High-throughput, high-resolution Kirkpatrick–Baez microscope for advanced streaked imaging of ICF experiments on OMEGA

Abstract

A Kirkpatrick-Baez (KB) x-ray microscope with a streak camera at the image plane is being developed for OMEGA to increase the sensitivity and spatial resolution in planar direct-drive hydrodynamic stability experiments. A four-mirror, iridium-coated, KB optic has been designed to couple to the high-current PJX streak tube. This design, using a bilayer Ir/Cr coating and a relatively high grazing angle of 2.1°, provides up to three-orders-of-magnitude-higher throughput than a pinhole array coupled to an x-ray framing camera. The angle of reflection has been calculated to maximize the solid angle and the coating reflectivity. The spectral window, peaked at 1.56 keV with a FWHM of about 400 eV, eliminates the contrast impairment caused by the high-energy x-ray emission of the backlighter. Calculations show that the device is capable of registering 2-μm spatial features over a field of view of 120 μm. A series of sputtering and e-beam evaporation deposition tests have been performed on superpolished (<0.1 nm rms) test plates to determine the density and smoothness of the film. Detailed ray tracing has been used to fully characterize and optimize the optical parameters of the system, including diffraction response. Its resolving capabilities and throughput have been confirmed by several test experiments.