A solar blind ultraviolet filter structure and a preparation method thereof

Abstract

The application belongs to the technical field of optical film manufacturing, and specifically discloses a solar blind ultraviolet filter structure and a preparation method thereof. In the application, the alternating HfO2 layers and SiO2 layers in the inner antireflection matching layer improve the transmittance in the 200nm-300nm wave band; the first Al layer and the second Al layer in the metal-induced layer effectively reflect light in the wave band above 300nm, and reduce the transmittance thereof; and the outer antireflection matching layer is designed through multiple SiO2 and HfO2 layers, further optimizes the transmittance in the 200nm-300nm wave band, and inhibits the light in the 300nm-900nm wave band from passing through, thereby ensuring the high spectral stability. The solar blind ultraviolet filter structure provided by the application not only can improve the spectral stability, but also can ensure the high transmittance in the 200nm-300nm wave band, reduce the light transmittance in the 300nm-900nm wave band, and meet the precise control requirement of the solar blind ultraviolet filter on the spectrum.

Description

Technical Field

[0001] This invention belongs to the field of optical thin film manufacturing technology, and specifically relates to a solar-blind ultraviolet filter structure and its preparation method. Background Technology

[0002] Currently, there are two main approaches to achieving high-performance solar-blind ultraviolet (UV) filters: interferometry and absorption. Interferometric filters (made of alternating layers of high- and low-refractive-index dielectric films or metal films and dielectric films) are widely studied by domestic research institutions due to their strong environmental adaptability and flexible control methods. For example, researchers have disclosed a fully dielectric solar-blind UV filter composed of three substrates, eliminating the need for one or more polymer materials; the addition of a reflection suppression layer effectively reduces the reflectivity of the induced transmission filter in the visible light region; the overall thickness can be relatively thin, ranging from 0.6 mm to 5 mm. Other researchers have proposed a design and fabrication method for a dual-cavity UV bandpass filter based on a FP structure, where film thickness monitoring combines optical and temporal control. Through sensitivity analysis of the film structure and accurate control of the sensitive spacer layer, high transmittance in the 200 nm–400 nm wavelength range can be achieved. However, the design and fabrication of interferometric filters, especially induced transmission filters composed of metal and dielectric films, present significant challenges. Addressing the challenge of designing and matching existing solar-blind ultraviolet filters, providing a solar-blind ultraviolet filter structure and its fabrication method is of great significance. Summary of the Invention

[0003] Therefore, embodiments of the present invention provide a solar-blind ultraviolet filter structure and its fabrication method. In this invention, the alternating HfO2 and SiO2 layers in the inner antireflection matching layer improve the transmittance in the 200nm-300nm wavelength band; the first Al and second Al layers in the metal-induced layer effectively reflect light above 300nm, reducing its transmittance; the outer antireflection matching layer, through the design of multiple SiO2 and HfO2 layers, further optimizes the transmittance in the 200nm-300nm wavelength band and suppresses the transmission of light in the 300nm-900nm wavelength band, ensuring high spectral stability. The solar-blind ultraviolet filter structure provided by this invention not only improves spectral stability but also ensures high transmittance in the 200nm-300nm wavelength band and reduces light transmission in the 300nm-900nm wavelength band, meeting the precise spectral control requirements of solar-blind ultraviolet filters.

[0004] The first aspect of the present invention provides a solar-blind ultraviolet filter structure, which sequentially includes a substrate, an inner anti-reflection matching layer, a metal induction layer and an outer anti-reflection matching layer; Wherein, the substrate is a ZWB substrate; The internal antireflection matching layer includes a first HfO2 layer and a first SiO2 layer sequentially deposited on the substrate; The metal-inducing layer comprises a first Al layer, a second SiO2 layer, and a second Al layer sequentially deposited on the inner antireflection matching layer; The external antireflection matching layer comprises SiO2 layers and HfO2 layers deposited alternately on the metal-induced layer in sequence.

[0005] Compared to existing technologies, the solar-blind ultraviolet filter structure provided by this invention incorporates a ZWB substrate, which can regulate the cutoff level of the filter for visible and far-infrared light, reducing the transmittance of visible and far-infrared light. This invention defines the internal antireflection matching layer as comprising a first HfO2 layer and a first SiO2 layer. Due to the significant difference in refractive indices between the two materials, their deposition on the substrate can form an optical interference effect, effectively improving the transmittance of light in the 200nm-300nm wavelength range of ultraviolet light. In the metal-inducing layer, the Al layers in the first and second Al layers work together to have a more significant impact on the propagation and absorption of light, effectively absorbing and blocking light in the 300nm-900nm wavelength range, thus improving the transmittance of light in the 200nm-300nm wavelength range. The second SiO2 layer further enhances this effect. The first step adjusts the optical properties of the metal-induced layer, enhancing the filtering effect above 300nm by regulating light propagation. Simultaneously, the second SiO2 layer helps reduce light scattering, improving light transmittance in the 200nm-300nm band. In the external anti-reflection matching layer, the low refractive index of the SiO2 layer helps reduce light reflection and increase transmittance, while the HfO2 layer improves light transmittance in the 200nm-300nm band. By alternating the deposition of multiple SiO2 and HfO2 layers, the transmittance in the 300nm-900nm band can be significantly reduced, while the transmittance in the 200nm-300nm band can be increased. Furthermore, the multi-layered external anti-reflection matching layer also reduces light scattering and loss during propagation, improving the optical accuracy and stability of the solar-blind ultraviolet filter.

[0006] In this invention, the alternating HfO2 and SiO2 layers in the inner antireflection matching layer improve the transmittance in the 200nm-300nm wavelength range; the first and second Al layers in the metal-induced layer effectively reflect light above 300nm, reducing its transmittance; the outer antireflection matching layer, through the design of multiple SiO2 and HfO2 layers, further optimizes the transmittance in the 200nm-300nm wavelength range and suppresses the transmission of light in the 300nm-900nm wavelength range, ensuring high spectral stability. The solar-blind ultraviolet filter structure provided by this invention not only improves spectral stability but also ensures high transmittance in the 200nm-300nm wavelength range and reduces light transmission in the 300nm-900nm wavelength range, meeting the precise spectral control requirements of solar-blind ultraviolet filters.

[0007] In a preferred embodiment, the internal antireflection matching layer is deposited starting on the first SiO2 layer of the metal-induced layer.

[0008] In a preferred embodiment, the external antireflection matching layer is deposited on the second Al layer of the internal antireflection matching layer.

[0009] Preferably, the alternating SiO2 and HfO2 layers comprise four SiO2 layers and three HfO2 layers.

[0010] More preferably, the alternately deposited SiO2 layers and HfO2 layers include the following arrangement: a third SiO2 layer, a second HfO2 layer, a fourth SiO2 layer, a third HfO2 layer, a fifth SiO2 layer, a fourth HfO2 layer, and a sixth SiO2 layer.

[0011] This invention, by further defining the structure of the external antireflection matching layer, is beneficial to further improving the optical accuracy and stability of solar-blind ultraviolet filters.

[0012] Preferably, the substrate is a ZWB3 substrate.

[0013] Preferably, the thickness of the ZWB substrate is 1 nm to 10 nm.

[0014] Preferably, the thickness of the first HfO2 layer is 96.24 nm to 102.24 nm.

[0015] Preferably, the thickness of the first SiO2 layer is 165.92 nm to 175.92 nm.

[0016] Preferably, the thickness of the first Al layer is 14.5 nm to 15.5 nm.

[0017] Preferably, the thickness of the second SiO2 layer is 64.65 nm to 68.65 nm.

[0018] Preferably, the thickness of the second Al layer is 14.5 nm to 15.5 nm.

[0019] Preferably, the thickness of the third SiO2 layer is 81.98 nm to 85.98 nm.

[0020] Preferably, the thickness of the second HfO2 layer is 31.99 nm to 33.99 nm.

[0021] Preferably, the thickness of the fourth SiO2 layer is 43.59 nm to 45.59 nm.

[0022] Preferably, the thickness of the third HfO2 layer is 31.87 nm to 33.87 nm.

[0023] Preferably, the thickness of the fifth SiO2 layer is 43.31 nm to 45.31 nm.

[0024] Preferably, the thickness of the fourth HfO2 layer is 31.42 nm to 33.42 nm.

[0025] Preferably, the thickness of the sixth SiO2 layer is 139.74 nm to 145.74 nm.

[0026] By further limiting the thickness of each film layer, this invention can further improve the spectral stability of the solar-blind ultraviolet filter while ensuring high transmittance in the 200nm~300nm wavelength range.

[0027] A second aspect of the present invention provides a method for preparing the above-mentioned solar-blind ultraviolet filter structure, comprising the following steps: S1. Determine the thickness of the substrate and each film layer in the inner antireflection matching layer, the metal induction layer and the outer antireflection matching layer based on the target transmission spectrum curve. S2, with a vacuum degree ≤ 5 × 10 -4 An inner anti-reflection matching layer was deposited on the ZWB substrate at Pa and 195℃~205℃ using a physical vapor deposition method. S3, with a vacuum degree ≤ 8×10 -5 At 50℃~100℃, a metal-inducing layer and an outer anti-reflection matching layer are sequentially deposited on the inner anti-reflection matching layer by physical vapor deposition to obtain a primary solar-blind ultraviolet filter. S4. The primary solar-blind ultraviolet filter is aged at 30℃~70℃. The transmission spectrum curve after aging is tested, and the transmission spectrum curve after aging is fitted and inverted to determine the thickness of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer and the third SiO2 layer after aging, thus obtaining the aged solar-blind ultraviolet filter. S5. Based on the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer in the aged solar-blind ultraviolet filter, and the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer determined in S1 based on the target transmission spectrum curve, the correction ratio factors are determined to be X1~X5 respectively. S6. Determine the thickness of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer before aging based on the correction scaling factor. Repeat S2 to S5 to optimize until the test transmission spectrum curve is consistent with the target transmission spectrum curve. That is, the solar-blind ultraviolet filter structure obtained in the last aging process is the solar-blind ultraviolet filter structure.

[0028] During their research, the inventors discovered that existing solar-blind ultraviolet (UV) filters typically require a combination of metal and dielectric films to form an induced transmission filter. However, due to oxidation and dispersion of the metal and dielectric materials, the actual results of existing solar-blind UV filters often deviate significantly from the design results. Furthermore, the fabricated solar-blind UV filters are inevitably affected by changes in external temperature and humidity, causing their spectra to change and deviate from the optimal transmission spectrum curve. This results in problems such as large fabrication errors and spectral instability in existing solar-blind UV filters. Therefore, there is an urgent need to propose a method for fabricating a solar-blind UV filter structure.

[0029] Compared to existing technologies, the method for fabricating a solar-blind ultraviolet filter structure provided by this invention allows for the determination of the thickness of each film layer in the inner antireflection matching layer, the metal induction layer, and the outer antireflection matching layer based on the target transmission spectrum curve. The deposition temperature of the inner antireflection matching layer is limited to 195℃~205℃, and the deposition temperatures of the metal induction layer and the outer antireflection matching layer are limited to 50℃~100℃. The inventors creatively introduce a variable-temperature physical vapor deposition method under vacuum conditions. By avoiding the influence of oxidation and contamination on the metal oxide layers and Al layers in the prepared inner antireflection matching layer, metal induction layer, and outer antireflection matching layer, the performance of the Al layer and other metal oxide layers is greatly improved. This effectively achieves the matching between ultraviolet filter films, reduces the fabrication difficulty of solar-blind ultraviolet filters, reduces fabrication errors, and avoids spectral instability problems. This invention creatively introduces an accelerated aging process. By simulating actual usage environments, it determines that the performance of the aged film layer has reached stability and tests the transmission spectrum curve after aging. Furthermore, by fitting and inverting the transmission spectrum curve after aging, the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer after aging can be determined. Then, based on the correction scaling factor, the thickness design before aging is reversed. The deposition and aging tests are repeated until the tested transmission spectrum curve matches the target transmission spectrum curve. This invention gradually reduces the difference between the actual prepared solar-blind ultraviolet filter transmission spectrum curve and the target transmission spectrum curve through iterative optimization, thereby improving spectral stability, reducing errors generated during preparation, and achieving precise preparation of the solar-blind ultraviolet filter structure.

[0030] It should be further explained that the method for determining the target transmission spectrum curve is as follows: HfO2 thin film, SiO2 thin film and Al thin film are prepared by electronic evaporation, and the refractive index, thickness and scaling factor of each film are calibrated. The target parameters, including the wavelength and transmittance, are set and optimized according to the technical requirements of the solar-blind ultraviolet filter.

[0031] Preferably, in S2, the conditions for deposition of the first HfO2 layer in the inner antireflection matching layer are: electron beam current of 130mA~500mA, evaporation rate of 2Å / s~5Å / s, ion source beam current of 50A~100A, ion source beam voltage of 100V~400V, and ion source oxygen flux of 10sccm~20sccm.

[0032] Preferably, in S2, the conditions for deposition of the first SiO2 layer in the internal antireflection matching layer are: electron beam current of 40mA~80mA, evaporation rate of 3Å / s~5Å / s, and oxygen flux of ion source of 10sccm~30sccm.

[0033] Preferably, in S3, the deposition conditions of the first Al layer and the second Al layer in the metal-induced layer are both: electron beam current of 20mA~100mA and evaporation rate of 10Å / s~20Å / s.

[0034] Preferably, in S3, the conditions for deposition of the second SiO2 layer in the metal-induced layer are: electron beam current of 40mA~80mA, evaporation rate of 3Å / s~5Å / s, and oxygen flux of ion source of 10sccm~30sccm.

[0035] Preferably, in S3, the deposition conditions for the third, fourth, fifth, and sixth SiO2 layers in the external antireflection matching layer are: electron beam current of 40mA~80mA, evaporation rate of 3Å / s~5Å / s, and oxygen flux of ion source of 10sccm~30sccm.

[0036] Preferably, in S3, the deposition conditions for the second, third, and fourth HfO2 layers in the external antireflection matching layer are as follows: electron beam current of 130mA~500mA, evaporation rate of 2Å / s~5Å / s, ion source beam current of 50A~100A, ion source beam voltage of 100V~400V, and ion source oxygen flux of 10sccm~20sccm.

[0037] Optimal deposition conditions can improve the performance of the Al layer and other metal oxide layers, effectively achieve the matching between ultraviolet filter films, and thus improve the spectral stability of solar-blind ultraviolet filters.

[0038] Preferably, in step S4, the aging treatment time is 4 to 8 hours.

[0039] It should be further explained that in S5 and S6, the correction ratio factor = thickness of the film after aging / thickness of the film before aging. Attached Figure Description

[0040] Figure 1The transmission spectrum curve of the solar-blind ultraviolet filter structure prepared in Example 1 of the present invention is shown. Figure 2 This is a transmission spectrum curve of the solar-blind ultraviolet filter structure prepared in Example 2 of the present invention; Figure 3 The transmission spectrum curve of the solar-blind ultraviolet filter structure prepared in Example 3 of the present invention is shown. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] Example 1 This embodiment provides a solar-blind ultraviolet filter structure, which sequentially includes a substrate, an inner anti-reflection matching layer, a metal induction layer, and an outer anti-reflection matching layer, as detailed below: This embodiment also provides a method for preparing the above-mentioned solar-blind ultraviolet filter structure, including the following steps: S1. The method for determining the target transmission spectrum curve is as follows: HfO2 film, SiO2 film and Al film are prepared by electronic evaporation. The refractive index, thickness and scale factor of each film are calibrated. The target parameters, including the wavelength and transmittance, are set and optimized according to the technical requirements of the solar-blind ultraviolet filter. Based on the target transmission spectrum curves, the composition and thickness of each film layer in the substrate, inner antireflection matching layer, metal-induced layer, and outer antireflection matching layer were determined, as shown in Table 1. The target transmission spectrum curves are shown in [Figure 1]. Figure 1 ; Table 1 S2, with a vacuum degree ≤ 5 × 10 -4 An internal antireflection matching layer was deposited on the ZWB3 substrate at Pa and 200℃ using physical vapor deposition. The deposition conditions for the first HfO2 layer were: electron beam current of 130 mA, evaporation rate of 2 Å / s, ion source current of 50 A, ion source voltage of 400 V, and ion source oxygen flux of 10 sccm. The deposition conditions for the first SiO2 layer were: electron beam current of 40 mA, evaporation rate of 3 Å / s, and ion beam oxygen flux of 10 sccm. S3, with a vacuum degree ≤ 8×10 -5At 50°C and 50°C, a metal-induced layer and an outer antireflection matching layer were sequentially deposited on the inner antireflection matching layer using physical vapor deposition to obtain a primary solar-blind ultraviolet filter. The deposition conditions for the first and second Al layers were: electron beam current 20 mA and evaporation rate 10 Å / s; the deposition conditions for the second SiO2 layer were: electron beam current 40 mA, evaporation rate 5 Å / s, and ion beam oxygen flux 10 sccm; the third SiO2 layer… The deposition conditions for the first, second, third, and sixth SiO2 layers were: electron beam current of 40 mA, evaporation rate of 5 Å / s, and oxygen flux of ion beam of 10 sccm. The deposition conditions for the third, fourth, and fifth HfO2 layers were: electron beam current of 130 mA, evaporation rate of 2 Å / s, ion source current of 50 A, ion source beam voltage of 400 V, and oxygen flux of ion beam of 20 sccm. S4. At 30°C, the primary solar-blind ultraviolet filter is aged for 4 hours. The transmission spectrum curve after aging is tested, and the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer are determined to obtain the aged solar-blind ultraviolet filter. S5. Based on the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer in the aged solar-blind ultraviolet filter, the correction factors are determined to be X1~X5 respectively. S6. Determine the thickness of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer before aging according to the correction factor. Repeat S2~S5 to optimize until the test transmission spectrum curve is consistent with the target transmission spectrum curve. That is, the solar-blind ultraviolet filter structure obtained in the last aging is the solar-blind ultraviolet filter structure.

[0043] Example 2 This embodiment provides a solar-blind ultraviolet filter structure, which sequentially includes a substrate, an inner anti-reflection matching layer, a metal induction layer, and an outer anti-reflection matching layer, as detailed below: This embodiment also provides a method for preparing the above-mentioned solar-blind ultraviolet filter structure, including the following steps: S1. The method for determining the target transmission spectrum curve is as follows: HfO2 film, SiO2 film and Al film are prepared by electronic evaporation. The refractive index, thickness and scale factor of each film are calibrated. The target parameters, including the wavelength and transmittance, are set and optimized according to the technical requirements of the solar-blind ultraviolet filter. Based on the target transmission spectrum curves, the composition and thickness of each film layer in the substrate, inner antireflection matching layer, metal-induced layer, and outer antireflection matching layer were determined, as shown in Table 2. The target transmission spectrum curves are shown in [Figure 1]. Figure 2 ; Table 2 S2, with a vacuum degree ≤ 5 × 10 -4 An internal antireflection matching layer was deposited on the ZWB3 substrate at Pa and 205℃ using physical vapor deposition. The deposition conditions for the first HfO2 layer were: electron beam current of 500 mA, evaporation rate of 5 Å / s, ion source current of 100 A, ion source voltage of 100 V, and ion source oxygen flux of 20 sccm. The deposition conditions for the first SiO2 layer were: electron beam current of 80 mA, evaporation rate of 5 Å / s, and ion beam oxygen flux of 30 sccm. S3, with a vacuum degree ≤ 8×10 -5 At 100°C and 100 Pa, a metal-induced layer and an outer antireflection matching layer were sequentially deposited on the inner antireflection matching layer using physical vapor deposition to obtain a primary solar-blind ultraviolet filter. The deposition conditions for the first and second Al layers were: electron beam current of 100 mA and evaporation rate of 20 Å / s; the deposition conditions for the second SiO2 layer were: electron beam current of 80 mA, evaporation rate of 3 Å / s, and ion beam oxygen flux of 30 sccm; the third SiO2 layer… The deposition conditions for the first, fourth, fifth, and sixth SiO2 layers were: electron beam current of 80 mA, evaporation rate of 3 Å / s, and oxygen flux of ion beam of 30 sccm. The deposition conditions for the second, third, and fourth HfO2 layers were: electron beam current of 500 mA, evaporation rate of 5 Å / s, ion source current of 100 A, ion source beam voltage of 100 V, and oxygen flux of ion beam of 10 sccm. S4. The primary solar-blind ultraviolet filter is aged at 70°C for 8 hours. The transmission spectrum curve after aging is tested, and the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer are determined to obtain the aged solar-blind ultraviolet filter. S5. Based on the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer in the aged solar-blind ultraviolet filter, the correction factors are determined to be X1~X5 respectively. S6. Determine the thickness of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer before aging according to the correction factor. Repeat S2~S5 to optimize until the test transmission spectrum curve is consistent with the target transmission spectrum curve. That is, the solar-blind ultraviolet filter structure obtained in the last aging is the solar-blind ultraviolet filter structure.

[0044] Example 3 This embodiment provides a solar-blind ultraviolet filter structure, which sequentially includes a substrate, an inner anti-reflection matching layer, a metal induction layer, and an outer anti-reflection matching layer, as detailed below: This embodiment also provides a method for preparing the above-mentioned solar-blind ultraviolet filter structure, including the following steps: S1. The method for determining the target transmission spectrum curve is as follows: HfO2 film, SiO2 film and Al film are prepared by electronic evaporation. The refractive index, thickness and scale factor of each film are calibrated. The target parameters, including the wavelength and transmittance, are set and optimized according to the technical requirements of the solar-blind ultraviolet filter. The composition and thickness of each film layer in the substrate, inner antireflection matching layer, metal-induced layer, and outer antireflection matching layer were determined based on the target transmission spectrum curves, as shown in Table 3. The target transmission spectrum curves are shown in [Figure 1]. Figure 3 ; Table 3 S2, with a vacuum degree ≤ 5 × 10 -4 An internal antireflection matching layer was deposited on the ZWB3 substrate at 195°C using physical vapor deposition. The deposition conditions for the first HfO2 layer were: electron beam current of 300 mA, evaporation rate of 4 Å / s, ion source current of 60 A, ion source voltage of 300 V, and ion source oxygen flux of 15 sccm. The deposition conditions for the first SiO2 layer were: electron beam current of 60 mA, evaporation rate of 4 Å / s, and ion beam oxygen flux of 20 sccm. S3, with a vacuum degree ≤ 8×10 -5 At 60°C and 60 Pa, a metal-induced layer and an outer antireflection matching layer were sequentially deposited on the inner antireflection matching layer using physical vapor deposition to obtain a primary solar-blind ultraviolet filter. The deposition conditions for the first and second Al layers were: electron beam current 60 mA and evaporation rate 15 Å / s; the deposition conditions for the second SiO2 layer were: electron beam current 60 mA, evaporation rate 4 Å / s, and ion beam oxygen flux 20 sccm; the third SiO2 layer… The deposition conditions for the first, second, third, and fourth SiO2 layers were as follows: electron beam current of 60 mA, evaporation rate of 4 Å / s, and oxygen flux of ion beam of 20 sccm. The deposition conditions for the third, fourth, and fifth HfO2 layers were as follows: electron beam current of 300 mA, evaporation rate of 3 Å / s, ion source current of 70 A, ion source voltage of 200 V, and oxygen flux of ion beam of 15 sccm. S4. The primary solar-blind ultraviolet filter is aged at 40°C for 6 hours. The transmission spectrum curve after aging is tested, and the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer are determined to obtain the aged solar-blind ultraviolet filter. S5. Based on the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer in the aged solar-blind ultraviolet filter, the correction factors are determined to be X1~X5 respectively. S6. Determine the thickness of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer before aging according to the correction factor. Repeat S2~S5 to optimize until the test transmission spectrum curve is consistent with the target transmission spectrum curve. That is, the solar-blind ultraviolet filter structure obtained in the last aging is the solar-blind ultraviolet filter structure.

[0045] Comparative Example 1 This comparative example provides a method for preparing a solar-blind ultraviolet filter structure. The method differs from the example in that, in S3, the temperature at which the metal-inducing layer and the outer anti-reflection matching layer are deposited sequentially on the inner anti-reflection matching layer by physical vapor deposition is 200°C. The structure and other steps of the other solar-blind ultraviolet filters are the same as in Example 1.

[0046] The solar-blind ultraviolet filters prepared in Example 1 and Comparative Example 1 were placed at room temperature, and their average transmittance in the ultraviolet wavelength range of 260nm~275nm was measured one week, one month, and three months after preparation. The details are shown in Table 4. As can be seen from Table 1, the transmittance of the solar-blind ultraviolet filter prepared in Example 1 of the present invention did not change significantly after being placed for 3 months compared with that at day 0, which indicates that the solar-blind ultraviolet filter prepared in Example 1 of the present invention has better spectral stability; while in Comparative Example 1, due to the high temperature effect of the external antireflection matching layer, the ultraviolet transmittance was already at a low level at day 0, and the transmittance decreased significantly with the increase of the placement time, and only tended to stabilize after 1 month.

[0047] Both Embodiment 2 and Embodiment 3 of the present invention can achieve technical effects comparable to those of Embodiment 1.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a solar-blind ultraviolet filter structure, characterized in that, Includes the following steps: S1. Determine the thickness of the substrate and each film layer in the inner antireflection matching layer, the metal induction layer and the outer antireflection matching layer based on the target transmission spectrum curve. S2, with a vacuum degree ≤ 5 × 10 -4 An inner anti-reflection matching layer was deposited on a ZWB substrate at Pa and 195℃~205℃ using a physical vapor deposition method. S3, with a vacuum degree ≤ 8×10 -5 At 50℃~100℃, a metal-inducing layer and an outer anti-reflection matching layer are sequentially deposited on the inner anti-reflection matching layer by physical vapor deposition to obtain a primary solar-blind ultraviolet filter. S4. The primary solar-blind ultraviolet filter is aged at 30℃~70℃. The transmission spectrum curve after aging is tested, and the transmission spectrum curve after aging is fitted and inverted to determine the thickness of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer and the third SiO2 layer after aging, thus obtaining the aged solar-blind ultraviolet filter. S5. Based on the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer in the aged solar-blind ultraviolet filter, and the thicknesses of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer determined in S1 based on the target transmission spectrum curve, the correction ratio factors are determined to be X1~X5 respectively. S6. Determine the thickness of the first SiO2 layer, the first Al layer, the second SiO2 layer, the second Al layer, and the third SiO2 layer before aging according to the correction ratio factor. Repeat S2~S5 and optimize until the test transmission spectrum curve is consistent with the target transmission spectrum curve. That is, the solar blind ultraviolet filter structure obtained in the last aging is the solar blind ultraviolet filter structure. The internal antireflection matching layer includes a first HfO2 layer and a first SiO2 layer sequentially deposited on the substrate; The metal-inducing layer comprises a first Al layer, a second SiO2 layer, and a second Al layer sequentially deposited on the inner antireflection matching layer; The external antireflection matching layer comprises SiO2 layers and HfO2 layers deposited alternately on the metal-induced layer in sequence.

2. The method for preparing the solar-blind ultraviolet filter structure as described in claim 1, characterized in that, In S2, the deposition conditions of the first HfO2 layer in the internal antireflection matching layer are as follows: electron beam current of 130mA~500mA, evaporation rate of 2Å / s~5Å / s, ion source beam current of 50A~100A, ion source beam voltage of 100V~400V, and ion source oxygen flux of 10sccm~20sccm; and / or In S2, the conditions for deposition of the first SiO2 layer in the inner antireflection matching layer are: electron beam current of 40mA~80mA, evaporation rate of 3Å / s~5Å / s, and oxygen flux of ion source of 10sccm~30sccm.

3. The method for preparing the solar-blind ultraviolet filter structure as described in claim 1, characterized in that, In S3, the deposition conditions for the first Al layer and the second Al layer in the metal-induced layer are both: electron beam current of 20mA~100mA, evaporation rate of 10Å / s~20Å / s; and / or In S3, the conditions for deposition of the second SiO2 layer in the metal-induced layer are: electron beam current of 40mA~80mA, evaporation rate of 3Å / s~5Å / s, and oxygen flux of ion source of 10sccm~30sccm.

4. The method for preparing the solar-blind ultraviolet filter structure as described in claim 1, characterized in that, In S3, the deposition conditions for the third, fourth, fifth, and sixth SiO2 layers in the external antireflection matching layer are as follows: electron beam current of 40 mA to 80 mA, evaporation rate of 3 Å / s to 5 Å / s, and oxygen flux of the ion source of 10 sccm to 30 sccm; and / or In S3, the deposition conditions for the second, third, and fourth HfO2 layers in the external antireflection matching layer are as follows: electron beam current of 130mA~500mA, evaporation rate of 2Å / s~5Å / s, ion source beam current of 50A~100A, ion source beam voltage of 100V~400V, and ion source oxygen flux of 10sccm~20sccm; and / or In S4, the aging process takes 4 to 8 hours.

5. A solar-blind ultraviolet filter structure prepared by the method for preparing a solar-blind ultraviolet filter structure according to any one of claims 1 to 4, characterized in that, It consists of, in sequence, a substrate, an inner antireflection matching layer, a metal induction layer, and an outer antireflection matching layer.

6. The solar-blind ultraviolet filter structure as described in claim 5, characterized in that, The substrate is a ZWB3 substrate.

7. The solar-blind ultraviolet filter structure as described in claim 5, characterized in that, The alternating SiO2 and HfO2 layers consist of four SiO2 layers and three HfO2 layers.

8. The solar-blind ultraviolet filter structure as described in claim 7, characterized in that, The alternating SiO2 and HfO2 layers include the following arrangement: a third SiO2 layer, a second HfO2 layer, a fourth SiO2 layer, a third HfO2 layer, a fifth SiO2 layer, a fourth HfO2 layer, and a sixth SiO2 layer.

9. The solar-blind ultraviolet filter structure as described in claim 5 or 6, characterized in that, The thickness of the ZWB substrate is 1 nm to 10 nm; and / or The thickness of the first HfO2 layer is 96.24 nm to 102.24 nm; and / or The thickness of the first SiO2 layer is 165.92 nm to 175.92 nm; and / or The thickness of the first Al layer is 14.5 nm to 15.5 nm; and / or The thickness of the second SiO2 layer is 64.65 nm to 68.65 nm; and / or The thickness of the second Al layer is 14.5 nm to 15.5 nm.

10. The solar-blind ultraviolet filter structure as described in claim 8, characterized in that, The thickness of the third SiO2 layer is 81.98 nm to 85.98 nm; and / or The thickness of the second HfO2 layer is 31.99 nm to 33.99 nm; and / or The thickness of the fourth SiO2 layer is 43.59 nm to 45.59 nm; and / or The thickness of the third HfO2 layer is 31.87 nm to 33.87 nm; and / or The thickness of the fifth SiO2 layer is 43.31 nm to 45.31 nm; and / or The thickness of the fourth HfO2 layer is 31.42 nm to 33.42 nm; and / or The thickness of the sixth SiO2 layer is 139.74 nm to 145.74 nm.

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