High-reflectivity optical element based on magnesium-based reflecting layer and preparation method of high-reflectivity optical element

Abstract

The invention relates to the field of optical elements, and discloses a high-reflectivity optical element based on a magnesium-based reflecting layer, which comprises a substrate layer serving as a support body, a magnesium reflecting layer and a protective layer are sequentially attached to the surface of the substrate layer, and the magnesium reflecting layer is formed by depositing metal magnesium under a vacuum plating process. And the protective layer is deposited on the surface of the magnesium reflecting layer and protects the magnesium reflecting layer. According to the scheme, the ultrahigh reflecting mirror with high reflectivity on the ultraviolet light band and the near ultraviolet light band is obtained by utilizing the high reflectivity of the magnesium metal on the ultraviolet light band and the near ultraviolet light band, meanwhile, oxygen and water vapor are effectively blocked through the protective layer, so that the durability of the reflecting mirror is greatly improved, the durability is verified through a salt spray test and a damp heat test, and the service life of the reflecting mirror is prolonged. After 500 hours, the reflectivity is attenuated by lt; 5%.

Description

Technical Field

[0001] This solution relates to the field of optical components, specifically to high-reflectivity optical components based on magnesium-based reflective layers and their fabrication methods. Background Technology

[0002] Metal thin-film mirrors are key components in optical systems. Currently, the most commonly used high-reflectivity mirrors typically employ vacuum-deposited aluminum (Al) as the reflective layer due to its excellent reflectivity in the visible light region, good chemical stability, and low cost. However, aluminum films exhibit low reflectivity in the ultraviolet (UV) band, and their reflectivity has already approached its theoretical limit in some high-end applications, making further improvement difficult. Research indicates that magnesium (Mg) has a higher theoretical reflectivity than aluminum in both the UV and near-UV bands, making it an ideal material for fabricating ultra-high-reflectivity mirrors. However, magnesium is chemically extremely reactive and oxidizes rapidly in air, leading to a significant decrease in reflectivity. Furthermore, the porous oxide layer cannot prevent further oxidation of the magnesium, causing the magnesium film to pulverize and detach, rendering it unusable in practical applications.

[0003] In existing technologies, most reports on attempts to vapor-deposit magnesium films are concentrated in the laboratory, but due to their poor durability, a reliable industrialization solution has yet to be developed. Therefore, how to prepare magnesium-based reflective films that can retain the high reflectivity of magnesium and be used stably for a long time has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The present invention aims to provide a high-reflectivity optical element based on a magnesium-based reflective layer and a method for fabricating the same, so as to obtain an optical element with high reflectivity in the ultraviolet range by using metallic magnesium to fabricate the reflective layer.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a high reflectivity optical element based on a magnesium-based reflective layer, comprising a substrate layer as a support, wherein the substrate layer is made of a material with a transmittance of more than 80% for light with wavelengths less than 400nm, and a magnesium reflective layer and a protective layer are sequentially attached to the surface of the substrate layer, wherein the magnesium reflective layer is formed by depositing metallic magnesium under a vacuum plating process, and the protective layer is deposited on the surface of the magnesium reflective layer and protects the magnesium reflective layer.

[0006] The beneficial effects of this solution are as follows: This solution effectively blocks oxygen and water vapor through a protective layer, and utilizes the high reflectivity of magnesium in the ultraviolet band to obtain an optical element with high reflectivity in the ultraviolet band. At the same time, the reflective layer formed by the deposition of magnesium in the vacuum plating process is wrapped on both sides by a base layer and a protective layer, respectively. During use, oxygen, carbon dioxide and water vapor in the air need to pass through the base layer or the protective layer to react with the magnesium, which greatly improves the durability of the reflector. The durability is verified by salt spray test and damp heat test. After 500 hours, the reflectivity decay is <5%.

[0007] Furthermore, the thickness of the magnesium reflective layer is between 80 and 10,000 nm.

[0008] Beneficial effects: Setting the thickness of the magnesium reflective layer to 80-10000nm can avoid the formation of island-like growth of metallic magnesium during deposition, which would result in very low reflectivity and fail to meet the requirements for high reflectivity. It can also avoid the waste of metallic magnesium.

[0009] Furthermore, the protective layer is made of at least one of magnesium fluoride, aluminum oxide, or silicon dioxide, and its total thickness ranges from 30 to 150 nm. Setting the thickness of the protective layer between 30 and 150 nm ensures that the protective layer completely covers the metallic magnesium forming the magnesium reflective layer, thereby preventing the metallic magnesium from contacting the air and affecting the durability of the magnesium reflective layer.

[0010] Furthermore, the protective layer has a double-layer structure, which includes a dense layer and a wear-resistant layer. One side of the dense layer is attached to the surface of the magnesium reflective layer and serves as a support for the wear-resistant layer, while the wear-resistant layer is attached to the surface of the dense layer.

[0011] Furthermore, the dense layer is made of alumina with a thickness of not less than 20 nm, and the wear-resistant layer is made of silicon dioxide with a thickness of not less than 80 nm.

[0012] Furthermore, the substrate layer is selected from one of calcium fluoride glass, quartz glass, borosilicate glass, or optical glass.

[0013] Furthermore, the substrate layer can be made of one of the following materials: nano-metal film, glass, acrylic, polycarbonate, quartz, or ceramic.

[0014] Furthermore, the fabrication method includes the following steps: S1 Substrate preparation: The substrate surface is cleaned and dried to obtain a clean substrate layer; S2 Vacuum environment: The substrate obtained in S1 and the coating material are placed in a high vacuum coating machine, and the vacuum chamber is evacuated to a depth of 9*10. -6 -5*10 -2 Pa;S3 coating, using a high vacuum coating machine, sequentially deposits a magnesium reflective layer and a protective layer on the substrate surface.

[0015] Furthermore, the S3 coating includes S31 heating, S32 magnesium reflective layer deposition, and S33 protective layer deposition. Specifically, S31 heating involves heating the evaporation boat to room temperature -1500℃, while controlling the substrate temperature to room temperature -300℃; S32 magnesium reflective layer deposition involves controlling the distance between the evaporation boat and the substrate to 100-700mm, controlling the substrate stage rotation to ≤25r / min, controlling the deposition rate to 0.01nm / s-999nm / s, placing a magnesium ingot into the evaporation boat to obtain magnesium vapor, and depositing the magnesium vapor on the substrate surface to obtain a magnesium reflective layer with a thickness between 80-10000nm; and S33 protective layer deposition involves depositing at least one of magnesium fluoride, alumina, or silicon dioxide onto the magnesium reflective layer surface using PECVD in-situ deposition without disrupting the vacuum, to obtain a protective layer with a thickness between 30-150nm. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a flowchart of an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of Embodiment 2 of the present invention.

[0017] The reference numerals in the accompanying drawings include: base layer 1, magnesium reflective layer 2, protective layer 3, dense layer 31, and wear-resistant layer 32. Detailed Implementation

[0018] Example 1 Example 1 is basically as shown in the appendix. Figure 1-2 As shown, Figure 1-2 The high-reflectivity optical element based on a magnesium-based reflective layer shown is, for example... Figure 1 As shown, the structure includes a base layer 1, a magnesium reflective layer 2, and a protective layer 3. The base layer 1 serves as a support and can be selected from soda-lime glass, quartz glass, borosilicate glass, or optical glass with a light transmittance greater than 80%. In this embodiment, the base layer 1 is selected from BF33 quartz glass produced by Schott Glass Works in Germany or SK-1300 quartz glass produced by Ohara Glass Works in Japan. The magnesium reflective layer 2 is a metal film with a thickness ranging from 80 to 10,000 nm, formed by depositing 99.99% pure magnesium ingots on the surface of the base layer 1. The protective layer 3 is formed by depositing at least one of magnesium fluoride, alumina, or silicon dioxide on the side of the magnesium reflective layer 2 away from the base layer 1 and wrapping the sidewall of the metal film, forming a protective layer 3 with a thickness ranging from 30 to 150 nm. This ensures that the magnesium metal forming the magnesium reflective layer 2 is completely wrapped, preventing the magnesium metal from reacting with oxygen, carbon dioxide, or water in the air during use, which would cause the magnesium reflective layer 2 to fail.

[0019] like Figure 2As shown, the preparation method includes the following steps: S1 Substrate preparation: The substrate surface is cleaned and dried to obtain a clean substrate layer 1. Specifically, a 30*30mm BF33 or SK-1300 glass blank is selected as the mirror blank. The mirror blank is immersed in ethanol or deionized water and cleaned by ultrasonication. After cleaning, the mirror blank is dried with nitrogen gas to obtain a clean substrate layer 1; S2 Vacuum environment: The mirror blank obtained in S1 and the coating material are placed in a high vacuum coating machine, and the vacuum chamber is evacuated to 9*10 mm. -6 -5*10 -2 Pa; S3 coating: Magnesium reflective layer 2 and protective layer 3 are sequentially deposited on the substrate surface using a high-vacuum coating machine. Specifically, S3 coating includes S31 heating, S32 deposition of magnesium reflective layer 2, and S33 deposition of protective layer 3. S31 heating: The evaporation boat is heated to room temperature -1500℃, and the substrate temperature is controlled at room temperature -300℃. S32 deposition of magnesium reflective layer 2: The distance between the evaporation boat and the substrate is controlled to be 100-700mm, the substrate stage rotation is controlled to be ≤25r / min, magnesium ingots are placed in the evaporation boat to obtain magnesium vapor, and magnesium vapor is obtained through electron beam heating technology. The generation rate of magnesium vapor is controlled, thereby controlling the deposition rate of the magnesium metal coating to be between 0.01 nm / s and 999 nm / s, so that magnesium vapor is deposited on the substrate surface to obtain a magnesium reflective layer 2 with a thickness between 80 and 10000 nm. In this embodiment, the thickness of the metallic magnesium in the magnesium reflective layer is 200 nm. S33 Protective layer 3 deposition: Under the condition of not destroying the vacuum, at least one of magnesium fluoride, aluminum oxide or silicon dioxide is deposited on the surface of the magnesium reflective layer 2 by in-situ deposition using PECVD method to obtain a protective layer 3 with a thickness between 30 and 150 nm.

[0020] To demonstrate the reflectivity of the optical element prepared by this method for light with wavelengths less than 400nm, an optical element with vacuum-deposited aluminum film was used as a control group. The reflectivity of the optical element prepared by this method for light with wavelengths less than 400nm was tested. The preparation process of the control group optical element was basically the same as that of this method, except that magnesium ingots were replaced with aluminum ingots. The test results are shown in Table 1.

[0021] Table 1

[0022] As shown in Table 1, when the wavelength is less than 400 nm, the reflectivity of optical elements based on magnesium-based reflective layers is better than that of optical elements based on aluminum-based reflective layers.

[0023] In addition, to verify the reliability of the optical components prepared by this method during use, the prepared optical components were subjected to durability tests through salt spray test and damp heat test. The results showed that after 500 hours, the reflectivity decay was <5%, proving that the method has high reliability and certain practical novelty.

[0024] Example 2 Example 2 is basically the same as Example 1, except that, as Figure 3 As shown, the protective layer 3 has a double-layer structure, comprising a dense layer 31 and a wear-resistant layer 32. One side of the dense layer 31 is attached to the surface of the magnesium reflective layer 2 and serves as a support for the wear-resistant layer 32, which is attached to the surface of the dense layer 31. In this embodiment, the dense layer 31 is made of alumina with a thickness of not less than 20 nm. The alumina is attached to the surface of the magnesium reflective layer 2 to prevent the magnesium reflective layer 2 from contacting the external environment. The wear-resistant layer 32 is made of silicon dioxide with a thickness of not less than 80 nm. The silicon dioxide covers the surface of the dense layer 31 to protect it, thereby preventing wear on the dense layer 31 during use and ensuring the lifespan of the internal magnesium reflective layer 2.

[0025] Example 3 Example 3 is basically the same as Example 1, except that, in order to adapt to more scenario requirements and improve the application range of magnesium metal reflective layer, the material of substrate layer 1 can also be a nano metal film with a light transmittance of more than 80%, acrylic, polycarbonate or ceramic.

[0026] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that the technical means for solving problems in the above embodiments of the present invention can be used in combination to solve multiple technical problems simultaneously. For those skilled in the art, several modifications and improvements can be made without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. High reflectivity optical element based on a magnesium-based reflective layer, characterized in that: The substrate layer is selected from a material with a light transmittance of greater than 80% for light with a wavelength of less than 400 nm, and the surface of the substrate layer is sequentially attached with a magnesium reflection layer and a protective layer, wherein the magnesium reflection layer is formed by deposition of metallic magnesium under vacuum plating process, and the protective layer is deposited on the surface of the magnesium reflection layer and protects the magnesium reflection layer.

2. The high-reflectivity optical element based on a magnesium-based reflective layer according to claim 1, characterized in that: The thickness of the magnesium reflection layer is between 80-10000 nm.

3. The high reflectivity optical element based on a magnesium-based reflector layer according to claim 2, characterized in that: The material of the protective layer is at least one of magnesium fluoride, aluminum oxide or silicon dioxide, and the thickness range is 30-150 nm.

4. The high-reflectivity optical element based on a magnesium-based reflective layer according to claim 3, characterized in that: The protective layer has a double-layer structure, including a dense layer and a wear-resistant layer, the dense layer is attached to the surface of the magnesium reflection layer and serves as a support for the wear-resistant layer, and the wear-resistant layer is attached to the surface of the dense layer.

5. The high reflectivity optical element based on magnesium-based reflection layer according to claim 4, wherein: The material of the dense layer is aluminum oxide, and the thickness of the aluminum oxide is not less than 20 nm, and the material of the wear-resistant layer is silicon dioxide, and the thickness of the silicon dioxide is not less than 80 nm.

6. The high reflectivity optical element based on magnesium-based reflection layer according to claim 5, wherein: The substrate layer is selected from one of soda-lime glass, quartz glass, borosilicate glass or optical glass.

7. The high reflectivity optical element based on magnesium-based reflective layer according to claim 1, wherein: The material of the substrate layer can be one of nanometer metal film, glass, acrylic, polycarbonate, quartz or ceramic.

8. The high-reflectivity optical element based on a magnesium-based reflective layer according to claim 5 or 6, characterized in that: The manufacturing method comprises the following steps: S1, substrate preparation, cleaning and drying the surface of the substrate to obtain a clean substrate layer; S2, vacuum environment, placing the substrate obtained in S1 and plating raw materials into a high-vacuum plating machine, and vacuumizing the vacuum chamber to 9*10 -6 -5*10 - 2 Pa; S3, plating, sequentially depositing the magnesium reflection layer and the protective layer on the surface of the substrate by the high-vacuum plating machine.

9. The high reflectivity optical element based on a magnesium-based reflector layer according to claim 8, characterized in that: The S3 plating film includes S31 heating, S32 magnesium reflection layer deposition and S33 protective layer deposition, wherein S31 heating: heating the evaporation boat to room temperature-1500 DEG C, and controlling the substrate temperature to be room temperature-300 DEG C; S32 magnesium reflection layer deposition: controlling the distance between the evaporation boat and the substrate to be 100-700 mm, controlling the substrate table rotation to be less than or equal to 25 r / min, controlling the deposition rate to be 0.01 nm / s-999 nm / s, putting magnesium ingot into the evaporation boat to obtain magnesium vapor, and making the magnesium vapor deposit on the surface of the substrate to obtain a magnesium reflection layer with a thickness of 80-10000 nm; and S33 protective layer deposition: under the condition of not damaging the vacuum, depositing at least one of magnesium fluoride, aluminum oxide or silicon dioxide on the surface of the magnesium reflection layer by PECVD method in situ to obtain a protective layer with a thickness of 30-150 nm.

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