Polarised sunglasses: See further with high-tech eyewear
Polarised sunglasses are a smart addition to your eyewear any time you’re venturing out on the water, the slopes or anywhere else with bright glare. To appreciate the benefits of we first need to understand exactly what the polarisation of light means.
What is polarisation of light?
Polarised light is produced when light is reflected off horizontal surfaces like roads, water or snow. By wearing lenses with a vertically oriented filter we can keep these lights from affecting our vision – in simpler terms, the filter allows only the vertical light to pass through it. Your eyes are shielded from annoying glare when the horizontal light comes through. This provides a better visual, compared with standard tinted sunglasses.
What can polarised sunglasses do for you?
Polarised shades help reduce the flash created by the sun when it hits the water; they eliminate this glare and enable you to see into the water. This is of great use for anyone who wants to fish. These polarized glasses selectively reduce the reflections of other things above the water, like the sky or the clouds – in fact, the reflected sky is what gives most of the blue color to the sea. The light that comes from underwater, that you want to see, is always somewhat polarised in the vertical plane (it gets polarised on transmission). The outcome is that the water appears darker but more transparent! It only works when you look at the water at an angle and not straight down.
If the sea is rough then the reflection of the sun becomes the familiar glitter – you’ve probably seen what looks like an elongated pattern of glistening water reaching towards the sun. As the various facets of the gleam are reflected from many different wave slopes, the degree of polarisation changes from place to place. In these circumstances, the sunglasses will also help, and the benefit will mainly depend on the angle you look from.
The polarised sunglasses used by fishermen contain polar filters and their transmission axis is oriented vertically, so that light reflected by the horizontal surface of the water is blocked.
How do you know if glasses are polarised?
If you want to know if a pair of glasses is polarised, hold them in your hands and look through them at any reflection of an object in a window pane (you’ll need to look at an angle so that you do not look at yourself). Next, turn the sunglasses clockwise while looking through the lenses. If they’re polarised, you’ll notice a change in the intensity of the image you see through the window as the reflection on the window’s surface is reduced. If the intensity does not change, the glasses are not polarised.
When you wear normal sunglasses, the intensity of everything you see is decreased by the same amount, whereas polarised sunglasses selectively eliminate the reflection of light interfering with what you want to see. Technically speaking, polarised glasses decrease the intensity of horizontally reflected light by at least half, making fishing easier and improving visibility for anyone who wants to reduce everyday glare and see freely.
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