Polarisaationa

Polarisaationa is the property of transverse waves that describes the orientation of their oscillations, most commonly applied to electromagnetic radiation such as visible light. In light, polarization refers to the direction of the electric field vector as the wave propagates. A light beam can be unpolarised, with oscillations in many planes, or polarised, with a preferred orientation.

Common forms of polarisation include linear, circular, and elliptical. Linear polarisation has the electric field oscillating in a single plane. Circular polarisation features the electric field rotating at a constant magnitude, producing right- or left-handed helicity. Elliptical polarisation generalises these cases, with the tip of the electric field tracing an ellipse. Polarisation can be described quantitatively by formalisms such as the Stokes parameters or the Jones calculus, and visualised on the Poincaré sphere.

Polarisation is produced or modified in several ways. Polarising filters selectively transmit certain orientations. Reflection and refraction at interfaces, especially at non-normal incidence, can induce polarization through Fresnel effects. Birefringent crystals and wave plates alter the phase between orthogonal components, converting linear to circular or elliptical states. Scattering, particularly Rayleigh scattering in the atmosphere, naturally polarises skylight.

Measurement and analysis of polarisation use devices such as polarizers and analyzers, and concepts like the degree of polarisation and polarization angle. More advanced descriptions employ Stokes parameters, Jones calculus, or the Poincaré sphere.

Applications of polarisation are widespread, including photography and cinematography with polarising filters, liquid-crystal displays, and optical communications using polarization multiplexing. Polarimetry is used in astronomy, remote sensing, and material science, notably in stress analysis through photoelasticity. Polarisaationa thus underpins both fundamental physics and practical technologies.