You know how many sunglasses knowledge
High school physics spectrum, we all learned in simple terms, we see the visible wavelength range is 380 ~ 780 nm, for the light, the sunglasses is to reduce the effect of light through, reduce eye summer light. For we can't see the wavelength range of 100 ~ 380 nm, the ultraviolet ray, its impact on our eyes actually is bigger than the sun light is very much. The time of exposure to ultraviolet rays for eyes, long, easy to cause the chronic eye diseases such as cataracts, macular degeneration, some will also appear in a short period of time the eye pain, photophobia, decreased vision, corneal edema and other symptoms. So need a pair of sunglasses in summer to against the strong light and ultraviolet. Sunglasses factory YC9708 general sunglasses C7 black box silver leg/uv lens ash is sunglasses, a necessary function, it has nothing to do with the lens color and light transmittance, usually by coating the implementation, usually in the following three kinds of express way: 1. Labeled 'UV400' : this means that the lens to block below the wavelength of 400 nm uv and visible light; As long as through the lens of the ultraviolet light is lower than 2%, even if qualified; 2. Labeled 'UV', 'UV' : this says the lens to block below 380 nm UV; As long as through the lens of the ultraviolet light is lower than 2%, even if qualified; 3. Labeled '100% UV absorption' : this means that the function of the lens is 100% for UV absorption; But through the lens of the ultraviolet light is lower than 0. 5%, even if qualified. Under the condition of without considering other factors, choosing a uv protection sunglasses, can buy in accordance with the above 3 points. And usually, glasses will be marked on the tag. General polarized sunglasses uv protection function is better. Sunglasses not only cool play handsome act the role of article, it also is to protect his eyes from the damage of special tools, actually the function of the sunglasses is far more than these, just you don't know. If you want to know more about the powerful features of the sunglasses, can focus on sunglasses glasses factory network, encyclopedia of glasses are right here waiting for you!
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