Solid Fabry-Perot etalons for X-rays

Solid Fabry-Perot etalons for X-rays have been constructed using sputter deposition techniques, each etalon consisting of two Layered Synthetic Microstructures (LSM) Bragg diffraction structures separated by a carbon spacer. The individual LS mirrors contain fifteen tungsten layers (t_w = 8.5 Å) separated by carbon layers (t_c = 19.1 Å. The thick carbon spacers act as resonant cavities; for the structures reported on here the spacer thicknesses, t_sp, are 496.6 Å and 981 Å. The structures were characterized at grazing incidence in reflection using Cu Kα (λ = 1.5418 Å) radiation. The measured response of the etalons agrees well with calculation. Observed reflection efficiencies for Cu K_α were approximately 50 percent of that calculated. This discrepancy is believed to be the result of the interfacial roughness (～3.25 Å) between component layers and the sensitivity of the etalon response to the divergence of the incident X-ray beam.