In the previous article, we discussed “What color tint is best for sunglasses?”. In this article, let’s talk about “Do fake Ray-Bans have UV protection?”.
The sun is shining in the sky, and summer is here again. The most basic function of sunglasses is to protect the eyes from ultraviolet rays. I've unfortunately just bought some fake Ray-Ban sunglasses made in China. Do the fake Ray-Ban sunglasses have UV protection? So, how to tell if sunglasses are UV-resistant?
Anti-ultraviolet coating
The reason why sunglasses can block ultraviolet rays is that a special coating film is added to the lenses. While blocking and absorbing ultraviolet rays, it also blocks part of the visible light, which reduces the transmittance of the lenses. Therefore, high-quality sunglasses have a strong ability to block ultraviolet rays and their transmittance will not descend. And the coating has a certain degree of hardness and is not easy to wear and tear.(https://www.koalaeye.com/collections/polarized-sunglasses)
UV index
The UV index is the effect of filtering ultraviolet rays, which is a very important criterion for buying sunglasses. Light with a wavelength of 286nm-400nm is called ultraviolet light. Generally speaking, a 0% UV index is impossible. The UV index of most sunglasses is between 96% and 98%.
Sunglasses marked as 'UV400' can protect against more than 90% of ultraviolet rays, and their lenses are specially processed to block ultraviolet rays with a wavelength of less than 400nm.
How to tell if sunglasses are UV resistant?
1.Obvious marks such as 'UV' and 'UV400' can be seen on the labels or lenses of anti-ultraviolet sunglasses. Sunglasses with anti-ultraviolet function generally have the following explicit methods.
a. Mark 'UV400': This means that the cut-off wavelength of the lens to ultraviolet is 400nm, that is, the maximum value τmax(λ) of the spectral transmittance at a wavelength below 400nm is not greater than 2%.
b. Mark 'UV' and 'UV protection': This means that the cut-off wavelength of the lens to ultraviolet is 380nm, that is, the maximum value τmax(λ) of the spectral transmittance at a wavelength (λ) below 380nm is not more than 2%;
c. Mark 100% UV absorption': This means that the lens has the function of 0% absorption of ultraviolet rays, that is, its average transmittance in the ultraviolet range is not more than 0.5%.
2. In the absence of equipment, ordinary people can also detect whether the sunglasses have UV protection. Take a banknote, and put the sunglasses lens on the anti-counterfeiting watermark. Irradiate on the lens with a money detector or a money detector. If you can still see the watermark, it means that the sunglasses are not UV-proof. If you can’t see it, it means that this pair of sunglasses is UV resistant.
All in all, wearing sunglasses is very important because it can not only make you look cool but also protect your eyes. When you get your sunglasses, you can check if sunglasses are UV resistant by yourself. Moreover, it is recommended that buying sunglasses from the official website and stores.
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