Broadband, high-resolution, soft x-ray imaging

Fresnel zone plates (FZP’s) are gaining popularity in laser-plasma experiments where their implementation to image hard x-rays (≥4 keV) results in spatial resolutions near 1 µm, far exceeding that obtained with pinholes. This is particularly useful to study hydrodynamic instabilities where density modulations and spatial scales are very small. Applying this diagnostic to laser-imprint measurements, or probing driven shell density profiles in inertial confinement fusion studies, is problematic due to the necessity of soft x-rays in the 1-1.5 keV range where a monoenergetic x-ray line is difficult to produce (FZP’s are highly chromatic). Recently, an x-ray achromat consisting of an FZP and a refractive lens (RL) has been successfully demonstrated at an x-ray energy of 6.5 keV. Applying this concept in the soft x-ray regime would not only solve the problem of needing a monochromatic line, but would allow for the use of bright M-band or L-band backlighter sources while sustaining high-imaging resolution. The difficulty in this approach is the large absorption of soft x-rays in the RL. Research progress in attempt to design a functional broadband soft x-ray imager will be presented.

This material is based upon work supported by the Department of Energy [National Nuclear Security Administration] University of Rochester “National Inertial Confinement Fusion Program” under Award Number DE-NA0004144.