Fourier-transform ring laser

A Fourier-transform ring laser has been designed and toleranced to produce a good-quality beam from a solid-state laser. Extremely high volumetric utilization of the gain distribution is accomplished by injecting a super-Gaussian-shaped beam profile of uniform phase and nearly uniform intensity into the ring resonator. This beam fills most of the rod and is reproduced at the rod center in both intensity and phase by an exact Fourier-transform relay lens scheme. The laser is shown to be most stable when the diameter of the super-Gaussian beam is equal to diameter of the eigenmode for the optical system. It is shown to be most reliable when the relay system has a magnification such that the beam expands from its initial eigenmode size to fill the rod on its final pass.