In the previous article, we discussed “What are the best sunglasses for rowing?”. In this article, let’s talk about “How to tell if sunglasses are polarized?”.
What is a polarizer?
The polarizer is manufactured according to the principle of polarization of light. We know that when the sunlight is projected on the road or water, it directly irritates the eyes and makes the eyes feel dazzling, tired, and unable to see for a long time. Long-term exposure to direct sunlight will also cause rapid decline in vision, resulting in nearsightedness, hyperopia, and astigmatism, or cataracts and so on. The special effect of the polarizer is to effectively exclude and filter out the scattered light in the beam. The light can be injected into the visual image of the eye on the transmission axis of the right track, so that the visual field is clear and natural.
Features of polarizer
Although polarized lenses can filter out a lot of irregular light interference and avoid glare, the polarizing effect will be weakened, if the curvature of the lens cannot be in the optical standard refractive state. Also,?this lens will affect the authenticity of the image, and the durability is poor. The generally polarized sunglasses on the market are made of fibers sandwiched with a polarizing film. It is different from optical glass polarized sunglasses because of its soft texture and unstable arc. After the lens is fitted with the frame, it is difficult for the lens to reach the optical refractive standard, and the image is loose and deformed.(https://www.koalaeye.com/collections/polarized-sunglasses)
Due to the instability of the arc, the lens is deformed, which directly leads to the poor clarity of the transparent image and the distortion of the image, which can not achieve the normal visual effect. And the surface is easy to scratch and wear, and is not durable. The polarized lens is formed by pressing multiple layers of thin resin material. Each layer has a different function. The middle layer is the polarizing layer. Its principle is like a blind, which can filter out stray reflected light. The second and third layers can filter 99.9% of harmful ultraviolet rays and reduce the light intensity, and the function is no different from ordinary sunglasses. The fourth and fifth layers of polarized lenses are anti-impact layers to make the lenses difficult to break. The sixth and seventh layers are strengthened to make the lenses difficult to wear. The polarizer can filter out harmful light to protect the eyes.
How to tell if sunglasses are polarized?
Non-polarized sunglasses generally only have the two basic functions of shielding strong light and filtering ultraviolet rays, and their efficiency in filtering ultraviolet rays is low. However, in our daily life, in addition to strong light and ultraviolet light, when light passes through uneven roads, water surfaces and other places, irregular diffused light will also be generated, which will cause blurred vision and fatigue in the eyes. Polarized sunglasses can filter out this kind of light, only absorb the reflected light of the object, and truly present what you see, making the field of vision clearer, thereby reducing visual fatigue. In addition, because of its high-efficiency filter layer, polarized sunglasses have a blocking rate of 99% against ultraviolet rays, which can effectively reduce the damage of ultraviolet rays to the eyes. When judging whether the sunglasses are polarized lenses, you can rotate the sunglasses up to 45° clockwise. If the color of the lens changes at this time, and the color of the sunglasses returns to normal after turning the sunglasses back to the original position, then it can be judged that the sunglasses are polarized. And if you can’t see the change in the color of the sunglasses lens no matter how you turn it, then you can judge that the sunglasses are not polarized.
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