Diamond X-ray lens cubes with integrated aberration compensation.

Diamond is a highly suited material for radiation-resistant X-ray optics, particularly for 4th-generation synchrotron radiation sources with high brightness and X-ray free-electron laser (XFEL) facilities operating at high pulse energies. For various imaging applications, critical factors such as spatial resolution, bandwidth flexibility, and compact integration must be addressed in the design of focusing optics. However, the manufacturing process by laser ablation of diamond lenses often leads to residual aberrations and limitations in achievable spot sizes, posing challenges for high-resolution imaging applications. This work introduces an innovative concept of aberration-compensated X-ray lens cubes, composed of bi-concave, two-dimensional diamond lens plates with a 25 µm radius of curvature, fabricated by femtosecond laser ablation. A focal spot size of 52 nm × 51 nm was achieved at 14 keV, with wavefront errors strongly reduced across a wide photon energy range of 14 keV to 20 keV using multiple corrective phase plates. These results demonstrate the strong potential of our approach for nanoimaging applications, advancing high-resolution X-ray focusing capabilities for 4th-generation synchrotron radiation facilities and XFELs.