A novel backscatter focus diagnostic for the TRIDENT 200 TW lasera)

Here we present the first direct focal spot images and analysis of an ultrahigh intensity short-pulse laser focus (>5×10¹⁹ W/cm²) on target. Such a focal spot characterization is typically done previous to the shot with a low-power alignment beam using equivalent plane imaging techniques. The resulting intensity of the shot is then inferred from these results. We report on the development of a backscatter focus diagnostic, which enables imaging of the on-target full-power focal spot.