coherence length
Quick Summary
In physics, coherence length refers to the distance over which a wave maintains a fixed phase relationship with itself. This concept is crucial for understanding phenomena like interference, which occurs when waves combine.1
Radiation from sources like the Sun or a lightbulb typically comes in short wave trains with a coherence length of about one centimeter. In contrast, a laser produces a beam where all components maintain a fixed phase relationship, resulting in a much longer coherence length.21
The coherence length is related to the spectral width of the radiation. A narrower frequency bandwidth leads to a longer coherence length, allowing for more stable interference patterns.3
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