Coherence and lasers
Advanced
Stimulated emission produces coherent beams.
Lasers emit light that is nearly monochromatic, coherent and highly directional through stimulated emission in a resonant cavity.
Laser pointers, surgery and barcode readers.
Not necessarily powerful.
In more detail
Coherence describes how well light waves maintain a constant phase relationship. Lasers are highly coherent in space and time, which makes them useful for interference and precision measurements.
Real-world uses
- Lasers are used in precision measurement and communication.
- Holography uses laser coherence to record interference patterns.
- Lasers produce an intense, coherent beam for cutting, surgery, barcode reading and optical communication.
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Frequently asked questions
What is spatial coherence?
The correlation of phase across different points on a wavefront.
What is temporal coherence?
The correlation of phase at a single point over time, related to the bandwidth of the light.
What makes a laser coherent?
Stimulated emission produces photons with the same frequency, direction and phase, which makes the beam tightly focused.
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