refraktivitetsindeks

Refraktivitetsindex, also known as the refractive index, is a dimensionless quantity that describes how light propagates through a medium. It is defined as n = c/v, where c is the speed of light in vacuum and v is the phase velocity of light in the medium. The refraktivitetsindex determines how much light is slowed and bent when entering the material, and it governs the angle of refraction according to Snell's law: n1 sin θ1 = n2 sin θ2.

Refraktivitetsindex can be wavelength dependent, a phenomenon known as dispersion. In most transparent materials, n decreases with increasing wavelength in the visible range, but the exact profile varies by material. The refraktivitetsindex is often treated as real for wavelengths with negligible absorption; in absorbing media it becomes complex, ñ = n − i k, where k is the extinction coefficient and describes attenuation of the wave inside the material.

Common reference values include air near 1.0003, water about 1.333, glass around 1.5, and diamond around 2.4 in the visible spectrum. The precise value depends on wavelength, temperature, and pressure. Refractometry uses light refraction to determine n; methods include prism dispersion, critical-angle or Abbe refractometers, and spectroscopic ellipsometry, which also yields information about dielectric functions.

Applications span optics and photonics, including lens design, fiber optics, coatings to reduce reflection or tailor color response, and numerous instrumentation fields. Knowledge of refraktivitetsindex is essential for modeling light propagation, imaging quality, and the interaction of light with materials.