What are polarized sunglasses

Polarized sunglasses are mainly a mechanism for sun protection and eye protection. They are also a type of sunglasses. They mainly include linear polarization, elliptical polarization and circular polarization. If it is linear polarization, it is mainly projected along the propagation route of space. Linear propagation mainly produces some due east direction of vibration direction and propagation direction, which can be used as linear polarization and is also frequently used in daily life.

In addition to the basic UV protection function, it can also protect against glare and light sources reflected from the road. It can be worn while driving, fishing, traveling and in daily life. It is mainly divided into ski goggles, fishing goggles and polarized sun goggles. You can also use some common purchasing methods to purchase them in daily life. Its main principle is to protect your eyes.

Polarized sunglasses block uncomfortable bright light while protecting your eyes from harmful UV rays. All this is possible thanks to metal powder filters that “select” the light as it hits. Polarized sunglasses can selectively absorb part of the wavelengths that make up the sun's rays because they use very fine metal powder (iron, copper, nickel, etc.). In fact, when light hits the lens, it is subtracted due to a process called "destructive interference". That is, when certain wavelengths of light (in this case UVA, UVB, and sometimes infrared) pass through the lens, they cancel each other out on the inside of the lens, toward the eye. The overlapping of light waves is no accident: the crest of one wave and the trough of its adjacent wave cancel each other out. The phenomenon of destructive interference depends on the refractive index of the lens (that is, the degree to which light rays are deflected when passing from air to different substances), and also on the thickness of the lens. Generally speaking, the thickness of the lens does not vary much, while the refractive index of the lens varies depending on the chemical composition.

Polarized sunglasses provide another mechanism for protecting your eyes. The reflected light from the asphalt road is a relatively special polarized light. The difference between this reflected light and light directly from the sun or any artificial light source lies in the problem of order. Polarized light is composed of waves that vibrate in one direction, while ordinary light is composed of waves that vibrate in non-directional directions. This is like a group of people walking around in disorder and a group of soldiers marching in an orderly manner, forming a sharp contrast. Generally speaking, reflected light is an orderly light. Polarized lenses are particularly effective at blocking this light because of their filtering properties. This type of lens only allows polarized waves vibrating in a certain direction to pass through, just like "combing" the light. For the problem of road glare, using polarized sunglasses can reduce light transmission because it does not allow light waves that vibrate parallel to the road to pass through. In fact, the long molecules of the filter layer are oriented horizontally and can absorb horizontally polarized light. In this way, most of the reflected light is eliminated without reducing the overall illumination of the surrounding environment.

Finally, polarized sunglasses have lenses that darken when the sun's rays hit them. When the lighting faded, it became bright again. This is possible because of the silver halide crystals. Under normal circumstances, it keeps the lens perfectly transparent. Under the irradiation of sunlight, the silver in the crystals is separated, and the free silver forms small aggregates inside the lens. These small silver aggregates are in the shape of irregular jagged blocks. They cannot transmit light but can only absorb it, resulting in the darkening of the lens. In dark or light conditions, the crystals reform and the lens returns to its bright state.

The above is a brief introduction to polarized sunglasses. In addition to the basic function of UV protection, they can also protect against glare and light sources reflected from the road. They can be worn for driving, fishing, traveling and daily life. They are mainly divided into ski goggles, fishing goggles and polarized sun goggles. At the same time, you can also use some common purchasing methods when purchasing them in daily life.