Spatial Coherence
Definition and meaning of Spatial Coherence in chemistry.
Spatial coherence is a measure of the phase correlation between different points across a wave front at a specific moment in time.
In more detail
In instrumental spectroscopy and advanced optics, a highly spatially coherent light source produces electromagnetic waves that remain uniform and predictable across their entire cross-sectional area. This strong phase relationship means that the light beam can be precisely focused down to a microscopically small spot, or it can remain in a tight, parallel beam over exceptionally long distances without spreading out significantly. Modern lasers are the most common highly spatially coherent light sources used in precise chemical laboratory instruments.
Key facts
| Field | Physical Chemistry |
|---|---|
| Application | Lasers and optical spectroscopy |
| Formula Example | He-Ne |
The bright beam of a laboratory helium-neon laser maintains a very narrow, intense profile over a long distance precisely because of its incredibly high spatial coherence.
Frequently asked questions
Why is spatial coherence important in spectroscopy?
It allows the light beam to be efficiently focused onto very small samples or coupled into optical fibers.
How does it differ from temporal coherence?
Temporal coherence relates to the phase correlation of a wave over time along the direction of propagation, which is related to the monochromaticity of the source.