A method for measuring flow field surface pressure based on reflection spectroscopy

Abstract

The invention provides a flow field surface pressure measurement method based on reflection spectrum, relates to the field of high-speed flow field pressure measurement, and solves the problems of low spatial resolution, destruction of flow field structure, weak anti-electromagnetic interference ability and poor stability of the existing high-speed flow field pressure measurement technology. The method comprises: designing a one-dimensional grating waveguide structure device based on grating anomaly in grating theory, preparing the designed one-dimensional grating waveguide structure device; calibrating the pressure of the prepared one-dimensional grating waveguide structure device, placing it in a high-speed flow field test pressure measurement system after the calibration, and measuring the flow field pressure on the model surface through the reflection spectrum of the one-dimensional grating waveguide structure device; the invention designs a grating structure through the pressure sensitive mechanism of a flexible grating structure, realizes real-time measurement of the high-speed flow field pressure through the reflection spectrum frequency shift, has small interference to the flow field, small environmental electromagnetic interference, simple device, and low measurement and maintenance cost.

Description

Technical Field

[0001] This invention relates to the field of high-speed flow field pressure measurement, and more specifically to a method for measuring surface pressure in a flow field based on reflection spectroscopy. Background Technology

[0002] With the development of aerospace engineering, the demand for accurate measurement of the flow field pressure characteristics of high-speed aircraft is increasing. This is not only crucial for the design and optimization of aircraft, but also fundamental to ensuring their performance and safety. However, traditional pressure measurement techniques, such as the pressure orifice method, pressure sensor method, and pressure-sensitive paint (PSP) method, have revealed a series of technical bottlenecks and limitations when faced with complex and variable high-speed flow field environments.

[0003] Pressure measurement via borehole method: This method involves drilling holes in an aircraft model and connecting pipes to measure pressure. However, this method disrupts the model's original surface structure, potentially altering hydrodynamic properties and affecting measurement accuracy. Furthermore, the limited number of boreholes fails to provide sufficient spatial resolution, and airflow conduction losses and signal hysteresis within the pipes limit the real-time performance and accuracy of the data.

[0004] Pressure sensor technology: Using microelectromechanical systems (MEMS) technology to mount sensors on the model surface can improve measurement accuracy, but the high cost, complex structure, and potential electromagnetic interference problems in the measurement process, coupled with the existence of measurement blind spots, limit the method's ability to fully cover high-speed flow fields.

[0005] Pressure-sensitive paint (PSP) technology: Although PSP offers high spatial resolution and minimal flow field disturbance, under high-speed flow conditions, the adverse pressure gradient formed on the model surface makes it difficult for oxygen molecules to reach the near-wall region, causing uneven oxygen distribution and resulting in measurement errors. PSP is also limited by issues such as formulation stability, fluorescence time, uniformity of coating thickness, and short effective measurement time. These factors reduce the accuracy, reliability, and repeatability of measurements, making it unsuitable for the detailed research needs of high-speed flow fields.

[0006] Given the shortcomings and deficiencies of existing technologies, there is an urgent need to develop a new pressure measurement technology to overcome the above challenges and meet the high requirements of high-speed aircraft research for pressure measurement in strong three-dimensional, unsteady flow fields. Summary of the Invention

[0007] Based on the current state of the technology, the purpose of this invention is to solve the problems of low spatial resolution, damage to the flow field structure, weak resistance to electromagnetic interference, and poor stability of existing high-speed flow field pressure measurement technologies. Therefore, a flow field surface pressure measurement method based on reflection spectrum is proposed. This method uses flexible materials to fabricate pressure-sensitive grating devices, designs the grating structure based on the pressure-sensitive mechanism of the flexible grating structure, and achieves real-time measurement of high-speed flow field pressure by shifting the frequency of the reflection spectrum. This invention has low interference with the flow field, low environmental electromagnetic interference, simple device, and low measurement and maintenance costs.

[0008] The present invention employs the following technical solutions to achieve its objective:

[0009] A method for measuring surface pressure in a flow field based on reflectance spectroscopy, the method comprising the following steps:

[0010] S1. Based on the grating anomalous phenomenon in grating theory, design a one-dimensional grating waveguide structure device;

[0011] S2. Fabricate the designed one-dimensional grating waveguide structure device;

[0012] S3. Perform pressure calibration on the prepared one-dimensional grating waveguide structure device. After calibration, place it into the test pressure measurement system of high-speed flow field. Measure the flow field pressure on the model surface through the reflection spectrum of the one-dimensional grating waveguide structure device.

[0013] Furthermore, in step S1, the designed one-dimensional grating waveguide structure device includes a three-layer grating waveguide structure, which consists of a grating layer, a dielectric layer, and a substrate from top to bottom; for the grating layer, it is designed as a one-dimensional grating structure arranged along the length direction of the one-dimensional grating waveguide structure device.

[0014] Furthermore, the grating layer is made of flexible PMDS material, while the dielectric layer and substrate are both made of non-absorbing dielectric materials. When the structural parameters of the grating layer made of flexible PMDS material change, the resonant wavelength changes, resulting in a resonant anomaly, which causes the optical field energy to be redistributed, thereby changing the reflection spectrum of the one-dimensional grating waveguide structure device.

[0015] Furthermore, in step S2, when fabricating the one-dimensional grating waveguide structure device, the substrate non-absorbing dielectric material is a silicon dioxide substrate; the fabrication process adopts standard cleanroom semiconductor micro-nano fabrication technology.

[0016] Furthermore, in step S3, during pressure calibration, incident light is irradiated onto the one-dimensional grating waveguide structure device, and the projection direction of the incident light on the horizontal plane is the same as the grating period length direction of the grating layer with the one-dimensional grating structure in the one-dimensional grating waveguide structure device; a pressure value is smoothly applied to the one-dimensional grating waveguide structure device, and the shift parameters of the reflection spectrum of the incident light after passing through the one-dimensional grating waveguide structure device under different pressure values ​​are recorded as calibration results for different pressure values.

[0017] Furthermore, the high-speed flow field test pressure measurement system includes a spectrometer, a reflector, an airflow space, and a detector. During flow field pressure measurement, the aircraft model is placed in the airflow space, and the calibrated one-dimensional grating waveguide structure is fixed to the surface of the aircraft model. The spectrometer emits incident light with preset parameters, and the reflector adjusts the horizontal projection direction and incident angle of the incident light to illuminate the one-dimensional grating waveguide structure. The detector records the reflection spectrum generated after the incident light passes through the one-dimensional grating waveguide structure, and compares this spectrum with the calibration results to determine the magnitude of the surface pressure of the aircraft model under the current airflow space, thus completing the flow field pressure measurement.

[0018] In summary, due to the adoption of this technical solution, the beneficial effects of this invention are as follows:

[0019] The one-dimensional grating waveguide structure device fabricated by this invention can be closely attached to the model surface without damaging the original structure of the model, avoiding interference with the flow field characteristics and improving the accuracy and reliability of measurements. Utilizing the frequency shifting principle of the grating structure, this invention can achieve rapid response and real-time monitoring of pressure changes in high-speed flow fields, overcoming the signal delay and attenuation problems in traditional methods and improving the real-time performance and effectiveness of the data.

[0020] The grating device's operating mechanism is unaffected by electromagnetic fields, enabling the invention to maintain stable performance even in complex electromagnetic testing environments, ensuring the purity and consistency of measurement data. Furthermore, compared to traditional MEMS sensor technology and PSP technology, the measurement process of this invention is simpler, eliminating the need for complex piping or expensive material formulations, significantly reducing the purchase and maintenance costs of related equipment, and also reducing operational complexity.

[0021] Flexible grating devices can be flexibly deployed anywhere on the model, including surfaces with complex shapes or high curvature, enabling targeted pressure measurements and achieving high-density, high-spatial-resolution distributed pressure measurement. Therefore, they are particularly suitable for analyzing the complex characteristics of strong three-dimensional, unsteady flow fields. The measurement technology of this invention is also easily integrated with existing experimental platforms, possesses good scalability, and allows for flexible adjustment of the measurement range and accuracy according to different measurement needs, providing strong technical support for future flow field research on high-speed aircraft. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall process of the method of the present invention;

[0023] Figure 2 This is a schematic diagram of the one-dimensional grating waveguide structure device in this invention;

[0024] Figure 3 This is a schematic diagram of the cross-section and design parameters of the one-dimensional grating waveguide structure device in this invention;

[0025] Figure 4 This is a schematic diagram of the reflection spectrum of the device simulated in this invention under different pressures;

[0026] Figure 5 This is one of the schematic diagrams showing the variation of the resonant wavelength and peak value of the reflection spectrum with pressure;

[0027] Figure 6 This is the second schematic diagram showing the variation of the resonant wavelength and peak value of the reflection spectrum with pressure.

[0028] Figure 7 This is a schematic diagram illustrating the fabrication of the one-dimensional grating waveguide structure device in this invention;

[0029] Figure 8 This is a schematic diagram of the experimental pressure measurement system for high-speed flow fields in this invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] Example 1

[0033] like Figure 1 As shown, a method for measuring surface pressure in a flow field based on reflectance spectra is described in the following steps:

[0034] S1. Based on the grating anomalous phenomenon in grating theory, design a one-dimensional grating waveguide structure device;

[0035] S2. Fabricate the designed one-dimensional grating waveguide structure device;

[0036] S3. Perform pressure calibration on the prepared one-dimensional grating waveguide structure device. After calibration, place it into the test pressure measurement system of high-speed flow field. Measure the flow field pressure on the model surface through the reflection spectrum of the one-dimensional grating waveguide structure device.

[0037] This embodiment will provide a detailed explanation of the design process for the one-dimensional grating waveguide structure device in step S1. First, a grating (also known as a diffraction grating) is an optical element with a periodic structure that modulates the amplitude or phase of incident light through periodic changes in the refractive index field.

[0038] In grating theory, the phenomenon where the diffraction efficiency of a grating changes abruptly with variations in the incident angle or wavelength is called grating anomalous phenomenon. Based on this phenomenon, this embodiment designs a one-dimensional grating waveguide structure device with a three-layer grating waveguide structure. For example... Figure 2 As shown, the one-dimensional grating waveguide structure device consists of a grating layer, a dielectric layer, and a substrate from top to bottom; the grating layer is designed as a one-dimensional grating structure arranged along the length of the one-dimensional grating waveguide structure device.

[0039] In this embodiment, the grating layer is made of the flexible material PMDS when designing the one-dimensional grating waveguide structure. PMDS is a highly elastic and transparent rubber material with an operating temperature between -50 and 200°C. It has a relatively low Young's modulus and is therefore commonly used as a stretchable substrate material. The flexible PMDS used in this embodiment has a Young's modulus of 750 kPa and a Poisson's ratio of 0.49. For the dielectric layer and substrate, both are made of non-absorbing dielectric materials, which have a larger Young's modulus than the flexible PMDS and can therefore be considered as non-stretchable materials.

[0040] As can be seen from the well-known intrinsic equations of planar waveguide modes corresponding to grating waveguides in this field, when the structural parameters of the grating layer using flexible PMDS material change, the resonant wavelength changes, resulting in a resonance anomaly. This causes a redistribution of optical field energy, thereby altering the reflection spectrum of the one-dimensional grating waveguide structure device. This is the theoretical basis for the design process of this embodiment.

[0041] Therefore, the design process of the one-dimensional grating waveguide structure device in this embodiment is as follows:

[0042] like Figure 3 As shown, the refractive index of the grating layer is determined. The refractive index of the dielectric layer material and the refractive index of the substrate material For a grating layer with a one-dimensional grating structure, determine the grating period. Fill factor And the center wavelength of the incident light required for the grating layer to operate is denoted as The angle of incidence is denoted as Let the direction of the projection of the incident light onto the horizontal plane be the same as the direction of the grating period length of the one-dimensional grating structure.

[0043] Determine the thickness of the grating layer and the thickness of the dielectric layer Simultaneously, constraints are set regarding the refractive index: the refractive index of the dielectric layer material. Simultaneously, the material refractive index is greater than that of the grating layer. and the refractive index of the substrate material Then, based on planar waveguide theory, the characteristic equations of one-dimensional grating waveguide structures in TE and TM modes are derived as follows:

[0044]

[0045]

[0046] In the two characteristic equations, there are three intermediate parameters. , , ;in For diffraction orders, Let be the incident light wave vector. The propagation constant is denoted by ; when the grating layer's ... The propagation constant of an evanescent wave and the first of the dielectric layers Propagation constant of each waveguide mode When matched, the first The evanescent wave resonates with the guided mode in the dielectric layer, effectively coupling the energy of the incident light into the waveguide mode, thus yielding the following equation:

[0047]

[0048] In the formula, This enables the design of one-dimensional grating waveguide structure devices.

[0049] The TE (transverse electric mode) and TM (transverse magnetic mode) modes of waveguides mentioned in the design process are two fundamental modes of electromagnetic wave propagation in waveguide structures. The TE mode is characterized by the electric field being confined within the cross-section of the waveguide, while the magnetic field has components both in the cross-section and parallel to the propagation direction. The TM mode is characterized by the magnetic field being confined within the cross-section of the waveguide, while the electric field has components both in the cross-section and parallel to the propagation direction.

[0050] The constant matching mentioned in the design process causes guided mode resonance, a phenomenon known as guided mode resonance, which is a type of grating anomaly. The principle behind this phenomenon is the coupling between the grating diffracted waves and the leaky waves supported by the waveguide. It can be understood as a redistribution of energy in the optical field when the phase of certain diffracted waves in the grating matches the phase of the guided mode supported by the waveguide. Guided mode resonance in gratings is a very special optical phenomenon, characterized by narrow bandwidth, high diffraction efficiency, wavelength sensitivity, and angle sensitivity. It is often used in the design of high reflectivity detectors, refractive index detectors, and narrowband filters; this embodiment also utilizes it in its design and measurement scenarios.

[0051] Based on the design process of a one-dimensional grating waveguide structure device, as a preferred embodiment, the thin-film anti-reflection layer design principle is adopted. The grating layer and dielectric layer are designed as thin-film structures, and the optical thickness of each thin film is selected to be equal to the center wavelength of the incident light. ,Right now , is the equivalent refractive index of the grating layer.

[0052] Based on this design and optimization, the specific design parameters of the three-layer grating waveguide structure of the optimal one-dimensional grating waveguide structure device determined in this embodiment are as follows: incident light center wavelength. Furthermore, TE polarization is employed, meaning the electric field direction is parallel to the grating strips; the refractive index of the grating layer material is... ,thickness The refractive index of the dielectric layer material ,thickness The refractive index of the substrate material ; grating period of the grating layer Fill factor .

[0053] Based on the above design parameters, the experimental results of the relevant data in this embodiment are described as follows.

[0054] Figure 4 This refers to the reflection spectrum of the device's grating structure under different pressures during the simulation. Figure 4 It can be seen that at 0 kPa pressure and 0° incident angle, the reflectance spectrum is as follows: There is a resonance peak with strong reflection at that point; when the incident angle increases to 3°, The resonance peak at that location splits into two at... and The two resonance peaks at the incident angle. The splitting of the reflection peak with the incident angle can be explained by grating theory. From the formula obtained from the energy coupling of the incident light at resonance mentioned above, it can be seen that at normal incidence, Leakage wave corresponding to the evanescent wave and Leakage wave corresponding to the evanescent wave When they overlap and cannot be distinguished, they appear as a single, highly reflective resonance peak; under oblique incidence, Leakage wave corresponding to the evanescent wave , The peaks no longer overlap, and at this point, they appear as two highly reflective peaks. Therefore, the two resonance peaks that appear under oblique incidence conditions represent two different leakage wave modes.

[0055] like Figure 4 As shown, when the pressure increases from 0 kPa to 200 kPa, the resonant modes in regions 1 and 2 of the figure both redshift with increasing pressure, but the resonant intensity in region 1 decreases with increasing pressure, while the resonant intensity in region 2 remains unchanged. This is because, with the same incident angle, wavelength, and period, the resonant mode increases with the increase of the grating's equivalent refractive index. In the one-dimensional grating waveguide structure device designed in this embodiment, the initial grating height is i.e., the thickness of the grating layer. Width, i.e., grating period Multiply by fill factor for As pressure increases, the equivalent refractive index of the grating layer increases with its width, resulting in a redshift of the corresponding resonance peak. The different variations in resonance intensity with structural changes are due to the different sensitivities of the diffraction efficiencies of the two modes to the grating height and width.

[0056] Figure 5 , Figure 6 The diagram illustrates the variation of the resonance wavelength and peak value of the reflection spectrum with pressure, representing different wavelength ranges. As shown in the figure, the wavelengths of the two resonance peaks increase approximately linearly with pressure. When the pressure increases from 0 kPa to 200 kPa, Figure 5 The resonant wavelength in Move to Wavelength shift ; Figure 6 Resonant wavelength in From moving Wavelength shift Furthermore, the resonance peak values ​​of the two resonance modes exhibit different relationships with pressure, due to the varying sensitivities of the different modes to grating height and width.

[0057] Example 2

[0058] Based on Example 1, this example provides a detailed description of the fabrication process of the designed one-dimensional grating waveguide structure device, corresponding to step S2 in the method. In fabricating the one-dimensional grating waveguide structure device, a silicon dioxide substrate is used as the non-absorbing dielectric material; the fabrication process employs standard cleanroom semiconductor micro / nano fabrication technology.

[0059] Semiconductor micro / nano fabrication processes in cleanrooms are highly precise techniques used to manufacture electronic components at the micron and nanometer scale, such as integrated circuits, sensors, actuators, and microelectromechanical systems (MEMS). These processes are performed in a clean environment to ensure that products are free from contamination, thereby achieving the required performance and reliability. The one-dimensional grating waveguide structure device of this embodiment is also particularly suitable for fabrication using this process.

[0060] In this embodiment, as Figure 7 As shown, the fabrication process of a one-dimensional grating waveguide structure device includes the following steps:

[0061] S21. A dielectric layer is prepared on a silicon dioxide substrate using electron beam sputtering.

[0062] S22. Mix the basic components of flexible material PMDS with curing agent in a ratio of 10:1 to obtain PMDS prepolymer; uniformly drop the PMDS prepolymer onto the dielectric layer and spin coat it evenly using a spin coater; then heat and cure it on a constant temperature table at 80℃ to obtain PDMS film layer.

[0063] S23. Using electron beam lithography, a pattern mask is made on the PDMS thin film layer, and then plasma etching, electron beam sputtering and metal lift-off methods are used in sequence to obtain a PDMS grating pattern with a one-dimensional grating structure, which serves as the grating layer.

[0064] S24. Using the dicing method, a one-dimensional grating waveguide structure device is obtained, completing the fabrication process.

[0065] Example 3

[0066] Based on any of the above embodiments, this embodiment provides a detailed description of step S3 in the method. During pressure calibration, incident light is irradiated onto the one-dimensional grating waveguide structure device, ensuring that the projection direction of the incident light onto the horizontal plane is the same as the grating period length direction of the grating layer with the one-dimensional grating structure in the one-dimensional grating waveguide structure device. A pressure value is smoothly applied to the one-dimensional grating waveguide structure device, and the shift parameters of the reflection spectrum of the incident light after passing through the one-dimensional grating waveguide structure device under different pressure values ​​are recorded as calibration results for different pressure values.

[0067] like Figure 8As shown, the high-speed flow field test pressure measurement system includes a spectrometer, a reflector, an airflow space, and a detector. During flow field pressure measurement, the aircraft model is placed in the airflow space, and a calibrated one-dimensional grating waveguide structure is fixed to the surface of the aircraft model. The spectrometer emits incident light with preset parameters, and the reflector adjusts the horizontal projection direction and incident angle of the incident light to illuminate the one-dimensional grating waveguide structure. The detector records the reflection spectrum generated after the incident light passes through the one-dimensional grating waveguide structure and compares it with the calibration results to determine the magnitude of the surface pressure of the aircraft model under the current airflow space, thus completing the flow field pressure measurement.

[0068] In summary, the method of this invention can perform non-invasive measurements by closely fitting the model surface without interfering with the flow field characteristics. It also has advantages such as strong anti-interference, high stability, and low maintenance cost, providing strong technical support for the flow field research of future high-speed aircraft.

Claims

1. A method for measuring flow field surface pressure based on reflection spectroscopy, characterized in that: The method comprises the following steps: S1. Design one-dimensional grating waveguide structure device based on grating anomaly phenomenon in grating theory; S2. Prepare the designed one-dimensional grating waveguide structure device; S3, calibrating the pressure of the prepared one-dimensional grating waveguide structure device, and placing it in a high-speed flow field test pressure measurement system after the calibration; measuring the flow field pressure on the model surface through the reflection spectrum of the one-dimensional grating waveguide structure device; In step S1, the designed one-dimensional grating waveguide structure device includes three layers of grating waveguide structure, which are a grating layer, a dielectric layer and a substrate from top to bottom; the grating layer is designed to be a one-dimensional grating structure arranged along the length direction of the one-dimensional grating waveguide structure device; The material of the grating layer is the flexible material PMDS, and the materials of the dielectric layer and the substrate are both non-absorption dielectric materials; when the structural parameters of the grating layer using the flexible material PMDS change, the resonance wavelength changes, resulting in a resonance anomaly, so that the light field energy is redistributed, thereby changing the reflection spectrum of the one-dimensional grating waveguide structure device; In step S2, when preparing a one-dimensional grating waveguide structure device, the non-absorbing dielectric material of the substrate is a silicon dioxide substrate; The preparation process adopts standard clean room semiconductor micro-nano processing technology.

2. The flow field surface pressure measurement method based on reflection spectroscopy according to claim 1 is characterized in that: The design process of one-dimensional grating waveguide structure device is as follows: Determine the material refractive index of the grating layer , the material refractive index of the dielectric layer and the refractive index of the substrate material ; For a grating layer with a one-dimensional grating structure, determine the grating period , Fill Factor , and the central wavelength of the incident light required for the grating layer to work is recorded as , the incident angle is recorded as , so that the projection direction of the incident light on the horizontal plane is the same as the grating period length direction of the one-dimensional grating structure; Determine the thickness of the grating layer and the thickness of the dielectric layer , and set constraints on the refractive index: the material refractive index of the dielectric layer At the same time, it is greater than the refractive index of the material of the grating layer and the refractive index of the substrate material ; Then, based on the slab waveguide theory, the characteristic equations of the one-dimensional grating waveguide structure device in TE and TM modes are obtained: In the two characteristic equations, the three intermediate parameters , , ;in is the diffraction order, is the incident light wave vector, is the propagation constant; when the first Propagation constant of the evanescent wave and the dielectric layer The propagation constant of the waveguide mode When matching, The evanescent wave resonates with the guided mode in the dielectric layer, so that the energy of the incident light is effectively coupled to the waveguide mode, thereby obtaining the following formula: In the formula, ; Thus, the design of one-dimensional grating waveguide structure devices is realized.

3. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 2, characterized in that: Based on the design process of one-dimensional grating waveguide structure devices, the thin film anti-reflection layer design principle is adopted to design the grating layer and the dielectric layer into a thin film structure, and the optical thickness of the grating layer and the dielectric layer is selected to be the central wavelength of the incident light. ,Right now , is the equivalent refractive index of the grating layer.

4. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 3, characterized in that: The specific design parameters of the three-layer grating waveguide structure of the one-dimensional grating waveguide structure device are: the central wavelength of the incident light , and TE polarization is used; the refractive index of the material of the grating layer ,thickness ; Material refractive index of the dielectric layer ,thickness ; Refractive index of the substrate material ; Grating period of the grating layer , filling factor .

5. The flow field surface pressure measurement method based on reflection spectroscopy according to claim 1 is characterized in that: The preparation process of a one-dimensional grating waveguide structure device includes the following steps: S21, preparing a dielectric layer on a silicon dioxide substrate by electron beam sputtering; S22, mixing the basic components of the flexible material PMDS and the curing agent in a ratio of 10:1 to obtain a PMDS prepolymer; uniformly dropping the PMDS prepolymer on the dielectric layer, and evenly spin coating it using a coating machine, and then heating and curing it on a constant temperature table at a temperature of 80° C. to obtain a PDMS thin film layer; S23, using an electron beam lithography method to perform a pattern mask on the PDMS thin film layer, and then using plasma etching, electron beam sputtering and metal stripping methods in sequence to obtain a PDMS grating pattern with a one-dimensional grating structure as a grating layer; S24. Using a slicing method, a one-dimensional grating waveguide structure device is obtained to complete the preparation process.

6. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 1, characterized in that: In step S3, when performing pressure calibration, the incident light is made to illuminate the one-dimensional grating waveguide structure device, so that the projection direction of the incident light on the horizontal plane is the same as the grating period length direction of the grating layer with a one-dimensional grating structure in the one-dimensional grating waveguide structure device; the pressure value is smoothly applied to the one-dimensional grating waveguide structure device, and the movement parameters of the reflection spectrum of the incident light after passing through the one-dimensional grating waveguide structure device at different pressure values ​​are recorded respectively as the calibration results of different pressure values.

7. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 6, characterized in that: The experimental pressure measurement system of the high-speed flow field includes a spectrometer, a reflector, an airflow space and a detector. When measuring the flow field pressure, the aircraft model is placed in the airflow space, and the calibrated one-dimensional grating waveguide structure device is fixed on the surface of the aircraft model. The spectrometer is used to emit incident light with preset parameters, and the horizontal plane projection direction and the incident angle of the incident light are adjusted through the reflector so that the incident light illuminates the one-dimensional grating waveguide structure device. The detector is used to record the reflection spectrum generated by the incident light after passing through the one-dimensional grating waveguide structure device, and compared with the calibration result, the surface pressure of the flow field of the aircraft model in the current airflow space is obtained, and the flow field pressure measurement is completed.

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