Design method and preparation method of high-transparency thin film with thickness of 2-5.5 μm on ZnSe substrate
By designing and fabricating the film structure of ZnSe substrate films, the shortcomings of existing ZnSe substrate films in terms of durability and transmittance were overcome, achieving high transmittance in the 2-5.5μm wavelength range and passing various environmental tests.
Patent Information
- Application Number
- CN202411530072.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2044-10-30
AI Technical Summary
Existing ZnSe substrate 2-5.5μm thin films have high durability requirements in different applications, and existing technologies make it difficult to design and prepare film systems that meet the requirements of low reflection loss, strong signal strength and sensitive detection response.
The film structure was designed using the film stack formula Sub/0.6(LHL)^2MK/AIR, with ZnSe as the high refractive index material, YbF3 as the low refractive index material, Y2O3 as the connecting layer, and Al2O3 as the protective layer. The film thickness was optimized using thin film design software, and the coating process conditions were precisely controlled in the coating machine.
The designed and prepared ZnSe substrate film achieved the required transmittance in the 2-5.5μm wavelength range and passed water immersion, salt spray, adhesion, moderate friction, constant temperature and humidity, low temperature and high temperature tests to meet the durability requirements of different applications.
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Figure CN119471868B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of infrared optical thin film technology, and more specifically to a design method and preparation method for a 2-5.5 μm high-transmittance thin film on a ZnSe substrate. Background Technology
[0002] The 2-5.5μm band is a common application range in mid-infrared radiation. ZnSe substrate antireflective films in this band are widely used in infrared thermometry, thermal imaging, uncooled infrared focal plane array detection, and wafer packaging windows due to their advantages such as low reflection loss, strong signal strength, and sensitive detection response. Furthermore, different applications require high durability of the films, such as stretch film testing, abrasion resistance, and resistance to constant temperature and humidity. Therefore, the selection of coating materials, the design of the film system, and the improvement of the specific coating process increase the difficulty. Summary of the Invention
[0003] In view of the problems existing in the background art, one object of this disclosure is to provide a design method and a preparation method for a ZnSe substrate 2-5.5μm high transmittance film, which can design and prepare a ZnSe substrate and the film system on both sides with the required transmittance in the 2-5.5μm band.
[0004] Another objective of this disclosure is to provide a design method and preparation method for a 2-5.5 μm high-transmittance thin film on a ZnSe substrate, which enables the designed and prepared ZnSe substrate, along with the film system on both sides, to meet the requirements of different applications.
[0005] Therefore, a design method for a 2-5.5μm high-transmittance thin film on a ZnSe substrate includes the following steps: Sa, the film system design uses 550nm as the reference wavelength for optical thin film design, and uses the film stack formula: Sub / 0.6(LHL)^2MK / AIR, where Sub has the same film system deposited on both sides, where Sub is the ZnSe substrate, AIR represents air, and in the film stack expression: H represents 1 / 4 wavelength thickness of the high-refractive-index material ZnSe (zinc selenide), L represents 1 / 4 wavelength thickness of the low-refractive-index material YbF3 (ytterbium fluoride), and K represents 1 / 4 wavelength thickness... The protective layer material is Al2O3 (alumina), and M represents the 1 / 4 wavelength thickness connecting layer material Y2O3 (yttrium oxide); Sb, through the input film stack formula, generates a film structure of Sub / YbF3 / ZnSe / YbF3 / ZnSe / YbF3 / Y2O3 / Al2O3 / Air; Sc, through thin film design software, optimizes the film thickness to obtain the optimal film thickness, and the optimized film structure achieves the target transmittance in the 2-5.5μm wavelength band; Sd, the optimized optimal film thickness is input into the control computer of the coating machine.
[0006] A method for preparing a 2-5.5μm high-transmittance thin film on a ZnSe substrate includes the following steps: S1, cleaning the ZnSe substrate (used as a lens) and the accompanying coating sheet before deposition, and preparing four film materials: YbF3, ZnSe, Y2O3, and Al2O3; S2, configuring the deposition process conditions and process documents, including deposition temperature, pre-deposition base vacuum, film thickness, vapor deposition mode of the film materials, deposition rate of the film materials, and the use and parameters of ion source-assisted deposition. The film thickness is based on the aforementioned 2-5.5μm high-transmittance ZnSe substrate. The optimal film thickness is stored in the control computer of the coating machine as described in the thin film design method; 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, the door is closed, vacuum is drawn and heated; S4, the film material is pre-melted; S5, ion source cleaning; S6, layer deposition and monitoring, the first side of the lens is coated according to the coating process conditions and process document configuration in step S2; S7, constant temperature is maintained after coating; S8, the part is cooled and removed; S9, steps S1 to S8 are repeated to coat the second side of the lens.
[0007] The beneficial effects of this disclosure are as follows.
[0008] In the design method of ZnSe substrate 2-5.5μm high transmittance thin film according to the present disclosure, ZnSe is used as a high refractive index material, YbF3 is used as a low refractive index material and as the bottom layer, Y2O3 is used as the final connecting layer, and Al2O3 is used as the protective layer. Thus, not only can the transmittance of the designed film structure in the 2-5.5μm band meet the requirements, but also the water immersion test, salt spray test, adhesion test, moderate friction test, constant temperature and humidity test, low temperature test and high temperature test are taken into account in the testing process of the film system on both sides, so as to meet the requirements of different applications.
[0009] In the method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to this disclosure, based on steps S1 to S9 and the optimal film thickness stored in the control computer of the coating machine as described in the aforementioned design method for a 2-5.5 μm high-transmittance thin film on a ZnSe substrate, as verified by testing, the prepared ZnSe substrate and the film system on both sides can achieve the required transmittance in the 2-5.5 μm band, and can also meet the requirements of water immersion test, salt spray test, adhesion test, moderate friction test, constant temperature and humidity test, low temperature test and high temperature test, thereby meeting the requirements of different applications. Attached Figure Description
[0010] Figure 1 This is a schematic diagram of the film structure based on the design and preparation method of the ZnSe substrate 2-5.5μm high-transmittance thin film disclosed herein.
[0011] Figure 2 The transmittance curve is designed using the design method of the ZnSe substrate 2-5.5μm high transmittance film in Example 1.
[0012] Figure 3 This is a transmittance curve of the substrate and the film system on both sides after the coating is completed, showing the preparation method of the 2-5.5μm high-transmittance thin film on the ZnSe substrate in Example 1.
[0013] Figure 4 The images show the preparation method of the 2-5.5μm high-transmittance thin film on the ZnSe substrate in Example 1, and the photos of the coated sheet and the film system on both sides before and after the adhesion test after the coating is completed.
[0014] Figure 5 The images show the preparation method of the 2-5.5μm high-transmittance thin film on the ZnSe substrate in Example 1, and the photos of the coated sheet and the film system on both sides before and after the water immersion test after the coating is completed. Detailed Implementation
[0015] It is 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.
[0016] [Design method for 2-5.5μm high-transmittance thin films on ZnSe substrate]
[0017] Reference Figure 1 and Figure 2 The design method for a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to this disclosure includes the following steps:
[0018] Sa, the film system design uses 550nm as the reference wavelength for optical thin film design, and uses the film stack formula: Sub / 0.6(LHL)^2MK / AIR, where Sub has the same film system deposited on both sides, where Sub is a ZnSe substrate and AIR represents air. In the film stack expression:
[0019] H represents ZnSe (zinc selenide), a high-refractive-index material with a thickness of 1 / 4 wavelength.
[0020] L represents YbF3 (ytterbium fluoride), a low-refractive-index material with a thickness of 1 / 4 wavelength.
[0021] K represents Al2O3 (alumina), a protective layer material with a thickness of 1 / 4 wavelength.
[0022] M represents the 1 / 4 wavelength thickness of the bonding layer material Y2O3 (yttrium oxide).
[0023] Sb, through the input membrane stack formula, generates a membrane structure of Sub / YbF3 / ZnSe / YbF3 / ZnSe / YbF3 / Y2O3 / Al2O3 / Air;
[0024] Sc, by optimizing the film thickness using thin film design software, obtains the optimal film thickness. The optimized film structure achieves the target transmittance in the 2-5.5μm wavelength range.
[0025] Sd inputs the optimized film thickness into the control computer of the coating machine.
[0026] In the design method of the ZnSe substrate 2-5.5μm high transmittance thin film according to the present disclosure, ZnSe is used as a high refractive index material, YbF3 is used as a low refractive index material and as the bottom layer, Y2O3 is used as the final connecting layer, and Al2O3 is used as the protective layer. Thus, not only can the transmittance of the designed film structure in the 2-5.5μm band meet the requirements, but also the water immersion test, salt spray test, adhesion test, moderate friction test, constant temperature and humidity test, low temperature test and high temperature test are taken into account in the test process of the film system on both sides, thereby meeting the requirements of different applications.
[0027] In one example, in step Sc, for each of the two surfaces of the lens, the optimal film thickness is expressed in terms of film structure as follows:
[0028] Sub / YbF3(38.73) / ZnSe(214.84) / YbF3(150.86) / ZnSe(108.41) / YbF3(520.68) / Y2O3(15) / Al2O3(30) / Air, where the numbers in parentheses represent the film thickness in nm.
[0029] In one example, in step Sc, the average transmittance of the optimized ZnSe substrate in the 2–5.5 μm band is greater than 98%.
[0030] In one example, in steps Sa to Sd, the software is designed as TFCalc or Essential Macleod.
[0031] [Preparation method of 2-5.5μm high-transmittance thin film on ZnSe substrate]
[0032] The method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to this disclosure includes the following steps:
[0033] S1, cleaning of the ZnSe substrate used as the lens and the accompanying coating before plating, and preparation of four types of film materials: YbF3, ZnSe, Y2O3 and Al2O3.
[0034] S2, Configuration of coating process conditions and process documents, including coating temperature, pre-coating base vacuum, film thickness, vapor deposition mode of film material, deposition rate of film material, use and parameters of ion source assisted deposition, wherein the film thickness is based on the optimal film thickness stored in the control computer of the coating machine as described in the aforementioned design method for 2-5.5μm high-transparency thin films on ZnSe substrate;
[0035] S3, the cleaned lenses are placed into the tooling fixture, the tooling fixture with the lenses is hung into the cavity of the coating machine, the door is closed, vacuum is drawn and heating is performed;
[0036] S4, pre-melting of film material;
[0037] S5, Ion source cleaning;
[0038] S6, Coating and Monitoring: Coating is performed on the first surface of the lens according to the coating process conditions and process document configuration in step S2.
[0039] S7, maintain constant temperature after coating is completed;
[0040] S8, cooling down before picking up the item;
[0041] S9. Repeat steps S1 to S8 to apply a coating to the second surface of the lens.
[0042] In the method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to this disclosure, based on steps S1 to S9 and the optimal film thickness stored in the control computer of the coating machine as described in the aforementioned design method for a 2-5.5 μm high-transmittance thin film on a ZnSe substrate, as verified by subsequent tests, the prepared ZnSe substrate, together with the film system on both sides, can achieve the required transmittance in the 2-5.5 μm band. Simultaneously, it can meet the requirements of water immersion tests, salt spray tests, adhesion tests, moderate friction tests, constant temperature and humidity tests, low temperature tests, and high temperature tests, thereby satisfying the requirements of different applications.
[0043] In one example, in step S1, the product is a (50±0.1)mm×(10±0.1)mm disc, and the accompanying plate is a (25±0.1)mm×(2±0.1)mm disc.
[0044] The cleaning in step S1 ensures a clean lens surface, which is beneficial for the adhesion and bonding of the coating. In one example, the lens is polished with an alumina polishing slurry, followed by ultrasonic cleaning with pure water. Specifically, the alumina polishing slurry used is a 0.1μm polycrystalline diamond slurry from Nanjing Hengrui Precision Optics Co., Ltd.
[0045] In one example, in step S2, the coating temperature is 150°C; the pre-coating base vacuum is 1.5 × 10⁻⁶.-3 Pa; the film thickness in the coating process conditions and process documentation configuration is based on the optimal film thickness stored in the control computer of the coating machine as described in the aforementioned design method for 2-5.5 μm high-transparency thin films on ZnSe substrates; the evaporation mode of the film materials is: ZnSe and YbF3 are evaporated using resistance heating, and Y2O3 and Al2O3 are evaporated using electron beam heating; the deposition rate of the film materials is: the deposition rate of the ZnSe film is... The deposition rate of the YbF3 film is: The deposition rate of the Y2O3 film is The deposition rate of the Al2O3 film is The use of ion source-assisted deposition involves turning on the ion source for all film layers. The role of the ion source in ion source-assisted deposition is to solidify the film layers and reduce internal stress. Specifically, in step S2, an APS ion source is used for ion source-assisted deposition. The parameters of the APS ion source are: ion source voltage of 700±50V, ion source current of 700±50mA, accelerating voltage of 500±50V, accelerating current of 700±50mA, pure argon gas as the ion source, argon gas flow rate of 60±5sccm, and argon gas flow rate of 8±0.13sccm in the neutralizer.
[0046] In one example, in step S2, the coating machine is a Guangchi OTFC1300.
[0047] In one example, in step S3, a vacuum is first drawn to 5 × 10⁻⁶. -2 Pa, then the cavity of the coating machine is heated to 150±5℃, and then maintained for 40 minutes.
[0048] In step S4, the pre-melted membrane material undergoes degassing and impurity removal to ensure its purity. In one example, in step S4, when the vacuum reaches (5.0-3.0)×10⁻¹⁰... -3 At step Pa, all ZnSe, YbF3, Y2O3, and Al2O3 films undergo pre-melting treatment. After pre-melting, the temperature of the coating machine cavity reaches 150±5℃ and is maintained at this constant temperature for 10 minutes. Specifically, in step S4, the pre-melting treatment employs both electron beam heating and resistance heating. For ZnSe films, the resistance heating current is 720-760 mA; for YbF3 films, the resistance heating current is 860-900 mA; for Y2O3 films, the electron beam heating current is 150-210 mA; and for Al2O3 films, the electron beam heating current is 260-290 mA.
[0049] The ion source cleaning in step S5 utilizes ion bombardment to remove the oxide layer and impurities from the wafer surface, resulting in a cleaner surface and increased film adhesion. In one example, in step S5, a vacuum is drawn to achieve a vacuum level of (1.5 ± 0.1) × 10⁻⁶. -3 Pa, start the ion source to perform ion cleaning on the lens. The ion source is an APS ion source. The parameters of the APS ion source are: ion source voltage 700±50V, ion source current 700±50mA, accelerating voltage 500±50V, accelerating current 700±50mA, pure argon gas is used for the ion source, the argon gas flow rate of the ion source is 60±5sccm, the argon gas flow rate of the neutralizer is 8±0.13sccm, and the cleaning time is 60s.
[0050] In one example, in step S6, when depositing each film layer, no gas is introduced from outside the coating machine into the cavity of the coating machine, and the cavity of the coating machine is kept evacuated and the coating temperature is kept at 150±5℃; each film layer is deposited at a temperature of 150℃ in the cavity of the coating machine; the film thickness is monitored by using the crystal oscillator method with the corresponding crystal oscillators of multiple crystal oscillators of the crystal controller; after ion source cleaning, 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 5850Hz.
[0051] In one example, in step S7, after the plating is completed, the cavity is kept at 150°C for 30 minutes.
[0052] In one example, in step S8, after step S7 is completed, the temperature is first lowered to 120°C at 1°C / min and held for 5 minutes, then lowered to 90°C at 1°C / min and held for 5 minutes, and then lowered to below 60°C at 1°C / min before the door is opened and the item is taken out.
[0053] [test]
[0054] Example 1
[0055] Part 1: Design Methods for 2-5.5μm High-Transparency Thin Films on ZnSe Substrates
[0056] The design method for 2-5.5μm high-transmittance thin films on ZnSe substrates adopts the following steps:
[0057] Sa, the film system design uses 550nm as the reference wavelength for optical thin film design. In TFCalc, the film stack formula is used: Sub / 0.6(LHL)^2MK / AIR, where Sub has the same film system deposited on both sides, and Sub is a ZnSe substrate, and AIR represents air. In the film stack expression:
[0058] H represents ZnSe (zinc selenide), a high-refractive-index material with a thickness of 1 / 4 wavelength.
[0059] L represents YbF3 (ytterbium fluoride), a low-refractive-index material with a thickness of 1 / 4 wavelength.
[0060] K represents Al2O3 (alumina), a protective layer material with a thickness of 1 / 4 wavelength.
[0061] M represents the 1 / 4 wavelength thickness of the bonding layer material Y2O3 (yttrium oxide).
[0062] Sb, through the input membrane stack formula, generates a membrane structure of Sub / YbF3 / ZnSe / YbF3 / ZnSe / YbF3 / Y2O3 / Al2O3 / Air;
[0063] The film thickness was optimized using the thin film design software TFCalc to obtain the optimal film thickness. The optimized film structure achieved the target transmittance in the 2-5.5 μm wavelength range.
[0064] In step Sc, for each of the two sides of the lens, the optimal coating thickness is determined by the film thickness.
[0065] The layer structure is represented as:
[0066] Sub / YbF3(38.73) / ZnSe(214.84) / YbF3(150.86) / ZnSe(108.41) / YbF3(520.
[0067] 68) / Y2O3(15) / Al2O3(30) / Air, where the numbers in parentheses represent the film thickness, and the film thickness is expressed as a single unit.
[0068] The position is nm;
[0069] Sd inputs the optimized film thickness into the control computer of the coating machine, which is a Guangchi OTFC1300.
[0070] Part 2: Preparation method of 2-5.5μm high-transmittance thin films on ZnSe substrate
[0071] The preparation method of ZnSe substrate 2-5.5μm high-transmittance thin film adopts the following steps:
[0072] S1, cleaning of the ZnSe substrate and the accompanying coating before plating, and preparation of four types of film materials: YbF3, ZnSe, Y2O3 and Al2O3. The product is a 50mm×10mm disc, and the accompanying coating is a 25mm×2mm disc. The lens is polished with an alumina polishing slurry and then ultrasonically cleaned with pure water. The alumina polishing slurry used is 0.1μm polycrystalline diamond slurry from Nanjing Hengrui Precision Optics Co., Ltd.
[0073] S2, Configuration of coating process conditions and process documents. The configuration of coating process conditions and process documents includes coating temperature, pre-coating base vacuum, film thickness, vapor deposition mode of the film material, deposition rate of the film material, and the use and parameters of ion source-assisted deposition. The film thickness is based on the optimal film thickness stored in the control computer of the coating machine as described in the design method for 2-5.5μm high-transparency thin films on ZnSe substrates in Part I.
[0074] In step S2,
[0075] The coating temperature is 150℃;
[0076] The base vacuum before plating is 1.5 × 10⁻⁶. -3 Pa;
[0077] The film thickness in the coating process conditions and process document configuration is based on the optimal film thickness stored in the control computer of the coating machine as described in the design method of 2-5.5μm high-transparency thin film on ZnSe substrate in Part 1;
[0078] The deposition methods for the film materials are as follows: ZnSe and YbF3 are evaporated using resistance heating, while Y2O3 and Al2O3 are evaporated using resistance heating.
[0079] Evaporation using electron beam heating;
[0080] The deposition rate of the film material is: the deposition rate of the ZnSe film layer is The deposition rate of the YbF3 film is: The deposition rate of the Y2O3 film is The deposition rate of the Al2O3 film is
[0081]
[0082] The use of ion source-assisted deposition involves turning on the ion source for all film layers;
[0083] Ion source assisted deposition uses an APS ion source with the following parameters: ion source voltage of 700V, ion source current of 700mA, accelerating voltage of 500V, accelerating current of 700mA, pure argon gas for the ion source, argon gas flow rate of 60sccm, and argon gas flow rate of 8sccm for the neutralizer.
[0084] S3. Place the cleaned lenses into the fixture, hang the fixture with the lenses in it into the cavity of the coating machine, close the door, and first evacuate to 5×10. -2 Pa, then the cavity of the coating machine is heated to 150°C and then maintained for 40 minutes;
[0085] S4, pre-melting of the film material, when the vacuum reaches 5.0×10 -3At step Pa, all ZnSe, YbF3, Y2O3, and Al2O3 film materials were pre-melted. After pre-melting, the temperature of the coating machine cavity reached 150℃ and was maintained at a constant temperature for 10 minutes.
[0086] In step S4, the pre-melting process employs both electron beam heating and resistance heating.
[0087] For ZnSe film material, the resistance heating current is 740mA;
[0088] For YbF3 film material, the resistance heating current is 880mA.
[0089] For Y2O3 film material, the electron beam heating current is 180mA;
[0090] For Al2O3 film material, the electron beam heating current is 275mA;
[0091] S5, Ion source cleaning, vacuuming to achieve a vacuum level of 1.5 × 10⁻⁶ in the chamber. -3 Pa, start the ion source to perform ion cleaning on the lens. The ion source is an APS ion source. The parameters of the APS ion source are: ion source voltage is 700V, ion source current is 700mA, acceleration voltage is 500V, acceleration current is 700mA, the ion source uses pure argon gas, the argon gas flow rate of the ion source is 60sccm, the argon gas flow rate of the neutralizer is 8sccm, and the cleaning time is 60s.
[0092] S6, Coating and Monitoring: Following the coating process conditions and process documentation from step S2, a coating layer is applied to the first surface of the lens.
[0093] In step S6,
[0094] When depositing each film layer, no gas is introduced from outside the coating machine into the cavity of the coating machine, and the cavity of the coating machine is kept evacuated while maintaining the coating temperature at 150°C.
[0095] Each film layer is deposited at a temperature of 150°C in the cavity of the coating machine;
[0096] The crystal oscillator method uses multiple crystal oscillators of a crystal controller to monitor film thickness. After ion source cleaning, the crystal controller controls a new crystal oscillator among the multiple crystal oscillators to operate accordingly.
[0097] The vibration frequency is 5990Hz;
[0098] S7, after plating, keep the cavity at 150℃ for 30 minutes;
[0099] S8. After step S7 is completed, first cool down to 120℃ at 1℃ / min and hold for 5min, then cool down to 90℃ at 1℃ / min and hold for 5min, then cool down to 60℃ at 1℃ / min and open the door to take out the part.
[0100] S9. Repeat steps S1 to S8 to apply a coating to the second surface of the lens.
[0101] Comparative Example 1
[0102] Except for step S5, where the ion source voltage is 500V, the ion source current is 500mA, and the accelerating current is 300mA, the rest is the same as in Example 1.
[0103] Comparative Example 2
[0104] Except for step S5, in which the ion source is a mixture of argon and oxygen, the argon flow rate is 10 sccm, and the oxygen flow rate is 50 sccm, the rest is the same as in Example 1.
[0105] Comparative Example 3
[0106] Except for the deposition rate of the Al2O3 film in step S2, which is Except for the above, the rest is the same as in Example 1.
[0107] Comparative Example 4
[0108] Except that in steps S1, S2, and S4, IDA (the IDA film material is commercially available from Umicore, USA, grade 0484519, 0.7-3.5 mm diameter Ida (Ti-Pr-Oxide) particles) is used instead of Y2O3, and in step S2, IDA is evaporated using electron beam heating, and the deposition rate of the IDA film is... In step S4, the electron beam heating current for the needle IDA film material is 450mA, and the rest is the same as in Example 1.
[0109] Comparative Example 5
[0110] Except for replacing Al2O3 with YbF3 in steps S1, S2 and S4, the rest is the same as in Example 1.
[0111] Figure 2 This is a transmittance curve designed using the ZnSe substrate 2-5.5μm high-transmittance film design method of Example 1. Based on Figure 2 The average transmittance of the ZnSe substrate, along with the films on both sides, in the 2-5.5 μm wavelength range is 98.5%.
[0112] Figure 3This is a transmittance curve of the substrate and the film system on both sides after the coating of the ZnSe substrate 2-5.5μm high-transmittance film prepared in Example 1 is completed. Figure 3 The average transmittance of the coated sheet and the film system on both sides is 97.2%.
[0113] The following overall performance tests were conducted on the substrates of Examples 1 and Comparative Examples 1-5, along with the film systems on both sides.
[0114] Water immersion test: Take tap water and conduct a water immersion test for 2 hours, and observe whether the film layer on each surface is peeled off or whether the film layer on each surface is cracked.
[0115] Salt spray test: Neutral salt spray test for 24 hours, observe whether the film layer on each surface peels off or cracks.
[0116] Adhesion test: Apply 3M tape by hand and pull the tape in the opposite direction to the adhesive end on each side to observe whether the film layer is pulled up.
[0117] Moderate friction test: The membrane layer is subjected to 50 rubs with a rubber friction head wrapped with degreased cloth at a pressure of 4.9N, and the presence of scratches or damage is observed.
[0118] Constant temperature and humidity test: In a constant temperature and humidity chamber, at 50℃ and 95% relative humidity for 24 hours, observe whether the film layer on each surface peels off or cracks.
[0119] Low temperature test: In a low temperature chamber, at -40℃ for 24 hours, observe whether the film layer on each surface peels off or cracks.
[0120] High temperature test: In a high temperature chamber, at 85℃ for 24 hours, observe whether the film layer on each surface peels off or cracks.
[0121] Figure 4 The images show the preparation method of the 2-5.5μm high-transparency thin film on the ZnSe substrate in Example 1, and the photos of the coated sheet before and after the adhesion test after the coating is completed.
[0122] Figure 5 The images show the preparation method of the 2-5.5 μm high-transmittance thin film on the ZnSe substrate in Example 1, and the accompanying film and the film system on both sides before and after the water immersion test after the coating is completed.
[0123] Table 1 shows the average transmittance of Example 1 and Comparative Examples 1-5, as well as the results of various tests.
[0124] Table 1 shows the average transmittance of Example 1 and Comparative Examples 1-5, as well as the results of various tests.
[0125]
[0126] 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 2-5.5 μm high-transmittance thin film on a ZnSe substrate, characterized in that, Including the following steps: Sa, the film system design uses 550nm as the reference wavelength for optical thin film design, and uses the film stack formula: Sub / 0.6(LHL)^2MK / AIR, where Sub has the same film system deposited on both sides, where Sub is a ZnSe substrate and AIR represents air. In the film stack expression: H represents ZnSe (zinc selenide), 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. K represents Al2O3 (alumina), a protective layer material with a thickness of 1 / 4 wavelength. M represents the 1 / 4 wavelength thickness of the bonding layer material Y2O3 (yttrium oxide). Sb, through the input membrane stack formula, generates a membrane structure of Sub / YbF3 / ZnSe / YbF3 / ZnSe / YbF3 / Y2O3 / Al2O3 / Air; Sc, by optimizing the film thickness using thin film design software, obtains the optimal film thickness. The optimized film structure achieves the target transmittance in the 2-5.5μm wavelength range. Sd inputs the optimized film thickness into the control computer of the coating machine; In step Sc, for each of the two surfaces of the lens, the optimal coating thickness is expressed in terms of the coating structure as follows: Sub / YbF3(38.73) / ZnSe(214.84) / YbF3(150.86) / ZnSe(108.41) / YbF3(520.68) / Y2O3(15) / Al2O3(30) / Air, where the numbers in parentheses represent the film thickness in nm. In step Sc, the average transmittance of the optimized ZnSe substrate in the 2-5.5 μm band is greater than 98%.
2. A method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate, characterized in that, Including the following steps: S1, cleaning of the ZnSe substrate used as the lens and the accompanying coating before plating, and preparation of four types of film materials: YbF3, ZnSe, Y2O3 and Al2O3. S2, Configuration of coating process conditions and process documents, including coating temperature, pre-coating base vacuum, film thickness, vapor deposition mode of film material, deposition rate of film material, use and parameters of ion source assisted deposition, wherein the film thickness is the optimal film thickness stored in the control computer of the coating machine based on the design method of ZnSe substrate 2-5.5μm high-transparency thin film according to claim 1. S3, the cleaned lenses are placed into the tooling fixture, the tooling fixture with the lenses is hung into the cavity of the coating machine, the door is closed, vacuum is drawn and heating is performed; S4, pre-melting of film material; S5, Ion source cleaning; S6, Coating and Monitoring: Coating is performed on the first surface of the lens according to the coating process conditions and process document configuration in step S2. S7, maintain constant temperature after coating is completed; S8, cooling down before picking up the item; S9. Repeat steps S1 to S8 to apply a coating to the second surface of the lens. The performance testing of the coated sheet and the film system on both sides simultaneously meets the requirements of water immersion test, salt spray test, adhesion test, moderate friction test, constant temperature and humidity test, low temperature test and high temperature test; Water immersion test: Take tap water and conduct a water immersion test for 2 hours, and observe whether the film layer on each surface is peeled off or cracked. Salt spray test: Neutral salt spray test for 24 hours, observe whether the film layer on each surface peels off or cracks. Adhesion test: Apply 3M tape by hand and pull the tape in the opposite direction to the adhesive end on each side, and observe whether the film layer is pulled up; Medium friction test: The membrane layer is subjected to 50 rubs with a rubber friction head wrapped with degreased cloth at a pressure of 4.9N, and the presence of scratches or damage is observed. Constant temperature and humidity test: In a constant temperature and humidity chamber, at 50℃ and 95% relative humidity for 24 hours, observe whether the film layer on each surface peels off or cracks. Low temperature test: In a low temperature chamber, at -40℃ for 24 hours, observe whether the film layer on each surface peels off or cracks. High temperature test: In a high temperature chamber, at 85℃ for 24 hours, observe whether the film layer on each surface peels off or cracks.
3. The method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to claim 2, characterized in that, In step S1, The product is a (50±0.1)mm×(10±0.1)mm round piece, and the accompanying plate is a (25±0.1)mm×(2±0.1)mm round piece; The lenses are polished with aluminum oxide polishing solution and then ultrasonically cleaned with pure water. The alumina polishing slurry used is the 0.1μm polycrystalline diamond slurry from Nanjing Hengrui Precision Optics Co., Ltd.
4. The method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to claim 2, characterized in that, In step S2, The coating temperature is 150℃; The base vacuum before plating is 1.5 × 10⁻⁶. -3 Pa; Film thickness in coating process conditions and process documentation configuration The optimal film thickness is stored in the control computer of the coating machine based on the design method of the ZnSe substrate 2-5.5μm high-transparency thin film according to the claim. The evaporation mode of the film materials is as follows: ZnSe and YbF3 are evaporated by resistance heating, and Y2O3 and Al2O3 are evaporated by electron beam heating. The deposition rate of the film material is: the deposition rate of the ZnSe film layer is The deposition rate of the YbF3 film is: The deposition rate of the Y2O3 film is The deposition rate of the Al2O3 film is The use of ion source-assisted deposition involves turning on the ion source for all film layers; Ion source assisted deposition uses an APS ion source with the following parameters: ion source voltage of 700±50V, ion source current of 700±50mA, accelerating voltage of 500±50V, accelerating current of 700±50mA, pure argon gas as the ion source, argon gas flow rate of 60±5sccm, and argon gas flow rate of 8±0.13sccm in the neutralizer. The coating machine is a Guangchi OTFC1300.
5. The method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to claim 2, characterized in that, In step S3, a vacuum is first drawn to 5×10⁻⁶. -2 Pa, then the cavity of the coating machine is heated to 150±5℃, and then maintained for 40 minutes.
6. The method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to claim 2, characterized in that, In step S4, when the vacuum reaches (5.0-3.0)×10 -3 At Pa, all the film materials ZnSe, YbF3, Y2O3 and Al2O3 are pre-melted. After the film materials are pre-melted, the temperature of the cavity of the coating machine reaches 150±5℃ and is kept constant for 10 minutes. In step S4, the pre-melting process employs both electron beam heating and resistance heating. For ZnSe film material, the resistance heating current is 720-760mA; For YbF3 film material, the resistance heating current is 860-900mA; For Y2O3 film material, the electron beam heating current is 150-210mA; For Al2O3 film material, the electron beam heating current is 260-290mA.
7. The method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to claim 2, characterized in that, In step S5, a vacuum is drawn to bring the vacuum level of the cavity to (1.5 ± 0.1) × 10⁻⁶. -3 Pa, start the ion source to perform ion cleaning on the lens. The ion source is an APS ion source. The parameters of the APS ion source are: ion source voltage 700±50V, ion source current 700±50mA, accelerating voltage 500±50V, accelerating current 700±50mA, pure argon gas is used for the ion source, the argon gas flow rate of the ion source is 60±5sccm, the argon gas flow rate of the neutralizer is 8±0.13scc, and the cleaning time is 60s.
8. The method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to claim 2, characterized in that, In step S6, When depositing each film layer, no gas is introduced from outside the coating machine into the cavity of the coating machine, and the cavity of the coating machine is kept evacuated while maintaining the coating temperature at 150±5℃. Each film layer is deposited at a temperature of 150°C in the cavity of the coating machine; The crystal oscillator method is used to monitor the film thickness by using 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, and the crystal oscillator frequency is not less than 5850Hz.
9. The method for preparing a 2-5.5 μm high-transmittance thin film on a ZnSe substrate according to claim 2, characterized in that, In step S7, after the plating is completed, the cavity is kept at 150°C for 30 minutes; In step S8, after step S7 is completed, the temperature is first lowered to 120℃ at 1℃ / min and held for 5 minutes, then lowered to 90℃ at 1℃ / min and held for 5 minutes, and then lowered to below 60℃ at 1℃ / min before the door is opened and the part is taken out.