Polarized vs. Non-Polarized Sunglasses
November 15, 2018
They might have been developed by NASA to protect astronauts’ eyes from space radiation, but these days you’re more likely to see polarized sunglasses on a Pacific Coast sailor or angler. Not that you’d know it just by looking at them. The real wizardry takes place when you’re peeking out through the lens. Here’s how a little bit of science has made a whole lot of difference ...
What are Polarized Sunglasses?
The lenses of polarized sunglasses are coated with a thin chemical film. This film eliminates much of the harsh, brilliant light that’s reflected off water or highway surfaces on sunny days. Equipped with a pair of polarized sunglasses, wearers can see beneath the water’s surface or through sunlit windows. Standard, non-polarized sunglasses, by contrast, simply reduce the intensity of bright or shimmering reflections.
How do Polarized Sunglasses Work?
Reflective surfaces such as flat water, glass, snow, or smooth hardtops polarize natural sunlight, concentrating its waves in a single horizontal direction. This causes excessive dazzle, straining the eyes. The molecules coating polarized sunglasses are usually arranged vertically, much like blinds on a window, blocking out the piercing slices of horizontal light. These molecular ‘blinds’ let normal concentrations of the light pass but block out the intense concentrations of reflected light.
Polarized vs. Non-Polarized
Non-polarized lenses treat all sunlight equally and reduce the overall intensity. This offers protection for the eyes but will not tackle shimmer and sparkle if you’re around water, snow, or glass. Polarized sunglasses also filter ambient light but go further by canceling out bright reflected light. This advanced performance can allow:
- Anglers to see beneath the surface of a lake or river.
- Boaters to ‘read’ the texture of waves more clearly.
- Drivers to focus unhindered on the road ahead.
- Beach-goers to pick out the colors, contours, and contrasts of the sand and water better.
Both types of lenses make for more eye comfort on a sunny day, but polarized lenses actively counter the incapacitating effects of bright sunlight.
How to Tell if Lenses Are Polarized
Polarized and non-polarized lenses look the same, which is one of the reasons why you should test sunglasses labeled ‘polarized.’ To do so, look through the lenses at a reflective surface then turn the lenses 90 degrees. If the lenses are genuinely polarized, the bright reflection will appear. Alternatively, hold the lenses in front of a backlit LED screen and rotate. This time, the screen will become darker for polarized lenses, whereas non-polarized lenses will reveal no change.
Points to Consider
Although polarized lenses will tackle the discomfort caused by intense sources of light, they perform the same as non-polarized lenses when it comes to filtering out harmful UV light. If your lifestyle regularly takes you outdoors, both polarized and non-polarized sunglasses will give you essential UV protection. If you need the extra ability to see colors or contours accurately, however, polarized lenses will help.
Bear in mind that polarized lenses don’t perform as well as non-polarized when it comes to reading digital screens or displays, making them not as common among pilots. Likewise, polarized lenses make it harder to distinguish shiny patches of ice for those out walking, skiing, or driving after a snowfall, even if they do reduce overall glare.
Polarized lenses can significantly reduce eye strain, eliminate reflection, and improve performance in circumstances where the level of sunlight is overwhelming. If conditions are simply cloudy or overcast, a standard pair of non-polarized sunglasses should be sufficient to give your eyes that all-important UV protection.
Written by Nick Marshall for Knockaround