planepolarizer

A planepolarizer, often shortened to polarizer, is an optical filter that transmits light of a specific polarization parallel to its transmission axis and blocks light of other polarizations. Unpolarized light, which consists of electromagnetic waves vibrating in all directions perpendicular to its direction of propagation, becomes linearly polarized after passing through a polarizer. This means the light waves will then vibrate primarily in a single plane.

The principle behind a planepolarizer is the selective absorption or reflection of light based on its polarization state. Early polarizers, like the Polaroid Corporation's HN-50 and HN-72 films, utilized dichroism, where certain molecules within the material preferentially absorb light polarized in a specific direction. More modern polarizers, such as wire-grid polarizers, consist of a series of parallel conductive wires. Light polarized parallel to the wires induces currents in them, which dissipate the energy as heat, effectively blocking that polarization. Light polarized perpendicular to the wires passes through with minimal attenuation.

Planepolarizers find widespread applications in various fields. In photography, they are used to reduce glare and enhance color saturation. In liquid crystal displays (LCDs), polarizers are essential components that control the passage of light to create images. They are also used in scientific instruments for measuring optical activity, analyzing stress in materials, and in sunglasses to reduce reflections from horizontal surfaces like water and roads. The orientation of the transmission axis relative to the incoming light determines the amount of light transmitted.