Formation of a beam profile at the input to a high-energy laser amplifier

A device consisting of a pin-hole line and an apodizing aperture, which provides the fill factor of the laser amplifier aperture equal to 0.8, is proposed and studied experimentally. The use of this device allowed the generation of 300-J, 1-ns pulses due to the efficient energy extraction from a six-stage neodymium phosphate glass amplifier with the final stage aperture equal to 10 cm.