X-ray focusing with efficient high-NA multilayer Laue lenses

Abstract

Multilayer Laue lenses are volume diffraction elements for the efficient focusing of X-rays. With a new manufacturing technique that we introduced, it is possible to fabricate lenses of sufficiently high numerical aperture (NA) to achieve focal spot sizes below 10 nm. The alternating layers of the materials that form the lens must span a broad range of thicknesses on the nanometer scale to achieve the necessary range of X-ray deflection angles required to achieve a high NA. This poses a challenge to both the accuracy of the deposition process and the control of the materials properties, which often vary with layer thickness. We introduced a new pair of materials—tungsten carbide and silicon carbide—to prepare layered structures with smooth and sharp interfaces and with no material phase transitions that hampered the manufacture of previous lenses. Using a pair of multilayer Laue lenses (MLLs) fabricated from this system, we achieved a two-dimensional focus of 8.4 × 6.8 nm2 at a photon energy of 16.3 keV with high diffraction efficiency and demonstrated scanning-based imaging of samples with a resolution well below 10 nm. The high NA also allowed projection holographic imaging with strong phase contrast over a large range of magnifications. An error analysis indicates the possibility of achieving 1 nm focusing.

Dose efficient Compton X-ray microscopy

“…Our proposed scanning microscopy technique could take advantage of new high-energy synchrotron light sources based on the multibend-achromat [15] that will provide large coherent fluxes at photon energies above 50 keV. This can be combined with new technologies for hard X-ray nanofocusing [13,14,36,37], to achieve dose-optimized and fast X-ray imaging. An advantage of the high photon energy used for SCXM is that the attenuation length of biological material is large, as is the depth of focus.…”

“…(2)]. The required techniques to fabricate such lenses have recently been demonstrated [36,37]. Being diffractive lenses, the focal length of a MLL varies inversely with wavelength, as shown schematically in Fig.…”

Three dimensions, two microscopes, one code: Automatic differentiation for x-ray nanotomography beyond the depth of focus limit

“…Depending on the photon energy used, X rays are able to penetrate into samples with a thickness ranging from micrometers to centimeters. At the same time, x-ray microscopes are beginning to be able to deliver images with sub-10 nanometer spatial resolution (1)(2)(3)(4). However, combining these characteristics is complicated by the fact that any imaging method with spatial resolution δ r has a depth of focus DOF limit (5,6) of…”

7 nm Spatial Resolution in Soft X-ray Microscopy

“…Development in microscopic methods has always aimed for achieving spatial resolutions as high as possible. Although highly confined X-ray beams with spot sizes well below 10 nm have been characterized in recent years using mirrors [1], Fresnel zone plate (FZP) lenses [2,3] or multilayer Laue lenses [4,5], X-ray imaging with single-digit nanometer resolution remains an extreme challenge.We report on unprecedented spatial resolution down to 7 nm achieved at two soft X-ray microscopes using photon energies between 700 eV and 850 eV. The experiments were performed at the scanning transmission X-ray microscopes (STXM) at the PolLux beamline at the Swiss Light Source [6] and the Hermes beamline at Synchrotron Soleil [7].…”

“…Development in microscopic methods has always aimed for achieving spatial resolutions as high as possible. Although highly confined X-ray beams with spot sizes well below 10 nm have been characterized in recent years using mirrors [1], Fresnel zone plate (FZP) lenses [2,3] or multilayer Laue lenses [4,5], X-ray imaging with single-digit nanometer resolution remains an extreme challenge.…”