Sub-micron lunar dust detection device and method based on si3n4 metasurface

Abstract

This invention proposes a submicron lunar dust detection device and method based on a Si3N4 metasurface, belonging to the field of lunar exploration engineering technology. It solves the technical challenge of achieving high-precision, non-contact, real-time detection of submicron lunar dust in the extreme lunar environment. It includes a laser excitation unit, a signal detection unit, a Si3N4 metasurface sensing module, and a temperature control and data analysis processing module. The Si3N4 metasurface sensing module comprises, from top to bottom, a dust-proof coating, a Si3N4 nanostructure layer, an Au reflection modulation layer, and a single-crystal silicon substrate layer, used to sense lunar dust adhesion and generate changes in optical signals. The temperature control and data analysis processing module includes a temperature control unit, a data processing and analysis unit, and a housing. The data processing and analysis unit is installed inside the housing and has a built-in pre-calibrated model for retrieving lunar dust parameters based on the changes in optical signals. It is mainly used for detecting the concentration and particle size parameters of submicron lunar dust in the extreme lunar environment.

Description

Technical Field

[0001] This invention relates to the field of lunar exploration engineering technology, and in particular to a submicron lunar dust detection device and method based on a Si3N4 metasurface. Background Technology

[0002] In lunar exploration missions, submicron-sized (particle size <1μm) lunar dust, due to its large specific surface area, easy suspension, and strong adsorption, has become a key factor threatening the normal operation of exploration equipment: it can easily intrude into the mechanical gaps of the probe, causing component wear and jamming; it can adhere to the surface of optical lenses or energy transmission devices, reducing imaging accuracy and laser energy transmission efficiency; and long-term suspension may also pose a potential risk to the health of astronauts in manned exploration missions.

[0003] Existing detection technologies have significant limitations: contact sampling methods (such as optical microscopy) cannot provide in-situ real-time monitoring and disrupt the original state of lunar dust; laser scattering methods lack sensitivity to submicron particles and are easily affected by background radiation; while mass spectrometry can analyze components, the equipment is bulky and power-intensive, making it difficult to adapt to small lunar platforms. Therefore, there is an urgent need for a submicron lunar dust detection solution that is highly sensitive, resistant to extreme environments, non-contact, and miniaturized.

[0004] Silicon nitride (Si3N4) materials possess excellent resistance to high and low temperatures (-200℃~1200℃), radiation resistance, and low optical loss, making them ideal materials for lunar environments. Bound states in the continuous spectrum (BIC), as a special electromagnetic mode of metasurfaces, have extremely high quality factors (Q value ≥ 10³), and their resonance peaks are highly sensitive to changes in the environmental dielectric constant. Summary of the Invention

[0005] To address the technical challenge of achieving high-precision, non-contact, real-time detection of submicron lunar dust in the extreme lunar environment, this invention proposes a submicron lunar dust detection device and method based on a Si3N4 metasurface. This method combines the material advantages of Si3N4 with the high-sensitivity mechanism of the Bipolar Interval Conversion (BIC). Utilizing the high Q-value (≥10³) resonance mode of the Si3N4 metasurface's BIC, the minute dielectric constant changes caused by lunar dust adhesion are transformed into significant resonance peak wavelength shifts. By detecting this optical signal and inverting it through a pre-calibrated model, the concentration and particle size distribution of the lunar dust can be obtained, providing a novel solution for detecting submicron lunar dust in the extreme lunar environment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a submicron lunar dust detection device based on a Si3N4 metasurface, comprising a laser excitation unit, a signal detection unit, a Si3N4 metasurface sensing module, and a temperature control and data analysis and processing module. The laser excitation unit and the signal detection unit are both disposed above the Si3N4 metasurface sensing module, and the temperature control and data analysis and processing module is installed on the bottom surface of the Si3N4 metasurface sensing module. The laser excitation unit is used to excite a light beam, which is incident at a 45° angle onto the center region of the top surface of the Si3N4 metasurface sensing module. The signal detection unit is used to collect the reflected optical signal; The Si3N4 metasurface sensing module comprises, from top to bottom, a dustproof coating, a Si3N4 nanostructure layer, an Au reflection modulation layer, and a single-crystal silicon substrate layer, which are used to sense lunar dust adhesion and generate changes in optical signals. The temperature control and data analysis module includes a temperature control unit, a data processing and analysis unit, and a housing. The temperature control unit is installed in the middle of the bottom surface of the monocrystalline silicon substrate. The edge area of ​​the bottom surface of the monocrystalline silicon substrate is connected to the housing, and a sealing structure is provided at the connection. The data processing and analysis unit is installed inside the housing and has a built-in pre-calibration model for retrieving lunar dust parameters based on the changes in the optical signal.

[0007] Furthermore, the laser excitation unit uses a semiconductor laser with an output laser wavelength of 800~900nm, a linewidth ≤0.05nm, and an output power of 15~30mW. After collimation, the laser forms a parallel spot with a diameter of 1~2mm.

[0008] Furthermore, the signal detection unit integrates a spectrometer and a CMOS camera. The spectrometer has a detection range of 800~900nm, a wavelength resolution of ≤0.1nm, and a sampling interval of 0.5~1s. The CMOS camera has ≥10 million pixels and is equipped with a microscope lens to acquire images of the spatial distribution of lunar dust.

[0009] Furthermore, the dustproof coating is a hydrogen-doped diamond-like coating with a hardness ≥ HV2000, the Au reflection control layer has a thickness of 100~150nm, and the single-crystal silicon substrate layer has a thickness of 300~500μm.

[0010] Furthermore, the Si3N4 nanostructure layer is a square grid array, and the unit of the square grid array is composed of two parallel square pillars, the length of the first square pillar is L1, the length of the second square pillar is L2, the width of the first square pillar and the height of the second square pillar are both W, and the distance between the first square pillar and the second square pillar is g.

[0011] Furthermore, the unit spacing of the square grid array is 500~600nm; L1 and L2 satisfy: 330nm≤L2<L1≤440nm; W, H, and g satisfy: 180nm≤W≤200nm; 150nm≤H≤200nm; 70nm≤g≤80nm.

[0012] Furthermore, the temperature control unit is a Peltier, used to control the operating temperature of the top surface of the Si3N4 metasurface sensing module between -40℃ and 60℃.

[0013] Furthermore, the sealing structure is a metal sealing ring vacuum sealing structure with a sealing rating of ≤10. - ³Pa.

[0014] Furthermore, the pre-calibration model is based on a linear regression algorithm, taking the resonance peak offset Δλ as input and outputting the monthly dust concentration and particle size distribution, with a prediction error ≤5%.

[0015] A submicron lunar dust detection method based on a Si3N4 metasurface, using the aforementioned submicron lunar dust detection device based on a Si3N4 metasurface, specifically includes the following steps: S1. Device initialization: Place the detection device in a dust-free environment, adjust the working temperature of the top surface of the Si3N4 metasurface sensing module to a stable state using Peltier, then start the laser excitation unit to output a stable beam, and use the signal detection unit to collect the BIC resonance baseline spectrum when there is no dust. S2, Lunar Dust Detection; The detection device is placed in a lunar dust detection environment. Lunar dust adheres to the top surface of the Si3N4 metasurface sensing module, causing resonance peak shift. The shifted spectrum and image are acquired in real time. S3. Data Processing: The data processing and analysis unit reduces noise in the spectral signal, extracts the resonance peak shift, and substitutes it into the pre-calibration model to invert the concentration and particle size distribution of lunar dust. S4. Output Results: Outputs monthly dust concentration and particle size parameters.

[0016] Compared with existing technologies, the beneficial effects of the submicron lunar dust detection device and method based on Si3N4 metasurface described in this invention are: 1. Synergistic innovation of materials and mechanisms: This invention combines Si3N4 material, which is resistant to extreme environments, with a high Q-value BIC mechanism to amplify the weak signal of submicron lunar dust into a significant optical response, improving the detection sensitivity by an order of magnitude compared with the traditional laser scattering method.

[0017] 2. High integration and miniaturization: Each module and unit of this invention adopts micro-components, with the overall size ≤15cm×10cm×5cm and weight ≤300g, which is suitable for the load limitations of small platforms such as lunar rovers.

[0018] 3. Design for adaptability to all environments: Through the integrated design of dustproof coating, temperature control unit and sealing structure, this invention ensures that the device can work stably for ≥6 months in the extreme environment of the moon.

[0019] 4. Non-contact real-time monitoring capability: This invention does not require sampling and achieves synchronous real-time detection of "concentration-particle size-distribution" with a response time of ≤1s, supporting dynamic risk warning.

[0020] 5. The submicron lunar dust detection device and method described in this invention have the advantages of high sensitivity, resistance to extreme environments, miniaturization, and real-time online monitoring, and can provide key lunar dust risk management data for lunar exploration missions. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of a submicron lunar dust detection device based on a Si3N4 metasurface according to the present invention; Figure 2 This is a schematic diagram of the Si3N4 nanostructure layer and Au reflection modulation layer described in this invention; Figure 3 This is a schematic diagram of the structure of the unit described in this invention; Figure 4 This is a schematic diagram illustrating the principle of resonance peak wavelength shift caused by lunar dust adhesion as described in this invention. Figure 5 This is a flowchart illustrating the operation of a submicron lunar dust detection device based on a Si3N4 metasurface as described in this invention. Figure 6 This is a schematic diagram of the structure of a submicron lunar dust detection device based on a Si3N4 metasurface, as described in this invention, installed on the external detection panel of a lunar exploration device. In the diagram: 1-Laser excitation unit; 2-Signal detection unit; 3-Dustproof coating; 4-Si3N4 nanostructure layer; 5-Au reflection control layer; 6-Single crystal silicon substrate layer; 7-Temperature control unit; 8-Data processing and analysis unit; 9-Housing shell; 10-Sealing structure 41-Square Column One; 42-Square Column Two. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0023] I. Detailed Implementation Method 1, see [link / reference] Figure 1-5 This embodiment describes a submicron lunar dust detection device based on a Si3N4 metasurface, comprising a laser excitation unit 1, a signal detection unit 2, a Si3N4 metasurface sensing module, and a temperature control and data analysis processing module. The laser excitation unit 1 and the signal detection unit 2 are both disposed above the Si3N4 metasurface sensing module, and the temperature control and data analysis processing module is mounted on the bottom surface of the Si3N4 metasurface sensing module. The laser excitation unit 1 is used to excite a light beam, which is incident at a 45° angle onto the center region of the top surface of the Si3N4 metasurface sensing module. The signal detection unit 2 is used to collect the reflected optical signal; The Si3N4 metasurface sensing module comprises, from top to bottom, a dustproof coating 3, a Si3N4 nanostructure layer 4, an Au reflection modulation layer 5, and a single-crystal silicon substrate layer 6, which are used to sense lunar dust adhesion through BIC high Q value resonance and generate changes in optical signals. The temperature control and data analysis module includes a temperature control unit 7, a data processing and analysis unit 8, and a housing 9. The temperature control unit 7 is installed in the middle of the bottom surface of the monocrystalline silicon substrate 6. The edge area of ​​the bottom surface of the monocrystalline silicon substrate 6 is connected to the housing 9, and a sealing structure 10 is provided at the connection. The data processing and analysis unit 8 is installed inside the housing 9 and has a built-in pre-calibration model. It is used to perform wavelet noise reduction and peak fitting on the signal collected by the signal detection unit 2 based on the changes in the optical signal, and to retrieve the lunar dust parameters.

[0024] Preferably, the laser excitation unit 1 adopts a narrow linewidth semiconductor laser, which can output near-infrared wavelengths, with a wavelength of 800~900nm, a linewidth ≤0.05nm, and an adjustable output power of 15~30mW. After collimation, the laser forms a parallel spot with a diameter of 1~2mm and is incident at a 45° angle.

[0025] Preferably, the signal detection unit 2 integrates a high-resolution micro spectrometer and a high-pixel CMOS camera. The spectrometer has a detection range of 800~900nm, a wavelength resolution of ≤0.1nm, and a sampling interval of 0.5~1s. The CMOS camera has ≥10 million pixels and is equipped with a microscope lens to acquire images of the spatial distribution of lunar dust.

[0026] Preferably, the dustproof coating 3 is a hydrogen-doped diamond-like carbon (aC:H DLC) coating covering the metasurface, with a hardness ≥ HV2000, reducing non-specific adsorption and wear; the Au reflection control layer 5 has a thickness of 100~150nm and a near-infrared reflectivity ≥95%; and the single-crystal silicon substrate layer 6 has a thickness of 300~500μm.

[0027] See attached document Figure 2 and 3 The Si3N4 nanostructure layer 4 is a square grid array. The unit of the square grid array is composed of two parallel square pillars 41 and 42. The length of the square pillar 41 is L1 and the length of the square pillar 42 is L2. The width of the square pillar 41 and the height of the square pillar 42 are both W and H. The distance between the square pillar 41 and the square pillar 42 is g.

[0028] Preferably, the unit spacing of the square grid array is 500~600nm, and the total array size is 8mm×8mm; L1 and L2 satisfy: 330nm≤L2<L1≤440nm, and the lengths of the two square pillars are different to break the symmetry and form a BIC; W, H, and g satisfy: 180nm≤W≤200nm; 150nm≤H≤200nm; 70nm≤g≤80nm.

[0029] Preferably, the temperature control unit 7 is a Peltier, i.e., a semiconductor cooling / heating component, used to control the operating temperature of the top surface of the Si3N4 metasurface sensing module within a stable range of -40℃ to 60℃.

[0030] Preferably, the sealing structure 10 is a metal sealing ring vacuum sealing structure with a sealing level ≤10. - ³Pa protects internal electronic components from the effects of vacuum and radiation.

[0031] The pre-calibration model is based on a linear regression algorithm, taking the resonance peak offset Δλ as input and outputting the monthly dust concentration and particle size distribution, with a prediction error ≤5%.

[0032] Metasurface fabrication and calibration: A Si3N4 thin film was deposited on a silicon substrate using PECVD, followed by electron beam lithography and ICP etching to form a square grid array, with the structural perpendicularity controlled to ≥89°. Its BIC resonance characteristics were calibrated in a simulated lunar environment on Earth, ensuring a resonance wavelength of 850nm±2nm, a Q value ≥10³, and a minimum reflectivity of ≤5%.

[0033] Optical path adjustment: Adjust the laser spot to cover more than 90% of the effective area of ​​the metasurface, optimize the position of the spectrometer probe and the parameters of the CMOS camera, ensure that the signal acquisition efficiency is ≥80%, and be able to distinguish particles with a diameter ≥200nm.

[0034] Pre-calibration model establishment: The existing linear regression algorithm is used as the basic framework. The core innovation lies in the calibration of multiple sets of lunar dust samples (concentration 10~1000 particles / cm², particle size 200~800nm) under simulated lunar environment to establish a special mapping relationship of "resonance peak offset (Δλ) - lunar dust concentration / particle size". This mapping relationship is a customized design adapted to this device, and the model prediction error is ≤5%.

[0035] See attached document Figure 6 The submicron lunar dust detection device based on a Si3N4 metasurface described in this invention can be applied to existing lunar exploration equipment (such as lunar rovers and probes). Installed on the external detection panel of the lunar exploration equipment, it directly contacts the lunar surface environment and serves as a core sensitive component. If the detection concentration exceeds a threshold (e.g., 800 particles / cm²), an alarm is triggered. The metasurface is cleaned periodically, such as by activating a low-power (5mW) laser for self-cleaning every 24 hours to maintain detection performance. Specific steps are as follows: T1. Turn off the "working laser" of the laser excitation unit and switch to the "low-power cleaning laser" (wavelength is the same as the working laser, 800~900nm, power is reduced to 10%~15% of the working power); T2. Fine-tuning the tilt angle of the detection panel of the lunar exploration equipment (using the microgravity environment to reduce the secondary adhesion of lunar dust after cleaning); T3. Clean laser scanning covers the metasurface at a speed of 2 mm / s, with each area scanned twice—utilizing the light pressure effect under lunar vacuum to peel off lunar dust adhering to the metasurface. T4. Resume the working laser, collect the current BIC resonance spectrum, and compare it with the initial baseline spectrum; if the resonance peak shift is ≤ ±0.2nm, the cleaning is deemed qualified; if not qualified, repeat the cleaning process.

[0036] A submicron lunar dust detection method based on a Si3N4 metasurface, using the aforementioned submicron lunar dust detection device based on a Si3N4 metasurface, specifically includes the following steps: S1. Device initialization: Place the detection device in a dust-free environment and adjust the temperature of the top surface of the Si3N4 metasurface sensing module to a stable operating temperature using the temperature control unit 7. Then, start the laser excitation unit 1 to output a stable beam and use the signal detection unit 2 to collect the BIC resonance baseline spectrum (λ0=850nm) when there is no dust. Initialize the metasurface to a stable operating temperature using the temperature control unit 7 so that it can stably generate BIC resonance and obtain a resonance peak with a high Q value.

[0037] S2. Lunar dust detection: The detection device is placed in a lunar dust detection environment. Lunar dust adheres to the top surface of the Si3N4 metasurface sensing module, causing a shift in the BIC resonance peak (Δλ) and a change in reflectivity (ΔR). The detection unit collects spectral and image data at set intervals. S3. Data Processing: The data processing and analysis unit 8 denoises the spectral signal, extracts the resonance peak shift Δλ, and substitutes it into the pre-calibration model to invert the lunar dust concentration and particle size distribution. S4. Output Results: Outputs monthly dust concentration and particle size parameters.

[0038] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A submicron lunar dust detection device based on a Si3N4 metasurface, characterized in that, It includes a laser excitation unit (1), a signal detection unit (2), a Si3N4 metasurface sensing module, and a temperature control and data analysis and processing module. The laser excitation unit (1) and the signal detection unit (2) are both located above the Si3N4 metasurface sensing module, and the temperature control and data analysis and processing module is installed on the bottom surface of the Si3N4 metasurface sensing module. The laser excitation unit (1) is used to excite a light beam, which is incident at a 45° angle onto the center region of the top surface of the Si3N4 metasurface sensing module. The signal detection unit (2) is used to collect the reflected optical signal; The Si3N4 metasurface sensing module comprises a dustproof coating (3), a Si3N4 nanostructure layer (4), an Au reflection modulation layer (5), and a single-crystal silicon substrate layer (6) stacked from top to bottom, for sensing lunar dust adhesion and generating changes in optical signals; The temperature control and data analysis module includes a temperature control unit (7), a data processing and analysis unit (8), and a housing (9). The temperature control unit (7) is installed in the middle of the bottom surface of the monocrystalline silicon substrate (6). The edge area of ​​the bottom surface of the monocrystalline silicon substrate (6) is connected to the housing (9), and a sealing structure (10) is provided at the connection. The data processing and analysis unit (8) is installed inside the housing (9) and has a built-in pre-calibration model for inverting lunar dust parameters based on the changes in the optical signal.

2. The submicron lunar dust detection device based on a Si3N4 metasurface according to claim 1, characterized in that, The laser excitation unit (1) uses a semiconductor laser with an output laser wavelength of 800~900nm, a linewidth of ≤0.05nm, and an output power of 15~30mW. After collimation, the laser forms a parallel spot with a diameter of 1~2mm.

3. The submicron lunar dust detection device based on a Si3N4 metasurface according to claim 1, characterized in that, The signal detection unit (2) integrates a spectrometer and a CMOS camera. The spectrometer has a detection range of 800~900nm, a wavelength resolution of ≤0.1nm, and a sampling interval of 0.5~1s. The CMOS camera has ≥10 million pixels and is equipped with a microscope lens to acquire images of the spatial distribution of lunar dust.

4. The submicron lunar dust detection device based on a Si3N4 metasurface according to claim 1, characterized in that, The dustproof coating (3) is a hydrogen-doped diamond-like coating with a hardness ≥ HV2000. The Au reflection control layer (5) has a thickness of 100~150nm, and the single crystal silicon substrate layer (6) has a thickness of 300~500μm.

5. The submicron lunar dust detection device based on a Si3N4 metasurface according to claim 1, characterized in that, The Si3N4 nanostructure layer (4) is a square grid array. The unit of the square grid array is composed of two parallel square pillars (41) and two square pillars (42). The length of the square pillar (41) is L1 and the length of the square pillar (42) is L2. The width of the square pillar (41) and the height of the square pillar (42) are both W and H. The distance between the square pillar (41) and the square pillar (42) is g.

6. The submicron lunar dust detection device based on a Si3N4 metasurface according to claim 5, characterized in that, The unit spacing of the square grid array is 500~600nm; L1 and L2 satisfy: 330nm≤L2<L1≤440nm; W, H, and g satisfy: 180nm≤W≤200nm; 150nm≤H≤200nm; 70nm≤g≤80nm.

7. The submicron lunar dust detection device based on a Si3N4 metasurface according to claim 1, characterized in that, The temperature control unit (7) is a Peltier.

8. The submicron lunar dust detection device based on a Si3N4 metasurface according to claim 1, characterized in that, The sealing structure (10) is a metal sealing ring vacuum sealing structure with a sealing level ≤10. - ³Pa.

9. The submicron lunar dust detection device based on a Si3N4 metasurface according to claim 1, characterized in that, The pre-calibration model is based on a linear regression algorithm, taking the resonance peak offset Δλ as input and outputting the monthly dust concentration and particle size distribution, with a prediction error ≤5%.

10. A submicron lunar dust detection method based on a Si3N4 metasurface, characterized in that, The submicron lunar dust detection device based on a Si3N4 metasurface as described in any one of claims 1-9 specifically includes the following steps: S1. Device initialization: Place the detection device in a dust-free environment and adjust the working temperature of the top surface of the Si3N4 metasurface sensing module to a stable temperature using the temperature control unit (7). Then, start the laser excitation unit (1) to output a stable beam and use the signal detection unit (2) to collect the BIC resonance baseline spectrum when there is no dust. S2, Lunar Dust Detection; The detection device is placed in a lunar dust detection environment. Lunar dust adheres to the top surface of the Si3N4 metasurface sensing module, causing resonance peak shift. The shifted spectrum and image are acquired in real time. S3, Data Processing: The data processing and analysis unit (8) reduces noise in the spectral signal, extracts the resonance peak shift, and substitutes it into the pre-calibration model to invert the concentration and particle size distribution of lunar dust. S4. Output Results: Outputs monthly dust concentration and particle size parameters.

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