by Max Bellamy
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Polarized sunglasses are designed to absorb the reflective solar glare from flat surfaces like water, snow, and highways. These glasses can absorb up to 97% of the glare from such surfaces. Polarized sunglasses are not just a fashion accessory but also a safety device for navigators, water sportsmen, skiers, and drivers.
Shimmering water and pristine white snow can create a tremendous reflective glare from the sunlight incident on it. Even long road stretches can produce such glares. The iris in our eye has a natural mechanism of becoming narrow and blocking light, but it is unable to block such bright glares, which is where polarized sunglasses become useful.
Edwin H. Land invented polarized lenses in 1936. Ordinary light travels in the form of waves that can vibrate in all directions. Polarized sunglasses polarize the light, that is, they make the light vibrate only in one direction. Generally, surfaces that produce glares have horizontally polarized light. Sunglasses are fabricated with vertical polarization to block much of the incident light and reduce glares.
Polarized lenses are made with a synthetic plastic such as CR-39 or polycarbonate, with a polarization filter enclosed within it. The filter is made of a material whose molecules align vertically. They are good not only for anti-glare purpose but also for general trendy wear.
Authentic polarized sunglasses are more expensive than ordinary sunglasses. Many shops sell cheap polarized sunglasses that are nothing but replicas of the originals. A genuine polarized lens can be tested by rotating it in a particular direction and seeing if the glare through the lens changes in its intensity on rotation. A fake sunglass may in fact damage eyesight. It is always better (and safer) to invest a few more dollars in buying a genuine pair of polarized sunglasses rather than having the eyes suffer hazards.
Polarized sunglasses are apt for people suffering from eye disorders of long-distance vision such as hypermetropia and presbyopia, who still want to enjoy the thrills of adventure sports.
There are certain limitations associated with polarized sunglasses. People wearing polarized sunglasses may not be able to notice certain relief features on snow, as it blocks several of the light rays reflecting from it. This may be dangerous in thin ice. Another factor against polarized sunglasses is that they make LCDs almost invisible from certain angles since LCDs are also polarized light.
Due to their specialized technology, polarized sunglasses are priced higher than ordinary sunglasses. Cheaper ones are available for $75 and the price may go up to $300 depending on their brand names.
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Article Source: www.homehighlight.org
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