KMSF laser subsystems

A laser amplifier, rod or disk, has a well defined aperture that limits the diameter of the beam. If one attempts to fill this entire aperture with useful energy, the interaction of the beam with the hard limiting aperture produces Fresnel diffraction rings at the edge which will propagate throughout the beam. These diffraction rings will be amplified by later amplifiers, resulting in intensity modulation detrimental to the beam propagation and even initiating self-focusing with consequent damage to optical components.