How to choose sunglasses in summer?

Posted by sere on February 25th, 2021

There are so many kinds of glasses on the market now, especially the sunglasses. As a result of the sun's irradiation in summer, a lot of people can choose sunglasses to keep out ultraviolet ray, but here need to pay attention to the choice of sunglasses..... . Here, Timeless Sunglasses Manufacturers has a quick guide to choosing Sunglasses this summer.

How to choose sunglasses in summer

1. Wear sunglasses in summer to try to have a feeling of dizziness and headache. There are also a few myopic sunglasses that indicate degree on market now to sell, do not pass because pupil distance and other indicators vary from person to person, if do not have the guidance of professional personage so, consumer had better not choose this kind of sunglasses that has degree.

2. To observe whether the lens has scratches, impurities, bubbles, stripes, check the outer packaging of sunglasses, regular sunglasses should be marked with product name, color, diameter, quality level, the name of the manufacturer and trademark, mirror or tag marked with anti-UVA, UVB and CE signs of the sunglasses to ensure that a certain amount of ultraviolet.

3. Hold the corners of the sunglasses against the fluorescent lamp and let the reflective strip of the mirror roll gently. If you find that the sunlight reflected by the mirror appears wavy and distorted, it shows that the lens is not smooth, and such a mirror will damage your vision.

4. The color of sunglass besides the color of skin according to oneself, face shape, dress will match outside, still should choose according to go in and out place. Generally speaking, black, tan and gray filter well; Grey lens can be balanced absorption of any color spectrum, after wearing the lens to see the scene will only darken without obvious color difference; The tawny lenses filter out large amounts of blue light and improve visual contrast and clarity, especially in polluted or foggy conditions.

5. Lenses should be flat, high transparency, lens material has glass and resin, and a good lens should be polarised lens. It is made of a synthetic resin as light and precise as a contact lens. It consists of seven thin sheets and two superhard wear-resistant layers. The second and sixth layers are shatter-proof strengthening layers; The third and fifth layers are ultraviolet filter layers, and the middle layer is a polarizing filter layer. Polarised lenses are popular sunglasses that effectively filter out reflected light and harmful ultraviolet rays, and are resistant to shattering and abrasion.

6. How to choose the right shade of sunglasses for us in summer? A simple way to test yourself is to wear sunglasses in front of a mirror so that you can barely see your pupils. If the color is too light, the filtering effect is too small. Too dark color will affect vision and weaken color sense. Sunglasses of colorful light color that is popular this year, do not use in activity on seaside water, in the snow field that glances strongly and sunshine falls very intense sun, and should wear sport sunglass, they use the saturated color with gorgeous color mostly, can absorb or reflect more visible light.

How to wear sunglasses?

Sunglasses are generally divided into light and dark categories and are made up of a variety of colors. Judge the quality of sunglass bad, the key should examine a few technical indicators such as top coke degree and prism degree, transmission ratio characteristic, surface quality and inner fault, assembly precision and plastic requirement.

A good pair of sunglasses can help shade the sun and decorate the appearance. But in the market, the actual situation is not optimistic. Some vendors are taking advantage of consumers' lack of knowledge about the quality of sunglasses by making them with shoddy, inexpensive window glass or other inferior materials. The uniformity of these materials is poor, containing streaks, bubbles and other impurities, can not block ultraviolet light, does not meet the physiological requirements of the human eye. What's more, the use of poor quality plastic sheets with very low visible light transmittance but very high UV transmittance to make sunglasses harms consumers.

How to choose and wear sunglasses? Expert reminds consumer, must not pay attention to the style of sunglass only, should pay attention to its internal quality more. For qualified sunglasses, the transmittance of UVA at wavelengths between 315nm and 380nm should not exceed 10%, and the transmittance of UVA at wavelengths between 280nm and 315nm should be zero. Wearing these sunglasses can protect the cornea, lens and retina of the eye from UV damage. A few cheap sunglass cannot filter ultraviolet ray not only, can because keep out after visible light instead, the irradiate that makes ultraviolet ray is more remarkable, this kind of inferior sunglass is inferior to do not wear.

Sunglasses belong to the series of flat mirrors. Set according to national standard, sunglass allows to contain the refraction of plus or minus 8 degrees only more, exceed this error range is unqualified product. According to scientific research personnel to inspect the sunglass on the market, the refraction that has nearly 3 into sunglass exceeds acceptable poor, some is as high as 20 many degrees even. The expert points out, the consumer of normal vision wears this kind of sunglass, as wearing a pair of myopic lens or farsightedness lens, after a summer passes, consumer can be by inferior sunglass "cultivate" become myopia or farsightedness patient. When you wear sunglasses after dizziness, nausea, dazzling and other symptoms, should immediately stop wearing.

What is the principle of sunglasses?

Sunglasses can block uncomfortable bright light and also protect the eyes from damaging ultraviolet rays. All this is thanks to metal powder filters that "select" light as it hits. The tinted glasses selectively absorb some of the wavelengths that make up the sun's rays because they use very fine metallic powders (iron, copper, nickel, etc.). In fact, when light hits the lens, it is subtracted by a process called destructive interference. That is, when certain wavelengths of light (in this case UVA, UVB and sometimes infrared) pass through the lens, they cancel each other out on the inside of the lens, toward the eye. The overlap of light waves is no accident: the crest of one wave and the trough of its nearest counterpart cancel each other out. Destructing interference depends on the refractive index of the lens, which is how much light diverges as it passes through different substances from the air, and also on the thickness of the lens. Generally speaking, the thickness of the lens does not vary much, while the refractive coefficient of the lens varies according to the chemical composition.

Polarizing sunglasses offer another mechanism for eye protection. The reflected light of asphalt is a special kind of polarized light. The difference between this reflected light and light directly from the sun or from any artificial source is a matter of order. Polarized light is made up of waves that vibrate in all one direction, whereas ordinary light is made up of waves that vibrate in no direction. It was like the contrast between a group of men moving at random in disorder and a group of soldiers marching in step. In general, reflected light is an ordered kind of light. Polarized lenses are particularly effective at blocking this light because of their filtering properties. The lenses allow only polarized waves that vibrate in a certain direction to pass through, as if combing light. For road reflections, using polarizing sunglasses can reduce the transmission of light because it does not let through light waves that vibrate parallel to the road. In effect, the long molecules in the filter layer are directed horizontally and can absorb horizontally polarized light. In this way, most of the reflected light is eliminated without reducing the overall illumination of the surrounding environment.

The lenses of color changing sunglasses darken when the sun's rays hit them. When the lighting waned, it became bright again. This is possible because the crystal of silver halide is at work. Under normal conditions, it keeps the lens perfectly transparent. In the light of the sun, the silver in the crystal is separated, and the free silver forms small aggregates inside the lens. These small silver aggregates, irregular patches with interlocking teeth, do not transmit light but absorb it, which darkens the lens as a result. In the case of dim light, the crystals form again and the lens returns to its bright state.

For more information about Sunglasses, please contact Timeless Sunglasses Manufacturers.