Diffraction-limited storage rings (DLSR), or ultra-low emittance storage rings, are
synchrotron light sources where the
emittance of the electron-beam in the storage ring is smaller or comparable to the emittance of the x-ray photon beam they produce at the end of their
insertion devices.
These facilities operate in the soft to hard x-ray range (100eV—100keV) with extremely high
brilliance (in the order of 1021—1022 photons/s/mm2/mrad2/0.1%BW)
Together with X-ray
free-electron lasers, they constitute the fourth generation of light sources,[1] characterized by a relatively high coherent flux (in the order of 1014—1015photons/s/0.1%BW for DLSR) and enable extended physical and chemical characterizations at the nano-scale.