Why Sunglasses Turn Your Phone Screen Blank

Blonde girl using her smartphone

You’re sitting on the deck with a cold drink and nothing to do but watch the world go by. Suddenly, you hear the telltale sound of a text message arriving on your phone. You dutifully attempt to read the message to discover that you can’t see it through your sunglasses. The sunglasses have effectively blanked the screen. So what gives?

Not being able to read a mobile screen while wearing sunglasses is a fairly common problem. This article will explain the science behind it for those who are interested. At the end of the article is a fairly easy solution. You can decide for yourself how much you want to read. With that out of the way, let us get on to the science.

How Light Travels

Buzzing all around us, in nearly every corner of the universe, is something known as the electromagnetic spectrum. What we understand as light is electromagnetic radiation that takes up just a portion of that spectrum. What constitutes visible light to the human eye is yet a smaller part of that spectrum.

As explained by Popular Science magazine, light travels in waves as groups of photons that move in multiple directions at once. This multi-directional travel is that which makes it possible to light an entire room just by turning on a single lamp. The fact is that visible light is unidirectional unless something intervenes to limit that direction. Now, here’s where it gets interesting.

Imagine a mishmash of unidirectional light photons hitting the surface of a lake. As the light is reflected, it suddenly organizes into waves to travel in just two directions: vertically and horizontally. The waves are concentrated for all intents and purposes. This concentration is what causes sun glare. It can be the result of light reflecting off water, snow, pavement, a car hood, or any other surface.

The Polarizing Effect

Now that you know how light travels, the next thing to understand is the polarizing effect you observe when wearing polarized sunglasses. This effect is explained nicely by Olympic Eyewear, a Utah company that designs and distributes more than a dozen designer brands.

Olympic Eyewear explains that polarized sunglasses have special lenses with built-in filters. Those filters filter out the concentrated light waves moving in one direction, usually horizontally. The waves moving vertically still pass through. By filtering out just one direction, polarized sunglasses eliminate glare so that you can see. Now, let’s apply this to our mobile devices.

Polarized Mobile Screens

Screens on modern mobile devices are polarized as well. This is done in order to filter the visible light so that you can see your screen under multiple conditions. The problem comes to bear when your sunglasses and screen filter light running in opposite directions.

Let’s say your sunglasses filter out horizontal waves while your screen filters out vertical waves. You will not be able to see your screen as long as you’re wearing your sunglasses. If both your sunglasses and mobile device screen filter in the same direction everything is fine.

As for the easy solution, there are actually two of them. The first is to just take off your sunglasses temporarily. Read the text message and then put them back on. The other solution is so simple you will not believe it when you hear it: rotate the screen by 90 degrees. The polarization is built into the screen itself, so rotating the device will align the screen with your sunglasses.

Thanks to Popular Science and Olympic Eyewear, you now you know why you can’t see your phone screen while wearing your sunglasses. Fascinating, isn’t it?

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