Multilayer optical film, preparation method thereof and imaging device

Abstract

The invention discloses a multilayer optical film, a preparation method thereof and an imaging device. The preparation method comprises the following steps: providing an optical glass substrate, depositing an anti-reflection layer on the optical glass substrate, carrying out pattern design on the anti-reflection layer by using a beam splitting film design algorithm, and transferring a designed beam splitting pattern to the anti-reflection layer; depositing a high-damage-threshold protection layer on the anti-reflection layer, depositing a thermal management layer on the high-damage-threshold protection layer, depositing a reflection layer on the thermal management layer in an evaporation mode, forming a multi-layer film structure, carrying out annealing treatment on the formed multi-layer film structure, and setting the annealing condition as a preset temperature so as to improve the interface bonding force between the multi-layer film structure. Obtaining a multi-layer optical film; through the optimal design of the whole preparation process, the laser damage resistance is considered, the heat management layer provides heat stability, and the reflecting layer improves the efficiency of an optical system, so that the multi-layer optical film with high performance and multiple functions is manufactured, and the multi-layer optical film is suitable for high requirements of a laser display system.

Description

Technical Field

[0001] The present invention relates to the field of optical display technology, and in particular to a multilayer optical film and a preparation method thereof, and an imaging device. Background Art

[0002] With the rapid development of laser display technology, laser imaging display systems have shown great potential in high-brightness display and high-definition applications. Laser display technology has been widely used in various display screens, including televisions, projectors, computer monitors and other devices due to its bright colors, high brightness and superior resolution. However, in laser display systems, the performance of optical films is crucial to the overall performance of the system. Especially under high-power laser irradiation, how to ensure the stability of the optical film layer, improve light transmittance, reduce heat loss and prevent laser damage has become a technical challenge that the industry needs to solve urgently.

[0003] At present, most of the optical thin film products available on the market use traditional anti-reflective film and protective film structures. These film layers are usually prepared by physical vapor deposition (PVD) or chemical vapor deposition (CVD) technology. For example, traditional anti-reflective films usually use magnesium fluoride or silicon dioxide materials to reduce the reflection loss of light and increase the transmittance. However, the anti-reflective film layers of the prior art often lack sufficient resistance to laser damage when facing high-power lasers, which will cause damage to the film layer during use, seriously affecting the long-term stability of the display system. Although some technologies improve the damage resistance of the film layer by adding a protective film, these film layers usually sacrifice transmittance and thermal stability, making it difficult to achieve the best balance in the laser display system. In summary, the optical film products of the prior art generally have the disadvantages of poor resistance to laser damage, insufficient thermal stability, and low optical efficiency.

[0004] In view of this, it is necessary to improve the optical film product technology in the prior art to solve Summary of the invention The purpose of the present invention is to provide a multilayer optical film and a preparation method thereof, and an imaging device to solve the above technical problems.

[0005] To achieve this object, the present invention adopts the following technical solutions: A method for preparing a multilayer optical film, comprising: Step S1, providing an optical glass substrate, and depositing an anti-reflection layer on the optical glass substrate by reactive magnetron sputtering technology, wherein the anti-reflection layer adopts magnesium fluoride or silicon dioxide material to form an anti-reflection layer with high transparency; Step S2, using a spectroscopic film design algorithm to design a pattern for the anti-reflection layer, and transferring the designed spectroscopic pattern to the anti-reflection layer; Step S3, depositing a high damage threshold protection layer on the anti-reflection layer, wherein the high damage threshold protection layer is made of silicon nitride or aluminum nitride; Step S4, depositing a thermal management layer on the high damage threshold protection layer, wherein the thermal management layer is made of metal oxide or nitride with high thermal conductivity to improve the thermal stability of the film; Step S5, depositing a reflective layer on the thermal management layer by evaporation to form a multilayer film structure, wherein the reflective layer is made of metal material such as aluminum or silver to provide total reflection; Step S6, annealing the formed multilayer film structure, setting the annealing condition to a preset temperature to improve the interface bonding strength between the multilayer film structures, and obtaining a multilayer optical film.

[0006] Optionally, the preparation process of the optical glass substrate is specifically as follows: Step S101, determining the required optical glass composition according to the design requirements and selecting the raw materials suitable for manufacturing the optical glass; Step S102, mixing the selected raw materials in a preset ratio and melting them into glass liquid under high temperature conditions, usually at a melting temperature of 1500° C. to 2000° C.; Step S103, forming the molten glass into an optical glass substrate with a preset shape through a mold; Step S104, performing surface treatment on the optical glass substrate by chemical polishing, and then cleaning the substrate surface by ultrasonic cleaning to remove surface contaminants.

[0007] Optionally, the step S1 specifically includes: Step S11, fixing a clean transparent glass substrate into a deposition chamber and performing a preliminary inspection on the reactive magnetron sputtering equipment; Step S12, placing the cleaned optical glass substrate in a reactive magnetron sputtering device, and starting surface pretreatment, specifically, using low-energy argon plasma to treat the substrate surface to remove residual contaminants on the surface and activate the substrate surface. The power during the treatment process is 100 W, the argon flow rate is set to 20 sccm, and the treatment time is 3 minutes; Step S13, in the reactive magnetron sputtering process, magnesium fluoride or silicon dioxide is selected as the anti-reflection layer material, oxygen is used as the reaction gas, and the thickness of the film is controlled by adjusting the sputtering power, gas flow rate and working pressure to perform reactive magnetron sputtering deposition; Step S14, during the reactive magnetron sputtering process, adjusting the distance between the magnesium fluoride or silicon dioxide material target and the optical glass substrate to optimize the deposition uniformity of the thin film; Step S15, after the deposition process is completed, the film thickness is measured in real time using an optical film thickness meter, and the film transmittance is tested using an ultraviolet visible spectrophotometer to ensure that the film transmittance reaches more than 90%.

[0008] Optionally, the step S2 specifically includes: Step S21, using optical design software to model the optical performance of the anti-reflection layer, ensuring that the designed spectroscopic pattern can effectively improve the transmittance of light and reduce reflection through the spectroscopic film design algorithm, and selecting the corresponding material refractive index and film thickness to meet the preset wavelength range requirements; Step S22, in the process of designing the spectroscopic pattern, by adjusting the thickness distribution, number of layers and optical path difference of the film layer, the designed anti-reflection pattern can generate multiple interferences within the required spectral range, thereby achieving a wide-band or narrow-band anti-reflection effect; S23, after the design of the spectroscopic pattern is completed, a digital pattern file is generated and converted into a photolithography template, and the designed spectroscopic pattern is transferred to the anti-reflection layer on the optical glass substrate using a patterned exposure technology; S24, using a scanning electron microscope to check the pattern structure after the pattern transfer, to detect whether there is distortion or error in the pattern structure, and to make corrections by adjusting the exposure intensity or exposure time according to the deviation result; S25, after the pattern transfer is completed, reactive ion etching technology is used, and etching gas is selected for dry etching to remove unnecessary film layers and retain the designed spectroscopic pattern. The power during the etching process is set to 150W, the gas flow rate is 15sccm, and the working pressure is controlled at 1Pa.

[0009] Optionally, the step S3 specifically includes: Step S31, using a mixture of deionized water and isopropyl alcohol to perform ultrasonic cleaning, the cleaning process lasts for 5 minutes to remove impurities remaining on the surface of the optical substrate to perform surface cleaning treatment; Step S32, transferring the cleaned optical substrate to a reactive magnetron sputtering device for a deposition process, and operating according to the set initial sputtering parameters; Step S33, during the deposition process, dynamically adjusting the gas flow rate and power parameters according to the reactivity and deposition rate of the film to optimize the physical and optical properties of the film layer; Step S34, after the deposition is completed, a transmittance test is performed on the deposited high damage threshold protective layer using an ultraviolet visible spectrophotometer to ensure that the film layer has good light transmittance within the required wavelength band.

[0010] Optionally, the step S4 specifically includes: Step S41, transferring the optical substrate to a metal oxide or nitride deposition device with high thermal conductivity, preparing for deposition of the thermal management layer, the initial deposition adjustment settings are to control the sputtering power to 350W, the oxygen flow rate to 15sccm, and the working pressure to 0.3Pa; S42, during the deposition process, the film thickness is monitored in real time, an optical film thickness meter is used to track the growth rate of the film layer, and the deposition rate is adjusted to control the thickness of the thermal management layer to be between 50 and 150 nanometers; S43, during the process of depositing the thermal management layer, controlling the nitrogen flow rate to 10 sccm and the oxygen flow rate to 5 sccm to adjust the composition of the film layer; S44, after the deposition is completed, the transmittance of the thermal management layer is tested using a UV-visible spectrophotometer to ensure that the transmittance of the film layer reaches at least 90%; S45, perform film quality inspection, use an optical film thickness meter to check the thickness uniformity of the film layer, and use an electron microscope to check the surface quality of the film layer to determine whether the deposition quality of the thermal management layer meets the design requirements.

[0011] Optionally, the step S5 specifically includes: Step S51, using a mixed solution of deionized water and isopropyl alcohol to clean the surface of the thermal management layer for 5 minutes. After the cleaning is completed, the substrate is blown dry with nitrogen to ensure that there is no moisture remaining on the surface; Step S52, transfer the cleaned optical substrate to the vacuum evaporation equipment and set the initial evaporation process parameters. During the deposition process, use aluminum or silver target material, evaporate through a resistance heating source, control the evaporation power to 120W, and set the system working pressure to 2×10⁻ 6 Torr; Step S53, during the deposition of the reflective layer, the deposition rate is set to 1.5 nm per minute, and the final thickness of the film layer is controlled between 100 nm and 200 nm; a directional evaporation source is used, the distance between the evaporation source and the substrate is adjusted, the evaporation angle and flow direction are controlled, and the uniformity of the film layer is ensured.

[0012] Optionally, after step S53, the following steps are further included: Step S54, after the deposition is completed, the reflectivity of the reflective layer is tested using an ultraviolet visible spectrophotometer to determine whether the reflective layer can provide a near-total reflection effect within the required wavelength band, and the optical performance of the reflective layer is evaluated by transmittance and reflectivity tests; Step S55, using standard reflection test equipment to comprehensively measure the reflectivity of the reflection layer, determine whether the reflectivity reaches the expected design value, and perform a full-spectrum reflectivity test.

[0013] The present invention also provides a multilayer optical film, which is prepared by the method for preparing the multilayer optical film as described above, and the multilayer optical film specifically comprises: Optical glass substrate; An anti-reflection layer having an anti-reflection effect is deposited on the optical glass substrate; A high damage threshold protection layer deposited on the anti-reflection layer is made of silicon nitride or aluminum nitride; A thermal management layer deposited on the high damage threshold protection layer is made of metal oxide or nitride material; The reflective layer deposited on the heat management layer is made of aluminum or silver metal material to provide total reflection.

[0014] The present invention also provides an imaging device, comprising the multilayer optical film as described above.

[0015] Compared with the prior art, the present invention has the following beneficial effects: first, an optical glass substrate is provided, and an anti-reflection layer is deposited by reactive magnetron sputtering technology to make it have high transparency, a spectroscopic film design algorithm is used to design a pattern for the anti-reflection layer and transfer it to the film layer, the optical performance is optimized by forming a multi-layer film structure, and then a high damage threshold protection layer is deposited to improve the film layer's ability to resist laser damage, and then a thermal management layer is deposited to improve the thermal stability of the film layer, and then a reflective layer is deposited by evaporation to form a multi-layer film structure to provide total reflection and enhance the laser display effect; after all the layers are completed, an annealing treatment is performed to enhance the bonding strength between the thin film layers, thereby improving the overall performance and stability of the film layer; the method optimizes the design of the overall preparation process and takes into account the ability to resist laser damage, the thermal management layer provides thermal stability, and the reflective layer improves the efficiency of the optical system, thereby producing a high-performance, multifunctional multi-layer optical film that meets the high requirements of the laser display system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0018] Figure 1 This is one of the schematic flow diagrams of the method for preparing the multilayer optical film of the first embodiment; Figure 2 The second schematic diagram is a process flow diagram of the method for preparing the multilayer optical film of the first embodiment; Figure 3 This is the third flow chart of the method for preparing the multilayer optical film of the first embodiment. DETAILED DESCRIPTION

[0019] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0021] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0022] Embodiment 1: Combination Figures 1 to 3 As shown, an embodiment of the present invention provides a method for preparing a multilayer optical film, comprising: Step S1, providing an optical glass substrate, and depositing an anti-reflection layer on the optical glass substrate by reactive magnetron sputtering technology, wherein the anti-reflection layer adopts magnesium fluoride or silicon dioxide material, wherein preferably, rare earth elements can be added to optimize the optical performance to form an anti-reflection layer with high transparency.

[0023] Step S2, use the spectroscopic film design algorithm to design the pattern of the anti-reflection layer, and transfer the designed spectroscopic pattern to the anti-reflection layer; adjust the wavelength selectivity through the multi-layer structure of the interference film. The designed spectroscopic pattern optimizes light transmittance, reduces reflection, and the design meets the requirements of ultra-short focus characteristics to achieve efficient optical performance.

[0024] Step S3, depositing a high damage threshold protection layer on the anti-reflection layer, the high damage threshold protection layer adopts silicon nitride or aluminum nitride material; to improve the damage resistance and thermal stability of the film layer, and ensure the long-term stability of the film under strong light environment.

[0025] Step S4, depositing a thermal management layer on the high damage threshold protection layer. The thermal management layer uses metal oxides or nitrides with high thermal conductivity to improve the thermal stability of the film; improve the thermal stability and light resistance of the film, reduce the interference of ambient light on the display effect, and improve color saturation.

[0026] Step S5, depositing a reflective layer on the heat management layer by evaporation to form a multi-layer film structure. The reflective layer is made of metal materials such as aluminum or silver to provide total reflection and help guide or recover the laser beam.

[0027] Step S6, annealing the formed multilayer film structure, setting the annealing condition to a preset temperature to improve the interface bonding strength between the multilayer film structures, and obtaining a multilayer optical film.

[0028] The working principle of the present invention is as follows: first, an optical glass substrate is provided, and an anti-reflection layer is deposited by reactive magnetron sputtering technology to make it have high transparency, a spectroscopic film design algorithm is used to design a pattern for the anti-reflection layer and transfer it to the film layer, and the optical performance is optimized by forming a multi-layer film structure, and then a high damage threshold protection layer is deposited to improve the film layer's ability to resist laser damage, and then a thermal management layer is deposited to improve the film layer's thermal stability, and then a reflective layer is deposited by evaporation to form a multi-layer film structure to provide total reflection and enhance the laser display effect; after all levels are completed, annealing treatment is performed to enhance the bonding strength between the thin film layers, thereby improving the overall performance and stability of the film layer; this method optimizes the design of the overall preparation process and takes into account the ability to resist laser damage, the thermal management layer provides thermal stability, and the reflective layer improves the efficiency of the optical system, thereby producing a high-performance, multifunctional multi-layer optical film that meets the high requirements of the laser display system.

[0029] In this embodiment, it is specifically described that the preparation process of the optical glass substrate is as follows: Step S101, determining the required optical glass composition according to the design requirements, and selecting raw materials suitable for manufacturing the optical glass.

[0030] Step S102, mixing the selected raw materials in a preset ratio and melting them into glass liquid under high temperature conditions, usually at a melting temperature of 1500°C to 2000°C.

[0031] Step S103, forming the molten glass into an optical glass substrate having a preset shape through a mold; the forming method can be selected according to needs, such as float process, wire drawing process or calendering process.

[0032] Step S104, performing surface treatment on the optical glass substrate by chemical polishing, and then cleaning the substrate surface by ultrasonic cleaning to remove surface contaminants.

[0033] Process: Deionized water, acetone or ethanol are often used for cleaning, followed by drying in a nitrogen stream.

[0034] In this embodiment, it is specifically explained that step S1 specifically includes: Step S11, fixing the clean transparent glass substrate into the deposition chamber, and performing a preliminary inspection on the reactive magnetron sputtering equipment.

[0035] Step S12, placing the cleaned optical glass substrate in a reactive magnetron sputtering device and starting surface pretreatment, specifically using low-energy argon plasma to treat the substrate surface to remove residual contaminants on the surface and activate the substrate surface. The power during the treatment process is 100 W, the argon flow rate is set to 20 sccm, and the treatment time is 3 minutes.

[0036] Step S13, during the reactive magnetron sputtering process, magnesium fluoride or silicon dioxide is selected as the anti-reflection layer material, oxygen is used as the reaction gas, the thickness of the film is controlled by adjusting the sputtering power, gas flow rate and working pressure, and reactive magnetron sputtering deposition is performed; the sputtering power is set to 200 W, the oxygen flow rate is 5 sccm, and the working pressure is maintained at a low pressure state of 0.3 Pa.

[0037] Step S14, during the reactive magnetron sputtering process, the distance between the magnesium fluoride or silicon dioxide material target and the optical glass substrate is adjusted to optimize the deposition uniformity of the film; the distance is controlled within 50 mm to ensure good coverage and optical performance of the film layer. The deposition rate is controlled at 1.5 nm per minute to ensure that the thickness of the anti-reflection layer is uniform and has high transparency.

[0038] Step S15, after the deposition process is completed, the film thickness is measured in real time using an optical film thickness meter, and the film transmittance is tested using an ultraviolet visible spectrophotometer to ensure that the film transmittance reaches more than 90%.

[0039] Ensure that the thickness of the anti-reflection layer is precisely controlled between 30 and 50 nm. This thickness range can effectively reduce the reflection of light and ensure the anti-reflection effect with high transparency.

[0040] Finally, the deposited anti-reflection layer was heat treated to eliminate the internal stress that may occur during the thin film deposition process and further improve the transparency and stability of the film layer. The heat treatment temperature was set to 150°C and the treatment time was 30 minutes.

[0041] In this embodiment, it is specifically described that step S2 specifically includes: Step S21, use optical design software (such as TFCalc or FilmStar) to model the optical performance of the anti-reflection layer, ensure that the designed spectroscopic pattern can effectively improve the transmittance of light and reduce reflection through the spectroscopic film design algorithm, and select the corresponding material refractive index and film thickness to meet the preset wavelength range requirements.

[0042] Step S22, during the design of the spectroscopic pattern, by adjusting the thickness distribution, number of layers and optical path difference of the film layer, the designed anti-reflection pattern can produce multiple interferences within the required spectral range, thereby achieving a wide-band or narrow-band anti-reflection effect; specifically, the design wavelength range can be set to between 400 nm and 700 nm to meet the requirements of the visible spectrum.

[0043] S23, after the design of the spectroscopic pattern is completed, a digital pattern file is generated and converted into a photolithography template, and a patterned exposure technology (such as electron beam exposure or laser exposure) is used to transfer the designed spectroscopic pattern to the anti-reflection layer on the optical glass substrate; through this step, high-precision transfer of the pattern can be ensured, and the stability of the optical performance can be ensured.

[0044] S24, using a scanning electron microscope to check the pattern structure after the pattern transfer, to detect whether there is distortion or error in the pattern structure, and to make corrections by adjusting the exposure intensity or exposure time according to the deviation result.

[0045] S25, after the pattern transfer is completed, reactive ion etching technology is used, and etching gas is selected for dry etching to remove unnecessary film layers and retain the designed spectroscopic pattern. The power during the etching process is set to 150W, the gas flow rate is 15sccm, and the working pressure is controlled at 1Pa.

[0046] After etching, a cleaning step is performed, using a combination of deionized water and ultrasonic cleaning to completely remove the etching residues remaining on the substrate. Subsequently, nitrogen is used to blow dry to ensure that the pattern is clear and free of dirt, and does not affect the deposition of subsequent film layers.

[0047] In this embodiment, it is specifically described that step S3 specifically includes: Step S31, using a mixture of deionized water and isopropyl alcohol to perform ultrasonic cleaning, the cleaning process lasts for 5 minutes to remove impurities remaining on the surface of the optical substrate, so as to perform surface cleaning treatment.

[0048] Step S32, the cleaned optical substrate is transferred to a reactive magnetron sputtering device for deposition, and the deposition is performed according to the set initial sputtering parameters; specifically, silicon nitride or aluminum nitride is selected as the target material, and nitrogen is added as the reaction gas during the deposition process. The sputtering power is set to 300W, the nitrogen flow rate is 10sccm, and the working pressure is maintained at 0.4Pa to ensure that the deposited film has high density and uniformity.

[0049] During the deposition process, the deposition rate of silicon nitride or aluminum nitride is controlled to ensure uniform thickness of the film. The deposition rate is set to 2 nm per minute to ensure that the film has sufficient thickness and a high damage threshold. According to the design requirements, the final thickness of the film is controlled to be between 50 nm and 100 nm to ensure its protective effect in high-energy environments such as laser radiation.

[0050] Step S33, during the deposition process, the gas flow rate and power parameters are dynamically adjusted according to the reactivity and deposition rate of the film to optimize the physical and optical properties of the film layer; during this process, a real-time monitoring system (such as an optical film thickness meter) is used to monitor the deposition thickness of the film layer to ensure that the film layer is within a specified range.

[0051] Step S34, after the deposition is completed, the transmittance of the deposited high damage threshold protective layer is tested using a UV-visible spectrophotometer to ensure that the film layer has good light transmittance in the required band and has a high damage threshold. In addition, a scanning electron microscope (SEM) is used to inspect the surface of the film layer to ensure the uniformity and density of the film layer, and to ensure that it can effectively protect the lower anti-reflection layer from the influence of the external environment.

[0052] In this embodiment, it is specifically described that step S4 specifically includes: Step S41, transfer the optical substrate to a metal oxide or nitride deposition device with high thermal conductivity, and prepare for the deposition of the thermal management layer. The initial adjustment settings of the deposition are to control the sputtering power to 350 W, the oxygen flow rate to 15 sccm, and the working pressure to 0.3 Pa; select aluminum, copper, aluminum oxide or aluminum nitride as the deposition material of the thermal management layer to ensure that the film layer has good thermal conductivity.

[0053] S42, during the deposition process, the film thickness is monitored in real time, an optical film thickness meter is used to track the growth rate of the film layer, and the deposition rate is adjusted to control the thickness of the thermal management layer to be between 50 and 150 nanometers; Depending on the characteristics of the material, the deposition rate is set at 2 to 3 nanometers per minute to ensure the uniformity of the film layer so that the thermal management layer evenly covers the surface of the high damage threshold protection layer.

[0054] S43, during the process of depositing the thermal management layer, controlling the nitrogen flow rate to 10 sccm and the oxygen flow rate to 5 sccm to adjust the composition of the film layer; In order to optimize the thermal management performance, the ratio of nitrogen and oxygen is controlled to ensure that the deposited thermal management layer has good thermal conductivity and the necessary chemical stability. Through this adjustment, the thermal conductivity of the film layer reaches more than 100W / m·K, which can effectively disperse and conduct heat.

[0055] S44, after the deposition is completed, the transmittance of the thermal management layer is tested using a UV-visible spectrophotometer to ensure that the transmittance of the film layer reaches at least 90% to reduce the impact on the optical properties of the underlying film. At the same time, the surface structure of the film layer is observed by a scanning electron microscope (SEM) to confirm that the film layer has no defects such as cracks, peeling or particles.

[0056] S45, perform film quality inspection, use an optical film thickness meter to check the thickness uniformity of the film layer, and use an electron microscope to check the surface quality of the film layer to determine whether the deposition quality of the thermal management layer meets the design requirements.

[0057] In this embodiment, it is specifically described that step S5 specifically includes: Step S51, using a mixed solution of deionized water and isopropyl alcohol to clean the surface of the thermal management layer for 5 minutes. After the cleaning is completed, the substrate is blown dry with nitrogen to ensure that there is no moisture remaining on the surface; To remove impurities that may affect the deposition of thin films, a mixed solution of deionized water and isopropyl alcohol was used for cleaning, and an ultrasonic cleaner was used for 5 minutes. After cleaning, the substrate was dried with nitrogen to ensure that there was no residual moisture on the surface to ensure the quality of the deposition of the reflective layer.

[0058] Step S52, transfer the cleaned optical substrate to the vacuum evaporation equipment and set the initial evaporation process parameters. During the deposition process, use aluminum or silver target material, evaporate through a resistance heating source, control the evaporation power to 120W, and set the system working pressure to 2×10⁻ 6 Torr; The selected reflective layer material is aluminum or silver, which has good reflective properties and optical stability to ensure high vacuum conditions in the evaporation process, which is conducive to uniform deposition and high density of the film layer.

[0059] Step S53, during the deposition of the reflective layer, the deposition rate is set to 1.5 nm per minute, and the final thickness of the film layer is controlled between 100 nm and 200 nm; a directional evaporation source is used, the distance between the evaporation source and the substrate is adjusted, and the evaporation angle and flow direction are controlled to ensure the uniformity of the film layer; Maintaining an appropriate deposition rate to ensure uniformity and reflective effect of the film layer, the thickness range of 100 nm to 200 nm ensures that the reflective layer has excellent reflective ability and will not adversely affect the underlying optical film.

[0060] During the deposition process, the evaporation rate of aluminum or silver needs to be precisely controlled to ensure uniform coverage of the reflective layer over the entire substrate surface and to avoid inconsistent film thickness.

[0061] Step S54, after the deposition is completed, use a UV-visible spectrophotometer to test the reflectivity of the reflective layer to determine whether the reflective layer can provide a near-total reflection effect within the required band, and evaluate the optical performance of the reflective layer through transmittance and reflectivity tests; ensure that its reflectivity reaches more than 90% and the optical stability of the reflective layer is good.

[0062] Step S55, use standard reflection test equipment to comprehensively measure the reflectivity of the reflection layer, determine whether the reflectivity reaches the expected design value, and perform full spectrum reflectivity test to ensure that the reflection layer has good reflection performance in the required band. In this process, the film layer exhibits uniform reflection performance in the entire spectrum range.

[0063] Embodiment 2: The present invention further provides a multilayer optical film, which is prepared by the method for preparing the multilayer optical film of Example 1. The multilayer optical film specifically comprises: Optical glass substrate; An anti-reflection layer having an anti-reflection effect is deposited on an optical glass substrate; A high damage threshold protection layer deposited on the anti-reflection layer, using silicon nitride or aluminum nitride material; A thermal management layer deposited on the high damage threshold protection layer, using metal oxide or nitride materials; The reflective layer deposited on the heat management layer is made of aluminum or silver metal material to provide total reflection.

[0064] Embodiment three: The present invention also provides an imaging device, comprising the multilayer optical film of the second embodiment.

[0065] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a multilayer optical film, characterized in that: include: Step S1, providing an optical glass substrate, and depositing an anti-reflection layer on the optical glass substrate by reactive magnetron sputtering technology, wherein the anti-reflection layer adopts magnesium fluoride or silicon dioxide material to form an anti-reflection layer with high transparency; Step S2, using a spectroscopic film design algorithm to design a pattern for the anti-reflection layer, and transferring the designed spectroscopic pattern to the anti-reflection layer; Step S3, depositing a high damage threshold protection layer on the anti-reflection layer, wherein the high damage threshold protection layer is made of silicon nitride or aluminum nitride; Step S4, depositing a thermal management layer on the high damage threshold protection layer, wherein the thermal management layer is made of metal oxide or nitride with high thermal conductivity to improve the thermal stability of the film; Step S5, depositing a reflective layer on the thermal management layer by evaporation to form a multilayer film structure, wherein the reflective layer is made of metal material such as aluminum or silver to provide total reflection; Step S6, annealing the formed multilayer film structure, setting the annealing condition to a preset temperature to improve the interface bonding strength between the multilayer film structures, and obtaining a multilayer optical film.

2. The method for preparing a multilayer optical film according to claim 1, characterized in that: The preparation process of the optical glass substrate is specifically as follows: Step S101, determining the required optical glass composition according to the design requirements and selecting the raw materials suitable for manufacturing the optical glass; Step S102, mixing the selected raw materials in a preset ratio and melting them into glass liquid under high temperature conditions, usually at a melting temperature of 1500° C. to 2000° C.; Step S103, forming the molten glass into an optical glass substrate with a preset shape through a mold; Step S104, performing surface treatment on the optical glass substrate by chemical polishing, and then cleaning the substrate surface by ultrasonic cleaning to remove surface contaminants.

3. The method for preparing a multilayer optical film according to claim 2, characterized in that: The step S1 specifically includes: Step S11, fixing a clean transparent glass substrate into a deposition chamber and performing a preliminary inspection on the reactive magnetron sputtering equipment; Step S12, placing the cleaned optical glass substrate in a reactive magnetron sputtering device, and starting surface pretreatment, specifically, using low-energy argon plasma to treat the substrate surface to remove residual contaminants on the surface and activate the substrate surface. The power during the treatment process is 100 W, the argon flow rate is set to 20 sccm, and the treatment time is 3 minutes; Step S13, in the reactive magnetron sputtering process, magnesium fluoride or silicon dioxide is selected as the anti-reflection layer material, oxygen is used as the reaction gas, and the thickness of the film is controlled by adjusting the sputtering power, gas flow rate and working pressure to perform reactive magnetron sputtering deposition; Step S14, during the reactive magnetron sputtering process, adjusting the distance between the magnesium fluoride or silicon dioxide material target and the optical glass substrate to optimize the deposition uniformity of the thin film; Step S15, after the deposition process is completed, the film thickness is measured in real time using an optical film thickness meter, and the film transmittance is tested using an ultraviolet visible spectrophotometer to ensure that the film transmittance reaches more than 90%.

4. The method for preparing a multilayer optical film according to claim 3, characterized in that: The step S2 specifically includes: Step S21, using optical design software to model the optical performance of the anti-reflection layer, ensuring that the designed spectroscopic pattern can effectively improve the transmittance of light and reduce reflection through the spectroscopic film design algorithm, and selecting the corresponding material refractive index and film thickness to meet the preset wavelength range requirements; Step S22, in the process of designing the spectroscopic pattern, by adjusting the thickness distribution, number of layers and optical path difference of the film layer, the designed anti-reflection pattern can generate multiple interferences within the required spectral range, thereby achieving a wide-band or narrow-band anti-reflection effect; S23, after the design of the spectroscopic pattern is completed, a digital pattern file is generated and converted into a photolithography template, and the designed spectroscopic pattern is transferred to the anti-reflection layer on the optical glass substrate using a patterned exposure technology; S24, using a scanning electron microscope to check the pattern structure after the pattern transfer, to detect whether there is distortion or error in the pattern structure, and to make corrections by adjusting the exposure intensity or exposure time according to the deviation result; S25, after the pattern transfer is completed, reactive ion etching technology is used, and etching gas is selected for dry etching to remove unnecessary film layers and retain the designed spectroscopic pattern. The power during the etching process is set to 150W, the gas flow rate is 15sccm, and the working pressure is controlled at 1Pa.

5. The method for preparing a multilayer optical film according to claim 1, characterized in that: The step S3 specifically includes: Step S31, using a mixture of deionized water and isopropyl alcohol to perform ultrasonic cleaning, the cleaning process lasts for 5 minutes to remove impurities remaining on the surface of the optical substrate to perform surface cleaning treatment; Step S32, transferring the cleaned optical substrate to a reactive magnetron sputtering device for a deposition process, and operating according to the set initial sputtering parameters; Step S33, during the deposition process, dynamically adjusting the gas flow rate and power parameters according to the reactivity and deposition rate of the film to optimize the physical and optical properties of the film layer; Step S34, after the deposition is completed, a transmittance test is performed on the deposited high damage threshold protective layer using an ultraviolet visible spectrophotometer to ensure that the film layer has good light transmittance within the required wavelength band.

6. The method for preparing a multilayer optical film according to claim 1, characterized in that: The step S4 specifically includes: Step S41, transferring the optical substrate to a metal oxide or nitride deposition device with high thermal conductivity, preparing for deposition of the thermal management layer, the initial deposition adjustment settings are to control the sputtering power to 350W, the oxygen flow rate to 15sccm, and the working pressure to 0.3Pa; S42, during the deposition process, the film thickness is monitored in real time, an optical film thickness meter is used to track the growth rate of the film layer, and the deposition rate is adjusted to control the thickness of the thermal management layer to be between 50 and 150 nanometers; S43, during the process of depositing the thermal management layer, controlling the nitrogen flow rate to 10 sccm and the oxygen flow rate to 5 sccm to adjust the composition of the film layer; S44, after the deposition is completed, the transmittance of the thermal management layer is tested using a UV-visible spectrophotometer to ensure that the transmittance of the film layer reaches at least 90%; S45, perform film quality inspection, use an optical film thickness meter to check the thickness uniformity of the film layer, and use an electron microscope to check the surface quality of the film layer to determine whether the deposition quality of the thermal management layer meets the design requirements.

7. The method for preparing a multilayer optical film according to claim 1, characterized in that: The step S5 specifically includes: Step S51, using a mixed solution of deionized water and isopropyl alcohol to clean the surface of the thermal management layer for 5 minutes. After the cleaning is completed, the substrate is blown dry with nitrogen to ensure that there is no moisture remaining on the surface; Step S52, transfer the cleaned optical substrate to the vacuum evaporation equipment and set the initial evaporation process parameters. During the deposition process, use aluminum or silver target material, evaporate through a resistance heating source, control the evaporation power to 120W, and set the system working pressure to 2×10⁻ 6 Torr; Step S53, during the deposition of the reflective layer, the deposition rate is set to 1.5 nm per minute, and the final thickness of the film layer is controlled between 100 nm and 200 nm; a directional evaporation source is used, the distance between the evaporation source and the substrate is adjusted, the evaporation angle and flow direction are controlled, and the uniformity of the film layer is ensured.

8. The method for preparing a multilayer optical film according to claim 7, characterized in that: After step S53, the following steps are further included: Step S54, after the deposition is completed, the reflectivity of the reflective layer is tested using an ultraviolet visible spectrophotometer to determine whether the reflective layer can provide a near-total reflection effect within the required wavelength band, and the optical performance of the reflective layer is evaluated by transmittance and reflectivity tests; Step S55, using standard reflection test equipment to comprehensively measure the reflectivity of the reflection layer, determine whether the reflectivity reaches the expected design value, and perform a full-spectrum reflectivity test.

9. A multilayer optical film, characterized in that: The multilayer optical film is prepared by the method for preparing the multilayer optical film according to any one of claims 1 to 8, wherein the multilayer optical film specifically comprises: Optical glass substrate; An anti-reflection layer having an anti-reflection effect is deposited on the optical glass substrate; A high damage threshold protection layer deposited on the anti-reflection layer is made of silicon nitride or aluminum nitride; A thermal management layer deposited on the high damage threshold protection layer is made of metal oxide or nitride material; The reflective layer deposited on the heat management layer is made of aluminum or silver metal material to provide total reflection.

10. An imaging device, characterized in that: Comprising the multilayer optical film of claim 9.

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