Production principle of Polarized Sunglasses

Many people buy polarized sunglasses, there will be a question, what is the principle of making polarized sunglasses? The following is the introduction of Zhejiang Kaixin Photoelectric Technology Co., Ltd. (Heel). Polarized Sunglasses block uncomfortable bright light and protect the eyes from ultraviolet rays. All this is due to metal powder filters, which "select" light as it enters. Polarized Sunglasses selectively absorb part of the spectrum that makes up the sun's light because they rely on very fine metal powders (iron, copper, nickel, etc.). In fact, when light hits the lens, it is subtracted based on the so-called "destructive interference" process.

Production principle of Polarized Sunglasses

That is to say, when certain wavelengths of light (in this case, ultraviolet a, ultraviolet b, and sometimes infrared) pass through the lens, they counteract each other inside the lens in the direction of the eye. The overlap of light waves is not accidental: the combination of a wave crest with its adjacent trough results in cancellation. The phenomenon of destructive interference depends on the refractive index of the lens (i.e. the degree to which light deviates as it passes through different substances from the air) and on the thickness of the lens. Generally speaking, the thickness of the lens varies little, while the refractive index of the lens varies according to the chemical composition.


Polarized sunglasses provide another mechanism to protect the eyes. The reflected light of 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 lies in order. Polarized light is formed by waves vibrating in one direction, whereas ordinary light is formed by waves vibrating in an undirected direction. It's like a group of random people walking in disorder and a group of soldiers marching in perfect order, forming a sharp contrast. Generally speaking, reflected light is an orderly light. Polarizing lenses are particularly effective in blocking this light, because its filtration function is playing a role. Such lenses only allow polarized waves to vibrate in a certain direction, just like "Combing" the light. For road reflections, the use of Polarized Sunglasses reduces the transmission of light because it prevents light waves that vibrate parallel to the road from passing through. In fact, the long molecules in the filter layer are oriented horizontally and absorb horizontally polarized light. In this way, most of the reflected light is eliminated, and the ambient illumination is not reduced.

Polarized Sunglasses

Finally, the lenses of polarized sunglasses can be dimmed after the sun's rays are coming. When the illumination is weakened, it becomes bright again. The reason for this is because the crystal of silver halide is at work. Under normal circumstances, it keeps lenses perfectly transparent. Silver in the crystals is separated by sunlight, and small aggregates of free silver form inside the lenses. These small aggregates of silver are irregularly interlaced pieces of canine teeth that do not transmit light, but absorb it, resulting in darkening of the lenses. In the case of light and darkness, the crystals form again and the lenses return to the bright state.

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