"Vacuum Technology" Hidden in the Camera

These coating layers, which are 10,000 times thinner than a hair, can accurately control the trajectory of light: anti-reflection film eliminates glare interference, anti-reflection film improves light efficiency, and oleophobic film resists fingerprint invasion.

 

 

1. Why do mobile phone lenses need coating?

    The core purpose of mobile phone lens coating is to reduce light reflection and increase light transmittance. When light passes through the lens, part of the light will be reflected by the surface of the lens (about 5%~10%), resulting in gray imaging, glare or color distortion. By coating the surface of the lens with a nano-scale film and utilizing the principle of light interference, the reflectivity can be significantly reduced. For example, a single-layer coating can reduce some reflections, while high-end mobile phones (such as the iPhone) use multi-layer anti-reflective coatings with a transmittance of up to 99.5%, making the picture purer and the colors more realistic. Simply put, coating is like putting a pair of "contact lenses" on the lens, allowing light to enter the sensor more efficiently instead of being wasted on reflections.

 

2. How does coating affect your photography experience?

 

Different types of coatings have a direct impact on mobile phone photography:

Anti-reflection coating:

    This is the most common type of coating. When light hits the lens, part of it will be reflected, which will result in a loss of a lot of light, and the resulting photos will be dark. The function of the anti-reflection coating is to reduce the reflection of light and allow more light to enter the lens. For example, coating a layer of magnesium fluoride film on the surface of the lens can greatly reduce the reflectivity of light. In this way, the transmittance of the lens is improved, and the photos taken will be brighter and clearer.

Anti-reflection film:

    In contrast to anti-reflection film, anti-reflection film increases light reflection. It is used in some special application scenarios, such as some reflectors in optical instruments. By coating them with anti-reflection film, the intensity of reflected light can be enhanced and the optical efficiency of the instrument can be improved. However, anti-reflection film is generally not commonly used on mobile phone lenses.

Waterproof and oil-proof membrane:

    Nowadays, mobile phones are often accidentally stained with water or oil, which has a significant impact on the lens. Waterproof and oil-proof film can solve this problem. It prevents water and oil from adhering to the surface of the lens. Once water droplets or oil fall on the lens, they will form water droplets or oil droplets and roll down without affecting the shooting effect. This coating is very practical in daily life and can keep our mobile phone lenses clean at all times.

Infrared cut-off film:

    The infrared cut-off film uses precise nano-coating technology to specifically intercept infrared light that is invisible to the human eye. If these infrared rays enter the image sensor, they will cause distortion such as color cast and fogging in the photos. Our coating process can accurately filter infrared light waves above 780nm while ensuring the perfect passage of visible light, improving color reproduction by up to 30%.

 

3.Coating process

 

Physical Vapor Deposition (PVD):

    This is a very important coating process. It is a process that uses physical methods to turn the coating material into a gaseous state under a vacuum environment, and then deposits it on the surface of the lens to form a thin film. Common physical vapor deposition methods include evaporation coating and sputtering coating.

    Evaporation coating is to heat the coating material to the evaporation temperature, turn it into gaseous atoms or molecules, and then deposit it on the surface of the lens. This method is relatively simple and the cost is relatively low, but the uniformity of the coating may not be very good.

    Sputtering coating is to bombard the coating material target with high-energy particles, so that the target atoms are sputtered to the surface of the lens to form a thin film. The advantages of sputtering coating are good coating uniformity, strong film adhesion, and the ability to coat various complex film structures. Many high-end mobile phone lenses are now coated with sputtering coating technology.

Chemical Vapor Deposition（CVD）：

    Chemical vapor deposition uses gaseous precursors to react chemically on the lens surface to form a solid film. This method can be used to deposit films at lower temperatures, causing less damage to the lens. In addition, the composition and thickness of the film can be precisely controlled by controlling the reaction conditions. However, chemical vapor deposition equipment is relatively complex and expensive.

Sol-gel method：

    The sol-gel method is to make the coating material into a sol, and then evenly coat it on the lens surface. After drying and heat treatment, the sol becomes a gel and finally forms a thin film. The advantages of this method are simple coating equipment, low cost, and it can coat a large area of ​​the lens surface. However, it is relatively difficult to control the coating thickness, and the quality of the film layer may not be as good as that of physical vapor deposition and chemical vapor deposition methods.

 

4.Number and thickness of coating layers：

 

Number of layers：

    Generally speaking, the coating of mobile phone lenses is not a single layer, but a multi-layer one. Multi-layer coating can combine the advantages of various coatings to further improve the optical performance of the lens. For example, it is common to add other functional film layers such as waterproof and oil-proof film on the basis of anti-reflection film. The number of layers can range from a few layers to more than ten layers. The more layers there are, the more obvious the performance improvement of the lens, but the coating process will also be more complicated.

Thickness：

    The thickness of the coating is also critical. Different types of coatings have different thickness requirements. Generally speaking, the thickness of the anti-reflection film is about a few hundred nanometers. This thickness is designed based on the principle of light interference and can achieve the best anti-reflection effect. The thickness of the waterproof and oil-proof film is relatively thin, usually around tens of nanometers. If the thickness is not appropriate, the performance of the coating will be greatly reduced. For example, if the thickness of the anti-reflection film is not correct, it may not be able to effectively reduce light reflection.