9-layer Coating Sunglasses? Are They Important To You?
von BrightDr. An Jul 26, 2022
As we said before, the lenses are coated in single or multiple layers to reach the UV400 index. The production of such lenses can be as cheap as 1 dollars or as expensive as 10 dollars. It depends on the conscience of the manufacturer.
The lenses are coated to reflect high density light and reduce glare, thus reducing the amount of visible light that can reach the eyes. A good filter lens, when coated, has a better optical performance and is clearer.
Lenses are coated by spraying a thin layer of vaporized metal on the surface of the lens in a vacuum chamber. The coating colors usually refer to silver, blue, reddish-brown or orange. Most of them are just for aesthetic fashion and do not have the function of eye protection. Metallic coatings are mostly chrome, but they are not as wear resistant as high-performance titanium or quartz dielectric coatings. Lens coatings generally increase the depth of color evenly throughout the sunglasses.
There is also a coating, called "AR (anti-reflection)", which is on the side near the eye and serves to prevent ghosting and substantially improve visual clarity, a very obvious wearing effect.
Although some coatings can be used to harden the lens surface, they are still very delicate and should be used with care. Any coating has a life span. If the coating is damaged, the lens is scrapped.
The most obvious is myopia glasses. We should replace new prescription glasses every year or two, because we wipe to clean them every day, which will damage the lenses a lot.