Ultra-wide-angle hemispherical lens antireflection film and plating method thereof

Abstract

According to the ultra-wide-angle hemispherical lens antireflection film and the plating method thereof, hafnium oxide and magnesium fluoride are adopted as coating materials, and low-refractive-index MgF2 is adopted on the premise that the requirement of a spectrum curve is met, so that the reflectivity of the whole bandwidth can be reduced to the maximum extent, the low reflectivity can still be ensured while the bandwidth is widened, and the ultra-wide-angle hemispherical lens antireflection film has the advantages of being high in reflectivity, high in reflectivity and high in reflectivity. And the film layer stress can be reduced, and the film cracking risk is reduced. The ultra-wide-angle hemispherical lens is coated with the anti-reflection film, the problem that the anti-reflection film cannot achieve the anti-reflection effect due to the fact that the thickness of the center and the thickness of the edge of the lens are not uniform is solved, the requirement of a spectrum curve is met, meanwhile, the surface shape precision of an optical element after film coating is considered, and the edge and the center of the optical element can meet the use requirement.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to an ultra-wide-angle hemispherical lens anti-reflection film and a coating method thereof. Background Art

[0002] Optical thin films are indispensable components of modern optical systems and play a vital role in optical instruments. With the development of optical products, optical lenses are increasingly used. High-definition, wide-angle, and starlight-level lenses are all developing towards large numerical apertures and large light throughput, so lens coating is very important.

[0003] During the coating process, due to the different deposition angles of the film material vapor generated by the point source, there are certain differences in the film thickness at each point on the same lens surface. This has little effect on lenses with smaller curvatures, but for lenses with larger curvatures, especially lenses that are nearly hemispherical, the film thickness at the edge and the center is very different. The thickness of the edge film layer is much thinner than that of the center, causing the entire spectrum to move toward short waves. When light is incident from the edge and the waist, the film layer on the surface of the lens cannot play an anti-reflection role, but causes reflection, resulting in a serious reduction in the overall luminous flux in the imaging system, resulting in poor imaging quality. In severe cases, multiple reflections appear on the surface of the lens, forming "ghost images" and affecting the performance of the entire lens. Therefore, an effective solution is urgently needed to solve the above problems. Summary of the invention

[0004] The present invention provides an anti-reflection film for an ultra-wide-angle hemispherical lens and a coating method thereof, so as to solve the defect in the prior art that the anti-reflection film cannot play an anti-reflection role due to uneven thickness at the center and edge of the lens, and achieve the requirement of ensuring the spectral curve while taking into account the surface accuracy of the optical element after coating, so that the use requirements can be met regardless of the edge or center position.

[0005] The invention provides an ultra-wide-angle hemispherical lens anti-reflection film, which consists of a hafnium dioxide film layer and a magnesium fluoride film layer plated on the ultra-wide-angle hemispherical lens.

[0006] According to an ultra-wide-angle hemispherical lens anti-reflection film provided by the present invention, the hafnium dioxide film layer and the magnesium fluoride film layer are, in order from near to far from the ultra-wide-angle hemispherical lens, a first hafnium dioxide film layer, a first magnesium fluoride film layer, a second hafnium dioxide film layer, and a second magnesium fluoride film layer.

[0007] The present invention also provides a method for coating the anti-reflection film for the ultra-wide-angle hemispherical lens, comprising:

[0008] Use the Hall ion source to etch the base film layer of the ultra-wide-angle hemispherical lens for 10-15 minutes, and keep the background vacuum degree below 2*10 -3Pascal, deposition temperature is 250-320 degrees Celsius, constant temperature for 10-20 minutes;

[0009] The ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer is plated on the surface of the ultra-wide-angle hemispherical lens.

[0010] According to a method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens provided by the present invention, the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer is coated on the surface of the ultra-wide-angle hemispherical lens, comprising:

[0011] The edge of the ultra-wide-angle hemispherical lens is clamped by a metal fixture of a planetary fixture, so that the concave surface of the ultra-wide-angle hemispherical lens is vertically downward; the primary planetary disk of the planetary fixture is set to rotate at a first angular velocity, and the secondary planetary disk of the planetary fixture is set to rotate at a second angular velocity; the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer is plated on the concave surface;

[0012] The metal fixture of the planetary fixture is used to clamp the edge of the ultra-wide-angle hemispherical lens so that the convex surface of the ultra-wide-angle hemispherical lens is vertically downward; the ultra-wide-angle hemispherical lens is adjusted according to the set inclination; the first-level planetary disk of the planetary fixture is set to rotate at a first angular velocity, and the second-level planetary disk of the planetary fixture is set to rotate at a third angular velocity; and the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer is plated on the convex surface.

[0013] According to a method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens provided by the present invention, before adjusting the ultra-wide-angle hemispherical lens according to a set inclination, the method further comprises:

[0014] Obtaining the length and outer diameter of the ultra-wide-angle hemispherical lens, and determining half of the outer diameter as the radius of the ultra-wide-angle hemispherical lens;

[0015] The set inclination is obtained based on the following formula:

[0016] θ=arctan(L / H)

[0017] Wherein, θ is the inclination, L is the length, and H is the radius.

[0018] According to a method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens provided by the present invention, before the secondary planetary disk of the planetary fixture is arranged to rotate at a third angular velocity, the method further comprises:

[0019] The third angular velocity is obtained based on the following formula:

[0020] ω2=ω1 / cosθ

[0021] Wherein, ω2 is the third angular velocity, θ is the inclination, and ω1 is the second angular velocity.

[0022] According to a method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens provided by the present invention, before coating the anti-reflection film for the ultra-wide-angle hemispherical lens composed of a hafnium dioxide film layer and a magnesium fluoride film layer on the surface of the ultra-wide-angle hemispherical lens, the method further comprises:

[0023] Obtaining a plating ratio parameter and a plating target corresponding to the ultra-wide-angle hemispherical lens;

[0024] According to the plating target and the plating ratio parameter, determining the target plating thickness of the hafnium dioxide film layer and the target plating thickness of the magnesium fluoride film layer respectively;

[0025] The method of coating the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer on the surface of the ultra-wide-angle hemispherical lens comprises:

[0026] The ultra-wide-angle hemispherical lens anti-reflection film is plated on the surface of the ultra-wide-angle hemispherical lens according to the target coating thickness of the hafnium dioxide film layer and the target coating thickness of the magnesium fluoride film layer.

[0027] According to a method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens provided by the present invention, the coating ratio parameter includes a first coating ratio parameter corresponding to the hafnium dioxide film layer and a second coating ratio parameter corresponding to the magnesium fluoride film layer;

[0028] The step of determining the target plating thickness of the hafnium dioxide film layer and the target plating thickness of the magnesium fluoride film layer respectively according to the plating target and the plating ratio parameter comprises:

[0029] Performing simulation analysis based on the plating target to determine a simulated plating thickness of the hafnium dioxide film layer and a simulated plating thickness of the magnesium fluoride film layer;

[0030] The product of the simulated plating thickness of the hafnium dioxide film layer and the first plating ratio parameter is determined as the target plating thickness of the hafnium dioxide film layer, and the product of the simulated plating thickness of the magnesium fluoride film layer and the second plating ratio parameter is determined as the target plating thickness of the magnesium fluoride film layer.

[0031] According to a method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens provided by the present invention, the step of obtaining a coating ratio parameter comprises:

[0032] Obtain a first lens and a second lens made of the same base material as the ultra-wide-angle hemispherical lens;

[0033] A hafnium dioxide film layer of a first set thickness is deposited on the surface of the first lens, and a magnesium fluoride film layer of a second set thickness is deposited on the surface of the second lens, wherein the first set thickness and the second set thickness are 150-300 nanometers;

[0034] Performing simulation analysis on the plated first lens to determine the simulated plated thickness of the hafnium dioxide film layer on the first lens, and performing simulation analysis on the plated second lens to determine the simulated plated thickness of the magnesium fluoride film layer on the second lens;

[0035] The ratio of the first set thickness to the simulated coating thickness of the hafnium dioxide film layer on the first lens is determined as a first coating ratio parameter corresponding to the hafnium dioxide film layer, and the ratio of the second set thickness to the simulated coating thickness of the magnesium fluoride film layer on the second lens is determined as a second coating ratio parameter corresponding to the magnesium fluoride film layer.

[0036] According to a method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens provided by the present invention, the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer is coated on the surface of the ultra-wide-angle hemispherical lens, comprising:

[0037] When plating the hafnium dioxide film layer, the deposition rate is controlled to be 0.2-0.4 nanometers per second, the oxygen filling amount is 15-25 standard cubic centimeters per minute, the ion source anode voltage is 230-280 volts, and the current is 5-7 amperes;

[0038] When the magnesium fluoride film is plated, the deposition rate is controlled to be 0.4-0.6 nanometers per second, the current is 20-30 amperes, and the magnesium fluoride is formed into a film by electron gun evaporation.

[0039] The ultra-wide-angle hemispherical lens anti-reflection film and the coating method thereof provided by the present invention use hafnium dioxide and magnesium fluoride as coating materials, and use low-refractive-index MgF2 while ensuring the requirements of the spectral curve, which can reduce the reflectivity of the entire bandwidth to the maximum extent, while still ensuring a low reflectivity while widening the bandwidth, and can reduce the stress of the film layer and reduce the risk of film cracking. The anti-reflection film is coated on the ultra-wide-angle hemispherical lens, which solves the problem that the anti-reflection film cannot play an anti-reflection role due to the uneven thickness of the center and edge of the lens. While ensuring the requirements of the spectral curve, the surface accuracy of the optical element after coating is taken into account, so that it can meet the requirements of use regardless of the edge or the center position. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 The present invention is a schematic diagram of the process of coating an anti-reflection film for an ultra-wide-angle hemispherical lens.

[0042] Figure 2 It is a schematic diagram of the concave surface plating of the ultra-wide-angle hemispherical lens provided by the present invention.

[0043] Figure 3 It is a schematic diagram of the convex surface plating of the ultra-wide-angle hemispherical lens provided by the present invention.

[0044] Figure 4 It is a schematic structural diagram of the ultra-wide-angle hemispherical lens provided by the present invention.

[0045] Figure 5 It is a schematic diagram of the dimensions of the ultra-wide-angle hemispherical lens provided by the present invention.

[0046] Figure 6 It is a schematic diagram of the residual reflectivity at an incident angle of 0° provided by the present invention.

[0047] Figure 7 It is a schematic diagram of the residual reflectivity at an incident angle of 30° provided by the present invention.

[0048] Figure 8 It is a schematic diagram of the residual reflectivity at an incident angle of 50° provided by the present invention.

[0049] Fig. 9 It is the measured coating curve diagram provided by the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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.

[0051] Combine the following Figure 1-Figure 9 The invention describes an anti-reflection film for an ultra-wide-angle hemispherical lens and a coating method thereof.

[0052] In order to more clearly understand the technical solutions of the embodiments of the present invention, some technical contents related to the embodiments of the present invention are first introduced.

[0053] Hafnium dioxide is an inorganic substance with the chemical formula HfO2, which is an oxide of the element hafnium.

[0054] Magnesium fluoride is a compound of the halogen element fluorine and the metallic element magnesium, with the chemical formula being MgF2.

[0055] Vacuum evaporation: referred to as evaporation, refers to a process in which a certain heating evaporation method is used to evaporate the coating material (or film material) under vacuum conditions and gasify it, so that the particles fly to the surface of the substrate and condense into a film. Evaporation is an earlier and more widely used vapor deposition technology, with the advantages of simple film formation method, high film purity and density, and unique film structure and performance.

[0056] Coating fixture: It plays the role of supporting optical components during the vacuum evaporation process of optical components, such as planetary fixtures. Unlike optical components, coating fixtures are usually made of metal materials, such as aluminum alloy, stainless steel, etc.

[0057] At present, in the process of film deposition, the main methods used are correction baffles, planetary fixtures that revolve and rotate, and film system design to widen the bandwidth in the long-wave direction of the curve to improve the uniformity of film thickness.

[0058] However, adding a correction baffle can only improve the film thickness distribution on the entire workpiece disk, but cannot correct the film thickness of a single lens at different positions on the workpiece disk. The method of changing the uniformity of lens film thickness by widening the curve bandwidth through film system design is only applicable to lenses with smaller curvatures. For hemispherical lenses with larger curvatures, their edge positions are almost parallel to the evaporation direction of the film material, resulting in very little film thickness at the edge positions and poor uniformity.

[0059] An embodiment of the present invention provides an ultra-wide-angle hemispherical lens anti-reflection film, wherein the ultra-wide-angle hemispherical lens anti-reflection film is composed of a HfO2 film layer and a MgF2 film layer coated on the ultra-wide-angle hemispherical lens.

[0060] Among them, the ultra-wide-angle hemispherical lens can be a lens with a curvature equivalent to the aperture, or can be other lenses; the anti-reflection film of the ultra-wide-angle hemispherical lens can include at least one HfO2 film layer and at least one MgF2 film layer.

[0061] This embodiment adopts high refractive index material HfO2 and low refractive index material HfO2 as coating materials, while ensuring the requirements of the spectral curve. At the same time, the film system adopts MgF2, which can minimize the reflectivity of the entire bandwidth, while widening the bandwidth and still ensuring a low reflectivity, and can reduce the stress of the film layer and reduce the risk of film cracking.

[0062] In one or more optional embodiments of the present invention, the anti-reflection film of the ultra-wide-angle hemispherical lens includes two HfO2 film layers (a first HfO2 film layer and a second HfO2 film layer) and two MgF2 film layers (a first MgF2 film layer and a second MgF2 film layer). Accordingly, the HfO2 film layer and the MgF2 film layer are, in order from near to far from the ultra-wide-angle hemispherical lens, the first HfO2 film layer, the first MgF2 film layer, the second HfO2 film layer and the second MgF2 film layer.

[0063] In this embodiment, the high refractive index material HfO2 and the low refractive index material MgF2 are matched and cross-plated. In order to ensure the requirements of the spectral curve, the outermost layer of the film system uses low refractive index MgF2, which can reduce the reflectivity of the entire bandwidth to the maximum extent, and can still ensure a low reflectivity while widening the bandwidth, and can reduce the stress of the film layer and reduce the risk of film cracking. At the same time, it can ensure that the transmission phase difference of the film system is less than 1 degree, which guarantees the imaging quality after assembly to a certain extent.

[0064] Figure 1 Schematic diagram of the process of coating the anti-reflection film of the ultra-wide-angle hemispherical lens provided by the present invention, such as Figure 1 As shown, the method includes the following:

[0065] Step 101: Use the Hall ion source to etch the base film layer of the ultra-wide-angle hemispherical lens for 10-15 minutes (min), and keep the background vacuum degree lower than 2*10 -3 Pascal (Pa), deposition temperature is 250-320 degrees Celsius (℃), constant temperature for 10-20 minutes.

[0066] In practical applications, in order to ensure the success rate of anti-reflection coating of ultra-wide-angle hemispherical lenses, it is necessary to pre-treat the ultra-wide-angle hemispherical lenses before coating. That is, before coating each layer of the anti-reflection film, the previous base film layer must be etched for 10-15 minutes using a Hall ion source, and the background vacuum must be kept below 2E-3Pa before coating, and the deposition temperature must be 250-320℃ for 10-20 minutes.

[0067] Step 102: coating the ultra-wide-angle hemispherical lens anti-reflection film composed of a HfO2 film layer and a MgF2 film layer on the surface of the ultra-wide-angle hemispherical lens.

[0068] After pre-processing the ultra-wide-angle hemispherical lens, the ultra-wide-angle hemispherical lens can be fixed with a coating fixture, and then HfO2 film and MgF2 film layers are coated on the surface (convex surface and concave surface) of the ultra-wide-angle hemispherical lens, that is, the ultra-wide-angle hemispherical lens anti-reflection coating.

[0069] Among them, the anti-reflection film of the ultra-wide-angle hemispherical lens can be plated by ion source assisted deposition electron beam evaporation method or vacuum evaporation method.

[0070] Preferably, a first HfO2 film layer, a first MgF2 film layer, a second HfO2 film layer and a second MgF2 film layer may be sequentially plated on the surface of the ultra-wide-angle hemispherical lens.

[0071] In one or more optional embodiments of the present invention, the ultra-wide-angle hemispherical lens anti-reflection film composed of a HfO2 film layer and a HfO2 film layer is plated on the surface of the ultra-wide-angle hemispherical lens, comprising:

[0072] The edge of the ultra-wide-angle hemispherical lens is clamped by a metal fixture of a planetary fixture, so that the concave surface of the ultra-wide-angle hemispherical lens is vertically downward; the primary planetary disk of the planetary fixture is set to rotate at a first angular velocity ω, and the secondary planetary disk of the planetary fixture is set to rotate at a second angular velocity ω1; the ultra-wide-angle hemispherical lens anti-reflection film composed of a HfO2 film layer and a MgF2 film layer is plated on the concave surface;

[0073] The metal fixture of the planetary fixture is used to clamp the edge of the ultra-wide-angle hemispherical lens so that the convex surface of the ultra-wide-angle hemispherical lens is vertically downward; the ultra-wide-angle hemispherical lens is adjusted according to the set inclination θ; the first-level planetary disk of the planetary fixture is set to rotate at a first angular velocity ω, and the second-level planetary disk of the planetary fixture is set to rotate at a third angular velocity ω2; the ultra-wide-angle hemispherical lens anti-reflection film composed of a HfO2 film layer and a MgF2 film layer is plated on the convex surface.

[0074] See also Figure 2 , Figure 2 This is a schematic diagram of the concave surface plating of the ultra-wide-angle hemispherical lens provided by the present invention. The concave surface of the plating surface of the ultra-wide-angle hemispherical lens is located directly below, and the metal fixture of the planetary fixture that revolves and rotates is used to support its edge to expose the concave surface. At the same time, the ultra-wide-angle hemispherical lens rotates ω1 under the secondary planetary disk, and rotates and revolves under the primary planetary disk, thereby obtaining a good uniformity of the film layer, which plays a certain role in ensuring the surface shape.

[0075] See also Figure 3 , Figure 3 Schematic diagram of the convex surface coating of the ultra-wide-angle hemispherical lens provided by the present invention. Since the convex surface of the ultra-wide-angle hemispherical lens is too convex, in order to ensure the uniformity of the film layer on the entire surface, the following is adopted: Figure 3 Method: After the ultra-wide-angle hemispherical lens is fixed by a metal fixture, it is tilted at a certain angle θ, and at the same time it rotates around its own central axis at a speed of ω2, and at the same time it rotates and revolves under the revolution of the first-level planetary disk ω, so as to obtain good film uniformity.

[0076] In one or more optional embodiments of the present invention, before adjusting the ultra-wide-angle hemispherical lens according to the set inclination, the method further includes:

[0077] Obtaining the length and outer diameter of the ultra-wide-angle hemispherical lens, and determining half of the outer diameter as the radius of the ultra-wide-angle hemispherical lens;

[0078] The set inclination is obtained based on the following formula:

[0079] θ=arctan(L / H)

[0080] Wherein, θ is the inclination, L is the length, and H is the radius.

[0081] Specifically, see Figure 4 , Figure 4 : is a schematic diagram of the structure of the ultra-wide-angle hemispherical lens provided by the present invention: L is the length of the ultra-wide-angle hemispherical lens, that is, the distance between the center of the convex surface and the center of the concave surface, in millimeters (mm), such as the center thickness of the lens. H is the radius of the ultra-wide-angle hemispherical lens, that is, half of the outer diameter of the ultra-wide-angle hemispherical lens. θ is the diagonal of the length of the ultra-wide-angle hemispherical lens.

[0082] In order to ensure the uniformity of the film layer when the convex surface is plated, the inclination θ needs to be determined according to the size of the ultra-wide-angle hemispherical lens. The inclination θ is equal to the diagonal of the length of the ultra-wide-angle hemispherical lens. Therefore, the ratio of the length and radius of the ultra-wide-angle hemispherical lens can be calculated first, and the ratio is input into the inverse tangent function to calculate the inclination θ.

[0083] In one or more optional embodiments of the present invention, before setting the secondary planetary disk of the planetary fixture to rotate at the third angular velocity, the method further includes:

[0084] The third angular velocity is obtained based on the following formula:

[0085] ω2=ω1 / cosθ

[0086] Among them, ω2 is the third angular velocity, θ is the inclination, and ω2 is the second angular velocity.

[0087] Specifically, in order to ensure the uniformity of the film layer when the convex surface is plated, the rotation speed (third angular velocity) ω2 of the secondary planetary disk (ultra-wide-angle hemispherical lens) can be determined according to the inclination θ and the second angular velocity ω1, that is, the cosine value of the inclination θ is first calculated, and then the ratio of the second angular velocity ω1 to the cosine value is determined as the third angular velocity ω2.

[0088] It should be noted that, since the inclination θ is determined according to the size of the ultra wide-angle hemispherical lens, and the third angular velocity ω2 is determined according to the inclination θ and the second angular velocity ω1, it can be considered that the third angular velocity ω2 is determined according to the size of the ultra wide-angle hemispherical lens and the second angular velocity ω1.

[0089] In one or more optional embodiments of the present invention, before coating the ultra-wide-angle hemispherical lens anti-reflection film composed of a HfO2 film layer and a MgF2 film layer on the surface of the ultra-wide-angle hemispherical lens, the method further includes:

[0090] Obtaining a plating ratio parameter and a plating target corresponding to the ultra-wide-angle hemispherical lens;

[0091] According to the plating target and the plating ratio parameter, respectively determining the target plating thickness of the HfO2 film layer and the target plating thickness of the MgF2 film layer;

[0092] The ultra-wide-angle hemispherical lens anti-reflection film composed of a HfO2 film layer and a MgF2 film layer is plated on the surface of the ultra-wide-angle hemispherical lens, comprising:

[0093] According to the target coating thickness of the HfO2 film layer and the target coating thickness of the MgF2 film layer, the ultra-wide-angle hemispherical lens anti-reflection film is coated on the surface of the ultra-wide-angle hemispherical lens.

[0094] Specifically, the coating ratio parameter (Tooling) refers to the ratio of the actual coating thickness (actual thickness) to the simulated coating thickness (design thickness), wherein the simulated coating thickness refers to the thickness of the film layer coated for the ultra-wide-angle hemispherical lens in the software during software simulation. The coating target refers to the optical parameters and surface parameters of the optical element formed by coating the anti-reflection film for the ultra-wide-angle hemispherical lens. The target coating thickness refers to the actual thickness of the film layer to be coated for the ultra-wide-angle hemispherical lens, that is, the actual coating thickness.

[0095] In practical applications, the plating ratio parameter and the plating target corresponding to the ultra-wide-angle hemispherical lens can be obtained first, wherein HfO2 and MgF2 can share a plating ratio parameter or correspond to their own plating ratio parameters respectively. The plating ratio parameter can be pre-set or calculated according to actual conditions. The present invention is not limited to this.

[0096] Then, simulation, analysis and calculation are performed based on the plating target and the plating ratio parameters to obtain the target plating thickness of the HfO2 film layer and the target plating thickness of the MgF2 film layer.

[0097] It should be noted that there may be more than one HfO2 film layer and MgF2 film layer in the ultra-wide-angle hemispherical lens anti-reflection film. When determining the target coating thickness, the target coating thickness of each HfO2 film layer and the target coating thickness of each MgF2 film layer must be determined separately.

[0098] On the basis of obtaining the target coating thickness of the HfO2 film layer and the target coating thickness of the MgF2 film layer, further, according to the target coating thickness of the HfO2 film layer and the target coating thickness of the MgF2 film layer and the coating order of each film layer, the HfO2 film layer and the MgF2 film layer are coated on the surface of the ultra-wide-angle hemispherical lens.

[0099] In this embodiment, the target coating thickness is determined by the coating ratio parameter and the coating target, and then the anti-reflection film of the ultra-wide-angle hemispherical lens is coated, which can not only ensure the accuracy of the anti-reflection film, but also improve the optical accuracy of the optical element based on the anti-reflection film.

[0100] In one or more optional embodiments of the present invention, the plating ratio parameter includes a first plating ratio parameter corresponding to the HfO2 film layer and a second plating ratio parameter corresponding to the MgF2 film layer; accordingly, determining the target plating thickness of the HfO2 film layer and the target plating thickness of the MgF2 film layer according to the plating target and the plating ratio parameter, respectively, includes:

[0101] Performing simulation analysis based on the plating target to determine the simulated plating thickness of the HfO2 film layer and the simulated plating thickness of the MgF2 film layer;

[0102] The product of the simulated plating thickness of the HfO2 film layer and the first plating ratio parameter is determined as the target plating thickness of the HfO2 film layer, and the product of the simulated plating thickness of the MgF2 film layer and the second plating ratio parameter is determined as the target plating thickness of the MgF2 film layer.

[0103] In practical applications, in order to further ensure the accuracy of the anti-reflection film, different types of film layers correspond to their own coating ratio parameters.

[0104] On the basis of obtaining the coating target, the coating target can be simulated through the film system software, and the coating of the anti-reflection film on the ultra-wide-angle hemispherical lens can be simulated in the film system software to achieve the coating target. When the coating target is achieved, the simulated coating thickness of the HfO2 film layer and the simulated coating thickness of the MgF2 film layer in the film system software are read.

[0105] Furthermore, the simulated plating thickness of the HfO2 film layer is multiplied by the first plating ratio parameter to obtain the target plating thickness of the HfO2 film layer, and the simulated plating thickness of the MgF2 film layer is multiplied by the second plating ratio parameter to obtain the target plating thickness of the MgF2 film layer.

[0106] In one or more optional embodiments of the present invention, the specific implementation process of obtaining the plating ratio parameter may be as follows:

[0107] Obtain a first lens and a second lens made of the same base material as the ultra-wide-angle hemispherical lens;

[0108] A HfO2 film layer with a first set thickness is plated on the surface of the first lens, and a MgF2 film layer with a second set thickness is plated on the surface of the second lens, wherein the first set thickness and the second set thickness are 150-300 nanometers;

[0109] Performing simulation analysis on the plated first lens to determine the simulated plated thickness of the HfO2 film layer on the first lens, and performing simulation analysis on the plated second lens to determine the simulated plated thickness of the MgF2 film layer on the second lens;

[0110] The ratio of the first set thickness to the simulated coating thickness of the HfO2 film layer on the first lens is determined as the first coating ratio parameter corresponding to the HfO2 film layer, and the ratio of the second set thickness to the simulated coating thickness of the MgF2 film layer on the second lens is determined as the second coating ratio parameter corresponding to the MgF2 film layer.

[0111] Specifically, the first lens and the second lens may be two identical plane mirrors. The first set thickness and the second set thickness may be the same or different, wherein the first set thickness is the actual coating thickness of the HfO2 film layer on the first lens, and the second set thickness is the actual coating thickness of the MgF2 film layer on the second lens.

[0112] In practical applications, in order to ensure the accuracy of the coating ratio parameters, the coating ratio parameters can be obtained through actual experiments, that is, the coating ratio parameters are obtained by coating a film layer on other lenses. Furthermore, in order to ensure the reliability of the coating ratio parameters, it is necessary to perform coating on the first lens and the second lens of the same base material as the ultra-wide-angle hemispherical lens to obtain the first coating ratio parameter and the second coating ratio parameter.

[0113] Specifically, a HfO2 film layer of a first set thickness is coated on the surface of the first lens, and a MgF2 film layer of a second set thickness is coated on the surface of the second lens. Then, the first lens coated with the HfO2 film layer is simulated and analyzed using the film system software to determine the simulated coating thickness of the HfO2 film layer on the first lens, and the second lens coated with the MgF2 film layer is simulated and analyzed using the film system software to determine the simulated coating thickness of the MgF2 film layer on the second lens.

[0114] Further, the first set thickness is divided by the simulated coating thickness of the HfO2 film layer on the first lens to obtain a first coating ratio parameter corresponding to the HfO2 film layer, and the second set thickness is divided by the simulated coating thickness of the MgF2 film layer on the second lens to obtain a second coating ratio parameter corresponding to the MgF2 film layer.

[0115] In one or more optional embodiments of the present invention, the ultra-wide-angle hemispherical lens anti-reflection film composed of a HfO2 film layer and a MgF2 film layer is plated on the surface of the ultra-wide-angle hemispherical lens, comprising:

[0116] When plating the HfO2 film, the deposition rate is controlled to be 0.2-0.4 nanometers per second (nm / s), the oxygen filling amount is 15-25 standard cubic centimeters per minute (SCCM), the ion source anode voltage is 230-280 volts (V), and the current is 5-7 amperes (A);

[0117] When the MgF2 film is plated, the deposition rate is controlled to be 0.4-0.6 nm / s, the current is 20-30 A, and the MgF2 film is formed by electron gun evaporation.

[0118] In practical applications, in order to ensure the stability of the HfO2 film and the rapidity of the coating, when coating each HfO2 film, the deposition rate is controlled to be 0.2-0.4nm / s, the oxygen filling amount is 15-25SCCM, the ion source anode voltage is 230-280V, and the current is 5-7A. In order to ensure the stability of the MgF2 film and the rapidity of the coating, when coating each MGF2 film, the deposition rate is controlled to be 0.4-0.6nm / s, the current is 20-30A, and the film is formed by electron gun evaporation.

[0119] The coating method of the anti-reflection film for the ultra-wide-angle hemispherical lens provided by the present invention is further described below with reference to specific examples.

[0120] First, obtain the ultra-wide-angle hemispherical lens, that is, the incoming material.

[0121] Figure 5 Schematic diagram of the size of the ultra-wide-angle hemispherical lens provided by the present invention. Figure 5 From the main view, section AA and section BB in the figure, we can see that the angle and angle tolerance of the main viewing groove of the ultra-wide-angle hemispherical lens are The dimensional tolerance of the bottom groove is The angle and angle tolerance of the left viewing slot are The curvature radius (SR) of surface 1 is 20.280±0.0003, the curvature radius (SR) of surface 2 is 15.735±0.0003, the center thickness is 15.91±0.001, the symmetry is 0.05, and the outer diameter (φ) is The inner diameter (φ) is 20.60±0.02. The coating objectives of the ultra-wide-angle hemispherical lens have two curve index requirements and surface shape requirements. The curve index requirements are: R <1.5%@355±2nm, O±50 degrees (deg), and the transmission phase difference of the film system is less than 1°. It means that the single-sided residual reflectivity of the film system needs to be less than 1.5%, the band is 353-357nm, the incident angle is 0-50°, and the transmission phase difference of the film system needs to be less than 1°. The surface shape requirements are that within the effective aperture, the surface shape (RMS) of one surface (convex surface) is better than 20nm, preferably 15nm, and the RMS of the two surfaces (concave surface) is better than 8nm.

[0122] Then, the plating ratio parameters are obtained. As shown in Table 1, the film system is designed and plated by using two film materials, HfO2 and MgF2, wherein the plating ratio parameters of HfO2 and MgF2 are obtained before plating, and the surfaces of the same substrate material as the element (the first lens and the second lens) are plated with set thicknesses of HfO2 and MgF2 respectively through the set process conditions. For example, the set thickness is 150nm, that is, the actual thickness of HfO2 and MgF2 is 150nm. Through the simulation analysis of the film system software, it is obtained that the simulated plating thickness (design thickness) of HfO2 is 170nm, and the design thickness of MgF2 is 138nm, thereby obtaining the plating ratio parameters (Tooling) of HfO2 to be 0.882 and the plating ratio parameters of MgF2 to be 1.087.

[0123] Table 1

[0124] Material Design thickness nm Actual thickness nm Plating ratio parameters <![CDATA[HfO2]]> 170 150 0.882 <![CDATA[MgF2]]> 138 150 1.087

[0125] See Table 2, which is Figure 5 The anti-reflection film designed for the ultra-wide-angle hemispherical lens is cross-plated by matching the high-refractive index material HfO2 with the low-refractive index material MgF2. The optical thickness of the film layer is 0.24 times, 0.13 times, 0.83 times and 0.68 times of L / 4 (one quarter of the wavelength), respectively, thus meeting the spectral requirements of the curve.

[0126] Table 2 Film design of ultra-wide-angle lens

[0127] Number of layers Film material Design thickness nm Plating ratio parameters Actual thickness nm 1 <![CDATA[HfO2]]> 16.35 0.882 14.42 2 <![CDATA[MgF2]]> 13.41 1.087 14.58 3 <![CDATA[HfO2]]> 55.54 0.882 48.99 4 <![CDATA[MgF2]]> 67.74 1.087 73.63

[0128] Before coating each layer of the antireflection film, the previous base film layer must be etched with a Hall ion source for 10-15 minutes, and the background vacuum must be kept below 2*10 -3 Pa, the deposition temperature is 250-320℃, and the temperature is kept constant for 10-20 minutes; when plating each MgF2 film layer, the deposition rate is controlled to be 0.4-0.6nm / s, the current is 20-30A, and the film is formed by electron gun evaporation. When plating each HfO2 film layer, the deposition rate is controlled to be 0.2-0.4nm / s, the oxygen filling amount is 15-25SCCM, the ion source anode voltage is 230-280V, and the current is 5-7A.

[0129] It should be noted that, when plating, the two surfaces (concave surfaces) of the ultra-wide-angle hemispherical lens can be plated first, such as Figure 2 As shown, the coating surface is located directly below, and the edge is supported by a metal fixture to expose the coating area. At the same time, the component rotates on its own axis ω1 under the secondary planetary disk, and rotates and revolves under the orbital rotation ω of the primary planetary disk, thereby obtaining good uniformity of the film layer and playing a certain role in ensuring the surface shape.

[0130] Then, one surface (concave surface) of the ultra-wide-angle hemispherical lens is plated, such as Figure 3 As shown, the ultra-wide-angle hemispherical lens is fixed by a metal fixture and tilted at a certain angle θ. At the same time, it rotates around its own central axis at a speed of ω2. At the same time, it rotates and revolves under the orbital rotation of the primary planetary disk ω, thereby obtaining good film uniformity. Set ω=10n / s

[0131] In order to ensure the uniformity of the film during plating, the rotation speed and tilt angle need to be adjusted according to the component size. The formula is as follows:

[0132] θ=arctan(L / H)

[0133] ω2cosθ=ω1

[0134] Substituting the size of the ultra-wide-angle hemispherical lens element into the equation, θ=arctan(15.91 / 15.725), we obtain that θ is approximately 45.3°.

[0135] Substituting ω1 and θ into the equation, ω2cos45.3°=10, we can conclude that ω2 is approximately 7n / s.

[0136] After plating is completed, the ultra-wide-angle hemispherical lens is edge-cut to obtain an optical element that can be used.

[0137] Afterwards, the optical components are tested for readiness for use. Figure 6 is a schematic diagram of the residual reflectivity at an incident angle of 0° provided by the present invention, Figure 7is a schematic diagram of the residual reflectivity at an incident angle of 30° provided by the present invention, Figure 8 It is a schematic diagram of the residual reflectivity at an incident angle of 50° provided by the present invention.

[0138] Figure 6-Figure 8 In the above example, the parameters are different except for the incident angle ( Figure 6 The incident angle is 0°, Figure 7 The incident angle is 30°. Figure 8 The incident angle is 50°), and the 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; polarization state: average; first surface: front surface. It can be seen that the single-sided residual reflectivity of the anti-reflection film needs to be less than 1.5%, the band is 353-357nm, and the incident angle is 0-50°.

[0139] Also refer to Tables 3-5. Table 3 is the transmission phase difference of light with a wavelength of 345nm-395nm at an incident angle of 0°, Table 4 is the transmission phase difference of light with a wavelength of 345nm-395nm at an incident angle of 30°, and Table 5 is the transmission phase difference of light with a wavelength of 345nm-395nm at an incident angle of 50°. It can be seen that the transmission phase difference (Phase difference, Dif) can be controlled within 1°, meeting the plating requirements.

[0140] Table 3

[0141] nm Dif nm Dif nm Dif nm Dif 345 0.0000 358 0.0000 371 0.0000 384 0.0000 346 0.0000 359 0.0000 372 0.0000 385 0.0000 347 0.0000 360 0.0000 373 0.0000 386 0.0000 348 0.0000 361 0.0000 374 0.0000 387 0.0000 349 0.0000 362 0.0000 375 0.0000 388 0.0000 350 0.0000 363 0.0000 376 0.0000 389 0.0000 351 0.0000 364 0.0000 377 0.0000 390 0.0000 352 0.0000 365 0.0000 378 0.0000 391 0.0000 353 0.0000 366 0.0000 379 0.0000 392 0.0000 354 0.0000 364 0.0000 380 0.0000 393 0.0000 355 0.0000 368 0.0000 381 0.0000 394 0.0000 356 0.0000 369 0.0000 382 0.0000 395 0.0000 357 0.0000 370 0.0000 383 0.0000

[0142] Table 4

[0143] nm Dif nm Dif nm Dif nm Dif 345 0.6477 358 0.4927 371 0.3389 384 0.1761 346 0.6354 359 0.4809 372 0.3267 385 0.1632 347 0.6233 360 0.4691 373 0.3145 386 0.1502 348 0.6112 361 0.4575 374 0.3022 387 0.1371 349 0.5992 362 0.4458 375 0.2899 388 0.1240 350 0.5872 363 0.4341 376 0.2775 389 0.1108 351 0.5753 364 0.4224 377 0.2650 390 0.0975 352 0.5635 365 0.4106 378 0.2524 391 0.0842 353 0.5516 366 0.3988 379 0.2398 392 0.0708 354 0.5398 364 0.3869 380 0.2271 393 0.0574 355 0.5280 368 0.3750 381 0.2145 394 0.0439 356 0.5163 369 0.3630 382 0.2018 395 0.0303 357 0.5045 370 0.3510 383 0.1890

[0144] Table 5

[0145]

[0146]

[0147] See also Fig. 9 , Fig. 9This is the measured coating curve provided by the present invention, each 2 lines form a group, from bottom to top are the residual reflectivity curves of S light (Senkrecht, vertical polarized light) and P light (Parallel, parallel polarized light) at 0°, 30° and 50°, where R = (RS + RP) / 2. The measured result of 0°: R = (0.085247% + 0.069602%) / 2 = 0.0774245%; the measured result of 30°: R = (0.42615% + 0.36656%) / 2 = 0.396355%; the measured result of 50°: R = (0.92210% + 0.75303%) / 2 = 0.837565%. It can be seen that the measured results meet the curve index requirements.

[0148] As shown in Table 6, the transmission phase difference of the film system was tested using an ellipsometer, and it was found that the transmission phase difference under the three conditions of 0°, 30°, and 50° can meet the index requirement of less than 1°.

[0149] Table 6

[0150] angle Through phase difference deg 0° 0.00 30° 0.54 50° 0.35

[0151] After plating the two surfaces, two groups of test pieces were used for comparison, and the surface shape data before and after plating were finally obtained as shown in Table 7. The surface shape was detected using a laser interferometer with a wavelength of 633nm. The RMS value shows that the two surfaces changed from 4.563nm to 7.603nm and 5.839nm to 5.805nm before and after plating. Overall, it meets the requirements of the drawings. The reason why the change is not large is that the concave and convex degree of the two surfaces is small, which has little effect on the uniformity of the film layer and meets the surface shape requirements.

[0152] Table 7 Comparison of surface shapes before and after coating on two surfaces

[0153] serial number Front view of coating Shape after coating 1 RMS=4.563nm RMS=7.603nm 2 RMS=5.839nm RMS=5.805nm

[0154] After the coating process on the first surface, two groups of test pieces were used for comparison. The surface shape data before and after the coating were finally obtained as shown in Table 8. The surface shape was detected using a laser interferometer with a wavelength of 633nm. Since the laser interferometer could not detect the full aperture, it could only be detected by regional splicing. The detected area was about 80%. The RMS value showed that the center area changed from 4.481nm to 5.202nm and 4.392nm to 4.303nm before and after the coating on the first surface. The RMS value showed that the edge area changed from 10.388nm to 10.893nm and 6.252nm to 7.395nm before and after the coating on the first surface. Overall, the surface shape requirements, the change amount does not exceed 5nm, which proves the effectiveness of the scheme. The uniformity of the surface shape is guaranteed to a great extent while ensuring that the film system can meet the requirements.

[0155] Table 8 Surface shape comparison before and after coating on one side

[0156]

[0157] The method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens provided in an embodiment of the present invention selects HfO2 and MgF2 as coating materials, and coats an anti-reflection film on the lens body according to the specific size and shape of the optical element and the requirements of the film system, thereby solving the problem that the anti-reflection film cannot play an anti-reflection role due to the uneven thickness at the center and edge of the lens, and taking into account the surface shape accuracy of the optical element after coating while ensuring the requirements of the spectral curve, so that the edge and center positions can meet the requirements of use. By adjusting and transforming the equipment, specific adjustments are made according to the size of the optical element, so that the uniformity of the film thickness at the center and edge positions of the ultra-wide-angle lens is kept consistent, thereby achieving a certain surface shape accuracy and optical index; secondly, the film system is designed by using two high and low refractive index materials, HfO2 and MgF2, to design the film system. While ensuring the requirements of the spectral curve, the outermost layer of the film system uses low refractive index MgF2, which can minimize the reflectivity of the entire bandwidth, while widening the bandwidth, it can still ensure a low reflectivity, and can reduce the stress of the film layer and reduce the risk of film cracking. At the same time, the film system design of the present invention can ensure that the transmission phase difference of the film system is less than 1°, which ensures the imaging quality after assembly to a certain extent.

[0158] Reference herein to "one embodiment," "embodiment," or "one or more embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. In the description provided herein, numerous specific details are described. However, it is understood that embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. 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. An ultra-wide-angle hemispherical lens anti-reflection film, characterized in that: The ultra-wide-angle hemispherical lens anti-reflection film is composed of a hafnium dioxide film layer and a magnesium fluoride film layer coated on the ultra-wide-angle hemispherical lens.

2. The ultra-wide-angle hemispherical lens antireflection film according to claim 1, characterized in that: The hafnium dioxide film layer and the magnesium fluoride film layer are, in order from near to far from the ultra-wide-angle hemispherical lens, a first hafnium dioxide film layer, a first magnesium fluoride film layer, a second hafnium dioxide film layer, and a second magnesium fluoride film layer.

3. A method for coating an antireflection film for an ultra-wide-angle hemispherical lens according to claim 1 or 2, characterized in that: include: Use the Hall ion source to etch the base film layer of the ultra-wide-angle hemispherical lens for 10-15 minutes, and keep the background vacuum degree below 2*10 -3 Pascal, deposition temperature is 250-320 degrees Celsius, constant temperature for 10-20 minutes; The ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer is plated on the surface of the ultra-wide-angle hemispherical lens.

4. The method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens according to claim 3, characterized in that: The method of coating the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer on the surface of the ultra-wide-angle hemispherical lens comprises: The edge of the ultra-wide-angle hemispherical lens is clamped by a metal fixture of a planetary fixture, so that the concave surface of the ultra-wide-angle hemispherical lens is vertically downward; the primary planetary disk of the planetary fixture is set to rotate at a first angular velocity, and the secondary planetary disk of the planetary fixture is set to rotate at a second angular velocity; the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer is plated on the concave surface; The metal fixture of the planetary fixture is used to clamp the edge of the ultra-wide-angle hemispherical lens so that the convex surface of the ultra-wide-angle hemispherical lens is vertically downward; the ultra-wide-angle hemispherical lens is adjusted according to the set inclination; the first-level planetary disk of the planetary fixture is set to rotate at a first angular velocity, and the second-level planetary disk of the planetary fixture is set to rotate at a third angular velocity; and the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer is plated on the convex surface.

5. The method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens according to claim 4, characterized in that: Before adjusting the ultra-wide-angle hemispherical lens according to the set inclination, the method further includes: Obtaining the length and outer diameter of the ultra-wide-angle hemispherical lens, and determining half of the outer diameter as the radius of the ultra-wide-angle hemispherical lens; The set inclination is obtained based on the following formula: in, is the inclination, L is the length, and H is the radius.

6. The method for coating an antireflection film for an ultra-wide-angle hemispherical lens according to claim 4, characterized in that: Before setting the secondary planetary disk of the planetary fixture to rotate at the third angular velocity, the method further comprises: The third angular velocity is obtained based on the following formula: in, is the third angular velocity, is the inclination, is the second angular velocity.

7. The method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens according to any one of claims 3 to 6, characterized in that: Before coating the ultra-wide-angle hemispherical lens with the anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer, the method further comprises: Obtaining a plating ratio parameter and a plating target corresponding to the ultra-wide-angle hemispherical lens; According to the plating target and the plating ratio parameter, determining the target plating thickness of the hafnium dioxide film layer and the target plating thickness of the magnesium fluoride film layer respectively; The method of coating the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer on the surface of the ultra-wide-angle hemispherical lens comprises: The ultra-wide-angle hemispherical lens anti-reflection film is plated on the surface of the ultra-wide-angle hemispherical lens according to the target coating thickness of the hafnium dioxide film layer and the target coating thickness of the magnesium fluoride film layer.

8. The method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens according to claim 7, characterized in that: The plating ratio parameters include a first plating ratio parameter corresponding to the hafnium dioxide film layer and a second plating ratio parameter corresponding to the magnesium fluoride film layer; The step of determining the target plating thickness of the hafnium dioxide film layer and the target plating thickness of the magnesium fluoride film layer respectively according to the plating target and the plating ratio parameter comprises: Performing simulation analysis based on the plating target to determine a simulated plating thickness of the hafnium dioxide film layer and a simulated plating thickness of the magnesium fluoride film layer; The product of the simulated plating thickness of the hafnium dioxide film layer and the first plating ratio parameter is determined as the target plating thickness of the hafnium dioxide film layer, and the product of the simulated plating thickness of the magnesium fluoride film layer and the second plating ratio parameter is determined as the target plating thickness of the magnesium fluoride film layer.

9. The method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens according to claim 8, characterized in that: The step of obtaining the plating ratio parameter comprises: Obtain a first lens and a second lens made of the same base material as the ultra-wide-angle hemispherical lens; A hafnium dioxide film layer of a first set thickness is deposited on the surface of the first lens, and a magnesium fluoride film layer of a second set thickness is deposited on the surface of the second lens, wherein the first set thickness and the second set thickness are 150-300 nanometers; Performing simulation analysis on the plated first lens to determine the simulated plated thickness of the hafnium dioxide film layer on the first lens, and performing simulation analysis on the plated second lens to determine the simulated plated thickness of the magnesium fluoride film layer on the second lens; The ratio of the first set thickness to the simulated coating thickness of the hafnium dioxide film layer on the first lens is determined as a first coating ratio parameter corresponding to the hafnium dioxide film layer, and the ratio of the second set thickness to the simulated coating thickness of the magnesium fluoride film layer on the second lens is determined as a second coating ratio parameter corresponding to the magnesium fluoride film layer.

10. The method for coating an anti-reflection film for an ultra-wide-angle hemispherical lens according to claim 3, characterized in that: The method of coating the ultra-wide-angle hemispherical lens anti-reflection film composed of a hafnium dioxide film layer and a magnesium fluoride film layer on the surface of the ultra-wide-angle hemispherical lens comprises: When plating the hafnium dioxide film layer, the deposition rate is controlled to be 0.2-0.4 nanometers per second, the oxygen filling amount is 15-25 standard cubic centimeters per minute, the ion source anode voltage is 230-280 volts, and the current is 5-7 amperes; When the magnesium fluoride film is plated, the deposition rate is controlled to be 0.4-0.6 nanometers per second, the current is 20-30 amperes, and the magnesium fluoride is formed into a film by electron gun evaporation.

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