Holographic interferometry of laser fusion targets at 2660 A

Holographic interferometry at 2660 A has been used to study plasma blowoff from 80 micron diameter laser fusion targets. Scale lengths of 11 microns, measured with 1 micron spatial resolution, are recorded at 7 x 1020 e/cc after 800 psec of hydrodynamic expansion. These results suggest much steeper density gradients at peak irradiation intensity. The observed fringe pattern is strongly dependent on interferometric imaging, as expected for strong transverse gradient refractive media. Significant interpretive errors, which might occur in a single image classical interferometer, are avoided with this holographic technique