Design and quantitative analysis of diffractive optical element to realize true beam smoothing on an inclined plane

摘要

Diffractive optical element (DOE) is a proposing technique to realize beam smoothing in inertial confinement fusion (ICF) system. In indirect-driving ICF system, beam smoothing is required on a certain inclined plane non-perpendicular to the optical axis. In this paper, the DOE is designed to be consistent with beam smoothing with long focal depth, which ensures that the beam smoothing can be obtained on the inclined plane. And in the optimization, the sampling interval is chosen as half of the traditional sampling interval, in order to realize true beam smoothing distribution. The simulated results show that the performance of the beam smoothing can be held with any sampling interval on the inclined plane. Finally, the performance of the DOE is quantitatively analyzed. Two parameters, light efficiency and top non-uniformity, are re-defined. These two parameters can truly and exactly evaluate the performance of the DOE, because their definitions can go back to the origin. The simulated results show the validity of the design with long focal depth and half of the traditional sampling interval.