upolarisert

Upolarisert, known in English as unpolarized, describes light that has no fixed polarization direction when averaged over time or space. In such light, the polarization state varies randomly, so the net polarization is zero (the degree of polarization is zero).

Most natural light sources are effectively upolarisert; incandescent bulbs, the sun, and many artificial sources emit a mixture of polarization states. Polarization can become biased in certain conditions, yielding partially polarised light (0 < P ≤ 1). In practice, no real light source is perfectly unpolarized, but many are treated as such for purposes of measurement and analysis.

In optical measurements, unpolarized light is conveniently described by Stokes parameters. For a completely unpolarized beam, I > 0 while Q = U = V = 0, and the degree of polarization P = 0. When such light passes through an ideal linear polarizer, the transmitted intensity is halved on average, and the output becomes linearly polarized. In real systems, deviations from ideal behavior are common, and the result depends on the specific source and optical components.

Applications and considerations: unpolarized light serves as a baseline in polarization experiments and imaging. Polarizers and wave plates are used to convert unpolarized light into desired polarized states for analysis or illumination. Related concepts include polarization, polarizers, Stokes parameters, degree of polarization, and partial polarization.