Why Polarized Sunglasses Are More Comfortable and Softer than Regular Sunglasses

The polarized function of sunglasses can block the glare in the sun, and at this time, it can protect the eyes from ultraviolet rays. It’s all thanks to metal powder filter mounts that sort out the clutter into the right light as it hits the eye, so that the light that hits the eye is softened.

Polarized sunglasses can selectively absorb the local bands that make up the sun’s rays because they use very fine metal powders (iron, copper, nickel, etc.). In fact, when light hits the lens, it is subtracted based on a process called “destructive intervention”. That is, when certain wavelengths of light (in this case UV-A, UV-B, and sometimes infrared) pass through the lens, they cancel each other out on the inside of the lens, toward the eye. The superimpositions that make up light waves are not accidental: the crests of one wave merge with the troughs of the wave next to it, causing them to cancel each other out. The phenomenon of destructive interference depends on the lens’ index of refraction (the degree to which light rays deviate from air as they pass through different substances), and also on the thickness of the lens.

Generally speaking, the thickness of the lens does not change much, while the refractive index of the lens varies according to the chemical composition.

Polarized sunglasses provide another mechanism for eye protection. The reflected light of the asphalt road is a special polarized light. The difference between this reflected light and light coming directly from the sun or any artificial light source is a matter of order. Polarized light is composed of waves that vibrate in one direction, while ordinary light is composed of waves that vibrate in no direction. This is like a group of people walking around in disorder and a group of soldiers marching at the same pace, forming a clear antithesis. Generally speaking, reflected light is a kind of ordered light. Polarized lenses are especially effective at blocking this light because of its filtering properties. This kind of lens only passes through the polarized waves vibrating in a certain direction, as if “combing” the light. Regarding the problem of road reflection, the use of polarized sunglasses can reduce the transmission of light, 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 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 as the sun’s rays hit them. When the lighting faded, it became brighter again. This is possible due to the silver halide crystals at work. Under normal conditions, it keeps the lens perfectly transparent. Under the irradiation of sunlight, the silver in the crystal is separated, and the free silver forms small aggregates inside the lens. These small silver aggregates are criss-cross irregular blocks, they can not transmit light, but can only absorb light, the result is to darken the lens. Under light and dark conditions, the crystals regenerate and the lens returns to a bright state.

Post time: Dec-01-2022