ABSORPTION IN HIGH-Z TARGETS ILLUMINATED WITH 527-NM LASER-LIGHT AT HIGH-INTENSITY USING INDUCED SPATIAL INCOHERENCE

We have measured 527-nm absorption for induced spatial incoherence (ISI) and non-ISI illumination ofhigh- Z targets over the 0.5-3.5 X 1014-W/cm2 laser intensity range using energy balance with a custom designed 30­cm diam light integrating sphere. Induced spatial incoherence of the laser beam was produced by inserting echelons in the beam path and operating the laser at wide bandwidth (0.2%). To produce ISI and non-ISI data for comparison, we irradiated a large number of 180-Mm diam gold disks with 0.5-1.5-ns pulses with echelons in the beam path with and without wide laser bandwidths. Our data show an increase in absorption of 5-11% for the ISI illuminated targets and also suggest a weaker dependence of absorption on laser intensity for ISI illumination than for non-ISI. © 1990 Optical Society of America.