A minor correction
"A synchrotron uses magnets to accelerate electrons to almost the speed of light, and focuses them into very precise beams of synchrotron light"
Close, but not quite. The synchrotron 'light' (you can get electromagnetic waves over a wide range of wavelengths) is produced when the electrons are forced to change direction while travelling close to the speed of light. To do this you use a series of magnets, such as a multipole wiggler.
When the electrons make these handbrake turns there has to be conservation of momentum, and the excess energy from this change in velocity is emitted as electromagnetic radiation, which is the 'light' you get.
I just like to say 'multipole wiggler'.