Output Optics for Aurora: Beam Separation, Pulse Stacking, and Target Focusing

Aurora is the Los Alamos short-pulse, high-power, krypton fluoride laser system. It is now conceived of as an end-to-end technology demonstration prototype for large-scale ultraviolet laser systems of interest for short wavelength, inertial confinement fusion (ICF) investigations. The system is designed to employ optical angular multiplexing and serial amplification by electron-beam-driven KrF laser amplifiers to deliver to ICF targets a stack of pulses with a duration of 5 ns containing several kilojoules at a wavelength of 248 nm. The optical system has been designed in two phases. The first phase carries only through the amplifier train and does not include a target chamber or any demultiplexing. During first-phase design, the system was conceived of as only an amplifier demonstration and not as an end-to-end system demonstration. The design concept for second-phase optics that provides demultiplexing and carries the laser light to target is presented. Discussion of the effects of first-stage design is obligatory. At the time of writing, detailed design has begun, but no hardware exists, except for the newly completed building. Some aspects of this discussion have benefited from the first fruits of detailed design, but others are still conceptual.