Beams with a minimum possible Beam Divergence for a given waist radius.

A Laser beam is called diffraction-limited IF its potential to be focused to small spots is as high as possible for the given wavelength, i.e., if its Beam Quality is ideal. More precisely, this means that a Beam Waist with a given beam radius, generated from the beam by focusing with a curved mirror, is associated with the minimum possible beam divergence.