Design of kinoform phase plate arrays for spatial beam smoothing

It has been widely accepted that spatial beam smoothing is essential in cou pling laser energy to inertial confinement fusion targets. In this paper, k inoform phase plate arrays have been proposed to produce spatially homogeni zed far fields for a broad range of phase and irradiance non-uniformities i n the incident beam. A global-local united search algorithm has been presen ted to design a phase plate element to concentrate more than 95% energy of laser beams on a flat-top super-Gaussian (SG) envelope. A spatial-fining te chnique has been proposed to control the intermediate-spatial-frequency ove rlapping intensity modulation generated by various phase plate elements. Fo r a flat incident aperture size of 40 cm, a laser wavelength of 351 nm, and a lens focal length of 1000 mm, 10 x 10 phase plate arrays have been desig ned to produce sixteenth-order SG profiles with the intensity modulation in terval less than 5 mu m. More than 96% of the incident energy is homogeneou sly constrained in the desired region.