High-transmittance optical coating material and preparation method thereof

Abstract

The present application relates to the technical field of optical coating materials, in particular to a high-transmittance optical coating material and a preparation method thereof.The present application overcomes the technical problems of low transmittance and poor adhesion of the existing optical coating materials.The present application performs ion cleaning and HMDS in-situ plasma grafting on an optical substrate, deposits a ZrO2-doped Nb2O5 stress buffer layer by high-power pulsed magnetron sputtering, constructs a gradient refractive index functional layer by double-target variable-power co-sputtering, deposits a porous SiO2-doped MgF2 surface layer under high pressure, and finally obtains the optical coating material through high-concentration ozone annealing treatment.The present application significantly enhances the adhesion of the material through chemical bonding and high-energy bombardment, eliminates interface reflection by using a gradient structure, and matches the refractive index by using a surface micro-nano structure.

Description

Technical Field

[0001] This invention relates to the field of optical coating materials technology, specifically to a high-transmittance optical coating material and its preparation method. Background Technology

[0002] In the fields of modern precision optics, photovoltaic power generation, and display panels, optical coating is key to improving system luminous efficiency. Physical vapor deposition (PVD), especially magnetron sputtering, is typically used to alternately deposit high-refractive-index (e.g., TiO2, Nb2O5) and low-refractive-index (e.g., SiO2, MgF2) materials on the surface of glass or resin substrates. This utilizes the principle of thin-film interference to reduce surface reflection and improve light transmittance.

[0003] Although existing optical coating technologies are relatively mature, two major bottlenecks remain in achieving high transmittance and environmental stability. First, transmittance limitations (light loss): Traditional multilayer coatings exhibit significant interlayer interfaces, where lattice mismatch and roughness lead to light scattering loss. Furthermore, materials like titanium oxides used to achieve high refractive indices are prone to generating absorption centers under oxygen-deficient deposition conditions, resulting in decreased transmittance of the final product. Second, poor adhesion (film peeling): The coefficients of thermal expansion (CTE) of high- and low-refractive-index materials differ significantly from those of the substrate, accumulating substantial internal stress during deposition. Especially under humid, hot, or extreme temperature shock environments, the coating material is highly susceptible to cracking or peeling from the substrate surface due to stress release, failing to meet the demands of harsh environments.

[0004] To address this, a high-transmittance optical coating material and its preparation method are proposed. Summary of the Invention

[0005] The purpose of this invention is to design a high-transmittance optical coating material and its preparation method. This invention involves ion cleaning and HMDS in-situ plasma grafting of the optical substrate; deposition of a ZrO2-doped Nb2O5 stress buffer layer using high-power pulsed magnetron sputtering; construction of a gradient refractive index functional layer through dual-target variable-power co-sputtering; deposition of a porous SiO2-doped MgF2 surface layer under high pressure; and finally, high-concentration ozone annealing to obtain the optical coating material. Ultimately, this invention significantly enhances the adhesion of the material through chemical bonding and high-energy bombardment, eliminates interface reflections through gradient structures, and matches the refractive index to the surface micro / nano structures.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing a high-transmittance optical coating material, comprising the following steps:

[0008] The optical substrate is subjected to surface activation and ion cleaning to obtain a pretreated substrate. A stress buffer layer is deposited on the pretreated substrate using a zirconium oxide-doped niobium oxide ceramic target. A functional layer is deposited on the surface of the stress buffer layer by dual-target co-sputtering. A surface layer is deposited on the surface of the functional layer using a magnesium fluoride-doped silicon dioxide target. After post-treatment, an optical coating material is obtained.

[0009] Preferably, the specific process of surface activation and ion cleaning is as follows: the optical substrate is ultrasonically cleaned for 30 minutes and then dried, and then placed in a vacuum chamber, with the base vacuum level evacuated to 2×10⁻⁶. -4 Pa-4×10 -4 Pa; The optical substrate is heated to 120℃ and held at that temperature for 10 min to remove gas; A mixture of argon (Ar) and oxygen (O2) is introduced, with an Ar flow rate of 15-25 sccm and an O2 flow rate of 10 sccm; The Kaufman ion source is turned on (voltage 300V, current 0.5A) to clean the surface of the optical substrate for 1-5 min, and hexamethyldisilazane (HMDS) vapor is introduced in the last 30 s for in-situ plasma grafting to obtain a pretreated substrate; The hexamethyldisilazane (HMDS) vapor flow rate is 1-3 sccm; The optical substrate can be optical glass; The HMDS vapor is obtained by heating liquid HMDS to 55℃ to vaporize it, and argon is introduced at the same time as HMDS vapor, while oxygen is turned off.

[0010] Preferably, the stress buffer layer is prepared by: using high-power pulsed magnetron sputtering, turning on the power supply of the zirconia-doped niobium oxide ceramic target, and depositing a stress buffer layer with a thickness of 13-17 nm on the surface of the pretreated substrate; the sputtering pressure is 0.3-0.5 Pa (the introduced gas is a mixture of Ar and O2, with an Ar flow rate of 40 sccm and an O2 flow rate of 15 sccm), the pulse frequency is 450-550 Hz, the pulse width is 100 μs, and the peak power density is 1.3-1.7 kW / cm². 2 The substrate bias voltage is -200V; the zirconia-doped niobium oxide ceramic target is made by sintering niobium oxide and zirconia, with a weight ratio of niobium oxide to zirconia of 9:1.

[0011] Preferably, the method for preparing the functional layer is as follows: simultaneously turn on the zirconia-doped niobium oxide ceramic target and the magnesium fluoride-doped silica target, and control the power of the two cathode targets through a program. In the initial stage, the power of the zirconia-doped niobium oxide ceramic target is gradually reduced from 5 kW to 3-4 kW, and the power of the magnesium fluoride-doped silica target is gradually increased from 0 kW to 0.6-0.8 kW, with a time of 450-550 s; in the intermediate stage, the power of the zirconia-doped niobium oxide ceramic target is gradually reduced to 1-2 kW, and the power of the magnesium fluoride-doped silica target is gradually increased to 1.5-2.5 kW, with a time of 450-550 s. Final stage: The power of the zirconia-doped niobium oxide ceramic target is gradually reduced to 0 kW, while the power of the magnesium fluoride-doped silica target is gradually increased to 2.5-3.5 kW over a period of 500 s; the substrate bias voltage is reduced from -150 V to -50 V; the introduced gas is a mixture of Ar and O2, with the Ar flow rate remaining constant at 40 sccm and the O2 flow rate gradually decreasing from 25 sccm to 5 sccm; the magnesium fluoride-doped silica target is prepared by sintering silica and magnesium fluoride, with a weight ratio of silica to magnesium fluoride of 19:1; the final functional layer deposition thickness is 440-460 nm.

[0012] Preferably, the surface layer is prepared by: using RF magnetron sputtering, turning on only the magnesium fluoride-doped silicon dioxide target, introducing a mixed gas of Ar and O2, with an Ar flow rate of 100-120 sccm and an O2 flow rate of 4 sccm, increasing the sputtering pressure to 2.5 Pa, turning off the substrate bias, controlling the power to 1.0 kW, and depositing a surface layer with a thickness of 80-100 nm on the surface of the functional layer.

[0013] Preferably, the post-treatment process is as follows: stop sputtering, maintain vacuum, turn on the heater to 150°C, and introduce ozone at a concentration of 110-130 g / Nm³. 3 Maintain the cavity pressure at 2000Pa, process for 10-20 minutes, cool to below 60℃ and remove from the cavity to obtain the optical coating material.

[0014] Another aspect of the present invention provides a high-transmittance optical coating material, which includes a stress buffer layer, a functional layer and a surface layer.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] This invention introduces hexamethyldisilazane (HMDS) vapor into the ion cleaning stage for in-situ plasma grafting, constructing a chemically active organic-inorganic transition layer on the surface of an inorganic substrate, which acts as a chemical anchor. Combined with a stress buffer layer deposited by high-power pulsed magnetron sputtering under high bias voltage, and the formation of a pseudo-diffusion layer by bombarding the surface with high-energy particles, this invention achieves a dual synergy of physical bonding and chemical bonding, solving the problems of easy detachment and poor adhesion of optical coatings in humid and hot environments.

[0017] This invention constructs a gradient refractive index structure with a continuous change in refractive index from high to low during the functional layer deposition process through precise dual-target power linear offset adjustment and dynamic oxygen flow control. This structure eliminates the abrupt interface caused by the alternation of high and low refractive index materials in traditional multilayer film systems, fundamentally preventing Fresnel reflection loss at the interface and avoiding interlayer stress concentration caused by differences in thermal expansion coefficients, while improving optical performance and mechanical stability.

[0018] This invention employs a high-pressure (2.5 Pa) and low-power radio frequency sputtering process during surface layer deposition. The thermal effect of gas molecules allows sputtered particles to soft-land, self-assembling on the film surface to form a loose, porous nanopillar structure. This structure effectively reduces the material's equivalent refractive index, perfectly matching it with the refractive index of air, resulting in an anti-reflective effect and significantly increasing the light flux into the film.

[0019] This invention involves doping niobium oxide with zirconium oxide, utilizing the lattice distortion effect of zirconium atoms to suppress the crystallization of niobium oxide, maintaining its amorphous state, reducing grain boundary scattering, and improving the film hardness. Furthermore, it involves doping silicon dioxide with magnesium fluoride, which, while maintaining the stability of the silicon dioxide network structure, further reduces the refractive index at the low-refractive-index end. This synergistic modification between materials not only optimizes optical parameters but also enhances the wear resistance of the film.

[0020] This invention introduces high-concentration ozone for thermal annealing during the post-processing stage. Utilizing ozone's extremely strong penetrating and oxidizing properties, it penetrates the porous structure of the surface, allowing for in-situ repair of trace oxygen vacancies that may arise from the deep layers due to HiPIMS high-energy deposition. This process eliminates light absorption centers in the film (such as yellowing) and releases residual stress accumulated during deposition, further ensuring the high light transmittance and mechanical strength of the coated material. Attached Figure Description

[0021] Figure 1 The diagram shows the refractive index and haze performance of Examples 1, 10-13 and Comparative Examples 9-11 of the present invention. 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. 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 are within the scope of protection of the present invention.

[0023] For details, please refer to [link / reference]. Figure 1 This invention provides a high-transmittance optical coating material and its preparation method, the technical solution of which is as follows:

[0024] Example 1

[0025] The optical substrate was ultrasonically cleaned for 30 minutes and then dried. It was then placed in a vacuum chamber, and the base vacuum was evacuated to 3 × 10⁻⁶. -4 Pa; The optical substrate was heated to 120℃ and held at that temperature for 10 min to remove gas; A mixture of argon (Ar) and oxygen (O2) gas was introduced, with an Ar flow rate of 20 sccm and an O2 flow rate of 10 sccm; The Kaufman ion source was turned on (voltage 300V, current 0.5A) and the surface of the optical substrate was cleaned for 3 min, and hexamethyldisilazane (HMDS) vapor was introduced in the last 30 s for in-situ plasma grafting to obtain a pretreated substrate; the hexamethyldisilazane (HMDS) vapor flow rate was 2 sccm;

[0026] High-power pulsed magnetron sputtering was used to deposit a 15 nm thick stress buffer layer on the pretreated substrate surface by turning on the zirconia-doped niobium oxide ceramic target power supply. The sputtering gas pressure was 0.4 Pa (the introduced gas was a mixture of Ar and O2, with an Ar flow rate of 40 sccm and an O2 flow rate of 15 sccm), the pulse frequency was 500 Hz, the pulse width was 100 μs, and the peak power density was 1.5 kW / cm². 2 The base bias voltage is -200V;

[0027] Simultaneously, the zirconia-doped niobium oxide ceramic target and the magnesium fluoride-doped silica target were activated. The power of the two cathode targets was controlled by a program. In the initial stage, the power of the zirconia-doped niobium oxide ceramic target gradually decreased from 5 kW to 3.5 kW, while the power of the magnesium fluoride-doped silica target gradually increased from 0 kW to 0.7 kW over 500 s. In the intermediate stage, the power of the zirconia-doped niobium oxide ceramic target gradually decreased to 1.5 kW, while the power of the magnesium fluoride-doped silica target gradually increased to 2 kW over 500 s. In the final stage, the power of the zirconia-doped niobium oxide ceramic target gradually decreased to 0 kW, while the power of the magnesium fluoride-doped silica target gradually increased to 3 kW over 500 s. The substrate bias voltage decreased from -150 V to -50 V. The introduced gas was a mixture of Ar and O2, with the Ar flow rate constant at 40 sccm and the O2 flow rate gradually decreasing from 25 sccm to 5 sccm. The final functional layer deposition thickness was 450 nm.

[0028] RF magnetron sputtering was used, with only the magnesium fluoride-doped silicon dioxide target turned on. The gas introduced was a mixture of Ar and O2, with an Ar flow rate of 110 sccm and an O2 flow rate of 4 sccm. The sputtering pressure was increased to 2.5 Pa, the substrate bias was turned off, and the control power was 1.0 kW. A surface layer with a thickness of 90 nm was deposited on the surface of the functional layer.

[0029] Stop sputtering, maintain vacuum, turn on the heater to 150°C, and introduce ozone at a concentration of 120 g / Nm³. 3 Maintain the cavity pressure at 2000 Pa, process for 15 min, cool to below 60 °C and remove from the cavity to obtain the optical coating material.

[0030] Examples 2-5 refer to the parameter conditions in Example 1, with specific differences shown in Table 1.

[0031] Table 1 Parameters and conditions for Examples 1-5

[0032] Example Background vacuum level / Pa Ar flow rate / sccm Ion cleaning time / min HMDS vapor flow rate / sccm Stress buffer layer thickness / nm Sputtering pressure / Pa Pulse frequency / Hz Peak power density / kW / cm 2 ]] Example 1 3 x 10 -4 ]] 20 3 2 15 0.4 500 1.5 Example 2 2 x 10 -4 ]] 15 1 1 13 0.3 450 1.3 Example 3 2 x 10 -4 ]] 18 2 3 14 0.5 480 1.4 Example 4 4 x 10 -4 ]] 22 4 1 16 0.5 520 1.6 Example 5 <![CDATA[4×10 -4 ]]> 25 5 3 17 0.3 550 1.7

[0033] Comparative Example 1 follows the same parameters and conditions as in Example 1, except that the optical substrate is not subjected to ultrasonic cleaning before subsequent processing.

[0034] Comparative Example 2 follows the same parameters and conditions as in Example 1, except that HMDS vapor is not introduced at the end of the ion cleaning process.

[0035] Comparative Example 3 follows the same parameters and conditions as in Example 1, except that a zirconia target is used when preparing the stress buffer layer.

[0036] Comparative Example 4 follows the same parameters and conditions as in Example 1, except that a niobium oxide target is used when preparing the stress buffer layer.

[0037] Experimental Example 1: Adhesion, Hardness, and Abrasion Resistance Tests

[0038] The adhesion of Examples 1-5 and Comparative Examples 1-4 was tested according to GB / T 9286-2021 standard; the hardness of Examples 1-5 and Comparative Examples 1-4 was tested according to GB / T 6739-2006 standard; wear tests were conducted on Examples 1-5 and Comparative Examples 1-4, and the wear amount was calculated by measuring the mass change before and after wear. The results are shown in Table 2.

[0039] Table 2 Adhesion, hardness and abrasion resistance tests of Examples 1-5 and Comparative Examples 1-4

[0040] Example Adhesion / Grade Hardness / H Wear amount / mg / h Example 1 0 7 0.42 Example 2 0 7 0.47 Example 3 0 7 0.45 Example 4 0 6 0.46 Example 5 0 7 0.43 Comparative Example 1 4 3 1.85 Comparative Example 2 2 6 0.82 Comparative Example 3 2 7 0.65 Comparative Example 4 0 5 0.91

[0041] Table 2 shows that Comparative Example 1, which underwent subsequent processing without ultrasonic cleaning, had poor adhesion test results and significantly reduced wear resistance (wear amount as high as 1.85 mg / h). This is because optical substrates typically have trace amounts of oil, dust, or other organic contaminants remaining on their surfaces. Without ultrasonic cleaning to remove these physical impurities, even with subsequent ion cleaning, the film layer is actually deposited on a loose layer of contaminants rather than directly bonded to the substrate. This "virtual contact" makes the film layer extremely prone to peeling off in sheets during cross-cut adhesion tests and friction. Comparative Example 2 did not introduce HMDS vapor during the ion cleaning stage, resulting in a decrease in adhesion to level 2 and an increase in wear resistance to 0.82 mg / h. Compared to Example 1, Comparative Example 2 relied solely on physical bombardment (ion cleaning) to activate the surface. Although this could generate a certain degree of roughness and dangling bonds, it lacked the "organic-inorganic" chemical bridge constructed by the active silicon groups generated by HMDS decomposition. Under high-stress environments such as humid heat or mechanical friction, simple physical bonding was insufficient to resist shear forces, leading to a weakening of the bonding strength between the film layer and the substrate interface. Comparative Example 3 used a pure zirconia target when preparing the stress buffer layer. Although its hardness remained at a high level (7H), the adhesion dropped to level 2, and the wear amount (0.65mg / h) was higher than that of the Example. This is because although the pure zirconia film has high hardness, its internal stress is large, and its coefficient of thermal expansion is significantly different from that of the bottom of the subsequent niobium-rich gradient functional layer. This mismatch in material properties leads to a large interlayer stress between the buffer layer and the functional layer, making the film system brittle. When subjected to external friction, it is prone to microcrack propagation and brittle spalling, and cannot play a good stress relief role. Comparative Example 4 used a pure niobium oxide target when preparing the stress buffer layer. The results showed that its hardness decreased to 5H and the wear rate increased significantly to 0.91 mg / h. This is because the hardness of pure niobium oxide material itself is lower than that of the composite material doped with zirconium oxide. It is also prone to crystallization when deposited in thicker layers or heated, resulting in grain boundary defects. The lack of zirconium oxide as a lattice stabilizer and hardener makes the buffer layer, which serves as the "foundation" of the film system, too weak and unable to provide sufficient mechanical support for the upper gradient functional layers. In the wear resistance test, the deformation of the substrate led to the collapse of the upper film layer or accelerated wear, demonstrating the necessity of Zr-Nb dual-component synergy for improving the overall mechanical properties of the film system.

[0042] Examples 6-9 refer to the parameter conditions in Example 1, with specific differences shown in Table 3.

[0043] Table 3 Parameter conditions for Examples 1 and 6-9

[0044] Example Power reduction / kW of zirconium oxide-doped niobium oxide ceramic target in the initial stage Power rise / kW of magnesium fluoride-doped silicon dioxide target in the initial stage Initial stage processing time / s Power reduction / kW of zirconium oxide-doped niobium oxide ceramic target in the intermediate stage Power rise / kW of magnesium fluoride-doped silicon dioxide target in the intermediate stage Intermediate stage processing time / s The final stage power rise of the magnesium fluoride-doped silicon dioxide target / kW Thickness of functional layer / nm Example 1 3.5 0.7 500 1.5 2 500 3 450 Example 6 3 0.6 450 1 1.5 550 2.5 440 Example 7 4 0.6 480 1 2.5 520 3.5 445 Example 8 3 0.8 520 2 2.5 480 3.5 455 Example 9 4 0.8 550 2 1.5 450 2.5 460

[0045] Comparative Example 5 follows the same parameters and conditions as in Example 1, except that it only undergoes the initial stage of processing.

[0046] Comparative Example 6 follows the same parameters and conditions as in Example 1, except that it only undergoes intermediate processing.

[0047] Comparative Example 7 follows the same parameters and conditions as in Example 1, except that it only undergoes the final stage of processing.

[0048] Comparative Example 8 follows the same parameters and conditions as in Example 1, except that the weight ratio of silicon dioxide to magnesium fluoride in the magnesium fluoride-doped silicon dioxide target is 1:1.

[0049] Experimental Example 2: Hardness, Refractive Index, and Haze Tests

[0050] The hardness of Examples 1, 6-9, and Comparative Examples 5-8 was tested according to the test method of Experimental Example 1. The refractive index of Examples 1, 6-9, and Comparative Examples 5-8 at 550 nm was measured using a spectrophotometer. The haze (%) of Examples 1, 6-9, and Comparative Examples 5-8 was measured at 25°C. The lower the haze, the better the light transmittance and the less obvious the white fog phenomenon. The results are shown in Table 4.

[0051] Table 4. Hardness, refractive index, and haze tests of Examples 1, 6-9, and Comparative Examples 5-8

[0052] Example Hardness / H Refractive index Haze at 25℃ / % Example 1 7 1.48 0.2 Example 6 6 1.59 0.4 Example 7 6 1.56 0.3 Example 8 7 1.52 0.3 Example 9 7 1.49 0.2 Comparative Example 5 8 2.32 1.5 Comparative Example 6 6 1.85 0.9 Comparative Example 7 6 1.47 0.6 Comparative Example 8 4 1.41 1.8

[0053] Table 4 shows that Comparative Example 5 only underwent initial treatment, meaning that the entire functional layer is a high-refractive-index material of zirconia-doped niobium oxide. Although its hardness reaches 8H (thanks to the high hardness of niobium oxide ceramic), its refractive index at 550 nm is as high as 2.32, which is much higher than that of the optical substrate (usually n≈1.52). This huge refractive index mismatch leads to strong Fresnel reflection at the interface between the film and the substrate, and light cannot effectively enter the interior of the film. In addition, a single high-refractive-index thick film is prone to accumulating large internal stress during the deposition process, resulting in non-uniform microstructure, which in turn causes increased light scattering, manifested as a significant increase in haze to 1.5%, and loss of anti-reflection and high light transmittance functions. Comparative Example 6 only underwent intermediate processing, resulting in a homogeneous mixed film with a refractive index of approximately 1.85. This film does not match the refractive index of the substrate or the refractive index of air, and cannot form an effective refractive index gradient transition. The resulting two abrupt interfaces (substrate / film and film / air) lead to multiple interference reflections, failing to achieve a wide-band anti-reflection effect. Compared to the gradient structure of Example 1, this single intermediate refractive index material, although having acceptable hardness (6H), suffers from greater light loss due to the lack of a guiding mechanism for the optical path, and its haze (0.9%) is significantly higher than that of Example 1. Comparative Example 7 only underwent the final stage of processing, namely, the deposition of a dense magnesium fluoride-doped silicon dioxide layer. Although its refractive index (1.47) is close to that of the substrate and its haze (0.6%) is relatively low, its hardness is only 6H, and it does not form a loose and porous surface layer structure similar to that in Example 1. More importantly, it lacks the underlying high refractive index material and the intermediate gradient transition layer. As a result, the light lacks the guidance of the optical funnel effect during the incident process, and the intrinsic reflection of the substrate surface cannot be eliminated. Consequently, the overall optical transparency and visual effect are not as good as those of Example 1, which has a complete gradient structure. Comparative Example 8 changed the ratio of magnesium fluoride-doped silica target material to silica to magnesium fluoride in a 1:1 ratio. Since the oxide and fluoride are thermodynamically immiscible, high-concentration mixing leads to severe nanophase separation. This phase separation structure will generate a large number of interfaces with abrupt changes in refractive index inside the film. Due to the severe phase separation at the 1:1 mixing ratio, the resulting grain size grows (possibly greater than 50 nm). The coarse grains not only increase internal scattering (Mie scattering) but also cause the film surface to be extremely rough, resulting in increased haze and seriously affecting the light transmittance of the material.

[0054] Examples 10-13 refer to the parameter conditions in Example 1, with specific differences shown in Table 5.

[0055] Table 5 Parameter conditions for Examples 1 and 10-13

[0056] Example Ar flow rate / sccm Surface layer thickness / nm <![CDATA[Ozone concentration / g / Nm 3 > Processing time / min Example 1 110 90 120 15 Example 10 100 80 110 10 Example 11 120 85 115 10 Example 12 100 95 125 20 Example 13 120 100 130 20

[0057] Comparative Example 9 follows the same parameters and conditions as in Example 1, except that a silicon dioxide target is used in the surface layer preparation process.

[0058] Comparative Example 10 follows the same parameters and conditions as in Example 1, except that a magnesium fluoride target is used in the surface layer preparation process.

[0059] Comparative Example 11 follows the same parameters and conditions as in Example 1, except that ozone is not introduced during the post-treatment process.

[0060] Experimental Example 3: Hardness, Refractive Index, and Haze Tests

[0061] The hardness, refractive index, and haze of Examples 1, 10-13, and Comparative Examples 9-11 were tested according to the test method of Experimental Example 2. The results are shown in Table 6. The refractive index and haze properties of Examples 1, 10-13, and Comparative Examples 9-11 are as follows: Figure 1 As shown.

[0062] Table 6 Hardness, refractive index, and haze tests of Examples 1, 10-13, and Comparative Examples 9-11

[0063] Example Hardness / H Refractive index Haze at 25℃ / % Example 1 7 1.48 0.2 Example 10 7 1.51 0.4 Example 11 6 1.53 0.3 Example 12 7 1.50 0.2 Example 13 7 1.48 0.3 Comparative Example 9 7 1.54 0.6 Comparative Example 10 4 1.39 1.5 Comparative Example 11 6 1.53 0.8

[0064] From Table 6 and Figure 1It can be observed that Comparative Example 9 used a pure silica target (without magnesium fluoride doping) in the surface layer preparation process. Although silica itself has high mechanical strength, keeping the film hardness at 7H, comparable to Example 1, it exhibits significant shortcomings in optical performance. The intrinsic refractive index of pure silica (approximately 1.46-1.48) is higher than that of the composite material doped with magnesium fluoride (which can be reduced to below 1.38). Because the refractive index of the surface layer cannot be low enough, it cannot form a good refractive index match with air, and cannot effectively construct a subwavelength anti-reflection structure. This refractive index mismatch leads to an increase in residual surface reflection, which is reflected in the test as a higher refractive index reading and a haze increase to 0.6%, with lower light transmission clarity than Example 1. Comparative Example 10 used a pure magnesium fluoride target in the surface layer preparation process. Although magnesium fluoride has an extremely low refractive index, which theoretically can bring a good anti-reflection effect, its fatal flaw is its poor mechanical properties and high crystallinity. The pure magnesium fluoride film is relatively soft and brittle, causing the overall hardness to drop sharply to 4H, which cannot meet the requirements of wear-resistant protection. In addition, pure magnesium fluoride is prone to forming large columnar crystals during the deposition process, which leads to a sharp increase in surface roughness. This rough surface causes severe light scattering (Rayleigh scattering), which causes the haze to surge to 1.5%, exhibiting an obvious "white fog" phenomenon, which seriously damages the transparency of the optical coating. Comparative Example 11 did not introduce ozone during post-processing, relying solely on thermal annealing. Test results showed a slight decrease in hardness, and its refractive index and haze were inferior to Example 1. This is because the lack of strong oxidative repair effect from high-concentration ozone meant that the trace oxygen vacancies generated during deposition could not be filled, resulting in the presence of non-stoichiometric low-valence oxides in the film. These defects became light absorption and scattering centers, leading to increased haze. Simultaneously, the lack of ozone-assisted oxidative crosslinking resulted in lower film density and stress release compared to the ozone-treated sample, thus affecting the final hardness and structural stability of the film.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-transmittance optical coating material, characterized in that, Includes the following steps: The optical substrate is subjected to surface activation and ion cleaning to obtain a pretreated substrate; A stress buffer layer is deposited on the pretreated substrate using a zirconium oxide-doped niobium oxide ceramic target; a functional layer is deposited on the surface of the stress buffer layer using a dual-target co-sputtering method; a surface layer is deposited on the surface of the functional layer using a magnesium fluoride-doped silicon dioxide target, and the optical coating material is obtained after post-treatment. The method for fabricating the functional layer is as follows: Simultaneously turn on the zirconium oxide-doped niobium oxide ceramic target and the magnesium fluoride-doped silica target. Control the power of the two cathode targets through a program. In the initial stage: the power of the zirconium oxide-doped niobium oxide ceramic target gradually decreases from 5 kW to 3-4 kW, and the power of the magnesium fluoride-doped silica target gradually increases from 0 kW to 0.6-0.8 kW over a period of 450-550 s. In the intermediate stage: the power of the zirconium oxide-doped niobium oxide ceramic target gradually decreases to 1-2 kW, and the power of the magnesium fluoride-doped silica target gradually increases from 0 kW to 0.6-0.8 kW over a period of 450-550 s. The power of the doped silicon dioxide target gradually increases to 1.5-2.5 kW over a period of 450-550 s; in the final stage, the power of the zirconium oxide-doped niobium oxide ceramic target gradually decreases to 0 kW, while the power of the magnesium fluoride-doped silicon dioxide target gradually increases to 2.5-3.5 kW over a period of 500 s; the substrate bias voltage decreases from -150 V to -50 V; the introduced gas is a mixture of Ar and O2, with the Ar flow rate constant at 40 sccm and the O2 flow rate gradually decreasing from 25 sccm to 5 sccm.

2. The method for preparing a high-transmittance optical coating material according to claim 1, characterized in that, The surface activation and ion cleaning process is as follows: the optical substrate is ultrasonically cleaned and dried, placed in a vacuum chamber and heated, argon and oxygen are introduced to perform ion cleaning on the surface of the optical substrate, and hexamethyldisilazane vapor is introduced in the final stage to obtain the pretreated substrate.

3. The method for preparing a high-transmittance optical coating material according to claim 1, characterized in that, The stress buffer layer is prepared by depositing a stress buffer layer with a thickness of 13-17 nm on the surface of the pretreated substrate using the zirconia-doped niobium oxide ceramic target; the introduced gas is a mixture of argon and oxygen; the zirconia-doped niobium oxide ceramic target is prepared by sintering niobium oxide and zirconia.

4. The method for preparing a high-transmittance optical coating material according to claim 1, characterized in that, The functional layer has a deposition thickness of 440-460 nm; the magnesium fluoride-doped silicon dioxide target is prepared by sintering silicon dioxide and magnesium fluoride.

5. The method for preparing a high-transmittance optical coating material according to claim 1, characterized in that, The surface layer is prepared by RF magnetron sputtering, with only the magnesium fluoride-doped silicon dioxide target turned on, a mixture of argon and oxygen gas introduced, and the substrate bias turned off, to deposit a surface layer with a thickness of 80-100 nm on the surface of the functional layer.

6. The method for preparing a high-transmittance optical coating material according to claim 1, characterized in that, The specific post-processing procedure is as follows: stop sputtering, maintain vacuum, turn on the heater, introduce ozone treatment, and cool out of the cavity to obtain the optical coating material.

7. A high-transmittance optical coating material, characterized in that, The optical coating material includes a stress buffer layer, a functional layer, and a surface layer; the optical coating material is prepared by the preparation method according to any one of claims 1-6.

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