
Free-Electron Laser - peter_d_sherman
https://en.wikipedia.org/wiki/Free-electron_laser
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peter_d_sherman
Excerpt:

"The free-electron laser is _tunable_ and has the widest frequency range of
any laser type,[3] currently ranging in wavelength from microwaves, through
terahertz radiation and infrared, to the visible spectrum, ultraviolet, and
X-ray.[4]"

