Infrared optical material, preparation method and application thereof

Abstract

The application provides an infrared optical material and a preparation method and application thereof. The infrared optical material comprises a diamond substrate, a periodic micro-nano structure on one surface of the diamond substrate, a carbon nanotube film on the other surface of the diamond substrate, and an anti-reflection film on the carbon nanotube film. In one aspect, the micro-nano structure on one surface of the diamond substrate only changes the shape of the surface of the diamond substrate, does not change the performance of the material itself, avoids the problem of combination of the diamond substrate and the heterogeneous coating, reduces the infrared reflection of the surface, and improves the transmittance. In another aspect, the anti-reflection film can reduce infrared reflection, the carbon nanotube film between the surface of the diamond substrate and the anti-reflection film can improve the bonding force between the anti-reflection film and the diamond substrate, thereby improving the infrared transmittance of the diamond substrate, and meeting the application requirements of the infrared optical material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of infrared imaging technology, in particular to an infrared optical material and a preparation method and application thereof. BACKGROUND

[0002] The infrared optical window is an important component of structural and functional integration, which not only ensures the optical performance of the photoelectric system, but also protects the photoelectric system from being damaged by external factors. Therefore, the window material is required to have excellent optical performance and high mechanical performance to cope with complex application environments and meet the requirements of infrared detection work.

[0003] Commonly used infrared optical materials include germanium (Ge), zinc sulfide (ZnS), zinc selenide (ZnSe), gallium arsenide (GaAs), gallium phosphide (GaP), sapphire, magnesium fluoride, spinel, AlON and nano-composite ceramics, but they generally have low strength, and there is a trade-off between transmittance and mechanical strength, and they have poor reliability in complex environments. In contrast, diamond has good mechanical properties, chemical stability, and good optical transmittance in the infrared band, so diamond is an excellent infrared optical material.

[0004] The main problem of diamond as an infrared optical window material is that diamond has a high refractive index (n = 2.4). When infrared light with a wavelength of 8 μm to 12 μm passes through, the material has a reflection loss of up to 29%, resulting in a low theoretical transmittance limit of optical-grade diamond, only 71%, and different defects may occur during the growth and processing of the material itself, resulting in a lower actual transmittance, which cannot meet the requirements of infrared detection and other aspects. At the same time, due to the properties of the material itself, diamond has obvious absorption in the mid-wave infrared region. In practical applications, further antireflection is often needed to meet the application requirements of optical elements. SUMMARY

[0005] The purpose of the present application is to provide an infrared optical material to improve the optical performance of the material.

[0006] The first aspect of the present application provides an infrared optical material, which comprises a diamond substrate, a periodic micro-nano structure on one surface of the diamond substrate, a carbon nanotube film on the other surface of the diamond substrate, and an antireflection film on the carbon nanotube film.

[0007] In an embodiment of the present application, the thickness of the diamond substrate is 300 μm to 10 mm.

[0008] In an embodiment of the present application, the micro-nano structure is a three-dimensional structure selected from at least one of a conical structure, a sharp conical structure, a grating structure, a prismatic structure, a parabolic structure, a pyramid structure or a cylindrical structure.

[0009] In an embodiment of the present application, the micro-nano structure is an array structure with symmetry, the array structure is perpendicular to the surface of the diamond substrate, the period of the array structure is less than λ / n, wherein λ is the maximum wavelength of the incident infrared light waveband, and n is the refractive index of the diamond material; the height of the micro-nano structure is 100 nm to 3000 nm, the planar size of the array structure is ≤4 μm×4 μm, and the inclination angle is 0° to 30°.

[0010] In an embodiment of the present application, the carbon nanotube film is selected from at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes; and the thickness of the carbon nanotube film is 10 nm to 300 nm.

[0011] In an embodiment of the present application, the material of the antireflection film is selected from at least one of PbF2, YF3, BaF2, ZnS, ZnSe, TiO2, ZrO2, Y2O3, Yb2O3, HfO2, Al2O3, AlN, Si3N4, and a composite system thereof.

[0012] In an embodiment of the present application, the thickness of the antireflection film is 100 nm to 3000 nm.

[0013] In an embodiment of the present application, the infrared optical material has an infrared transmittance of ≥60% at a wavelength of 3 μm to 5 μm; and an infrared transmittance of ≥80% at a wavelength of 8 μm to 12 μm.

[0014] The second aspect of the present application provides a preparation method of the infrared optical material of the first aspect of the present application, which comprises: (1) polishing and cleaning the diamond substrate; (2) preparing a micro-nano structure on one surface of the diamond substrate; (3) preparing a carbon nanotube film on the other surface of the diamond substrate; and (4) preparing an antireflection film on the carbon nanotube film by using an evaporation method, a sputtering method or an ion plating method.

[0015] In an embodiment of the present application, the preparation of the micro-nano structure comprises: (1) evaporating a layer of titanium or aluminum on the surface of the diamond substrate, with a thickness of 100 nm to 130 nm; (2) spin-coating a layer of photoresist on the titanium or aluminum layer, with a thickness of 600 nm to 1 μm; (3) performing electron beam lithography on the surface of the photoresist, and then developing in a developing solution to obtain a mask pattern; and (4) performing etching by using an inductively coupled reactive ion etching method, using oxygen plasma etching, with a power of 100 W to 2000 W, an Ar gas flow rate of 10 sccm to 50 sccm, an oxygen flow rate of 10 sccm to 80 sccm, an SF6 gas flow rate of 0 sccm to 1 sccm, a gas pressure of 5 mTorr to 100 mTorr, a substrate power of 10 W to 200 W, and an etching time of 6 min to 20 min.

[0016] In one embodiment of the present application, the preparation of the carbon nanotube film includes: (1) forming a Ni catalyst film on a diamond substrate using a high-purity Ni target by magnetron sputtering, with an Ar gas flow rate of 10-100 sccm, a sputtering gas pressure of 1-50 Pa, a sputtering power of 10-500 W, and a pre-sputtering time of 1-10 min, followed by formal sputtering of the Ni film for 10-120 s; and (2) preparing the carbon nanotube film by chemical vapor deposition using CH4 as the carbon source, with a CH4 gas flow rate of 20-100 sccm, a H2 flow rate of 20-100 sccm, an Ar gas flow rate of 10-100 sccm, a temperature of 700-1000°C, and a time of 10-15 min.

[0017] The third aspect of the present application provides an infrared optical component comprising the infrared optical material of the first aspect of the present application or the infrared optical material prepared by the preparation method of the second aspect of the present application.

[0018] The present application has the following beneficial effects:

[0019] The present application provides an infrared optical material comprising a diamond substrate, a periodic micro-nano structure on one surface of the diamond substrate, a carbon nanotube film on the other surface of the diamond substrate, and an anti-reflection film on the carbon nanotube film. On the one hand, the micro-nano structure on one surface of the diamond substrate only changes the shape of the surface of the diamond substrate without changing the properties of the material itself, avoiding the problem of combining the diamond substrate with a heterogeneous coating, while reducing the infrared reflection of the surface and improving the transmittance. On the other hand, the anti-reflection film can reduce infrared reflection, and the carbon nanotube film between the surface of the diamond substrate and the anti-reflection film can improve the bonding force between the anti-reflection film and the diamond substrate, thereby improving the infrared transmittance of the diamond substrate and meeting the application requirements of the infrared optical material.

[0020] Of course, implementing any product or method of the present application does not necessarily require all the advantages described above to be achieved at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can also be obtained by those skilled in the art based on these drawings.

[0022] Figure 1 The micro-nano grating structure on one surface of the diamond substrate in Example 1-1;

[0023] Figure 2The micro-nano pyramid structure is a surface of a diamond substrate as described in Examples 1-7. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0025] To improve the transmittance of infrared optical materials, antireflective coatings are deposited on their surfaces. These coatings, also known as anti-reflection films, reduce reflection losses caused by surface reflection in optical elements, achieving an anti-reflection and anti-reflection effect. Commonly used antireflective coating materials include magnesium fluoride, silicon dioxide, and aluminum oxide. Alternatively, by fabricating microarray structures on the material surface and precisely controlling the parameters of the periodic structures, optical performance can be modulated, reducing or eliminating reflection at the material-air interface and achieving an anti-reflection and anti-reflection effect.

[0026] To meet the application requirements of diamond in the mid- and far-infrared regions, this application employs a method of preparing periodic micro- and nano-structures on one surface of a diamond substrate and preparing an antireflection film on the other surface to improve its infrared transmittance performance.

[0027] The first aspect of this application provides an infrared optical material comprising a diamond substrate, a periodic micro / nanostructure on one surface of the diamond substrate, a carbon nanotube film on another surface of the diamond substrate, and an antireflection coating on the carbon nanotube film. Diamond, being a carbon element, possesses a unique crystal structure that endows it with exceptionally superior mechanical, thermal, chemical, electrical, and optical properties that are difficult for many other materials to possess. Optical-grade diamond has an extremely wide spectral transmission range, exhibiting high transmittance in the infrared, visible, and ultraviolet (≥225 nm) regions, making it one of the most ideal materials for optical applications, especially under extreme conditions such as extremely high power densities and extremely harsh environments.

[0028] In one embodiment of this application, the thickness of the diamond substrate is from 300 μm to 10 mm. For example, the thickness of the diamond substrate can be 300 μm, 500 μm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, or a range of any two of these values. The diamond substrate possesses the above characteristics and exhibits good mechanical properties, chemical stability, and good optical transmittance in the infrared band.

[0029] In one embodiment of this application, the micro / nano structure is a three-dimensional structure, selected from at least one of a conical structure, a pointed cone structure, a grating structure, a frustum structure, a parabolic structure, a pyramid structure, or a cylindrical structure. For example... Figure 1 As shown in the diagram, the micro / nano grating structure is as follows. Figure 2 As shown in the diagram, the micro-nano pyramid structure is illustrated. By designing and fabricating the aforementioned micro-nano structures, and utilizing the interaction between the structure's scale and the wavelength of light, and by precisely controlling the shape, size, and periodicity of the micron or nano-scale structures, it is beneficial to alter the material's light propagation and reflection characteristics, reduce or eliminate reflection at the material-air interface, and achieve the effect of increasing light transmittance.

[0030] In one embodiment of this application, the micro / nanostructure is a symmetrical array structure perpendicular to the surface of the diamond substrate. The period of the array structure is less than λ / n, where λ is the maximum wavelength of the incident infrared light and n is the refractive index of the diamond material. The height of the micro / nanostructure is 100 nm to 3000 nm, the planar dimensions of the array structure are ≤4 μm × 4 μm, and the tilt angle is 0° to 30°. For example, the thickness of the micro / nanostructure can be 100 nm, 200 nm, 500 nm, 800 nm, 1200 nm, 1500 nm, 1800 nm, 2000 nm, 2200 nm, 2500 nm, 2800 nm, 3000 nm, or a range of any two of these values. The planar dimensions of the array structure are the side lengths of the three-dimensional micro / nanostructure on the diamond substrate surface, i.e., the length and width of the three-dimensional micro / nanostructure. For example, the planar dimensions of the array structure can be 0.1μm×0.1μm, 0.5μm×0.5μm, 1μm×1μm, 1.5μm×1.5μm, 2μm×2μm, 2.5μm×2.5μm, 3μm×3μm, 3.5μm×3.5μm, 4μm×4μm, or any combination of two of these values; the tilt angle is the angle between the side of the three-dimensional micro / nano structure and the vertical line of the diamond substrate surface, which can be 0°, 5°, 10°, 15°, 20°, 25°, 30°, or any combination of two of these values. For the applied infrared band, by adjusting the side length and tilt angle of the micro / nano structure within the above ranges, and ensuring the period of the array structure is less than λ / n, the anti-reflection effect is improved.

[0031] In one embodiment of this application, the carbon nanotube film includes at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes; the thickness of the carbon nanotube film is from 10 nm to 300 nm. For example, the thickness of the carbon nanotube film can be 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, or a range of any two of these values. Carbon nanotubes have good optical properties and high infrared transmittance, making them suitable for infrared optical windows. By selecting the above-mentioned type of carbon nanotube film and controlling the thickness within the above range, a carbon nanotube film is prepared on one surface of a diamond substrate, improving the adhesion between the diamond substrate surface and the antireflective coating, reducing the risk of antireflective coating peeling or detachment during use, thereby improving the infrared transmittance of the diamond substrate and meeting application requirements.

[0032] In one embodiment of this application, the antireflective coating material is selected from at least one of PbF2, YF3, BaF2, ZnS, ZnSe, TiO2, ZrO2, Y2O3, Yb2O3, HfO2, Al2O3, AlN, Si3N4, and their composite systems. The antireflective coating is typically composed of a single layer or multiple layers of materials with different refractive indices. By adjusting the thickness and refractive index of the coating layers, antireflection of specific wavelengths is achieved. When light passes through the multilayer coating material, partial reflection and transmission occur at the interface due to the difference in refractive index. Based on the coherence of light, the reflected and transmitted waves interfere with each other, resulting in the enhancement of light at a specific wavelength. Depending on the application requirements, at least one of the above materials is selected based on their different refractive indices. By adjusting the combination and thickness of the materials, an antireflective coating is prepared, resulting in infrared optical materials with excellent antireflective performance.

[0033] In one embodiment of this application, the thickness of the antireflection film is from 100 nm to 3000 nm. For example, the thickness of the antireflection film can be 100 nm, 500 nm, 800 nm, 1000 nm, 1200 nm, 1500 nm, 1800 nm, 2000 nm, 2200 nm, 2500 nm, 2800 nm, 3000 nm, or a range of any two values ​​therein. The antireflection film can reduce the reflection loss of light on the surface of the component. When light is reflected from the two surfaces of the antireflection film, if the optical path difference between the two reflected beams is an odd multiple of half the wavelength, the reflected light will coherently cancel each other out, thereby enhancing the refracted light and reducing the reflection loss. Therefore, the thickness of the antireflection film is precisely controlled for a specific wavelength and material. When the thickness of the antireflection film is controlled within the above range, the micro-nano structures on one surface of the diamond substrate and the antireflection film on the other surface combine to help the reflected light coherently cancel each other out, reduce the reflection loss, and improve the infrared transmittance of the diamond substrate.

[0034] In one embodiment of this application, the infrared optical material has an infrared transmittance of ≥60% in the wavelength range of 3μm to 5μm; and an infrared optical material has an infrared transmittance of ≥80% in the wavelength range of 8μm to 12μm. For example, the infrared transmittance of the infrared optical material in the wavelength range of 3μm to 5μm can be 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99.9%, or any two of these values; the infrared transmittance of the infrared optical material in the wavelength range of 8μm to 12μm can be 80%, 82%, 84%, 88%, 90%, 92%, 94%, 96%, 98%, 99.9%, or any two of these values. When the infrared optical material has an infrared transmittance of ≥60% in the wavelength range of 3μm to 5μm and an infrared transmittance of ≥80% in the wavelength range of 8μm to 12μm, the infrared optical material has good optical transmittance in the working infrared band and can meet the application requirements of optical components.

[0035] In this application, the materials used in the infrared optical materials, such as the diamond substrate, carbon nanotubes, and antireflective coating, are all commercially available conventional substances. This application does not impose any special restrictions on their sources, as long as they can achieve the purpose of this application.

[0036] The second aspect of this application provides a method for preparing the infrared optical material described in the first aspect of this application, comprising: (1) polishing and cleaning a diamond substrate; (2) preparing a micro-nano structure on one surface of the diamond substrate; (3) preparing a carbon nanotube film on another surface of the diamond substrate; and (4) preparing an antireflection film on the carbon nanotube film by vapor deposition, sputtering or ion plating.

[0037] In some implementations, there are no particular restrictions on the polishing of the diamond substrate, as long as the purpose of this application can be achieved.

[0038] In some embodiments, there are no particular limitations on the cleaning of the diamond substrate, as long as the purpose of this application can be achieved. For example, surface impurities can be removed by heating and soaking in at least one solution selected from perchloric acid, nitric acid, sulfuric acid, permanganic acid, and hydrogen peroxide for 10 to 180 minutes, with the concentration of the soaking solution being 10% to 80%. Then, ultrasonic cleaning is performed in acetone solution or alcohol for 5 to 60 minutes, with the acetone solution concentration being 50% to 90%. Finally, ultrasonic cleaning is performed repeatedly with deionized water for 1 to 60 minutes. Drying is then performed using a blower or drying oven at a temperature of 50°C to 100°C for 1 to 10 minutes. For example, the concentration of the soaking solution can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or any combination of two of these values; the concentration of the acetone solution can be 50%, 60%, 70%, 80%, 90%, or any combination of two of these values.

[0039] In some implementations, the alcohol used in this application is a commercially available conventional substance, as long as it achieves the purpose of this application. For example, the concentration can be 98% alcohol.

[0040] In one embodiment of this application, the fabrication of the micro / nano structure includes: (1) depositing a layer of titanium or aluminum on the surface of a diamond substrate with a thickness of 100 nm to 130 nm; (2) spin-coating a layer of photoresist on the titanium or aluminum layer with a thickness of 600 nm to 1 μm; (3) performing electron beam lithography on the photoresist surface, followed by development in a developing solution to obtain a mask pattern; (4) performing etching using an inductively coupled reactive ion etching method, utilizing oxygen plasma etching with a power of 100 W to 2000 W, an Ar gas flow rate of 10 sccm to 50 sccm, an oxygen flow rate of 10 sccm to 80 sccm, an SF6 gas flow rate of 0 sccm to 1 sccm, a gas pressure of 5 sccm to 100 mTorr, a substrate power of 10 W to 200 W, and an etching time of 6 min to 20 min.

[0041] In some implementations, there are no particular limitations on the step of vapor-depositing a layer of titanium or aluminum onto the diamond substrate surface, as long as the purpose of this application can be achieved. For example, the vapor deposition process can be vacuum vapor deposition, in which titanium material is placed in a heating system under vacuum conditions and heated to evaporate, and the metal vapor condenses on the diamond surface, at a vacuum level of 0.1 Pa to 10 Pa, a temperature of 600°C to 750°C, and a time of 1 min to 30 min.

[0042] In some implementations, there are no particular restrictions on the spin coating method of photoresist on the titanium or aluminum layer, as long as the purpose of this application can be achieved. For example, the spin coating method can be to fill the surface of the titanium or aluminum layer with photoresist, and then coat the surface with photoresist by means of self-rotation, centrifugal force and interfacial tension.

[0043] In one embodiment of this application, a layer of titanium or aluminum is deposited on the surface of a diamond substrate, with a thickness of 100 nm to 130 nm. For example, the thickness of the titanium or aluminum layer can be 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, or any combination of two of these values. The thickness of the surface titanium or aluminum layer and the photoresist affects the accuracy and resolution of the final micro / nano structure pattern. Therefore, controlling the thickness of the titanium or aluminum layer within the above-mentioned range helps to reduce the risk of pattern distortion in the micro / nano structure and improve the clarity and dimensional accuracy of the pattern.

[0044] In one embodiment of this application, the thickness of the photoresist is from 600 nm to 1 μm. For example, it can be 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1 μm, or a range of any two of these values. The thickness of the surface titanium or aluminum layer and the photoresist affects the accuracy and resolution of the final micro / nano structure pattern. By controlling the thickness of the photoresist within the above-mentioned range, it is beneficial to improve the clarity of the micro / nano structure pattern.

[0045] In some implementations, the photoresist is a flowable inorganic polymer, a commercially available conventional material. This application does not have any particular restrictions on its source, as long as it can achieve the purpose of this application.

[0046] In some implementations, there are no particular limitations on the method of electron beam lithography on the photoresist surface, as long as the purpose of this application can be achieved. For example, the electron beam lithography method can be an electron beam with an energy of 50 keV to 500 keV and a current of 10 μC / cm. 2 Up to 100 μC / cm 2 The dose directly irradiates the photoresist layer.

[0047] In one embodiment of this application, etching is performed using inductively coupled reactive ion etching (ICD), utilizing oxygen plasma etching with a power of 100W to 2000W, an Ar gas flow rate of 10sccm to 50sccm, an oxygen flow rate of 10sccm to 80sccm, an SF6 gas flow rate of 0sccm to 1sccm, a gas pressure of 5mTorr to 100mTorr, a substrate power of 10W to 200W, and an etching time of 6min to 20min. For example, the power rating can be 100W, 200W, 300W, 400W, 500W, 600W, 700W, 800W, 900W, 1000W, 1100W, 1200W, 1300W, 1400W, 1500W, 1600W, 1700W, 1800W, 1900W, 2000W, or a range of any two of these values; the Ar gas flow rate can be 10 sccm, 15 sccm, 20 sccm, 25 sccm, 30 sccm, 35 sccm. 40 sccm, 45 sccm, 50 sccm, or any two of these values; oxygen flow rate can be 10 sccm, 15 sccm, 20 sccm, 25 sccm, 30 sccm, 35 sccm, 40 sccm, 45 sccm, 50 sccm, 55 sccm, 60 sccm, 65 sccm, 70 sccm, 75 sccm, 80 sccm, or any two of these values; SF6 gas flow rate can be 0 sccm, 0.2 sccm, 0.4 sccm, 0.6 sccm, 0.8 sccm, 1 sccm, or any two of these values; gas pressure can be 5 mTorr, 10 mTorr, 20 mTorr, 30 mTorr, 40 mTorr, 50 mTorr, 60 mTorr, 70 mTorr, 80 mTorr, 90 mTorr, 100 mTorr, or any two of these values; substrate power can be 10 W, 20 W, 30 W, 40 W, 50 W, 60 W, 70 W. The values ​​can be 80W, 90W, 100W, 110W, 120W, 130W, 140W, 150W, 160W, 170W, 180W, 190W, 200W, or any two of these values; the etching time can be 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min, 20min, or any two of these values.The etching power and working gas pressure, among other parameters, have a significant impact on the etching effect. By adjusting these parameters within the range of the inductively coupled reactive ion etching method, it is beneficial to accurately control the parameters of the periodic structure, increase plasma density and ion flux, increase the etching rate, reduce mask consumption, reduce the risk of substrate damage, improve the patterning accuracy of micro-nano structures, and improve the transmittance of infrared optical materials.

[0048] In some solutions, there are no particular restrictions on the cleaning and removal methods for the titanium or aluminum layers and photoresist on the diamond substrate surface.

[0049] For example, it can be removed by soaking in an HF solution.

[0050] In one embodiment of this application, the preparation of carbon nanotube thin films includes: (1) forming a Ni catalyst thin film on a diamond substrate using a high-purity Ni target for magnetron sputtering, with an Ar gas flow rate of 10 sccm to 100 sccm, a sputtering pressure of 1 Pa to 50 Pa, a sputtering power of 10 W to 500 W, and after pre-sputtering for 1 min to 10 min, formally sputtering the Ni thin film for a sputtering time of 10 s to 120 s; (2) preparing carbon nanotube thin films using chemical vapor deposition, with CH4 as the carbon source, a CH4 gas flow rate of 20 sccm to 100 sccm, an H2 flow rate of 20 sccm to 100 sccm, an Ar gas flow rate of 10 sccm to 100 sccm, a temperature of 700 °C to 1000 °C, and a time of 10 min to 15 min.

[0051] A Ni catalyst film is formed on a diamond substrate using a high-purity Ni target for magnetron sputtering. The Ar gas flow rate is 10 sccm to 100 sccm, the sputtering pressure is 1 Pa to 50 Pa, and the sputtering power is 10 W to 500 W. After pre-sputtering for 1 to 10 minutes, the Ni film is then sputtered for 10 to 120 seconds. For example, the Ar gas flow rate can be 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 90 sccm, 100 sccm, or any two of these values; the sputtering pressure can be 1 Pa, 5 Pa, 10 Pa, 15 Pa, 20 Pa, 25 Pa, 30 Pa, 35 Pa, 40 Pa, 45 Pa, 50 Pa, or any two of these values; and the sputtering power can be 10 W, 50 W, 100 W, 150 W, 200 W, 50 W, 100 W, 150 W, 200 W, 1 ... The pre-sputtering time can be 1 min, 2 min, 300 W, 350 W, 400 W, 450 W, 500 W, or any two of these values; the pre-sputtering time can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, or any two of these values; the final sputtering time can be 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 120 s, or any two of these values.

[0052] Carbon nanotube films were prepared by chemical vapor deposition (CVD) using CH4 as the carbon source. The CH4 gas flow rate was 20 sccm to 100 sccm, the H2 flow rate was 20 sccm to 100 sccm, the Ar gas flow rate was 10 sccm to 100 sccm, the temperature was 700℃ to 1000℃, and the time was 10 min to 15 min. For example, the CH4 gas flow rate could be 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, or any combination of two of these values; the H2 flow rate could be 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, or any combination of two of these values; and the Ar gas flow rate could be 10 sccc. The parameters for preparing carbon nanotube films are: m, 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, or any combination of two of these values; the temperature is: 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, or any combination of two of these values; the time is: 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, or any combination of two of these values. By controlling the above parameters within the scope of this application, it is beneficial to control the growth process of carbon nanotube films, increasing the density and reducing the diameter of carbon nanotubes while improving their dispersion. It also helps to improve the bonding force between the diamond substrate and the antireflective coating, producing uniform and high-quality carbon nanotube films, reducing the risk of antireflective coating peeling and detachment during use, thereby improving the infrared transmittance of the diamond substrate and meeting application requirements.

[0053] In one embodiment of this application, there are no particular restrictions on the preparation of antireflection films on carbon nanotube films by vapor deposition, sputtering or ion plating, as long as the purpose of this application can be achieved.

[0054] In some implementations, the antireflection film is prepared on a carbon nanotube film using a vapor deposition method, including but not limited to the following steps:

[0055] (1) Place a diamond substrate with micro-nano structure and carbon nanotube film into an evaporation coating device; (2) Use resistance heating evaporation or electron beam heating evaporation to form an antireflection film on the surface of the carbon nanotube film.

[0056] In some implementations, the antireflection film is prepared on a carbon nanotube film using a sputtering method, including but not limited to the following steps:

[0057] (1) Place a diamond substrate with micro-nano structure and carbon nanotube film into a magnetron sputtering device; (2) Deposit an antireflection film on the surface of the carbon nanotube film.

[0058] In some implementations, the preparation of an antireflective film on a carbon nanotube film by ion plating includes, but is not limited to, the following steps: (1) placing a diamond substrate in an ion plating machine and heating the diamond substrate under vacuum; (2) preparing the material for the antireflective film into powder or block form and placing it in a beam source, which generates a high-temperature ion beam after heating; (3) placing the diamond substrate in front of the ion beam, which bombards the surface of the diamond substrate on which the carbon nanotube film is prepared, generating a chemical reaction and causing the antireflective film to be deposited on the surface of the carbon nanotube film.

[0059] In this application, the materials used in the preparation method of infrared optical materials are all commercially available conventional substances. This application does not have any special restrictions on their source, as long as they can achieve the purpose of this application.

[0060] In this application, there are no particular limitations on the chemical vapor deposition equipment, vacuum evaporation coating equipment, sputtering coating equipment, ion plating equipment, and ion etching equipment used in the preparation method of infrared optical materials, as long as they can achieve the purpose of this application.

[0061] A third aspect of this application provides an infrared optical component, which includes the infrared optical material described in the first aspect of this application or the infrared optical material prepared by the preparation method described in the second aspect of this application.

[0062] Example

[0063] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0064] Test methods and equipment:

[0065] Infrared transmittance test:

[0066] The equipment used is a Fourier transform infrared spectrometer. (1) Fix the infrared optical material sample of the example or comparative example in the sample holder and place it in the center of the equipment cavity; (2) Test the infrared light transmittance according to the required infrared band, and obtain the transmittance spectrum after software calculation to obtain transmittance data.

[0067] Example 1-1

[0068] <Cleaning the diamond substrate>

[0069] The diamond substrate, after double-sided polishing, was immersed in a 20% sulfuric acid aqueous solution heated to 60°C for 60 minutes to remove surface impurities. It was then ultrasonically cleaned in an 80% acetone aqueous solution for 20 minutes, followed by ultrasonic cleaning with deionized water for 10 minutes. After multiple deionized water cleanings, it was dried in a drying oven at 60°C for 5 minutes. The thickness of the diamond substrate was 1 mm.

[0070] <Preparation of Micro / Nano Structures>

[0071] Micro-nano grating structures were fabricated on one surface of a diamond substrate. First, a 100 nm thick layer of titanium was deposited on one surface of the diamond substrate. Then, a 1 μm thick layer of photoresist (HSQ) was spin-coated onto the titanium-deposited diamond substrate. Electron beam lithography was performed on the photoresist surface, and the lithographic sample was immersed in a developing solution to obtain a periodically arranged mask pattern.

[0072] In the cavity of the inductively coupled plasma device, oxygen plasma etching was performed using a power of 600W, an Ar gas flow rate of 10 sccm, an O2 gas flow rate of 20 sccm, an SF6 gas flow rate of 0 sccm, a gas pressure of 5 mTorr, a substrate power of 80W, and an etching time of 20 min. Finally, the sample was immersed in a 30% HF aqueous solution for 30 min to remove residual titanium and photoresist on the surface.

[0073] In Example 1-1, a micro / nano grating structure on one surface of a diamond substrate has a planar dimension of 0.85 μm × 0.85 μm, a thickness of 1700 nm, a period of 1.4 μm, and a tilt angle of 0°. Figure 1 As shown.

[0074] <Preparation of carbon nanotube thin films>

[0075] Carbon nanotube films were prepared on another surface of a diamond substrate. The diamond substrate was placed in a magnetron sputtering apparatus, using a high-purity Ni target, an Ar gas flow rate of 20 sccm, a sputtering pressure of 2 Pa, a sputtering power of 70 W, and a pre-sputtering time of 5 min before the Ni film was sputtered for 50 s.

[0076] The diamond substrate was then placed in a tube furnace chemical vapor deposition system to deposit a carbon nanotube film. The growth conditions were: CH4 gas flow rate of 60 sccm, H2 gas flow rate of 40 sccm, Ar gas flow rate of 100 sccm, temperature of 850℃, and growth time of 10 min, resulting in a 130 nm carbon nanotube film.

[0077] <Preparation of Antireflective Membranes>

[0078] Antireflection layers were prepared on carbon nanotube films using an evaporation deposition method. Based on the antireflection requirements in the infrared wavelength range of 3 μm to 5 μm, ZnS, YF3, and Y2O3 were selected as the antireflection films, with a total film thickness of 1000 nm. A diamond substrate with micro / nano structures and carbon nanotube films was placed in an evaporation deposition apparatus, and a vacuum of 1000 nm was applied. -3 Below Pa, the bias voltage is 120V, the discharge current is 50A, the Ar flow rate is 4sccm, and the working temperature is 150℃. Using the resistance heating evaporation method, a ZnS film is first deposited on the surface of a nanotube film prepared on a diamond substrate. The current is 200A, the evaporation rate is 1.1nm / s, and the ZnS film thickness is 400nm.

[0079] YF3 thin films were further deposited by electron beam heating and evaporation. The evaporation electron beam current was 60 mA, the evaporation rate was 1.2 nm / s, and the YF3 film thickness was 120 nm.

[0080] Y2O3 was deposited by electron beam heating and evaporation. The electron beam current was 480 mA, the evaporation rate was 0.5 nm / s, the Y2O3 film was 480 nm thick, and the film was cooled to room temperature to obtain the infrared optical material in Example 1-1.

[0081] Examples 1-2 to 1-21

[0082] Except for adjusting the relevant parameters according to Table 1, everything else is the same as in Example 1-1.

[0083] Comparative Example 1

[0084] Except that after polishing and cleaning the diamond substrate, one surface of the diamond substrate is not prepared with micro / nano structures, and the other surface is not prepared with carbon nanotube films and antireflective films, the rest is the same as in Example 1-1.

[0085] Comparative Examples 2 to 3

[0086] Except for adjusting the relevant parameters according to Table 1, everything else is the same as in Example 1-1.

[0087] Comparative Example 4

[0088] Except for polishing and cleaning the diamond substrate according to Table 1, not preparing micro / nano structures on one surface of the diamond substrate, not preparing carbon nanotube films and antireflective films on the other surface, and changing the maximum wavelength of the incident infrared band, the rest is the same as in Example 1.

[0089] Comparative Examples 5 to 6

[0090] Except for adjusting the relevant parameters according to Table 1, everything else is the same as in Example 1-1.

[0091] The preparation parameters and performance parameters of each embodiment and comparative example are shown in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] Note: In Table 1, “\” indicates that there is no corresponding preparation parameter, substance or performance parameter.

[0096] In infrared optical materials, the fabrication parameters of the periodic micro / nanostructures on one surface of a diamond substrate, the carbon nanotube film on another surface of the diamond substrate, and the antireflection coating on the carbon nanotube film affect the optical performance of the infrared optical materials. As can be seen from Examples 1-1 to 1-21 and Comparative Examples 1 to 6, when the fabrication parameters of the micro / nanostructures on one surface of the diamond substrate and the antireflection coating on the other surface are within the scope of this application, the infrared light bands of 3μm to 5μm and 8μm to 12μm exhibit high transmittance when passing through the infrared optical materials prepared in the examples, demonstrating that the infrared optical materials prepared in the examples possess good optical performance.

[0097] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0098] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0099] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An infrared optical material comprising a diamond substrate, a periodic micro / nanostructure on one surface of the diamond substrate, a carbon nanotube film on another surface of the diamond substrate, and an antireflective coating on the carbon nanotube film; wherein, The micro / nano structure is a symmetrical array structure, which is perpendicular to the surface of the diamond substrate. The period of the array structure is less than λ / n, where λ is the maximum wavelength of the incident infrared light and n is the refractive index of the diamond material. The height of the micro / nano structure is 100nm to 3000nm, the planar size of the array structure is ≤4μm×4μm, and the tilt angle is 0° to 30°. The carbon nanotube film is selected from at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes; the thickness of the carbon nanotube film is from 10 nm to 300 nm. The infrared optical material has an infrared transmittance of ≥60% in the wavelength range of 3μm to 5μm; the infrared optical material has an infrared transmittance of ≥80% in the wavelength range of 8μm to 12μm.

2. The infrared optical material according to claim 1, wherein, The thickness of the diamond substrate is from 300 μm to 10 mm.

3. The infrared optical material according to claim 1, wherein, The micro / nano structure is a three-dimensional structure, selected from at least one of the following: conical structure, pointed cone structure, grating structure, truncated pyramid structure, parabolic structure, pyramid structure, or cylindrical structure.

4. The infrared optical material according to claim 1, wherein, The antireflective membrane is made of at least one of PbF2, YF3, BaF2, ZnS, ZnSe, TiO2, ZrO2, Y2O3, Yb2O3, HfO2, Al2O3, AlN, Si3N4 and their composite systems.

5. The infrared optical material according to claim 1, wherein, The thickness of the antireflective coating is from 100 nm to 3000 nm.

6. A method for preparing an infrared optical material according to any one of claims 1 to 5, comprising: (1) Polish and clean the diamond substrate; (2) A micro / nano structure is fabricated on one surface of the diamond substrate; (3) Prepare a carbon nanotube film on another surface of the diamond substrate; (4) An antireflective film is prepared on the carbon nanotube film by vapor deposition, sputtering or ion plating.

7. The method for preparing infrared optical materials according to claim 6, wherein, The fabrication of the micro / nano structures includes: (1) A layer of titanium or aluminum is vapor-deposited on the surface of a diamond substrate, with a thickness of 100 nm to 130 nm; (2) A layer of photoresist with a thickness of 600 nm to 1 μm is spin-coated onto the titanium or aluminum layer; (3) Electron beam lithography is performed on the photoresist surface, and then the surface is placed in a developing solution to obtain a mask pattern; (4) Etching is performed using inductively coupled reactive ion etching (ICD), with oxygen plasma etching. The power is 100W to 2000W, the Ar gas flow rate is 10sccm to 50sccm, the oxygen flow rate is 10sccm to 80sccm, the SF6 gas flow rate is 0sccm to 1sccm, the gas pressure is 5mTorr to 100mTorr, the substrate power is 10W to 200W, and the etching time is 6min to 20min.

8. The method for preparing infrared optical materials according to claim 6, wherein, The preparation of the carbon nanotube thin film includes: (1) A Ni catalyst film is formed on a diamond substrate using a high-purity Ni target for magnetron sputtering. The Ar gas flow rate is 10 sccm to 100 sccm, the sputtering pressure is 1 Pa to 50 Pa, the sputtering power is 10 W to 500 W, and after pre-sputtering for 1 min to 10 min, the Ni film is sputtered for 10 s to 120 s. (2) Carbon nanotube films were prepared by chemical vapor deposition, with CH4 as the carbon source, CH4 gas flow rate of 20 sccm to 100 sccm, H2 flow rate of 20 sccm to 100 sccm, Ar gas flow rate of 10 sccm to 100 sccm, temperature of 700℃ to 1000℃, and time of 10 min to 15 min.

9. An infrared optical component comprising an infrared optical material according to any one of claims 1 to 5 or an infrared optical material prepared by any one of claims 6 to 8.

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