How to identify the quality of sunglasses
The quality of sunglasses can be judged from two aspects of quality and aesthetics. Aesthetics has personal factors, and quality has certain standards. The quality of sunglasses mainly refers to the quality of the lenses. At present, the universal standard in the world is the US Food and Drug Inspection Agency (F??D??A) standard.
1. According to the F??D??A standard, the lens should filter out more than 90 percent of the ultraviolet rays in the sunlight while ensuring the light transmittance. The lens should be labeled ‘UV-100PROTCT10N’. When filtering out UV rays, the label ‘UV-400PROTCT10N’ should be attached, so it is important to check the UV label on the lens.
2. The lens cannot have the ‘degree’ that only optical lenses have. Generally, if the diopter exceeds 15 percent, there will be a feeling of dizziness when wearing it.
3. The lens must have high strength and pass the impact resistance test. Generally speaking, the strength of plastic sheet (propionic acid or cellulose acetate), resin sheet and glass sheet is from small to large.
How Distinguish the quality of sunglasses lenses
1, Material of lenses
Glass lenses: wear-resistant, but Relatively speaking, its weight is heavier than other materials, and it is easy to break.
Polymer resin lens: This lens is lighter than glass lens, impact-resistant, not easy to break, but has low hardness, so it is easy to fluff and scratches.
2. The refractive index of the lens
The higher the refractive index, the thinner the lens and the higher the price. Such as the optical characteristics of the lens: Sunglasses
are flat lenses, can not have a diopter, and should not have optical defects that affect vision.
A simple identification method is to put the sunglasses in front of the eyes, observe the distant target through the lens, such as window frame or door frame, etc., and then move the glasses up and down, and the target should not be swayed or wavy. .
3. Lens color
Sunglasses are divided into dark and light colors, and there should be no color distortion. The choice of the color depth of the lens should be determined according to the required activity place. Choose different colors for different light sources and different usage occasions. The color of the lens will affect the shading effect. Dark shades are needed for sunglasses to effectively block the summer sun, but if you’re riding or driving, you shouldn’t choose lenses that are too dark. In addition, when the sunglasses are used for daily driving, they also need to have the ability to recognize the signal lights of different colors.
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