What does coherence length in lasers indicate?

Coherence length in lasers is a critical concept that refers to the distance over which a laser beam maintains its coherence. Coherence is a measure of correlation between the phases of the light waves emitted by the laser; a coherent beam maintains a consistent phase relationship over a certain distance. This property is fundamental for applications such as interferometry and holography, where maintaining the phase relationship over a specific distance is essential for producing accurate and high-quality results.

A laser with a long coherence length can remain coherent over a longer distance, which is particularly desirable in applications where the interference patterns need to be stable and well-defined. The coherence length is influenced by the spectral width of the laser; a narrower spectral width typically leads to a longer coherence length. Understanding this concept is vital for anyone working with lasers in optical applications.