- The straight lines in each polarizer indicate the transmission axis of that piece.
- Polarizer is a device which transmits only
the component of polariztion parallel to its transmission axis. By using
a polarizer, the plane of a plane-polarized wave can be changed; a circularly
polarized or unpolarized light can be changed to plane-polarized.
- When a circularly or unpolarized wave is incident
on a polarizer of whatever the orientation of transmission axis, the wave
intensity passing through is always one-half of the incident one (after
averaging over many random changes in the case of unpolarized wave).
- No wave can pass through two polarizers whose
transmission axes are crossed perpendicularly. However,when a third polarizer
is inserted between them with an angle not parallel to either of them, some
wave can finally pass through.
- Malus' law: The intensity (proportional to
the square of amplitude) of the wave passing through a polarizer (I) is
the intensity of the incident plane-polarized wave (Io) times the square
of the cosine of the angle between the transmission axis of the polarizer
and the incident polariztion (θ), i.e., I = Iocos2θ