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The difference between vacuum coating and optical coating



Vacuum coating mainly uses glow discharge to impact argon (Với) các ion trên bề mặt của mục tiêu.
The atoms of the target material are ejected and accumulate on the surface of the substrate to form a thin film.The properties and uniformity of the sputtered film are better than those of the vaporized film, but the coating speed is much slower than that of the vaporized film..Almost all new sputtering equipment use powerful magnets to spiral electrons to accelerate the ionization of argon around the target.
Causes the collision probability between the target and the argon ions to increase,
Increase sputtering rate.Generally, lớp phủ kim loại chủ yếu sử dụng phún xạ DC, và vật liệu gốm không dẫn điện sử dụng phún xạ RF AC. The basic principle is to use glow discharge (glow discharge in vacuum).
discharge) The argon (Với) ions hit the target surface, and the cations in the plasma will accelerate to the negative electrode surface as the sputtered material. This impact will cause the target material to fly out and deposit on the substrate Film on.Generally speaking, việc sử dụng quá trình phún xạ cho lớp phủ phim có một số đặc điểm: (1) Kim khí, hợp kim hoặc chất cách điện có thể được làm thành vật liệu phim.(2) Trong điều kiện thiết lập thích hợp, một màng mỏng có cùng thành phần có thể được tạo ra từ nhiều mục tiêu phức tạp.(3) Bằng cách bổ sung oxy hoặc các khí hoạt động khác trong khí quyển xả, một hỗn hợp hoặc hợp chất của vật liệu đích và các phân tử khí có thể được tạo ra.(4) Dòng đầu vào mục tiêu và thời gian phún xạ có thể được kiểm soát, và dễ dàng có được độ dày màng có độ chính xác cao.(5) So với các quy trình khác, nó có lợi hơn cho việc sản xuất các màng đồng nhất có diện tích lớn.(6) Các hạt phún xạ hầu như không bị ảnh hưởng bởi trọng lực, and the positions of the target and the substrate can be freely arranged.(7) Độ bền kết dính giữa chất nền và màng nhiều hơn 10 lần so với màng lắng đọng hơi nói chung, và bởi vì các hạt văng ra mang năng lượng cao, chúng sẽ tiếp tục khuếch tán trên bề mặt tạo màng để thu được màng cứng và đặc. Đồng thời, the high energy makes the substrate only need Crystallized film can be obtained at lower temperature.(8) Mật độ tạo mầm cao ở giai đoạn đầu của quá trình hình thành màng, which can produce ultra-thin continuous film below 10nm.(9) The target material has a long life and can be automatically and continuously produced for a long time.(10) Vật liệu mục tiêu có thể được tạo thành nhiều hình dạng khác nhau, with the special design of the machine for better control and the most efficient production.

Lớp phủ quang học
1. Wear-resistant film (dura film)
Regardless of whether it is made of inorganic or organic materials, in daily use, friction with dust or grit (ôxít silic) will cause the lens to wear and scratches on the surface of the lens..Compared with glass sheet,
The hardness of organic materials is relatively low, and it is more prone to scratches.Through the microscope, we can observe that the scratches on the lens surface are mainly divided into two types. One is the scratches caused by grit, which is shallow and small, which is not easy for the wearer to detect; the other is the scratches caused by the larger grit. , Deep and rough around, being in the central area will affect vision.
(1) Technical characteristics
1) The first generation of anti-wear film technology
The anti-wear film began in the early 1970s. At that time, it was believed that glass lenses were not easy to grind because of their high hardness, while organic lenses were too soft and were easy to wear..Therefore, the quartz material is plated on the surface of the organic lens under vacuum conditions to form a very hard wear-resistant film. Tuy nhiên, due to the mismatch between its thermal expansion coefficient and the base material, it is easy to peel off and the film is brittle, so it is resistant to Unsatisfactory wear effect.
2) The second generation of anti-wear film technology
After the 1980s, researchers have theoretically found that the mechanism of wear is not only related to hardness. The film material has the dual characteristics ofhardness/deformation”, đó là, some materials have higher hardness but less deformation, and some Material hardness is low, but deformation is large.The second generation of anti-wear film technology is to plate a material with high hardness and not easy to crack on the surface of the organic lens through the immersion process..
3) The third generation of anti-wear film technology
The third-generation anti-wear film technology was developed after the 1990s, mainly to solve the problem of wear resistance after the organic lens is coated with an anti-reflection film..Since the hardness of the organic lens base and the hardness of the anti-reflective coating are quite different, the new theory believes that there needs to be an anti-wear coating between the two, so that the lens can act as a buffer when it is rubbed by grit. Not prone to scratches.The hardness of the third-generation anti-wear film material is between the hardness of the anti-reflection film and the lens base, and its friction coefficient is low and it is not easy to be brittle.
4) The fourth generation of anti-wear film technology
The fourth-generation anti-film technology uses silicon atoms. Ví dụ, French Essilor’s TITUS hardening fluid contains both organic matrix and inorganic ultrafine particles including silicon to make the anti-wear film Improved hardness while having toughness.The most important modern anti-wear coating technology is the immersion method, đó là, the lens is immersed in a hardening liquid after multiple cleanings, and then lifted at a certain speed after a certain period of time..This speed is related to the viscosity of the hardening fluid and plays a decisive role in the thickness of the anti-wear film..After lifting, polymerize in an oven at about 100 °C for 4-5 giờ, and the thickness of the coating is about 3-5 microns.
(2) Test method
The most fundamental way to judge and test the wear resistance of the anti-wear film is to use it clinically, let the wearer wear the lens for a period of time, and then observe and compare the wear of the lens with a microscope.Of course, this is usually the method used before the formal promotion of this new technology. Hiện tại, the quicker and more intuitive test methods we commonly use are:
1) Frosting test
Place the lens in a promotional material filled with gravel (the grain size and hardness of the gravel are specified), and rub back and forth under certain control.After the end, use a haze meter to test the amount of diffuse reflection of the lens before and after friction, and compare it with the standard lens.
2) Steel wool test
Use a specified steel wool to rub the surface of the lens for a number of times under a certain pressure and speed, and then use a haze meter to test the amount of diffuse reflection of the lens before and after the friction, and compare it with the standard lens.Of course, we can also do it manually, rub the two lenses the same number of times with the same pressure, and then observe and compare with the naked eye..
The results of the above two test methods are relatively close to the clinical results of long-term wear by the wearer.
3) The relationship between anti-reflection film and anti-wear film
The anti-reflection coating on the surface of the lens is a very thin inorganic metal oxide material (thickness less than 1 micrômet), hard and brittle.When it is plated on a glass lens, since the base is relatively hard and the grit is scratched on it, the film layer is relatively difficult to scratch; but when the anti-reflection film is plated on the organic lens, because the base is soft, the grit is on the film. Scratched on the layer, the film is easily scratched.
Vì vậy, the organic lens must be coated with anti-wear coating before anti-reflection coating, and the hardness of the two coatings must match..
2. Anti-reflection film
(1) Why do we need anti-reflective coating?
1) Specular reflection
When light passes through the front and back surfaces of the lens, not only will it be refracted, but it will also be reflected..This kind of reflected light generated on the front surface of the lens will cause others to see the eyes of the wearer, but they will see a white light on the surface of the lens..When taking pictures, this kind of reflection will also seriously affect the appearance of the wearer.
2) “Ghost
The optical theory of spectacles believes that the refractive power of the spectacle lens will make the viewed object form a clear image at the far point of the wearer. It can also be explained as the light of the viewed object deflects through the lens and gathers on the retina to form an image point..However, because the curvature of the front and rear surfaces of the refractive lens is different, and there is a certain amount of reflected light, there will be internal reflection light between them..The internally reflected light will produce a virtual image near the far-point spherical surface, đó là, a virtual image point near the image point of the retina.These virtual image points will affect the clarity and comfort of the vision.
3) Glare
Like all optical systems, the eye is not perfect. The image formed on the retina is not a point, but a fuzzy circle..Therefore, the feeling of two adjacent points is produced by two juxtaposed more or less overlapping fuzzy circles.As long as the distance between the two points is large enough, the image on the retina will produce the sensation of two points, but if the two points are too close, the two fuzzy circles will tend to overlap and be mistaken for one point.
Contrast can be used to reflect this phenomenon and express the clarity of vision.The contrast value must be greater than a certain value (perception threshold, equivalent to 1-2) to ensure that the eyes can distinguish two adjacent points.
The calculation formula of contrast is: D=(ab)/(a+b)
Where C is the contrast, the highest value of the sensation imaged by two adjacent object points on the retina is a, and the lowest value of the adjacent part is b.The higher the contrast C value, the higher the resolution of the visual system to the two points and the clearer the perception; if the two object points are very close, the lowest value of their adjacent parts is closer to the highest value, then the C value is low , Indicating that the visual system is not clear about the two points, or can’t distinguish clearly.
Let us simulate such a scene: at night, a driver with glasses clearly sees two bicycles riding towards his car in the opposite distance..At this time, the headlights of the trailing car reflect on the rear surface of the driver’s lens: the image formed by the reflected light on the retina increases the intensity of the two observed points (bicycle lights).Vì vậy, the length of the a and b segments increases, even if the denominator (a+b) tăng, but the numerator (ab) remains the same, which causes a decrease in the value of C.The result of the reduced contrast will cause the driver’s initial feeling of the presence of two cyclists to recombine into a single image, just like the angle of distinguishing them is suddenly reduced.!
4) Throughput
The percentage of reflected light in incident light depends on the refractive index of the lens material, which can be calculated by the formula of the amount of reflection.
Reflectance formula: R=(n-1) square/(n+1) Quảng trường
NS: single-sided reflection of the lens n: refractive index of the lens material
Ví dụ, the refractive index of ordinary resin materials is 1.50, reflected light R = (1.50-1) square/(1.50 + 1) Square = 0.04=4%.
The lens has two surfaces. If R1 is the amount of the front surface of the lens and R2 is the amount of reflection on the back surface of the lens, then the total amount of reflection of the lens is R=R1+R2.(When calculating the reflection of R2, the incident light is 100%-R1).The transmittance of the lens T=100%-R1-R2.
It can be seen that if the high refractive index lens has no anti-reflection coating, the reflected light will bring more discomfort to the wearer..
(2) Nguyên tắc
Anti-reflection coating is based on light wave and interference phenomenon.If two light waves with the same amplitude and wavelength are superimposed, the amplitude of the light wave will increase; if the two light waves are of the same origin, the wave lengths are different, and if the two light waves are superimposed, they cancel each other out..The anti-reflection film uses this principle to coat the surface of the lens with an anti-reflection film, so that the reflected light generated on the front and back surfaces of the film interferes with each other, thereby canceling the reflected light and achieving the effect of anti-reflection..
1) Amplitude conditions
The refractive index of the film material must be equal to the square root of the refractive index of the lens base material.
2) Phase conditions
The thickness of the film should be 1/4 wavelength of the reference light.When d=λ/4 λ=555nm, d=555/4=139nm
For the anti-reflection coating, many spectacle lens manufacturers use light waves (wavelength of 555nm) that are more sensitive to the human eye.When the thickness of the coating is too thin (<139nm), the reflected light will appear light brownish yellow, if it is blue, it means that the thickness of the coating is too thick (>139nm).
The purpose of the coating reflective layer is to reduce the reflection of light, but it is impossible to achieve no reflection of light.There will always be residual color on the surface of the lens, but which is the best residual color, Trên thực tế, there is no standard. Hiện tại, it is mainly based on personal preference for color, and most of it is green..
We will also find that the different curvatures of the residual color on the convex and concave surfaces of the lens also make the coating speed different, so the central part of the lens is green, and the edge part is lavender or other colors..
3) Anti-reflection coating technology
Organic lens coating is more difficult than glass lens.The glass material can withstand high temperatures above 300 ° C, while the organic lens will turn yellow when it exceeds 100 °C and then quickly decompose.
Magie florua (MgF2) is usually used as the anti-reflection coating material for glass lenses. Tuy nhiên, the coating process of magnesium fluoride must be carried out at a temperature higher than 200°C, otherwise it cannot be attached to the surface of the lens, so organic lenses Don’t use it.
Kể từ những năm 1990, with the development of vacuum coating technology, the use of ion beam bombardment technology has made the combination of the film and the lens, and the combination of the film has been improved..Moreover, the refined high-purity metal oxide materials such as titanium oxide and zirconium oxide can be plated on the surface of the resin lens through the evaporation process to achieve a good anti-reflection effect..
The following is an introduction to the anti-reflective coating technology of organic lenses.
1) Preparation before coating
The lens must be pre-cleaned before receiving the coating. The cleaning requirement is very high, reaching the molecular level..Put a variety of cleaning fluids in the cleaning tank, and use ultrasonic to enhance the cleaning effect. After the lens is cleaned, put it in the vacuum chamber. During this process, pay special attention to avoiding dust and garbage in the air from sticking to the surface of the lens..The final cleaning is in the vacuum chamber. During this process, special care should be taken to avoid dust and garbage in the air from sticking to the surface of the lens..The final cleaning is performed before plating in the vacuum chamber. The ion gun placed in the vacuum chamber will bombard the surface of the lens (Ví dụ, with argon ions). After this cleaning process is completed, the coating of the anti-reflection film will be carried out..
2) Lớp phủ chân không
The vacuum evaporation process can ensure that the pure coating material is plated on the surface of the lens, và cùng một lúc, the chemical composition of the coating material can be strictly controlled during the evaporation process..The vacuum evaporation process can accurately control the thickness of the film layer, and the accuracy is up to.
3) Film firmness
For spectacle lenses, the firmness of the film is very important, and it is an important quality indicator of the lens.The quality indicators of the lens include lens anti-wear, anti-cultural museum, anti-temperature difference, vv..Vì vậy, there are many targeted physical and chemical test methods. Under the conditions of simulating the use of the wearer, the film fastness quality of the coated lens is tested..These test methods include: salt water test, steam test, deionized water test, steel wool friction test, dissolution test, adhesion test, temperature difference test and humidity test, Vân vân..
3. Anti-fouling film (top film)
(1) Nguyên tắc
After the surface of the lens is coated with multi-layer anti-reflection film, the lens is particularly prone to stains, and the stains will destroy the anti-reflection effect of the anti-reflection film.Under the microscope, we can find that the anti-reflective coating has a porous structure, so oil stains are particularly easy to penetrate into the anti-reflective coating.The solution is to coat the top film with oil and water resistance on the anti-reflective film layer, and this film must be very thin so that it will not change the optical performance of the anti-reflective film.
(2) Tiến trình
The antifouling film material is mainly fluoride, and there are two processing methods, one is immersion method, the other is vacuum coating, and the most common method is vacuum coating.The most commonly used method is vacuum coating.After the anti-reflective coating is completed, the fluoride can be plated on the reflective film using an evaporation process.The anti-fouling film can cover the porous anti-reflection film layer, and can reduce the contact area of water and oil with the lens, so that the oil and water droplets are not easy to adhere to the surface of the lens, so it is also called waterproof film.
For organic lenses, the ideal surface system treatment should be a composite film including anti-wear film, multilayer anti-reflection film and top film anti-fouling film.Usually the anti-wear film coating is the thickest, about 3-5mm, and the thickness of the multilayer anti-reflection film is about 0.3um, the thinnest anti-fouling wax coating on the top layer, about 0.005-0.01mm.Take the French Essilor Crizal, composite film as an example, the lens base is first coated with a wear-resistant film with organic silicon; then using IPC technology, the anti-reflection film is plated by ion bombardment Pre-cleaning before cleaning; after cleaning, use high-hardness zirconium dioxide (ZrO2) and other materials for vacuum coating of multilayer anti-reflection coatings; cuối cùng, plate the top film with a contact angle of 110.The successful development of the diamond crystal composite film technology shows that the surface treatment technology of the organic lens has reached a new level.

If it is only for the film thickness test, the difference between vacuum coating and optical coating is:
1. Lớp phủ chân không: Generally TiN, CrN, TiC, ZrN, the thickness of electroplating is about 3~5 microns.In general, the thickness of the vacuum coating film cannot be tested on the equipment;
2. The film thickness test of the optical coating can be installed on the top of the coating machine with a film thickness tester..
The earliest is the light control test, and now the crystal control (dao động tinh thể) is generally used to test the thickness of the coating using the frequency of the crystal oscillator..Different film thicknesses are different.
Even if the coating machine is made in China, the film thickness tester is also made in the United States or South Korea..The model of GM USA is: MDC360C.

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