Optical thin film and preparation method and application thereof

Abstract

The invention relates to an optical thin film and a preparation method and application thereof. The optical thin film comprises a substrate, a dielectric thin film and a nano-structure surface layer which are sequentially stacked, the material of the nano-structure surface layer is selected from fluorine-containing resin or nano organic silicon, and the porosity of the nano-structure surface layer is 20%-91%; wherein the surface, far away from the substrate, of the nano-structure surface layer is provided with a concave-convex structure, the maximum width of the bottom, close to the substrate, of a convex part of the concave-convex structure is L1, the maximum width of the top, far away from the substrate, of the convex part is L2, the height of the convex part is H, L1 / L2 is larger than or equal to 1.1 and smaller than or equal to 15: 1, and H / L1 is larger than or equal to 1.5 and smaller than or equal to 20: 1. The optical thin film provided by the invention has the advantages of wide spectrum, low reflectivity, low scattering and high laser damage threshold value, and can effectively improve the shooting definition and the laser damage resistance effect when being used in optical devices.

Description

Technical Field

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

[0002] Although the surface layer of the traditional multi-layer low-reflection film has a nano-subwavelength structure, the disordered arrangement of the nanostructure, the specific surface area of ​​the film layer is large and in a non-homogeneous state, causing the light to be refracted multiple times after entering the film layer, resulting in serious light scattering. In particular, as the incident angle of the light entering the film layer increases, the light scattering becomes more serious. Therefore, multiple lenses that use traditional multi-layer low-reflection films cumulatively have problems such as reduced imaging transparency and obvious fogging of the picture, which affects the clarity of the lens shooting. In addition, with the rapid popularization of driverless cars, most autonomous driving cars are equipped with laser radar as standard, and the damage of the laser in the laser radar to the film layer in the lens module cannot be ignored.

[0003] Therefore, there is an urgent need to develop an optical film that has wide spectrum, low reflectivity, low scattering, and a high laser damage threshold. Summary of the invention

[0004] Based on this, it is necessary to provide an optical film and its preparation method and application to address the above problems; the optical film also has wide spectrum low reflectivity, low scattering and a high laser damage threshold, and is used in optical devices to effectively improve the shooting clarity and anti-laser damage effect of the optical devices.

[0005] An optical film comprises a substrate, a dielectric film and a nanostructured surface layer which are stacked in sequence, wherein the material of the nanostructured surface layer is selected from fluorine-containing resin or nano-organic silicon, and the porosity of the nanostructured surface layer is 20%-91%;

[0006] Among them, the surface of the nanostructured surface layer away from the substrate has a concave-convex structure, and among the raised parts of the concave-convex structure, the maximum width of the bottom close to the substrate is L1, the maximum width of the top away from the substrate is L2, the height of the raised part is H, 1.1:1≤L1 / L2≤15:1, 1.5:1≤H / L1≤20:1.

[0007] In one of the embodiments, at least one nanostructured intermediate layer is provided between the dielectric film and the nanostructured surface layer, and the material of the nanostructured intermediate layer at least includes fluorine-containing resin or nano-organic silicon.

[0008] In one embodiment, the porosity of the nanostructure surface layer is greater than the porosity of the nanostructure middle layer;

[0009] And / or, when the nanostructured intermediate layer is multi-layered, the porosity of the nanostructured intermediate layer decreases layer by layer along the direction from the nanostructured surface layer to the substrate;

[0010] And / or, the total thickness of the nanostructure surface layer and the nanostructure middle layer is less than 500 nm.

[0011] In one embodiment, the dielectric film is a single-layer structure;

[0012] Alternatively, the dielectric film is a 2N-layer structure, the dielectric film comprises a first dielectric film and a second dielectric film alternately stacked, the substrate is attached to the first dielectric film, the refractive index of the first dielectric film is greater than the refractive index of the second dielectric film, and N is a positive integer;

[0013] Alternatively, the dielectric film is a 2N+1 layer structure, the dielectric film includes a third dielectric film and a fourth dielectric film alternately stacked, the substrate is attached to the third dielectric film, the refractive index of the third dielectric film is less than the refractive index of the fourth dielectric film, and N is a positive integer.

[0014] In one embodiment, the material of the dielectric film is selected from at least one of titanium pentoxide, tantalum pentoxide, H4 lanthanum titanate, silicon dioxide, aluminum oxide or a silicon-aluminum mixture.

[0015] In one embodiment, when the material of the nanostructured surface layer is selected from nano-organic silicon, the total content of silicon and oxygen in the nanostructured surface layer is greater than 80%.

[0016] In one embodiment, the material of the substrate is selected from glass or optical resin, and the refractive index of the substrate is 1.35-1.9.

[0017] In one embodiment, the equivalent refractive index of the optical film is 1.01-1.39.

[0018] A method for preparing the optical film as described above comprises the following steps:

[0019] Providing a substrate, and laminating a dielectric film on any surface of the substrate;

[0020] A first film layer is deposited on the surface of the dielectric film. -3 Under the vacuum pressure condition of Pa-10Pa, the first film layer is plasma etched to form a nanostructured surface layer to obtain the optical film, wherein the porosity of the first film layer is 9%-89%, and the material of the first film layer is selected from fluorine-containing resin or nano-silicon.

[0021] In one embodiment, at least one second film layer is first deposited on the surface of the dielectric film, and then the first film layer is deposited. After the first film layer or the second film layer is deposited, -3 Under a vacuum pressure of Pa-10Pa, at least the first film layer is plasma etched to form a nanostructured surface layer and a nanostructured intermediate layer, wherein the porosity of the second film layer is 9%-50%, and the material of the second film layer includes at least fluorine-containing resin or nano-silicon.

[0022] In one of the embodiments, before plasma etching, a protective layer with a thickness of less than 10 nm is prepared on the surface of the film layer to be etched, and the material of the protective layer is titanium oxide or silicon oxide.

[0023] An optical device comprises the optical film as described above.

[0024] The fluorine-containing resin or nano-silicon on the surface of the optical film described in the present invention is arranged unidirectionally from the inside to the outside to form a concave-convex structure with a special size, so that the optical film has a unique nano-structured surface layer. On the one hand, the inhomogeneous part of the nano-structured surface layer in the optical film is reduced, and the refraction path generated when the light is incident is reduced, which is beneficial to greatly reduce the reflection and scattering of light, thereby reducing the wide spectrum reflectivity and improving the haze effect; on the other hand, based on the special interference phenomenon unique to the nano-structured surface layer, it can not only effectively reduce the reflectivity of the laser radar in the 905nm band, but also has a significant low reflectivity effect for special lasers in the 1550nm band, thereby improving the laser damage threshold of the optical film. Further, the optical film described in the present invention is used in optical devices, which can effectively improve the shooting clarity and anti-laser damage effect of the optical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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 recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 is a schematic diagram of a cross-sectional structure of an optical film in one embodiment of the present invention;

[0027] Figure 2 is a schematic diagram of a cross-sectional structure of an optical film in another embodiment of the present invention;

[0028] Figure 3 This is a scanning electron microscope image of the surface of the first film layer obtained in Example 1;

[0029] Figure 4This is a scanning electron microscope image of the nanostructured surface layer in the optical film obtained in Example 1;

[0030] Figure 5 The elemental analysis spectrum of the nanostructured surface layer in the optical film obtained in Example 1;

[0031] Figure 6 This is a scanning electron microscope image of the surface of the first film layer obtained in Example 3;

[0032] Figure 7 This is a scanning electron microscope image of the nanostructured surface layer in the optical film obtained in Example 3;

[0033] Figure 8 This is a scanning electron microscope image of the surface film layer of the optical film obtained in Comparative Example 1;

[0034] Fig. 9 is a reflectivity performance comparison diagram, wherein A is a reflectivity change curve of the optical film prepared in Example 1, B is a reflectivity change curve of the optical film prepared in Example 3, and C is a reflectivity change curve of the optical film prepared in Comparative Example 1;

[0035] Fig.10 3 are comparison diagrams of fogging effects, wherein A is a diagram of the fogging effect of the optical film prepared in Comparative Example 1, and B is a diagram of the fogging effect of the optical film prepared in Example 1.

[0036] Wherein: 10, substrate; 20, dielectric film; 30, nanostructured surface layer; 40, nanostructured intermediate layer. DETAILED DESCRIPTION

[0037] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0039] Combination Figure 1As shown, an optical film provided by the present invention comprises a substrate 10, a dielectric film 20 and a nanostructured surface layer 30 which are stacked in sequence. The material of the nanostructured surface layer 30 is selected from fluorine-containing resin or nano-organic silicon, and the porosity of the nanostructured surface layer 30 is 20%-91%.

[0040] Among them, the surface of the nanostructured surface layer 30 away from the substrate 10 has a concave-convex structure, and among the raised parts of the concave-convex structure, the maximum width of the bottom close to the substrate 10 is L1, the maximum width of the top away from the substrate 10 is L2, and the height of the raised part is H, 1.1:1≤L1 / L2≤15:1, 1.5:1≤H / L1≤20:1.

[0041] The fluorine-containing resin or nano-silicon on the surface of the optical film described in the present invention is arranged unidirectionally from the inside to the outside to form a concave-convex structure with a special size, so that the optical film has a unique nano-structured surface layer 30. On the one hand, the inhomogeneous part of the nano-structured surface layer 30 in the optical film is reduced, and the refraction path generated when the light is incident is reduced, which is beneficial to greatly reduce the reflection and scattering of light, thereby reducing the wide spectrum reflectivity and improving the haze effect.

[0042] On the other hand, based on the special interference phenomenon unique to the nanostructured surface layer 30, it can not only effectively reduce the reflectivity of the 905nm laser radar band, but also has the effect of reducing the reflectivity of the special laser in the 1550nm band, thereby increasing the laser damage threshold of the optical film to as high as 10J / cm 2 -28J / cm 2 , and reduce the extinction coefficient so that the extinction coefficient is less than 0.01 at a wavelength of 550nm, and then the optical film of the present invention is used in optical devices, which can effectively improve the shooting clarity and anti-laser damage effect of the optical devices.

[0043] It can be understood that the specific shape of the protrusion structure can be columnar, trapezoidal, hill-shaped and other irregular shapes; L1 / L2 includes but is not limited to any one point value of 1:1, 1.5:1, 2.2:1, 2.6:1, 3.0:1, 3.5:1, 5:1, 10:1, 15:1 or a range value consisting of any two point values, preferably 1.1:1≤L1 / L2≤3.5:1; H / L1 includes but is not limited to any one point value of 1.5:1, 2.1:1, 2.4:1, 2.8:1, 3.0:1, 3.6:1, 5:1, 10:1, 15:1, 20:1 or a range value consisting of any two point values, preferably 1.5:1≤H / L1≤3:1.

[0044] Preferably, in the convex part of the concavo-convex structure, the maximum width L1 of the bottom close to the substrate 10 is 20nm-150nm, the maximum width L2 of the top away from the substrate 10 is 10nm-100nm, and the height H of the convex part is 50nm-400nm.

[0045] In one embodiment, when the material of the nanostructured surface layer 30 is selected from nano-organic silicon, the total content of silicon and oxygen in the nanostructured surface layer 30 is greater than 80%, which is close to the level of fused quartz material, which is conducive to further improving the anti-laser damage effect of the optical film and making the laser damage threshold reach 20J / cm 2 above.

[0046] It should be noted that the morphology of the nano-organic silicon (nSCH) includes but is not limited to solid or hollow spheres, solid or hollow ellipsoids, solid or hollow columns, solid or hollow particles, etc., and the size is preferably 10nm-100nm. When the nano-organic silicon is a hollow structure, by adjusting the wall thickness of the hollow structure, it is beneficial to further control the porosity of the nano-structure surface layer 30, so that the porosity of the nano-structure surface layer 30 can be flexibly adjusted.

[0047] In one embodiment, when the material of the nanostructured surface layer 30 is selected from fluorine-containing resin, since the water contact angle of the fluorine-containing resin material is greater than 100°, the optical film can have waterproof and anti-pollution effects, thereby preventing the optical device from being contaminated by glue, volatile organic compounds, etc.

[0048] Specifically, the fluorine-containing resin includes but is not limited to polytetrafluoroethylene, preferably polytetrafluoroethylene.

[0049] Combination Figure 2 As shown, a nanostructured intermediate layer 40 may be added between the dielectric film 20 and the nanostructured surface layer 30 , and the material of the nanostructured intermediate layer 40 at least includes fluorine-containing resin or nano-organic silicon.

[0050] It can be understood that the material of the nanostructured surface layer 30 and the nanostructured intermediate layer 40 can be the same or different; the material of the nanostructured intermediate layer 40 can be fluorine-containing resin or nano-silicon, or a mixed material consisting of fluorine-containing resin, nano-silicon and other materials, and preferably, the mass proportion of fluorine-containing resin or nano-silicon in the mixed material is higher than 80%.

[0051] In one embodiment, the porosity of the nanostructured surface layer 30 is greater than the porosity of the nanostructured intermediate layer 40. Preferably, the porosity difference between the nanostructured surface layer 30 and the nanostructured intermediate layer 40 is 10%-49%, which is conducive to achieving an equivalent refractive index gradient change of the nanostructure, and the nanostructured surface layer 30 has the lowest equivalent refractive index, including a sub-wavelength structure of 10nm-200nm, and also has a certain anti-reflectivity effect, thereby utilizing the combined structure of the nanostructured surface layer 30 and the nanostructured intermediate layer 40 to further achieve a lower reflectivity effect.

[0052] In one embodiment, when the nanostructured intermediate layer 40 is multi-layered, the porosity of the nanostructured intermediate layer 40 decreases layer by layer along the direction from the nanostructured surface layer 30 to the substrate 10. The combined structure of the multi-layer nanostructured intermediate layer 40 is conducive to further reducing the reflectivity.

[0053] Preferably, the nanostructured intermediate layer 40 has no more than three layers.

[0054] It can be understood that the surface of the nanostructured intermediate layer 40 away from the substrate may have a concave-convex structure or may be a relatively smooth surface, and the present invention does not limit this.

[0055] In one embodiment, the thickness of the nanostructured surface layer 30 is less than 500 nm, or the total thickness of the nanostructured surface layer 30 and the nanostructured intermediate layer 40 is less than 500 nm; in the nanostructured surface layer 30 and the nanostructured intermediate layer 40, the thickness of the nanostructured surface layer 30 and the nanostructured intermediate layer 40 are independently selected from 50 nm to 100 nm.

[0056] In one embodiment, the dielectric film 20 is a single-layer structure, and preferably the refractive index of the dielectric film 20 is 1.3-2.6.

[0057] In one embodiment, the dielectric film 20 is a 2N layer structure, and the dielectric film 20 includes a first dielectric film and a second dielectric film that are alternately stacked. The substrate 10 is bonded to the first dielectric film, and the refractive index of the first dielectric film is greater than the refractive index of the second dielectric film. Preferably, the refractive index of the first dielectric film is 1.6-2.6, and the refractive index of the second dielectric film is 1.3-1.6. It is further preferred that the refractive index of the first dielectric film differs from the refractive index of the second dielectric film by 0.3-1; N is a positive integer, preferably N=1 or 2.

[0058] It can be understood that, in the dielectric film 20 , along the direction away from the substrate 10 , the first dielectric film and the second dielectric film are stacked and alternately cyclically.

[0059] In one embodiment, when the dielectric film 20 is a 2N+1 layer structure, the dielectric film 20 includes a third dielectric film and a fourth dielectric film that are alternately stacked, the substrate 10 is bonded to the third dielectric film, the refractive index of the third dielectric film is less than the refractive index of the fourth dielectric film, preferably the refractive index of the third dielectric film is 1.3-1.6, and the refractive index of the fourth dielectric film is 1.6-2.6, and further preferably the refractive index of the third dielectric film differs from the refractive index of the fourth dielectric film by 0.3-1; N is a positive integer, preferably N=1 or 2.

[0060] It can be understood that, in the dielectric film 20 , along the direction away from the substrate 10 , the third dielectric film and the fourth dielectric film are stacked alternately in a cyclic manner.

[0061] Preferably, when the optical film does not contain the nanostructured intermediate layer 40, the dielectric film 20 preferably adopts at least a three-layer structure; when the optical film contains the nanostructured intermediate layer 40, the dielectric film 20 preferably adopts a single-layer structure, a double-layer structure or a three-layer structure.

[0062] In one embodiment, the material of the dielectric film 20 includes but is not limited to at least one of titanium pentoxide, tantalum pentoxide, H4 lanthanum titanate, silicon dioxide, aluminum oxide, or a silicon-aluminum mixture.

[0063] In one embodiment, the material of the substrate 10 is selected from glass or optical resin, and the refractive index of the substrate 10 is 1.35-1.9.

[0064] In one embodiment, the equivalent refractive index of the optical film is 1.01-1.39, preferably 1.03-1.26.

[0065] The present invention provides a method for preparing the optical film as described above, comprising the following steps:

[0066] S1, providing a substrate 10, and laminating a dielectric film 20 on any surface of the substrate 10;

[0067] S2, depositing a first film layer on the surface of the dielectric film 20, at 10 -3 Under the vacuum pressure condition of 10Pa-10Pa, the first film layer is plasma etched to form a nanostructured surface layer 30 to obtain the optical film, wherein the porosity of the first film layer is 9%-89%, and the material of the first film layer is selected from fluorine-containing resin or nano-silicon.

[0068] In step S1 , the present invention does not limit the method for preparing the dielectric film 20 , and existing methods such as physical vapor deposition (PVD) can be used.

[0069] Specifically, the material of the dielectric film 20 includes but is not limited to at least one of titanium pentoxide, tantalum pentoxide, lanthanum titanate, silicon dioxide, aluminum oxide or a silicon-aluminum mixture. The material of the substrate 10 is selected from glass or optical resin, and the refractive index of the substrate 10 is preferably 1.35-1.9.

[0070] In step S2, after depositing a fluorine-containing resin film layer or a nano-organic silicon film layer on the surface of the dielectric film 20, the vacuum pressure conditions of plasma etching are adjusted so that the film layer is etched in an atmosphere with a specific oxygen content, so that the fluorine-containing resin or nano-organic silicon in the first film layer is arranged unidirectionally from the inside to the outside, and has a concave-convex structure of a special size. At the same time, the film layer is controlled to have a specific porosity, so that the optical film has a wide spectrum of low reflectivity, low scattering and a higher laser damage threshold.

[0071] It should be noted that the present invention does not limit the deposition process, including but not limited to vacuum thermal evaporation coating, plasma enhanced chemical vapor deposition (PECVD), plasma enhanced atomic layer deposition (PEALD), and preferably uses vacuum thermal evaporation deposition, which can make the film material propagate from the evaporation source to the surface of the dielectric film 20 in a nearly straight line, which is beneficial to further reduce the heterogeneous proportion of the nanostructured surface layer 30. Specifically, vacuum thermal evaporation coating includes but is not limited to electron beam evaporation deposition coating or resist vacuum coating.

[0072] It is understandable that when depositing a film layer, the porosity of the deposited film layer can be further optimized and regulated by adjusting the gas flow rate in the deposition device, wherein the types of gas in the deposition device include but are not limited to oxygen and argon.

[0073] In one embodiment, at least one second film layer is first deposited on the surface of the dielectric film 20, and then the first film layer is deposited. After the first film layer or the second film layer is deposited, -3 Under the vacuum pressure condition of Pa-10Pa, at least the first film layer is plasma etched to form a nanostructured surface layer 30 and a nanostructured intermediate layer 40, wherein the porosity of the second film layer is 9%-50%, and the material of the second film layer includes at least fluorine-containing resin or nano-silicon.

[0074] It can be understood that in the present invention, the first film layer and the second film layer can be plasma etched, or only the first film layer can be plasma etched, that is, the second film layer located between the first film layer and the dielectric film 20 can be a film layer with a concave-convex structure on the surface formed by plasma etching, or it can be a relatively smooth film layer that has not been etched.

[0075] Preferably, when at least one second film layer is first deposited on the surface of the dielectric film 20 and then the first film layer is deposited, -3Under the vacuum pressure condition of 0.6 Pa-10 Pa, the first film layer is plasma etched to form a nanostructured surface layer 30 and a nanostructured intermediate layer 40 .

[0076] In one embodiment, before plasma etching, a protective layer is prepared on the surface of the film layer to be etched, wherein the protective layer is a discontinuous film with a thickness less than 10 nm, and the material of the protective layer is titanium oxide or silicon oxide.

[0077] The present invention also provides an optical device, including the optical film as described above. It can be understood that the optical device includes but is not limited to a lens module. The optical film described in the present invention is particularly suitable for use in a lens module and can effectively improve the lens shooting clarity and anti-laser damage effect.

[0078] The optical film, preparation method and application thereof will be further described below by the following specific examples. However, those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0079] Example 1

[0080] A resin substrate (refractive index is 1.51) is used as a substrate, and a layer of silicon dioxide dielectric film (refractive index is 1.46) is prepared on any surface of the resin substrate by a physical vapor deposition (PVD) vacuum coating process.

[0081] Using electron beam evaporation deposition coating process, a mixed material of silicon dioxide and hexamethyldisiloxane (the mass ratio of silicon dioxide to hexamethyldisiloxane is 1:2) is deposited on the surface of the silicon dioxide dielectric film to form a nanostructured intermediate layer (film thickness of about 85nm, porosity of about 30%), and then hexamethyldisiloxane is deposited as the first film layer (film thickness of about 90nm, porosity of about 51%). The scanning electron microscope image of the surface of the first film layer is shown in FIG. Figure 3 After a thin silicon dioxide protective layer was deposited on the surface of the first film layer by PVD, plasma etching was performed under a low vacuum pressure of 1 Pa to obtain an optical film. The scanning electron microscope image and elemental analysis spectrum of the nanostructured film layer on the surface of the optical film are shown in FIG. Figure 4 , Figure 5 shown.

[0082] Example 2

[0083] Glass is used as a substrate (refractive index is 1.52), and a layer of silicon dioxide dielectric film (refractive index is 1.46) is prepared on any surface of the glass substrate by a PVD vacuum coating process.

[0084] PECVD was used to deposit two layers of hexamethyldisiloxane on the surface of the silicon dioxide dielectric film, as a nanostructured intermediate layer (film thickness of about 100 nm, porosity of about 35%) and a first film layer (film thickness of about 120 nm, porosity of about 60%), and the first film layer was plasma etched under a low vacuum pressure of 0.1 Pa to obtain an optical thin film.

[0085] Example 3

[0086] Resin was used as a substrate (refractive index was 1.62), and three layers of silicon dioxide dielectric films were prepared on any surface of the resin by PVD vacuum coating process (the refractive indices of the three layers of silicon dioxide dielectric films were 1.46, 2.45, and 1.46, respectively, in the direction away from the substrate).

[0087] Using electron beam evaporation deposition coating technology, polytetrafluoroethylene is deposited on the surface of the silicon dioxide dielectric film as the first film layer (film thickness is about 170nm, porosity is about 50%). The scanning electron microscope image of the surface of the first film layer is as follows: Figure 6 After the first film layer was vacuum-plated with a titanium dioxide protective layer, -2 The optical film was obtained by plasma etching under low vacuum pressure of 1.5 Pa. The scanning electron microscope image of the nanostructured film layer on the surface of the optical film is shown in Figure 7 shown.

[0088] Example 4

[0089] Optical resin is used as a substrate (refractive index is 1.51), and six layers of silicon dioxide dielectric films are prepared on any surface of the optical resin by PVD vacuum coating process (the refractive indices of the six layers of silicon dioxide dielectric films are 2.45, 1.46, 2.45, 1.46, 2.45, and 1.46, respectively, in the direction away from the substrate).

[0090] The electron beam evaporation deposition coating process was used to deposit polytetrafluoroethylene as the first film layer on the surface of the silicon dioxide dielectric film (the film thickness was about 150nm and the porosity was about 45%). After the titanium dioxide protective layer was plated on the surface of the first film layer, the film was coated with a titanium dioxide protective layer. -2 Optical thin films are obtained by plasma etching under low vacuum pressure conditions of Pa.

[0091] Comparative Example 1

[0092] The difference between Comparative Example 1 and Example 1 is that the PVD process is used to directly deposit aluminum oxide on the surface of the silicon dioxide dielectric film, and then the optical nanofilm is obtained after reaction and drying with ultrapure water. The scanning electron microscope image of the surface film layer of the optical film is as follows: Figure 8 shown.

[0093] Comparative Example 2

[0094] The difference between Comparative Example 2 and Example 2 is that two layers of silicon dioxide are deposited on the surface of the silicon dioxide dielectric film by PECVD, which are respectively used as the first film layer (film thickness of about 90nm, porosity of about 5%) and the second film layer (film thickness of about 80nm, porosity of about 8%). -2 The first film layer is plasma etched under a low vacuum pressure condition of Pa to obtain an optical thin film.

[0095] Comparative Example 3

[0096] The difference between Comparative Example 3 and Example 2 is that at 5.0×10 -4 The first film layer is plasma etched under a vacuum pressure of Pa to obtain an optical thin film.

[0097] Examples 1 to 4 and Comparative Examples 1 to 3 were tested, and the results are as follows: Fig. 9 , Fig.10 As shown in Table 1 and Table 2.

[0098] Table 1

[0099]

[0100] Table 2

[0101]

[0102] Combination Fig. 9 , Fig.10 As can be seen from Tables 1 and 2, the optical film provided by the present invention has wide spectrum low reflectivity, low scattering and a high laser damage threshold, and can be used in optical devices to effectively improve shooting clarity and resistance to laser damage.

[0103] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An optical film, characterized in that: The optical film comprises a substrate, a dielectric film and a nanostructured surface layer which are stacked in sequence, wherein the material of the nanostructured surface layer is selected from fluorine-containing resin or nano-organic silicon, and the porosity of the nanostructured surface layer is 20%-91%; Among them, the surface of the nanostructured surface layer away from the substrate has a concave-convex structure, and among the raised parts of the concave-convex structure, the maximum width of the bottom close to the substrate is L1, the maximum width of the top away from the substrate is L2, the height of the raised part is H, 1.1:1≤L1 / L2≤15:1, 1.5:1≤H / L1≤20:

1.

2. The optical film according to claim 1, characterized in that: At least one nanostructured intermediate layer is provided between the dielectric film and the nanostructured surface layer, and the material of the nanostructured intermediate layer at least includes fluorine-containing resin or nano-organic silicon.

3. The optical film according to claim 2, characterized in that: The porosity of the nanostructure surface layer is greater than the porosity of the nanostructure middle layer; And / or, when the nanostructured intermediate layer is multi-layered, the porosity of the nanostructured intermediate layer decreases layer by layer along the direction from the nanostructured surface layer to the substrate; And / or, the total thickness of the nanostructure surface layer and the nanostructure middle layer is less than 500 nm.

4. The optical film according to claim 1, characterized in that: The dielectric film is a single-layer structure; Alternatively, the dielectric film is a 2N-layer structure, the dielectric film comprises a first dielectric film and a second dielectric film alternately stacked, the substrate is attached to the first dielectric film, the refractive index of the first dielectric film is greater than the refractive index of the second dielectric film, and N is a positive integer; Alternatively, the dielectric film is a 2N+1 layer structure, the dielectric film includes a third dielectric film and a fourth dielectric film alternately stacked, the substrate is attached to the third dielectric film, the refractive index of the third dielectric film is less than the refractive index of the fourth dielectric film, and N is a positive integer.

5. The optical film according to claim 1, characterized in that: The material of the dielectric film is selected from at least one of titanium pentoxide, tantalum pentoxide, H4 lanthanum titanate, silicon dioxide, aluminum oxide or a silicon-aluminum mixture.

6. The optical film according to claim 1, characterized in that: When the material of the nanostructured surface layer is selected from nano-organic silicon, the total content of silicon and oxygen in the nanostructured surface layer is greater than 80%.

7. The optical film according to claim 1, characterized in that: The material of the substrate is selected from glass or optical resin, and the refractive index of the substrate is 1.35-1.

9.

8. The optical film according to any one of claims 1 to 7, characterized in that: The equivalent refractive index of the optical film is 1.01-1.

39.

9. A method for preparing an optical film according to any one of claims 1 to 8, characterized in that: The steps include: Providing a substrate, and laminating a dielectric film on any surface of the substrate; A first film layer is deposited on the surface of the dielectric film. -3 Under the vacuum pressure condition of Pa-10Pa, the first film layer is plasma etched to form a nanostructured surface layer to obtain the optical film, wherein the porosity of the first film layer is 9%-89%, and the material of the first film layer is selected from fluorine-containing resin or nano-silicon.

10. The method for preparing an optical film according to claim 9, characterized in that: At least one second film layer is first deposited on the surface of the dielectric film, and then the first film layer is deposited. After the first film layer or the second film layer is deposited, -3 Under a vacuum pressure of Pa-10Pa, at least the first film layer is plasma etched to form a nanostructured surface layer and a nanostructured intermediate layer, wherein the porosity of the second film layer is 9%-50%, and the material of the second film layer includes at least fluorine-containing resin or nano-silicon.

11. The method for preparing an optical film according to claim 9 or claim 10, characterized in that: Before plasma etching, a protective layer is prepared on the surface of the film layer to be etched, with a thickness of less than 10 nm, and the material of the protective layer is selected from titanium oxide or silicon oxide.

12. An optical device, characterized in that: The optical film comprises the optical film according to any one of claims 1 to 8.

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