Polarized light.

A polarizer was invented by Francois Arago in 1812 but wasn’t used commercially until 1932 by Dr. Edwin Land in Polaroid cameras. Light travels in waves, when it reflects off of a surface it reflects in all different directions. This is what we call glare and a polarizer only allows one orientation of light through the polarized filter.

Polarized sunglasses only allow in one orientation of light which decreases glare and improves contrast when viewing through the sunglasses.

Right shows glare from the sun and decreased contrast of the environment. Left shows decreased glare and increased contrast of the environment due to the use of a polarized filter.

Polarization is also used in 3D glasses or screens in our cars or devices. For 3D glasses one eye gets one polarized image and the other eye gets another giving the 3D effect to your image or movie. If you have ever noticed while looking at your phone with sunglasses it is darker or completely black it is because the polarized light that the screen is giving off does not match the orientation of the polarized filter in the sunglasses. Try this next time when you look at your phone with sunglasses on to see if your sunglasses are polarized!