Fabrication of large aperture kinoform phase plates in fused silica for smoothing focal plane intensity profiles

In laser driven inertial confinement fusion systems, it is necessary to produce smooth focal plane intensity profiles [1]. The desired intensity distribution consists of a superGaussian envelope with a superimposed speckle on it. The speckle pattern is smoothed either by the plasma or by other temporal smoothing techniques. Binary random phase plates (RPPs) are inadequate for spatial smoothing as they lead to Airy function envelopes in the far-field and are only 84 % efficient. Furthermore RPPs also introduce large intensity modulations in the propagated intensity past the RPP which can potentially damage the optics downstream from the RPPs.