1. Polarization

2. Polarization
When light (or any other electromagnetic wave) travels through space, it vibrates in multiple dimensions simultaneously).
When any electromagnetic waves passes through a filter, the filter eliminates vibrations in all dimensions except one.

3. Polarization
We call the wave, or radiation that passes through a filter as polarized, because it vibrates in only one dimension.
Before the light passes through a filter, we call it unpolarized, because it vibrates in every dimension.

4. Polarization
As you can see from the previous slide, placing vertical and horizontal filters back-to-back has the effect of cancelling out radiation, such as light, altogether
The is the basic technology beyond polarized sunglasses, for example.