The Science Behind Polarization

Light waves from the sun, or other artificial light such as a light bulb, vibrate and radiate outward in all directions. Polarized filters are most commonly made of a chemical film applied to a transparent plastic or glass surface. The chemical compound used will typically be composed of molecules that naturally align in parallel relation to one another. When applied uniformly to the lens, the molecules create a microscopic filter that absorbs any light matching their alignment.

When light strikes a surface, the reflected waves are polarized to match the angle of that surface. So, a highly reflective horizontal surface, such as a lake, will produce a lot of horizontally polarized light which causes a very intense and sometimes dangerous brightness that results in glare and reduces visibility. Therefore, the polarized lenses in sunglasses are fixed at an angle that only allows vertically polarized light to enter. The horizontal light that creates the effect of glare is absorbed and nullified by the chemical film on polarized lenses.

The first polarizing film was developed by Edward H. Land in 1929. The technology he used as explained above was simple, yet effective. Lenses are treated with chemicals that only allow in light that travels in a vertical motion. As glare travels horizontally, it can’t make it past the polarized lens.

How To Test If Your Sunglasses Are Polarized

Polarized sunglasses do not look very different from regular non-polarized ones. As a matter of fact, some companies that produce lower-quality sunglasses market them as polarized when they are not. So you need to have a way to tell the difference. Here are some ways to determine if your sunglasses are polarized or not:

  1. Checking the label or sticker: Obviously, the simplest way to know if your sunglasses are polarized is to check the product description (if you bought online), the tag attached to the glasses or box they came in, and the sticker on the glasses. Since most people consider polarized sunglasses are somewhat superior to regular ones, the manufacturers would most likely include this advantageous feature in order to get their products to sell faster. If it doesn’t state on the sticker, the box or the product listing online that it is polarized, then it most likely isn’t. Bear in mind though, that not all companies are genuine in stating the real contents of their products, so this might not be the most effective method to affirm the polarization of your sunglasses. However, if the company is a reputable one that you trust, you can take their word for it.
  2. Comparing two pairs: Another way to determine the polarization of your sunglasses is by comparing it with a pair that you know for sure is polarized. This can be a pair that you borrowed from a friend, an old pair you have at home or a polarized pair off the shelf in a store. When you hold both pairs of sunglasses up, one in front of the other, you should be able to see through them. However, if you tilt or rotate one of the pairs to a 90 degrees angle, the lens should darken or black out if they are both polarized. If it is clear when rotated and you can see the polarized pair behind the pair in question, then the new pair is not polarized.
  3. Looking at water or reflective surfaces: To determine whether your sunglasses are polarized or not, simply put on your sunglasses and find a surface that light bounces off of. This could be a shiny flat reflective surface like car windshield or windows or glass tabletops and it could be a shallow body of water like a lake or river in broad daylight. You’ll know your sunglasses are polarized if you can see past the glare on the particular surface you’re looking at or if you can see right into the body of water below. If you can’t, you have just a regular tinted pair of sunglasses.
  4. Looking at a computer or LCD screen: For best results, try to make the screen as white as possible. If you’re using your computer, pull up a blank MS word document and if you’re using your mobile device for the experiment, try Google’s homepage. To use this method, just put on your sunglasses or hold it up against the screen. Then tilt your head or the sunglasses at a 60-degree angle and if the screen dims or darkens, you have polarized sunglasses. The science behind this is that most computer screens have the same anti-glare protection as polarized sunglasses do. As a result, the lens and screen end up counteracting each other by working in opposite directions and you’ll get a dark or blacked-out image on the screen.
  5. Using test cards: Another unconventional way to test for polarized sunglasses is by using polarization test cards. A lot of companies that sell polarized sunglasses also sell these test cards. When the cards are viewed through a polarized lens, an image will appear on the card. Meanwhile, if they’re viewed with regular sunglasses, they’ll appear blank.  

Everyone should own a pair of polarized sunglasses. They are the premier choice for outdoor enthusiasts, and those who live their lives on the water- fishing, boating etc and anyone else who demands the clearest vision from their sunglasses. The reason they’re in such high demand is mainly because of their glare-reducing benefits. Regular tinted sunglasses do not block glare, so make sure you don’t waste your precious coins on them. Using the guide in this article when next time you want to purchase sunglasses will ensure you buy genuinely polarized ones, and get good value for your money.