Abstract

Spatial and temporal beam smoothing has now become an integral part of laser-driven inertial confinement fusion (ICF) worldwide. Spatial smoothing is often achieved by creatunga fine scale speckle pattern using random phase plates (RPP) or lenslet arrays. Temporal smoothing is accomplished by causing the speckle pattern to move in time using smoothing by spectral dispersion (SSD) or induced spatial incoherence (ISI). All the EPPs used so far have consisted of random layouts of square, rectangular, or hexagonal phase plate elements that impose either 0 or π phase shift on the beam. The central maximum of the far-field envelope for square and hexagonal shapes is qualitatively similar to an Airy pattern, and it contains 81-84% of the incident energy. Even though such regular element binary phase plates are easy to fabricate and are widely used, they offer little flexibility in our ability to tailor the far-field profile and to increase the energy content in the central maximum beyond the 84% predicted for a circular aperture.

© 1993 Optical Society of America