Polarizing Two Filters

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March 22nd, 2009 admin Leave a comment Go to comments

Polarizing Two Filters

Glare Free - Discount Polarized Sunglasses

How many times you would have faced the situation where your eyes got troubled by the glare. Many a times! Isn’t it?

Glare is difficulty seeing anything in the presence of extreme bright light, which causes strain on the eyes but the polarized sunglasses selectively eliminate the reflection of light coming from the water surface or any other reflecting object and enable to see things clearly. The skiers, fishermen and boaters are the people who face glare the most, as most of these activities are performed in bright daylight, and do you know that too much of exposure to the glare may result in a Cataracts, which leads to running water from the eyes and later turns white and can obstruct light by causing near-sightedness (myopia). There is an easy way to prevent your eyes from Cataracts and it is to wear a pair of Polarized Sunglasses.

These sunglasses are made especially to reduce the effect of glare, and enable us to see clearly. Polarized sunglasses came into existence in 1936, this type of sunglasses contained Polaroid filter, which under a microscope look like a collection of horizontal lines. This Polaroid filter helps to cut the glare of the sun, which causes disturbance to the eyes and allow us to see things clearly. This special feature of the polarized sunglasses made it the world’s most saleable category of sunglasses and goggles as polarization is must for all type of eyewear.

How does it work?

When the reflection of the sun’s rays or any bright light hits you, it always comes in a Horizontal Angle. The filters available in polarized sunglasses cut the horizontal light waves, reducing blinding glare and its resulting eyestrain.

How to know that the sunglasses are polarized?

All you have to do to know that your sunglass are polarized or not, is to look through glasses at the reflection of any object other than your own reflection on the window panel. Then turn your sunglasses towards yourself so that it seams like the hands of the clock is facing you. If the amount of the reflection does not change with what you see through the window, then the sunglasses are not polarized.

So, next time you purchase a sunglasses then follow these guidelines, in order to not been get cheated by the seller.

Who can use it?

Being a fisherman you can use polarized sunglasses, to spot fish clearly underwater, as the Polarized lenses reduce glare of the sun bouncing off the water. The polarized sunglasses used by the fishermen has polarized filter with which the transmission axis oriented to block the light which is reflected by the water surface. Besides fishermen and boaters, people when playing sports can also use polarized sunglasses. Sports Polarized sunglasses are specifically made with light durable materials which help skiers, bikers, golfers, hikers, joggers, swimmers, and even for those who face direct sunlight while doing there day to day work.

Are they affordable?

Polarized sunglasses come in different price range, main thing to consider are the quality of lenses and materials of the frame. Polarized glasses don’t always have to look utilitarian, some models have a great combination of function and style and re inspired by designer sunglasses. If you want to afford polarized sunglasses which are good looking and have designer inspiration you have an option of Discount Polarized Sunglasses There are inspired collections of sunglasses, which are equally polarized as authentic sunglasses. This inspired collection is available in all the major brands such like D&G, Gucci, Armani and more. You see style is not an issue with an Inspired Sunglasses!

About the Author

The author is a fashion lover who loves her designer replica sunglasses . He has got the experience in writing about latest fashion trends for sunglasses and handbags. You can view his website for more information.

Physics help! Polarizing Filters & Intensity?

Please help, I'm desperate! I need assistance knowing how to do this, and how to plug in the numbers into the formula.

Two ideal polarizing filters are oriented so that they transmit the maximum amount of light when unpolarized light is shone on them.

To what fraction of its maximum value is the intensity of the transmitted light reduced when the second filter is rotated through 24.5 degrees?

To what fraction of its maximum value is the intensity of the transmitted light reduced when the second filter is rotated through 47.0 degrees?

To what fraction of its maximum value is the intensity of the transmitted light reduced when the second filter is rotated through 68.0 degrees?

When dealing with polarizers, just do one at a time, in the order that light will hit it.

When you put down the first polarizer, the intensity of unpolarized light is cut by 1/2.

When you have two polarizers in a row, the light becomes polarized after leaving the first one, so you have to use that equation of I = I_0*cos^2(theta) where theta is the angle between the polarization directions, and I_0 is the initial intensity.

ASCII art time:

I_0 ---> | I_0/2 ---> / I_0/2*cos^2(theta)

Unpolarized light is incident on a vertically polarized sheet. Its intensity is halved. Then it's incident on a polarized sheet that is tilted by some angle theta. Then it's intensity changes again by a factor of cos^2(theta).

Note that if you have a horizontal and vertical polarizer next to each other, the intensity of light is zero, because cos(90 degrees) is zero.

Also note that cos^2(theta) = 1 is a maximum, which occurs when theta = 0. In other words, if the two polarizers are oriented in the same direction, the second one won't affect the intensity at all!

Testing Polarising Filter