Design method and preparation method of chalcogenide glass substrate 7-14 [mu] m efficient antireflection film

Abstract

The invention provides a design method and a preparation method of a chalcogenide glass substrate 7-14 [mu] m efficient antireflection film. The design method comprises the following steps: selecting 11 [mu] m as a reference wavelength for designing the film thickness of a 1 / 4 wavelength film layer of an optical thin film, and using a film stack expression Sub / 0.1 H / M / 0.6 L / 0.15 W / AIR, wherein Sub is a chalcogenide glass substrate, AIR represents air, H represents Ge, L represents YbF3, M represents ZnSe, and W represents ZnS; the method comprises the following steps: performing film thickness optimization of a single film layer on a Sub / Ge / ZnSe / YbF3 / ZnS / AIR four-layer film system structure generated by an input film stack formula through design software to obtain a preliminary film thickness, then optimizing the antireflection rate of a wave band of 12-14 microns, and determining the optimal film thickness of a front film system; finally, the reflectivity at the position of 7 microns is optimized, the film thickness of the optimal film layer of the reverse film system is determined, and based on the determined front film system and the determined reverse film system, the transmittance of the long-wave infrared band of 7-14 microns meets the requirement. And inputting the determined film thicknesses of the optimal film layers of the front surface film system and the back surface film system into a control computer of the film plating machine.

Description

Technical Field

[0001] The present disclosure relates to the technical field of infrared coating, and more particularly to a design method and a preparation method for a 7-14μm high-efficiency antireflection film on a chalcogenide glass substrate. Background Art

[0002] In the field of infrared optics, the 7-14μm long-wave infrared band has unique thermal effects closely related to the thermal radiation characteristics of many substances, and can be emitted and absorbed by most objects. Therefore, the 7-14μm long-wave infrared band is widely used in fields such as thermal imaging and temperature detection. The chalcogenide glass, an infrared optical material, has a high cost performance and good transmittance in the long-wave infrared, and can meet the requirements of materials for infrared thermal imaging systems, infrared detectors, etc. It is used to manufacture optical components such as infrared lenses and windows to help achieve infrared imaging and detection. Since it is a glass substance formed by chemical combination and is an amorphous semiconductor material, its surface chemical properties are complex, the bonding force with the coating material is weak, and the thermal expansion coefficient is quite different from that of common coating materials. These reasons make the coating process of the chalcogenide glass substrate complex and difficult. In addition, there is absorption in the chalcogenide glass after 12μm, which limits the application of the chalcogenide glass in the 7-14μm long-wave infrared band. How to design and prepare a 7-14μm high-efficiency antireflection film on a chalcogenide glass substrate has become an urgent problem to be solved in the field of optical thin films. Summary of the Invention

[0003] In view of the problems existing in the background art, an object of the present disclosure is to provide a design method and a preparation method for a 7-14μm high-efficiency antireflection film on a chalcogenide glass substrate, which can make the transmittance of the designed and prepared chalcogenide glass substrate together with the front film system and the back film system on both sides meet the requirements in the range of 7-14μm.

[0004] Another object of the present disclosure is to provide a design method and a preparation method for a 7-14μm high-efficiency antireflection film on a chalcogenide glass substrate, which can meet the requirements of strength and environmental adaptability.

[0005] Accordingly, a design method for a 7-14μm high-efficiency antireflection film on a chalcogenide glass substrate includes the steps: Sa, selecting 11μm as the reference wavelength for the film thickness of the 1 / 4 wavelength film layer in the optical thin film design, and using the film stack expression: Sub / 0.1H / M / 0.6L / 0.15W / AIR. The front and back of Sub are coated with the same film system with the same film layer sequence of the same film material. Here, Sub is the chalcogenide glass substrate, AIR represents air, H represents the high refractive index material Ge (germanium) with a 1 / 4 wavelength thickness, and L represents the low refractive index material YbF 3Ytterbium fluoride, M represents the intermediate refractive index material ZnSe (zinc selenide) with a thickness of 1 / 4 wavelength, W represents the intermediate refractive index material ZnS (zinc sulfide) with a thickness of 1 / 4 wavelength; Sb, the film thickness of the single-sided film layer of the four-layer film system structure of Sub / Ge / ZnSe / YbF 3 / ZnS / AIR was optimized, and the initial film thickness of the film layer was obtained. Then, based on the initial film thickness of the film layer, the antireflection rate in the 12 - 14 μm band was optimized to determine the optimal film thickness of the front film system. Finally, based on the optimal film thickness of the front film system, the reflectivity at 7 μm was optimized to determine the optimal film thickness of the back film system. Based on the determined front film system and back film system, the transmittance of the chalcogenide glass substrate in the 7 - 14 μm long-wave infrared band meets the requirements; Sc, the optimal film thickness of the determined front film system and back film system was input into the control computer of the coating machine.

[0006] A preparation method for a 7 - 14 μm high-efficiency antireflection film on a chalcogenide glass substrate includes the steps: S1, configuring the film system process parameters of the coating machine and preparing four film materials, namely Ge, ZnSe, ZnS, and YbF 3 . The configuration of the film system process parameters includes the background vacuum degree, temperature, optimal film thickness of the film layer, evaporation mode of the film material, deposition rate of the film material, and the use of ion source-assisted deposition. Among them, the film thickness in the film system process parameters is based on the optimal film thickness stored in the control computer of the coating machine according to the design method of the 7 - 14 μm high-efficiency antireflection film on the chalcogenide glass substrate; S2, cleaning the accompanying coating piece and the product of the chalcogenide glass substrate used as a lens before plating; S3, putting the cleaned lens into the tooling fixture, hanging the tooling fixture with the lens placed in it into the cavity of the coating machine, and slowly heating and baking under vacuum; S4, pre-melting all film materials to release gas and remove impurities and keep them at a constant temperature; S5, cleaning the lens with the ion source; S6, depositing and monitoring the film layer, depositing the film layer on the front side of the lens according to the film system parameter configuration in step S1; S7, keeping the temperature constant after plating; S8, cooling down and taking out the parts; S9, repeating steps S1 to S8 to deposit the film layer on the back side of the lens.

[0007] The beneficial effects of the present disclosure are as follows.

[0008] In the design method of a highly efficient antireflection film for a chalcogenide glass substrate in the 7 - 14 μm range according to the present disclosure, due to the large absorption of chalcogenide glass after 12 μm and the low transmittance in the 12 - 14 μm range, which leads to a low overall infrared transmission energy in the 7 - 14 μm range. Therefore, in the design of the antireflection film for the chalcogenide glass substrate in the 7 - 14 μm range, emphasis should be placed on the antireflection optimization of the film structure in the 12 - 14 μm band. The optimized film system has a low reflectivity in the 12 - 14 μm range, but the reflectivity at 7 μm is relatively high. So, it is necessary to further optimize the antireflection rate at 7 μm. Thus, the film system with optimized antireflection rate in the 12 - 14 μm range is used as the front film system, and the film system with further optimized antireflection rate at 7 μm is used as the back film system. Consequently, the transmittance of the chalcogenide glass substrate together with the determined front and back film systems in the 7 - 14 μm range meets the requirements.

[0009] In the design method of a highly efficient antireflection film for a chalcogenide glass substrate in the 7 - 14 μm range according to the present disclosure, since chalcogenide glass is an amorphous semiconductor material, which results in its complex surface chemical properties, weak bonding force with coating materials, and sensitivity to temperature. The main reasons for the generation of stress in the film layer and the resulting looseness and peeling of the film layer are the large difference in the thermal expansion coefficient between chalcogenide glass and commonly used infrared coating materials. Therefore, the coating materials are selected. It is found that the more suitable coating temperature range for the chalcogenide glass substrate is between 90°C and 130°C. In this temperature range, the coating material with a relatively small difference in thermal expansion coefficient between the film material and the chalcogenide glass substrate is germanium. Followed by zinc selenide, zinc sulfide, ytterbium fluoride, and yttrium fluoride. However, the materials with relatively good bonding effects with the chalcogenide glass substrate are germanium and oxide materials suitable for infrared coating according to the light transmission range, such as yttrium oxide and aluminum oxide. According to the size of the expansion coefficient between materials and the bonding effect between materials, a four - layer film structure of Sub / Ge / ZnSe / YbF 3 / ZnS / AIR is designed, thereby satisfying the bonding and expansion between the chalcogenide glass substrate and the film systems on each surface. In the design method of a highly efficient antireflection film for a chalcogenide glass substrate in the 7 - 14 μm range according to the present disclosure, the film systems on each surface adopt a four - layer film structure of Sub / Ge / ZnSe / YbF 3 / ZnS / AIR. On the basis of this design method, further implement, for example, the preparation method of a highly efficient antireflection film for a chalcogenide glass substrate in the 7 - 14 μm range according to the present disclosure. The transmittance of the accompanying coating pieces in the prepared lenses together with the film layer structures plated on both sides in the 7 - 14 μm band meets the requirements and can pass a total of five tests, namely the water immersion test, adhesion test, thermal shock test, salt spray test, and damp heat test, that is, it meets the requirements of strength and environmental adaptability and complies with the acceptance of GJB2485A - 2019.

[0010] In the design method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14μm band according to the present disclosure, the front film system and the back film system are film systems with the same film layers in the same order of the same film materials, and each film system has only four layers. Thus, each film system has a simple structure and few layers, which is convenient for design and optimization.

[0011] In the preparation method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14μm band according to the present disclosure, through steps S1 to S9, the transmissivity of the accompanying plating piece (i.e., the chalcogenide glass substrate) in the prepared lens together with the film system structures plated on both sides meets the requirements in the 7-14μm band.

[0012] Similarly, in the preparation method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14μm band according to the present disclosure, the accompanying plating piece in the prepared lens together with the film layer structures plated on both sides can pass five tests, namely the water immersion test, the adhesion test, the thermal shock test, the salt spray test, and the damp heat test, that is, it meets the requirements of strength and environmental adaptability and complies with the acceptance of GJB2485A-2019.

[0013] Similarly, in the preparation method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14μm band according to the present disclosure, the front film system and the back film system are film systems with the same film layers in the same order of the same film materials, and each film system has only four layers. Thus, each film system has a simple structure and few layers, which is convenient for preparation, with low preparation cost and high efficiency. Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of the two-sided film system of the design method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14μm band according to the present disclosure.

[0015] Figure 2 It is the transmittance curve graph of the chalcogenide glass substrate before coating in Example 1.

[0016] Figure 3 It is the reflectance curve graph of the chalcogenide glass substrate together with the front film system after optimizing the antireflection rate in the 12-14μm band in the design method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14μm band in Example 1.

[0017] Figure 4 It is the reflectance curve graph of the chalcogenide glass substrate together with the back film system after optimizing the reflectance at 7μm in the design method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14μm band in Example 1.

[0018] Figure 5 It is the transmittance curve graph of the chalcogenide glass substrate together with the determined front film system and back film system in the design method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14μm band in Example 1.

[0019] Figure 6It is a graph of the transmittance of the accompanying plating piece of Example 1 and the film stack structure plated on both sides in the 7-14 μm long-wave infrared band. Detailed implementation manners

[0020] It will be understood that the disclosed embodiments are merely examples of the present disclosure, and the present disclosure can be implemented in various forms. Therefore, the specific details disclosed herein should not be construed as limiting, but only as a basis for the claims and as a representative basis for teaching those of ordinary skill in the art to implement the present disclosure in various ways.

[0021] [Design method of high-efficiency antireflection film for chalcogenide glass substrate in 7-14 μm wavelength range]

[0022] The design method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14 μm wavelength range according to the present disclosure includes the steps:

[0023] Sa, Select 11 μm as the reference wavelength for the film thickness of the 1 / 4 wavelength film layer in the optical thin film design, and use the film stack expression: Sub / 0.1H / M / 0.6L / 0.15W / AIR. The same film layer sequence of the same film material is plated on the front and back of Sub.

[0024] Among them, Sub is the chalcogenide glass substrate, AIR represents air, H represents the high refractive index material Ge (germanium) with a 1 / 4 wavelength thickness, L represents the low refractive index material YbF 3 (ytterbium fluoride), M represents the intermediate refractive index material ZnSe (zinc selenide) with a 1 / 4 wavelength thickness, and W represents the intermediate refractive index material ZnS (zinc sulfide) with a 1 / 4 wavelength thickness;

[0025] Sb, Through the design software, optimize the film thickness of the single film layer of the four-layer film stack structure of Sub / Ge / ZnSe / YbF 3 / ZnS / AIR to obtain the initial film thickness of the film layer. Then, based on the initial film thickness of the film layer, optimize the antireflection rate in the 12-14 μm band and determine the optimal film thickness of the front film system. Finally, based on the optimal film thickness of the front film system, optimize the reflectance at 7 μm and determine the optimal film thickness of the back film system. Based on the determined front film system and back film system (refer to Figure 1 ), the transmittance of the chalcogenide glass substrate in the 7-14 μm long-wave infrared band meets the requirements;

[0026] Sc, Input the optimal film thicknesses of the determined front film system and back film system into the control computer of the coating machine.

[0027] In the design method of the high-efficiency antireflection film for the chalcogenide glass substrate in the 7-14 μm wavelength range according to the present disclosure, since there is a large absorption in the chalcogenide glass after 12 μm (for example, refer toFigure 2 ), the transmittance at 12 - 14 μm will be relatively low, resulting in a relatively low overall infrared transmission energy in the range of 7 - 14 μm. Therefore, in the design of the antireflection coating for the chalcogenide glass substrate in the range of 7 - 14 μm, emphasis should be placed on optimizing the antireflection of the film structure in the 12 - 14 μm band. The optimized film system has a relatively low reflectance at 12 - 14 μm (for example, refer to Figure 3 ), but the reflectance at 7 μm will be relatively high. Therefore, it is necessary to further optimize the antireflection rate at 7 μm (for example, refer to Figure 4 ). Thus, the film system with optimized antireflection rate in the range of 12 - 14 μm is used as the front film system, and the film system with further optimized antireflection rate at 7 μm is used as the back film system. Consequently, the transmittance of the chalcogenide glass substrate together with the determined front and back film systems in the range of 7 - 14 μm (for example, refer to Figure 5 ) meets the requirements.

[0028] In the design method of the 7 - 14 μm high - efficiency antireflection coating for the chalcogenide glass substrate according to the present disclosure, since chalcogenide glass is an amorphous semiconductor material, which leads to complex surface chemical properties, weak bonding force with coating materials, and sensitivity to temperature, and the large difference in thermal expansion coefficient between it and common infrared coating materials results in stress in the film layer, causing the film layer to be unstable and peel off. Therefore, the coating materials are selected. It is found that the suitable coating temperature range for the chalcogenide glass substrate is between 90 °C and 130 °C. Within this temperature range, the coating material with a relatively small difference in thermal expansion coefficient between the film material and the chalcogenide glass substrate is germanium, followed by zinc selenide, zinc sulfide, ytterbium fluoride, and yttrium fluoride. However, the materials with relatively good bonding effect with the chalcogenide glass substrate are germanium and oxide materials suitable for infrared coating according to the light - transmission range, such as yttrium oxide and aluminum oxide. According to the size of the expansion coefficient between materials and the bonding effect between materials, a four - layer film structure of Sub / Ge / ZnSe / YbF 3 / ZnS / AIR is designed, thereby satisfying the bonding and expansion between the chalcogenide glass substrate and the film systems on each surface. In the design method of the 7 - 14 μm high - efficiency antireflection coating for the chalcogenide glass substrate according to the present disclosure, the film system on each surface adopts a four - layer film structure of Sub / Ge / ZnSe / YbF 3 / ZnS / AIR. On the basis of this design method, further implement the preparation method of the 7 - 14 μm high - efficiency antireflection coating for the chalcogenide glass substrate according to the present disclosure as described later. The transmittance of the co - coated sheet in the prepared lens together with the film layer structures coated on both sides in the 7 - 14 μm band meets the requirements and can pass five tests, namely, the water - immersion test, adhesion test, thermal shock test, salt - spray test, and damp - heat test, that is, it meets the requirements of strength and environmental adaptability and complies with the acceptance of GJB2485A - 2019.

[0029] In the design method of the high-efficiency antireflection film for chalcogenide glass substrates in the 7-14 μm range according to the present disclosure, the front film system and the back film system are film systems with the same film materials and the same film layer sequence, and each film system has only four layers. Thus, each film system has a simple structure and few layers, which is convenient for design and optimization.

[0030] For example, in step Sa, the chalcogenide glass substrate is VIG06.

[0031] In one example,

[0032] In step Sb, for the front film system of the chalcogenide glass substrate, the film thickness of the optimal film layer

[0033] is:

[0034] The film thickness of the first Ge film layer is 58.5 nm ± 3 nm,

[0035] The film thickness of the second ZnSe film layer is 1231.30 ± 3 nm,

[0036] The film thickness of the third YbF 3 film layer is 1109.45 nm ± 3 nm,

[0037] The film thickness of the fourth ZnS film layer is 190 ± 3 nm;

[0038] In step Sb, for the back film system of the chalcogenide glass substrate, the film thickness of the optimal film layer

[0039] is:

[0040] The film thickness of the first Ge film layer is 58.5 nm ± 3 nm,

[0041] The film thickness of the second ZnSe film layer is 1168.15 ± 3 nm,

[0042] The film thickness of the third YbF 3 film layer is 1109.45 nm ± 3 nm,

[0043] The film thickness of the fourth ZnS film layer is 150 ± 3 nm;

[0044] In step Sb, the average transmittance of the chalcogenide glass substrate in the 7-14 μm long-wave infrared band reaches 98%, and the average transmittance in the 8-12 μm long-wave infrared band reaches 99.5%.

[0045] For example, in steps Sa to Sc, the design software is TFCalc or Essential Macleod.

[0046] [Preparation method of high-efficiency antireflection film for chalcogenide glass substrates in the 7-14 μm range]

[0047] The preparation method of the 7-14μm high-efficiency antireflection film for chalcogenide glass substrate according to the present disclosure includes the steps:

[0048] S1, configuring the film system process parameters of the coating machine and preparing four kinds of film materials including Ge, ZnSe, ZnS, and YbF. The configuration of the film system process parameters includes the background vacuum degree, temperature, the film thickness of the optimal film layer, the evaporation mode of the film material, the deposition rate of the film material, and the use of ion source assisted deposition. Among them, the film thickness of the film layer in the film system process parameters is based on the optimal film thickness of the film layer stored in the control computer of the coating machine in the design method of the 7-14μm high-efficiency antireflection film for chalcogenide glass substrate described above. 3 S2, cleaning the accompanying coating piece and the product of the chalcogenide glass substrate used as the lens before plating.

[0049] S3, putting the cleaned lens into the tooling fixture, hanging the tooling fixture with the lens placed in it into the cavity of the coating machine, and slowly heating and baking after evacuating the vacuum.

[0050] S4, pre-melting all the film materials to release gas and remove impurities and keep them at a constant temperature.

[0051] S5, cleaning the lens with the ion source.

[0052] S6, depositing and monitoring the film layer, depositing the film layer on the front side of the lens according to the film system parameter configuration in step S1.

[0053] S7, keeping at a constant temperature after plating.

[0054] S8, cooling down and taking out the parts.

[0055] S9, repeating steps S1 to S8 to deposit the film layer on the reverse side of the lens.

[0056] In the preparation method of the 7-14μm high-efficiency antireflection film for chalcogenide glass substrate according to the present disclosure, through steps S1 to S9, the transmittance of the accompanying coating piece (i.e., the chalcogenide glass substrate) in the prepared lens together with the deposited film system structure on both sides meets the requirements in the 7-14μm band.

[0057] Similarly, in the preparation method of the 7-14μm high-efficiency antireflection film for chalcogenide glass substrate according to the present disclosure, the accompanying coating piece in the prepared lens together with the deposited film layer structures on both sides can pass five tests including the water immersion test, adhesion test, thermal shock test, salt spray test, and damp heat test, that is, meet the strength and environmental adaptability requirements and comply with the acceptance of GJB2485A-2019.

[0058]

[0059] ​Similarly, in the method for preparing a 7-14μm high-efficiency antireflection film on a chalcogenide glass substrate according to the present disclosure, the front film system and the back film system are film systems with the same film layers in the same order of film materials and each film system has only four layers. Thus, each film system has a simple structure, few layers, is easy to prepare, has a low preparation cost and high efficiency.

[0060] In one example, in step S1, the base vacuum is (6.0 - 8.0)×10 -4 Pa; the temperature is set to be heated from 25°C to 120°C, and the heating gradient time is controlled to be 35 - 40 min. After the temperature reaches 120°C, it is kept at a constant temperature for 30 min; the film thickness of the film layers in the film system process parameters is based on the optimal film thickness of the film layers stored in the control computer of the coating machine in the design method of the 7-14μm high-efficiency antireflection film on the chalcogenide glass substrate described above; the evaporation mode of the film materials is as follows: the Ge film material is placed in a crucible and evaporated by electron beam heating, and the ZnSe film material, ZnS film material, and YbF 3 film materials are each placed in a molybdenum boat and evaporated by resistance heating; the deposition rate of the film materials is: the deposition rate of the Ge film layer is the deposition rate of the ZnSe film layer is the deposition rate of the ZnS film layer YbF 3 the deposition rate when depositing the film layer is set to The use of ion source assisted deposition is as follows: the first Ge film layer and the third YbF 3 film layer of the front film system and the back film system use ion source assistance, and the remaining film layers are not deposited with ion source assistance. Using ion source assisted deposition can make the film layer more dense, the first Ge film layer combines firmly with the chalcogenide glass substrate, the third YbF 3 film layer combines firmly with the second ZnSe and improves moisture resistance and durability. The remaining film layers of the outermost layer do not use ion source assisted deposition to ensure the quality and uniformity of the film layer structure. The above temperature setting (corresponding to the baking in step S3) can reduce the stress of the film layer structure and improve the adhesion of the film layer structure on the chalcogenide glass substrate.

[0061] Furthermore, in one example, the ion source is a Hall ion source. The ion source parameters when depositing the first Ge film layer are: neutralization current 0.5 A, neutralization gas flow rate 8 sccm, anode voltage 150 V, anode current 1.5 A, and argon gas flow rate ratio 100%; the ion source parameters when depositing the third YbF 3 film layer are: neutralization current 0.5 A, neutralization gas flow rate 8 sccm, anode voltage 100 V, anode current 1 A, and argon gas flow rate ratio 100%.

[0062] In step S1, for example, the coating machine is Guotai GTV-1350.

[0063] In step S2, for example, cleaning is performed by ultrasonic isopropyl alcohol cleaning or manual wiping. After cleaning, the lens is placed in a tooling fixture, and the tooling fixture with the lens is hung into the cavity of the coating machine and completed within 30 minutes. When the time exceeds 30 minutes, it needs to be cleaned again. When waiting for a long time to coat, the lens is stored in a nitrogen cabinet or a vacuum chamber. For example, the film thickness of the accompanying coating piece is 1.0 mm.

[0064] The baking in step S3 heats the lens, fully eliminates the water vapor on the surface of the chalcogenide glass substrate, can reduce the stress of the film layer structure, and improve the adhesion of the film layer structure on the chalcogenide glass substrate. In one example, in step S3, first evacuate to 5×10 -2 Pa, and then the cavity of the coating machine starts heating for the baking, and the heating is carried out according to the temperature in step S1.

[0065] The pre-melting of the film material in step S4 can release the gas in the film material and remove the impurities in the film material, ensuring the purity of the film material, thereby reducing the adverse factors that affect the quality of the film layer during the film layer coating process in the subsequent step S6. In one example, in step S4, when the vacuum extraction reaches (4.0 - 8.0)×10 -3 Pa, the film material is pre-melted. After the pre-melting of the film material is completed, when the temperature of the cavity of the coating machine reaches 120°C, keep it at a constant temperature for 30 minutes. The pre-melting treatment adopts two methods of electron beam heating and resistance heating. The Ge film material is pre-melted by electron beam heating, and the ZnSe film material, ZnS film material and YbF 3 film material are pre-melted by resistance heating.

[0066] The ion source cleaning in step S5 uses the source ion bombardment to clean the microscopic structure of the lens surface, which can eliminate the surface oxide layer, make the surface cleaner, and is conducive to the firm adhesion and growth of the film layer. Specifically, in one example, in step S5, when the vacuum degree of the coating machine reaches the base vacuum degree, the ion source of the vacuum coating machine is started. The ion source is a Hall ion source, and the parameters of the ion source are: the neutralization current is 0.5 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 150 V, the anode current is 1.5 A, the argon gas flow rate ratio is 100%, and the cleaning duration is 10 minutes.

[0067] In step S6, for example, in step S6, the film thickness of the film layer is monitored using the crystal oscillator method with the corresponding crystal oscillator of multiple crystal oscillators of the crystal controller. After the ion source cleaning, the crystal controller controls the new crystal oscillator among the multiple crystal oscillators to work correspondingly, and the crystal oscillator frequency is not less than 5.7 MHz.

[0068] The post-deposition constant temperature holding in step S7 is used to improve the quality, performance and stability of the film layer structure. In one example, after the coating is completed, the cavity is kept at a constant temperature of 120°C for 15 minutes.

[0069] The temperature reduction and workpiece taking in step S8 prevent the workpiece taking temperature of the lens from being too high, which may affect the film layer quality and stability. In one example, after the constant temperature in step S7 ends, the coating machine shuts down the baking under a vacuum state, and the temperature of the cavity of the coating machine naturally cools to below 50 °C or room temperature, and then the door is opened to take the workpiece.

[0070] [Test]

[0071] Example 1

[0072] Part 1: Design method of 7-14 μm high-efficiency antireflection film for chalcogenide glass substrate

[0073] The design method of the 7-14 μm high-efficiency antireflection film for the chalcogenide glass substrate in Example 1 adopts the following steps:

[0074] Sa, Select 11 μm as the reference wavelength for the film thickness of the 1 / 4 wavelength film layer in the optical thin film design, and use the film stack expression: Sub / 0.1H / M / 0.6L / 0.15W / AIR. The front and back sides of Sub are coated with the same film stack with the same film layer sequence of the same film material.

[0075] Among them, Sub is the chalcogenide glass substrate VIG06, AIR represents air, H represents the high refractive index material Ge (germanium) with a 1 / 4 wavelength thickness, L represents the low refractive index material YbF 3 (ytterbium fluoride), M represents the intermediate refractive index material ZnSe (zinc selenide) with a 1 / 4 wavelength thickness, and W represents the intermediate refractive index material ZnS (zinc sulfide) with a 1 / 4 wavelength thickness;

[0076] Sb, Use design software to optimize the film thickness of the single-sided film layer of the four-layer film stack structure of Sub / Ge / ZnSe / YbF 3 / ZnS / AIR to obtain the preliminary film thickness of the film layer. Then, based on the preliminary film thickness of the film layer, optimize the antireflection rate in the 12-14 μm band (refer to Figure 3 ) and determine the optimal film thickness of the front film stack. Finally, based on the optimal film thickness of the front film stack, optimize the reflectance at 7 μm (refer to Figure 4 ) and determine the optimal film thickness of the back film stack. Based on the determined front film stack and back film stack (refer to Figure 1 ), the transmittance of the chalcogenide glass substrate in the 7-14 μm long-wave infrared band (refer to Figure 5 ) meets the requirements.

[0077] Among them,

[0078] In step Sb, for the front film stack of the chalcogenide glass substrate, the optimal film thickness of the film layer is:

[0079] The film thickness of the first Ge film layer is 58.5 nmnm,

[0080] The film thickness of the second ZnSe film layer is 1231.30 nm,

[0081] The third YbF 3 The film thickness of the film layer is 1109.45 nm3nm,

[0082] The film thickness of the fourth ZnS film layer is 190 nm;

[0083] In step Sb, for the reverse film system of the chalcogenide glass substrate, the film thickness of the optimal film layer

[0084] is:

[0085] The film thickness of the first Ge film layer is 58.5 nmnm,

[0086] The film thickness of the second ZnSe film layer is 1168.15 nm,

[0087] The third YbF 3 The film thickness of the film layer is 1109.45 nmnm,

[0088] The film thickness of the fourth ZnS film layer is 150 nm;

[0089] Sc, input the film thicknesses of the optimal film layers of the determined front film system and reverse film system into the control computer of the coating machine, and the coating machine is Guotai GTV-1350;

[0090] In steps Sa to Sc, the design software is TFCalc.

[0091] Part Two: Preparation Method of 7-14μm High-Efficiency Antireflection Film for Chalcogenide Glass Substrate

[0092] The preparation method of the 7-14μm high-efficiency antireflection film for the chalcogenide glass substrate in Example 1 adopts the following steps:

[0093] S1, configuration of the film system process parameters of the coating machine and preparation of four film materials including Ge, ZnSe, ZnS, and YbF 3 The configuration of the film system process parameters includes the background vacuum degree, temperature, film thickness of the optimal film layer, evaporation mode of the film material, deposition rate of the film material, and use of ion source assisted deposition. Among them, the film thickness of the film layer in the film system process parameters is based on the film thickness of the optimal film layer stored in the control computer of the coating machine in the design method of the 7-14μm high-efficiency antireflection film for the chalcogenide glass substrate in the aforementioned Part One,

[0094] Among them,

[0095] The coating machine is Guotai GTV-1350;

[0096] The base vacuum degree is 8.0×10 -4 Pa;

[0097] The temperature is set to be heated from 25°C to 120°C, the temperature rising gradient time is controlled to be 40 min, and after the temperature reaches 120°C, it is kept at a constant temperature for 30 min;

[0098] The film thickness of the film layer in the film system process parameters is based on the optimal film thickness of the film layer stored in the control computer of the coating machine according to the design method of the 7-14μm high-efficiency antireflection film on the chalcogenide glass substrate in the aforementioned first part;

[0099] The evaporation mode of the film material is as follows: The Ge film material is placed in a crucible and evaporated by electron beam heating, and the ZnSe film material, ZnS film material and YbF 3 Each film material is placed in a molybdenum boat and evaporated by resistance heating;

[0100] The deposition rate of the film material is: The deposition rate of the Ge film layer is The deposition rate of the ZnSe film layer is The deposition rate of the ZnS film layer YbF 3 The deposition rate when depositing the film layer is set to

[0101] The use of ion source assisted deposition is as follows: The first Ge film layer and the third YbF film layer of the front film system and the back film system use ion source assistance, and the remaining film layers do not use ion source assisted deposition. Among them, the ion source is a Hall ion source. The ion source parameters when depositing the first Ge film layer are: neutralization current 0.5 A, neutralization gas flow rate 8 sccm, anode voltage 150 V, anode current 1.5 A, and argon gas flow rate ratio 100%; The ion source parameters when depositing the third YbF film layer are: neutralization current 0.5 A, neutralization gas flow rate 8 sccm, anode voltage 100 V, anode current 1 A, and argon gas flow rate ratio 100%; 3 The ion source parameters when depositing the third YbF film layer are: neutralization current 0.5 A, neutralization gas flow rate 8 sccm, anode voltage 100 V, anode current 1 A, and argon gas flow rate ratio 100%; 3 For S2, before plating, the accompanying plating pieces and products of the chalcogenide glass substrate used as the lens are cleaned. Among them, the cleaning is carried out by ultrasonic isopropyl alcohol cleaning. The cleaned lens is placed in a tooling fixture, and the tooling fixture with the lens placed is hung into the cavity of the coating machine and completed within 30 min. The film thickness of the film layer of the accompanying plating piece is 1.0 mm;

[0102] For S3, the cleaned lens is placed in a tooling fixture, and the tooling fixture with the lens placed is hung into the cavity of the coating machine, and then evacuated and slowly heated and baked. Among them, the evacuation and slow heating and baking are as follows: First evacuate to 5×10

[0103] Pa, and then the cavity of the coating machine starts heating for the baking, and the heating is carried out according to the temperature in step S1; -2 Pa, and then the cavity of the coating machine starts heating for the baking, and the heating is carried out according to the temperature in step S1;

[0104] S4. When the vacuum extraction reaches 6.0×10 -3 Pa, pre-melt all the film materials. The pre-melting treatment adopts two methods: electron beam heating and resistance heating. The Ge film material is pre-melted by electron beam heating, and the ZnSe film material, ZnS film material and YbF 3 film material are pre-melted by resistance heating. After the film materials are pre-melted, wait until the temperature of the cavity of the coating machine reaches 120°C and keep the constant temperature for 30 min;

[0105] S5. When the vacuum degree of the coating machine reaches the base vacuum degree, start the ion source of the vacuum coating machine to clean the lens. The ion source is a Hall ion source, and the parameters of the ion source are: the neutralization current is 0.5 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 150 V, the anode current is 1.5 A, the argon gas flow rate ratio is 100%, and the cleaning duration is 10 min;

[0106] S6. Film layer deposition and monitoring. Deposit the film layer on the front side of the lens according to the film system parameters and process configuration in step S1. Among them, use the crystal oscillator method to monitor the film thickness of the film layer with the corresponding crystal oscillator of multiple crystal oscillators of the crystal controller. After the ion source cleaning, the crystal controller controls the new crystal oscillator among multiple crystal oscillators to work correspondingly, and the crystal oscillator frequency is not less than 5.7 MHz;

[0107] S7. After the deposition is completed, keep the cavity at a constant temperature of 120°C for 15 min;

[0108] S8. After the constant temperature in step S7 ends, turn off the baking under the vacuum extraction state of the coating machine, and let the temperature of the cavity of the coating machine naturally cool to below 50°C or normal temperature, then open the door to take out the workpiece;

[0109] S9. Repeat steps S1 to S8 to deposit the film layer on the back side of the lens.

[0110] Figure 5 It is the transmittance curve graph of the chalcogenide glass substrate together with the determined front film system and back film system in the design method of the 7-14 μm high-efficiency antireflection film on the chalcogenide glass substrate in Example 1. Based on Figure 5 , the average transmittance of the chalcogenide glass substrate in the 7-14 μm long-wave infrared band reaches 98%, and the average transmittance in the 8-12 μm long-wave infrared band reaches 99.5%.

[0111] Figure 6 It is the transmittance curve graph of the accompanying coating piece in Example 1 together with the film system structure deposited on both sides in the 7-14 μm long-wave infrared band. Based on Figure 6 , the average transmittance of the chalcogenide glass substrate in the 7-14 μm long-wave infrared band reaches 95.4%, and the average transmittance in the 8-12 μm long-wave infrared band reaches 98.3%.

[0112] After double-sided coating of Example 1, the following tests were carried out.

[0113] Water bubble test: Take an appropriate amount of tap water for a 2-hour water bubble test, and observe whether the film layers on each surface peel off from the co-deposited pieces and whether the film layers on each surface crack.

[0114] Adhesion test: Stick 3M tape on each surface of the co-deposited piece by hand and pull the tape in the direction opposite to the sticking end (the pulling frequency is not less than 10 times), and observe whether the film layer is pulled up.

[0115] Thermal shock test: In a high and low temperature chamber, conduct thermal shock in the range of -46°C to 71°C for 24 hours, and observe whether the film layers on each surface of the co-deposited piece peel off and whether the film layers on each surface of the co-deposited piece crack.

[0116] Salt spray test: Conduct a neutral salt spray test for 48 hours, and observe whether the film layers on each surface of the co-deposited piece peel off and whether the film layers on each surface of the co-deposited piece crack.

[0117] Humidity and heat test: Conduct the test at a temperature of 50°C and a relative humidity of 95% for 48 hours, and observe whether the film layers on each surface of the co-deposited piece peel off and whether the film layers on each surface of the co-deposited piece crack.

[0118] Table 1 gives the transmittance of Example 1 and the results of various tests

[0119] Table 1 Transmittance of Example 1 and the results of various tests

[0120]

[0121] Multiple exemplary embodiments are described using the detailed description above, but this document is not intended to be limited to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined together to form multiple additional combinations that are not shown for the sake of brevity.

Claims

1. A design method for a 7-14 μm high-efficiency antireflection film on a chalcogenide glass substrate, characterized in that: Includes steps: Sa, 11μm is selected as the reference wavelength for the thickness of the 1 / 4 wavelength film layer of the optical thin film design, and the film stack expression is used: Sub / 0.1H / M / 0.6L / 0.15W / AIR. The front and back sides of Sub are coated with the same film material and the same film layer sequence. Wherein, Sub is a chalcogenide glass substrate, AIR represents air, H represents a high refractive index material Ge (germanium) with a thickness of 1 / 4 wavelength, L represents a low refractive index material YbF3 (ytterbium fluoride) with a thickness of 1 / 4 wavelength, M represents an intermediate refractive index material ZnSe (zinc selenide) with a thickness of 1 / 4 wavelength, and W represents an intermediate refractive index material ZnS (zinc sulfide) with a thickness of 1 / 4 wavelength; Sb, the film thickness of the single-sided film layer of the four-layer film system structure of Sub / Ge / ZnSe / YbF3 / ZnS / AIR generated by the input film stack formula is optimized through the design software to obtain the preliminary film thickness. Then, based on the preliminary film thickness, the anti-reflection rate in the 12-14μm band is optimized and the optimal film thickness of the front film system is determined. Finally, based on the optimal film thickness of the front film system, the reflectivity at 7μm is optimized and the optimal film thickness of the back film system is determined. Based on the determined front and back film systems, the transmittance of the chalcogenide glass substrate in the 7-14μm long-wave infrared band meets the requirements; Sc, input the optimal film thickness of the front film system and the back film system into the control computer of the coating machine.

2. The design method of the 7-14 μm high-efficiency antireflection film on a chalcogenide glass substrate according to claim 1, characterized in that: In step Sb, for the front film system of the chalcogenide glass substrate, the optimal film thickness of the film layer is: The thickness of the first Ge film layer is 58.5nm±3nm. The thickness of the second ZnSe film is 1231.30±3nm. The thickness of the third YbF3 film is 1109.45nm±3nm. The thickness of the fourth ZnS film layer is 190±3nm; In step Sb, for the reverse film system of the chalcogenide glass substrate, the optimal film thickness of the film layer is: The thickness of the first Ge film layer is 58.5nm±3nm. The thickness of the second ZnSe film is 1168.15±3nm. The thickness of the third YbF3 film is 1109.45nm±3nm. The thickness of the fourth ZnS film layer is 150±3nm; In step Sb, the average transmittance of the chalcogenide glass substrate in the 7-14 μm long-wave infrared band reaches 98%, and the average transmittance in the 8-12 μm long-wave infrared band reaches 99.5%.

3. The design method of 7-14 μm high-efficiency antireflection film on chalcogenide glass substrate according to claim 1, characterized in that: In step Sa, the chalcogenide glass substrate is VIG06; and / or In step Sa to step Sc, the design software is TFCalc or EssentialMacleod.

4. A method for preparing a 7-14 μm high-efficiency antireflection film on a chalcogenide glass substrate, characterized in that: Includes steps: S1, configuration of film system process parameters of the coating machine and preparation of four film materials, Ge, ZnSe, ZnS, and YbF3, wherein the configuration of film system process parameters includes background vacuum degree, temperature, optimal film thickness of the film layer, evaporation mode of the film material, deposition rate of the film material, and use of ion source assisted deposition, wherein the film thickness of the film layer in the film system process parameters is based on the optimal film thickness of the film layer stored in the control computer of the coating machine according to any one of claims 1-3; S2, before plating, the accompanying plating sheet and products of the chalcogenide glass substrate used as the lens are cleaned; S3, the cleaned lens is placed in a fixture, the fixture with the lens is hung in the cavity of the coating machine, and the vacuum is drawn and the temperature is slowly increased for baking; S4, pre-melting of all film materials, degassing, impurity removal and constant temperature; S5, ion source cleaning lens; S6, coating and monitoring the film layer, coating the film layer on the front side of the lens according to the film system parameter process configuration of step S1; S7, constant temperature maintenance after plating; S8, cooling and picking up; S9, repeating steps S1 to S8 to perform film coating on the reverse side of the lens.

5. The method for preparing a 7-14 μm high-efficiency antireflection film on a chalcogenide glass substrate according to claim 4, characterized in that: In step S1, The background vacuum degree is (6.0-8.0)×10 -4 Pa; The temperature is set to heat from 25°C to 120°C, the temperature gradient time is controlled to be 35-40min, and the temperature is kept constant for 30min after reaching 120°C; The film thickness of the film layer in the film system process parameters is based on the optimal film thickness of the film layer stored in the control computer of the coating machine according to claim 2; The evaporation mode of the film materials is as follows: the Ge film material is placed in a crucible and evaporated by electron beam heating, and the ZnSe film material, ZnS film material and YbF3 film material are placed in a molybdenum boat and evaporated by resistance heating; The deposition rate of the film material is: The deposition rate of the Ge film layer is The deposition rate of ZnSe film is Deposition rate of ZnS film The deposition rate of the YbF3 film was set to The use of ion source assisted deposition is as follows: the first Ge film layer and the third YbF3 film layer of the front film system and the back film system are assisted by ion source, and the remaining film layers are not deposited by ion source assisted deposition.

6. The method for preparing a 7-14 μm high-efficiency antireflection film on a chalcogenide glass substrate according to claim 5, characterized in that: The ion source is a Hall ion source. The ion source parameters when depositing the first Ge film layer are: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 150V, anode current 1.5A, and argon gas flow rate 100%; The ion source parameters when depositing the third YbF3 film layer are: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 100V, anode current 1A, and argon gas flow rate 100%.

7. The method for preparing a 7-14 μm high-efficiency antireflection film on a chalcogenide glass substrate according to claim 4, In step S1, the coating machine is Cathay Pacific GTV-1350; and / or In step S2, the cleaning is carried out by ultrasonic isopropyl alcohol cleaning or manual wiping. The cleaned lens is placed in a fixture and the fixture with the lens placed is hung in the cavity of the coating machine within 30 minutes. If the time exceeds 30 minutes, it needs to be cleaned again. If it takes a long time to wait for coating, the lens is stored in a nitrogen cabinet or a vacuum chamber; and / or The film thickness of the accompanying plating sheet is 1.0 mm.

8. The method for preparing a 7-14 μm high-efficiency antireflection film on a chalcogenide glass substrate according to claim 5, characterized in that: In step S3, First vacuum to 5×10 -2 Pa, then the cavity of the coating machine starts heating to perform the baking, and the heating is performed according to the temperature of step S1.

9. The method for preparing a 7-14 μm high-efficiency antireflection film on a chalcogenide glass substrate according to claim 8, characterized in that: In step S4, When the vacuum reaches (4.0-8.0)×10 -3 The film material is pre-melted at Pa. After the pre-melting of the film material is completed, the temperature of the cavity of the coating machine reaches 120℃ and is kept constant for 30 minutes. The pre-melting treatment adopts two methods: electron beam heating and resistance heating. The Ge film material is pre-melted by electron beam heating, and the ZnSe film material, ZnS film material and YbF3 film material are pre-melted by resistance heating.

10. The method for preparing a 7-14 μm high efficiency antireflection film on a chalcogenide glass substrate according to claim 5, characterized in that: In step S5, when the vacuum degree of the coating machine reaches the background vacuum degree, the ion source of the vacuum coating machine is started, the ion source is a Hall ion source, and the parameters of the ion source are: neutralization current is 0.5A, neutralization gas flow rate is 8sccm, anode voltage is 150V, anode current is 1.5A, argon gas flow rate ratio is 100%, and cleaning time is 10min; and / or In step S6, the film thickness of the film layer is monitored by using a corresponding crystal oscillator of a plurality of crystal oscillators of a crystal controller using a crystal oscillator method. After the ion source is cleaned, the crystal controller controls a new crystal oscillator of the plurality of crystal oscillators to work correspondingly, and the crystal oscillator frequency is not less than 5.7 MHz; and / or In step S7, after the plating is completed, the cavity is kept at a constant temperature of 120° C. for 15 minutes; and / or In step S8, after the constant temperature in step S7 is completed, the coating machine is closed for baking in a vacuum state, the temperature of the cavity of the coating machine is naturally cooled to below 50°C or room temperature, and the door is opened to take out the parts.

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