Preparation method of 2-2.3 [mu] m short-wave low-reflection film system with germanium substrate

Abstract

The invention discloses a preparation method of a germanium substrate 2-2.3 [mu] m short-wave low-reflection film system. The preparation method comprises the following steps: S1, cleaning accompanying plating sheets of a germanium substrate serving as a lens and a product, wherein the accompanying plating sheets are round sheets and wedge-shaped sheets; s2, loading the lens into a tool clamp, and hanging the tool clamp into the cavity; s3, vacuumizing and cleaning the Hall ion source; s4, on the first surface of the lens, each film layer is plated according to the sequence of 34.8 nm SiO / 64.3 nm Ge / 52.2 nm ZnS / 272.8 nm SiO, the SiO film layer and the Ge film layer are subjected to electron beam heating evaporation, the ZnS film layer is subjected to resistance heating evaporation, the deposition rate of the SiO film layer is 0.6 nm / s, the deposition rate of the Ge film layer is 0.3 nm / s, the deposition rate of the ZnS film layer is 0.8 nm / s, and ion source auxiliary deposition is carried out; s5, the cavity is cooled, and the tool clamp and the lens are taken out; and S6, the step S1 to the step S5 are repeated, the second face of the lens is plated with the same film system, the wedge-shaped piece is not cleaned when the step S1 is repeated, and the wedge-shaped piece is not placed into the tool clamp when the step S2 is repeated.

Description

Technical Field

[0001] The present disclosure relates to the field of infrared coating, and more specifically to a method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate. Background Art

[0002] In the field of infrared optical coating, germanium has good infrared transmittance and refractive index, so it is often used to manufacture infrared optical lenses, infrared cameras, infrared telescopes, infrared sensors and other equipment, and is widely used in infrared imaging systems. However, developing a film system that can have low reflection at short waves of 2-2.3μm is crucial to improving the performance of products using germanium substrates. In addition, improving the adaptability of products using germanium substrates to various environments is also an important development direction. Summary of the invention

[0003] In view of the problems existing in the background technology, an object of the present disclosure is to provide a method for preparing a 2-2.3μm short-wave low-reflection film system on a germanium substrate, wherein the prepared germanium substrate together with the film systems on both sides can be used to improve the surface reflectivity of 2-2.3μm short waves.

[0004] Another object of the present disclosure is to provide a method for preparing a 2-2.3μm short-wave low-reflection film system on a germanium substrate, wherein the prepared germanium substrate together with the film systems on both sides can pass a total of eight tests including a blister test, a salt spray test, an adhesion test, a hot and cold shock test, a constant temperature and humidity test, a friction resistance test, a low temperature test, and a high temperature test, thereby improving the various environmental adaptability performances of products after coating on both sides of the germanium substrate.

[0005] Thus, a method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate comprises the following steps: S1, cleaning the surfaces of the accompanying coating sheet and the product of the germanium substrate as the lens, wherein the accompanying coating sheet is a round sheet of equal thickness and a wedge-shaped sheet with a polished plane on the first surface and a rough rough surface on the second surface; S2, loading the processed lens into a fixture, and hanging the fixture with the lens loaded into the cavity of a vacuum coating machine, and setting the temperature of the cavity to 150°C; S3, starting the vacuum coating machine to evacuate, and the vacuum degree reaches 1.0×10 -3Pa, turn on the Hall ion source of the vacuum coating machine for cleaning, the cleaning time is 6 minutes, the parameters of the Hall ion source are: anode voltage is 220V, anode current is 1.2A, neutralization current is 1.5A, neutralization gas flow rate is 10sccm, and argon gas flow rate is 100%; S4, on the first side of the lens, according to the four-layer film system composed of three film materials of SiO, Ge and ZnS: 34.8nmSiO / 64.3nmGe / 52.2nmZn S / 272.8nmSiO, sequentially plate each film layer, wherein the number with nm before SiO, Ge and ZnS is the film thickness of the corresponding film layer, the SiO film layer and the Ge film layer are evaporated by electron beam heating, the ZnS film layer is evaporated by resistance heating, the deposition rate of the SiO film layer is 0.6nm / s, the deposition rate of the Ge film layer is 0.3nm / s, and the deposition rate of the ZnS film layer is 0.8nm / s, and each film layer is deposited by ion source assistance, and each film layer is deposited at a chamber temperature of 150°C; S5, after the film system is plated on the first side of the lens, the chamber is naturally cooled to below 60°C, and the fixture is taken out together with the lens; S6, repeat steps S1 to S5, and plate the same film system on the second side of the lens, wherein the wedge is not cleaned when repeating step S1 and the fixture is not placed when repeating step S2.

[0006] The beneficial effects of the present disclosure are as follows: In the method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to the present disclosure, the same Sub (germanium substrate) / SiO / Ge / ZnS / SiO / Air (air) film system is plated on both sides of the germanium substrate through steps S1 to S6. Among the three film materials of SiO, Ge and ZnS, SiO has two film layers, Ge and ZnS each have one film layer, the two SiO film layers are used as the base and as the outer surface, respectively, and the Ge film layer and the ZnS film layer are located between the two SiO film layers. The prepared germanium substrate together with the film system on both sides can be used to improve the surface reflectivity of 2-2.3 μm short waves. As verified by the test process, the prepared germanium substrate together with the film system on both sides can pass a total of eight tests including a bubble test, a salt spray test, an adhesion test, a cold and hot shock test, a constant temperature and humidity test, a friction test, a low temperature test, and a high temperature test, thereby being able to improve the various environmental adaptability of the product after the germanium substrate is plated on both sides. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic structural diagram of a germanium substrate and the film systems on both sides prepared according to the method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate disclosed in the present invention.

[0008] Figure 2 This is a photo of the wedge-shaped piece in the accompanying plating film.

[0009] Figure 3It is a curve diagram of the reflectivity of the wedge-shaped plate in the accompanying plating plate of Example 1 together with the film system corresponding to the first surface. DETAILED DESCRIPTION

[0010] The accompanying drawings show embodiments of the present disclosure, and it will be understood that the disclosed embodiments are merely examples of the present disclosure, and the present disclosure can be implemented in various forms. Therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as the basis for the claims and as a representative basis for teaching ordinary technicians in the field to implement the present disclosure in various ways.

[0011] [Preparation method of 2-2.3μm short-wave low-reflection film system on germanium substrate]

[0012] Reference Figure 1 According to the present disclosure, the method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate comprises the following steps:

[0013] S1, cleaning the surfaces of the accompanying plating sheet and the product as the germanium substrate of the lens, wherein the accompanying plating sheet is a round sheet of equal thickness and a wedge-shaped sheet (such as Figure 2 shown);

[0014] S2, loading the processed lens into a fixture, and hanging the fixture with the lens into the vacuum coating machine cavity, and setting the cavity temperature to 150°C;

[0015] S3, vacuum coating machine starts to evacuate, and the vacuum degree reaches 1.0×10 -3 Pa, turn on the Hall ion source of the vacuum coating machine for cleaning, the cleaning time is 6 minutes, the parameters of the Hall ion source are: anode voltage is 220V, anode current is 1.2A, neutralization current is 1.5A, neutralization gas flow rate is 10sccm, and argon gas flow rate is 100%;

[0016] S4, on the first side of the lens, a four-layer film system consisting of three film materials: SiO, Ge and ZnS

[0017] 34.8nmSiO / 64.3nmGe / 52.2nmZnS / 272.8nmSiO, sequentially deposit each film layer,

[0018] The numbers with nm before SiO, Ge and ZnS are the film thicknesses of the corresponding film layers. The SiO film layer and the Ge film layer are evaporated by electron beam heating, and the ZnS film layer is evaporated by resistance heating. The deposition rate of the SiO film layer is 0.6 nm / s, the deposition rate of the Ge film layer is 0.3 nm / s, and the deposition rate of the ZnS film layer is 0.8 nm / s. Each film layer is deposited by ion source assistance, and each film layer is deposited at a chamber temperature of 150°C.

[0019] S5, after the coating system on the first side of the lens is completed, the cavity is naturally cooled to below 60°C, and the fixture and the lens are taken out;

[0020] S6, repeating steps S1 to S5, coating the second surface of the lens with the same film system, wherein the wedge is not cleaned when step S1 is repeated and is not placed in a fixture when step S2 is repeated.

[0021] In the method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to the present disclosure, the same Sub (germanium substrate) / SiO / Ge / ZnS / SiO / Air (air) film system is plated on both sides of the germanium substrate through steps S1 to S6. Among the three film materials of SiO, Ge and ZnS, SiO has two film layers, Ge and ZnS each have one film layer, the two SiO film layers are used as the base and as the outer surface, and the Ge film layer and the ZnS film layer are located between the two SiO film layers. The prepared germanium substrate together with the film system on both sides can be used to improve the surface reflectivity of 2-2.3 μm short waves. As verified by the test process, the prepared germanium substrate together with the film system on both sides can pass a total of eight tests including a bubble test, a salt spray test, an adhesion test, a cold and hot shock test, a constant temperature and humidity test, a friction test, a low temperature test, and a high temperature test, thereby improving the various environmental adaptability of the product after the germanium substrate is plated on both sides.

[0022] The cleaning in step S1 is beneficial to improving the surface state of each surface of the lens, and is helpful to improve the bonding performance of the film system on each surface and the corresponding surface of the lens. In step S1, for example, the surface of the lens is cleaned by ultrasonic wave or hand rubbing. Specifically, in step S1, the surface of the lens is cleaned by ultrasonic wave by polishing with aluminum oxide polishing liquid and then ultrasonic pure water cleaning. For example, in step S1, the aluminum oxide polishing liquid uses 0.1μm polycrystalline diamond liquid of Nanjing Henry Precision Optics Co., Ltd. In step S1, for example, the product is a lens or a flat sheet. In step S1, for example, the thickness of the disc in the accompanying plating sheet is 2mm.

[0023] The temperature setting of the vacuum coating machine in step S2 heats the lens through the cavity of the coating machine, which helps the growth of the film layer from the lens and reduces the film layer growth stress.

[0024] Step S3 uses a Hall ion source for cleaning, which will separate the impurities and oil molecules adsorbed on the surface of each surface of the lens from the substrate surface, thereby greatly improving the interface state and helping to improve the bonding performance between the film layer and the corresponding surface of the lens. At the same time, cleaning through the Hall ion source can heat the corresponding surface of the lens, which helps the film layer grow from the lens and reduces the film layer growth stress.

[0025] In step S4, in one example, a Hall ion source is used as the ion source, and when the SiO film is deposited, the ion source parameters are: the neutralization current is 0.5A, the neutralization gas flow rate is 8sccm, the anode voltage is 120V, the anode current is 1.2A, the argon flow rate accounts for 30%, and the oxygen flow rate accounts for 70%; when the Ge film is deposited, the ion source parameters are: the neutralization current is 0.5A, the neutralization gas flow rate is 8sccm, the anode voltage is 120V, the anode current is 1.0A, and the argon flow rate accounts for 100%; when the ZnS film is deposited, the ion source parameters are: the neutralization current is 0.5A, the neutralization gas flow rate is 8sccm, the anode voltage is 120V, the anode current is 1.2A, and the argon flow rate accounts for 100%.

[0026] In step S4, in one example, argon gas is introduced and vacuum is drawn to maintain a constant flow vacuum when each film layer is deposited, and the constant flow vacuum is set to no less than 5.0×10 -3 Pa.

[0027] In step S4, for example, the crystal oscillator method is used to monitor the film thickness 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 new crystal oscillator of the multiple crystal oscillators to work accordingly, and the crystal oscillator frequency is not less than 5.99 MHz.

[0028] After step S6 is completed, in one example, the reflectivity of the wedge-shaped sheet in the accompanying coating sheet together with the film system corresponding to the first surface in the 2-2.3 μm band is less than 0.8% on average.

[0029] After step S6 is completed, in one example, the disc in the accompanying plating sheet together with the films on both sides pass the blister test, salt spray test, adhesion test, hot and cold shock test, constant temperature and humidity test, friction resistance test, low temperature test, and high temperature test.

[0030] [test]

[0031] Example 1

[0032] The method for preparing the 2-2.3 μm short-wave low-reflection film system on a germanium substrate of Example 1 adopts the following steps:

[0033] S1, cleaning the surfaces of the accompanying plating sheet and the product as the germanium substrate of the lens, wherein the accompanying plating sheet is a disc of equal thickness and a wedge-shaped sheet with a polished plane on the first side and a rough and rough surface on the second side, wherein the surface of the lens is cleaned by ultrasound, and the surface cleaning of the lens by ultrasound is polishing with aluminum oxide polishing liquid and then ultrasonic pure water cleaning, and the aluminum oxide polishing liquid is a 0.1μm polycrystalline diamond liquid of Nanjing Henry Precision Optics Co., Ltd., the thickness of the disc in the accompanying plating sheet is 2mm, and the product is a lens;

[0034] S2, loading the processed lens into a fixture, and hanging the fixture with the lens into the vacuum coating machine cavity, and setting the cavity temperature to 150°C;

[0035] S3, vacuum coating machine starts to evacuate, and the vacuum degree reaches 1.0×10 -3 Pa, turn on the Hall ion source of the vacuum coating machine for cleaning, the cleaning time is 6 minutes, the parameters of the Hall ion source are: anode voltage is 220V, anode current is 1.2A, neutralization current is 1.5A, neutralization gas flow rate is 10sccm, and argon gas flow rate is 100%;

[0036] S4, on the first side of the lens, a four-layer film system consisting of three film materials: SiO, Ge and ZnS

[0037] 34.8nmSiO / 64.3nmGe / 52.2nmZnS / 272.8nmSiO, sequentially deposit each film layer,

[0038] The numbers with nm before SiO, Ge and ZnS are the film thickness of the corresponding film layers. The SiO film layer and the Ge film layer are evaporated by electron beam heating, and the ZnS film layer is evaporated by resistance heating. The deposition rate of the SiO film layer is 0.6nm / s, the deposition rate of the Ge film layer is 0.3nm / s, and the deposition rate of the ZnS film layer is 0.8nm / s. Each film layer is deposited by ion source assisted deposition, and each film layer is deposited at a chamber temperature of 150°C.

[0039] In step S4,

[0040] The ion source adopts Hall ion source.

[0041] When depositing the SiO film layer, the ion source parameters are: neutralization current is 0.5A, neutralization gas flow rate is 8sccm, anode voltage is 120V, anode current is 1.2A, argon gas flow rate accounts for 30%, and oxygen flow rate accounts for 70%;

[0042] When depositing the Ge film layer, the ion source parameters are: neutralization current is 0.5A, neutralization gas flow rate is 8sccm, anode voltage is 120V, anode current is 1.0A, and argon gas flow rate is 100%;

[0043] When depositing the ZnS film, the ion source parameters are: neutralization current of 0.5 A, neutralization gas flow of 8 sccm, anode voltage of 120 V, anode current of 1.2 A, and argon gas flow ratio of 100%;

[0044] In step S4,

[0045] When depositing each film layer, argon gas was introduced and vacuum was drawn to maintain the flow constant vacuum. The flow constant vacuum was set to 5.0×10 -3 Pa;

[0046] 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 5.99MHz;

[0047] S5, after the coating system on the first side of the lens is completed, the chamber is naturally cooled to 60°C, and the fixture and the lens are taken out;

[0048] S6, repeating steps S1 to S5, coating the second surface of the lens with the same film system, wherein the wedge is not cleaned when step S1 is repeated and is not placed in a fixture when step S2 is repeated.

[0049] The wedge-shaped sheet in the accompanying plating sheet of Example 1 is used to test the reflectivity. Figure 3 Graph showing the reflectivity of the wedge-shaped sheet in the accompanying coating sheet of Example 1 together with the film system corresponding to the first surface. Figure 3 It can be seen that the reflectivity of the wedge-shaped sheet in the accompanying coating sheet together with the film system corresponding to the first surface in the 2-2.3 μm band is less than 0.8% on average.

[0050] After coating on both sides of the disc in the accompanying coating sheet of Example 1, the following test was performed.

[0051] Water bubble test: Take tap water to conduct a water bubble test for 2 hours to observe whether the film layers on each surface of the disc in the accompanying plating sheet fall off from the disc in the accompanying plating sheet, and observe whether the film layers on each surface of the disc in the accompanying plating sheet are cracked.

[0052] Salt spray test: neutral salt spray test for 48 hours, observe whether the film layer on each surface of the disc in the accompanying plating sheet falls off, and observe whether the film layer on each surface of the disc in the accompanying plating sheet cracks.

[0053] Adhesion test: Use hand to stick 3M tape on each side of the disc in the accompanying plating sheet and pull the tape in the direction opposite to the sticking end to observe whether the film layer is pulled up.

[0054] 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 surface of the disc in the accompanying plating sheet fall off or crack.

[0055] 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 surface of the discs in the accompanying plating sheet fall off, and observe whether the film layers on each surface of the discs in the accompanying plating sheet crack.

[0056] 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.

[0057] Low temperature test: In a low temperature box, at -40℃ for 48h, observe whether the film layers on each surface of the discs in the accompanying plating sheet fall off, and observe whether the film layers on each surface of the discs in the accompanying plating sheet crack.

[0058] High temperature test: In a high temperature box, at 85℃ for 48h, observe whether the film layers on each surface of the discs in the accompanying plating sheet fall off, and observe whether the film layers on each surface of the discs in the accompanying plating sheet crack.

[0059] In the blister test, salt spray test, hot and cold shock test, constant temperature and humidity test, low temperature test and high temperature test, the film layer did not fall off or crack; in the adhesion test, the film layer was not pulled up; in the friction test, there was no scratch damage on the surface of the film layer, that is, it was resistant to moderate friction. That is to say, the disc in the accompanying plating sheet of Example 1, together with the films on both sides, passed a total of eight tests, including the blister test, salt spray test, adhesion test, hot and cold shock test, constant temperature and humidity test, friction test, low temperature test and high temperature test.

[0060] 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. A method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate, characterized in that: Includes steps: S1, cleaning the surfaces of the accompanying plating sheet and the product as the germanium substrate of the lens, wherein the accompanying plating sheet is a round sheet of equal thickness and a wedge-shaped sheet with a polished flat surface on the first side and a rough rough surface on the second side; S2, loading the processed lens into the fixture, and hanging the fixture with the lens into the vacuum coating machine cavity, and setting the cavity temperature to 150°C; S3, vacuum coating machine starts to evacuate, and the vacuum degree reaches 1.0×10 -3 Pa, turn on the Hall ion source of the vacuum coating machine for cleaning, the cleaning time is 6 minutes, the parameters of the Hall ion source are: anode voltage is 220V, anode current is 1.2A, neutralization current is 1.5A, neutralization gas flow rate is 10sccm, and argon gas flow rate is 100%; S4, on the first side of the lens, a four-layer film system consisting of three film materials, SiO, Ge and ZnS, 34.8nmSiO / 64.3nmGe / 52.2nmZnS / 272.8nmSiO, is deposited in sequence. The numbers with nm before SiO, Ge and ZnS are the film thicknesses of the corresponding film layers. The SiO film layer and the Ge film layer are evaporated by electron beam heating, and the ZnS film layer is evaporated by resistance heating. The deposition rate of the SiO film layer is 0.6 nm / s, the deposition rate of the Ge film layer is 0.3 nm / s, and the deposition rate of the ZnS film layer is 0.8 nm / s. Each film layer is deposited by ion source assistance, and each film layer is deposited at a chamber temperature of 150°C. S5, after the coating system on the first side of the lens is completed, the cavity is naturally cooled to below 60°C, and the fixture and the lens are taken out; S6, repeating steps S1 to S5, coating the second surface of the lens with the same film system, wherein the wedge is not cleaned when step S1 is repeated and is not placed in a fixture when step S2 is repeated.

2. The method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to claim 1, characterized in that: In step S1, the surface of the lens is cleaned by ultrasonic wave or hand wiping.

3. The method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to claim 2, characterized in that: In step S1, the surface of the lens is cleaned by ultrasonic wave by polishing with aluminum oxide polishing liquid and then by ultrasonic pure water cleaning.

4. The method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to claim 3, characterized in that: In step S1, the aluminum oxide polishing liquid adopts the 0.1 μm polycrystalline diamond liquid produced by Nanjing Henry Precision Optics Co., Ltd.

5. The method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to claim 1, characterized in that: In step S1, the product is a lens or a flat sheet.

6. The method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to claim 1, characterized in that: In step S1, the thickness of the disc in the accompanying plating sheet is 2 mm.

7. The method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to claim 1, characterized in that: In step S4, The ion source adopts Hall ion source. When depositing the SiO film layer, the ion source parameters are: neutralization current is 0.5A, neutralization gas flow rate is 8sccm, anode voltage is 120V, anode current is 1.2A, argon gas flow rate accounts for 30%, and oxygen flow rate accounts for 70%; When depositing the Ge film layer, the ion source parameters are: neutralization current is 0.5A, neutralization gas flow rate is 8sccm, anode voltage is 120V, anode current is 1.0A, and argon gas flow rate is 100%; When depositing the ZnS film layer, the ion source parameters are: neutralization current is 0.5A, neutralization gas flow rate is 8sccm, anode voltage is 120V, anode current is 1.2A, and argon gas flow rate is 100%.

8. The method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to claim 1, characterized in that: In step S4, When coating each film layer, argon gas is introduced and vacuum is drawn to maintain the flow constant vacuum. The flow constant vacuum setting is not less than 5.0×10 -3 Pa; The crystal oscillator method is used to monitor the film thickness using the corresponding crystal oscillator pieces of the multiple crystal oscillator pieces of the crystal controller. After the ion source is cleaned, the crystal controller controls the corresponding operation of the new crystal oscillator pieces among the multiple crystal oscillator pieces, and the crystal oscillator frequency is not less than 5.99MHz.

9. The method for preparing a 2-2.3 μm short-wave low-reflection film system on a germanium substrate according to claim 1, characterized in that: After step S6 is completed, the reflectivity of the wedge-shaped sheet in the accompanying coating sheet together with the film system corresponding to the first surface in the 2-2.3 μm band is less than 0.8% on average; After step S6 is completed, the discs in the accompanying plating sheet together with the films on both sides pass the blister test, salt spray test, adhesion test, hot and cold shock test, constant temperature and humidity test, friction resistance test, low temperature test, and high temperature test.

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