Ultra-thin low-reflection film optical filter based on ultra-multilayer vacuum coating technology and coating process of ultra-thin low-reflection film optical filter

Abstract

The invention provides an ultra-thin low-reflection film optical filter based on a multilayer vacuum coating technology and a coating process thereof, the ultra-thin low-reflection film optical filter comprises a substrate Sub and an ultra-thin low-reflection film structure with a single face arranged on the surface of the substrate, the ultra-thin low-reflection film structure sequentially comprises the following film layers: 1H, 2M, 3H, 4M, 5H, 6M, 7H, 8M, 9H, 10M, 11H and 12L, the thickness of the film layers is accurately controlled to realize low reflection in the wave band of 420nm-680nm, the maximum reflectivity Rmax is less than or equal to 0.1%, and the maximum reflectivity Rmax is less than or equal to 0.1%. According to the invention, the problem of'ghosting 'phenomena of stray light and dazzle light caused by high reflectivity in the wave band of 420-680 nm is solved, a magnesium fluoride film layer with the refractive index lower than that of trititanium pentoxide is added between the film layer and incident medium air for film layer optimization, and the film layer has high transmittance T of about 99.9%. The admittance value of the film layer and the substrate and the admittance value of the film layer and the incident medium are matched, the adding layer is equivalent to an antireflection film at the boundary of the multilayer film, and finally the purposes of ultra-low reflection of the wave band and approaching to zero reflection are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical thin films, and in particular to an ultra-thin low-reflection film filter based on ultra-multi-layer vacuum coating technology and a coating process thereof. Background Art

[0002] It is well known in the optical arts that reflections of light from glass and other surfaces are undesirable or produce visual discomfort. In addition to this undesirable effect, reflected light can cause users to feel dizzy or produce blurred images. For optical lenses, which are of particular interest, compositions and methods have been developed for reducing reflections from optical lens surfaces. To ensure that the residual reflection remains at a relatively small value throughout the visible spectrum, the prior art has proposed a considerable number of anti-reflection (AR) coatings. Single or double layer coatings have given significant improvements, but the residual reflection is still greater than desired. To improve the properties of AR, the prior art has resorted to AR coatings having three or more layers.

[0003] Surface microstructure + nanoimprint technology is derived from photonic crystal technology. Photonic crystal templates are made using nanoimprint technology, transferred to the film, and then attached to the surface of optoelectronic components. There may be multi-level diffraction and poor wear resistance. Inclined porous coating and large-angle evaporation of porous films can produce a low refractive index of at least 1.05, which inevitably leads to wavelength drift. ALD deposition technology can be accurately controlled to produce relatively good ultra-thin low-reflection films with excellent uniformity, but may cause greater scattering, uncontrollable wear resistance, and currently low production efficiency. Ultra-multi-layer vacuum coating is easy to design, combined with ion source assistance, and has excellent physical and optical properties.

[0004] Conventional products on the market have a reflectivity of Rmax≤0.5. For optical lenses of high-end modules, light energy loss, glare, and stray light "ghosting" phenomena will occur during use. Therefore, an ultra-low reflection filter with a reflectivity of Rmax≤0.1 in the 420nm-680nm band is also required. Summary of the invention

[0005] The purpose of the present invention is to provide an ultra-thin low-reflection film filter and a coating process thereof based on ultra-multi-layer vacuum coating technology to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising a substrate Sub and an ultra-thin low-reflection film structure disposed on a single side on the surface of the substrate, wherein the substrate is made of blue glass or white glass, and the ultra-thin low-reflection film structure comprises the following film layers in sequence: 1H, 2M, 3H, 4M, 5H, 6M, 7H, 8M, 9H, 10M, 11H, 12L, wherein the numbers represent the order of the film layers, H, M, and L represent the refractive index of the film layers, H represents that the film layer adopts a high refractive index material, M represents that a medium refractive index material is adopted, and L represents that a low refractive index material is adopted, wherein the high refractive index, medium refractive index, and low refractive index materials are titanium pentoxide, silicon dioxide, and magnesium fluoride, respectively, and the optical thickness of each film layer is λ 0 / 4 , the unit of physical thickness is nm,

[0007] The optical thickness of the 1H layer is 0.167 and the physical thickness is 9.43;

[0008] The optical thickness of the 2M layer is 0.575 and the physical thickness is 53.96;

[0009] The optical thickness of the 3H layer is 0.444 and the physical thickness is 25.04;

[0010] The optical thickness of the 4M layer is 0.538 and the physical thickness is 50.51;

[0011] The optical thickness of the 5H layer is 0.382 and the physical thickness is 21.52;

[0012] The optical thickness of the 6M layer is 0.852 and the physical thickness is 80.00;

[0013] The optical thickness of the 7H layer is 0.322 and the physical thickness is 18.14;

[0014] The optical thickness of the 8M layer is 0.445 and the physical thickness is 41.79;

[0015] The optical thickness of the 9H layer is 1.312 and the physical thickness is 73.92;

[0016] The optical thickness of the 10M layer is 0.095 and the physical thickness is 8.92;

[0017] The optical thickness of the 11H layer is 0.534 and the physical thickness is 30.08;

[0018] The optical thickness of the 12L layer is 0.98 and the physical thickness is 97.34.

[0019] The refractive index of the substrate Sub is 1.52.

[0020] Through the above scheme, the optical thickness and physical thickness of the film layer are the designed thickness, the film structure of the short-wave pass filter film is Sub / (0.5LH0.5L)^11, the coating substrate Sub is k9 glass, the titanium pentoxide film layer is H, and the silicon dioxide film layer is L, so that the equivalent refractive index of the film layer in the passband is close to the refractive index of the substrate, and the ripples in the long-wave pass transmission passband area are compressed to achieve the anti-reflection and anti-transmission effect in the 420nm-680nm band, which can achieve low reflection in the 420nm-680nm band, and the maximum reflection The reflectivity Rmax≤0.1%, the maximum transmittance T is about 99.9% high transmittance requirements, the present invention solves the "ghost" phenomenon of stray light and glare caused by high reflectivity in the 420nm-680nm band, and a magnesium fluoride film layer with a refractive index lower than that of titanium pentoxide is added between the film layer and the incident medium air to optimize the film layer, so that the admittance values ​​of the film layer and the substrate and the film layer and the incident medium are matched, and the added layer is equivalent to the anti-reflection film at the boundary of the multi-layer film, and finally the ultra-low reflection in this wide band is achieved, and the purpose of near zero reflection is achieved.

[0021] A process for coating an ultra-thin low-reflection film filter based on multi-layer vacuum coating technology, characterized in that it includes the following steps:

[0022] S1: Loading titanium pentoxide film material, silicon dioxide and magnesium fluoride film material into the coating machine cavity;

[0023] S2: After the coating substrate is cleaned and dehydrated, it is placed in a coating machine. The coating machine is evacuated and heated to 200°C and then baked at a constant temperature for 30 minutes. When the vacuum degree in the coating machine is 6.0-4Pa, the ion source is started for cleaning for 10 minutes. The anode voltage of the ion source is 180V, the anode current is 5A, and the high-purity argon gas flow rate is 5SCCM;

[0024] S3: Electron beam and ion source bombardment vacuum coating process is used to sequentially coat 1H, 2M, 3H, 4M, 5H, 6M, 7H, 8M, 9H, 10M, 11H, 12L film layers on the first surface of the substrate, and the optical thickness is monitored in real time. The physical thickness is monitored according to the optical thickness monitoring result. When the set thickness is reached, a stop signal is issued, and the equipment switches the evaporation source to coat the next film layer. When the silicon dioxide film is coated, the temperature is 200°C, the vacuum degree is 2.3-2Pa, and 8KV high voltage is used. The magnetic field is focused to form an electron beam to bombard the silicon dioxide film material to evaporate the silicon dioxide film material. The evaporation rate / second, and at the same time, the ion source bombardment was turned on for ion beam assisted deposition, the ion source anode voltage was 130V, the anode current was 3A, the high-purity argon flow rate was 8SCCM, and the high-purity oxygen flow rate was 20SCCM.

[0025] When the silicon dioxide film is coated, the temperature is 200°C, the vacuum degree is 2.3-2Pa, 8KV high voltage is used, and the magnetic field is focused to form an electron beam to bombard the silicon dioxide film material to evaporate the silicon dioxide film material. The evaporation rate / second, and at the same time, the ion source bombardment was turned on for ion beam assisted deposition, the ion source anode voltage was 500V, the anode current was 500mA, the high-purity argon flow rate was 8SCCM, and the high-purity oxygen flow rate was 20SCCM.

[0026] When the titanium pentoxide film is coated, the temperature is 200°C, the vacuum degree is 2.3-2Pa, 8KV high voltage is used, and the magnetic field is focused to form an electron beam to bombard the titanium pentoxide film material to evaporate the titanium pentoxide film material. The evaporation rate is / second, and at the same time, the ion source bombardment was turned on for ion beam assisted deposition, the ion source anode voltage was 130V, the anode current was 3A, the high-purity argon flow rate was 8SCCM, and the high-purity oxygen flow rate was 20SCCM.

[0027] When the magnesium fluoride film is coated, the temperature is 300°C, 8KV high voltage is used, and a magnetic field is used to focus to form an electron beam to bombard the magnesium fluoride film material to evaporate the magnesium fluoride film material. The evaporation rate / Second.

[0028] The coating machine includes a direct light control system, which includes a light source system, a light receiving system, a collection system and a control system. The light source system includes a bulb, a bulb box, a bulb holder and a bulb power supply. The bulb is installed and fixed in the bulb holder. The bulb power supply outputs a voltage. The bulb emits light in the 360-2500nm band after being powered on. The light receiving system includes an adapter plate, a collimator and an optical fiber. The collimator is fixed to the outside of the coating machine through an adapter plate. One end of the optical fiber is vertically fixed on the collimator. The collimator is equipped with an XYZ-axis moving device. The collection system includes a monochromator, a photodiode, a signal amplifier and a collection module.

[0029] Through the above scheme, based on the interference effect of light, during the coating process, the thickness of the film changes continuously, and at the same time, its transmittance also changes continuously. When the film thickness reaches the control wavelength λ / 4 or its integer multiple, its reflected light or transmitted light will reach a maximum (minimum) value. By monitoring this maximum (minimum) value as a scale, the optical thickness of the film on the surface of the part can be directly measured and controlled. The optical fiber is connected with the optical fiber receiving head and the monitoring product. The light emitted by the bulb is on the same normal line to ensure that the received light intensity is maximum. The received light is input into the monochromator through the optical fiber. The monochromator sets the monitoring wavelength according to the software, and chops and outputs a single wavelength light of the set wavelength. The output light passes through the photoelectric diode, and the light intensity signal is converted into an extremely weak electrical signal. This electrical signal is transmitted through the signal line The light is input into the signal amplifier, linearly amplified into an electrical signal that can be collected, and then enters the collection module for A / D conversion. The analog current signal is converted into a digital signal and transmitted to the host computer through the USB protocol. The control system includes a matching software algorithm. The software algorithm calculates the transmittance (%) of the monitored product in real time according to the measured light intensity signal and records it. The optical thickness of the monitored product at this time is calculated by monitoring the change in transmittance (mainly based on the maximum / minimum value) and compared with the set thickness. When the set thickness is reached, a stop signal is issued, the equipment turns off the evaporation source, stops the accumulation of the film layer, and controls the optical thickness of the film layer on the surface of the part. The control of the film layer has a high precision and can greatly improve the coating yield of the film layer.

[0030] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0031] 1. In the 420nm-680nm band, the reflectivity Rmax≤0.1, reaching the optical parameters of ultra-low reflection, which can effectively control the "ghost" phenomenon of astigmatism and glare. The magnesium fluoride film layer is further optimized to achieve a near-zero reflection effect, which can meet the needs of high-end optical modules on the market.

[0032] 2. The optical control system is used to directly monitor the optical thickness and thus control the physical thickness. The static signal accuracy is ±0.02%. The optical control system realizes the compensation function and the stop point correction function through the software algorithm to further control the coating accuracy. The whole process of film coating is monitored and corrected to ensure the quality of the final filter product. The yield rate is greatly improved, which is suitable for industrial large-scale production.

[0033] 3. The film structure has only 12 layers, the overall number of film layers is low, the coating time is also short, and it has excellent optical parameters and good energy-saving and emission reduction effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0035] Figure 1 is a schematic diagram of a broadband anti-reflection film on a substrate surface;

[0036] Figure 2 It is a schematic diagram of the design parameter reflectivity;

[0037] Figure 3 It is a schematic diagram of the change of luminous flux of design parameters;

[0038] Figure 4 is an AR reflection characterization diagram of Example 1-5;

[0039] Figure 5 is the AR reflection characterization diagram of Example 6-10;

[0040] Figure 6 It is a schematic diagram of the light control system structure. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The present invention provides a technical solution: comprising a substrate Sub and an ultra-thin low-reflection film structure disposed on a single side of the substrate surface, wherein the substrate material is blue glass or white glass, and the ultra-thin low-reflection film structure sequentially comprises the following film layers: 1H, 2M, 3H, 4M, 5H, 6M, 7H, 8M, 9H, 10M, 11H, 12L, wherein the numbers represent the order of the film layers, H, M, and L represent the refractive index of the film layers, H represents that the film layer adopts a high refractive index material, M represents that a medium refractive index material is adopted, and L represents that a low refractive index material is adopted, and the high refractive index, medium refractive index, and low refractive index materials are titanium pentoxide, silicon dioxide, and magnesium fluoride, respectively, and the optical thickness of each film layer is λ0 / 4, and the physical thickness unit is nm,

[0043] The optical thickness of the 1H layer is 0.167 and the physical thickness is 9.43;

[0044] The optical thickness of the 2M layer is 0.575 and the physical thickness is 53.96;

[0045] The optical thickness of the 3H layer is 0.444 and the physical thickness is 25.04;

[0046] The optical thickness of the 4M layer is 0.538 and the physical thickness is 50.51;

[0047] The optical thickness of the 5H layer is 0.382 and the physical thickness is 21.52;

[0048] The optical thickness of the 6M layer is 0.852 and the physical thickness is 80.00;

[0049] The optical thickness of the 7H layer is 0.322 and the physical thickness is 18.14;

[0050] The optical thickness of the 8M layer is 0.445 and the physical thickness is 41.79;

[0051] The optical thickness of the 9H layer is 1.312 and the physical thickness is 73.92;

[0052] The optical thickness of the 10M layer is 0.095 and the physical thickness is 8.92;

[0053] The optical thickness of the 11H layer is 0.534 and the physical thickness is 30.08;

[0054] The optical thickness of the 12L layer is 0.98 and the physical thickness is 97.34.

[0055] The refractive index of the substrate Sub is 1.52.

[0056] The plating process includes the following steps:

[0057] S1: Loading titanium pentoxide film material, silicon dioxide and magnesium fluoride film material into the coating machine cavity;

[0058] S2: After the coating substrate is cleaned and dehydrated, it is placed in the coating machine. The coating machine is evacuated and heated to 200°C and then baked at a constant temperature for 30 minutes. When the vacuum degree in the coating machine is 6.0-4Pa, the ion source is started for cleaning for 10 minutes. The ion source anode voltage is 180V, the anode current is 5A, and the high-purity argon gas flow rate is 5SCCM;

[0059] S3: Electron beam and ion source bombardment vacuum coating process is used to sequentially coat 1H, 2M, 3H, 4M, 5H, 6M, 7H, 8M, 9H, 10M, 11H, 12L film layers on the first surface of the substrate, and the optical thickness is monitored in real time. The physical thickness is monitored according to the optical thickness monitoring result. When the set thickness is reached, a stop signal is issued, and the equipment switches the evaporation source to coat the next film layer. When the silicon dioxide film is coated, the temperature is 200°C, the vacuum degree is 2.3-2Pa, and 8KV high voltage is used. The magnetic field is focused to form an electron beam to bombard the silicon dioxide film material to evaporate the silicon dioxide film material. The evaporation rate / second, and at the same time, the ion source bombardment was turned on for ion beam assisted deposition, the ion source anode voltage was 130V, the anode current was 3A, the high-purity argon flow rate was 8SCCM, and the high-purity oxygen flow rate was 20SCCM.

[0060] When the silicon dioxide film is coated, the temperature is 200℃, the vacuum degree is 2.3-2Pa, and 8KV high voltage is used. The magnetic field is focused to form an electron beam to bombard the silicon dioxide film material, causing the silicon dioxide film material to evaporate. The evaporation rate / second, and at the same time, the ion source bombardment was turned on for ion beam assisted deposition, the ion source anode voltage was 500V, the anode current was 500mA, the high-purity argon flow rate was 8SCCM, and the high-purity oxygen flow rate was 20SCCM.

[0061] When the titanium pentoxide film is coated, the temperature is 200℃, the vacuum degree is 2.3-2Pa, and 8KV high voltage is used. The magnetic field is focused to form an electron beam to bombard the titanium pentoxide film material, causing the titanium pentoxide film material to evaporate. The evaporation rate is / second, and at the same time, the ion source bombardment was turned on for ion beam assisted deposition, the ion source anode voltage was 130V, the anode current was 3A, the high-purity argon flow rate was 8SCCM, and the high-purity oxygen flow rate was 20SCCM.

[0062] When the magnesium fluoride film is coated, the temperature is 300℃, 8KV high voltage is used, and the magnetic field is focused to form an electron beam to bombard the magnesium fluoride film material, causing the magnesium fluoride film material to evaporate. The evaporation rate is / Second.

[0063] The coating machine includes a direct light control system, which includes a light source system, a light receiving system, a collection system and a control system. The light source system includes a bulb, a bulb box, a bulb holder and a bulb power supply. The bulb is installed and fixed in the bulb holder. The bulb power supply outputs voltage. When the bulb is powered on, it emits light in the 360-2500nm band. The light receiving system includes an adapter plate, a collimator and an optical fiber. The collimator is fixed to the outside of the coating machine through an adapter plate. One end of the optical fiber is vertically fixed on the collimator. The collimator is equipped with an XYZ-axis moving device. The collection system includes a monochromator, a photodiode, a signal amplifier and an acquisition module.

[0064] The filter was coated with a film layer by using a Palette Aluga1550 coating machine with set design parameters. After coating, the coating data was recorded. Then, the reflectivity of the filter in Examples 1-10 was tested using an Agilent Cary7000 spectrometer. The wavelength unit in the following table is nm, and the reflectivity unit is %. The test results are as follows: Examples 1-5

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072] Embodiment 6-10

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080] According to the example table and Figure 4 Figure 5 It can be seen that the low reflection in the 420nm-680nm band has a maximum reflectivity of less than 0.1%, which is extremely low and can meet the requirements of most high-end optical modules on the market. Among them, the best effects are Example 4 and Example 5, which can achieve the requirement of maximum reflectivity less than 0.1% in the 411nm-688nm band.

[0081] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0082] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An ultra-thin low-reflection film filter based on multi-layer vacuum coating technology, characterized in that: It includes a substrate Sub and an ultra-thin low-reflection film structure disposed on a single surface of the substrate, wherein the substrate is made of blue glass or white glass, and the ultra-thin low-reflection film structure includes the following film layers in sequence: 1H, 2M, 3H, 4M, 5H, 6M, 7H, 8M, 9H, 10M, 11H, 12L, wherein the numbers represent the order of the film layers, H, M, and L represent the refractive index of the film layers, H represents that the film layer adopts a high refractive index material, M represents that the film layer adopts a medium refractive index material, and L represents that the film layer adopts a low refractive index material. The high refractive index, medium refractive index, and low refractive index materials are titanium pentoxide, silicon dioxide, and magnesium fluoride, respectively, and the optical thickness of each film layer is λ 0 / 4 , the unit of physical thickness is nm, The optical thickness of the 1H layer is 0.167 and the physical thickness is 9.43; The optical thickness of the 2M layer is 0.575 and the physical thickness is 53.96; The optical thickness of the 3H layer is 0.444 and the physical thickness is 25.04; The optical thickness of the 4M layer is 0.538 and the physical thickness is 50.51; The optical thickness of the 5H layer is 0.382 and the physical thickness is 21.52; The optical thickness of the 6M layer is 0.852 and the physical thickness is 80.00; The optical thickness of the 7H layer is 0.322 and the physical thickness is 18.14; The optical thickness of the 8M layer is 0.445 and the physical thickness is 41.79; The optical thickness of the 9H layer is 1.312 and the physical thickness is 73.92; The optical thickness of the 10M layer is 0.095 and the physical thickness is 8.92; The optical thickness of the 11H layer is 0.534 and the physical thickness is 30.08; The optical thickness of the 12L layer is 0.98 and the physical thickness is 97.

34.

2. The ultra-thin low-reflection film filter based on multi-layer vacuum coating technology according to claim 1, characterized in that: The refractive index of the substrate Sub is 1.

52.

3. A process for coating an ultra-thin low-reflection film filter based on multi-layer vacuum coating technology according to any one of claims 1-2, characterized in that: The following steps are involved: S1: Loading titanium pentoxide film material, silicon dioxide and magnesium fluoride film material into the coating machine cavity; S2: After the coating substrate is cleaned and dehydrated, it is placed in a coating machine. The coating machine is evacuated and heated to 200°C and then baked at a constant temperature for 30 minutes. When the vacuum degree in the coating machine is 6.0-4Pa, the ion source is started for cleaning for 10 minutes. The anode voltage of the ion source is 180V, the anode current is 5A, and the high-purity argon gas flow rate is 5SCCM; S3: Use electron beam and ion source bombardment vacuum coating process to coat 1H, 2M, 3H, 4M, 5H, 6M, 7H, 8M, 9H, 10M, 11H, 12L film layers on the first surface of the substrate in sequence, monitor the optical thickness in real time, monitor the physical thickness based on the optical thickness monitoring result, and when the set thickness is reached, a stop signal is issued, the equipment switches the evaporation source, and proceeds to coat the next film layer.

4. The ultra-thin low-reflection film filter based on super-multi-layer vacuum coating technology according to claim 3, characterized in that: When the silicon dioxide film is coated, the temperature is 200°C, the vacuum degree is 2.3-2Pa, 8KV high voltage is used, and the magnetic field is focused to form an electron beam to bombard the silicon dioxide film material to evaporate the silicon dioxide film material. The evaporation rate / second, and at the same time, the ion source bombardment was turned on for ion beam assisted deposition, the ion source anode voltage was 500V, the anode current was 500mA, the high-purity argon flow rate was 8SCCM, and the high-purity oxygen flow rate was 20SCCM.

5. The ultra-thin low-reflection film filter based on super-multi-layer vacuum coating technology according to claim 3, characterized in that: When the titanium pentoxide film is coated, the temperature is 200°C, the vacuum degree is 2.3-2Pa, 8KV high voltage is used, and the magnetic field is focused to form an electron beam to bombard the titanium pentoxide film material to evaporate the titanium pentoxide film material. The evaporation rate is / second, and at the same time, the ion source bombardment is turned on for ion beam assisted deposition, the ion source anode voltage is 130V, the anode current is 3A, the high-purity argon flow rate is 8SCCM, and the high-purity oxygen flow rate is 20SCCM.

6. The ultra-thin low-reflection film filter based on super-multi-layer vacuum coating technology according to claim 3, characterized in that: When the magnesium fluoride film is coated, the temperature is 300°C, 8KV high voltage is used, and a magnetic field is used to focus to form an electron beam to bombard the magnesium fluoride film material to evaporate the magnesium fluoride film material. The evaporation rate / Second.

7. The ultra-thin low-reflection film filter based on super-multi-layer vacuum coating technology according to claims 3-6, characterized in that: The coating machine includes a direct light control system, which includes a light source system, a light receiving system, a collection system and a control system. The light source system includes a bulb, a bulb box, a bulb holder and a bulb power supply. The bulb is installed and fixed in the bulb holder. The bulb power supply outputs a voltage. The bulb emits light in the 360-2500nm band after being powered on. The light receiving system includes an adapter plate, a collimator and an optical fiber. The collimator is fixed to the outside of the coating machine through an adapter plate. One end of the optical fiber is vertically fixed on the collimator. The collimator is equipped with an XYZ-axis moving device. The collection system includes a monochromator, a photodiode, a signal amplifier and a collection module.

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