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Sunglasses: a very brief history
In the beginning sunglasses weren’t always used to protect peoples eyes from the sun. The history dates back to ancient China and Rome. It has been reported that the Roman Emperor Nero enjoyed watching gladiators through polished gems. In China, sunglasses were used before the 12th century. Sunglasses were first made out of lenses that were made from flat panes of smoky quartz. Chinese judges used such glasses to hide their facial expressions when interrogating witnesses.
Sunglasses didn’t undergo any further changes until about the eighteenth century with the work of James Ayscough. He experimented with tinted lenses in spectacles. Sunglasses then went the change into the popular item they are today when Sam Foster introduced them to America in 1929. These sunglasses were designed to protect people’s eyes from the sun. In 1936 sunglasses became polarized when Edwin Land began using his panted Polaroid filter when making sunglasses. From this original process comes what we now as polarized sun glasses. They have come a long way from their Roman and Chinese roots.
Why wear polarized sun glasses?
When the sun shines on the water or any other reflective surface, the reflected light becomes polarized. This means that most, although not all of the light waves move in one plane. You see, normal light moves in many planes and polarized lenses allow only light in one plane to pass through the lens. Therefore much of the glare is eliminated.
Although light from the sun is not polarized, it can be separated into two polarized components that are reflected and transmitted in different amounts by the surface of the water. In most cases more of the horizontal component will be reflected than the vertical component, thus partially polarizing the reflected light. In order to help eliminate the glare a lens that is vertically polarized is used. The height of the sun also affects the degree of polarization. Basically, the polarized sun glasses worn by fishermen have polarized filters to help block the light reflected by the waters surface allowing them to be able to see under the waters surface.
Will polarized sun glasses eliminate all reflected light?
Absolutely not. As we said before, polarized sun glasses eliminate selective parts of the reflected light, thus reducing glare.
Why wear polarized sun glasses when fishing?
Certain surfaces, such as water, can reflect a lot of light, and the resulting bright spots can be quite distracting and even hide objects (such as fish). A good pair of sunglasses can almost completely eliminate this kind of glare using polarization. Polarization can occur either naturally or artificially. An example of natural polarization can be seen any time you look at a lake or river. The reflected glare off of the surface of the water is the light that doesn’t make it through the “filter” of the water, and is the reason you often cannot see anything below the surface, even if the water is crystal clear.
When light strikes the surface of the water a lot of horizontally polarized light is the result. Therefore you can’t see anything but the glare on the water. Polarized lenses in sun glasses are fixed at an angler that only allows vertically polarized light to enter allowing the angler to see into the water spotting fish and structure.
What’s the difference between polarized sun glasses and normal sun glasses?
Basically, normal sun glasses decrease the intensity of all light that passes through the lenses. Polarized sun glasses decrease the same light, but they do it selectively. Polarized sun glasses can selectively eliminate the reflection from the light coming from the waters surface.[ad_2]
write by Donald Prince