Comparison of optical beam smoothing techniques for inertial confinement fusion and improvement of smoothing by the use of zero-correlation masks
- Plasma Physics Division, U. S. Naval Research Laboratory, Washington, DC 20375 (United States)
- Lawrence Livermore National Laboratory, L-482, P.O. Box 808, Livermore, California 94550 (United States)
We present analytic theory and numerical simulations comparing the optical beam smoothing capabilities of the smoothing by spectral dispersion (SSD) technique using random temporal phase modulation, with that of the induced spatial incoherence technique. The analytic theory provides a simple formula for the SSD mode spectrum in the usual case where the phase mask at the focusing lens is random, and its asymptotic limit quantitatively relates the long wavelength mode smoothing to the width of the angular dispersion. With parameters and phase aberration relevant to the National Ignition Facility beams, the SSD simulations show that the large long wavelength components, which are also found in earlier simulations, can be significantly reduced by replacing the independent random phase masks in each pair of adjacent beams by a conjugate pair of zero-correlation masks. These simulations suggest that one can combine zero-correlation masks with random temporal phase modulation and multiple color cycles to achieve SSD smoothing approaching the optical bandwidth limit at all spatial frequencies, without using large angular dispersions. (c) 2000 American Institute of Physics.
- OSTI ID:
- 20215174
- Journal Information:
- Journal of Applied Physics, Vol. 87, Issue 3; Other Information: PBD: 1 Feb 2000; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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