Why do lasers produce such narrow beams of light?
Quick Answer
Lasers produce narrow beams because their light is generated by stimulated emission, which creates photons that are in step with one another. Mirrors inside the laser cavity reinforce a very specific direction and wavelength.
The Full Story
A laser works by amplifying light through stimulated emission, a process predicted by Einstein in 1917. In the laser cavity, excited atoms or molecules release photons that match an incoming photon’s phase, direction, and wavelength. The mirrors at each end of the cavity select and strengthen certain modes, so the output is highly directional and often nearly monochromatic. This makes lasers useful in surgery, communication, scanning, and precision measurement.
Key Facts
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"Why does laser light stay so tight and straight?"
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