Natriumspiegel

Natriumspiegel is a term that translates to "sodium mirror" in German. It is not a widely standardized term in physics, and there is no entry that defines it uniformly in major reference works. In practice, the phrase may be used in different contexts to describe an optical element, a calibration target, or a phenomenon involving sodium-bearing materials or emission.

In optics and spectroscopy, Natriumspiegel can refer to either a mirror surface or coating designed to have particular reflectivity near wavelengths associated with sodium, notably the D-line around 589 nanometers; or a reflective setup that uses sodium vapor or sodium fluorescence as a reference. Such designs can support wavelength calibration, spectral filtering, or experimental alignment in laboratory contexts, depending on how the term is employed by the author.

In astronomy and atmospheric science, related ideas include the sodium layer in the mesosphere and sodium laser guide stars, which exploit sodium atoms to create artificial reference points for adaptive optics. Although not a standard device named "Natriumspiegel," these concepts share a common theme of leveraging sodium’s optical properties for measurement or calibration purposes.

Usage of the term remains largely contextual and may appear in technical notes, lectures, or German-language articles without a fixed definition. For precise interpretation, it is best to consult the specific source where the term is used, or to rely on standard terminology such as optical coatings, reflectivity, or sodium D-line calibration.