What is light that has passed through a polarizing filter called?

A light that has passed through a polarizing filter is called polarized light. Polarized light contains electromagnetic waves that oscillate in one direction, in nonpolarized light the waves oscillate in different directions. The filter that causes the polarization is called a polarizer.

There are four main methods used to polarize light: reflection, scattering, transmission and refraction. The most common method, transmission, is the method which uses a polarizing filter. The filters contain special material that can block all but one of the waves oscillating directions. An example of a polarizing filter is the natural crystal CaCO₃. Polarizing filters can be used in front of a camera lens to reduce glare and manage reflections when taking a photograph.