A wire grid polarizing filter is an array of parallel conducting strips or wires, where the distance between the wires must be much less than the wavelength of light you wish to work with. As long as this condition is met, light whose electric field is oriented parallel to the wires will be reflected, while light whose electric field is oriented perpendicular to it will be transmitted. In this way the polarizer may be used to either filter out undesired polarizations, select for a specific polarization, or split light into two beams with opposite polarization.
