Polarized vs Non-Polarized sunglasses

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I’ve had like 12 people explain this to me and have absolutely no idea what polarized glasses are or why they’re so special.

In: Engineering

16 Answers

Anonymous 0 Comments

There is a coating that prevents glare from sun hitting your eyes.

The glare obscures details you could otherwise see, the image is there but hidden by glare. So once the glare is removed you can see the things.

Anonymous 0 Comments

There are tiny slits in them, all parallel, that block some light rays coming from certain directions. When the light is coming all from one direction, like with glare from the sun reflecting off of something, it will block some of it. That’s how they reduce glare. Only scattered light rays, which is most light, gets through. They are called polarized because the slits all go in the same direction, aiming toward “poles.”
They work like eskimo snow goggles that block the bright light reflecting off of snow–you see less light when it comes from a certain direction. They have thousands of tiny slits instead of one big one.
[https://en.wikipedia.org/wiki/Snow_goggles](https://en.wikipedia.org/wiki/Snow_goggles)

Anonymous 0 Comments

Think of lenses like thousands of hoses bundled together. The light passing through them is like water. Natural light comes towards the hoses and is choppy. It comes in from all angles and causes inconsistent pressure in the hoses leading to a very rough flow on the other side. Polarization is placing a bunch of slats in front on the hoses. Suddenly the only water coming in is the water lined up with the slats. Everything else is blocked and redirected by those slats. So now when the water flows into the hose it is a nice smooth steady flow and comes out of the other side as a constant crystal clear flow.

In the case of light we are selectively removing certain kinds of photons that would interfere with each other and form glare. polarization keeps all that light coming into your eyes nice and smooth and lined up which increases clarity of vision. It’s why polarized lenses also help you see through the surface of water as the polarization helps eliminate the scattered light and let’s you see the light reflected off the deeper parts of the water.

Anonymous 0 Comments

Think of light as a wave, like sound waves or radio waves.

Those waves bounce off of surfaces and reflect at new angles. A good example is if you speak loudly in a bare room with lots of hard surfaces – you hear distorted echos of your own voice, those are sound waves reflecting back at different angles and timing.

Light does the same. Some surfaces reflect light back at different angles creating what we call glare.

Polarized sunglasses have a filter which stops that light which is reflected from different angles, so you don’t see the glare.

They’re the equivalent of taking that bare room and putting in a thick rug and various pieces of furniture so that when you speak those echos are now absorbed.

Anonymous 0 Comments

Rays of light actually have an orientation: they can be upright, twisted to one side, etc.

Polarized glasses filter out light oriented at a particular angle, which is the angle that glare from the sun usually reaches you with.

You can tell they’re really polarized because if you take them off your face and rotate them, suddenly the glare will come through again. If you put two of them up and rotate them just right, they’ll block all the light.

Anonymous 0 Comments

Light from the sun is unpolarized. When it reflects off of horizontal surfaces it becomes polarized, meaning that all the light waves are oscillating in the same plane. That part is important, but probably beyond the scope of ELI5.

Because the light is polarized, you can use a special filter in the form of a coating to reduce the amount of reflected light that comes through your sunglasses. This is called a polarizing filter, and these types of sunglasses are referred to as “polarized sunglasses”.

Non-polarized sunglasses reduce the amount of light coming through them, but they do it by blocking a percentage of *all* light via tinting. Tinting has a tradeoff in that it reduces brightness but also makes it harder to see as you increase the amount of tint.

Polarized sunglasses can reduce the amount of ambient light by using tint, and then further reduce *specifically* reflected light (glare) by using the polarizing filter. This allows you to use less tint since you’re able to target only the brightest reflection sources with the polarizing filter, which allows clearer vision overall.

Anonymous 0 Comments

If you want to be able to read a phone screen with your sunglasses on avoid polarized glasses. You have to hold your phone at a very specific angle to see it at all.

Anonymous 0 Comments

I’ll take a try at this from my understanding, basically polarized sunglasses use a filter that blocks out certain polarizations of light. An easy example is saying each polarization of light has a shape. Light changes it’s polarization or “shape” when it bounces off things. The sunglasses have microscopic slits that filter out any shape they don’t want through. So you want to let through sun light for example, but not the glare off of the surface of a lake.

This also is evident in most video screens these days have a polarizing filter on them to keep the light organized into the “shape” it wants. So when you look at a screen with polarized sunglasses, it compounds the filtering and gives you the rainbow colors or total loss of image from your cell phone screen for example. You can test this by looking at a screen with polarized glasses, and turn your head or the screen 90 degrees and see how the effect changes as you change the orientation of the light coming from the screen to your eyes.

Anonymous 0 Comments

I was a physics major and I still don’t really understand the polarization of light. My brother (also a physics major) and I tried to get a grasp on it one day together, but we couldn’t get to the “like I’m 5” level. Only the trust-in-calculus level.

There are better answers here than mine, I just want to confirm that this is not an easy question to answer without major oversimplification.

Anonymous 0 Comments

Light is made up of photon, and the oscilate in a certain direction. Literally any angle perpendicular to the way they travel.

When you have a normal stream of light, there are so many photons that the light is basically oscillating in all directions.

If we put a polarizing filter in the way of the light, only light that is aligned with the filter can get through.

Sun glasses are usually polarized vertically (up and down) because horizontal light is more likely to scatter when hitting a surface, especially water, causing a glare. If you turn your head sideways while looking through polarized sunglasses, you’ll notice they don’t work as well.

3D glasses are also polarized, one horizontal and one vertical, so the projector can output two images on the screen using horizontal and vertical light, the glasses filter out the alternate image, and your brain constructs a 3D image from the information reaching your brain.

If you have two pairs of polarized sun glasses, and turn one 90° from the other, no light can get through and the second pair of glasses will appear black, because no light can pass through both filters.

Similarly, with 3D glasses, if you put them on and close one eye, another pair of 3D glasses will have the other lens blacked out for the same reason