Planepolarizers

Planepolarizers are optical devices that transmit light with its electric field oscillating in a specific plane while absorbing light polarized perpendicular to that plane. This selective transmission is achieved through the use of polarizing materials, which can be either dichroic or birefringent. Dichroic polarizers, such as those found in polarized sunglasses, contain long-chain molecules aligned in a particular direction. When light passes through, these molecules absorb photons whose electric fields are parallel to their alignment. Birefringent polarizers, on the other hand, utilize materials that exhibit different refractive indices for light polarized along different axes, effectively splitting the light into two polarized beams and allowing one to be discarded.

The primary function of a planepolarizer is to control the polarization state of light. This is crucial in a variety of applications. In photography, polarizers are used to reduce glare from reflective surfaces like water and glass, and to enhance color saturation. In scientific instruments, they are essential for measuring the polarization of light, which can reveal information about the material properties or interactions of light with matter. Liquid crystal displays (LCDs) rely heavily on polarizers to control the passage of light and create images. They are also used in 3D movie systems, stress analysis of materials, and in various optical experiments. The effectiveness of a polarizer is often measured by its extinction ratio, which indicates how well it blocks light polarized perpendicular to its transmission axis.