Why do spectacle lenses fog up?
The fog on the surface of the lens is essentially related to the saturation pressure and water vapor liquefaction. The air is full of water molecules, which are constantly doing irregular movements. When there is no temperature difference, water molecules keep hitting the surface of the lens and will keep bouncing off. The lower the temperature, the slower the speed of movement. Therefore, when water molecules hit the cold lens from the hot air, on the one hand, they move too slowly to fly out in time. On the other hand, because of the relatively low temperature of the lens itself and its vicinity, the water vapor will liquefy. As a result, more and more water will accumulate on the lens and form small droplets, eventually forming a foggy layer. As the lens heats up, the mist evaporates back into the air, and the fog disappears.
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What are acetate glasses?
Acetate spectacle frames are the most common spectacle frames on the market. It has a light texture and good gloss, which is very popular among young men and women. Acetate frames are lighter and generally considered to be better than plastic frames. Acetate fiberboard is known for its Hypo-Allergenic, so it is a popular choice for people with sensitive skin. Unlike some plastic or metal frames, they can cause allergic reactions. However, you will find that acetate frames are usually more expensive than ordinary plastic frames. So what is the reason?
Acetate is one of the first synthetic fibers. It was not used to make glasses until the late 1940s. The higher the quality of acetate, the better the gloss and transparency. Not easy to burn is one of the biggest characteristics of acetate fiber. Also because of the non-combustibility of acetate fiber, this material can hardly be affected by ultraviolet radiation to change color, and can better maintain the gloss of the spectacle frame. Moreover, it is light and hard, and it is not easy to deform.
Pay attention to the wearing of myopia sunglasses when driving.
Some drivers are slightly myopic, usually driving without wearing a myopic mirror. There is no problem. But once you wear sunglasses, the problem comes: your eyes are more likely to tire and your vision will decline, just as your driving vision will be affected at night. Therefore, for the driver of slight myopia, there is no problem in usually driving, but if you want to wear sunglasses, you must be equipped with the lens of myopia degrees.
How to adapt to progressive lenses?
People who are prone to motion sickness or have inner ear diseases may suffer dizziness, nausea, vomiting, and other symptoms due to their inability to tolerate the slight deformation of the visual objects, so they need to pay more attention when wearing them. For people who have not worn reading glasses before, it is not recommended to wear graded multi-focus glasses directly because their eyes will not be able to adapt quickly.
Why are titanium glasses so expensive?
Light Weight. The term 'pure titanium' means a titanium metal material with a purity of more than 99%. A mineral containing titanium was found in 1791, but pure titanium was not produced until 19. Pure titanium glasses are lighter than titanium alloy glasses. For frames of the same design or appearance, titanium frames weigh only half as much as other ordinary metal frames, reducing the load on the bridge of the nose.
Why the lens coating is not uniform?
Sometimes we find differences in the color between the convex and concave surfaces, between the center and the edge of the lens, and the anti-reflection effect between the convex and concave surfaces. his is mainly because the lens coating is that it is plated on one surface and then turned over to another surface. And Areas with small curvature changes are easy to coat. So the center of the lens has reached the desired thickness of the film but the edge has not. At the same time, the different curvature of the convex surface and concave surface causes the different coating speed. So the surface of the lens will show green in the center and lavender red or some other color at the edges.