Compact diamond x-ray lens cubes for nanofocusing

Nanofocusing with refractive x-ray optics requires the combination of many single lenses into a larger lens stack to achieve high numerical apertures. So far, these optics have suffered from aberration due to accuracy limitations in x-ray lens manufacturing. Refractive phase plates have been used to compensate these errors, but require separate alignment and wavefront metrology. Here, we present the concept of x-ray lens cubes, a new assembly strategy developed for laser-ablated diamond x-ray lenses. It allows to integrate a diamond phase corrector directly into the quasi-monolithic assembly, creating lens cubes that contain several lenses with a matching and pre-aligned phase corrector. We show the experimental validation of individual lens cubes, as well as the combination of two cubes to form a larger lens stack. The concept and advantages of integrating multiple phase plates into a lens assembly are validated by numerical simulations. Aberration-compensated lens cubes can offer near diffraction-limited imaging performance over a broad x-ray energy range in combination with easy alignment, providing broad practical applicability for nano-imaging experiments in the hard x-ray regime.