Brewsterszögnél

Brewsterszögnél, also known as Brewster's angle, is a phenomenon in optics that describes the specific angle of incidence at which light with a particular polarization reflects perfectly off a transparent dielectric surface. This angle is named after Sir David Brewster, a Scottish physicist who discovered it in 1815. At Brewster's angle, the reflected light is entirely polarized parallel to the plane of incidence, while the refracted light is only partially polarized.

The relationship between Brewster's angle and the refractive indices of the two media is given by Brewster's law. This law states that the tangent of Brewster's angle is equal to the ratio of the refractive index of the second medium (the reflecting surface) to the refractive index of the first medium (where the light originates). Mathematically, this is expressed as tan(θ_B) = n2 / n1, where θ_B is Brewster's angle, n2 is the refractive index of the reflecting medium, and n1 is the refractive index of the incident medium.

This property has practical applications. For instance, polarizing filters used in sunglasses and camera lenses are designed to block light polarized horizontally, which is often the glare reflected from surfaces like water or roads. By aligning the polarizing axis of the filter vertically, the horizontally polarized glare is absorbed, significantly reducing visual discomfort and improving clarity. Similarly, in laser systems, Brewster windows are used at the ends of laser cavities to reduce reflection losses for light polarized parallel to the plane of incidence, thereby increasing the efficiency of the laser. The concept is fundamental to understanding reflection and polarization phenomena at interfaces between different optical materials.