Polarizers are rectangles which are defined this way:

The meaning of the parameters is the same as explained previously for rectangular light sources (where the term Vector 1 is used instead of Polarizing vector).

In ray-tracing simulations polarizers act as ideal polarizing rectangles: If a ray hits the rectangle the projection of its polarization vector into the direction of the Polarizing vector is computed. The absolute value of the projection is a number between 0 and 1. Then a random number between 0 and 1 is taken and compared to the projection. If the random number is larger the ray is absorbed. Otherwise the ray is transmitted with a polarization vector in the direction of the Polarizing vector.