Why does the phone lens have different colors?

With the popularity of smart phones, everyone is slowly getting used to taking photos with their mobile phones. Some attentive friends may notice that the mobile phone lens also has different colors, some green, some blue, some red, why are these colors? What role does these colors have?

In fact, in addition to the phone lens, we usually use digital camera lenses, telescopes, glasses and other lenses are colored. These colors are mainly due to the thin layer of coating on the surface of the lens, so the different colors of the lens surface are mainly due to the use of different coatings. The coating of various colors of the lens is not to please the user. The imaging of the lens by the coating has a very important role.

Coating mainly has the following two roles:

1, increase through. When light passes through the lens, about 4% to 10% of light is reflected by the lens (reflectivity will be higher with plastic lenses). Maybe you would think that 90% of the light transmittance is actually better, but the general lens is composed of several lenses, such as the Meizu MX2 and OPPO Find 5 released earlier called the lens consists of 5 lenses, such a In fact, only 59% of the light reaches the sensor.

In addition, the light that is reflected inside the lens is reflected repeatedly inside the lens, resulting in glare or ghosting on the sensor. Therefore, how to increase the transmittance is a very important issue. Nowadays, the commonly used method is to add a layer of coating on the surface of the lens. These coatings can greatly increase the transmittance of a certain spectrum of light.

However, since the light we need to increase the transparency is not monochromatic, it has a certain bandwidth. The single-layer antireflection film can only have a complete anti-reflection effect on a single wavelength of monochromatic light. Therefore, we need multi-layer coating technology to improve the coverage of light that can be enhanced. In addition, the different reflectivity of each coating layer can also increase the throughput of light.

When you look at the lens surface, the color you see is the reflected light. In general, the less light reflected back, the more effective the coating will be.

2, color correction. Because the material or some components in the lens may cause the lens to absorb some of the high color, resulting in the final image color cast. In order to eliminate this chromatic aberration, lens manufacturers will add coatings of other colors, such as amber, cyan, purple or blue, on the basis of the lens without additional glare and ghosting. These coatings can balance the final lens. Imaging color.