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How Polarized Lenses Work

by John M. White |

Protecting Your Eyes

Before we can discuss how polarized lenses work we first need to understand what lenses themselves are, and then how polarization relates to their functioning. For our purposes we need to discuss two types of lenses, the anatomical (human) lens and the physical (glasses) lens. The reason it is important to understand how polarized lenses work is because they can either be a benefit for the wearer, or alternatively, they could create problems for the wearers. As an example, fishermen really like polarized lenses because they allow them to look past the glare on the water’s surface and see the fish in the water. On the other hand, being able to see the glare from the sun’s rays reflecting off of the surface of another aircraft is a benefit to pilots, particularly to fighter pilots who rely upon their eyes to see opposing fighter aircraft before the other pilot sees them. This is one reason why pilots prefer Randolph Aviator sunglasses to any others. Randolph Aviator glasses The human eye has a lens which refracts the light entering the eye so that it can be focused on the retina at the back of the eye. The lens in the human eye is also known as the aquula, or crystalline lens, and is made up mainly of water. This lens has the refractive power of approximately 18 dioptres (the reciprocal of the focal length of the lens measured in meters), or roughly one-third of the eye’s total power. The lens in your eye changes shape which in turn changes the focal distance of the eye so that it can clearly define objects at various distances. In other words, it allows the human eye to see clearly objects that are both near and far away from the viewer at the same time, allowing a sharp image of the objects of interest to be formed on the eye’s retina. Light from the objects of interest enter the eye perpendicular (or horizontal) to the surface of the earth. Randolph Aviator Polarized lenses have a laminated surface which contains vertical stripes which allows only vertically polarized light to enter the eyes. This means that light which is reflected off of metal, glass or smooth surfaces will not be able to enter the eyes, thereby eliminating glare from the sun’s rays striking those surfaces. However, polarized lenses do not provide complete protection from glare because if you tilt your head more than 45 degrees from the vertical some of the horizontally polarized light will still pass through the polarized lens and enter your eyes. Another effect of polarized lenses is that they lose some of their ability to see the contrast between bright and dark areas, making them less useful in certain conditions. For example, when skiing on snow, polarized lenses will make it more difficult for the skier to see the contrast between snow and shadows as they ski. Fishermen and drivers of cars, on the other hand, find polarized lenses to be more useful because they are dealing with mainly light reflected from horizontal surfaces, eliminating much of the glare from the sun’s rays striking objects along the driver’s path. For pilots, the opposite is true. Pilots need to be able to see clearly, and the reflection of light from metallic and glass surfaces can help them spot an aircraft on a converging course quicker, allowing them to adjust their flight path to avoid the other airplane. This is the reason original aviator sunglasses were developed for pilots, and why pilots around the world prefer them to any others. In addition, these sunglasses have bayonet style temples which slip easily into a helmet or headset the pilot is wearing. Randolph Engineering Aviator sunglasses have been the choice for military pilots around the world, and each time a space shuttle launches the astronauts are wearing Randolph Aviators. Until next time keep your wings straight and level Hersch! JetAviator7 If God had meant man to fly, He would never have given us the steam railway locomotive. — A Great Aviation Quotes reader's late great aunt.

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