About Polarised Sunglasses

Polarised sunglasses by Fuglies

Light waves travel through the air vibrating in all directions. When this light hits a shiny or transparent surface, the reflected light will vibrate be "polarised" and forced to vibrate only at an angle parallel to the surface it reflected off.

As most reflective surfaces are basically horizontal anyway (like the surface of the sea, a snow slope, or the hood of a car) the reflected vibration angle of the light is horizontal, and the physics of the reflection of the light also causes it to be more concentrated resulting in "glare".

Polarising sunglasses have a special filter layer aligned vertically so that this horizontally vibrating light is completely blocked. The horizontally vibrating light trying to get through the vertical "gates" of the polarising filter is like trying to walk through a narrow doorway while holding a long piece of timber horizontally across your body.

Light scattered by atmospheric effects like haze, falling snow, fog or rain is also forced to vibrate in only a single direction as it’s reflected off the airborne particles. But since all of the surfaces of the airborne particles are at all different angles, the reflected polarised light will be forced to vibrate at all different angles as well.

Even though only the horizontally vibrating (or polarised) light will be 100% blocked by the vertical polarising filter in the sunglasses, as the vibration direction moves further away from the vertical, the amount of blocking by the polarising filter will also increase towards 100%. Light vibrating at 45 degrees will be half blocked, while light vibrating at 30 degrees from the horizontal will be 2/3 blocked.

In this way, even though polarising sunglasses are particularly effective against the glare from light reflecting from a flat surface (since it will all be polarised near horizontally), the scattered glare from fog or snow will also be significantly reduced by as much as 60% - the horizontally polarised light will be completely blocked, the vertically polarised light not at all, but everything in between will be blocked to some degree.

Improved Visibility With Polarised Sunglasses

This reduction in scattered glare will also help to improve the visibility of distant objects in hazy or smokey conditions, making polarised sunglasses a good choice for golfers, hunters and hikers.

Unseen dust in the atmosphere will also cause glare by reflection of the sun of each dust particle, so even the anti-glare benefits of polarised sunglasses on what appears to be a clear day may be noticeable. Glare causes a reduction in contrast sensitivity so that visual acuity is reduced. Polarized lenses also enhance color saturation and depth too since many objects reflect plane polarized light.

Polarised sunglasses can also be used both indoors and outdoors by those with light-sensitive eyes, or people recovering from eye surgery like cataract surgery.

Check out the Fuglies range of polarised sunglasses...

Polarised Sun Glasses For Riding And Driving

The headlights of an oncoming vehicle contain a reflector that reflects light from the headlight lamp and concentrates it into a forward pointing beam. Once again, the act of reflecting light from a surface forces it to vibrate (or polarise) in a single direction.

The alignment of the reflected light will be anywhere from vertical to horizontal depending on the angle of the surface of the reflector at the reflection point, but the same principles apply as with scattered atmospheric glare, with polarising sunglasses effectively blocking a lot of the light coming out of an oncoming headlight.

Polarised sunglasses provide anti-glare features for all outdoor activities

Polarising sunglasses also reduce the glare that comes off a other flat surfaces such as the hood of a car or the surface of a road making driving or riding safer and more pleasureable. The sunglasses will help more with the reflections from the glass than from the metal as the former are polarised to a higher degree.

With reflections from the road surface, the direction of polarisation will change with the direction of the road with respect to the position of the sun. If the sun is in front, behind, or high above, the road reflections will tend to be horizontally polarised and the polarising filter of the sunglasses will reduce the glare.

However, if the sun is to one side, or low on the horizon the polarisation will rotate vertically, limiting the effectiveness of polarising sunglasses. If the road is wet you will get a good anti-glare result.

Check out the Fuglies range of polarised sunglasses...

Polarised Sun Glasses For Fishing And Boating

While reducing the blinding glare from reflected light is the main reason for using polarised sunglasses, the reflections coming off the surface of bodies of water also contain images of objects, clouds and scenery above the water, make it impossible to see objects below the water.

Polarised sunglasses remove the reflections from transparent surfaces

Polarising sunglasses block the reflections and hence objects below the water - like fish - become visible to the wearers of polarised sunglasses since virtually all of the reflections from the water surface are vibrating horizontally and are blocked by the vertically aligned polarising filters in the sunglasses.

As well as providing physical protection to fishermen from getting a hook in your eye, and reducing the discomfort of glare from the water (which can also be very damaging to your eyes), wearing polarised sunglasses while fishing improves below surface visibility.

This improved visibility also assists boaties in spotting underwater hazards like rocks and sand bars which would otherwise have been unseen due to the glare and reflections coming off the surface of the water.

Maximum polarisation of the surface reflections from water occur when the sun is between 30 degrees and 60 degress above the horizon. If the sun is very low or very high polarised sunglasses will not be as effective in limiting the glare from calm water.

When the sea is ruffled, the sun reflections become the familiar glitter of shimmering water stretching towards the sun. Because different parts of the glitter are reflected from different wave slopes, the angle of polarisation varies significantly.

In these conditions polarised sunglasses will also help with glare reduction for higher or lower suns angles than would be the case for calm water.

Check out the Fuglies range of polarised sunglasses...

How Can I Tell If My Sunglasses Are Polarised?

You can tell if lenses are polarised by holding them in front of you and looking at a shiny reflection. If, as you rotate the glasses like the hands of clock, the glare from the reflection disappears or is reduced, then the lenses are polarised. If nothing happens, they aren’t.

Why Are Polarised Sunglasses Better Than Normal Dark Sunglasses?

Normal sunglasses decrease the intensity of everything by the same amount. Polarised sunglasses selectively eliminate the reflected light coming from shiny surfaces, so even a clear pair of polarised glasses will reduce the glare component. Lightly tinted polarised glasses are often used as driving glasses.

Moderately tinted polarised sunglasses give you the best of both worlds - almost total glare reduction without the reduction in visibility experienced with normal tinted sunglasses that are dark enough to cut the intensity of glare as well.
Check out some of our other styles including Bi-Focal Sunglasses which are polarised as well: