In the previous article, we discussed “How can you promote myopia sunglasses?”. In this article, let’s talk about “What to know about polarized sunglasses?"
How did polarizers come about?
In 1926, Edwin H. Land, a chemistry major at Harvard University, was walking down Broadway in New York City under the glare of car and store signs. He realized the safety hazard and wondered what he could do about it. In 1929, Land invented and patented the world's first synthetic polarizer. He named his polarized product Polaroid. Dr. Land founded Polaroid in 1937, focusing on sunglasses and scientific research for related departments. During that time, he invented glasses for watching 3-D movies, led the development of the U-2 spy plane, and served as a technical adviser to presidents from Eisenhower to Nixon. In 1944, Dr. Land invented the first instant imaging camera. After 1948, Polaroid 95 cameras were officially released to the public, and it was this camera that started the glory of Polaroid for more than half a century.
A polarized lens is a kind of sunglasses lens.
The colored lenses
Most colored lenses are made of glass, which is made by adding chemicals to the lenses to give them a color that absorbs light at specific wavelengths. They are especially applicable to professional needs for soldiers, pilots, and so on.
The tinted lenses
Most of them are glass resin materials. The process of dyeing a resin lens is called percolation (Heat increases the distance between the molecules on the surface of the lens so that the dye molecules can seep in). The lenses are available in a variety of colors and can be bicolor or gradient. They are especially suitable for shading, giving attention to fashion and decoration.
Anti-reflective protective lenses
Also known as "mercury membrane lens," these lenses are coated with a thin layer of magnesium fluoride to prevent bright light from reflecting, allowing you to see more clearly, without interference from bright light. They are especially suitable for bright light environments, such as beaches, snow, etc.
The Photochromic Lenses
They are also called "photosensitive lenses". A photochromic film layer is formed on the surface of the lens by a special process. When met with ultraviolet light, the originally transparent lens will become a colored lens, back to the room and back to colorless transparent. They are especially suitable for people who frequently have outdoor activities and people who have refractive errors (need to test prescription lenses).
The polarized lenses
To filter out the glare of the sun's rays on water, land, or snow, polarized lenses are added to the lenses. They are ideal for outdoor activities (e.g., sea activities, skiing, or fishing). They are especially suitable for driving, outdoor sports, fishing, etc. So polarized lenses are just one type of sunglasses.
Polarized lenses are also different.
Polarized lenses with relatively good quality are: The first generation of a polarized lens is acetic acid fiberboard technology. The representative products are diacetic acid fiberboard (CAB) (now almost obsolete) and tri acetic acid fiberboard (TAC). The main production process features are as follows: the acetic acid fiberboard is used as the carrier of polarized film for lamination, and then cut according to the size of the actual need. After heating, the fiberboard is softened and then formed by pressing and bending. Mainstream sunglasses on the market use TAC polarizer, and the commonly used thickness is generally 0.7mm, 1.0mm (the most common), 1.4mm.
The second generation is thermosetting polarized technology. The thermosetting material is injected into the mold and cooled after forming. Representative products are glass polarizer and resin polarizer. Under the premise of maintaining the original polarized performance, the size stability of the polarized lens is solved, and the optical performance is better improved. Glass and resin polarized lenses have a common feature: the lens is fragile during processing (finished sunglasses lenses), the glass is easy to crack, and the resin is easy to crack edge. So the second generation of polarizers did not become a market leader.
The third generation is the era of thermoplastic technology. Its main feature is the use of polymer engineering plastics, using an injection molding process, with the perfect combination of polarized film and engineering plastics. Under the premise of maintaining the original polarizing performance, the size stability of the polarizing lens is guaranteed, and the optical performance of the lens is also guaranteed, and the anti-ultraviolet performance can reach more than 99%. The representative products are PC polarized lenses and Nylon polarized lenses (or TR polarized lenses). The third generation of polarized lenses overcomes the problem that the traditional polarized lens is easy to deform after the frame. It also solves the problem of heavy and fragile polarized light of glass. At the same time, the polymer material has strong impact resistance. The common thickness is generally between 2.0mm and 2.3mm.
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