Design method and preparation method of chalcogenide glass substrate infrared short and medium wave 1.5-5 mu m durable antireflection film

Abstract

A design method and a preparation method of a chalcogenide glass substrate infrared short and medium wave 1.5-5 mu m durable anti-reflection film are provided. The design method of the chalcogenide glass substrate infrared short and medium wave 1.5-5 mu m durable anti-reflection film comprises the steps: Sa, selecting 3 mu m as the reference wavelength of the optical thin film design 1 / 4 wavelength thickness, using the film stack expression: Sub / 0.1W / 0.1L / 0.5H / 0.3L / 0.5M / 1L / 0.2W / AIR, Sub is plated with the same film system on both sides, wherein, Sub is chalcogenide glass substrate, AIR represents air, H represents Si, L represents YbF3, M represents ZnS, W represents Al2O3; Sb, generating the film layer structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air through the film stack expression; Sc, the best film thickness of the film layer is obtained by calculating and optimizing the film thickness of the film layer through the design software, and the optimized transmittance of the chalcogenide glass substrate in the infrared short and medium wave 1.5-5 mu m band meets the requirements; Sd, input the optimized film thickness of the film layer into 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 of a durable antireflection thin film for a chalcogenide glass substrate in the infrared short and medium wave 1.5-5 μm range. BACKGROUND

[0002] An infrared optical system usually adopts a crystal material, for example, ZnS, Si, GaAs, Ge, ZnSe, etc. The infrared lens of the crystal material is usually expensive. Chalcogenide glass is a new type of infrared lens material, which is a non-crystalline material based on sulfur, selenium and tellurium, and other elements (such as arsenic, antimony or germanium) are added. At present, chalcogenide glass can be used to prepare complex optical elements with consistent performance in a short time by a precision molding method. Due to high processing efficiency, the manufacturing cost and processing cycle of the infrared optical system are greatly reduced. These materials have unique optical properties in the infrared short, medium and long wave ranges, and the transmission waveband can cover three atmospheric windows of 1-3 μm, 3-5 μm and 8-12 μm. The application background of chalcogenide glass in the 1.5-5 μm waveband is closely related to the development and demand of infrared technology. With the wide application of infrared technology in the fields of military, security, environmental monitoring, medical imaging and scientific research, the demand for high-performance materials is increasing. Chalcogenide glass has become one of the indispensable materials in these application fields due to its excellent performance in the above waveband. In order to improve the light transmittance of the chalcogenide glass lens, an antireflection thin film needs to be coated on the surface thereof. Since the 1.5-5 μm waveband covers multiple atmospheric windows, it is crucial for applications such as thermal imaging and spectral analysis. However, most coating materials have different degrees of light absorption in the 1.5-5 μm range, resulting in low transmittance of the thin film. In addition, the chalcogenide glass is a non-crystalline material, which leads to complex surface stress and poor thin film firmness, etc. These problems have become technical problems to be solved in the field of optical thin film. SUMMARY

[0003] In view of the problems in the background art, one object of the present disclosure is to provide a design method and a preparation method of a durable antireflection thin film for a chalcogenide glass substrate in the infrared short and medium wave 1.5-5 μm range, which can make the transmittance of the chalcogenide glass substrate in the infrared short and medium wave 1.5-5 μm range meet the requirements.

[0004] Another object of the present disclosure is to provide a design method and a preparation method of a durable antireflection thin film for a chalcogenide glass substrate in the infrared short and medium wave 1.5-5 μm range, which can make the film layer structure on each surface of the chalcogenide glass substrate durable.

[0005] Thus, a design method of a durable antireflection thin film of a chalcogenide glass substrate for infrared short and medium wave 1.5-5 μm includes steps of: Sa, selecting 3 μm as a reference wavelength of 1 / 4 wavelength thickness for optical thin film design, using a film stack expression: Sub / 0.1W / 0.1L / 0.5H / 0.3L / 0.5M / 1L / 0.2W / AIR, Sub both sides are plated with the same film system, wherein Sub is a chalcogenide glass substrate, AIR represents air, H represents 1 / 4 wavelength thickness of high refractive index material Si (silicon), L represents 1 / 4 wavelength thickness of low refractive index material YbF3 (ytterbium fluoride), M represents 1 / 4 wavelength thickness of intermediate refractive index material ZnS (zinc sulfide), W represents 1 / 4 wavelength thickness of the bottom layer material and the outermost protective material Al2O3 (aluminum oxide); Sb, generating a film layer structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air by inputting the film stack expression; Sc, calculating and optimizing the film thickness of the film layer by the design software to obtain the optimal film thickness of the film layer, and the transmittance of the optimized chalcogenide glass substrate for infrared short and medium wave 1.5-5 μm band meets the requirements; Sd, inputting the optimized film thickness of the film layer into the control computer of the coating machine.

[0006] A preparation method of a durable antireflection thin film of a chalcogenide glass substrate for infrared short and medium wave 1.5-5 μm includes steps of: S1, cleaning the chalcogenide glass substrate for infrared short and medium wave 1.5-5 μm before coating and preparing Si, YbF3, ZnS, Al2O3 four kinds of film materials; S2, film system process parameter configuration, the film system process parameter configuration includes the vacuum degree, temperature, the optimal film thickness of the film layer, the evaporation mode of the film material, the deposition rate of the film material, the use of ion source assisted deposition before coating, and the thickness of the film layer in the film system process parameter 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 chalcogenide glass substrate for infrared short and medium wave 1.5-5 μm; S3, the cleaned lens is placed in the fixture, the fixture with the lens is hung in the cavity of the coating machine, vacuum baking and all film materials are pre-melted, degassed and kept at a constant temperature; S4, the ion source cleans the lens; S5, film layer coating and monitoring, the film layer is coated on the first side of the lens according to the film system parameter process configuration of step S2; S6, constant temperature keeping after coating; S7, cooling and taking out; S8, repeating steps S1 to S7 to coat the film layer on the second side of the lens.

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

[0008] In the design method of the sulfide glass substrate infrared short and medium wave 1.5-5 μm durable anti-reflection film according to the present disclosure, by adopting four film materials of Si, YbF3, ZnS and Al2O3, Si as a high refractive index material, YbF3 as a low refractive index material, ZnS as an intermediate refractive index material, Al2O3 as a bottom layer material of the film layer structure and a protective material of the outermost layer of the film layer structure, which plays a major role in preventing moisture, the second layer YbF3, the fourth layer YbF3, the sixth layer YbF3 and the third layer Si and the fifth layer ZnS form an alternation, which can make the designed sulfide glass substrate infrared short and medium wave 1.5-5 μm transmittance meet the requirements.

[0009] In the design method of the sulfide glass substrate infrared short and medium wave 1.5-5 μm durable anti-reflection film according to the present disclosure, the film layer structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air is adopted, as verified by the test in the preparation method, it can pass eight tests including abrasion resistance test, blister test, adhesion test, cold and hot impact test, constant temperature and humidity test, salt spray test, low temperature test and high temperature test, that is, the film layer structure (i.e. anti-reflection film) on each surface of the sulfide glass substrate obtained based on the design method and further based on the preparation method described below has good durability.

[0010] In the design method of the sulfide glass substrate infrared short and medium wave 1.5-5 μm durable anti-reflection film according to the present disclosure, the film layer structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air is a seven-layer structure, and the film layer structure is simple.

[0011] In the preparation method of the sulfide glass substrate infrared short and medium wave 1.5-5 μm durable anti-reflection film according to the present disclosure, the thickness of the film layer in the film system process parameters of step S1 to step S8 and step S2 is based on the optimal film thickness of the film layer stored in the control computer of the film coater in the design method of the sulfide glass substrate infrared short and medium wave 1.5-5 μm durable anti-reflection film described above, so that the prepared sulfide glass substrate infrared short and medium wave 1.5-5 μm transmittance meets the requirements.

[0012] Similarly, by adopting the film layer structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air, as verified by the test, it can pass eight tests including abrasion resistance test, blister test, adhesion test, cold and hot impact test, constant temperature and humidity test, salt spray test, low temperature test and high temperature test, that is, the film layer structure (i.e. anti-reflection film) on each surface of the sulfide glass substrate obtained based on the preparation method has good durability. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 This is a schematic diagram of the film structure according to the design method of the 1.5-5μm durable infrared short and medium wave antireflection film on the chalcogenide glass substrate disclosed herein.

[0014] Figure 2 This is a transmittance curve of the chalcogenide glass substrate with optimized film thickness and film layer structure on both sides, based on the design method of the 1.5-5μm durable infrared short and medium wave antireflection film on the chalcogenide glass substrate in Example 1.

[0015] Figure 3 This is a transmittance curve of the substrate and the film structure coated on both sides in the infrared short and medium wave 1.5-5μm band of Example 1. Detailed Implementation

[0016] It will be understood that the disclosed embodiments are merely examples of this disclosure, which can be implemented in various forms. Therefore, the specific details disclosed herein should not be construed as limiting, but are intended only as the basis for the claims and as an illustrative basis to teach those skilled in the art how to implement this disclosure in various ways.

[0017] [Design method for durable antireflective films with short to mid-wave infrared (1.5-5μm) on chalcogenide glass substrates]

[0018] The design method for durable antireflective films with infrared short and mid-wavelength (1.5-5 μm) on chalcogenide glass substrates according to this disclosure includes the following steps:

[0019] Sa, 3μm is selected as the reference wavelength for the 1 / 4 wavelength thickness of the optical thin film design, using the film stack expression: Sub / 0.1W / 0.1L / 0.5H / 0.3L / 0.5M / 1L / 0.2W / AIR, where Sub has the same film system deposited on both sides.

[0020] Wherein, Sub represents the chalcogenide glass substrate, AIR represents air, H represents the high refractive index material Si (silicon) with a thickness of 1 / 4 wavelength, L represents the low refractive index material YbF3 (ytterbium fluoride) with a thickness of 1 / 4 wavelength, M represents the intermediate refractive index material ZnS (zinc sulfide) with a thickness of 1 / 4 wavelength, and W represents the base layer material and the outermost protective material Al2O3 (alumina) with a thickness of 1 / 4 wavelength.

[0021] Sb, through the input film stack expression, generates a film structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air (refer to reference). Figure 1 );

[0022] Sc, by using design software to calculate and optimize the film thickness, the optimal film thickness was obtained. The optimized chalcogenide glass substrate has the required transmittance in the infrared short and medium wave 1.5-5μm band.

[0023] Sd inputs the optimized film thickness into the control computer of the coating machine.

[0024] In the design method of the 1.5-5μm durable infrared short and mid-wave transmittance film for chalcogenide glass substrate according to the present disclosure, four film materials are used: Si, YbF3, ZnS, and Al2O3. Si is used as a high refractive index material, YbF3 as a low refractive index material, ZnS as an intermediate refractive index material, and Al2O3 as the base material and outermost protective material of the film structure, playing a major role in moisture protection. The second, fourth, and sixth YbF3 layers are alternated with the third Si layer and the fifth ZnS layer, which enables the designed chalcogenide glass substrate to have infrared short and mid-wave transmittance of 1.5-5μm that meets the requirements.

[0025] In the design method of the 1.5-5μm durable infrared short and medium wave antireflection film on the chalcogenide glass substrate according to the present disclosure, the film structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air is adopted. As verified by the test in the preparation method, it can pass eight tests in total, including abrasion resistance test, water immersion test, adhesion test, thermal shock test, constant temperature and humidity test, salt spray test, low temperature test, and high temperature test. That is, the film structure (i.e., antireflection film) on each side of the chalcogenide glass substrate obtained based on the design method and further based on the preparation method described later has good durability.

[0026] In the design method of the 1.5-5μm durable infrared short and medium wave antireflection film on the chalcogenide glass substrate according to the present disclosure, the film structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air is a seven-layer structure, which is simple.

[0027] For example, in step Sa, the chalcogenide glass substrate is, but is not limited to, VIG04 or VIG06.

[0028] In one example, in step Sc, the optimal film thickness for each of the two sides of the chalcogenide glass substrate is as follows: the thickness of the first Al2O3 film is 20 nm ± 3 nm, the thickness of the second YbF3 film is 35.81 ± 3 nm, the thickness of the third Si film is 96.70 ± 3 nm, the thickness of the fourth YbF3 film is 116.78 ± 3 nm, the thickness of the fifth ZnS film is 103.45 ± 3 nm, the thickness of the sixth YbF3 film is 357.25 ± 3 nm, and the thickness of the seventh Al2O3 film is 40 ± 3 nm. Thus, the overall thickness of the film structure for each of the two sides of the chalcogenide glass substrate is relatively small, less than 800 nm, which effectively reduces costs and improves the coating efficiency of the preparation method described later.

[0029] Accordingly, in one example, in step Sc, the transmittance of the chalcogenide glass substrate in the infrared short-to-medium wave 1.5-5μm band is greater than 95% on average.

[0030] In steps Sa to Sd, the design software can be, but is not limited to, TFCalc or Essential Macleod.

[0031] [Preparation method of durable antireflective films with short and mid-wave infrared wavelengths of 1.5-5 μm on chalcogenide glass substrates]

[0032] The method for preparing a durable antireflective film with infrared short-to-mid wavelength (1.5-5 μm) on a chalcogenide glass substrate according to this disclosure includes the following steps:

[0033] S1, before coating, cleaning of the substrate and product used as the chalcogenide glass substrate for the lens, and preparation of four types of film materials: Si, YbF3, ZnS and Al2O3.

[0034] S2, Film system process parameter configuration, which includes pre-deposition base vacuum degree, temperature, optimal film thickness, film material evaporation mode, film material deposition rate, and the use of ion source-assisted deposition. 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 as described in the aforementioned design method for 1.5-5μm durable antireflective films for chalcogenide glass substrates.

[0035] S3, the cleaned lens is placed into the tooling fixture, the tooling fixture with the lens is hung into the cavity of the coating machine, vacuum baking, and all film materials are pre-melted, degassed, impurity removed and kept at a constant temperature.

[0036] S4, Ion source cleaning of lenses;

[0037] S5, Coating and monitoring: Coating is performed on the first surface of the lens according to the coating system parameters and process configuration in step S2.

[0038] S6, constant temperature maintenance after plating;

[0039] S7, cool down before picking up the part;

[0040] S8. Repeat steps S1 to S7 to apply a coating to the second surface of the lens.

[0041] In the method for preparing a durable antireflective film with infrared short and mid-wavelength (1.5-5 μm) on a chalcogenide glass substrate according to the present disclosure, the thickness of the film layer in the film system process parameters of steps S1 to S8 and step S2 is based on the optimal film thickness stored in the control computer of the coating machine as described in the design method of the aforementioned durable antireflective film with infrared short and mid-wavelength (1.5-5 μm) on a chalcogenide glass substrate, so that the transmittance of the prepared chalcogenide glass substrate with infrared short and mid-wavelength (1.5-5 μm) meets the requirements.

[0042] Similarly, by adopting the film structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air, as verified by the test, it can pass eight tests, including abrasion resistance test, water immersion test, adhesion test, thermal shock test, constant temperature and humidity test, salt spray test, low temperature test, and high temperature test. That is, the film structure (i.e., antireflective film) on each side of the chalcogenide glass substrate obtained by the preparation method has good durability.

[0043] The cleaning in step S1 helps improve the surface condition of the first and second surfaces of the lens, and contributes to enhancing the adhesion between the coating structure on each surface and the corresponding surface of the lens. For example, in step S1, cleaning is performed using ultrasonic cleaning and manual wiping. For example, ultrasonic cleaning uses ultrasonic alcohol or isopropanol. The chalcogenide glass substrate is, but is not limited to, VIG04 or VIG06. In one example, the thickness of the coating is 1.0 mm.

[0044] In one example, in step S2, the pre-plating base vacuum is 8.0 × 10⁻⁶. -4Pa; the temperature is set to heat from 25℃ to 120℃, with a heating gradient time controlled at 40-45 min; after reaching 120℃, the temperature is held constant for 20 min; 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 as described in the aforementioned design method for 1.5-5μm durable antireflective films for infrared short and mid-wave wavelengths on chalcogenide glass substrates. Specifically, for each of the two sides of the chalcogenide glass substrate, the optimal film thickness is: the thickness of the first Al2O3 film layer is 20±3nm, and the thickness of the second YbF3 film layer is... The thickness of the first film layer is 35.81±3 nm, the thickness of the third Si film layer is 96.70±3 nm, the thickness of the fourth YbF3 film layer is 116.78±3 nm, the thickness of the fifth ZnS film layer is 103.45±3 nm, the thickness of the sixth YbF3 film layer is 357.25±3 nm, and the thickness of the seventh Al2O3 film layer is 40±3 nm. The evaporation mode of the film materials is as follows: Si and Al2O3 are evaporated using electron beam heating, and YbF3 and ZnS are evaporated using resistance heating. The deposition rate of the film materials is as follows: the deposition rate of the Si film layer is... The deposition rate of the Al2O3 film is The deposition rate for YbF3 films was set to Deposition rate of ZnS film The use of ion source-assisted deposition is as follows: except for the deposition of the third Si film layer and the fifth ZnS film layer, ion source-assisted deposition is used for all other film layers.

[0045] Furthermore, in one example, the ion source parameters for depositing the first Al2O3 film layer are: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 180V, anode current 2A, and argon flow rate 100%; the ion source parameters for depositing the second YbF3 film layer are: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%; the ion source parameters for depositing the fourth YbF3 film layer are: neutralization current 0.5A, The ion source parameters for depositing the sixth YbF3 film layer were: neutralizing current 0.5A, neutralizing gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%. The parameters for depositing the seventh Al2O3 film layer were: neutralizing current 0.5A, neutralizing gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%. When depositing the first Al2O3 film layer as a base, the energy parameters for ion source-assisted deposition should be set slightly higher to enhance the adhesion of the base film. When depositing the final (seventh) Al2O3 film layer, which serves as the outermost protective layer and is thicker than the base layer, ion source-assisted evaporation should be used with slightly lower energy parameters to avoid excessive evaporation energy causing increased stress and the risk of film cracking.

[0046] For example, in step S2, the coating machine is a Cathay GTV-1350.

[0047] The baking in step S3 prepares the temperature for the pre-melting of the film material. Pre-melting releases gases from the film material and removes impurities, ensuring its purity and reducing adverse factors affecting film quality during the coating process in step S5. Furthermore, baking also heats the lens. Specifically, in one example, a vacuum is first drawn to 5×10⁻⁶. -2 Pa, then the cavity of the coating machine is heated to perform the baking, and the heating is performed according to the temperature in step S2; when the vacuum reaches (4.0-6.0)×10 -3 At Pa, the film material is pre-melted. After the film material is pre-melted, the temperature of the cavity of the coating machine reaches 120℃ and is kept constant for 10 minutes. In step S3, the pre-melting process adopts two methods: electron beam heating and resistance heating. The Si film material and Al2O3 film material are pre-melted by electron beam heating, while the ZnS film material and Al2O3 film material are pre-melted by resistance heating.

[0048] Step S4, ion source cleaning, utilizes ion bombardment to clean the surface microstructure of the lens, eliminating the oxide layer and making the lens surface cleaner, which is beneficial for the firm adhesion and growth of the film. Specifically, in one example, in step S4, the ion source is a Hall ion source with the following parameters: neutralization current 0.75A, neutralization gas flow rate 10 sccm, anode voltage 150V, anode current 1.5A, argon gas flow rate percentage 100%, and cleaning time set to 10 min.

[0049] In one example, in step S5, the film thickness is monitored by using the crystal oscillator method with the corresponding crystal oscillators of the multiple crystal oscillators of the crystal controller. After the ion source is cleaned, the crystal controller controls the new crystal oscillator among the multiple crystal oscillators to work accordingly, and the crystal oscillator frequency is not less than 5.99MHz.

[0050] In one example, in step S6, after the plating is completed, the cavity is kept at a constant temperature of 120°C for 10 minutes;

[0051] In one example, in step S7, the door is opened and the item is retrieved after the temperature drops below 60°C.

[0052] [test]

[0053] Example 1

[0054] Part 1: Design Methods for Durable Antireflective Films with Short-to-Mid-Wave Infrared Radiation (1.5-5μm) on Chalcogenide Glass Substrates

[0055] The design method for the 1.5-5 μm durable infrared short-to-mid wavelength antireflection film on a chalcogenide glass substrate in Example 1 follows these steps:

[0056] Sa, 3μm is selected as the reference wavelength for the 1 / 4 wavelength thickness of the optical thin film design, using the film stack expression: Sub / 0.1W / 0.1L / 0.5H / 0.3L / 0.5M / 1L / 0.2W / AIR, where Sub has the same film system deposited on both sides.

[0057] Wherein, Sub represents VIG06, a chalcogenide glass substrate; AIR represents air; H represents Si (silicon), a high refractive index material with a thickness of 1 / 4 wavelength; L represents YbF3 (ytterbium fluoride), a low refractive index material with a thickness of 1 / 4 wavelength; M represents ZnS (zinc sulfide), an intermediate refractive index material with a thickness of 1 / 4 wavelength; and W represents Al2O3 (alumina), a base material and an outermost protective material with a thickness of 1 / 4 wavelength.

[0058] Sb, through the input film stack expression, generates the film structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air;

[0059] Sc, by using design software to calculate and optimize the film thickness, the optimal film thickness was obtained. The optimized chalcogenide glass substrate has the required transmittance in the infrared short and medium wave 1.5-5μm band.

[0060] Sd inputs the optimized film thickness into the control computer of the coating machine, which is a Cathay GTV-1350.

[0061] in,

[0062] In step Sc, for each of the two sides of the chalcogenide glass substrate, the optimal film thickness is:

[0063] The thickness of the first Al2O3 film is 20 nm.

[0064] The thickness of the second YbF3 film is 35.81 nm.

[0065] The thickness of the third Si film is 96.70 nm.

[0066] The thickness of the fourth YbF3 film is 116.78 nm.

[0067] The thickness of the fifth ZnS film is 103.45 nm.

[0068] The thickness of the sixth YbF3 film is 357.25 nm.

[0069] The thickness of the seventh Al2O3 film is 40 nm;

[0070] In steps Sa to Sd, the software used for design is TFCalc.

[0071] Figure 2 This is a transmittance curve of the chalcogenide glass substrate with optimized film thickness and film structure on both sides, based on the design method of the 1.5-5μm durable infrared short- and mid-wave antireflection film on the chalcogenide glass substrate in Example 1. Figure 2 In step Sc, the average transmittance of the chalcogenide glass substrate in the infrared short and medium wave 1.5-5μm band is greater than 95%.

[0072] Part 2: Preparation method of durable antireflective films for short and mid-wave infrared wavelengths (1.5-5 μm) on chalcogenide glass substrates

[0073] The preparation method of the 1.5-5 μm durable infrared short-to-mid wavelength antireflection film on a chalcogenide glass substrate in Example 1 adopts the following steps:

[0074] S1. Before plating, ultrasonic cleaning of the substrate and the product, which is the chalcogenide glass substrate used as the lens, is carried out using alcohol. Four types of film materials, namely Si, YbF3, ZnS and Al2O3, are also prepared. The chalcogenide glass substrate is VIG06 and the thickness of the substrate is 1.0mm.

[0075] S2, Film system process parameter configuration. This includes pre-deposition background vacuum, temperature, optimal film thickness, vapor deposition mode, deposition rate, and the use of ion source-assisted deposition. The film thickness in the process parameters is based on the optimal film thickness stored in the coating machine's control computer, as described in the aforementioned design method for durable antireflective films with infrared short-to-mid-wave (1.5-5 μm) on chalcogenide glass substrates.

[0076] in,

[0077] The coating machine is a Cathay GTV-1350.

[0078] The initial vacuum level before plating was 8.0 × 10⁻⁶. -4 Pa;

[0079] The temperature was set to heat from 25℃ to 120℃, and the temperature gradient time was controlled to be 45 min.

[0080] Once the temperature reaches 120℃, maintain a constant temperature for 20 minutes.

[0081] 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 as described in the aforementioned design method for 1.5-5μm durable antireflective films for infrared short and medium waves on chalcogenide glass substrates.

[0082] The evaporation mode of the film material is as follows: Si and Al2O3 are evaporated by electron beam heating, while YbF3 and ZnS are evaporated by resistance heating.

[0083] The deposition rate of the film material is: the deposition rate of the Si film layer is The deposition rate of the Al2O3 film is The deposition rate for YbF3 films was set to Deposition rate of ZnS film

[0084] The use of ion source-assisted deposition is as follows: except for the deposition of the third Si film layer and the fifth ZnS film layer, ion source-assisted deposition is used for all other film layers.

[0085] The ion source parameters for depositing the first Al2O3 film layer were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 180V, anode current 2A, and argon gas flow rate 100%.

[0086] The ion source parameters for depositing the second YbF3 film were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%.

[0087] The ion source parameters for depositing the fourth YbF3 film layer were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%.

[0088] The ion source parameters for depositing the sixth YbF3 film layer were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%.

[0089] The ion source parameters for depositing the seventh Al2O3 film layer were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 150V, anode current 1.5A, and argon flow rate 100%.

[0090] S3: The cleaned lenses are placed into the tooling fixture, which is then hung inside the coating machine cavity. Vacuum baking, pre-melting of all coating materials, degassing, impurity removal, and temperature control are then performed.

[0091] In step S3,

[0092] First, evacuate to a vacuum level of 5×10. -2 Pa, then the cavity of the coating machine is heated to perform the baking, and the heating is performed according to the temperature in step S2;

[0093] When the vacuum reaches 5.0 × 10 -3 At Pa, the film material is pre-melted. After the film material is pre-melted, the temperature of the coating machine cavity reaches 120℃ and is maintained at a constant temperature for 10 minutes.

[0094] The pre-melting process employs two methods: electron beam heating and resistance heating. The Si film and Al2O3 film are pre-melted by electron beam heating, while the ZnS film and Al2O3 film are pre-melted by resistance heating.

[0095] S4, Ion source cleaning lens, the ion source is a Hall ion source, the parameters of the ion source are: neutralization current 0.75A, neutralization gas flow rate 10sccm, anode voltage 150V, anode current 1.5A, argon gas flow rate ratio 100%, cleaning time set to 10min.

[0096] S5, Film deposition and monitoring: Film deposition is performed on the first surface of the lens according to the film system parameters and process configuration in step S2. The film thickness is monitored by using the crystal oscillator method with the corresponding crystal oscillators of multiple crystal oscillators in the crystal controller. After cleaning with the ion source, the crystal controller controls the new crystal oscillator in the multiple crystal oscillators to work accordingly. The crystal oscillator frequency is not less than 5.99MHz.

[0097] S6, after plating, keep the cavity at a constant temperature of 120℃ for 10 minutes;

[0098] S7, wait for the temperature to drop to 60℃ before opening the door to retrieve the item;

[0099] S8. Repeat steps S1 to S7 to apply a coating to the second surface of the lens.

[0100] Comparative Example 1

[0101] Except for replacing Si with Ge as the high refractive index material in the first and second parts (i.e., only material replacement), the rest is the same as in Example 1.

[0102] Comparative Example 2

[0103] Except for replacing YbF3 with YF3 as a low-refractive-index material in Parts 1 and 2 (i.e., only material replacement), the rest is the same as in Example 1.

[0104] Comparative Example 3

[0105] Except for replacing ZnS with ZnSe as the medium refractive index material in the first and second parts (i.e., only material replacement), the rest is the same as in Example 1.

[0106] Comparative Example 4

[0107] Except for step S2 in Part 2, where the ion source parameters for depositing the seventh Al2O3 film are adjusted to be the same as those for depositing the first Al2O3 film (i.e., the ion source parameters for depositing the seventh Al2O3 film are increased to be the same as those for depositing the first Al2O3 film), the rest is the same as in Example 1.

[0108] Figure 3 This is a transmittance curve of the substrate and the film structure deposited on both sides in the infrared short and mid-wave 1.5-5μm band of Example 1. Based on Figure 3 The transmittance of the substrate and the film structure deposited on both sides in the infrared short and medium wave 1.5-5μm band is greater than 95% on average (specifically 95.5%).

[0109] In accordance with GJB2485A-2019, the following tests were conducted on both sides of Example 1 and Comparative Examples 1-4 after coating.

[0110] Friction resistance test (medium friction test): Wrap the rubber friction head of the rubber with degreased cloth and apply a pressure of 4.9N to the film surface of the coated sheet for 50 cycles (25 back and forth). Observe whether there are scratches or signs of damage on the film surface.

[0111] Water immersion test: Take tap water and conduct a water immersion test for 2 hours. Observe whether the film layer on each surface has fallen off from the substrate and whether the film layer on each surface has cracked.

[0112] Adhesion test: Apply 3M tape to each side of the coated sheet by hand and pull the tape in the opposite direction to the adhesive end. Observe whether the film layer is pulled up.

[0113] Thermal shock test: The film is subjected to thermal shock in the range of -40℃ to 85℃ for 24 hours in a high and low temperature chamber. Observe whether the film layer on each surface of the substrate is peeled off and whether the film layer on each surface of the substrate is cracked.

[0114] Constant temperature and humidity test: In a constant temperature and humidity chamber, at 50℃ and 95% relative humidity for 48 hours, observe whether the film layer on each surface of the substrate peels off and whether the film layer on each surface of the substrate cracks.

[0115] Salt spray test: Neutral salt spray test for 48 hours, observe whether the film layer on each surface of the substrate peels off, and observe whether the film layer on each surface of the substrate cracks.

[0116] Low temperature test: In a low temperature chamber, at -40℃ for 48 hours, observe whether the film layer on each surface of the substrate peels off and whether the film layer on each surface of the substrate cracks.

[0117] High temperature test: In a high temperature chamber, at 85℃ for 48 hours, observe whether the film layer on each surface of the substrate peels off and whether the film layer on each surface of the substrate cracks.

[0118] Table 1 shows the transmittance of Example 1 and Comparative Examples 1-4, as well as the results of various tests.

[0119] Table 1. Transmittance of Example 1 and Comparative Examples 1-4, and results of various tests.

[0120]

[0121] Several exemplary embodiments have been described in detail above, but this document is not intended to limit itself to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined to form several other combinations, which are not shown for simplicity.

Claims

1. A method for designing a durable antireflective film with infrared short-to-mid-wave (1.5-5 μm) on a chalcogenide glass substrate, characterized in that, Including the following steps: Sa, 3μm is selected as the reference wavelength for the 1 / 4 wavelength thickness of the optical thin film design, using the film stack expression: Sub / 0.1W / 0.1L / 0.5H / 0.3L / 0.5M / 1L / 0.2W / AIR, where Sub has the same film system deposited on both sides. Wherein, Sub represents the chalcogenide glass substrate, AIR represents air, H represents the high refractive index material Si (silicon) with a thickness of 1 / 4 wavelength, L represents the low refractive index material YbF3 (ytterbium fluoride) with a thickness of 1 / 4 wavelength, M represents the intermediate refractive index material ZnS (zinc sulfide) with a thickness of 1 / 4 wavelength, and W represents the base layer material and the outermost protective material Al2O3 (alumina) with a thickness of 1 / 4 wavelength. Sb, through the input film stack expression, generates the film structure of Sub / Al2O3 / YbF3 / Si / YbF3 / ZnS / YbF3 / Al2O3 / Air; Sc, by using design software to calculate and optimize the film thickness, the optimal film thickness was obtained. The optimized chalcogenide glass substrate has the required transmittance in the infrared short and medium wave 1.5-5μm band. Sd inputs the optimized film thickness into the control computer of the coating machine; In step Sa, the chalcogenide glass substrate is VIG04 or VIG06; In step Sc, for each of the two sides of the chalcogenide glass substrate, the optimal film thickness is: The thickness of the first Al2O3 film is 20±3 nm. The thickness of the second YbF3 film is 35.81±3 nm. The thickness of the third Si film is 96.70 ± 3 nm. The thickness of the fourth YbF3 film is 116.78±3 nm. The thickness of the fifth ZnS film is 103.45 ± 3 nm. The thickness of the sixth YbF3 film is 357.25 ± 3 nm. The thickness of the seventh Al2O3 film is 40±3 nm. In step Sc, the average transmittance of the chalcogenide glass substrate in the infrared short-to-medium wave 1.5-5μm band is greater than 95%.

2. A method for preparing a durable antireflective film with infrared short-to-mid-wave (1.5-5 μm) on a chalcogenide glass substrate, characterized in that, Including the following steps: S1. Before coating, the substrate and product used as the chalcogenide glass substrate for the lens are cleaned and prepared with four types of film materials: Si, YbF3, ZnS and Al2O3. The chalcogenide glass substrate is VIG04 or VIG06. S2, Film system process parameter configuration, the film system process parameter configuration includes pre-deposition base vacuum degree, temperature, optimal film thickness, film material evaporation mode, film material deposition rate, use of ion source assisted deposition, 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 1.5-5μm durable antireflective film for chalcogenide glass substrate according to claim 1; S3, the cleaned lens is placed into the tooling fixture, the tooling fixture with the lens is hung into the cavity of the coating machine, vacuum baking, and all film materials are pre-melted, degassed, impurity removed and kept at constant temperature. S4, Ion source cleaning of lenses; S5, Coating and monitoring: Coating is performed on the first surface of the lens according to the coating system parameters and process configuration in step S2. S6, constant temperature maintenance after plating; S7, cool down before picking up the part; S8. Repeat steps S1 to S7 to apply a coating to the second surface of the lens. In step S2, The use of ion source-assisted deposition is as follows: except for the deposition of the third Si film layer and the fifth ZnS film layer, ion source-assisted deposition is used for all other film layers. The ion source parameters for depositing the first Al2O3 film layer were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 180V, anode current 2A, and argon gas flow rate 100%. The ion source parameters for depositing the second YbF3 film were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%. The ion source parameters for depositing the fourth YbF3 film layer were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%. The ion source parameters for depositing the sixth YbF3 film layer were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 120V, anode current 1A, and argon flow rate 100%. The ion source parameters for depositing the seventh Al2O3 film were: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 150V, anode current 1.5A, and argon flow rate 100%.

3. The method for preparing a durable antireflective film with infrared short-to-mid-wave (1.5-5 μm) on a chalcogenide glass substrate according to claim 2, characterized in that, In step S1, Cleaning is performed using ultrasonic cleaning and manual wiping. The thickness of the plating sheet is 1.0 mm.

4. The method for preparing a durable antireflective film with infrared short-to-mid-wave (1.5-5 μm) on a chalcogenide glass substrate according to claim 2, characterized in that, In step S2, The initial vacuum level before plating was 8.0 × 10⁻⁶. -4 Pa; The temperature was set to heat from 25℃ to 120℃, with the temperature gradient time controlled at 40-45 min; after the temperature reached 120℃, it was kept constant for 20 min. The thickness of the film layer 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 1.5-5μm durable antireflective film for infrared short and medium wave on chalcogenide glass substrate as described in claim 1. The evaporation mode of the film material is as follows: Si and Al2O3 are evaporated by electron beam heating, while YbF3 and ZnS are evaporated by resistance heating. The deposition rate of the film material is: the deposition rate of the Si film layer is The deposition rate of the Al2O3 film is / s. The deposition rate for the YbF3 film was set to / s. / s, deposition rate of ZnS film / s.

5. The method for preparing a durable antireflective film with infrared short-to-mid-wave (1.5-5 μm) on a chalcogenide glass substrate according to claim 2, characterized in that, In step S3, First, evacuate to a vacuum level of 5×10. -2 Pa, then the cavity of the coating machine is heated to perform the baking, and the heating is performed according to the temperature in step S2; When the vacuum reaches (4.0-6.0)×10 -3 At Pa, the film material is pre-melted. After the film material is pre-melted, the temperature of the coating machine cavity reaches 120℃ and is maintained at a constant temperature for 10 minutes. In step S3, the pre-melting process employs both electron beam heating and resistance heating. The Si film and Al2O3 film are pre-melted using electron beam heating, while the ZnS film and Al2O3 film are pre-melted using resistance heating.

6. The method for preparing a durable antireflective film with infrared short-to-mid-wave (1.5-5 μm) on a chalcogenide glass substrate according to claim 2, characterized in that, In step S4, The ion source is a Hall ion source. The parameters of the ion source are: neutralization current 0.75A, neutralization gas flow rate 10sccm, anode voltage 150V, anode current 1.5A, argon flow rate 100%, and cleaning time set to 10min.

7. The method for preparing a durable antireflective film with infrared short-to-mid-wave (1.5-5 μm) on a chalcogenide glass substrate according to claim 2, characterized in that, In step S5, the film thickness is monitored by using the crystal oscillator method to monitor the corresponding crystal oscillators of the multiple crystal oscillators of the crystal controller. After the ion source is cleaned, the crystal controller controls the new crystal oscillator among the multiple crystal oscillators to work accordingly, and the crystal oscillator frequency is not less than 5.99MHz. In step S6, after the plating is completed, the cavity is kept at a constant temperature of 120°C for 10 minutes; In step S7, the door is opened and the item is retrieved once the temperature drops below 60°C.

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