Characterization of X-ray contact microscopic imaging in keV spectral region using laser produced plasmas

An experimental study is performed of soft X-ray emission from laser produced plasmas for single shot X-ray contact microscopic imaging of physical and biological microstructures. Planar copper targets are irradiated by 10 J, 28 nS Nd:glass laser pulses in the intensity range of 1011 W/cm2 to 3 × 1012 W/cm2. Measurements of keV X-ray emission viz. X-ray intensity scaling with laser intensity, X-ray source size, X-ray conversion efficiency and exposure dose on the sample are presented. Fine copper grids of 70 mm mesh size and 10 mm thickness are used as test samples for imaging on ERP-40 photoresist. A spatial resolution of ~195 nm is observed, consistent with theoretical estimate considering the contribution of geometrical and diffraction blurring, and statistical noise of photons incident on the sample. This study should be useful in proper selection of source parameters for optimization of spatial resolution in single shot keV contact imaging.