An evaluation of target irradiation uniformity based on spatial-spectrum analysis

The irradiation uniformity of target spots in high-power laser driver is evaluated based on spatial-spectrum analysis. Spatial spectrum can display the detailed spatial intensity structure of the spots and show the spatial frequency modes smoothed by the beam smoothing techniques. This evaluating model is applied to two kinds of typical target spots obtained with a lens array and a random phase plate, respectively, and its validity is found to be independent of the spot profile and the degree of intensity modulation. The uniformity evaluations based on this model are in good agreement with the fractional power above intensity.