High-reflection film suitable for deep ultraviolet visible light to infrared light and film coating method

Abstract

The invention discloses a high-reflection film suitable for deep ultraviolet visible light to infrared light and a coating method, the film layer structure of the high-reflection film sequentially comprises a substrate, a base coat, a silver film, a protective layer and a medium reflection film stack from bottom to top, the medium reflection film stack is a reflection film stack which is composed of two materials of HfO2 and SiO2 and has the wave band of 200-400 nm, and the medium reflection film stack is a reflection film stack with the wave band of 200-400 nm. The film system structure of the medium reflecting film is a (LH) 10, b (LH) 10, c (LH) 10 and d (LH) 10, and a, b, c and d represent wavelength coefficient values of a film stack and meet the requirement of alt; blt; clt; ct; d; the film coating method comprises a normal-temperature film coating stage and a high-temperature film coating stage, the normal-temperature film coating comprises the film coating of a base coat, a silver film and a protective layer, and the high-temperature film coating comprises the film coating of a dielectric reflecting film stack; high-temperature coating is carried out on a product subjected to normal-temperature coating, SiO2 / HfO2 and Al2O3 / SiO2 film system structures are alternately evaporated by adopting a PVD thermal evaporation coating method, and the high-temperature coating temperature is 300 DEG C. According to the invention, high reflectivity can be realized from deep ultraviolet visible light to infrared light.

Description

Technical Field

[0001] This invention relates to the field of lens coating technology, and in particular to a high-reflectivity film and coating method suitable for deep ultraviolet, visible light to infrared light. Background Technology

[0002] High-reflectivity coatings in the ultraviolet to infrared long-wavelength range are commonly achieved using two processes: metal plating and dielectric coating. All-dielectric coatings require numerous layers, sometimes hundreds, leading to significant stress that can cause substrate deformation and coating cracking. Furthermore, the process suffers from poor stability and repeatability, making it unsuitable for optical lens manufacturing. Aluminum coatings have an average reflectivity of only around 90%, insufficient for the high reflectivity requirements of optical systems. Therefore, silver plating is used to improve overall reflectivity. However, silver exhibits significant absorption in the ultraviolet 205-400nm range, making it unsuitable as a coating material for ultraviolet mirrors. Therefore, a high-reflectivity coating is needed that can achieve high reflectivity across the deep ultraviolet, visible, and infrared light spectrum. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a high-reflectivity film and coating method applicable to deep ultraviolet-visible light to infrared light, which can achieve high reflectivity in deep ultraviolet-visible light to infrared light.

[0004] Technical Solution: To achieve the above objectives, the present invention provides a high-reflectivity film suitable for deep ultraviolet-visible light to infrared light. The film structure, from bottom to top, includes: a substrate, a base layer, a silver film, a protective layer, and a dielectric reflective film stack. The dielectric reflective film stack is a reflective film stack in the 230–400 nm wavelength band composed of three materials: SiO2 / HfO2 and Al2O3 / SiO2. The dielectric reflective film system structure is: a(LH) 10 b(LH) 10 c(LH) 10 and d(LH) 10 Where a, b, c, and d represent the wavelength coefficient values ​​of the membrane stack, satisfying a <b<c<d。

[0005] Preferably, the substrate is glass, crystal, single-crystal silicon, or silicon carbide.

[0006] Preferably, the substrate is metallic Cr, with a film thickness of 15~25nm and an evaporation rate of 1~3A / S.

[0007] Preferably, the silver film thickness is 90~140nm and the evaporation rate is 20~30A / S.

[0008] Preferably, the protective layer is made of Al2O3 and SiO2 materials.

[0009] Preferably, the Al2O3 film thickness is 10~30nm and the evaporation rate is 2~4A / S.

[0010] Preferably, the SiO2 film thickness is 10~25nm and the evaporation rate is 2~4A / S.

[0011] The coating method for high-reflectivity films applicable to deep ultraviolet, visible light, and infrared light according to the present invention includes a room temperature coating stage and a high temperature coating stage. The room temperature coating includes coating of an underlayer, a silver film, and a protective layer. The high temperature coating includes coating of a dielectric reflective film stack. On the product after the room temperature coating is completed, the high temperature coating uses a PVD thermal evaporation coating method to alternately deposit the dielectric reflective film structure. The high temperature coating temperature is 300°C.

[0012] Preferably, the protective layer is formed by first depositing an Al2O3 layer on top of the silver film, and then depositing a SiO2 layer. When depositing the SiO2 layer, a hollow cathode ion-assisted coating is used, with an ion source voltage of 150~200V, a current of 3~5A, and a gas concentration of 20~30sccm.

[0013] Beneficial effects: The present invention has the following advantages: 1. Using a silver film as the base layer can effectively improve the reflectivity from visible light to infrared; stacking SiO2 / HfO2 and Al2O3 / SiO2 dielectric films can preferentially improve the reflectivity from 200 to 400 nm, thereby achieving the high reflectivity requirement across the entire wavelength range from deep ultraviolet to infrared; 2. Utilizing the polarization-maintaining characteristics of the silver film, the separation between P-light and S-light reflection is small, which is beneficial to the transmission of light in the optical system and reduces the loss of polarized light. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the high-reflectivity film structure.

[0015] Figure 2 This is a measured reflectance curve of the high-reflectance film described in this invention within the wavelength range of 200~1000nm;

[0016] Figure 3 This is a reflectance curve of a product coated using existing conventional processes. Detailed Implementation

[0017] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0018] like Figure 1 As shown, the high-reflectivity film of the present invention comprises, from bottom to top, a substrate, a base layer, a silver film, a protective layer, and a dielectric reflective film stack.

[0019] Among them, the substrate is glass, crystal, single crystal silicon or silicon carbide. The underlayer is metal Cr, and the protective layer is aluminum oxide AL2O3 and silicon dioxide SiO2. The dielectric reflective film stack is a reflective film stack in the 200-400 nm band composed of three materials: SiO2 / HfO2 and Al2O3 / SiO2, and the film system structure is a(LH) 10 , b(LH) 10 , c(LH) 10 and d(LH) 10 , where a, b, c, and d represent the wavelength coefficient values of the film stack, satisfying a < b < c < d, and 10 represents the number of stacking periods.

[0020] Depositing a chromium film, a silver film and a dielectric protective layer on the substrate can achieve high reflection from the visible light to the infrared band; depositing a long-wave pass dielectric reflective film stack on the basis of the silver film can achieve a high reflection effect in the ultraviolet band.

[0021] Based on the film layer structure of the high-reflection film, the coating method of the present invention adopts two vacuum coating methods, namely room-temperature coating technology and high-temperature coating technology, which are carried out in two different stages respectively. Taking the H-K9L substrate as an example, the coating process is as follows:

[0022] 1. After ultrasonic cleaning (1 / 2 tank of alkaline cleaning agent, 3-9 tanks of pure water cleaning and slow pulling drying) of the substrate and the accompanying plating piece, put them into a vacuum coating machine (Xingnan vacuum coating machine) for room-temperature coating. The coating temperature is room temperature, and the vacuum degree is 2.0e -4 . Before coating, pre-cleaning is carried out by a hollow cathode ion source. Select a hollow cathode ion source, with a voltage of 200V, a current of 5A, and oxygen is charged and bombarded for 3-5 minutes.

[0023] The room-temperature coating includes: the first layer of chromium Cr, the second layer of silver Ag, the third layer of Al2O3, and the fourth layer of SiO2. When coating the fourth layer, a hollow cathode ion-assisted coating is required, with an ion source voltage of 200V, a current of 5A, and a gas flow of 30 sccm.

[0024] 2. After the room-temperature coating is completed, take out the product, wipe the surface clean, and put it back into the vacuum coating machine for high-temperature coating (because the silver film cannot be heated, so the product needs to be taken out and then continue to coat the dielectric film). The coating temperature is 250-300 °C. The coating process adopts the PVD thermal evaporation coating method to alternately evaporate the film system structures of SiO2 / HfO2 and Al2O3 / SiO2. After the coating is completed, cool for 3 hours and then open the door after entering the air, and take out the product.

[0025] Such as Figure 2As shown, the measured reflectance of the coated product in this embodiment is within the wavelength range of 200~1000nm (different colored curves in the figure represent p-light and s-light reflection at different angles). Within the wavelength range of 200~400nm, the reflectance is above 90%, and within the wavelength range of 400~1000nm, the reflectance reaches above 96%. Figure 3 The figure shows the reflectance curve of existing conventional coating products. The reflectance is extremely low in the wavelength range of 200~350nm, and it is impossible to achieve high reflectance in the deep ultraviolet-visible light to infrared light range.

Claims

1. A high reflectance film suitable for deep UV visible to infrared characterized in that, The film layer structure of the high reflection film comprises, from bottom to top, a substrate, a primer layer, a silver film, a protective layer, and a dielectric reflection film stack. The dielectric reflection film stack is selected from a reflection film stack of 200-400 nm wavelength band composed of SiO2 / HfO2 and Al2O3 / SiO2 three materials, and the dielectric reflection film system structure is a(LH)^10, b(LH)^10, c(LH)^10 and d(LH)^10, wherein a, b, c, d represent the wavelength coefficient value of the film stack, and satisfy a 2. The high reflectivity film of claim 1, wherein The substrate is glass, crystal, monocrystalline silicon or silicon carbide.

3. The high reflectivity film of claim 1, wherein The primer layer is a metal Cr material, the film thickness is 15-25 nm, and the evaporation rate is 1-3 A / S.

4. The high reflectivity film of claim 1, wherein The silver film thickness is 90-140 nm, and the evaporation rate is 20-30 A / S.

5. The high reflectivity film of claim 1, wherein The protective layer is an Al2O3 and SiO2 material.

6. The high reflectivity film of claim 5, wherein, The Al2O3 film thickness is 10-30 nm, and the evaporation rate is 2-4 A / S.

7. The high reflectivity film of claim 5, wherein The SiO2 film thickness is 10-25 nm, and the evaporation rate is 2-4 A / S.

8. A coating method suitable for the high reflection film for deep ultraviolet to infrared according to claim 1, characterized by, The process comprises a normal temperature plating film stage and a high temperature plating film stage. The normal temperature plating film comprises the plating of the primer layer, the silver film and the protective layer, and the high temperature plating film comprises the plating of the dielectric reflection film stack. The high temperature plating film is alternately evaporated on the product after the normal temperature plating film by using the PVD thermal evaporation plating film method, the film system structure of the dielectric reflection film stack, and the high temperature plating film temperature is 300℃.

9. The coating method according to claim 8, wherein The protective layer plating film is plated on the silver film, and the Al2O3 layer is plated first, and then the SiO2 layer is plated. The hollow cathode ion assisted plating film is used when the SiO2 layer is plated, the ion source voltage is 150-200 V, the current is 3-5 A, and the gas is 20-30 sccm.

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