Visible near-infrared low transmission analog vegetation, mid-infrared and microwave high transmission all-dielectric film system structure
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV
- Filing Date
- 2026-04-16
- Publication Date
- 2026-07-10
Smart Images
Figure CN122063719B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hyperspectral camouflage technology, specifically relating to a full-dielectric film structure that simulates vegetation with low transmission in the visible and near-infrared range and high transmission in the mid-infrared and microwave ranges. Background Technology
[0002] With the rapid development of modern detection technology, single-band stealth is no longer sufficient to meet practical needs. In addition to common infrared and microwave detection methods, hyperspectral imaging technology, with its spectral resolution of 5-10 nm, poses a significant challenge to camouflage techniques.
[0003] As the most widely used background for ground targets, green vegetation has multiple spectral characteristics that make it easily detectable by hyperspectral imaging, thereby revealing camouflaged targets. Hyperspectral simulations of green vegetation generally reveal the following key reflectance spectral features: (1) a green peak at 550 nm; (2) a red edge at 680-780 nm; (3) a near-infrared plateau at 800-1300 nm; and (4) water absorption peaks at 1450 nm and 1950 nm. Therefore, the demand for hyperspectral simulation technology of vegetation in the visible and near-infrared bands is increasingly urgent.
[0004] Currently, there is some research on visible and near-infrared hyperspectral camouflage film systems. Existing film systems, such as a visible-laser-infrared compatible camouflage film mimicking natural vegetation (patent CN119717096A), a thermal infrared low-emissivity green leaf-mimicking multilayer film and its preparation method (patent CN119758501A), and a multilayer film for hyperspectral-laser stealth (patent CN114690278A), can simulate the spectral characteristics of vegetation, but they have significant shortcomings: the above film systems only simulate the reflectivity of vegetation, exhibiting high transmittance in the 1500–2500 nm band, which does not match the low transmittance of real vegetation in this band. For example, the CN119717096A film system has an average transmittance of 83.4% in this band. Since the above film systems do not simulate the low transmittance of vegetation in the 1500–2500 nm band, if applied to high-reflectivity substrates such as metal armor, the simulated vegetation spectrum will be destroyed.
[0005] To avoid compromising its communication and detection functions, the designed membrane system must also possess excellent mid-infrared and microwave transmission properties. Therefore, developing a novel membrane structure that can simulate vegetation in the visible and near-infrared range while simultaneously ensuring high mid-infrared and microwave transmission has significant theoretical research value and practical application prospects. Summary of the Invention
[0006] To address the problems existing in the prior art, the present invention provides an all-dielectric membrane structure with low transmission in the visible and near-infrared regions to simulate vegetation and high transmission in the mid-infrared and microwave regions.
[0007] The all-dielectric membrane structure of the present invention comprises, from top to bottom, a visible and near-infrared simulated vegetation layer, a mid-infrared high-transmittance layer, and a substrate layer.
[0008] The visible and near-infrared simulated vegetation and mid-infrared high-transmittance layer are formed by alternating stacking of a first dielectric layer, a second dielectric layer, a third dielectric layer and a fourth dielectric layer, with the fourth dielectric layer being the film layer closest to the substrate.
[0009] Wherein, the first dielectric layer is selected from a material with a refractive index of 2 to 3; the second dielectric layer is selected from a material with a refractive index of 1 to 2; the third dielectric layer is selected from a material with a refractive index of 3 to 5; and the fourth dielectric layer is selected from a material with a refractive index of 3 to 5 and high loss characteristics in the visible and near-infrared ranges.
[0010] The all-dielectric film structure exhibits characteristics of simulated vegetation reflectance spectrum in the 380-2500nm visible and near-infrared band, and has low transmittance in this band; it has high transmittance in the 3-5µm and 8-14µm mid-infrared atmospheric window bands; and it has high transmittance in the microwave band.
[0011] Furthermore, the first dielectric layer is ZnS or HfO2; the second dielectric layer is YbF3; the third dielectric layer is Ge or Si; and the fourth dielectric layer is amorphous InSb or crystalline Ge2Sb2Se4Te1.
[0012] Furthermore, the first dielectric layer is ZnS; the second dielectric layer is YbF3; the third dielectric layer is Ge; and the fourth dielectric layer is amorphous InSb.
[0013] Furthermore, the thickness of the first dielectric layer is 10~150nm; the thickness of the second dielectric layer is 30~100nm; the thickness of the third dielectric layer is 4~600nm; and the thickness of the fourth dielectric layer is 500~1000nm.
[0014] Furthermore, in top-down order, the thickness of the first first dielectric layer is 5~15nm; the thickness of the second, third, and fourth first dielectric layers is 50~150nm; the thickness of the first and third second dielectric layers is 20~50nm; the thickness of the remaining second dielectric layers is 50~100nm; the thickness of the first and fourth third dielectric layers is 4~10nm; and the thickness of the second and third third dielectric layers is 40~600nm.
[0015] Furthermore, the structure of the visible and near-infrared simulated vegetation and the mid-infrared high-transmittance layer from top to bottom is as follows:
[0016] A ZnS layer with a thickness of 10 nm, a YbF3 layer with a thickness of 44 nm, a Ge layer with a thickness of 4 nm, a ZnS layer with a thickness of 75 nm, a YbF3 layer with a thickness of 87 nm, a ZnS layer with a thickness of 52 nm, a Ge layer with a thickness of 532 nm, a ZnS layer with a thickness of 125 nm, a Ge layer with a thickness of 48 nm, a YbF3 layer with a thickness of 36 nm, an InSb layer with a thickness of 995 nm, a Ge layer with a thickness of 7 nm, and an InSb layer with a thickness of 990 nm.
[0017] Furthermore, the average transmittance of the all-dielectric film structure in the 1500-2500nm wavelength band is less than 0.03.
[0018] Furthermore, the all-dielectric film structure has a reflectance of over 92% in the 380-2500nm wavelength band, which meets the spectral requirements of the green vegetation reference standard.
[0019] Furthermore, the transmittance of the all-dielectric film structure in the mid-infrared atmospheric window bands of 3-5µm and 8-14µm is higher than 0.65.
[0020] Furthermore, the total thickness of the all-dielectric film structure is less than 3µm.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] 1. Achieved vegetation simulation in the visible and near-infrared under low transmittance conditions: The all-dielectric film structure proposed in this invention not only achieves hyperspectral simulation of vegetation reflectance in the visible and near-infrared, but also reduces the average transmittance of 1500-2500 nm to 0.025 by introducing amorphous InSb, a high-loss material in the visible and near-infrared, thereby achieving simulation of low transmittance of vegetation in this band. This solves the problem that previous high-transmittance vegetation simulation film systems could not be applied to high-reflectance substrates such as metal armor.
[0023] 2. High transmittance of mid-infrared atmospheric window achieved: In the atmospheric window bands of 3-5 µm and 8-14 µm, the infrared transmittance (transmitted into the substrate) is as high as 0.6730 and 0.6729, respectively, which can be used as infrared windows.
[0024] 3. Excellent hyperspectral simulation performance: The all-dielectric film structure of this invention exhibits excellent performance in visible and near-infrared vegetation simulation, with a reflectance of over 92% meeting the spectral channel requirements of the green vegetation reference standard.
[0025] 4. High design feasibility: The all-dielectric membrane system structure of this invention uses mature thin film materials, has a relatively simple structure, and the number of layers is within an acceptable range, which makes large-scale preparation possible. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the membrane structure in an embodiment of the present invention;
[0027] In the diagram, 1 – first dielectric layer; 2 – second dielectric layer; 3 – third dielectric layer; 4 – fourth dielectric layer; 5 – substrate layer;
[0028] Figure 2 This is a physical diagram of the membrane structure in an embodiment of the present invention;
[0029] Figure 3 The visible and near-infrared reflectance and transmission spectra of the membrane structure in this embodiment of the invention are shown.
[0030] Figure 4 This is the mid-infrared transmission spectrum of the membrane structure in an embodiment of the present invention;
[0031] Figure 5 This is a microwave transmission spectrum of the membrane structure in an embodiment of the present invention. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0033] This application, by introducing amorphous InSb material, not only enables hyperspectral simulation of vegetation in the 380-2500 nm range, but also simulates low-transmittance vegetation in the 1500-2500 nm band, where previous thin-film systems had high transmittance. This allows the designed film system to be applied to high-reflectivity substrates such as metal armor, while also exhibiting high transmittance in the mid-infrared and microwave bands for communication purposes. Specifically:
[0034] The all-dielectric membrane structure of this application comprises, from top to bottom, visible and near-infrared simulated vegetation, a mid-infrared high-transmittance layer, and a substrate layer; the visible and near-infrared simulated vegetation and the mid-infrared high-transmittance layer are formed by alternating stacking of first, second, third, and fourth dielectric layers in a predetermined order and thickness, with the fourth dielectric layer being the membrane layer closest to the substrate layer.
[0035] The visible and near-infrared simulated vegetation and the mid-infrared high-transmittance layer are composed of multiple layers of dielectric materials with specific optical properties. The main function of this layer is to regulate the reflectivity of the structure, achieving a high degree of similarity to the reflectivity spectrum of vegetation. Simultaneously, due to the loss of the amorphous InSb in the fourth dielectric layer in this band, the membrane system exhibits low transmittance in the visible and near-infrared band. In the mid-infrared band, due to the low material loss, the membrane system can be designed to achieve high transmittance. The dielectric layer materials used in the above-mentioned all-dielectric membrane structure are all low-conductivity dielectric materials, and the overall thickness of all dielectric film layers is negligible compared to the microwave wavelength, ensuring high microwave transmittance of the membrane structure.
[0036] Preferably, the first dielectric layer is selected from a material with a refractive index of 2 to 3;
[0037] The second dielectric layer is selected from a material with a refractive index of 1 to 2;
[0038] The third dielectric layer is selected from a material with a refractive index of 3 to 5;
[0039] The fourth dielectric layer is selected from visible and near-infrared high-loss and mid-infrared low-loss materials with a refractive index of 3 to 5.
[0040] As a further preferred option, the first dielectric layer is ZnS or HfO2;
[0041] The second dielectric layer is YbF3;
[0042] The third dielectric layer is Ge or Si;
[0043] The fourth dielectric layer is either InSb (amorphous) or Ge2Sb2Se4Te1 (crystalline).
[0044] As a further preferred option, the first dielectric layer is ZnS;
[0045] The second dielectric layer is YbF3;
[0046] The third dielectric layer is Ge;
[0047] The fourth dielectric layer is InSb (amorphous).
[0048] Preferably, the thickness of the first dielectric layer is 10~150 nm;
[0049] The thickness of the second dielectric layer is 30~100nm;
[0050] The thickness of the third dielectric layer is 4~600nm;
[0051] The thickness of the fourth dielectric layer is 500~1000nm.
[0052] As a further preferred embodiment, in the order from top to bottom, the thickness of the first first dielectric layer is 5-15 nm; the thickness of the second, third, and fourth first dielectric layers is 50-150 nm; the thickness of the first and third second dielectric layers is 20-50 nm; the thickness of the remaining second dielectric layers is 50-100 nm; the thickness of the first and fourth third dielectric layers is 4-10 nm; the thickness of the second and third third dielectric layers is 40-600 nm; and the thickness of the fourth dielectric layer is 500-1000 nm.
[0053] As a specific preferred embodiment, the all-dielectric film structure with low transmission in the visible and near-infrared to simulate vegetation and high transmission in the mid-infrared and microwave is ZnS (10 nm) / YbF3 (44 nm) / Ge (4 nm) / ZnS (75 nm) / YbF3 (87 nm) / ZnS (52 nm) / Ge (532 nm) / ZnS (125 nm) / Ge (48 nm) / YbF3 (36 nm) / InSb (995 nm) / Ge (7 nm) / InSb (990 nm) / Si.
[0054] For the visible and near-infrared simulated vegetation layer: This application utilizes a combination of multilayer media and achieves simulation of the characteristic reflectance spectrum of vegetation in the 380-2500 nm band through thin film interference and refractive index gradient matching. Due to the high loss characteristics of amorphous InSb, this layer has extremely low transmittance in the visible and near-infrared band.
[0055] Regarding the high-transmittance portion of the infrared atmospheric window in the embodiments: This application employs a full-dielectric film structure constructed from lossless or low-loss infrared transparent materials. By optimizing the thickness and materials of each layer, the incident light in the mid-infrared region has a high transmittance, preserving the information transmission capability of the mid-infrared region of the film system, and can be used as an infrared window.
[0056] The all-dielectric film structure of this application, which simulates vegetation with low transmission in the visible and near-infrared bands and high transmission in the mid-infrared and microwave bands, can simulate vegetation spectra in the visible to near-infrared bands, achieve high transmission in the infrared atmospheric window band, and simultaneously possess high microwave transmittance. It is particularly suitable for equipment with hyperspectral camouflage, mid-infrared and microwave communication requirements.
[0057] Example:
[0058] like Figure 1 As shown, in one embodiment, a fully dielectric film structure with low transmission of visible and near-infrared simulated vegetation and high transmission of mid-infrared and microwave is, from top to bottom, consisting of: visible and near-infrared simulated vegetation and mid-infrared high-transmittance layer, and substrate layer 5.
[0059] The near-infrared simulated vegetation and mid-infrared high-transmittance layer, from top to bottom, comprises a first dielectric layer 1, a second dielectric layer 2, a third dielectric layer 3, and a fourth dielectric layer 4. The materials of the first, second, third, and fourth dielectric layers are preferably ZnS, YbF3, Ge, and InSb, respectively. The specific thicknesses of the structure are: ZnS (10 nm) / YbF3 (44 nm) / Ge (4 nm) / ZnS (75 nm) / YbF3 (87 nm) / ZnS (52 nm) / Ge (532 nm) / ZnS (125 nm) / Ge (48 nm) / YbF3 (36 nm) / InSb (995 nm) / Ge (7 nm) / InSb (990 nm). The total thickness of this structure is 2.958 µm. Since the total thickness is negligible compared to the microwave wavelength and the materials are all low-conductivity dielectrics, it exhibits high transmittance in the microwave band.
[0060] Images of the fabricated all-dielectric membrane systems with low transmittance in the visible and near-infrared regions simulating vegetation, and high transmittance in the mid-infrared and microwave regions are shown below. Figure 2 As shown.
[0061] Performance testing:
[0062] Experimental data for visible and near-infrared reflectance spectra were obtained by measuring reflectance R using a UV-Vis-NIR spectrophotometer.
[0063] The visible and near-infrared reflectance spectra of the all-dielectric film structure prepared above, as determined by simulation and experiments, are shown below. Figure 3 As shown. By Figure 3 It can be seen that the experimental and simulation results of this membrane structure are in high agreement across the entire 380-2500 nm visible and near-infrared band. The slight shift in the experimentally measured reflectance spectrum is mainly attributed to errors in the membrane fabrication process. Specifically, the spectrum of the prepared all-dielectric membrane structure is highly similar to the reflectance spectrum of standard vegetation. Simulation calculations show that over 92% of the reflectance meets the reference standard spectral channel for green vegetation, demonstrating good simulation effects for key characteristics of vegetation in the visible and near-infrared bands, such as the green peak, red edge, near-infrared plateau, and multiple water absorption peaks. Because the selected amorphous InSb has strong absorption in the visible and near-infrared bands, the all-dielectric membrane structure exhibits low transmittance across the entire 380-2500 nm band.
[0064] Transmittance T was measured using a Fourier transform infrared spectrometer (FTIR) for mid-infrared radiation spectroscopy.
[0065] The infrared transmission spectrum of the all-dielectric film system obtained above is shown in the figure. Figure 4As shown, thanks to the low loss of each layer of the all-dielectric film structure in the mid-infrared band, the infrared transmittance (incident in the substrate) is as high as 0.6730 and 0.6729 in the atmospheric window bands of 3-5 µm and 8-14 µm, respectively.
[0066] The microwave transmittance of the all-dielectric film structure prepared above is as follows: Figure 5 As shown, within the 5-40GHz range, the device exhibits almost no attenuation of microwave signals, and its transmittance remains consistently above 99.9%, demonstrating excellent microwave transmission capability.
[0067] In this embodiment, by optimizing the thickness combination of ZnS, YbF3, Ge, and InSb layers, the overall film structure not only achieves vegetation simulation in the visible and near-infrared range but also maintains high transmittance in the mid-infrared and microwave bands. This synergistic effect of the multilayer nanofilm structure enables the film to achieve excellent visible and near-infrared vegetation simulation performance, making it suitable for scenarios requiring low visible and near-infrared detectability against a vegetated background, while also being compatible with mid-infrared and microwave communication, such as its use as an infrared window for vehicles or buildings.
[0068] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. The present invention is not limited to the examples described above. Any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.
Claims
1. A fully dielectric membrane structure with low visible and near-infrared transmission simulating vegetation and high mid-infrared and microwave transmission, characterized in that, From top to bottom, it consists of visible and near-infrared simulated vegetation, a mid-infrared high-transmittance layer, and a substrate layer; The visible and near-infrared simulated vegetation and mid-infrared high-transmittance layer are composed of a first dielectric layer, a second dielectric layer, a third dielectric layer and a fourth dielectric layer, with the fourth dielectric layer being the film layer closest to the substrate. The all-dielectric film structure exhibits characteristics of simulated vegetation reflectance spectrum in the 380-2500nm visible and near-infrared band, and has low transmittance in this band; the transmittance in the 3-5µm and 8-14µm mid-infrared atmospheric window bands is higher than 0.65; and it has high transmittance in the microwave band. The first dielectric layer is ZnS; the second dielectric layer is YbF3; the third dielectric layer is Ge; and the fourth dielectric layer is amorphous InSb. The structure of the visible and near-infrared simulated vegetation and the mid-infrared high-transparency layer from top to bottom is as follows: A ZnS layer with a thickness of 10 nm, a YbF3 layer with a thickness of 44 nm, a Ge layer with a thickness of 4 nm, a ZnS layer with a thickness of 75 nm, a YbF3 layer with a thickness of 87 nm, a ZnS layer with a thickness of 52 nm, a Ge layer with a thickness of 532 nm, a ZnS layer with a thickness of 125 nm, a Ge layer with a thickness of 48 nm, a YbF3 layer with a thickness of 36 nm, an InSb layer with a thickness of 995 nm, a Ge layer with a thickness of 7 nm, and an InSb layer with a thickness of 990 nm.
2. The all-dielectric film system structure according to claim 1, characterized in that, The average transmittance of the all-dielectric film structure in the 1500-2500nm wavelength band is less than 0.03.