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Vacuum coating is a new process for preparing thin films under vacuum conditions using physical or chemical methods, and absorbing a series of new technologies such as electron beam, molecular beam, ion beam, plasma beam, radio frequency, and magnetron, providing scientific research and practical production.
Common types of thin films
1. Anti reflective film/anti reflective film:
Anti reflection film/anti reflection film is a type of film that uses the interference between the reflected light from the thin film and the reflected light from the substrate to adjust the reflectivity and affect the transmittance. When the film layer is one-quarter of the wavelength of the light wave, the two sets of reflected light interfere and cancel each other out, achieving the anti reflection effect. This is because according to energy conservation, the transmittance will increase while the absorption rate remains basically unchanged, thus achieving the anti reflection effect.
For example, alternately coating titanium oxide and silicon oxide on a glass substrate, with a total of six layers, when we design the thickness of the six layer film to achieve a reflectivity of less than 1% for visible light waves of 400-700nm, the transmittance will correspondingly increase, as shown in the following figure:
In our daily lives, we often come into contact with anti reflective films/anti reflective films. For example, camera lenses are often coated with anti reflective films to enhance the shooting effect; Car navigation systems are often coated with anti reflective and anti glare films to make the images clearer, and can also reduce glare, blurred vision, and other issues caused by reflections.
2. Cut off film:
Cut off film is a thin film that exhibits high reflectivity to specific wavelengths of light by designing and adjusting the film structure and thickness.
At present, we often see products coated with cutoff films in our daily lives. For example, anti blue light mobile phone screens are coated with blue light cutoff films, which have a high reflectivity effect on blue light bands and a high transmittance effect on other visible light bands;
By alternately plating titanium oxide and silicon oxide on a glass substrate, we can achieve high reflectivity for blue light with a wavelength of 400-450nm and high transmittance for other visible light with a wavelength of 500-700nm by designing and adjusting the number of layers and the thickness of each layer, thus achieving the effect of preventing blue light, as shown in the following figure:
3. Color film:
Color film is designed to adjust the structure and thickness of the film layer, so that it presents different reflectivity and transmittance to visible light in different bands, thereby adjusting the color it presents.
For example, the following figure shows the reflectivity curve of a color film designed for a certain product. It can be seen that its reflectivity is high in the 400-500nm blue purple wavelength range, while its reflectivity is low in other visible light ranges of 500-700 wavelengths.
Therefore, it can be seen that this color film mainly reflects blue purple light, which means the product appearance appears blue purple.
In our daily lives, we often come into contact with color films. For example, the anti-counterfeiting labels of certain products are coated with color films, which use the principle of different relative film thicknesses corresponding to incident light at different angles to make their anti-counterfeiting labels appear different colors from different angles; The gradual color change of the back cover of a mobile phone is also a type of color film, and so on.
4. Waterproof membrane:
Waterproof film is a top film coated on a product with anti oil and anti water properties, which reduces the contact area between water, dust and other dirt and the product at a 110 degree angle, making it less likely to adhere to the surface of the product. Therefore, its surface will be smoother and smoother, increasing its anti pollution functions such as waterproof, anti fog, dustproof, anti fingerprint, etc.
Waterproof film has been widely used in our daily lives. For example, most mobile phone screens and their tempered films are now coated with waterproof film, making their surfaces smoother, smoother, and more tactile, and enhancing their anti pollution functions such as waterproof, anti fog, dustproof, and anti fingerprint.
Prospects of Vacuum Coating
Although the development time of vacuum coating technology is not long, its development is quite rapid. As an environmentally friendly and pollution-free technology, it is increasingly demonstrating its numerous advantages, especially in reducing costs and expanding product added functions. The role it plays in daily life and science and technology is becoming increasingly significant, and it is increasingly valued and welcomed by a large number of scientific and technological researchers.
