So what are polarized sunglasses? How do they block both direct UV rays and reflected glare? Why can't regular sunglasses do both? When should you choose polarized sunglasses over non-polarized sunglasses? Get the answers right here.
What's the Difference between Polarized and Non-Polarized Sunglasses?
Non-polarized sunglasses work by blocking harmful UV rays, but without a special polarized filter in the lens, they aren't equipped to block the reflected light (glare) from smooth surfaces like water, snow, pavement, car windshields and sand. Polarized sunglasses, however, cut through that reflective glare to increase clarity and decrease discomfort. So what's the difference between polarized and non-polarized lenses? The answers lie in the physics of the wave-like behavior of light. So let's dive right in, shall we?
Polarization and the Physics of Light Waves
Understanding how a light wave moves is key to understanding how polarized sunglasses work. A light wave is an electromagnetic wave that is created by vibrating electric charges. Light waves are "transverse waves," which means that the particles of the wave move perpendicular to the direction in which the wave is moving. Imagine the waves in the ocean or a ripple in a pond -- these are both examples of transverse waves.
The glare that polarized lenses combat is the result of light waves that have undergone what's not surprisingly called "polarization." Polarization of light happens when the up-and-down oscillation of light waves reflect off of non-metallic surfaces, like water, and oscillate in a back-and-forth motion after being reflected. This change in oscillation direction is what causes the glare that you see when you aren't wearing polarized sunglasses.
How Do Polarized Lenses Block Glare?
What polarized lenses do is utilize a filter with a vertically-oriented transmission axis to allow the unpolarized light waves that are oscillating up-and-down through, but not the polarized, glare-creating light waves that are oscillating back-and-forth. Some describe the molecular structure of a polarized lens filter like a fence or shutter, which structurally can only allow the vertical movement of unpolarized light through. The back-and-forth movement of polarized, glare-causing light gets stuck at the "fence" of the filter, so glare is greatly reduced.
Polarized Sunglasses vs. Non-Polarized Sunglasses: How to choose
Anyone who spends time on the road, water, sand or snow will benefit from a nice pair of polarized sunglasses. The glare-cutting performance of polarized sunglasses is a must for anglers because the glare off of water not only makes it difficult to spot fish, but can cause uncomfortable eye strain. Road cyclists prefer polarized sunglasses because obstacles like potholes are easier to spot when you're not squinting against the glare of the pavement. And golfers like polarized sunglasses because they cut through the glare of sand traps and water hazards.
However, you may not want polarized sunglasses if you often use an LCD or LED display. Pilots, for instance, may have difficulty reading LCD displays on instrument panels if they're wearing polarized sunglasses. And some find it hard to use their cell phone when they are wearing polarized lenses. Most of the time, though, it's worth it to enjoy the glare-cutting performance of polarized sunglasses.
Want more details about all of your sunglasses options? Check out the Sierra Trading Post sunglasses guide.