Such a beam can result from a single-frequency laser, when its output is sent through some optically inhomogeneous material. On the other hand, the beam is monochromatic, so that the spacing of the deformed wavefronts remains constant.
The wavefronts are deformed, and this results in a high beam divergence and poor beam quality. Figure 3:Ī laser beam with high spatial coherence, but poor temporal coherence.įigure 4 shows a laser beam with reduced spatial coherence, but high temporal coherence. from the output of a supercontinuum source. Note that both the local amplitude and the spacing of the wavefronts vary to some extent. The wavefronts are formed as above, and the beam quality is still very high, but the amplitude and phase of the beam varies along the propagation direction. from the left side) with perfect spatial and temporal coherence.įigure 3 shows a beam with high spatial coherence, but poor temporal coherence. Figure 2:Įlectric field distribution around the focus of a Gaussian laser beam (coming e.g.
There are various ways of quantifying the degree of coherence, as described below. Partial coherence means that there is some (although not perfect) correlation between phase values.
How to cite the article suggest additional literatureĬoherence is one of the most important concepts in optics and is strongly related to the ability of light to exhibit interference effects.Ī light field is called coherent when there is a fixed phase relationship between the electric field values at different locations or at different times. More specific terms: phase coherence, temporal coherence, spatial coherence
Related Application Note fromĪsk RP Photonics for advice concerning the measurement and the effects of coherence in optical systems.ĭefinition: a fixed phase relationship between the electric field values at different locations or at different times Using our ad package, you can display your logo and further below your product description.