Infrared short-wave medium-wave coating process for zinc selenide substrate

Abstract

The invention discloses an infrared short-wave medium-wave coating process for a zinc selenide substrate. The infrared short-wave medium-wave coating process for the zinc selenide substrate comprises the following steps: S1, cleaning a plating accompanying sheet and a product serving as the zinc selenide substrate of a lens before plating, and preparing three coating materials, namely YF3, ZnSe and Al2O3; s2, the cleaned lens is put into a tool clamp, the tool clamp with the lens is hung into a cavity of a coating machine, and vacuumizing baking and film material pre-melting are carried out; s3, cleaning the lens by an ion source; s4, under the vacuum condition, a first YF3 film layer, a second ZnSe film layer, a third YF3 film layer, a fourth ZnSe film layer, a fifth YF3 film layer and a sixth Al2O3 film layer are sequentially plated on the first face of the lens, the six film layers form a film system, ion source auxiliary deposition is not used for the first film layer, the second film layer, the third film layer and the fourth film layer, and ion source auxiliary deposition is used for the fifth YF3 film layer and the sixth Al2O3 film layer; s5, keeping at constant temperature after plating; s6, cooling and part taking; and S7, repeating the steps S1 to S6, and plating the same film system on the second surface of the lens.

Description

Technical Field

[0001] The present disclosure relates to the field of optical coating technology, and more specifically to an infrared short-wave and medium-wave coating process for a zinc selenide substrate. Background Art

[0002] In modern optical technology, infrared optical components are crucial in the fields of thermal imaging, night vision, gas detection and remote sensing. Among them, the demand for optical components in the mid-wave infrared (3-5μm) and short-wave infrared (1-2.5μm) regions is particularly significant, because these bands cover the unique absorption spectra of many substances and are the key to achieving high-precision detection and imaging. Zinc selenide (ZnSe), as a material with high transmittance in the mid-infrared band, is widely used as a substrate material for optical windows and lenses. However, although zinc selenide has good light transmittance in the mid-wave infrared and short-wave infrared regions, its surface has a high natural reflectivity, which limits the transmittance of light. In order to overcome this limitation and improve the transmittance of optical components in the 1.5-5μm band, multilayer coating technology is used to deposit thin films with specific optical properties on zinc selenide substrates, which can significantly reduce surface reflections and improve the transmittance in specific bands, thereby improving the overall performance of optical components.

[0003] At present, the design and coating technology of multilayer films, especially the high transmittance coating process for the mid-wave and short-wave infrared bands, is a hot topic in the field of optical coating research. Therefore, the development of a multilayer coating process that can achieve high transmittance in the 1.5-5μm band is of great significance for improving the performance of infrared optical components. Summary of the invention

[0004] In view of the problems existing in the background technology, an object of the present disclosure is to provide an infrared short-wave and medium-wave coating process for a zinc selenide substrate, which can be used to achieve high transmittance in the 1.5-5 μm band.

[0005] Another object of the present disclosure is to provide an infrared short-wave and medium-wave coating process for a zinc selenide substrate, which can be used to achieve acceptance in compliance with friction resistance tests, blister tests, adhesion tests, hot and cold shock tests, constant temperature and humidity tests, salt spray tests, low temperature tests, and high temperature tests.

[0006] Thus, an infrared short-wave and medium-wave coating process for a zinc selenide substrate includes the following steps: S1, before coating, cleaning the accompanying coating sheet and product of the zinc selenide substrate as a lens and preparing three kinds of film materials: YF3, ZnSe and Al2O3; S2, placing the cleaned lens into a fixture, hanging the fixture with the lens in place into the cavity of the coating machine, vacuum baking and pre-melting the film material; S3, cleaning the lens with an ion source; S4, coating the first surface of the lens in turn under vacuum conditions. The first YF3 film layer, the second ZnSe film layer, the third YF3 film layer, the fourth ZnSe film layer, the fifth YF3 film layer, and the sixth Al2O3 film layer constitute a film system. The first to fourth film layers are not deposited using an ion source to assist in deposition, while the fifth YF3 film layer and the sixth Al2O3 film layer are deposited using an ion source to assist in deposition; S5, maintaining a constant temperature after plating; S6, cooling and removing the component; S7, repeating steps S1 to S6 to coat the same film system on the second side of the lens.

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

[0008] In the infrared short-wave and medium-wave coating process for zinc selenide substrates according to the present disclosure, the same YF3 / ZnSe / YF3 / ZnSe / YF3 / Al2O3 six-layer film structure is coated on both sides of the zinc selenide substrate, the low-refractive index material YF3 and the high-refractive index material ZnSe are alternately used, the medium-refractive index material Al2O3 is used as the outermost protective layer, and the low-refractive index material YF3 and the high-refractive index material ZnSe are used as the main coating materials. By alternately depositing material layers with different refractive indices, a periodic multilayer structure is formed. When the incident light wave enters the coating layer, reflection and transmission are generated at the interface of each layer, and the reflected light wave between the layers The phase difference will lead to destructive interference of reflected light, while the transmitted light will be enhanced, thus achieving high transmittance for light in a specific wavelength range. The refractive index of ZnSe and YF3 is quite different in the infrared short-wave and medium-wave range, and this difference in refractive index makes them ideal materials for constructing multilayer interference films. Al2O3 has good chemical stability and mechanical strength, which can protect the internal multilayer structure from environmental factors, and also provide additional wear resistance, thereby effectively extending the service life of infrared optical devices using lenses with zinc selenide substrates with the same film structure coated on both sides, and reducing maintenance and replacement costs. In addition, as verified by the test process, the transmittance in the 1.5-5μm band can reach an average of 96.62-96.76% (i.e., it can be used to achieve high transmittance in the 1.5-5μm band, i.e., greater than 96.6%), which significantly improves the optical performance of the lens as an infrared window material and provides more efficient light transmission capabilities for infrared optical systems. Furthermore, the high transmittance and enhanced stability enable the lenses prepared by the coating process to be widely used in high-end infrared optical systems such as infrared thermal imaging and military reconnaissance, providing these fields with better optical performance and broadening the scope of application. In addition, the high transmittance coating reduces energy loss in the optical system, improves signal clarity and the overall efficiency of the system, and improves the overall performance of the system.

[0009] In the infrared shortwave and mediumwave coating process for zinc selenide substrates according to the present disclosure, the same YF3 / ZnSe / YF3 / ZnSe / YF3 / Al2O3 six-layer film structure is coated on both sides of the zinc selenide substrate. The first to fourth film layers are not deposited using an ion source, and the fifth YF3 and sixth Al2O3 film layers are deposited using an ion source. This can enhance the adhesion between the fifth YF3 film layer and the fourth ZnSe film layer and between the fifth YF3 film layer and the sixth Al2O3 film layer and the density of the film layer, thereby improving the stability, optical performance and durability of the film layer in complex environments. By adopting the film layer structure of Sub (zinc selenide substrate) / YF3 / ZnSe / YF3 / ZnSe / YF3 / Al2O3 / Air (air), as verified by the test, it can pass eight tests including friction resistance test, blister test, adhesion test, hot and cold shock test, constant temperature and humidity test, salt spray test, low temperature test and high temperature test, that is, it can be used to achieve acceptance that meets the requirements of friction resistance test, blister test, adhesion test, hot and cold shock test, constant temperature and humidity test, salt spray test, low temperature test and high temperature test. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic structural diagram of a zinc selenide substrate and film systems on both sides prepared by the infrared short-wave and medium-wave coating process for a zinc selenide substrate disclosed in the present invention.

[0011] Figure 2 It is a transmittance curve of the accompanying coating sheet of Example 1 together with the films on both sides in the 1.5-5μm band.

[0012] Figure 3 It is a transmittance curve of the accompanying coating sheet of comparative example 1 together with the films on both sides in the 1.5-5 μm band. DETAILED DESCRIPTION

[0013] It will be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in various forms, and therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to implement the present disclosure in various ways.

[0014] [Infrared short-wave and medium-wave coating process for zinc selenide substrate]

[0015] Reference Figure 1 According to the present disclosure, the infrared short-wave and medium-wave coating process for zinc selenide substrates includes the following steps:

[0016] S1, before plating, clean the accompanying plating sheet and products of the zinc selenide substrate as the lens and prepare the three types of film materials: YF3, ZnSe and Al2O3;

[0017] S2, the cleaned lens is placed in a fixture, and the fixture with the lens is hung in the cavity of the coating machine for vacuum baking and pre-melting of the film material;

[0018] S3, ion source cleaning lens;

[0019] S4, under vacuum conditions, depositing a first YF3 film layer, a second ZnSe film layer, a third YF3 film layer, a fourth ZnSe film layer, a fifth YF3 film layer, and a sixth Al2O3 film layer on the first surface of the lens in sequence, the six film layers forming a film system, the first to fourth film layers are not deposited using an ion source, and the fifth YF3 film layer and the sixth Al2O3 film layer are deposited using an ion source;

[0020] S5, constant temperature maintenance after plating;

[0021] S6, cooling and picking up;

[0022] S7, repeating steps S1 to S6 to coat the second surface of the lens with the same coating system.

[0023] In the infrared short-wave and medium-wave coating process for zinc selenide substrates according to the present disclosure, the same YF3 / ZnSe / YF3 / ZnSe / YF3 / Al2O3 six-layer film structure is coated on both sides of the zinc selenide substrate, the low-refractive index material YF3 and the high-refractive index material ZnSe are alternately used, the medium-refractive index material Al2O3 is used as the outermost protective layer, and the low-refractive index material YF3 and the high-refractive index material ZnSe are used as the main coating materials. By alternately depositing material layers with different refractive indices, a periodic multilayer structure is formed. When the incident light wave enters the coating layer, reflection and transmission are generated at the interface of each layer, and the reflected light wave between the layers The phase difference will lead to destructive interference of reflected light, while the transmitted light will be enhanced, thereby achieving high transmittance for light in a specific wavelength range. The refractive index of ZnSe and YF3 is quite different in the infrared short-wave and medium-wave range, and this difference in refractive index makes them ideal materials for constructing multilayer interference films. Al2O3 has good chemical stability and mechanical strength, which can protect the internal multilayer structure from environmental factors, and also provide additional wear resistance, thereby effectively extending the service life of infrared optical devices using lenses with zinc selenide substrates with the same film structure coated on both sides, and reducing maintenance and replacement costs. In addition, as verified by the test process described later, the transmittance in the 1.5-5μm band can reach an average of 96.62-96.76% (i.e., it can be used to achieve high transmittance in the 1.5-5μm band, i.e., greater than 96.6%), which significantly improves the optical performance of the lens as an infrared window material and provides a more efficient light transmission capability for infrared optical systems. Furthermore, the high transmittance and enhanced stability enable the lenses prepared by the coating process to be widely used in high-end infrared optical systems such as infrared thermal imaging and military reconnaissance, providing these fields with better optical performance and broadening the scope of application. In addition, the high transmittance coating reduces energy loss in the optical system, improves signal clarity and the overall efficiency of the system, and improves the overall performance of the system.

[0024] In the infrared shortwave and mediumwave coating process for zinc selenide substrates according to the present disclosure, the same YF3 / ZnSe / YF3 / ZnSe / YF3 / Al2O3 six-layer film structure is coated on both sides of the zinc selenide substrate. The first to fourth film layers are not deposited using an ion source, and the fifth YF3 and sixth Al2O3 film layers are deposited using an ion source. This can enhance the adhesion between the fifth YF3 film layer and the fourth ZnSe film layer and between the fifth YF3 film layer and the sixth Al2O3 film layer and the density of the film layer, thereby improving the stability, optical performance and durability of the film layer in complex environments. By adopting the film layer structure of Sub (zinc selenide substrate) / YF3 / ZnSe / YF3 / ZnSe / YF3 / Al2O3 / Air (air), as verified by the test, it can pass eight tests including friction resistance test, blister test, adhesion test, hot and cold shock test, constant temperature and humidity test, salt spray test, low temperature test and high temperature test, that is, it can be used to achieve acceptance that meets the requirements of friction resistance test, blister test, adhesion test, hot and cold shock test, constant temperature and humidity test, salt spray test, low temperature test and high temperature test.

[0025] The cleaning in step S1 is beneficial to improving the surface state of the first and second surfaces of the lens, removing surface contaminants, ensuring cleanliness before coating, ensuring that there will be no interference from impurities during the coating process, and helping to improve the bonding performance of the corresponding film system on each surface with the corresponding surface of the lens, and improving the flatness of the film layer. For example, in step S1, ultrasonic cleaning is used for cleaning. Specifically, ultrasonic cleaning uses alumina polishing liquid for polishing, followed by ultrasonic pure water cleaning. For example, the alumina polishing liquid uses a 0.1μm polycrystalline diamond liquid from Nanjing Henry Precision Optics Co., Ltd. For example, the thickness of the accompanying plating sheet is 1.0mm.

[0026] The baking in step S2 is to prepare the temperature for pre-melting of the film material. Pre-melting of the film material can release the gas in the film material and remove the impurities in the film material to ensure the purity of the film material, thereby reducing the adverse factors that affect the quality of the film layer during the film coating process of step S4 repeated in step S7. In addition, baking also heats the lens. In one example, in step S2, the temperature of the chamber of the coating machine is set to 120°C; when the vacuum reaches (3.0-5.0)×10 -3 The film material is pre-melted at 120°C. After the pre-melting of the film material is completed, the temperature of the cavity of the coating machine reaches 120°C and is kept constant for 15-20 minutes. YF3 and ZnSe are pre-melted by resistance heating, and Al2O3 is pre-melted by electron beam heating.

[0027] The ion source cleaning in step S3 effectively purifies and activates the surface of the lens through high-energy ion bombardment, optimizes the surface comprehensive characteristics, and promotes uniform and dense deposition of the film layer, thereby improving the overall performance and long-term stability of the coating. In one example, in step S3, when the vacuum degree reaches 8.0×10 -4 Pa-1.0×10 -3 Pa, start the ion source of the vacuum coating machine. The ion source is a Hall ion source. The ion source parameters are: neutralization current 0.6A, neutralization gas flow rate 8sccm, anode voltage 220V, anode current 2A, argon gas flow rate ratio 100%, and cleaning time 300-400s.

[0028] In one example, in step S4, during the coating process, argon gas is filled into the chamber of the coating machine and evacuated to form a flowing vacuum, ensuring that the vacuum degree of the coating is maintained at (4.5-5.5)×10 -3 Pa, and maintain the coating temperature at 120°C.

[0029] In one example, in step S4, the evaporation mode of the film material is: YF3 and ZnSe are both evaporated using resistance heating, and Al2O3 is evaporated using electron beam.

[0030] In one example, in step S4, the evaporation rate of YF3 is The evaporation rate of ZnSe is The evaporation rate of Al2O3 is

[0031] In one example, in step S4,

[0032] The thickness of the first YF3 film layer is 55.7nm.

[0033] The thickness of the second ZnSe film layer is 146.8nm.

[0034] The thickness of the third YF3 film layer is 165.1nm.

[0035] The thickness of the fourth ZnSe film layer is 69.7nm.

[0036] The thickness of the fifth YF3 film layer is 438.1nm.

[0037] The thickness of the sixth Al2O3 film layer is 30nm;

[0038] In step S4, the film thickness is monitored 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 6 MHz.

[0039] In one example, in step S4, for the fifth YF3 film layer, the ion source is a Hall ion source, and the ion source parameters for auxiliary deposition are: neutralization current 0.6A, neutralization gas flow rate 8sccm, anode voltage 130V, anode current 1.3A, and argon gas flow rate accounting for 100%; for the sixth Al2O3 film layer, the ion source is a Hall ion source, and the ion source parameters for auxiliary deposition are: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 100V, anode current 1A, and argon gas flow rate accounting for 100%.

[0040] In one example, in step S5, after plating is completed, the chamber is kept at a constant temperature of 120°C for 5-15 minutes.

[0041] In one example, in step S6, the door is opened to take out the items when the temperature drops below 100°C.

[0042] [test]

[0043] Example 1

[0044] The infrared short-wave and medium-wave coating process for zinc selenide substrates of Example 1 adopts the following steps:

[0045] S1, before plating, ultrasonic cleaning is used to clean the accompanying plating sheets and products of the zinc selenide substrate of the lens and prepare the three types of film materials, YF3, ZnSe, and Al2O3. The thickness of the accompanying plating sheet is 1.0mm. Ultrasonic cleaning is performed using alumina polishing liquid and then ultrasonic pure water cleaning. The alumina polishing liquid uses a 0.1μm polycrystalline diamond liquid from Nanjing Henry Precision Optics Co., Ltd.;

[0046] S2, the cleaned lens is placed in the fixture, and the fixture with the lens is hung in the cavity of the coating machine, vacuum baking and pre-melting of the film material. The coating machine is a vacuum coating machine with Hall ion source manufactured and sold by Chengdu Xiwok Vacuum Technology Co., Ltd. The temperature of the cavity is set to 120℃. When the vacuum reaches 4.0×10 -3 The film material is pre-melted at Pa. YF3 and ZnSe are pre-melted by resistance heating, and Al2O3 is pre-melted by electron beam heating. After the film material is pre-melted, the temperature of the cavity of the coating machine reaches 120℃ and is kept constant for 20 minutes.

[0047] S3, ion source cleaning lens, when the vacuum reaches 9.0×10 -4 When Pa, the ion source of the vacuum coating machine is started. The ion source is a Hall ion source. The ion source parameters are: neutralization current 0.6A, neutralization gas flow rate 8sccm, anode voltage 220V, anode current 2A, argon gas flow rate ratio 100%, and cleaning time 350s;

[0048] S4, under vacuum conditions, a first YF3 film layer, a second ZnSe film layer, a third YF3 film layer, a fourth ZnSe film layer, a fifth YF3 film layer, and a sixth Al2O3 film layer are deposited on the first surface of the lens in sequence, and the six film layers constitute a film system. The first to fourth film layers are not deposited using an ion source, and the fifth YF3 film layer and the sixth Al2O3 film layer are deposited using an ion source.

[0049] in,

[0050] During coating, argon gas is filled into the chamber of the coating machine and evacuated to form a flowing vacuum to ensure that the vacuum degree of the coating is maintained at 5.0×10 -3 Pa, and maintain the coating temperature at 120°C;

[0051] The evaporation mode of the film materials is: YF3 and ZnSe are evaporated by resistance heating, and Al2O3 is evaporated by electron beam;

[0052] The evaporation rate of YF3 is The evaporation rate of ZnSe is The evaporation rate of Al2O3 is

[0053] The thickness of the first YF3 film layer is 55.7nm.

[0054] The thickness of the second ZnSe film layer is 146.8nm.

[0055] The thickness of the third YF3 film layer is 165.1nm.

[0056] The thickness of the fourth ZnSe film layer is 69.7nm.

[0057] The thickness of the fifth YF3 film layer is 438.1nm.

[0058] The thickness of the sixth Al2O3 film layer is 30nm;

[0059] The crystal oscillator method is used to monitor the film thickness by using the corresponding crystal oscillator of the multiple crystal oscillators of the crystal controller. After the ion source is cleaned, the crystal controller controls the corresponding operation of the new crystal oscillator of the multiple crystal oscillators, and the crystal oscillator frequency is not less than 6MHz.

[0060] For the fifth YF3 film layer, the ion source is a Hall ion source, and the ion source parameters for auxiliary deposition are: neutralization current 0.6A, neutralization gas flow 8sccm, anode voltage 130V, anode current 1.3A, and argon gas flow 100%;

[0061] For the sixth Al2O3 film layer, the ion source is a Hall ion source, and the ion source parameters for auxiliary deposition are: neutralization current 0.5A, neutralization gas flow 8sccm, anode voltage 100V, anode current 1A, and argon gas flow 100%;

[0062] S5, after plating is completed, the cavity is kept at a constant temperature of 120°C for 10 minutes;

[0063] S6, wait until the temperature drops to 80°C, open the door and take out the items;

[0064] S7, repeating steps S1 to S6 to coat the second surface of the lens with the same coating system.

[0065] Example 2

[0066] Except for the vacuum in step S2, the vacuum reaches 3.0×10 -3 Pa, the film material is pre-melted, and in step S3, when the vacuum degree reaches 8.0×10 -4 The ion source of the vacuum coating machine is started at 9000 ℃ Pa and the temperature is kept constant for 5 minutes in step S5, and the rest is the same as in embodiment 1.

[0067] Example 3

[0068] Except for the vacuum in step S2, the vacuum reaches 5.0×10 -3 Pa, the film material is pre-melted, and in step S3, when the vacuum degree reaches 1.0×10 -3 Pa, the ion source of the vacuum coating machine is started and the temperature is kept constant for 15 minutes in step S5, and the rest is the same as in embodiment 1.

[0069] Comparative Example 1

[0070] Except that in step S4, all six film layers are deposited using ion source assisted deposition, the ion source is a Hall ion source when plating the ZnSe film layer, and the ion source parameters are: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 100V, anode current 1A, and argon gas flow rate accounts for 100%, the rest is the same as Example 1.

[0071] Comparative Example 2

[0072] Except that there is no Al2O3 film material in step S1, step S2 does not involve pre-melting of Al2O3 film material, and step S4 does not deposit the sixth Al2O3 film layer (i.e., the Al2O3 film layer is eliminated from the film system on each surface), the rest is the same as Example 1.

[0073] Comparative Example 3

[0074] Except that in step S4, the six film layers are not deposited using ion source assistance, the rest is the same as in Example 1.

[0075] The following tests were performed on Examples 1-3 and Comparative Examples 1-3 after coating on both sides.

[0076] Water bubble test: Take tap water to conduct a water bubble test for 2 hours to observe whether the film layer on each surface falls off from the accompanying plating sheet and whether the film layer on each surface is cracked.

[0077] Adhesion test: Use hand to stick 3M tape on each side of the plating sheet and pull the tape in the direction opposite to the sticking end to observe whether the film layer is pulled up.

[0078] Friction resistance test (moderate friction test): Wrap the rubber friction head of the friction machine with degreased cloth, apply a pressure of 4.9N on the film surface of the accompanying plating sheet and rub it 50 times (25 times back and forth), and observe whether there are signs of scratches or damage on the surface of the film layer.

[0079] Thermal shock test: In a high and low temperature box, perform thermal shock test in the range of -40℃ to 85℃ for 24 hours to observe whether the film layers on each side of the accompanying plating sheet fall off or crack.

[0080] Constant temperature and humidity test: In a constant temperature and humidity chamber, at 50°C and 95% relative humidity for 48 hours, observe whether the film layers on each side of the accompanying plating sheet fall off or crack.

[0081] Salt spray test: neutral salt spray test for 48 hours, observe whether the film layer on each side of the accompanying plating sheet falls off, observe whether the film layer on each side of the accompanying plating sheet cracks.

[0082] Low temperature test: In a low temperature box, at -40℃ for 48h, observe whether the film layers on each side of the accompanying plating sheet fall off, and observe whether the film layers on each side of the accompanying plating sheet crack.

[0083] High temperature test: In a high temperature box, at 85℃ for 48h, observe whether the film layers on each side of the accompanying plating sheet fall off, and observe whether the film layers on each side of the accompanying plating sheet crack.

[0084] Table 1 shows the average transmittance of Examples 1-3 and Comparative Examples 1-3 in the 1.5-5 μm band and the results of various tests.

[0085] Table 1 Average transmittance of Examples 1-3 and Comparative Examples 1-3 in the 1.5-5 μm band and results of various tests

[0086]

[0087] in, Figure 2 It is a transmittance curve of the accompanying coating sheet of Example 1 together with the films on both sides in the 1.5-5μm band. Figure 3 It is a transmittance curve of the accompanying coating sheet of comparative example 1 together with the films on both sides in the 1.5-5 μm band.

[0088] The above detailed description is used to describe multiple exemplary embodiments, 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 simplicity.

Claims

1. An infrared short-wave and medium-wave coating process for a zinc selenide substrate, characterized in that: Includes steps: S1, before plating, clean the accompanying plating sheet and products of the zinc selenide substrate as the lens and prepare the three types of film materials: YF3, ZnSe and Al2O3; S2, the cleaned lens is placed in a fixture, and the fixture with the lens is hung in the cavity of the coating machine for vacuum baking and pre-melting of the film material; S3, ion source cleaning lens; S4, under vacuum conditions, depositing a first YF3 film layer, a second ZnSe film layer, a third YF3 film layer, a fourth ZnSe film layer, a fifth YF3 film layer, and a sixth Al2O3 film layer on the first surface of the lens in sequence, the six film layers forming a film system, the first to fourth film layers are not deposited using an ion source, and the fifth YF3 film layer and the sixth Al2O3 film layer are deposited using an ion source; S5, constant temperature maintenance after plating; S6, cooling and picking up; S7, repeating steps S1 to S6 to coat the second surface of the lens with the same coating system.

2. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: In step S1, ultrasonic cleaning is used for cleaning, and the thickness of the accompanying plating sheet is 1.0 mm; Ultrasonic cleaning uses aluminum oxide polishing liquid for polishing, followed by ultrasonic pure water cleaning. The alumina polishing liquid adopts the 0.1μm polycrystalline diamond liquid produced by Nanjing Henry Precision Optics Co., Ltd.

3. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: In step S2, The temperature of the coating machine chamber is set to 120°C; When the vacuum reaches (3.0-5.0)×10 -3 Pa, the film material is pre-melted. YF3 and ZnSe are pre-melted by resistance heating, and Al2O3 is pre-melted by electron beam heating. After the film material is pre-melted, the temperature of the cavity of the coating machine reaches 120℃ and keeps constant for 15-20 minutes.

4. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: In step S3, When the vacuum degree reaches 8.0×10 -4 Pa-1.0×10 -3 Pa, start the ion source of the vacuum coating machine, The ion source is a Hall ion source, and the ion source parameters are: neutralization current 0.6A, neutralization gas flow rate 8sccm, anode voltage 220V, anode current 2A, argon gas flow rate ratio 100%, and cleaning time 300-400s.

5. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: In step S4, During coating, argon gas is filled into the cavity of the coating machine and evacuated to form a flowing vacuum to ensure that the vacuum degree of the coating is maintained at (4.5-5.5)×10 -3 Pa, and maintain the coating temperature at 120°C.

6. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: In step S4, The evaporation mode of the film material is: YF3 and ZnSe are evaporated by resistance heating, and Al2O3 is evaporated by electron beam.

7. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: In step S4, The evaporation rate of YF3 is The evaporation rate of ZnSe is The evaporation rate of Al2O3 is 8. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: In step S4, The thickness of the first YF3 film layer is 55.7nm. The thickness of the second ZnSe film layer is 146.8nm. The thickness of the third YF3 film layer is 165.1nm. The thickness of the fourth ZnSe film layer is 69.7nm. The thickness of the fifth YF3 film layer is 438.1nm. The thickness of the sixth Al2O3 film layer is 30nm; In step S4, the film thickness is monitored 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 6 MHz.

9. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: For the fifth YF3 film layer, the ion source is a Hall ion source, and the ion source parameters for auxiliary deposition are: neutralization current 0.6A, neutralization gas flow 8sccm, anode voltage 130V, anode current 1.3A, and argon gas flow 100%; For the sixth Al2O3 film layer, the ion source is a Hall ion source, and the ion source parameters for auxiliary deposition are: neutralization current 0.5A, neutralization gas flow rate 8sccm, anode voltage 100V, anode current 1A, and argon gas flow rate 100%.

10. The infrared short-wave and medium-wave coating process for zinc selenide substrate according to claim 1, characterized in that: In step S5, after the plating is completed, the cavity is kept at a constant temperature of 120°C for 5-15 minutes; In step S6, the door is opened to take out the items when the temperature drops below 100°C.

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