High-precision alignment proximity sensor based on heterogeneous reflection microwave resonator

Abstract

The invention is suitable for the technical field of microwave sensing, and provides a high-precision alignment proximity sensor based on a heterogeneous reflection microwave resonator, which comprises a microwave resonator and a heterogeneous reflection sheet, the microwave resonator is composed of an SMA connector, an outer conductor, an inner conductor, a first metal column, a second metal column and a third metal column, the SMA connector is connected with the outer conductor and the inner conductor, the inner conductor is arranged in a hollow structure in the outer conductor, and each metal column is connected with the outer conductor 102 and the inner conductor 103; the heterogeneous reflector plate is composed of an inner reflector plate 104 and an outer reflector plate 105, and the inner reflector plate 104 is embedded in the center of the outer reflector plate 105. According to the sensor provided by the invention, the distance and deviation in the axial and radial dimensions can be measured without crosstalk based on a single sensor, and dual-function sensing of alignment and proximity monitoring is realized at the same time, so that high-precision alignment and proximity sensing is realized.

Description

Technical Field

[0001] The present application belongs to the field of microwave sensing technology, and in particular relates to a high-precision alignment proximity sensor based on a heterogeneous reflective microwave resonator. Background Art

[0002] In the fields of microelectronics assembly, semiconductor manufacturing, optical device coupling alignment, etc., when it comes to very precise and sensitive optical lenses, semiconductor wafers, MEMS components and other workpieces, it is necessary to ensure high-precision positioning of each process link without damaging the workpiece, so non-contact measurement technology of micro-scale displacement is crucial. Proximity sensors can sense the displacement of target objects and measure their proximity distance. They are widely used in distance or displacement monitoring in industrial automation, consumer electronics, intelligent transportation and other fields. Its main types include capacitive, photoelectric, ultrasonic, optical interference, Hall effect sensors, etc., which are based on the detection principles of capacitance change, detection light flight time, ultrasonic echo, optical interference intensity change, and magnetic field intensity change when the object approaches to sense the proximity or distance change of the object. Proximity sensors are usually only used to measure one-dimensional distance information, and it is difficult to detect the lateral misalignment that may exist between processing equipment or workpieces. In the semiconductor industry, high-end precision manufacturing and other industries, in addition to the proximity distance, the degree of deviation in the lateral plane must also be measured to achieve precise alignment. Three or more proximity sensors can be used to measure displacement information in different dimensions, so as to achieve simultaneous measurement of lateral alignment and longitudinal proximity. However, this will not only increase costs, but also make the sensor structure complex and bulky, and limit its usage scenarios.

[0003] Displacement sensors based on microwave technology have the characteristics of low cost, simple structure, high sensitivity, passive measurement, easy installation, real-time response, and strong resistance to interference from harsh environments. They have been increasingly used in the field of high-precision industrial automation. According to the structure of microwave sensors, they are mainly divided into planar transmission line type and coaxial cable type. A typical microwave displacement sensor consists of a sensing element and a movable response element attached to the target object. Its basic working principle is to obtain the transmission or reflection coefficient based on the microwave resonant frequency, amplitude or phase measured by the sensing element, which is used to demodulate the horizontal misalignment degree or the vertical distance between the movable response element and the sensing element. Compared with planar transmission line type microwave sensors, coaxial cable type microwave sensors have the characteristics of easy manufacturing, high mechanical strength, and ultra-high temperature stability, and have better applicability to various complex production workshop environments. However, microwave displacement sensors can usually only measure horizontal or vertical displacement information separately. Therefore, there is an urgent need for a high-precision alignment proximity sensor that can simultaneously measure the horizontal misalignment and vertical distance. Summary of the invention

[0004] The embodiments of the present application provide a high-precision alignment proximity sensor based on a heterogeneous reflective microwave resonator and an application method of the sensor, which can solve the current problem of lack of a high-precision alignment proximity sensor that can simultaneously measure both lateral misalignment and longitudinal distance.

[0005] In a first aspect, an embodiment of the present application provides a high-precision alignment proximity sensor based on a heterogeneous reflective microwave resonator, comprising: the sensor is composed of a microwave resonator and a heterogeneous reflective plate, the microwave resonator and the heterogeneous reflective plate are aligned on the same axis, and the distance between the microwave resonator and the heterogeneous reflective plate is a first preset distance; the microwave resonator is composed of an SMA connector 101, an outer conductor 102, an inner conductor 103, a first metal column 106, a second metal column 107, and a third metal column 108, the SMA connector 101 and the outer conductor 102 and the inner conductor 103 are aligned The inner conductor 103 is placed in a hollow structure inside the outer conductor 102, and an insulating dielectric material is filled in the hollow structure of the outer conductor 102 except for the inner conductor 103. The first metal column 106, the second metal column 107 and the third metal column 108 are located in the same plane and the angle between each of the metal columns is 120°. Each of the metal columns is respectively connected to the outer conductor 102 and the inner conductor 103. The heterogeneous reflector is composed of an inner reflector 104 and an outer reflector 105, and the inner reflector 104 is embedded in the center of the outer reflector 105.

[0006] In a possible implementation manner of the first aspect, there is a first reflection point on the microwave resonator, and the first reflection point is a spatial position where the first metal column 106 , the second metal column 107 , and the third metal column 108 are located.

[0007] Optionally, in another possible implementation of the first aspect, the microwave resonator includes a coaxial cable, the coaxial cable is composed of an outer conductor 102 and an inner conductor 103, the coaxial cable includes a first end and a second end, the first end is connected to the SMA connector 101, the first end is used for input and output of microwave signals, the second end is open-circuited, the open-circuited end is the open-circuited end of the coaxial cable, and the second reflection point of the microwave resonator is located at the open-circuited end of the coaxial cable.

[0008] Optionally, in another possible implementation manner of the first aspect, the distance between the first reflection point and the second reflection point in the X direction of the first coordinate axis is the resonant cavity length of the microwave resonator.

[0009] In the second aspect, an embodiment of the present application provides an application method of a sensor, the method being based on a first workpiece to be docked, a second workpiece to be docked, a high-precision alignment proximity sensor based on a heterogeneous reflective microwave resonator, a vector network analyzer and a coaxial cable connecting line. The microwave resonator and the heterogeneous reflective plate are respectively fixed on the first workpiece to be docked and the second workpiece to be docked on which an alignment proximity operation needs to be performed. The microwave resonator is connected to the vector network analyzer via a coaxial cable connecting line. The method comprises: obtaining a frequency response of the sensor according to the vector network analyzer, and demodulating the radial and axial relative positions between the open end of the coaxial cable in the microwave resonator and the heterogeneous reflective plate according to the frequency response.

[0010] In a possible implementation manner of the second aspect, the step of obtaining the frequency response of the sensor using a vector network analyzer includes:

[0011] A first frequency sweep microwave signal is sent out by a vector network analyzer and transmitted to a coaxial cable in a microwave resonator via a coaxial cable connecting line and an SMA connector. The first frequency sweep microwave signal is partially reflected at a first reflection point, and the remaining microwave signal is transmitted through the first reflection point and transmitted to a second reflection point where it is partially reflected. The partially reflected microwave signal will propagate back and forth multiple times in a resonant cavity between the first reflection point and the second reflection point, and will be partially transmitted and output each time it reaches the first reflection point. The microwave signal reflected for the first time at the first reflection point and all microwave signals transmitted thereafter have the same phase difference with each other, and the phase difference is determined by the length of the resonant cavity and the phase jump of the microwave signal at the reflection point.

[0012] The vector network analyzer receives a second frequency-sweeping microwave signal via a microwave signal through an SMA connector and a coaxial cable connection line, and obtains a frequency response of the microwave resonator based on the second frequency-sweeping microwave signal, wherein the second frequency-sweeping microwave signal is generated by reflecting the first frequency-sweeping microwave signal through a reflection point.

[0013] Optionally, in another possible implementation manner of the second aspect, the resonance intensity and the resonance frequency of the resonance valley in the frequency response of the microwave resonator depend on the reflection coefficient and the edge capacitance of the second reflection point, specifically including:

[0014] The total reflection coefficient R of the microwave resonator can be expressed as:

[0015]

[0016] Where Γ1 and Γ2 are the reflection coefficients of the first reflection point and the second reflection point, respectively. and are the phase jumps when the microwave signal is reflected at the first reflection point and the second reflection point, α is the transmission loss of the microwave signal in the coaxial cable, L is the length of the resonant cavity, and δ is the phase change of the microwave signal in a round trip in the resonant cavity, which can be expressed as:

[0017]

[0018] Where f is the frequency of the microwave signal, v is the microwave propagation speed, and the m-th order resonant frequency f of the microwave resonator can be obtained from equations (1) and (2): res,m for:

[0019]

[0020] in, It can be expressed as:

[0021]

[0022] Where C is the fringe capacitance of the open-circuit end of the coaxial cable, and Z0 is the characteristic impedance of the coaxial cable;

[0023] It can be seen from the above equations (1)-(4) that when the first reflection point and the resonant cavity are fixed, the resonance intensity and the resonance frequency of the resonance valley in the frequency response of the microwave resonator depend on the reflection coefficient and the edge capacitance of the second reflection point.

[0024] The present application provides a high-precision alignment proximity sensor based on a heterogeneous reflection microwave resonator, comprising: a sensor consisting of a microwave resonator and a heterogeneous reflection sheet, the microwave resonator consisting of an SMA connector, an outer conductor, an inner conductor, a first metal column, a second metal column, and a third metal column, and the heterogeneous reflection sheet consisting of an inner reflection sheet and an outer reflection sheet. Therefore, the high-precision alignment proximity sensor based on a heterogeneous reflection microwave resonator provided by the present application can measure the distance and deviation in the axial and radial dimensions without crosstalk based on a single sensor, and simultaneously realize dual-function sensing of alignment and proximity monitoring, thereby realizing high-precision alignment proximity sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 It is a structural schematic diagram of a high-precision alignment proximity sensor based on a heterogeneous reflective microwave resonator provided by an embodiment of the present application;

[0027] Figure 2 is a flow chart of a sensor application method provided by an embodiment of the present application;

[0028] Figure 3 is a schematic diagram of a scenario of an application method of a sensor provided in an embodiment of the present application;

[0029] Figure 4 is a schematic structural diagram of a two-dimensional alignment proximity sensor provided by an embodiment of the present application;

[0030] Figure 5 is a schematic diagram of frequency response under different experimental conditions provided in an embodiment of the present application;

[0031] Figure 6 This is a diagram of the training, verification, and testing results of an artificial neural network based on a multi-layer perceptron provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0033] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0034] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0035] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0036] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0037] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0038] The high-precision alignment proximity sensor based on a heterogeneous reflective microwave resonator and the application method of the sensor provided by the present application are described in detail below with reference to the accompanying drawings.

[0039] Figure 1 A schematic structural diagram of a high-precision alignment proximity sensor based on a heterogeneous reflective microwave resonator provided in an embodiment of the present application is shown.

[0040] like Figure 1 As shown, the high-precision alignment proximity sensor based on the heterogeneous reflection microwave resonator is composed of a microwave resonator and a heterogeneous reflection plate. The microwave resonator and the heterogeneous reflection plate are aligned on the same axis, and the distance between the microwave resonator and the heterogeneous reflection plate is a first preset distance; the microwave resonator is composed of an SMA connector 101, an outer conductor 102, an inner conductor 103, a first metal column 106, a second metal column 107, and a third metal column 108. The SMA connector 101 is connected to the outer conductor 102 and the inner conductor 103. The inner conductor 103 is placed inside the outer conductor 102. The hollow structure of the outer conductor 102 is filled with insulating dielectric material, and the hollow structure of the outer conductor 102 excluding the inner conductor 103 is filled with insulating dielectric material, the first metal column 106, the second metal column 107 and the third metal column 108 are located in the same plane and the angle between each metal column is 120°, and each metal column is respectively connected to the outer conductor 102 and the inner conductor 103; the heterogeneous reflector is composed of an inner reflector 104 and an outer reflector 105, the inner reflector 104 is embedded in the center of the outer reflector 105, and the inner reflector 104 and the outer reflector 105 have different dielectric constants.

[0041] Furthermore, in an embodiment of the present application, the microwave resonator further includes:

[0042] The first reflection point is composed of the spatial positions of the first metal column 106, the second metal column 107 and the third metal column 108. The reflection of the microwave signal by the first reflection point is achieved by the short circuit formed by the first metal column 106, the second metal column 107 and the third metal column 108 connecting the outer conductor 102 and the inner conductor 103.

[0043] Furthermore, in an embodiment of the present application, the microwave resonator further includes:

[0044] The coaxial cable is composed of an outer conductor 102 and an inner conductor 103. The coaxial cable includes a first end and a second end. The first end is connected to the SMA connector 101. The first end is used for input and output of microwave signals. The second end is open-circuited. The open-circuited end is the open-circuited end of the coaxial cable. The second reflection point of the microwave resonator is located at the open-circuited end of the coaxial cable. The microwave signal is reflected on the end surface of the open-circuited end of the coaxial cable to form the second reflection point of the microwave resonator.

[0045] Further, in the embodiment of the present application, the distance between the first reflection point and the second reflection point in the X direction of the first coordinate axis is the resonant cavity length of the microwave resonator.

[0046] Optionally, the first coordinate axis may be a spatial coordinate system.

[0047] Optionally, the outer conductor 101, the inner conductor 102, the first metal column 106, the second metal column 107, and the second metal column 108 may be made of stainless steel. In practical applications, other conductor materials may also be used according to actual requirements (such as high temperature, pressure resistance, wear resistance, etc.).

[0048] Optionally, the inner reflector 104 and the outer reflector 105 are made of stainless steel and rubber respectively. In practical applications, other two materials with different dielectric constants may also be used according to actual requirements.

[0049] The high-precision alignment proximity sensor based on heterogeneous reflection microwave resonator provided by the present application includes: the sensor is composed of a microwave resonator and a heterogeneous reflection plate, the microwave resonator is composed of an SMA connector, an outer conductor, an inner conductor, a first metal column, a second metal column, and a third metal column, and the heterogeneous reflection plate is composed of an inner reflection plate and an outer reflection plate. The high-precision alignment proximity sensor based on heterogeneous reflection microwave resonator provided by the present application can measure the distance and deviation in the axial and radial dimensions without crosstalk based on a single sensor, and realize dual-function sensing of alignment and proximity monitoring at the same time, thereby realizing high-precision alignment proximity sensing.

[0050] Figure 2 A schematic flow chart of a sensor application method provided in an embodiment of the present application is shown.

[0051] S201, according to the first frequency sweep microwave signal sent by the vector network analyzer, it is transmitted to the coaxial cable in the microwave resonator through the coaxial cable connecting line and the SMA connector, the first frequency sweep microwave signal is partially reflected at the first reflection point, the remaining microwave signal is transmitted through the first reflection point and transmitted to the second reflection point where it is partially reflected, the partially reflected microwave signal will propagate back and forth multiple times in the resonant cavity between the first reflection point and the second reflection point, and will be partially transmitted and output each time it reaches the first reflection point, the microwave signal reflected for the first time at the first reflection point and all microwave signals transmitted thereafter have the same phase difference with each other, and the phase difference is determined by the length of the resonant cavity and the phase jump of the microwave signal at the reflection point.

[0052] S202, receiving a second frequency-sweeping microwave signal according to the vector network analyzer via the microwave signal through the SMA connector and the coaxial cable connecting line, and obtaining a frequency response of the microwave resonator according to the second frequency-sweeping microwave signal, wherein the second frequency-sweeping microwave signal is generated by reflecting the first frequency-sweeping microwave signal through a reflection point.

[0053] S203, demodulating the relative positions of the open-circuit end of the coaxial cable in the microwave resonator and the heterogeneous reflector in radial and axial directions according to the frequency response.

[0054] It should be noted that if Figure 3 In the scenario diagram of the sensor application method shown, the sensor application method provided by the present application is based on a first workpiece to be docked 303, a second workpiece to be docked 304, a high-precision alignment proximity sensor based on a heterogeneous reflection microwave resonator (a microwave resonator 301 and a heterogeneous reflection plate 302), a vector network analyzer 305, and a coaxial cable connection line 306. The microwave resonator 301 and the heterogeneous reflection plate 302 are respectively fixed on the first workpiece to be docked 303 and the second workpiece to be docked 304 that need to perform an alignment proximity operation, and the microwave resonator 301 is connected to the vector network analyzer 305 via a coaxial cable connection line 306.

[0055] It should be noted that the first workpiece to be docked 303 and the second workpiece to be docked 304 are used to represent two target objects that need to be docked, and in actual situations, they may also be devices that need to be aligned and approached.

[0056] Optionally, the diameter of the inner reflector is equal to the diameter of the inner conductor, and the diameter of the outer reflector is equal to the diameter of the outer conductor.

[0057] Further, in the embodiment of the present application, the resonance intensity and the resonance frequency of the resonance valley in the frequency response of the microwave resonator depend on the reflection coefficient and the edge capacitance of the second reflection point, specifically including:

[0058] The total reflection coefficient R of the microwave resonator can be expressed as:

[0059]

[0060] Where Γ1 and Γ2 are the reflection coefficients of the first reflection point and the second reflection point, respectively. and are the phase jumps when the microwave signal is reflected at the first reflection point and the second reflection point, α is the transmission loss of the microwave signal in the coaxial cable, L is the length of the resonant cavity, and δ is the phase change of the microwave signal in a round trip in the resonant cavity, which can be expressed as:

[0061]

[0062] Where f is the frequency of the microwave signal, v is the microwave propagation speed, and the m-th order resonant frequency f of the microwave resonator can be obtained from equations (1) and (2): res,m for:

[0063]

[0064] in, It can be expressed as:

[0065]

[0066] Where C is the fringe capacitance of the open-circuit end of the coaxial cable, and Z0 is the characteristic impedance of the coaxial cable;

[0067] It can be seen from the above equations (1)-(4) that when the first reflection point and the resonant cavity are fixed, the resonance intensity and the resonance frequency of the resonance valley in the frequency response of the microwave resonator depend on the reflection coefficient and the edge capacitance of the second reflection point.

[0068] Optionally, in one embodiment, when the axial distance between the heterogeneous reflector 302 and the open end of the coaxial cable changes, the size of the edge capacitance is mainly affected, thereby changing the reflection coefficient and phase transition of the microwave signal at the second reflection point, causing changes in the resonance intensity and resonance frequency of the resonance valley in the frequency response of the microwave resonator 301.

[0069] Optionally, in one embodiment, when the radial deviation between the heterogeneous reflector 302 and the open end of the coaxial cable changes, the distribution and size of the edge capacitance will change simultaneously, thereby causing the reflection coefficient and phase jump of the microwave signal at the second reflection point to change differently from when the aforementioned axial distance changes, thereby causing the resonance intensity and resonance frequency of the resonance valley in the frequency response of the microwave resonator 301 to change differently.

[0070] Optionally, in one embodiment, when the open-circuit end of the coaxial cable in the microwave resonator 301 is close to the heterogeneous reflector, the edge capacitance is very sensitive to the axial distance and radial deviation, thereby achieving high-precision displacement sensing.

[0071] As a possible implementation, the present application provides a two-dimensional alignment proximity sensor as a specific embodiment of S201-S203 for detailed description. It should be noted that this embodiment is only exemplary. Figure 4 The structural schematic diagram of the two-dimensional alignment proximity sensor shown includes: a single metal column microwave resonator 401, a rectangular heterogeneous reflector 402, the single metal column microwave resonator 401 and the rectangular heterogeneous reflector 402 are aligned along the same axis, and the rectangular heterogeneous reflector 402 includes a stainless steel reflector 403 and a rubber reflector 404.

[0072] The 2D alignment proximity sensor is used to demonstrate displacement sensing along the X and Y directions;

[0073] In this embodiment, for ease of implementation, the single metal column microwave resonator 401 can omit the second metal column and the third metal column compared to the microwave resonator, and only requires a single metal column as the first reflection point, and the rest of the parts are completely the same. Therefore, the single metal column microwave resonator 401 is actually a special case of the microwave resonator, so the SMA connector, outer conductor, inner conductor, and first metal column will continue to be used for description in the following text.

[0074] In this embodiment, for ease of implementation, in the single metal column microwave resonator 401, the distance between the first reflection point and the second reflection point is 73.5 mm, the diameter of the first metal column is 3 mm, the inner conductor diameter 2a is 6 mm, the outer conductor inner diameter 2b is 14 mm, and the first metal column, inner conductor, and outer conductor are all made of stainless steel.

[0075] In this embodiment, for ease of implementation, air is provided between the outer conductor and the inner conductor, and the characteristic impedance of the coaxial cable in the single metal column microwave resonator 401 can be approximately expressed as:

[0076]

[0077] According to formula (5), it can be calculated that the characteristic impedance of the coaxial cable in this embodiment is about 50.78 ohms.

[0078] In actual implementation, other insulating dielectric materials may also be filled to improve the structural stability and sensing performance of the sensor, but the structural parameters of the outer conductor and the inner conductor need to be adjusted accordingly.

[0079] Assume that the point d=50 μm away from the center of the end face of the open-circuit end of the coaxial cable along the positive direction of X is the coordinate origin (0 μm, 0 μm, 0 μm).

[0080] For ease of implementation, a rectangular heterogeneous reflector 402 is used instead of a heterogeneous reflector. The rectangular heterogeneous reflector 402 is composed of a stainless steel reflector 403 and a rubber reflector 404 with different dielectric constants. The position of the rectangular heterogeneous reflector 402 is represented by the coordinates of the center point of a surface close to the open end of the coaxial cable in the single metal column microwave resonator 401.

[0081] The rectangular heterogeneous reflector 402 is placed at (50μm, 0μm, 0μm), and is displaced from -100μm to 100μm in the Y direction with a step of 10μm. The edge capacitance gradually increases, and the phase jump at the second reflection point decreases accordingly, resulting in a continuous decrease in the resonant frequency. The first-order resonance valley in its frequency response under different Y-direction displacements is as follows: Figure 5 (a) shown.

[0082] Similarly, the rectangular heterogeneous reflector 402 is placed at (50 μm, 0 μm, 0 μm), and is displaced from 0 μm to 100 μm in the X direction with a step of 10 μm. The edge capacitance gradually decreases, and the phase jump at the second reflection point increases accordingly, resulting in a continuous increase in the resonant frequency. The first-order resonance valley in its frequency response under different X-direction displacements is shown in FIG. Figure 5 (b) as shown.

[0083] The first-order resonant frequency of the two-dimensional alignment proximity sensor changes with the displacement of the rectangular heterogeneous reflector 402 from the origin along the Y direction as shown in FIG. Figure 5 As shown in (c), the first-order resonance frequency changes with the displacement of the rectangular heterogeneous reflector 402 from the origin along the X direction as shown in Figure 5 (d) as shown.

[0084] Displacement in both the X and Y directions will cause the resonant frequency to drift. The displacement in both dimensions cannot be demodulated simultaneously based on the resonant frequency alone. However, the displacement in the X and Y directions has different effects on the resonant intensity of each order of resonant valley.

[0085] The frequency response of the rectangular heterogeneous reflector 402 at (50 μm, -1300 μm, 0 μm) and (100 μm, 1300 μm, 0 μm) is as follows: Figure 5 As shown in (e), it can be seen that although the resonance frequencies of the two positions are almost the same, the resonance intensities of the resonance valleys of the two positions are different. Similarly, the frequency responses of the rectangular heterogeneous reflector 402 at (150 μm, -1500 μm, 0 μm) and (200 μm, 800 μm, 0 μm) are as follows: Figure 5 As shown in (f), it can be seen that although the resonance frequencies of each order at these two positions are almost the same, the resonance strength of each order resonance valley is also different. Therefore, the displacement in the two dimensions of the X direction and the Y direction can be simultaneously demodulated based on the resonance frequency and resonance strength of each order resonance valley.

[0086] The measured frequency response is processed by machine learning method, and the frequency response of the displacement of the rectangular heterogeneous reflector 402 in the X and Y directions is processed based on the multi-layer perceptron model. There are 7 hidden layers in total, the number of input layer nodes is equal to the number of data points of the S11 frequency response, and the number of output layer nodes is 2, namely the displacement in the X and Y directions.

[0087] The scatter plots of the predicted values ​​and true values ​​for multi-output regression prediction for the training data set, validation data set, and test data set (circles are true values, and boxes are predicted values) are shown below. Figure 6 As shown in Figures 6(a), 6(b) and 6(c), the predicted values ​​are almost consistent with the true values ​​in the range of 0μm to 450μm for displacement in the X direction and -1500μm to 1500μm for displacement in the Y direction, and the root mean square errors of the displacements in the X direction and Y direction are 0.4μm and 4.9μm, respectively, indicating that the present invention has a high-precision displacement demodulation effect.

[0088] The application method of the sensor provided in the present application, by using the high-precision alignment proximity sensor based on the heterogeneous reflection microwave resonator provided in the embodiment of the present application, can measure the distance and deviation in the axial and radial dimensions without crosstalk based on a single sensor, and simultaneously realize dual-function sensing of alignment and proximity monitoring, thereby realizing high-precision alignment proximity sensing.

[0089] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0090] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0091] In the embodiments provided in the present application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0092] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0093] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A high-precision alignment proximity sensor based on a heterogeneous reflective microwave resonator, characterized in that: include: The sensor is composed of a microwave resonator and a heterogeneous reflector. The microwave resonator and the heterogeneous reflector are aligned on the same axis. The distance between the microwave resonator and the heterogeneous reflector is a first preset distance. The microwave resonator is composed of an SMA connector 101, an outer conductor 102, an inner conductor 103, a first metal column 106, a second metal column 107, and a third metal column 108. The SMA connector 101 is connected to the outer conductor 102 and the inner conductor 103. The inner conductor 103 is placed on the outer conductor 102. An insulating dielectric material is filled in the internal hollow structure, and in the hollow structure of the outer conductor 102 excluding the inner conductor 103, the first metal column 106, the second metal column 107 and the third metal column 108 are located in the same plane and the angle between each of the metal columns is 120°, and each of the metal columns is respectively connected to the outer conductor 102 and the inner conductor 103; the heterogeneous reflector is composed of an inner reflector 104 and an outer reflector 105, and the inner reflector 104 is embedded in the center of the outer reflector 105.

2. The sensor according to claim 1, characterized in that There is a first reflection point on the microwave resonator, and the first reflection point is the spatial position where the first metal column 106 , the second metal column 107 , and the third metal column 108 are located.

3. The sensor according to claim 2, characterized in that The microwave resonator includes a coaxial cable, which is composed of the outer conductor 102 and the inner conductor 103. The coaxial cable includes a first end and a second end. The first end is connected to the SMA connector 101. The first end is used for input and output of microwave signals. The second end is open-circuited. The open-circuited end is the open-circuited end of the coaxial cable. The second reflection point of the microwave resonator is located at the open-circuited end of the coaxial cable.

4. The sensor according to claim 3, characterized in that The distance between the first reflection point and the second reflection point in the X direction of the first coordinate axis is the resonant cavity length of the microwave resonator.

5. A sensor application method, characterized in that: The method is based on the high-precision alignment proximity sensor based on the heterogeneous reflective microwave resonator, a first workpiece to be docked, a second workpiece to be docked, a vector network analyzer and a coaxial cable connection line. The microwave resonator and the heterogeneous reflective sheet are respectively fixed on the first workpiece to be docked and the second workpiece to be docked on which an alignment proximity operation needs to be performed. The microwave resonator is connected to the vector network analyzer through the coaxial cable connection line. The method includes: The frequency response of the sensor is obtained by a vector network analyzer, and the relative positions of the open-circuit end of the coaxial cable in the microwave resonator and the heterogeneous reflector in radial and axial directions are demodulated according to the frequency response.

6. The method according to claim 5, characterized in that The step of obtaining the frequency response of the sensor according to a vector network analyzer comprises: The first frequency sweep microwave signal emitted by the vector network analyzer is transmitted to the coaxial cable in the microwave resonator through the coaxial cable connecting line and the SMA connector, the first frequency sweep microwave signal is partially reflected at the first reflection point, the rest of the microwave signal is transmitted through the first reflection point and transmitted to the second reflection point where it is partially reflected, the partially reflected microwave signal will propagate back and forth multiple times in the resonant cavity between the first reflection point and the second reflection point, and will be partially transmitted and output each time it reaches the first reflection point, the microwave signal reflected for the first time at the first reflection point and all the microwave signals transmitted thereafter have the same phase difference with each other, and the phase difference is determined by the length of the resonant cavity and the phase jump of the microwave signal at the reflection point; The vector network analyzer receives a second swept-frequency microwave signal via the microwave signal through the SMA connector and the coaxial cable connecting line, and obtains the frequency response of the microwave resonator based on the second swept-frequency microwave signal, wherein the second swept-frequency microwave signal is generated by reflecting the first swept-frequency microwave signal through the reflection point.

7. The method according to claim 6, characterized in that The resonance intensity and the resonance frequency of the resonance valley in the frequency response of the microwave resonator depend on the reflection coefficient and the edge capacitance of the second reflection point, and specifically include: The total reflection coefficient R of the microwave resonator can be expressed as: Wherein, Γ1 and Γ2 are the reflection coefficients of the first reflection point and the second reflection point respectively, and are the phase jumps when the microwave signal is reflected at the first reflection point and the second reflection point, respectively; α is the transmission loss of the microwave signal in the coaxial cable; L is the length of the resonant cavity; δ is the phase change of the microwave signal in a round trip propagation in the resonant cavity, which can be expressed as: Wherein, f is the frequency of the microwave signal, v is the microwave propagation speed, and the m-th order resonance frequency f of the microwave resonator can be obtained from equations (1) and (2): res,m for: in, It is expressed as: Wherein, C is the fringe capacitance of the open-circuit end of the coaxial cable, and Z0 is the characteristic impedance of the coaxial cable; It can be seen from the above formulas (1)-(4) that, when the first reflection point and the resonant cavity are fixed, the resonance intensity and the resonant frequency of the resonance valley in the frequency response of the microwave resonator depend on the reflection coefficient and the edge capacitance of the second reflection point.

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