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Proceedings Paper

Wavefront control system for the National Ignition Facility (NIF)
Author(s): Richard A. Zacharias; Erlan S. Bliss; Mark Feldman; Andrew Grey; Jeffrey A. Koch; Richard A. Sacks; John S. Toeppen; Lewis Van Atta; Scott Winters; Bruce W. Woods
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Paper Abstract

The use of lasers as the driver for inertial confinement fusion experiments and weapons physics applications is based on their ability to produce high-energy short pulses in a beam with low divergence. Indeed, the focusability of high quality laser beams far exceeds alternate technologies and is a major factor in the rationale for building lasers for such applications The National Ignition Facility (NIF) is a large 192-beam laser facility now under construction at the Lawrence Livermore National Laboratory for fusion and weapons physics experiments. Its uncorrected focal spot minimum size is limited by wavefront aberrations in the laser system. NIF is designed with a wavefront control system to correct these aberrations to yield a focal spot that is small enough for NIF' s intended applications. Sources of aberrations to be corrected include prompt pump-induced distortions in the laser amplifiers, thermal distortions in the amplifiers from previous shots, beam off-axis effects, and gravity, mounting, and coating-induced optic distortions. Aberrations from gas density variations and manufacturing figure errors in the optics are also partially corrected by the wavefront control system. The NIF wavefront control system consists of five subsystems for each of the 192 beams: 1) a deformable mirror, 2) a wavefront sensor, 3) a computer controller, 4) a wavefront reference system, and 5) a rapid reconfiguration system to allow the wavefront control system to operate to within one second of the laser shot. The system includes the capability for in situ calibrations and operates in closed loop prior to the shot. Shot wavefront data is recorded. This paper describes the function, realization, and performance of each wavefront control subsystem. Subsystem performance will be characterized by computer models and by test results. The focal spot improvement in the NIF laser system effected by the wavefront control system will be characterized through computer models. The sensitivity of the target focal spot to various aberration sources will be presented. Analyses to optimize the wavefront control system will also be presented.

Paper Details

Date Published: 19 July 1999
PDF: 2 pages
Proc. SPIE 3749, 18th Congress of the International Commission for Optics, (19 July 1999); doi: 10.1117/12.354735
Show Author Affiliations
Richard A. Zacharias, Lawrence Livermore National Lab. (United States)
Erlan S. Bliss, Lawrence Livermore National Lab. (United States)
Mark Feldman, Lawrence Livermore National Lab. (United States)
Andrew Grey, Lawrence Livermore National Lab. (United States)
Jeffrey A. Koch, Lawrence Livermore National Lab. (United States)
Richard A. Sacks, Lawrence Livermore National Lab. (United States)
John S. Toeppen, Lawrence Livermore National Lab. (United States)
Lewis Van Atta, Lawrence Livermore National Lab. (United States)
Scott Winters, Lawrence Livermore National Lab. (United States)
Bruce W. Woods, Lawrence Livermore National Lab. (United States)


Published in SPIE Proceedings Vol. 3749:
18th Congress of the International Commission for Optics
Alexander J. Glass; Joseph W. Goodman; Milton Chang; Arthur H. Guenther; Toshimitsu Asakura, Editor(s)

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