the lower end face of the center optical fiber of the separated vernier assembly and the pressure sensing diaphragm serves as a sensing cavity for pressure detection, the sensing cavity (an optical fiber Fabry-Perot structure) formed by the pressure sensing diaphragm and the center optical fiber is adopted to replace a capacitor structure, optical waves are used for measurement, electric signals are not transmitted in the optical fiber, and the measurement precision is high. Therefore, the cable has excellent anti-electromagnetic interference and long-distance transmission capabilities. The pressure sensor is mainly used for pressure measurement.

Description

Technical Field

[0001] The invention relates to the technical field of thin film sensors, and in particular to a vernier-sensitized vacuum pressure sensor based on optical fiber end face interference. Background Art

[0002] In order to accurately and precisely detect and control the vacuum degree in the vacuum chamber, a capacitance film vacuum gauge is generally used for measurement. This vacuum gauge is equipped with a pressure-sensing film inside. The detection principle is: the film is deformed and offset by the different pressures on both sides of the film, thereby changing the distance between the film and the electrode, and then changing the capacitance. By recording the change in capacitance, the pressure change is finally obtained. Capacitance film vacuum gauges cannot avoid the influence of traditional environmental factors such as temperature, humidity, electric field, and magnetic field interference, which in turn causes deviations in the measurement of their pressure values, which limits their further application.

[0003] At present, the key problem of consolidating the diaphragm and the cavity in the capacitive thin film pressure sensor (diaphragm-type optical fiber Fabry-Perot pressure sensor) is the problem. Laser bonding has complex equipment, high cost, and stress concentration in the preparation of sensors, which is not suitable for large-scale production; the operation is complicated and the investment in production lines is huge. In addition, in the current use of the vernier effect to enhance the sensitivity of optical sensors, a fixed reference cavity length is often used for data vernier amplification. Such a setting has a narrow range of application and is difficult to adjust. When different pressures act on the pressure-sensitive diaphragm, the wavelength may change slightly or too much, making it difficult to perform low-pressure observations. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of low measurement accuracy caused by electromagnetic interference in traditional capacitive film pressure sensors. The present invention provides a vernier-sensitized vacuum pressure sensor based on optical fiber end face interference.

[0005] A vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference comprises an upper shell, a lower shell, a pressure-sensitive diaphragm, and a separate vernier assembly;

[0006] The pressure-sensitive diaphragm is arranged between the upper shell and the lower shell, and a vacuum space is formed between the upper shell and the pressure-sensitive diaphragm, and a space to be measured is formed between the lower shell and the pressure-sensitive diaphragm;

[0007] The separate vernier assembly penetrates the upper shell and extends into the vacuum space, the lower end surface of the central optical fiber of the separate vernier assembly is parallel to the pressure-sensitive diaphragm, and an interference cavity is formed between the two as a sensing cavity;

[0008] A getter groove is provided on the top of the upper shell for discharging the getter, and the getter groove is communicated with the vacuum space;

[0009] After the gas introduced into the air inlet at the bottom of the lower shell causes the pressure-sensitive diaphragm to deform, the length of the sensing cavity changes, and the light incident from the top of the central optical fiber in the separated cursor assembly is reflected by the lower end surface of the bottom end of the central optical fiber, and the light transmitted through the lower end surface is reflected by the pressure-sensitive diaphragm and then returns to the central optical fiber along the original path, which interferes with the light. The interference light is used as the signal light;

[0010] The interference light generated by the corresponding vernier reference part in the separate vernier assembly is used as reference light to amplify the signal light; wherein the vernier reference parts with reference cavities of different lengths in the separate vernier assembly correspond to different magnification factors.

[0011] Preferably, the separate vernier assembly includes a central optical fiber, a plurality of vernier reference pieces, and a metal cylinder;

[0012] The interferometric cavities of the plurality of vernier reference pieces have different lengths, the interferometric cavity is used as a reference cavity, and the vernier reference piece is used to generate reference light;

[0013] The central optical fiber and the plurality of vernier reference parts are all arranged in the metal cylinder, and the plurality of vernier reference parts are arranged on the top of the metal cylinder.

[0014] Preferably, the vernier reference member comprises a reference optical fiber, a microcrystalline glass and a metal sheet arranged in sequence from bottom to top;

[0015] The thickness of the microcrystalline glass is used as the reference cavity length of the vernier reference part, and the length of the reference cavity of the vernier reference part is smaller than the length of the sensing cavity formed between the lower end surface of the central optical fiber and the pressure-sensitive diaphragm;

[0016] The light entering through the bottom end of the reference optical fiber is reflected by the lower surface of the microcrystalline glass, and interferes with the light that passes through the microcrystalline glass, is reflected by the metal sheet, and then returns to the reference optical fiber along the original path. The interference light is used as the reference light.

[0017] Preferably, the vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference further includes an anti-deposition structure installed at the air inlet for buffering the incoming gas and blocking particulate matter in the gas.

[0018] Preferably, the anti-deposition structure comprises a cylindrical structure, filter screens arranged at both end ports of the cylindrical structure, and multi-layer guide plates arranged alternately from top to bottom in the cylindrical structure;

[0019] The filter screens at the two end ports have different transmittances.

[0020] Preferably, the guide plate comprises a downwardly inclined arc-shaped base plate and an additional baffle plate superimposed on each other, and the downwardly inclined arc-shaped base plate is located above the additional baffle plate.

[0021] The axial section of the additional baffle is an inverted M-shaped structure.

[0022] Preferably, the vernier-sensitized vacuum pressure sensor based on optical fiber end face interference further includes an electrostatic dust removal device arranged outside the anti-deposition structure, and the electrostatic dust removal device is used to electrostatically remove dust from the introduced gas.

[0023] Preferably, the vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference further includes an aerogel felt and a housing;

[0024] The aerogel felt is wrapped around the outside of the upper shell and the lower shell, and the outer shell is arranged outside the aerogel felt.

[0025] Preferably, the vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference further comprises a graphene layer, which is arranged between the aerogel felt and the housing, and an extraction electrode is arranged on the graphene layer;

[0026] The graphene layer is heated by electrodes to keep the vacuum space at a constant temperature.

[0027] Preferably, the pressure-sensitive diaphragm is fixed to the upper shell and the lower shell by high-temperature bonding technology or glass paste.

[0028] Advantages of the present invention:

[0029] The present invention uses the sensing cavity structure formed between the central optical fiber and the pressure-sensitive diaphragm to measure pressure, and changes the traditional capacitor structure into a pressure-sensitive diaphragm and optical fiber end face sensing cavity structure for detection. Since the optical fiber itself does not transmit electrical signals and has no electrical contact parts, it avoids interference problems in the electromagnetic environment and does not affect performance due to electrode oxidation or wear. In addition, the optical fiber is small in size and is convenient for integration into complex systems without being constrained by external power supply connections. The present invention can eliminate the influence of electromagnetic interference and is more suitable for applications with complex electromagnetic environments. The pressure-sensitive diaphragm and central optical fiber structure have high sensitivity and resolution, and can accurately detect small pressure difference changes based on the interference characteristics of light.

[0030] In addition, this sensor is designed with a vernier reference part with different length reference cavities for optional vernier magnification. Different vernier magnifications can be selected in different application environments according to the vernier effect, and the magnification factor can be selected. The vernier reference part improves the measurement accuracy, can accurately magnify and compare within different diaphragm strain ranges, can better capture small differences and changes, and increases flexibility and measurement range.

[0031] The present invention can not only improve the measurement accuracy, but also avoid the influence of external interference and improve the stability of the test signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to the present invention;

[0033] Figure 2 is a top view of the separate cursor assembly 4;

[0034] Figure 3 is an axial cross-sectional view of the separate cursor assembly 4;

[0035] Figure 4 Schematic diagram of the structure of the anti-deposition structure 5.

[0036] Figure 5 It is a schematic diagram of the structure in which a layer of aluminum oxide film is bonded to the pressure-sensitive membrane 3;

[0037] Figure 6 This is a test data diagram of the vernier-sensitized vacuum sensor of the present invention at a certain magnification;

[0038] in, Figure 6 a is a reflection drift spectrum diagram of the output of the sensing cavity between the lower end surface of the central optical fiber 4-1 and the pressure-sensitive diaphragm 3 after being subjected to a pressure of 10 torr; Figure 6 b is the reflection drift spectrum diagram of the sensing cavity between the lower end face of the central optical fiber 4-1 and the pressure-sensitive diaphragm 3 after being subjected to a pressure of 10 torr and superimposed with a certain reference cavity;

[0039] Figure 7 This is the interference spectrum diagram of the vernier-sensitized vacuum pressure sensor based on optical fiber end face interference after superposition under the vernier effect. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0042] Specific implementation method 1. Figure 1 The present embodiment is described. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference described in the present embodiment comprises an upper shell 1, a lower shell 2, a pressure-sensitive diaphragm 3, and a separate vernier assembly 4;

[0043] The pressure-sensitive diaphragm 3 is arranged between the upper shell 1 and the lower shell 2, and a vacuum space is formed between the upper shell 1 and the pressure-sensitive diaphragm 3, and a space to be measured is formed between the lower shell 2 and the pressure-sensitive diaphragm 3;

[0044] The separate cursor assembly 4 penetrates the upper housing 1 and extends into the vacuum space. The lower end surface of the central optical fiber 4-1 of the separate cursor assembly 4 is parallel to the pressure-sensitive diaphragm 3, and an interference cavity is formed between the two as a sensing cavity.

[0045] A getter groove 1-1 is provided on the top of the upper shell 1 for discharging the getter, and the getter groove 1-1 is connected to the vacuum space;

[0046] After the gas introduced into the air inlet 2-1 opened at the bottom of the lower shell 2 causes the pressure-sensitive diaphragm 3 to deform, the length of the sensing cavity changes, and the light incident from the top of the central optical fiber 4-1 in the separated cursor assembly 4 is reflected by the lower end surface of the bottom end of the central optical fiber 4-1, and the light transmitted through the lower end surface is reflected by the pressure-sensitive diaphragm 3 and then returns to the central optical fiber 4-1 along the original path, which interferes with the light. The interference light serves as the signal light;

[0047] The interference light generated by the corresponding vernier reference part 4-2 in the separate vernier assembly 4 is used as reference light to amplify the signal light; wherein the vernier reference part 4-2 with reference cavities of different lengths in the separate vernier assembly 4 corresponds to different magnification factors.

[0048] The getter is used to ensure the vacuum degree inside the vacuum space to prevent insufficient vacuum degree in subsequent practical applications.

[0049] The pressure is measured by using the sensing cavity structure formed between the central optical fiber and the pressure-sensitive diaphragm, and the traditional capacitor structure is changed to a pressure-sensitive diaphragm and an optical fiber end face sensing cavity structure for detection. Since the optical fiber itself does not transmit electrical signals and has no electrical contact parts, it avoids interference problems in the electromagnetic environment and does not affect performance due to electrode oxidation or wear. In addition, the optical fiber is small in size and is convenient for integration into complex systems without being constrained by external power connections. The present invention can eliminate the influence of electromagnetic interference and is more suitable for applications with complex electromagnetic environments. The pressure-sensitive diaphragm and the central optical fiber structure have high sensitivity and resolution, and can accurately detect small pressure difference changes based on the interference characteristics of light.

[0050] In specific applications, a layer of aluminum oxide film is bonded on the surface of the pressure-sensitive diaphragm 3 , which is conducive to forming a more solid bond between the pressure-sensitive diaphragm 3 and the upper cavity 1 and the lower cavity 2 .

[0051] See also Figure 2 , the separate vernier assembly 4 includes a central optical fiber 4-1, a plurality of vernier reference pieces 4-2 and a metal cylinder 4-3;

[0052] The interference cavities of the multiple vernier reference pieces 4-2 have different lengths, the interference cavity is used as a reference cavity, and the vernier reference piece 4-2 is used to generate reference light;

[0053] The central optical fiber 4-1 and the plurality of vernier reference parts 4-2 are both arranged in the metal cylinder 4-3, and the plurality of vernier reference parts 4-2 are arranged on the top of the metal cylinder 4-3.

[0054] In specific applications, three reference cavities with different lengths can be set, and each length reference cavity corresponds to a corresponding magnification factor. The reference light generated by the vernier reference part 4-2 of the different length reference cavities is used to perform vernier amplification on the signal light output by the central optical fiber, and a similar spectral offset can be obtained to achieve pressure measurement. Different magnification factors can be selected for the spectral drift after a single sensor cavity is subjected to a certain pressure.

[0055] See also Figure 3 The vernier reference part 4-2 includes a reference optical fiber 4-2-1, a microcrystalline glass 4-2-2 and a metal sheet 4-2-3 arranged in sequence from bottom to top;

[0056] The thickness of the microcrystalline glass 4-2-2 is used as the reference cavity length of the vernier reference piece 4-2, and the length of the reference cavity of the vernier reference piece 4-2 is less than the length of the sensing cavity formed between the lower end surface of the central optical fiber 4-1 and the pressure-sensitive diaphragm 3;

[0057] The light entering through the bottom end of the reference optical fiber 4-2-1 is reflected by the lower surface of the microcrystalline glass 4-2-2, and interferes with the light that passes through the microcrystalline glass 4-2-2, is reflected by the metal sheet 4-2-3, and then returns to the reference optical fiber 4-2-1 along the original path. The interference light is used as the reference light.

[0058] In this preferred embodiment, the vernier reference part 4-2 uses a microcrystalline glass 4-2-2 as the cavity length of the sensing cavity to form a strong reflection interface at the top of the reference optical fiber 4-2-1, and the microcrystalline glass 4-2-2 is not easily deformed by the external temperature. The metal sheet 4-2-3 acts as a light barrier to effectively block the further propagation of light, reflect the light beam back into the optical fiber, effectively control the transmission path of light, and avoid external light interference.

[0059] Furthermore, the vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference further includes an anti-deposition structure 5 installed at the gas inlet, which is used to buffer the incoming gas and block particles in the gas. Figure 4 The anti-deposition structure 5 includes a cylindrical structure 5-1, a filter screen 5-2 disposed at both end ports of the cylindrical structure, and a multi-layer guide plate 5-3 arranged alternately from top to bottom in the cylindrical structure;

[0060] The filter screens 5 - 2 at the two end ports have different transmittances.

[0061] In this preferred embodiment, a multi-layer guide plate 5-3 and two layers of gas filters with different gas permeabilities are used to provide good protection for the pressure-sensitive diaphragm 3, effectively preventing particles in the gas from reaching the pressure-sensitive diaphragm 3 and depositing on the pressure-sensitive diaphragm 3, thereby affecting the precise measurement of the sensor. In specific applications, the filter 5-2 located below has a higher gas permeability and a larger pore size than the filter 5-2 located above, while the second gas filter 5-4 located above has a lower gas permeability and a smaller pore size.

[0062] As an example, the guide plate 5-3 includes a downwardly inclined arc-shaped base plate 5-3-1 and an additional baffle plate 5-3-2, and the downwardly inclined arc-shaped base plate 5-3-1 is located above the additional baffle plate 5-3-2, and the axial cross section of the additional baffle plate 5-3-2 is an inverted M-shaped structure. This structure can further divert, guide, and slow down the airflow to ensure that the airflow smoothly enters the space to be tested.

[0063] The arc-shaped base plate 5-3-1 and the additional baffle plate 5-3-2 are provided with a multi-layer structure, and the guide plates 5-3 are arranged in parallel and spaced apart. As a result, the particles in the gas are blocked multiple times by the filter screen 5-2 located below, the multi-layer guide plates 5-3 and the filter screen 5-2 located above, and the particle content in the gas is reduced to a lower level, thereby forming a better protection effect on the pressure-sensitive diaphragm 3.

[0064] See also Figure 1 The vernier-sensitized vacuum pressure sensor based on optical fiber end face interference also includes an electrostatic dust removal device 6 arranged outside the anti-deposition structure 5, and the electrostatic dust removal device 6 is used to electrostatically remove dust from the introduced gas.

[0065] In the preferred embodiment, the electrostatic dust removal device 6 is a tubular structure wrapped around the outside of the anti-deposition structure 5, and an electrostatic field is formed at the anti-deposition structure 5 according to the principle of electrostatic adsorption. The electrostatic dust removal device 6 is supplied with alternating current, and the dust deposited in the anti-deposition structure 5 can be cleaned according to the characteristics of alternating current. Specifically, the multi-layer guide plates 5-3 in the anti-deposition structure 5 are coated with Teflon material on the surface by spraying, so as to reduce the accumulation of impurities such as dust in the gas, so as to reduce the accumulation of impurities such as particles in the gas, and facilitate subsequent cleaning.

[0066] See also Figure 1 , the vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference further includes an aerogel felt 7 and a housing 8;

[0067] The aerogel felt 7 is wrapped around the outside of the upper shell 1 and the lower shell 2 , and the outer shell 8 is arranged outside the aerogel felt 7 .

[0068] The vernier-sensitized vacuum pressure sensor based on optical fiber end face interference further includes a graphene layer 9, which is arranged between the aerogel felt 7 and the housing 8, and an extraction electrode 9-1 is arranged on the graphene layer 9;

[0069] The graphene layer 9 is heated by the electrode 9-1 to keep the vacuum space at a constant temperature.

[0070] In specific application, the specific process of assembling the aerogel felt 7, the shell 8 and the graphene layer 9 is as follows: the pressure-sensitive diaphragm 3 is fixed to the upper shell 1 and the lower shell 2 by high-temperature bonding technology or glass slurry.

[0071] See also Figure 4 Before the pressure-sensitive membrane 3 is bonded to the upper shell 1 and the lower shell 2 at high temperature, a layer of aluminum oxide film is bonded to the pressure-sensitive membrane 3 at room temperature using surface activation bonding technology, see Figure 5 , the aluminum oxide film is in contact with the pressure-sensitive diaphragm 3 and the upper shell 1 and the lower shell 2, and when performing high-temperature bonding technology, an instrument is used to apply uniform prestress to the pressure-sensitive diaphragm 3 to achieve a more solid bond between the pressure-sensitive diaphragm 3 and the upper shell 1 and the lower shell 2. After the upper shell 1 and the lower shell 2, as well as the pressure-sensitive diaphragm 3 are prepared, a layer of aerogel felt 7 is evenly covered on the outside to maintain temperature stability, and a graphene layer 9 is coated on the outside of the aerogel felt 7 for heating and external environment control, and finally a metal shell 8 is used for the outermost packaging.

[0072] Principle analysis:

[0073] The vernier-sensitized vacuum pressure sensor based on optical fiber end face interference described in this embodiment is used for pressure detection. When a certain pressure acts on the pressure-sensitive diaphragm 3, the pressure-sensitive diaphragm 3 will undergo a certain deformation, resulting in a change in the cavity length between the pressure-sensitive diaphragm 3 and the central optical fiber 4-1. At this time, an interference cavity is formed between the lower end face of the central optical fiber 4-1 of the separate vernier component 4 and the pressure-sensitive diaphragm 3 as a sensing cavity to measure the pressure to be measured. The interference light generated by the corresponding vernier reference part 4-2 in the separate vernier component 4 is used as a reference light. After the signal light output by the central optical fiber 4-1 is coupled with the reference light through an optical coupler, the receiving end obtains the superimposed spectrum of the signal light and the reference light. The superimposed spectrum is distributed periodically, and the free spectral range of the superimposed spectrum is related to the free spectral range of the signal light and the reference light. When the spectrum output by the central optical fiber drifts slightly, and the spectrum of the vernier reference 4-2 (fiber Fabry-Perot cavity) does not change, the slight change can be amplified by detecting the positions of the original aligned peaks (or troughs) and the currently aligned peaks (or troughs). The total reflected light intensity obtained by using the vernier effect after the superimposed spectrum is superimposed with the reflection intensity A of the central fiber Fabry-Perot structure and the reflection intensity B of a certain fiber Fabry-Perot structure corresponding to the selected corresponding vernier reference 4-2 is:

[0074] I = A + B (Formula 1);

[0075] When used to measure vacuum pressure, the gas to be measured will first pass through the anti-deposition structure 5 at the bottom air inlet of the lower shell 2, and enter the space to be measured after the impurities in the gas are filtered and the gas is slowed down. The pressure-sensitive diaphragm 3 will produce a certain deformation toward the vacuum space under the action of the pressure difference between the two spaces on both sides, causing the cavity length between the central optical fiber 4-1 and the pressure-sensitive diaphragm 3 to change. The changed cavity length is q. Using the interference principle of the optical fiber Fabry-Perot sensor, the optical fiber Fabry-Perot cavity is modulated by the two reflection surfaces of the optical fiber end face a of the central optical fiber 4-1 and the reflection surface b of the pressure-sensitive diaphragm 3, and the reflected light intensity is

[0076]

[0077] Since the light is incident vertically, the incident angle is 0°, and there is a certain distance between the central optical fiber 4-1 and the pressure-sensitive diaphragm 3, only two reflections occur. In this case, the reflected light intensity A of the sensing cavity and the reflected light intensity B of the reference cavity corresponding to the separate vernier component 4 can be expressed as:

[0078]

[0079] Where c and d are the reflectivities of the two reflective surfaces of the reference cavity, q 1 is the length of the sensing cavity, q 2 is the cavity length of the reference cavity, and R is the input light intensity.

[0080] Therefore, according to the vernier effect, the two reflected light intensities are superimposed and input into the spectrometer. The interference signal will change due to the pressure on the pressure-sensitive diaphragm 3 and the selected vernier reference cavity. The host computer can then demodulate the information of the spectrum change to analyze and calculate the current specific cavity length value of the sensing cavity. By analyzing the relationship between the peak drift of the reflected spectrum envelope after the spectrum of the sensing cavity and the reference light spectrum are superimposed, the pressure applied by the outside world can be accurately calculated.

[0081] Verification test:

[0082] The effectiveness of the present invention is illustrated by the following verification method, specifically:

[0083] First, preparing the vacuum pressure sensor of the all-quartz vacuum structure includes the following steps:

[0084] The first step is to set up the pressure-sensitive diaphragm and the shell, and use surface activated bonding technology to prepare a layer of aluminum oxide film at the parallel contact surface between the pressure-sensitive diaphragm and the shell, and ensure that the thickness of the aluminum oxide film is much smaller than the thickness of the pressure-sensitive diaphragm. After preparation, the pressure-sensitive diaphragm is placed between the upper shell and the lower shell, and the equipment is used to apply uniform prestress on the pressure-sensitive diaphragm on all sides, and then the high-temperature bonding technology is used to achieve a firm connection between the diaphragm and the upper and lower shells.

[0085] The second step is to set a getter and a separate vernier assembly. A getter is set on the upper shell to ensure the vacuum degree inside the vacuum space. An exhaust hole is set to vacuum the space formed between the upper shell and the pressure-sensitive diaphragm after bonding. The separate vernier assembly is set in the middle position above the upper shell, parallel to the pressure-sensitive diaphragm to form an optical fiber detection interference cavity structure. The separate vernier assembly consists of a central optical fiber 4-1, a plurality of vernier reference parts 4-2 and a metal cylinder 4-3.

[0086] The third step is to set up the external structure, which includes aerogel felt, graphene layer and 316L stainless steel shell. A certain thickness of aerogel felt is evenly bonded to the outside of the quartz shell to reduce the influence of external temperature; graphene is evenly coated on the outside of the aerogel felt for temperature control, and the outermost layer is set with 316L stainless steel for external protection.

[0087] In the above preparation process, the upper shell, the lower shell and the pressure-sensitive diaphragm are all made of quartz material to prepare the sensor, which further improves the ability to resist electromagnetic interference. Quartz glass has excellent mechanical properties, stable chemical properties and thermodynamic properties, and excellent optical properties. Quartz material has high stability and is not easily affected by ambient temperature, humidity and electromagnetic interference. In addition, quartz material has excellent high temperature resistance, can work stably in high temperature environment, has strong resistance to chemical corrosion, and can be used in harsh chemical environments. Due to the low noise characteristics of quartz material, the prepared pressure-sensitive diaphragm can provide clear signal output.

[0088] In this design, the pressure-sensitive diaphragm, upper shell and lower shell are not limited to quartz structures, and structures such as silicon, microcrystalline glass, stainless steel, and sapphire can also be selected.

[0089] Figure 6 The comparison of the amplification factor and the non-amplification factor of the vernier-sensitized vacuum pressure sensor based on fiber end-face interference after selecting a vernier reference cavity and the central optical fiber to form a vernier effect is given in the paper.

[0090] Figure 7 The spectral diagram of the vacuum sensor with all-quartz structure is given when a certain pressure acts on the pressure-sensitive diaphragm.

[0091] Figure 6 a shows that after the cavity length of the sensing cavity changes, the wavelength drift of the reflection spectrum output by a single sensing cavity is about 1.5nm. Figure 6 After the length of the sensing cavity in b is changed, the wavelength drift of the reflected spectrum output after the spectrum of the sensing cavity and the reference cavity is superimposed is about 9nm. Figure 6 a and Figure 6 b As a result, the vernier effect formed by the superposition of the sensing cavity reflection spectrum and the reference cavity reflection spectrum can amplify the drift of the sensing cavity reflection spectrum by about 6 times.

[0092] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference, characterized in that: It comprises an upper housing (1), a lower housing (2), a pressure-sensitive diaphragm (3), and a separate cursor assembly (4); The pressure-sensitive diaphragm (3) is arranged between the upper shell (1) and the lower shell (2), and a vacuum space is formed between the upper shell (1) and the pressure-sensitive diaphragm (3), and a space to be measured is formed between the lower shell (2) and the pressure-sensitive diaphragm (3); The separate cursor assembly (4) penetrates the upper shell (1) and extends into the vacuum space; the lower end surface of the central optical fiber (4-1) of the separate cursor assembly (4) is parallel to the pressure-sensitive diaphragm (3), and an interference cavity is formed between the two as a sensing cavity; A getter groove (1-1) is provided on the top of the upper shell (1) for discharging the getter, and the getter groove (1-1) is connected to the vacuum space; The gas introduced through the air inlet (2-1) opened at the bottom of the lower housing (2) causes the pressure-sensitive diaphragm (3) to deform, thereby changing the length of the sensing cavity. The light incident from the top of the central optical fiber (4-1) in the separated cursor assembly (4) is reflected by the lower end surface of the bottom end of the central optical fiber (4-1) and the light transmitted through the lower end surface is reflected by the pressure-sensitive diaphragm (3) and then returns to the central optical fiber (4-1) along the original path, causing interference. The interference light serves as signal light. Interference light generated by a corresponding vernier reference piece (4-2) in the separate vernier assembly (4) is used as reference light to amplify the signal light; wherein the vernier reference pieces (4-2) with reference cavities of different lengths in the separate vernier assembly (4) correspond to different magnification factors.

2. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 1 is characterized in that: The separate cursor assembly (4) includes a central optical fiber (4-1), a plurality of cursor reference pieces (4-2) and a metal cylinder (4-3); The interference cavities of the plurality of vernier reference pieces (4-2) have different lengths, the interference cavity is used as a reference cavity, and the vernier reference piece (4-2) is used to generate reference light; The central optical fiber (4-1) and the plurality of vernier reference parts (4-2) are both arranged in the metal cylinder (4-3), and the plurality of vernier reference parts (4-2) are arranged on the top of the metal cylinder (4-3).

3. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 2 is characterized in that: The vernier reference part (4-2) comprises a reference optical fiber (4-2-1), a microcrystalline glass (4-2-2) and a metal sheet (4-2-3) which are arranged in sequence from bottom to top; The thickness of the microcrystalline glass (4-2-2) is used as the reference cavity length of the vernier reference piece (4-2), and the length of the reference cavity of the vernier reference piece (4-2) is smaller than the length of the sensing cavity formed between the lower end surface of the central optical fiber (4-1) and the pressure-sensitive diaphragm (3); The light entering through the bottom end of the reference optical fiber (4-2-1) is reflected by the lower surface of the microcrystalline glass (4-2-2), and interferes with the light that passes through the microcrystalline glass (4-2-2), is reflected by the metal sheet (4-2-3), and then returns to the reference optical fiber (4-2-1) along the original path. The interference light serves as the reference light.

4. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 1 is characterized in that: It also includes an anti-deposition structure (5) installed at the gas inlet, which is used to buffer the incoming gas and block the particles in the gas.

5. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 4 is characterized in that: The anti-deposition structure (5) comprises a cylindrical structure (5-1), filter screens (5-2) arranged at both end ports of the cylindrical structure, and multi-layer guide plates (5-3) arranged alternately from top to bottom in the cylindrical structure; The filter screens (5-2) at the two end ports have different transmittances.

6. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 5 is characterized in that: The guide plate (5-3) comprises a downwardly inclined arc-shaped base plate (5-3-1) and an additional baffle plate (5-3-2) stacked together, and the downwardly inclined arc-shaped base plate (5-3-1) is located above the additional baffle plate (5-3-2). The axial cross section of the additional baffle (5-3-2) is an inverted M-shaped structure.

7. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 1 is characterized in that: It also includes an electrostatic dust removal device (6) arranged outside the anti-deposition structure (5), and the electrostatic dust removal device (6) is used to perform electrostatic dust removal on the introduced gas.

8. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 1 is characterized in that: Also includes an aerogel felt (7) and a shell (8); The aerogel felt (7) is wrapped around the outside of the upper shell (1) and the lower shell (2), and the outer shell (8) is arranged outside the aerogel felt (7).

9. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 8 is characterized in that: It also includes a graphene layer (9), which is arranged between the aerogel felt (7) and the housing (8), and an extraction electrode (9-1) is arranged on the graphene layer (9); The graphene layer (9) is heated by the electrode (9-1) so that the vacuum space is kept at a constant temperature.

10. The vernier-sensitized vacuum pressure sensor based on optical fiber end-face interference according to claim 1, characterized in that: The pressure-sensitive diaphragm (3) is fixed to the upper shell (1) and the lower shell (2) by means of high-temperature bonding technology or glass paste.

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