= Lasers vs other light sources
The key advantages of lasers over other <light sources> are:
* <lasers emit a narrow spectrum>
* it can be efficient collimated, while still emitting a lot of output power: <Why can't you collimate incoherent light as well as a laser?>{full}
* can be phase and polarization coherent, though it is not always the case? TODO.
One cool thing about <lasers> is that they rely on one specific atomic energy level transition to produce light. This is why they are able to to be so monchromatic. Compare this to:
* incandescent bulbs: wide <black-body radiation> spectrum
* <LED>: has a wider spectrum fundamentally related to an energy distribution, related: <Why aren't LEDs monochromatic>
* TODO think a bit about <fluorescent lamps>. These also rely on atomic energy transitions, but many of them are present at once, which makes the spectrum very noisy. But would individual lines be very narrow?
As such, lasers manage to largely overcome "temperature distribution-like" effects that create wider wave spectrum
\Video[https://www.youtube.com/watch?v=vUwP7SY0Ajs]
{title=Crazy difference between 5<Watt>[W] <laser> and 5W <LED> by Brainiac75}
{description=Baseic but good. Uses a <laser> <photometer>.}