A dye laser used at the Starfire Optical Range for LIDAR and laser guide star experiments is tuned to the sodium D line and used to excite sodium atoms in the upper atmosphere.

Sodium layer refers to a layer within the Earth's mesosphere of unbound, non-ionized atoms of sodium. The altitude of this layer is usually located between 80–105 km (50–65 miles) and has a depth of about 5 km (3 miles). Atmospheric sodium below this layer is normally chemically-bound in compounds such as sodium oxide, while above the layer the atoms tend to be ionized. Image File history File linksMetadata Download high resolution version (2000x3008, 4406 KB) Original caption: Though the caption states that this is a sodium laser, this is actually misleading as the lasing medium in the Starfire Optical Range LIDAR laser seen here is really a dye laser which is tuned to... Image File history File linksMetadata Download high resolution version (2000x3008, 4406 KB) Original caption: Though the caption states that this is a sodium laser, this is actually misleading as the lasing medium in the Starfire Optical Range LIDAR laser seen here is really a dye laser which is tuned to... A dye laser is a laser that uses an organic dye as a lasing medium, usually as a liquid solution. ... LIDAR (Light Detection and Ranging; or Laser Imaging Detection and Ranging) is a technology that determines distance to an object or surface using laser pulses. ... Lick Observatory laser guide star, built by LLNL. Laser guide stars are a form of artificial star created for use in astronomical adaptive optics imaging. ... Solar Fraunhofer lines In physics and optics, the Fraunhofer lines are a set of spectral lines named for the German physicist Joseph von Fraunhofer (1787--1826). ... Earth is the third planet in the solar system. ... The mesosphere (from the Greek words mesos = middle and sphaira = ball) is the layer of the Earths atmosphere that is directly above the stratosphere and directly below the thermosphere. ... // An ion is an atom, group of atoms, or subatomic particle with a net electric charge. ... Properties In chemistry and physics, an atom (Greek άτομον meaning indivisible) is the smallest possible particle of a chemical element that retains its chemical properties. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... Basic Information Flash point Non flammable Supplementary data page Structure and properties n, εr, etc. ...

Atoms of sodium in this layer are typically in an excited state, and radiate weakly at a wavelengths around 589 nm, which is in the yellow portion of the spectrum. These radiation bands are known as the sodium D lines. The resulting radiation has been termed night glow. Solar Fraunhofer lines In physics and optics, the Fraunhofer lines are a set of spectral lines named for the German physicist Joseph von Fraunhofer (1787--1826). ...

Astronomers have found the sodium layer to be useful for creating an artificial laser guide star in the upper atmosphere. The star is used by adaptive optics to compensate for movements in the atmosphere. As a result, optical telescopes can perform much closer to their theoretical limit of resolution. An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ... Lick Observatory laser guide star, built by LLNL. Laser guide stars are a form of artificial star created for use in astronomical adaptive optics imaging. ... A deformable mirror can be used to correct wavefront errors in an astronomical telescope. ... 50 cm refracting telescope at Nice Observatory. ...

The sodium layer was first discovered in 1929. In 1939 the British-American geophysicist Sydney Chapman proposed a reaction-cycle theory to explain the night-glow phenomenon. 1929 (MCMXXIX) was a common year starting on Tuesday (link will take you to calendar). ... 1939 (MCMXXXIX) was a common year starting on Sunday (link will take you to calendar). ... Geophysics, the study of the earth by quantitative physical methods, especially by seismic reflection and refraction, gravity, magnetic, electrical, electromagnetic, and radioactivity methods. ... Sydney Chapman (January 29, 1888 – June 16, 1970) was a British astronomer and geophysicist. ...

External links

• Metallic vapor layers