ANALYSIS OF SPHERICAL TARGET ILLUMINATION WITH PARTIALLY COHERENT-LIGHT THROUGH RANDOM-PHASE PLATE

To improve the laser irradiation uniformity on a spherical target in i nertial confinement fusion research, partially coherent light (PCL) wi th an angular spectral dispersion was introduced into a high power las er system. The calculation procedure is presented to estimate the irra diation nonuniformity which depends on the coherence of the beam patte rn on the target plane. The theoretical analysis of smoothing effect o f PCL using a random phase plate is compared with the experimental res ults. The reduction factor of irradiation nonuniformity is defined as the ratio of the Legendre-mode amplitude of the intensity distribution of PCL to that of the coherent laser. The mode structures predicted f rom reduction factors were consistent with the experimental results fo r different values of spatial and temporal coherence of PCL.