Dichroic mirror optical film and method of coating the same

Abstract

The application provides a kind of dichroic mirror optical film and its plating method, the dichroic mirror optical film, low refractive index material is selected with excellent laser resistance SiO2, high refractive index material is selected with very high refractive index Ta2O5 and deep ultraviolet low absorption metal Hf.Through the refractive index ratio of Ta2O5-SiO2 film stack in the whole film layer structure inside, that is, the part of smaller reflection absorption, the advantage of using the refractive index ratio is large to achieve the requirement of high reflectivity by less film layer number;Hf-SiO2 film stack is superimposed in the outermost part of Ta2O5-SiO2 film stack, not only can ensure that the reflectivity of deep ultraviolet band meets the standard, but also plays a half-wave protection role for Ta2O5-SiO2 to improve its laser damage capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, in particular to a dichroic mirror optical film and a plating method thereof. BACKGROUND

[0002] Dichroic mirror is a special optical element, which can selectively transmit certain wavelengths of light and reflect other wavelengths of light. This characteristic makes dichroic mirror widely used in various optical systems. In order to simultaneously achieve the requirements of high reflectivity of dichroic mirror to deep ultraviolet and high transmittance to near infrared, the design of high-performance beam splitting film, i.e. dichroic mirror optical film, needs to meet the following principles: one is to select a material combination with large difference between high and low refractive indices, reduce the number of plated film layers, and reduce the difficulty of preparation and production cost; two is from the perspective of the spectral curve of the film, the film layer material should have very small absorption performance in deep ultraviolet to ensure its reflectivity.

[0003] Considering the refractive index difference of the high and low refractive index materials that can be achieved and the absorption problem of deep ultraviolet, the high refractive index materials that can be selected are very limited. For example, tantalum pentoxide (Ta2O5), titanium dioxide (TiO2), and niobium pentoxide (Nb2O5) are generally low-melting-point materials, which have relatively large absorption rate in deep ultraviolet, and the energy accumulation during laser irradiation has obvious ablation effect on the film. High refractive index materials with low absorption rate in deep ultraviolet, such as hafnium dioxide (HfO2), aluminum trioxide (Al2O3), and calcium fluoride (CaF2), have low refractive index, and have the disadvantages of large number of layers required to achieve high reflectivity, rough film surface, high cost, and difficulty in plating. Therefore, an effective solution is urgently needed to solve the above problems. SUMMARY

[0004] The present application provides a dichroic mirror optical film and a plating method thereof, which solves the defects of large number of layers required, rough film surface, difficulty in plating, easy to peel off, and high cost in the prior art, and realizes that high reflectivity and high damage threshold can be achieved with fewer film layers.

[0005] The present application provides a dichroic mirror optical film, which is composed of a tantalum pentoxide film layer, a silicon dioxide film layer, and a metal hafnium film layer plated on a dichroic mirror.

[0006] According to the dichroic mirror optical film provided by the present application, the dichroic mirror includes a first plating surface and a second plating surface.

[0007] The dichroic mirror optical film includes a beam splitting film plated on the first plating surface and an anti-reflection film plated on the second plating surface.

[0008] The light splitting film is composed of the tantalum pentoxide film layer, the silicon dioxide film layer and the metal hafnium film layer.

[0009] The antireflection film is composed of the silicon dioxide film layer and the metal hafnium film layer.

[0010] The light splitting film is composed of a long-wave pass film system and a high reflection film.

[0011] The long-wave pass film system is composed of the tantalum pentoxide film layer and the silicon dioxide film layer.

[0012] The high reflection film is composed of the silicon dioxide film layer and the metal hafnium film layer.

[0013] The light splitting film is composed of a long-wave pass film system and a high reflection film.

[0014] The antireflection film comprises at least one silicon dioxide film layer and at least one metal hafnium film layer which are sequentially plated on the second plating surface; the first film layer plated on the second plating surface is a silicon dioxide film layer.

[0015] The application further provides a plating method for the dichroic mirror optical thin film.

[0016] The base film layer of the dichroic mirror is etched by using a Hall ion source for 10-15 minutes, and the background vacuum degree is kept below 2*10 -3 Pascal, and the deposition temperature is 150-200 degrees Celsius, and the constant temperature is kept for 10-20 minutes.

[0017] The dichroic mirror optical thin film composed of the tantalum pentoxide film layer, the silicon dioxide film layer and the metal hafnium film layer is plated on the surface of the dichroic mirror.

[0018] The application provides a plating method for a dichroic mirror optical thin film.

[0019] The dichroic mirror optical thin film composed of the tantalum pentoxide film layer, the silicon dioxide film layer and the metal hafnium film layer is plated on the surface of the dichroic mirror.

[0020] The long-wave pass film system and the high reflection film are sequentially plated on the first plating surface.

[0021] The antireflection film is plated on the second plating surface.

[0022] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0023] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0024] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0025] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0026] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0027] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0028] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0029] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0030] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0031] The coating method of the dichroic mirror optical film comprises the following steps: coating a long-wave pass film system on a first coating surface of a substrate, and coating a high reflection film on a second coating surface of the substrate.

[0032] The deposition rate is controlled to be 0.5-0.6 nm / s during plating the silica film layer in the antireflection film, and an ion source is used to assist evaporation of the first silica film layer, and an electron gun is used to assist evaporation of the other silica film layers.

[0033] The plating method of the dichroic mirror optical film further comprises the following steps before plating the long-wave pass film system and the high-reflection film on the first plating surface in sequence:

[0034] Obtaining a plating proportion parameter and a plating target corresponding to the dichroic mirror;

[0035] According to the plating target and the plating proportion parameter, target plating thicknesses of each tantalum pentoxide film layer in the light-splitting film, target plating thicknesses of each silica film layer, and target plating thicknesses of each hafnium film layer are determined respectively.

[0036] According to the target plating thicknesses of each silica film layer in the long-wave pass film system, the plating target, and the plating proportion parameter, target plating thicknesses of each silica film layer in the antireflection film and target plating thicknesses of each hafnium film layer are determined respectively.

[0037] The plating method of the dichroic mirror optical film further comprises the following steps before plating the long-wave pass film system and the high-reflection film on the first plating surface in sequence:

[0038] The sum of the target plating thicknesses of each silica film layer in the long-wave pass film system is calculated to obtain the target plating thickness of the first silica film layer in the antireflection film.

[0039] According to the target plating thickness of the first silica film layer, the plating target, and the plating proportion parameter, target plating thicknesses of each other silica film layer in the antireflection film and target plating thicknesses of each hafnium film layer are determined respectively, the other silica film layer being any silica film layer in the antireflection film except the first silica film layer.

[0040] The dichroic mirror optical film and the plating method thereof provided by the application use three kinds of film materials, the low refractive index material is SiO2 with excellent laser resistance, the high refractive index material is Ta2O5 with high refractive index and metal Hf with low deep ultraviolet absorption. The Ta2O5-SiO2 film stack is used in the inner part of the whole film layer structure, i.e. the part with small reflection absorption, and the high reflectivity requirement is achieved by using the large refractive index ratio advantage of the Ta2O5-SiO2 film stack and less film layers; the Hf-SiO2 film stack is superimposed on the outermost part of the Ta2O5-SiO2 film stack, and the reflectivity of the deep ultraviolet band is ensured to meet the standard, and the Hf-SiO2 film stack combination has strong laser damage resistance to ensure the laser resistance of the whole film layer, and the Ta2O5-SiO2 has a half-wave protection effect to improve the laser damage resistance. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0042] Figure 1 It is a flowchart of the plating method of the dichroic mirror optical film provided by the application.

[0043] Figure 2 It is a size schematic diagram of the dichroic mirror provided by the application.

[0044] Figure 3 It is a spectral curve diagram of the residual reflectivity of the dichroic mirror at 29° incident angle provided by the application.

[0045] Figure 4 It is a spectral curve diagram of the residual reflectivity of the dichroic mirror at 61° incident angle provided by the application.

[0046] Figure 5 It is a spectral curve diagram of the residual reflectivity of the dichroic mirror at 29° incident angle provided by the application.

[0047] Figure 6 It is a spectral curve diagram of the residual reflectivity of the dichroic mirror at 50° incident angle provided by the application.

[0048] Figure 7 It is a spectral curve diagram of the residual reflectivity of the dichroic mirror at 61° incident angle provided by the application.

[0049] Figure 8 It is a spectral curve diagram of the residual reflectivity and transmittance of the dichroic mirror at 29-61° incident angle provided by the application.

[0050] Figure 9 is a spectral curve of the residual reflectivity of the dichroic mirror 29-61° incident angle provided by the present application. DETAILED DESCRIPTION

[0051] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described below in conjunction with the accompanying drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0052] The following will be described in conjunction with Figures 1-9 The dichroic mirror optical film and the plating method thereof of the present application are described.

[0053] In order to facilitate a clearer understanding of the technical solutions of the embodiments of the present application, first, some technical contents related to the embodiments of the present application are introduced.

[0054] Hafnium is a metal element, symbol Hf, atomic number 72, atomic weight 178.49.

[0055] Silicon dioxide is an inorganic compound, chemical formula SiO2. Silicon dioxide has a very small absorption coefficient at the working wavelength, grows uniformly in microparticles, the film layer structure is amorphous, has a high laser damage threshold, and is an ideal low refractive index material.

[0056] Tantalum pentoxide is a white colorless crystalline powder, which is the most common oxide of tantalum and the final product of tantalum burning in air, and the chemical formula is Ta2O5.

[0057] Vacuum evaporation: abbreviated as evaporation, refers to the process method of evaporating and vaporizing the film material (or film material) by using a certain heating evaporation method under vacuum conditions, and the particles fly to the substrate surface to condense into a film. Evaporation is an early and widely used gas deposition technology, which has the advantages of simple film forming method, high film purity and compactness, unique film structure and performance, etc.

[0058] Coated film fixture: plays the role of carrying optical elements in the vacuum evaporation process of optical elements, such as planetary clamps. Unlike optical elements, the material of the coated film fixture is usually a metal material, such as aluminum alloy, stainless steel, etc.

[0059] The working principle of the dichroic mirror is based on the thin film interference effect. By depositing multiple layers of thin films with different refractive indices on glass or other transparent substrates, a complex optical interference system is formed. When light is incident on such a multilayer film structure, different wavelengths of light will be partially or completely reflected due to interference, while other wavelengths of light will pass through the lens.

[0060] With the development of technology, especially driven by the demand in the fields of laser technology, optical communication, and biomedical science, the research and application of dichroic mirrors have been rapidly developed. For example, in laser technology, dichroic mirrors can be used for output coupling of lasers; in optical communication, dichroic mirrors can be used for separation of optical signals. In addition, the Thin Film Optical Laboratory of the Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences proposed a new design method for dichroic mirrors based on hybrid film layers and sandwich-like structure interfaces, which realized the preparation of dichroic mirrors with excellent spectral performance and high laser damage threshold at two wavelengths.

[0061] Dichroic mirrors have a wide range of applications in various fields:

[0062] Biomedical field: In fluorescence microscope systems, dichroic mirrors are used to separate excitation light and fluorescence signals, improving the clarity and contrast of fluorescence images.

[0063] Spectral analysis: As a spectroscopic element, dichroic mirrors are used in spectrometers to separate light sources into different spectral components for spectral analysis.

[0064] Stage lighting: In stage lighting systems, dichroic mirrors are used to achieve color separation, mixing, and adjustment, enhancing the visual effects of stage lighting.

[0065] Laser technology: Dichroic mirrors can be used as components for selecting specific wavelength laser outputs in lasers.

[0066] Optical filtering: In optical communication and spectral analysis, dichroic mirrors are used to filter out or select specific wavelength optical signals.

[0067] High-power laser beam combining: Dichroic mirror beam combining technology can relax the linewidth requirement of sub-beam lasers to several nanometers, requiring fewer optical elements, convenient optical path arrangement, compact structure, and easy integration. With the development of coating technology, the power handling capacity and steepness of dichroic mirrors have been greatly improved, which can meet the requirements of thousands to tens of thousands of watts of laser beam combining.

[0068] Embodiments of the present application provide a dichroic mirror optical film, which is composed of a Ta2O5 film layer, a SiO2 film layer, and a metal Hf film layer coated on a dichroic mirror. i O2 film layer, and a metal Hf film layer.

[0069] Among them, the dichroic mirror optical film is mainly a dichroic mirror film required for a large-angle film system in the ultraviolet-visible-near-infrared band. The dichroic mirror optical film adopts a G|Ta2O5-SiO2-Hf-SiO2|A multi-material film system structure, wherein G is a substrate, and A is air.

[0070] Specifically, the dichroic mirror optical thin film comprises at least one Ta2O5 film layer, at least one SiO2 film layer and at least one metal Hf film layer. i O2 film layer and at least one metal Hf film layer.

[0071] The dichroic mirror optical thin film provided by the embodiment of the present application does not use two traditional high and low refractive index thin film materials, but uses three thin film materials, the low refractive index material is SiO2 (refractive index n=1.465) with excellent laser resistance, the high refractive index material is Ta2O5 (n=2.2) with high refractive index and metal Hf (n=1.9) with deep ultraviolet low absorption. The Ta2O5-SiO2 film stack is used in the inner side of the whole film layer structure, that is, the part with small reflection and absorption, and the high reflectivity requirement is met by the large refractive index ratio and less film layers; the Hf-SiO2 film stack is superimposed on the outermost part of the Ta2O5-SiO2 film stack, so as to ensure that the reflectivity of the deep ultraviolet band meets the standard, the Hf-SiO2 film stack combination has strong laser damage resistance to ensure the laser damage resistance of the whole film layer, and the Ta2O5-SiO2 has a half-wave protection effect to improve the laser damage capacity, and the high reflectivity and high damage threshold requirement can be met by using less film layers.

[0072] In one or more optional embodiments of the present application, the dichroic mirror comprises a first plating surface and a second plating surface; the dichroic mirror optical thin film comprises a light splitting film plated on the first plating surface and an anti-reflection film plated on the second plating surface; the light splitting film is composed of the Ta2O5 film layer, the SiO2 film layer and the metal Hf film layer; and the anti-reflection film is composed of the SiO2 film layer and the metal Hf film layer.

[0073] Specifically, the dichroic mirror comprises two plating surfaces: a first plating surface and a second plating surface, and the dichroic mirror can be a plane mirror.

[0074] In actual application, the dichroic mirror optical thin film comprises a light splitting film and an anti-reflection film, and the light splitting film and the anti-reflection film are plated on the two plating surfaces of the dichroic mirror, that is, the light splitting film is plated on one plating surface, and the anti-reflection film is plated on the other plating surface.

[0075] The light splitting film is composed of at least one Ta2O5 film layer, at least one SiO2 film layer and at least one metal Hf film layer; and the anti-reflection film is composed of at least one SiO2 film layer and at least one metal Hf film layer alternately stacked.

[0076] The dichroic mirror optical film provided by the embodiment of the present application has the advantages that the low reflection and absorption of the antireflection film is used, the high reflectivity is achieved by the less film layers due to the large refractive index ratio, the strong laser damage resistance of the dichroic mirror optical film is further achieved to ensure the laser damage resistance of the whole film layer, the half-wave protection effect of improving the laser damage resistance is achieved, and the high reflectivity and high damage threshold are achieved by the less film layers.

[0077] In one or more optional embodiments of the present application, the light splitting film is composed of a long-wave pass film system and a high reflection film; the long-wave pass film system is composed of the Ta2O5 film layer and the SiO2 film layer; and the high reflection film is composed of the SiO2 film layer and the metal Hf film layer.

[0078] In practical application, the long-wave pass film system greater than 330 nm (usually 330 nm-1500 nm) is made by using the characteristics of the film materials Ta2O5 and SiO2, and then the high reflection film of 250 nm-330 nm is made by using the characteristics of the film materials metal Hf and SiO2. In this way, the dichroic mirror optical film can be ensured, and the high reflectivity and high damage threshold can be achieved by the less film layers.

[0079] In one or more optional embodiments of the present application, the light splitting film is sequentially composed of at least one long-wave pass film system and at least one high reflection film from the first plating surface to the second plating surface; the antireflection film includes at least one SiO2 film layer and at least one metal Hf film layer which are sequentially and alternately plated on the second plating surface; and the first film layer plated on the second plating surface is the SiO2 film layer.

[0080] Specifically, the light splitting film adopts a structure of G|0.88(0.5L M 0.5L)^16 0.79(HL)^12 0.67(HL)^110.58(HL)^11 0.49(HL)^11|A, the center wavelength is 550 nanometers (nm), M is the high refractive index material Ta2O5, H is the high refractive index material metal Hf, L is the low refractive index material SiO2, (0.5L M 0.5L)^S is a classic long-wave pass film system (Ta2O5-SiO2 film stack), (HL)^S is a classic high reflection film (Hf-SiO2 film stack), 0.88 is a proportion factor of the long-wave pass film system, 16 is a stack number of the long-wave pass film system, 0.5 is a proportion factor of the SiO2 film layer in the long-wave pass film system, 0.79, 0.67, 0.58 and 0.49 are respectively proportion factors of each high reflection film, and 12, 11, 11 and 11 are respectively stack numbers of each high reflection film.

[0081] The dichroic mirror optical film provided by the embodiment of the present application does not use traditional two high and low refractive index film materials, but uses three film materials, the low refractive index material is selected from SiO2 (refractive index n=1.465) with excellent laser resistance, the high refractive index material is selected from Ta2O5 (n=2.2) with high refractive index and metal Hf (n=1.9) with low deep ultraviolet absorption. The Ga|Ta2O5-SiO2-Hf-SiO2|A film system structure is adopted, the Ta2O5-SiO2 film stack is used in the inner side of the whole film layer structure, i.e. the part with small reflection and absorption, the high reflectivity requirement is met by using the large refractive index ratio advantage of the Ta2O5-SiO2 film stack through fewer film layers; the Hf-SiO2 film stack is superimposed on the outermost part of the Ta2O5-SiO2 film stack, the reflectivity of the deep ultraviolet band is ensured to meet the standard, the Hf-SiO2 film stack has strong laser damage resistance to ensure the laser resistance of the whole film layer, the laser damage resistance of the Ta2O5-SiO2 is improved by the half-wave protection of the Hf-SiO2 film stack, and the requirements of high reflectivity and high damage threshold can be met by using fewer film layers.

[0082] Figure 1 The present application provides a plating method for the dichroic mirror optical film, as shown in Figure 1 The method comprises steps 101 and 102.

[0083] Step 101: etching the base film layer of the dichroic mirror using a Hall ion source for 10-15 minutes (min), and keeping the background vacuum degree below 2*10 -3 Pa, and the deposition temperature is 150-200 degrees Celsius (℃), and the constant temperature is kept for 10-20 min.

[0084] In actual application, in order to ensure the success rate of plating the dichroic mirror optical film, the dichroic mirror needs to be pretreated before plating. That is, before plating the dichroic mirror optical film, the previous base film layer needs to be etched using a Hall ion source for 10-15 min, and the background vacuum degree is kept below 2*10 -3 Pa before plating, the deposition temperature is 150-200℃, and the constant temperature is kept for 10-20 min.

[0085] Step 102: plating the dichroic mirror optical film composed of a Ta2O5 film layer, a SiO2 film layer and a metal Hf film layer on the surface of the dichroic mirror.

[0086] After the dichroic mirror is pretreated, the dichroic mirror can be fixed using a plating fixture, and then the Ta2O5 film layer, the SiO2 film layer and the metal Hf film layer, i.e. the dichroic mirror optical film, are plated on the surface of the dichroic mirror.

[0087] Among them, the plating of the dichroic mirror optical film can be carried out by ion source assisted deposition electron beam evaporation method or vacuum evaporation method.

[0088] In one or more optional embodiments of the present application, the dichroic mirror comprises a first plating surface and a second plating surface, the dichroic mirror optical film comprises a light splitting film plated on the first plating surface and an anti-reflection film plated on the second plating surface, and the light splitting film is composed of a long-wave pass film system and a high-reflection film; correspondingly, the dichroic mirror optical film plated on the surface of the dichroic mirror and composed of a Ta2O5 film layer, a SiO2 film layer and a metal Hf film layer comprises:

[0089] The long-wave pass film system and the high-reflection film are sequentially plated on the first plating surface;

[0090] The anti-reflection film is plated on the second plating surface.

[0091] In practical applications, the long-wave pass film system and the high-reflection film can be plated on the first plating surface of the dichroic mirror, and the anti-reflection film can be plated on the second plating surface, so as to ensure the integrity and accuracy of the optical characteristics of the dichroic mirror optical film.

[0092] In one or more optional embodiments of the present application, the long-wave pass film system is composed of the Ta2O5 film layer and the SiO2 film layer, and the high-reflection film is composed of the SiO2 film layer and the metal Hf film layer; correspondingly, the sequentially plating the long-wave pass film system and the high-reflection film on the first plating surface comprises:

[0093] When plating the Ta2O5 film layer in the long-wave pass film system, an ion source is used for auxiliary evaporation, and the deposition rate is controlled to be 0.2-0.3 nanometers per second (nm / s), and the oxygen charging amount is controlled to be 10-20 standard cubic centimeters per minute (SCCM); when plating the SiO2 film layer in the long-wave pass film system, an ion source is used for auxiliary evaporation, and the deposition rate is controlled to be 0.5-0.6 nm / s;

[0094] After the plating of the long-wave pass film system is completed, the plating of the high-reflection film is suspended for 10-20 minutes, and then the plating is resumed;

[0095] When plating the metal Hf film layer in the high-reflection film, an electron gun is used for auxiliary evaporation, and the deposition rate is controlled to be 0.06-0.08 nm / s, and the oxygen charging amount is controlled to be 60-80 SCCM; when plating the SiO2 film layer in the high-reflection film, an electron gun is used for auxiliary evaporation, and the deposition rate is controlled to be 0.5-0.6 nm / s.

[0096] In the Ta2O5-SiO2 combination (long-wave pass film system), Ta2O5 and SiO2 are respectively assisted by ion source for evaporation to ensure the firmness of the film layer. When plating Ta2O5 film layer, the deposition rate is controlled at 0.2-0.3 nm / s, the oxygen filling amount is 10-20 SCCM, and the film is formed by ion source assisted evaporation. When plating SiO2 film layer, the deposition rate is controlled at 0.5-0.6 nm / s, and the film is formed by ion source assisted evaporation.

[0097] After the Ta2O5-SiO2 combination plating is completed, a pause plating of about 10-20 min is arranged at the junction of SiO2 and Hf film layer (the last layer of film layer of long-wave pass film system is SiO2 film layer, and the first layer of film layer of high-reflection film is metal Hf film layer), to ensure the firmness of the substrate film layer when Hf is evaporated. In the Hf-SiO2 combination (high-reflection film), when plating each metal Hf film layer, the deposition rate is controlled at 0.06-0.08 nm / s, the oxygen filling amount is 60-80 SCCM, and the film is formed by electron gun evaporation. When plating SiO2 film layer, the deposition rate is controlled at 0.5-0.6 nm / s, and the film is formed by electron gun evaporation. Ion source is not used for assisted evaporation in this stage to prevent absorption phenomenon in deep ultraviolet wave band and affect the spectral curve.

[0098] In addition, since the high-reflection film is Hf-SiO2 combination, a pause plating of about 10-20 min also needs to be arranged at the junction of SiO2 and Hf film layer.

[0099] In one or more optional embodiments of the present application, the anti-reflection film is composed of the SiO2 film layer and the metal Hf film layer; accordingly, the plating of the anti-reflection film on the second plating surface comprises:

[0100] Plating a first layer of SiO2 film layer of the anti-reflection film on the second plating surface;

[0101] After the plating of the first layer of SiO2 film layer is completed, the plating of the metal Hf film layer and other SiO2 film layers of the anti-reflection film is paused for 10-20 minutes, and the other SiO2 film layers are any SiO2 film layer in the anti-reflection film except the first layer of SiO2 film layer;

[0102] When plating the metal Hf film layer in the anti-reflection film, electron gun is used for assisted evaporation, and the deposition rate is controlled at 0.06-0.08 nm / s, and the oxygen filling amount is 60-80 SCCM;

[0103] The deposition rate is controlled to be 0.5-0.6 SCCM, and the ion source is used to assist the evaporation of the first SiO2 film layer, and the electron gun is used to assist the evaporation of the other SiO2 film layers.

[0104] Due to the excessively large diameter-thickness ratio of the dichroic mirror, the first coating surface will have a great influence on the surface profile of the original element after coating the beam splitting film. In order to minimize the influence of the first coating surface on the surface profile after coating the beam splitting film, and the first coating surface generates a film layer with a large stress in the Ta2O5-SiO2 combination (long-wave pass film system) using an ion source, the ion source is used to assist the evaporation of the first layer (SiO2 film layer) during the coating of the second coating surface. After the first layer is completed, the coating is paused for about 10-20 minutes at the junction between the SiO2 and Hf film layers to ensure the firmness of the substrate film layer during Hf evaporation. In the Hf-SiO2 combination, the deposition rate is controlled to be 0.06-0.08 nm / s, the oxygen charge is 60-80 SCCM, and the film is formed by electron gun evaporation. When coating the SiO2 film layer, the deposition rate is controlled to be 0.5-0.6 nm / s, and the film is formed by electron gun evaporation.

[0105] In one or more optional embodiments of the present application, before the long-wave pass film system and the high-reflection film are sequentially coated on the first coating surface, the method further comprises:

[0106] Obtaining a coating proportion parameter and a coating target corresponding to the dichroic mirror;

[0107] According to the coating target and the coating proportion parameter, the target coating thickness of each Ta2O5 film layer in the beam splitting film, the target coating thickness of each SiO2 film layer, and the target coating thickness of each metal Hf film layer are determined respectively.

[0108] According to the target coating thickness of each SiO2 film layer in the long-wave pass film system, the coating target, and the coating proportion parameter, the target coating thickness of each SiO2 film layer in the antireflection film and the target coating thickness of each metal Hf film layer are determined respectively.

[0109] Specifically, the coating proportion parameter and the coating target corresponding to the dichroic mirror can be obtained first. Ta2O5, SiO2, and Hf can share one coating proportion parameter, or each can correspond to a respective coating proportion parameter. The coating proportion parameter can be pre-set or calculated according to actual conditions. The present application does not limit this.

[0110] Then, based on the plating target, simulation and analysis are performed to obtain the simulated plating thickness of each Ta2O5 film layer in the light-splitting film, the simulated plating thickness of each SiO2 film layer, and the simulated plating thickness of each metal Hf film layer. Then, the simulated plating thickness of each Ta2O5 film layer in the light-splitting film is multiplied by the corresponding plating proportion parameter to obtain the target plating thickness of each Ta2O5 film layer in the light-splitting film; the simulated plating thickness of each SiO2 film layer in the light-splitting film is multiplied by the corresponding plating proportion parameter to obtain the target plating thickness of each SiO2 film layer in the light-splitting film; and the simulated plating thickness of each metal Hf film layer in the light-splitting film is multiplied by the corresponding plating proportion parameter to obtain the target plating thickness of each metal Hf film layer in the light-splitting film.

[0111] Further, based on the target plating thickness of all SiO2 film layers in the long-wave-pass film system in the light-splitting film, the plating target, and the plating proportion parameter, simulation, analysis, and calculation are performed to obtain the target plating thickness of each SiO2 film layer in the antireflection film and the target plating thickness of each metal Hf film layer. Further, the long-wave-pass film system and the high-reflection film can be sequentially plated on the first plating surface according to the target plating thickness of each Ta2O5 film layer, the target plating thickness of each SiO2 film layer, and the target plating thickness of each metal Hf film layer; and the antireflection film can be plated on the second plating surface according to the target plating thickness of each SiO2 film layer and the target plating thickness of each metal Hf film layer.

[0112] It should be noted that the plating proportion parameter includes a plating proportion parameter of Ta2O5, a plating proportion parameter of SiO2, and a plating proportion parameter of Hf; and correspondingly, the process of obtaining the plating proportion parameter can be as follows:

[0113] A first lens, a second lens, and a third lens made of the same base material as the dichroic mirror are obtained.

[0114] A Ta2O5 film layer with a first set thickness is plated on the surface of the first lens, a SiO2 film layer with a second set thickness is plated on the surface of the second lens, and a metal Hf film layer with a third set thickness is plated on the surface of the third lens.

[0115] The simulated plating thickness of the Ta2O5 film layer on the second lens after plating is determined by simulation and analysis, the simulated plating thickness of the SiO2 film layer on the second lens after plating is determined by simulation and analysis, and the simulated plating thickness of the metal Hf film layer on the third lens after plating is determined by simulation and analysis.

[0116] The ratio of the first set thickness to the simulated plating thickness of the Ta2O5 film layer on the first lens is determined as the plating proportion parameter corresponding to the Ta2O5 film layer, the ratio of the second set thickness to the simulated plating thickness of the SiO2 film layer on the second lens is determined as the plating proportion parameter corresponding to the SiO2 film layer, and the ratio of the third set thickness to the simulated plating thickness of the metal Hf film layer on the third lens is determined as the plating proportion parameter corresponding to the metal Hf film layer.

[0117] Specifically, the first lens, the second lens and the third lens can be three identical plane mirrors. The first set thickness, the second set thickness and the third set thickness can be the same or different, wherein the first set thickness is the actual plating thickness of the Ta2O5 film layer on the first lens, the second set thickness is the actual plating thickness of the SiO2 film layer on the second lens, and the third set thickness is the actual plating thickness of the metal Hf film layer on the third lens. The first set thickness, the second set thickness and the third set thickness are 150-300 nanometers.

[0118] In one or more optional embodiments of the present application, the target plating thicknesses of the SiO2 film layers and the target plating thicknesses of the metal Hf film layers in the antireflection film are determined according to the target plating thicknesses of the SiO2 film layers in the long-wave-pass film system, the plating target and the plating proportion parameter, comprising:

[0119] The sum of the target plating thicknesses of the SiO2 film layers in the long-wave-pass film system is calculated to obtain the target plating thickness of the first SiO2 film layer in the antireflection film;

[0120] The target plating thicknesses of the other SiO2 film layers and the target plating thicknesses of the metal Hf film layers in the antireflection film are determined according to the target plating thickness of the first SiO2 film layer, the plating target and the plating proportion parameter, wherein the other SiO2 film layers are any SiO2 film layer in the antireflection film except the first SiO2 film layer.

[0121] In practical applications, the thickness of the first film layer (the first SiO2 film layer) in the antireflection film is the sum of the target plating thicknesses of all SiO2 film layers in the combination of Ta2O5 and SiO2 (the long-wave-pass film system).

[0122] Then, the ratio of the target plating thickness of the first SiO2 film layer to the plating proportion parameter is taken as the simulated plating thickness of the first SiO2 film layer, and simulation is performed based on the simulated plating thickness of the first SiO2 film layer and the plating target to obtain the simulated plating thicknesses of the other SiO2 film layers and the simulated plating thicknesses of the metal Hf film layers in the antireflection film.

[0123] Further, the simulated plating thicknesses of each other SiO2 film layer in the antireflection film are multiplied by the corresponding plating proportion parameters respectively to obtain the target plating thicknesses of each other SiO2 film layer in the antireflection film; the simulated plating thicknesses of each metal Hf film layer in the antireflection film are multiplied by the corresponding plating proportion parameters respectively to obtain the target plating thicknesses of each metal Hf film layer in the antireflection film.

[0124] The plating method of the dichroic mirror optical film provided by the application is further described below in combination with specific examples.

[0125] First, a dichroic mirror to be plated is obtained, referring to Figure 2 , Figure 2 is a size schematic diagram of the dichroic mirror provided by the application. According to the front view and the rear view of the dichroic mirror in Figure 2 , the lower half length and the upper half length of the dichroic mirror are both , the left half width is , and the right half width is ; the length is , and the thickness is 14.091 mm ±0.0150 , and the center thickness is 14.142 mm.

[0126] The dichroic mirror is plated with a light splitting film on the S1 surface, and the film system index is as follows: average reflectivity Ravg>96% @ 250-460 nm, 29-61 degrees (deg); average transmittance Tavg>90% @ 1050-1100 nm, 1200-1400 nm, 29-61 deg; the dichroic mirror is plated with an antireflection film on the S2 surface, and the film system index is as follows: Ravg<5% @ 250-650 nm, 1050-1100 nm, 1200-1400 nm, 29-50 deg; Ravg<10% @ 250-650 nm, 1050-1100 nm, 1200-1400 nm, 50-61 deg. As known above, S1 requires to ensure 96% average residual reflectivity under the requirements of deep ultraviolet and large angle, and to ensure 90% average transmittance under the requirements of near infrared and large angle; S2 requires to ensure a certain residual reflectivity under the requirements of deep ultraviolet, near infrared and large angle.

[0127] The light splitting film is plated on the S1 surface, including the film system design aspect and the process preparation aspect.

[0128] The film system design aspect: according to the film system index, a G| Ta2O5-SiO2-Hf-SiO2|A multi-material film system structure is designed, and the specific film system structure is G|0.88(0.5L M 0.5L)^16 0.79(HL)^12 0.67(HL)^11 0.58(HL)^110.49(HL)^11|A, the center wavelength is 550 nanometers (nm), wherein M is a high refractive index material Ta2O5, H is a high refractive index material metal Hf, L is a low refractive index material SiO2, (0.5L M 0.5L)^S is a classic long wave pass film system (Ta2O5-SiO2 film stack), (HL)^S is a classic high reflection film (Hf-SiO2 film stack). Since the transmission region of Ta2O5 is basically 330~10000nm, the characteristics of film materials Ta2O5 and SiO2 are used to make a long wave pass film system greater than 330nm (usually 330nm-1500nm), and then the characteristics of film materials metal Hf and SiO2 are used to make a high reflection film of 250nm~330nm. In this way, the birefringent mirror optical thin film can meet the requirements of high reflectivity and high damage threshold with fewer film layers.

[0129] Then the film system of the original film stack design cannot directly meet the needs of the drawing, so the target is optimized by using software, as shown in Figure 3 and Figure 4 . Figure 3 is the spectral curve of the residual reflectivity of the birefringent mirror under 29° incident angle provided by the application, Figure 4 is the spectral curve of the residual reflectivity of the birefringent mirror under 61° incident angle provided by the application. Figure 3 and Figure 4 , the parameters are the same except that the incident angles are different (the incident angle in Figure 3 is 29°, Figure 4 is 61°). Light source: white light; incident medium: air; substrate refractive index: 1.46; exit refractive index: 1.46; detection: ideal state; center wavelength: 550nm; first surface: front surface; polarization state has three kinds of light, average, S (Senkrecht, vertical polarized light) and P (Parallel, parallel polarized light).

[0130] The design values at 29° can be calculated by software as Ravg=99.3% @ 250-460 nm, 29 deg; Tavg=98.7% @ 1050-1100 nm, 29 deg; Tavg=99.7% @ 1200-1400 nm, 29 deg; the design values at 61° can be calculated by software as Ravg=97.7% @ 250-460 nm, 61 deg; Tavg=96.7% @ 1050-1100 nm, 61 deg; Tavg=96.3% @ 1200-1400 nm, 61 deg; all the above indexes can meet the requirements.

[0131] Process preparation: according to the film system index, a new process of plating method is used in this embodiment: in the Ta2O5-SiO2 combination, the previous substrate film layer needs to be etched for 10-15 minutes by using a Hall ion source, and the vacuum degree before plating is kept below 2*10 -3 Pa, and the deposition temperature is 150-200°C, and the constant temperature is kept for 10-20 minutes; wherein Ta2O5 and SiO2 are respectively assisted by ion source for evaporation to ensure the firmness of the film layer. When plating Ta2O5 film layer, the deposition rate is controlled at 0.2-0.3 nm / s, the oxygen filling amount is 10-20 SCCM, and the film is formed by ion source assisted evaporation. When plating SiO2 film layer, the deposition rate is controlled at 0.5-0.6 nm / s, and the film is formed by ion source assisted evaporation.

[0132] Referring to Table 1, Table 1 is the plating ratio parameter (Tooling) under the process condition.

[0133] Table 1 330-1400 nm waveband film plating ratio parameter

[0134]

[0135] After the above Ta2O5-SiO2 combination plating is completed, a pause plating of 10-20 min is set at the junction of SiO2 and Hf film layer to ensure the firmness of the substrate film layer when Hf is evaporated, and in the Hf-SiO2 combination, when plating each metal Hf film layer, the deposition rate is controlled at 0.06-0.08 nm / s, the oxygen filling amount is 60-80 SCCM, and the film is formed by electron gun evaporation. When plating SiO2 film layer, the deposition rate is controlled at 0.5-0.6 nm / s, and the film is formed by electron gun evaporation. (This stage does not use ion source for assisted evaporation to prevent absorption phenomenon from occurring in the deep ultraviolet waveband and affecting the spectral curve).

[0136] Referring to Table 2, Table 2 is the plating ratio parameter (Tooling) under the process condition.

[0137] Table 2 250~330nm waveband film plating proportion parameter

[0138]

[0139] Table 1 and Table 2 are Tooling obtained under this process, plus the designed film layer thickness (simulated plating thickness), to obtain the actual plating thickness (actual plating thickness) of Table 3 (where is a part of the film layer thickness example).

[0140] Table 3 S1 actual plating film layer thickness part

[0141]

[0142] Due to the large aspect ratio of the dichroic mirror, close to 20, S1 plating will have a greater impact on the surface shape of the original part, so the application innovatively adopts a scheme to minimize the impact of S1 plating on the surface shape. Since the S1 produces a large stress film layer in the ion source Ta2O5 and SiO2 combination, the ion source is used for auxiliary evaporation during the plating of the first layer of S2, and the film thickness is the thickness of SiO2 in the Ta2O5 and SiO2 combination. After the first layer is completed, a pause plating of 10-20 min is set at the SiO2 and Hf film layer junction to ensure the firmness of the substrate film layer during Hf evaporation. In the Ta2O5 and SiO2 combination, the deposition rate is controlled at 0.06-0.08 nm / s, the oxygen flow is 60-80 SCCM, and the film is formed by electron gun evaporation. When plating the SiO2 film layer, the deposition rate is controlled at 0.5-0.6 nm / s, and the film is formed by electron gun evaporation. At the same time, the film system design software is optimized to obtain the design thickness of the S2 antireflection film. According to the Tooling information, the actual thickness (target plating thickness) is obtained as shown in Table 4.

[0143] Table 4 S2 actual plating film layer thickness

[0144]

[0145] Referring to Figures 5 to 7 . Figure 5 is the spectral curve of the residual reflectivity of the dichroic mirror provided by the application under a 29° incident angle, Figure 6 is the spectral curve of the residual reflectivity of the dichroic mirror provided by the application under a 50° incident angle, Figure 7 is the spectral curve of the residual reflectivity of the dichroic mirror provided by the application under a 61° incident angle. Figures 3 to 7 In Table 4, the parameters are different from the incident angle (29°, 50°, and 61°) Figure 5 In Table 4, the incident angle is 29°, Figure 6 In Table 4, the incident angle is 50°, Figure 7The incident angle is 61°, and all other parameters are the same. Light source: white light; incident medium: air; substrate refractive index: 1.46; exit refractive index: 1.46; detection: ideal state; center wavelength: 550nm; first surface: front surface; there are three polarization states: average, S, and P.

[0146] The software can calculate the design values ​​at 29°: Ravg=2.47% @250-650nm, Ravg=1.36%@1050-1100nm, Ravg=1.45%@1200-1400nm, 29deg; Ravg=4.07%@250-650nm, Ravg=2.06%@1050-1100nm, Ravg=3.69%@1200-1400nm, 50deg; Ravg=7.78%@250-650nm, Ravg=5.25%@1050-1100nm, Ravg=7.7%@1200-1400nm, 61deg; all of the above indicators meet the requirements.

[0147] See Figure 8 and Figure 9 , Figure 8 This is a spectral curve of residual reflectance and transmittance of the dichroic mirror provided by the present invention at incident angles of 29-61°. Figure 9 This is a spectral curve of the residual reflectance of the dichroic mirror provided by this invention at incident angles of 29-61°. Actual coating results show that all the above indicators meet the requirements.

[0148] Refer to Tables 5 and 6. Table 5 shows the surface profile data for S1 and S2 surfaces before plating, and Table 6 shows the surface profile data for S1 and S2 surfaces after plating. The data shows that the surface profile (RMS) of the plated product is smaller than that before plating, meeting the required specifications. Furthermore, because the S2 surface uses a "back-pull" method to plate the same thickness of SiO2, the change in the product's surface profile is minimized to achieve a relatively excellent state. This technology also reduces processing costs and polishing pressure during substrate surface profile fabrication.

[0149] Table 5. Surface profile data of S1 and S2 surfaces before plating

[0150]

[0151] Table 6. Surface profile data of S1 and S2 surfaces after plating

[0152]

[0153] The dichroic mirror optical film and the plating method thereof provided by the embodiment of the present application provide a high-reflectivity, high-damage-threshold laser film, three materials are combined, the advantages of different material optical properties and damage characteristics are taken, a Hf-Ta2O5-SiO2 multi-material film system structure is adopted, that is, a Ta2O5-SiO2 film stack is adopted to meet the requirement of high reflectivity, a Hf-SiO2 film stack is superimposed on the outermost part of the film stack, a smaller number of film layers is used to meet the requirement of high reflectivity, and the laser damage resistance of the film is improved, and the film has strong practical value.

[0154] Those skilled in the art can clearly understand from the description of the above embodiments that each embodiment can be realized by means of software and a necessary general hardware platform, and of course, can also be realized by hardware. Based on such understanding, the above technical solutions or the part of the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the method described in each embodiment or some part of the embodiment.

[0155] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A dichroic mirror optical film, characterized in that: the dichroic mirror optical film is composed of a tantalum pentoxide film layer, a silicon dioxide film layer and a metal hafnium film layer plated on a dichroic mirror; the dichroic mirror comprises a first plating surface and a second plating surface; the dichroic mirror optical film comprises a light splitting film plated on the first plating surface and an anti-reflection film plated on the second plating surface; the light splitting film is composed of the tantalum pentoxide film layer, the silicon dioxide film layer and the metal hafnium film layer; and the anti-reflection film is composed of the silicon dioxide film layer and the metal hafnium film layer.

2. The dichroic mirror optical film according to claim 1, characterized in that: the light splitting film is composed of a long-wave pass film system and a high-reflection film; the long-wave pass film system is composed of the tantalum pentoxide film layer and the silicon dioxide film layer; and the high-reflection film is composed of the silicon dioxide film layer and the metal hafnium film layer.

3. The dichroic mirror optical film according to claim 1, characterized in that: the light splitting film comprises at least one layer of the long-wave pass film system and at least one layer of the high-reflection film in order from near to far to the first plating surface; and the anti-reflection film comprises at least one layer of the silicon dioxide film layer and at least one layer of the metal hafnium film layer plated in turn on the second plating surface; and the first film layer plated on the second plating surface is a silicon dioxide film layer.

4. A dichroic mirror, characterized in that: a dichroic mirror optical film composed of a tantalum pentoxide film layer, a silicon dioxide film layer and a metal hafnium film layer is plated on a surface of the dichroic mirror.

5. The dichroic mirror according to claim 4, characterized in that: the dichroic mirror comprises a first plating surface and a second plating surface; the dichroic mirror optical film comprises a light splitting film plated on the first plating surface and an anti-reflection film plated on the second plating surface; the light splitting film is composed of a long-wave pass film system and a high-reflection film; and the dichroic mirror optical film plated on the surface of the dichroic mirror comprises: the long-wave pass film system and the high-reflection film plated in order on the first plating surface; and the anti-reflection film plated on the second plating surface.

6. The dichroic mirror according to claim 5, characterized in that: the long-wave pass film system is composed of the tantalum pentoxide film layer and the silicon dioxide film layer; the high-reflection film is composed of the silicon dioxide film layer and the metal hafnium film layer; the long-wave pass film system and the high-reflection film plated in order on the first plating surface comprises: the tantalum pentoxide film layer in the long-wave pass film system is plated by using an ion source for auxiliary evaporation and controlling a deposition rate to be 0.2-0.3 nanometer per second and an oxygen filling amount to be 10-20 standard cubic centimeters per minute; and the silicon dioxide film layer in the long-wave pass film system is plated by using an ion source for auxiliary evaporation and controlling a deposition rate to be 0.5-0.6 nanometer per second; the high-reflection film is plated after a pause of 10-20 minutes after the long-wave pass film system is plated; the metal hafnium film layer in the high-reflection film is plated by using an electron gun for auxiliary evaporation and controlling a deposition rate to be 0.06-0.08 nanometer per second and an oxygen filling amount to be 60-80 standard cubic centimeters per minute; and the silicon dioxide film layer in the high-reflection film is plated by using an electron gun for auxiliary evaporation and controlling a deposition rate to be 0.5-0.6 nanometer per second.

2. The dichroic mirror optical film of claim 1, wherein ​ ​ ​ 3. The dichroic mirror optical film of claim 2, wherein ​ ​ 4. A plating method for the birefringent mirror optical film of any one of claims 1 to 3, characterized by, ​ The base film layer of the dichroic mirror is etched for 10-15 minutes using a Hall ion source, and the background vacuum is kept below 2*10 -3 Pascals, at a deposition temperature of 150-200 degrees Celsius, for 10-20 minutes. ​ 5. The method of claim 4, wherein the method further comprises: ​ ​ ​ ​ 6. The method of claim 5, wherein the method further comprises: ​ ​ ​ ​ ​ 7. The method of claim 5, wherein the method further comprises: The antireflection film is composed of the silicon dioxide film layer and the hafnium metal film layer; The plating of the antireflection film on the second plating surface comprises: Plating the first silicon dioxide film layer of the antireflection film on the second plating surface; After the plating of the first silicon dioxide film layer is completed, the plating of the hafnium metal film layer and other silicon dioxide film layers of the antireflection film is suspended for 10-20 minutes and then resumed, the other silicon dioxide film layers being any silicon dioxide film layer of the antireflection film except the first silicon dioxide film layer; When plating the hafnium metal film layer of the antireflection film, electron gun is used for auxiliary evaporation, and the deposition rate is controlled to be 0.06-0.08 nm / s, and the oxygen filling amount is controlled to be 60-80 standard cubic centimeters per minute; When plating the silicon dioxide film layer of the antireflection film, the deposition rate is controlled to be 0.5-0.6 nm / s, and ion source is used for auxiliary evaporation of the first silicon dioxide film layer, and electron gun is used for auxiliary evaporation of the other silicon dioxide film layers.

8. The method of claim 5, wherein the method further comprises: Before the long-wave pass film system and the high-reflection film are plated on the first plating surface in sequence, the method further comprises: Obtaining a plating proportion parameter and a plating target corresponding to the dichroic mirror; According to the plating target and the plating proportion parameter, target plating thicknesses of each tantalum pentoxide film layer, target plating thicknesses of each silicon dioxide film layer and target plating thicknesses of each hafnium metal film layer in the split film are determined respectively; According to the target plating thicknesses of each silicon dioxide film layer in the long-wave pass film system, the plating target and the plating proportion parameter, target plating thicknesses of each silicon dioxide film layer and target plating thicknesses of each hafnium metal film layer in the antireflection film are determined respectively.

9. The method of claim 8, wherein the method further comprises: According to the target plating thicknesses of each silicon dioxide film layer in the long-wave pass film system, the plating target and the plating proportion parameter, target plating thicknesses of each silicon dioxide film layer and target plating thicknesses of each hafnium metal film layer in the antireflection film are determined respectively, comprising: The sum of the target plating thicknesses of each silicon dioxide film layer in the long-wave pass film system is calculated to obtain the target plating thickness of the first silicon dioxide film layer in the antireflection film; According to the target plating thickness of the first silicon dioxide film layer, the plating target and the plating proportion parameter, target plating thicknesses of each other silicon dioxide film layer and target plating thicknesses of each hafnium metal film layer in the antireflection film are determined respectively, the other silicon dioxide film layers being any silicon dioxide film layer of the antireflection film except the first silicon dioxide film layer.

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