Optical system design of the National Ignition Facility

The National Ignition Facility (NIF) is a laser fusion facility being constructed at Lawrence Livermore National Laboratory (LLNL). The neodymium-doped phosphate glass pulsed laser system will produce over 3.5MJ of laser energy at a fundamental lasing wavelength of 1.053 mu m (1 omega). The final optics assembly contains a pair of crystals (KDP/KD*P) and a focusing lens to convert the light by sum-frequency-mixing to 3 omega (lambda=0.35 mu m) and focus 1.8MJ onto the target. The NIF optical system is large and complex. To give some perspective the NIF building is roughy 200 meters long x 85 meters wide. There are approximately 7500 optical components in the large aperture laser system - lenses, mirrors, polarizers, laser slabs, crystals, and windows each with a clear aperture greater than 40cm square. The front-end of the laser system contains more than 8000 smaller (5-15cm) precision laser components. In this paper we will describe the optical system configuration, layout, and general design considerations. We will explain the path of the pulse through the various subsystems. Some of the top-level optical system and sub-system design requirements will be presented.