The term “polarized” is thrown around quite frequently in sunglasses stores and among sunglass enthusiasts. I’m you’ve always wondered what it means for a pair of sunglasses to be polarized, but you’ve been too afraid to ask—you’re not alone. Although many people know what polarized sunglasses do, few understand how they work. But, after reading this article, you’ll be able to speak on the topic like a pro.
What on earth is Polarization?
Light has a property associated with its direction of vibration called “polarization”—you can think of vertically polarized light as waves oscillating up and down and horizontally polarized light as waves oscillating left and right. Light waves can also oscillate in any other direction.
But, light from most sources has numerous individual light waves, all oscillating in arbitrary directions. You can think of ordinary light as having 50% horizontally polarized waves and 50% vertically polarized waves. These two polarizations nicely cancel each other, leaving us with light with no polarization, aka “unpolarized light.
But when light is reflected off of a surface (such as the roof of a car or the surface of the water at a beach), it gets slightly polarized in the direction of that surface. This means that in reflected light from a “glare,” there is a lot more horizontally polarized light than vertically polarized light. The balance is no longer 50/50. Such light is called “partially polarized light.”
Okay, But What do Polarized Sunglasses do?
Thought you’d never ask. On the lenses of polarized sunglasses, there’s a nanomaterial layer that only allows vertically polarized light to pass while blocking all horizontally polarized light. This layer is (quite conveniently) called a “polarizer.”
When ordinary light passes through a vertically polarized lens, all of its horizontally polarized light gets blocked, leaving only the vertically polarized light. The result? Since 50% of ordinary light is horizontally polarized, removing horizontally polarized light reduces the intensity of ordinary light by about 50%, making everything darker. This is no different from an ordinary pair of sunglasses.
But partially polarized light is composed of more horizontally polarized light than vertically polarized light. Let’s say, for example, a beam of partially polarized light had 70% horizontally polarized light and 30% vertically polarized light. When this partially polarized light passes through a polarized lens, all of its horizontal constituents will be blocked, resulting in a reduction of 70%.
And What Does That Mean for Me?
This means that when you look around wearing polarized sunglasses, a lot of the light coming from glares is blocked, improving visibility.
If you enjoy sports and other outdoor activities, wearing a pair of Bonfire riding shades with vertical polarization and UV400 can improve your performance, reduce the risk of injury and keep you protected.
