The LMJ (Laser MegaJoule) is dedicated to inertial confinement fusion. To perform this type of experiment, 160 square beams are frequency converted and focused onto a target filled with a deuterium tritium mixture. We propose to review how these beams are shaped along their propagation through the LMJ. Going upstream from the target to the laser source, specific optics has been designed to meet the beam shaping requirement. A focusing grating and a pseudorandom phase plate concentrate the energy onto the target. A deformable mirror controls and compensates the spatial phase defect occurring during the propagation through the main slab amplifiers. A liquid crystal cell shapes the beam in order to compensate the gain profile of the main amplifiers. It also protects the growth of damages that take place in the final optics of the chain. At last, a phase mirror generates a square flat top mode from a gaussian beam within a regenerative amplifier. All these optical components have one common principle: they control the phase of the spatial laser field.

Date Published: 6 September 2011
PDF: 6 pages
Proc. SPIE 8130, Laser Beam Shaping XII, 813002 (6 September 2011);

Published in SPIE Proceedings Vol. 8130:
Laser Beam Shaping XII
Andrew Forbes; Todd E. Lizotte, Editor(s)