Silver-series high-reflective film and preparation method thereof

Abstract

The invention relates to the technical field of nano film preparation, and discloses a silver-based high-reflection film and a preparation method thereof.The silver-based high-reflection film comprises a substrate, a substrate layer, a high-reflection layer and a reflection increasing layer, the substrate is made of aluminum alloy, the substrate layer is located on the substrate and comprises a first SiO2 layer and a first Al2O3 layer, the first Al2O3 layer is tightly attached to the high-reflection layer, and the high-reflection layer is located on the substrate and comprises a second SiO2 layer and a second Al2O3 layer. The high-reflection layer is located between the substrate layer and the reflection-increasing layer, the high-reflection layer is a silver film, the reflection-increasing layer comprises a dielectric film system with alternate high and low refractive indexes and a second SiO2 layer which is located on the outermost layer and plays a role in preventing moisture and corrosion, and the dielectric film system with alternate high and low refractive indexes comprises a second Al2O3 layer and a first TiO2 layer from bottom to top. By utilizing the scheme of the invention, the reflectivity of the designed silver-series film can be as high as possible, and the silver-series high-reflectivity film which meets conditions and can save manpower and material resources is obtained.

Description

Technical Field

[0001] This invention relates to the field of nanofilm preparation technology, specifically to a silver-based high-reflectivity film and its preparation method. Background Technology

[0002] In the context of rapid technological development in the new era, optoelectronic turrets are increasingly used in the military field. More advanced turrets mean greater area-of-effect strike capabilities. The mirror material is primarily aluminum alloy, currently using 6061 aluminum alloy. Single-point diamond machining results in relatively large grains, leading to poor optical performance. Metal films such as pure aluminum or nickel can be deposited on the aluminum alloy substrate, followed by polishing. However, aluminum alloy mirrors do not perform well in the visible light band, typically only meeting infrared requirements. Among all metals, silver has the highest reflectivity from 400nm to the infrared range, with lower emissivity and low polarization characteristics in the infrared range. The disadvantage of silver films is that reflectivity drops sharply below 400nm, reaching its lowest point at 320nm due to surface plasmon resonance (SPR). Furthermore, its reactive chemical properties make unprotected silver films susceptible to corrosion and discoloration in industrial environments. Besides damaging optical performance, this also compromises electrical properties. Discoloration increases the surface resistivity of silver plating by approximately 20%-80%, leading to energy loss and decreased reliability and stability of electronic equipment, posing serious safety hazards. Unprotected silver exposed to air and sunlight almost immediately loses its luster. Furthermore, since photon absorption in silver occurs at 4 eV (310 nm), another form of corrosion in Ag films is photocorrosion, which primarily occurs outdoors. There are indications that the presence of sulfur in ambient air exacerbates the photocorrosion process. In summary, sulfur resistance has become an important research focus for silver-based films, and the development of high-bandwidth, high-reflectivity silver-based films with long-term environmental durability is of great significance for the development of various optical instruments used in harsh environments.

[0003] The design parameters of silver are crucial for ensuring high reflectivity and enhancing reflectivity, as they significantly impact surface morphology, roughness, grain size, and crystal orientation. Current research findings indicate shortcomings in the study of silver's design parameters, specifically as follows: (1) Some researchers assumed that if the reflectivity data of a single-layer silver film is good, then an anti-reflective silver film with an added dielectric protective layer should also be good, but no research was conducted.

[0004] (2) The study on the evaporation rate of silver film is not comprehensive and the rate range is relatively limited, especially for film systems with charged dielectric films. Summary of the Invention

[0005] This invention provides a silver-based high-reflectivity film and its preparation method. By fine-tuning the film thickness and refractive index changes, the silver-based film is designed and simulated to maximize its reflectivity, providing a theoretical basis for the experiment.

[0006] Therefore, the present invention provides the following technical solution: A silver-based high-reflectivity film includes a substrate, a substrate layer, a high-reflectivity layer, and an anti-reflection layer. The substrate is made of aluminum alloy. The substrate layer is located on the substrate and includes a first SiO2 layer and a first Al2O3 layer. The first Al2O3 layer is in close contact with the high-reflectivity layer. The high-reflectivity layer is located between the substrate layer and the anti-reflection layer. The high-reflectivity layer is a silver film. The anti-reflection layer includes a dielectric film system with alternating high and low refractive indices and a second SiO2 layer located on the outermost layer for moisture and corrosion protection. The dielectric film system with alternating high and low refractive indices consists of a second Al2O3 layer and a first TiO2 layer from bottom to top.

[0007] Optionally, the thickness of the first SiO2 layer is 15nm, the thickness of the first Al2O3 layer is 30nm, the thickness of the high reflectivity layer is 120nm, the thickness of the second Al2O3 layer is 40nm, the thickness of the first TiO2 layer is 50nm, and the thickness of the second SiO2 layer is 120nm.

[0008] A method for preparing a silver-based high-reflectivity film, the method comprising: Step 1: Select the film material and determine the structure of the silver-based high-reflectivity film; Step 2: Set the environmental parameters; Step 3: Perform design and optimization simulation of the silver-based high-reflectivity film; Step 4: Perform a simulation to fine-tune the thickness of the silver-based high-reflectivity film; Step 5: Prepare the silver-based high-reflectivity film.

[0009] Optionally, in step 1, when selecting the film material, Al2O3 is selected as the close-fitting layer of the silver film, and SiO2 is selected as the outermost layer with a thickness of more than 100nm to play a role in preventing moisture and corrosion. Al2O3 is selected as the low-refractive layer and TiO2 is selected as the high-refractive layer. The silver-based high-reflectivity film is determined to include a substrate, a substrate layer, a high-reflectivity layer and an anti-reflection layer. The substrate is made of aluminum alloy. The substrate layer is located on the substrate and includes a first SiO2 layer and a first Al2O3 layer. The first Al2O3 layer is close to the high-reflectivity layer. The high-reflectivity layer is located between the substrate layer and the anti-reflection layer. The high-reflectivity layer is a silver film. The anti-reflection layer includes a dielectric film system with alternating high and low refractive indices and a second SiO2 layer located on the outermost layer to play a role in preventing moisture and corrosion. The dielectric film system with alternating high and low refractive indices consists of a second Al2O3 layer and a first TiO2 layer from bottom to top.

[0010] Optionally, in step 2, when setting environmental parameters, it is necessary to set the incident and ingress media of the membrane system, the substrate material and its thickness, the light source and its center wavelength and incident angle, and the wavelength and incident angle range.

[0011] Optionally, in step 3, a silver film thickness simulation analysis is performed. First, silver is added separately as the front surface film layer, with a thickness of 40-120nm. The design simulation is performed every 20nm as a design unit to obtain reflectivity data. The simulation shows that the reflectivity of the silver film increases with the increase of the thickness above 425nm. The reflectivity is basically the same when the silver film thickness is above 80nm, but there are still slight differences. Therefore, the silver film thickness is selected to be above 100nm to ensure good optical performance of the silver film.

[0012] Optionally, in step 3, when designing and optimizing the silver-based high-reflectivity film, the substrate layer is selected as 15nm SiO2 / 30nm Al2O3. The initial thickness of the silver film and the second SiO2 layer is set to 120nm. The second Al2O3 layer and the first TiO2 layer are each λ0 / 4 thick, i.e., a quarter wavelength. Simulation shows the reflective layer system to be 120nm Ag / (λ0 / 4)Al2O3 / (λ0 / 4)TiO2 / 120nm SiO2. During simulation, significant absorption is observed in the 400-450nm wavelength band. Based on this, an optimization target is set: reflectivity, with a target value of 99%, optimizing the 400-450nm wavelength band. The second Al2O3 layer and the first TiO2 layer are set as optimizable, and the variable median function method is used for thickness optimization analysis. Then, based on the simulation results, keeping the substrate layer unchanged, the design of the alternating high and low refractive index dielectric film system is changed for optimization and comparison. The 120nm reflective layer system is determined to be optimal. Ag / 37nm Al2O3 / 48nmTiO2 / 120nm SiO2.

[0013] Optionally, in step 4, the second Al2O3 layer and the first TiO2 layer are first optimized. The thickness of the second Al2O3 layer is 35-40 nm, and the thickness of the first TiO2 layer is 45-50 nm. By taking the maximum and minimum values ​​of the two film thicknesses for comprehensive optimization, the simulation results determine that the thickness of the second Al2O3 layer is 40 nm, and the reflectivity is best when the thickness of the first TiO2 layer is 50 nm. Then, based on the thickness of the second Al2O3 layer being 40 nm and the thickness of the first TiO2 layer being 50 nm, the second SiO2 layer is fine-tuned through simulation. The thickness is fine-tuned within the range of 110-130 nm, and the simulation results determine that the thickness of the second SiO2 layer is 120 nm. Finally, simulations are performed for oblique incidence and polarization conditions to determine that the reflective layer film system is 120 nm Ag / 40 nm Al2O3 / 50 nm TiO2 / 120 nm SiO2.

[0014] Optionally, step 5 includes: Step 51: Pre-melt the first SiO2 layer (15nm) and the first Al2O3 layer; set the coating parameters of the silver-based high-reflectivity film and add silver film material; Step 52: Perform vacuuming and turn on the ion source to bombard the substrate; Step 53: Deposit the first SiO2 layer (15 nm) and the first Al2O3 layer (30 nm); Step 54: Install the baffle plate to pre-melt the silver film of the high-reflectivity layer; Step 55: Complete the deposition of the silver film of the high reflectivity layer, with a deposition thickness of 120 nm; Step 56: Turn off the ion source and release the baffle. Step 57: Turn on the ion source and deposit the second Al2O3 layer at 40 nm. After depositing the second Al2O3 layer, deposit the first TiO2 layer at 50 nm. After depositing the first TiO2 layer, deposit the second SiO2 layer at 120 nm.

[0015] Optionally, in step 51, when setting the coating parameters of the silver-based high-reflectivity film, the first SiO2 layer is set to 15nm, the first Al2O3 layer to 30nm, the high-reflectivity layer to 120nm, the second Al2O3 layer to 40nm, the first TiO2 layer to 50nm, and the second SiO2 layer to 120nm.

[0016] This invention relates to a silver-based high-reflectivity film with high reflectivity in the 400-1000nm visible light band and its preparation method, solving problems such as insufficient reflectivity, weak corrosion resistance, and poor film-substrate adhesion in existing technologies. This invention uses Tfcalc software to design various high-reflectivity films for comparison and optimization. Based on this, the dielectric film layer is fine-tuned, demonstrating that potential errors in the dielectric layer during coating do not have a significant impact. A high-reflectivity film system of Sub / 15nm SiO2 / 30nm Al2O3 / 120nm Ag / 40nm Al2O3 / 50nm TiO2 / 120nm SiO2 with a reflectivity of over 95% is obtained. This invention simulates potential changes in the refractive index of the dielectric layer and oblique incidence conditions during coating, proving that even under adverse conditions, this film system can still maintain a reflectivity of over 95%, exhibiting high tolerance and providing a sound theoretical basis for practical coating. The silver-based high-reflectivity film actually prepared through simulation has an average reflectivity of over 50% in the 400-1000nm wavelength range, proving that the method of this invention can obtain a silver-based high-reflectivity film that meets the requirements and saves manpower and resources. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a silver-based high-reflectivity film in a specific embodiment of the present invention; Figure 2 This is a flowchart of a method for preparing a silver-based high-reflectivity film in a specific embodiment of the present invention; Figure 3 This is a schematic diagram showing the comparison of reflectivity before and after optimization in a specific embodiment of the present invention; Figure 4 This is a comparison chart of the reflectivity of the anti-reflective silver film in a specific embodiment of the present invention; Figure 5 This is a schematic diagram showing the comparison of reflectivity after adding a dielectric film pair in a specific embodiment of the present invention; Figure 6 This is a schematic diagram showing the comparison of reflectivity after fine-tuning the thickness of Al2O3 and TiO2 in a specific embodiment of the present invention. Figure 7 This is a schematic diagram showing the comparison of reflectivity after fine-tuning the SiO2 thickness in a specific embodiment of the present invention; Figure 8This is a schematic diagram illustrating the effect of TiO2 refractive index variation on the reflectivity of a high-reflectivity film in a specific embodiment of the present invention; Figure 9 This is a schematic diagram showing the average reflectance at different tilt angles in a specific embodiment of the present invention; Figure 10 15 is a specific embodiment of the present invention. o A schematic diagram of the reflectivity of polarized light; Figure 11 60 is a specific embodiment of the present invention. o A schematic diagram of the reflectivity of polarized light; Figure 12 This is a schematic diagram of reflectivity at wavelengths of 400-1200nm in a specific embodiment of the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] like Figure 1 The diagram shown is a schematic representation of the structure of the silver-based high-reflectivity film of the present invention. The silver-based high-reflectivity film of the present invention includes a substrate, a substrate layer, a high-reflectivity layer, and an anti-reflection layer. The substrate is made of aluminum alloy; the substrate layer consists of 15nm SiO2 and 30nm Al2O3 from bottom to top; the high-reflectivity layer is made of 120nm Ag; and the anti-reflection layer consists of 40nm Al2O3, 50nm TiO2, and 120nm SiO2 from bottom to top.

[0022] Based on the principles of thin-film optics and the current research status of silver-based high-reflectivity films both domestically and internationally, Tfcalc software was used to design various film systems with different materials. The film thickness and refractive index were fine-tuned to design and simulate silver-based films, aiming to maximize the reflectivity of the designed films and provide a theoretical basis for experiments. Figure 2 The diagram shown is a flowchart of a method for preparing a silver-based high-reflectivity film according to an embodiment of the present invention, including the following steps: Step 101: Select the membrane material.

[0023] When designing broadband high-reflectivity films, metallic materials such as aluminum, gold, and silver are generally selected. Silver has the highest reflectivity from 400nm to the infrared range, with even lower emissivity and low polarization characteristics in the infrared range. Therefore, in designing high-reflectivity films, silver-based high-reflectivity films can achieve higher reflectivity in both the visible and infrared bands. Given the good adhesion between silver and Al2O3 and the waterproof properties of SiO2, Al2O3 is chosen as the bonding layer for the silver film. SiO2 serves as the outermost layer with a thickness of over 100nm to provide moisture and corrosion protection. To increase reflectivity, a dielectric film system with alternating high and low refractive indices is needed as an anti-reflection layer. Considering that the refractive indices of Al2O3 and SiO2 are 1.62 and 1.455 respectively (considered low refractive indices), TiO2, a material with good chemical stability, is selected as the high refractive index layer. The anti-reflection effect is achieved through the alternating Al2O3 / TiO2 layers with high and low refractive indices. Based on the characteristics of the substrate material, a substrate layer of 15nm SiO2 / 30nm Al2O3 was selected, and the proposed high-reflectivity layer is Ag / (Al2O3 / TiO2)m / SiO2.

[0024] The specific reflectivity can be simulated using Tfcalc software to determine the optimal reflectivity. The refractive indices of all materials were obtained through laboratory measurements and are in good agreement with theoretical values. The film system selection is as follows... Figure 1 As shown.

[0025] Step 102: Set the environmental parameters. During the design phase, the environmental parameters need to be set, including the incident and emission media of the membrane system, the substrate material and its thickness, the light source and its center wavelength and incident angle, and the wavelength and incident angle range. The proposed parameters for the membrane system are as follows: (21) The light source is "WHITE" and is incident perpendicularly from the air onto the surface of the film system, i.e., the incident angle is 0°. o .

[0026] (22) The wavelength range of light is 400-1000nm, with an interval of 1nm, and the center reference wavelength is the default 550nm.

[0027] (23) The substrate is aluminum with a thickness of 10mm.

[0028] (24) The detector is the default IDEAL, and the first surface is the front surface.

[0029] After completing the design, click "OK" to display the reflectivity curve of the aluminum substrate and begin the film system design. The environmental parameters can still be modified afterward.

[0030] Step 103 involves designing and optimizing the silver-based high-reflectivity film through simulation, which mainly consists of two steps: silver film thickness simulation and high-reflectivity film design and optimization.

[0031] Simulation analysis of silver film thickness: To select a suitable thickness for the Ag film, silver was first added as the front surface layer. Simulations were performed at 20nm intervals, with thicknesses ranging from 40-120nm, to compare reflectivity data. Simulations showed that above 425nm wavelength, the reflectivity of the Ag film increased with thickness. Above 80nm, the reflectivity was essentially consistent, but subtle differences remained. Therefore, an Ag film thickness of 100nm or more generally ensures good optical performance. For smooth substrates, the optical performance of the substrate is masked by the silver layer.

[0032] Design and Optimization Simulation of Silver-Based High-Reflectivity Film: The film system was designed using Tfcalc. Based on previous experimental research experience, a 15nm SiO2 / 30nm Al2O3 substrate was chosen. For the high-reflectivity layer, Ag was required to be at least 100nm to achieve reflectivity similar to bulk materials, and SiO2 needed to be sufficiently thick for moisture protection. Initially, both were set to 120nm, with Al2O3 and TiO2 thicknesses of λ0 / 4. Simulations were performed, resulting in a reflectivity layer system of 120nm Ag / (λ0 / 4)Al2O3 / (λ0 / 4)TiO2 / 120nm SiO2. Significant absorption was observed in the 400-450nm wavelength range. Based on this, an optimization target was set: reflectivity of 99%, optimizing the 400-450nm wavelength range. The Al2O3 and TiO2 reflectivity layers were set as optimizable, and the variable median function method was used for thickness optimization analysis. The Al2O3 thickness was optimized from 21 nm to 37 nm, and the TiO2 thickness was optimized from 15 nm to 48 nm. This improved reflectivity in the 400-550 nm wavelength range, achieving an average reflectivity of over 97.5%. The simulation results were good, for example... Figure 3 As shown.

[0033] Based on the simulation results above, while keeping the substrate layer unchanged, other film systems as shown in Table 1 were designed and optimized, and compared with them. The reflectivity effects are as follows: Figure 4 As shown, the reflectivity of the single-dielectric film 90nm Al2O3 above 550nm is about 1.5% lower than other designs; the double-dielectric film 30nm Al2O3 / 150nm SiO2 has poor reflectivity in the 400-500nm band, and the reflectivity in the 400nm band is even less than 90%, and it cannot be optimized to high reflectivity, but the reflectivity above 550nm is better than the original design; TiO2 and Ta2O5 with similar refractive indices were compared with the same optical thickness, and the results showed that the reflectivity of the 120nm Ag / 37nm Al2O3 / 48nm TiO2 / 120nm SiO2 reflective layer was good near 400-450nm.

[0034] Table 1 High-reflectivity layer design

[0035] The optical thickness of 53nm Ta2O5 is the same as that of 48nm TiO2.

[0036] Based on the design of a single reflective layer, a pair of Al2O3 and TiO2 films were added for design optimization. The optimization target was set at 400-900 nm, with a target reflectivity of 98.5%. The optimized design is as follows: Figure 5 As shown, the 400-700nm band is slightly improved compared to Design 1, but the improvement is less than 1%. Due to the absorption in actual applications, it may not really improve reflectivity. At the same time, the coating process will be more complicated and the error tolerance will be reduced.

[0037] In one embodiment, Design 5 can also be adopted: a reflective layer of 120nm Ag / 59nm Al2O3 / 54nm TiO2 / 45nm Al2O3 / 34nm TiO2 / 120nm SiO2. Design 5 is based on the reflective layer of Design 1, and considers adding a pair of Al2O3 and TiO2 film layers for design optimization. The multi-layer stacking can improve the reflectivity.

[0038] Step 104: Perform simulation for fine-tuning of dielectric film thickness.

[0039] Considering the thickness control errors during actual coating, a 120nm film thickness is sufficient for the Ag layer. Even with slight thickness variations, the impact on actual reflectivity is negligible. For dielectrics Al2O3, TiO2, and SiO2, fine-tuning is needed within the originally designed range to explore the potential impact of errors during actual coating. Low impact indicates high design tolerance, making the designed film system more suitable for actual product requirements. Furthermore, re-simulating the dielectric film thickness is necessary during the design phase to achieve higher reflectivity.

[0040] Adjusting all three dielectric layers simultaneously would require too many simulation sets. Therefore, given that the 37nm Al2O3 and 48nm TiO2 dielectric layers have similar thicknesses and are both high- and low-refractive-index antireflective layers, we first optimized these two layers. The Al2O3 layer thickness was set at 35-40nm, and the TiO2 thickness at 45-50nm. By taking the maximum and minimum values ​​of the two film thicknesses for comprehensive optimization, the simulation results are as follows. Figure 6 As shown: Simulation results show that the reflectivity is worst when the Al2O3 and TiO2 layer thicknesses are 35nm and 45nm, respectively, and best when they are 40nm and 50nm. The reflectivity in the other two cases is almost the same as the original value. Furthermore, the wavelength range with the largest reflectivity difference is around 525nm, with a difference of approximately 0.5%, which is very small. Therefore, for Al2O3 and TiO2 layers, the reflectivity difference is extremely small when the film thickness error is less than 5nm. For a well-calibrated coating equipment, such a large error would not occur. This minimal reflectivity difference also indicates the feasibility of subsequent controlled variable experiments. Under the condition of keeping the film thickness constant, errors generated by the coating equipment itself have almost no impact on the experimental results from two different depositions. Based on Al2O3 and TiO2 layers with thicknesses of 40 nm and 50 nm respectively, the SiO2 layer was further fine-tuned in simulations, with the thickness adjusted within the range of 110-130 nm. Its reflectivity was as follows: Figure 7 As shown: Simulation results show that the reflection difference of this high-reflectivity film system is about 0.5% within the range of 120±10nm SiO2 film thickness difference. When the SiO2 film thickness is large, the reflectivity is better at wavelengths below 550nm and above 800nm. When the thickness is small, the reflectivity is better between wavelengths of 550-800nm. Both have their advantages, so the original value of 120nm is still to be selected.

[0041] Simulations investigated the effect of refractive index. The refractive indices of the dielectric layers Al₂O₃, TiO₂, and SiO₂ may differ slightly from the original data during actual deposition. For electron beam evaporation, the refractive index of the TiO₂ and SiO₂ films increases with increasing temperature and decreases with increasing oxygen content. The refractive index of the SiO₂ film changes little, remaining around 1.44-1.465 at 550 nm, which can be considered negligible. However, for the TiO₂ film, the refractive index at 550 nm ranges from as low as 1.85 to as high as 2.2. If the TiO₂ film is bombarded with an ion source with an energy of 180 eV, its refractive index increases, reaching a maximum of around 2.36. The change in the refractive index of TiO₂ leads to a change in the reflectivity of the high-reflectivity film as follows: Figure 8 As shown, changes in the refractive index of the TiO2 film above 650 nm have almost no effect on the reflectivity of the original high-reflectivity film. In the 400-550 nm wavelength range, the impact of the refractive index on the TiO2 film is also not significant. At a refractive index of 2.4, the reflectivity of the high-reflectivity film is only about 2% higher than that at a refractive index of 1.8. Simulation results show that even with a refractive index as low as 1.8, the reflectivity of the high-reflectivity film can still reach over 95.5%. In actual coating processes, an appropriate oxygen content is selected, suggesting that changes in the refractive index of the TiO2 film will cause even smaller changes in reflectivity.

[0042] The high-reflectivity film designed above only shows the reflectivity under perpendicular incidence at a center reference wavelength of 550nm. In practical applications, this reflectivity should not be used as a general guideline. The situation under oblique incidence must also be considered. The experimental results for measuring the reflectivity of the coated product are under oblique incidence conditions. Therefore, to explore the optical practicality of this film system, simulations under oblique incidence and polarization conditions are necessary.

[0043] As above Figure 9 As shown, when the incident angle is between 0-75° o At this time, the 120nm Ag / 40nm Al2O3 / 50nm TiO2 / 120nm SiO2 high-reflectivity film still maintains a reflectivity of over 97%, with an incident angle of 0-30°. o At this time, the reflectivity curve hardly changes. (The incident angle is greater than 60°.) o At that time, the reflectivity curve fluctuates more.

[0044] like Figure 10 , Figure 11 As shown, for polarized light incident at an angle of 15°, o The reflectivity of S- and P-polarized light is almost identical to the average value. However, the incident angle is 60°. o The reflectivity of S-polarized and P-polarized light differs significantly, with a difference of over 3% in the 400nm band and reaching 2% in the 700nm band. P-polarized light has a lower reflectivity, dropping to 95% in the 400nm band. The increased fluctuation in the reflectivity curve as the incident angle increases is due to the growing difference between S-polarized and P-polarized light.

[0045] The high-reflectivity film was ultimately determined to be 120nm Ag / 40nm Al2O3 / 50nm TiO2 / 120nm SiO2. This yielded a high-reflectivity film system with a reflectivity exceeding 97% (Sub / 15nm SiO2 / 30nm Al2O3 / 120nm Ag / 40nm Al2O3 / 50nm TiO2 / 120nm SiO2).

[0046] Step 105 involves preparing a silver-based high-reflectivity film, specifically including: (51) Pre-melt the dielectric film. Set up three film systems on the machine: substrate layer SiO2 15nm, Al2O3 30nm; silver film 120nm; dielectric layer Al2O3 40nm, TiO2 50nm, SiO2 120nm. Check the parameters of the coating settings. Add silver film material (add it each time).

[0047] (52) Evacuate to 3x10 -3Pa, turn on the power supply current to 6mA, power supply speed 15r / min. Turn on the ion source and bombard the substrate for 10min.

[0048] (53) No sample is taken and the process does not need to be stopped when depositing the SiO2 15nm and Al2O3 30nm substrate layers. Wait for the vacuum level to reach 3x10 again. -3 Pa.

[0049] (54) The baffle plate blocks the pre-melting of the silver film.

[0050] (55) After completing the deposition of a single layer of silver film, immediately record the time with a stopwatch. The steps for single-layer silver deposition are the same as above. The bombardment is completed in about 2 minutes (70s + 45s). No sample is taken or the machine is stopped. The deposition thickness is 120nm.

[0051] (56) Turn off the Ar gas, adjust the ion source voltage to 180V, turn off the ion source, turn on the working current, manually open the baffle to block it, adjust the machine to the dielectric layer, press start, the machine will automatically switch to crucible deposition, stop deposition after confirming that there is no problem, adjust the machine to the dielectric layer again, and release the baffle.

[0052] (57) When the stopwatch reaches 10 min, turn on Ar and press the start button to begin the deposition of the dielectric layer. The parameters are shown in Table 1 and Table 2. Turn on the ion source with the following parameters: voltage 180V, current 3A, Al2O3 deposition at 40nm, velocity 4Å / s, beam current 99-113mA, and adjust the Ar flow rate to 3.9sccm / s to make the total pressure 1x10 -2 After Al2O3 deposition, the Ar gas was turned off, and the instrument automatically switched to crucible deposition of TiO2 at 250 nm. The deposition rate was 2 Å / s, and the beam current was 125-140 mA. O2 was then turned on, and the O2 flow rate was adjusted to 18 sccm / s to achieve a total pressure of 2 x 10⁻⁶. -2 Pa, O2 gas off, the machine automatically switches crucible to deposit SiO2 at 120nm, deposition rate 6Å / s, beam current 33-35mA, O2 on, adjust O2 flow rate to 7sccm / s to achieve a total pressure of 1x10 -2 Pa, after deposition is complete, O2 is turned off, ion source, electron gun scanning power supply, gun filament current.

[0053] (58) After 10 minutes, release the gas, take out the sample, put it into a numbered sample box, and vacuum seal it for subsequent testing.

[0054] In summary, the structure of the silver-based high-reflectivity film is: 15nm SiO2 / 30nm Al2O3 / 120nm Ag / 40nm Al2O3 / 50nm TiO2 / 120nm SiO2. The substrate layer is 15nm SiO2 / 30nm Al2O3, the high-reflectivity layer is 120nm Ag, and the anti-reflection layer is 40nm Al2O3 / 50nm TiO2 / 120nm SiO2. Finally, the silver-based high-reflectivity film exhibits a reflectivity greater than 95% in the 400-1000nm wavelength range. Figure 12 As shown.

[0055] The design is based on the optical theory of thin metal films. Multiple dielectric layers need to be deposited on the silver film for protection, while maximizing the reflectivity of the silver film. Different dielectric film systems result in different reflectivities. To ensure the highest possible reflectivity, multiple silver-based films need to be designed for comparison and selection. During the design process, corrosion resistance and durability must be considered. Simultaneously, the film structure should not be too complex, otherwise there will be too many variables and the fabrication process will be complicated. Several high-reflectivity films were designed using Tfcalc software for comparison and optimization. Based on this, the dielectric film layers were fine-tuned, showing that possible errors in the dielectric layer during deposition do not have a significant impact. A high-reflectivity film system with a reflectivity of over 95% was obtained: Sub / 15nm SiO2 / 30nm Al2O3 / 120nm Ag / 40nm Al2O3 / 50nm TiO2 / 120nm SiO2. Simulations were conducted to address potential changes in the refractive index of the dielectric layer and oblique incidence during coating. These simulations demonstrated that even under adverse conditions, the film system can still maintain a reflectivity of over 95%, exhibiting high tolerance and providing a sound theoretical basis for practical coating. The silver-based high-reflectivity film actually prepared through simulation showed an average reflectivity exceeding 50% in the 400-1000nm wavelength range, proving that this method can indeed produce silver-based high-reflectivity films that meet the required conditions and save on manpower and resources.

[0056] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0057] The present invention also provides a storage medium, which is a computer-readable storage medium storing a computer program thereon, the computer program being executable when it runs. Figure 2The method shown may include some or all of the steps. The storage medium may include read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc. The storage medium may also include non-volatile memory or non-transitory memory, etc.

[0058] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer program are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data provider to another website, computer, server, or data provider via wired or wireless means.

[0059] The embodiments of the present invention have been described in detail above. Specific implementation methods have been used to illustrate the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and systems of the present invention, and are merely some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention, and the content of this specification should not be construed as a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A silver-based high-reflectivity film, characterized in that, The silver-based high-reflectivity film includes a substrate, a substrate layer, a high-reflectivity layer, and an anti-reflection layer. The substrate is made of aluminum alloy. The substrate layer is located on the substrate and includes a first SiO2 layer and a first Al2O3 layer. The first Al2O3 layer is in close contact with the high-reflectivity layer. The high-reflectivity layer is located between the substrate layer and the anti-reflection layer. The high-reflectivity layer is a silver film. The anti-reflection layer includes a dielectric film system with alternating high and low refractive indices and a second SiO2 layer located on the outermost layer to prevent moisture and corrosion. The dielectric film system with alternating high and low refractive indices consists of a second Al2O3 layer and a first TiO2 layer from bottom to top.

2. The silver-based high-reflectivity film according to claim 1, characterized in that, The thickness of the first SiO2 layer is 15nm, the thickness of the first Al2O3 layer is 30nm, the thickness of the high reflectivity layer is 120nm, the thickness of the second Al2O3 layer is 40nm, the thickness of the first TiO2 layer is 50nm, and the thickness of the second SiO2 layer is 120nm.

3. A method for preparing a silver-based high-reflectivity film, characterized in that, The method is used to prepare the silver-based high-reflectivity film according to claim 1, comprising: Step 1: Select the film material and determine the structure of the silver-based high-reflectivity film; Step 2: Set the environmental parameters; Step 3: Perform design and optimization simulation of the silver-based high-reflectivity film; Step 4: Perform a simulation to fine-tune the thickness of the silver-based high-reflectivity film; Step 5: Prepare the silver-based high-reflectivity film.

4. The method for preparing a silver-based high-reflectivity film according to claim 3, characterized in that, In step 1, when selecting the film material, Al2O3 is selected as the close-fitting layer of the silver film, and SiO2 is selected as the outermost layer with a thickness of more than 100nm to play a role in preventing moisture and corrosion. Al2O3 is selected as the low refractive index layer and TiO2 is selected as the high refractive index layer. The silver-based high reflectivity film is determined to include a substrate, a substrate layer, a high reflectivity layer and an anti-reflectivity layer. The substrate is made of aluminum alloy. The substrate layer is located on the substrate and includes a first SiO2 layer and a first Al2O3 layer. The first Al2O3 layer is close to the high reflectivity layer. The high reflectivity layer is located between the substrate layer and the anti-reflectivity layer. The high reflectivity layer is a silver film. The anti-reflectivity layer includes a dielectric film system with alternating high and low refractive indices and a second SiO2 layer located on the outermost layer to play a role in preventing moisture and corrosion. The dielectric film system with alternating high and low refractive indices consists of a second Al2O3 layer and a first TiO2 layer from bottom to top.

5. The method for preparing the silver-based high-reflectivity film according to claim 3, characterized in that, In step 2, when setting environmental parameters, it is necessary to set the incident and ingress media of the membrane system, the substrate material and its thickness, the light source and its center wavelength and incident angle, and the wavelength and incident angle range.

6. The method for preparing a silver-based high-reflectivity film according to claim 4, characterized in that, In step 3, a simulation analysis of the silver film thickness is performed. First, silver is added separately as the front surface film layer, with a thickness of 40-120nm. The design simulation is carried out in 20nm increments to obtain reflectivity data. The simulation shows that the reflectivity of the silver film increases with the increase of the thickness above 425nm. The reflectivity is basically the same when the silver film thickness is above 80nm, but there are still slight differences. Therefore, the silver film thickness is selected to be above 100nm to ensure good optical performance of the silver film.

7. The method for preparing a silver-based high-reflectivity film according to claim 6, characterized in that, In step 3, when designing and optimizing the silver-based high-reflectivity film, the substrate layer is selected as 15nm SiO2 / 30nm Al2O3. The initial thickness of the silver film of the high-reflectivity layer and the thickness of the second SiO2 layer are set to 120nm. The thickness of the second Al2O3 layer and the first TiO2 layer are λ0 / 4, which is a quarter wavelength. The simulation shows that the reflective layer film system is 120nm Ag / (λ0 / 4)Al2O3 / (λ0 / 4)TiO2 / 120nm SiO2. During the simulation, significant absorption was found in the 400-450nm wavelength band. Based on this, an optimization target was set: reflectivity, with a target value of 99%, and optimization in the 400-450nm wavelength band. The second Al2O3 layer and the first TiO2 layer were set as optimizable, and the variable median function method was used for optimization analysis of the thickness. Then, based on the simulation results, while keeping the substrate layer unchanged, the design of the dielectric film system with alternating high and low refractive indices was changed for optimization and comparison. The reflective layer film system was determined to be 120nm Ag / 37nm Al2O3 / 48nm TiO2 / 120nm SiO2.

8. The method for preparing a silver-based high-reflectivity film according to claim 7, characterized in that, In step 4, the second Al2O3 layer and the first TiO2 layer are first optimized. The thickness of the second Al2O3 layer is 35-40 nm, and the thickness of the first TiO2 layer is 45-50 nm. By taking the maximum and minimum values ​​of the film thicknesses of the two layers for comprehensive optimization, the simulation results determine that the thickness of the second Al2O3 layer is 40 nm, and the reflectivity is best when the thickness of the first TiO2 layer is 50 nm. Then, based on the thickness of the second Al2O3 layer being 40 nm and the thickness of the first TiO2 layer being 50 nm, the second SiO2 layer is fine-tuned through simulation. The thickness is fine-tuned within the range of 110-130 nm, and the simulation results determine that the thickness of the second SiO2 layer is 120 nm. Finally, simulations are performed for oblique incidence and polarization conditions to determine that the reflective layer film system is 120 nm Ag / 40 nm Al2O3 / 50 nm TiO2 / 120 nm SiO2.

9. The method for preparing a silver-based high-reflectivity film according to claim 8, characterized in that, Step 5 includes: Step 51: Pre-melt the first SiO2 layer (15nm) and the first Al2O3 layer; set the coating parameters of the silver-based high-reflectivity film and add silver film material; Step 52: Perform vacuuming and turn on the ion source to bombard the substrate; Step 53: Deposit the first SiO2 layer (15 nm) and the first Al2O3 layer (30 nm); Step 54: Install the baffle plate to pre-melt the silver film of the high-reflectivity layer; Step 55: Complete the deposition of the silver film of the high reflectivity layer, with a deposition thickness of 120 nm; Step 56: Turn off the ion source and release the baffle. Step 57: Turn on the ion source and deposit the second Al2O3 layer at 40 nm. After depositing the second Al2O3 layer, deposit the first TiO2 layer at 50 nm. After depositing the first TiO2 layer, deposit the second SiO2 layer at 120 nm.

10. The method for preparing a silver-based high-reflectivity film according to claim 9, characterized in that, In step 51, when setting the coating parameters of the silver-based high-reflectivity film, the first SiO2 layer is set to 15nm, the first Al2O3 layer to 30nm, the high-reflectivity layer to 120nm, the second Al2O3 layer to 40nm, the first TiO2 layer to 50nm, and the second SiO2 layer to 120nm.

Images