Measurement of 0.35 mu m laser imprint in a thin Si foil using an x-ray laser backlighter

Imprinted modulations in optical depth of a thin Si foil due to 0.35 mu m laser irradiation at about 3 x 10(12) W/cm(2) have been measured at shock breakout, These measurements were made by high resolution face-on radiography using a gain saturated yttrium x-ray laser backlighter operating at a wavelength of 15.5 nm with a multilayer optics imaging system. The imprinted modulation due to a static speckle pattern and a 0.29 and a 0.33 THz spectral dispersion smoothed speckle pattern were studied. Comparison of the imprinted modulation is made with simulations.