Perfect X-ray focusing via fitting corrective glasses to aberrated optics

TLDR

X‑rays, owing to their short wavelength, can theoretically be focused to nanometre scales, but this same property imposes stringent requirements on optics and metrology, limiting current performance. The study aims to measure residual aberrations of a refractive X‑ray lens with ptychography and use the data to design a corrective phase plate that can be applied to any focusing optics. The authors use ptychographic imaging to precisely measure the lens aberrations and then fabricate a corrective phase plate based on those measurements. The corrective phase plate yields diffraction‑limited performance with a Strehl ratio above 0.8, producing a nearly Gaussian beam, and the approach is generalizable to other focusing optics at synchrotron and XFEL facilities.

Abstract

Abstract Due to their short wavelength, X-rays can in principle be focused down to a few nanometres and below. At the same time, it is this short wavelength that puts stringent requirements on X-ray optics and their metrology. Both are limited by today’s technology. In this work, we present accurate at wavelength measurements of residual aberrations of a refractive X-ray lens using ptychography to manufacture a corrective phase plate. Together with the fitted phase plate the optics shows diffraction-limited performance, generating a nearly Gaussian beam profile with a Strehl ratio above 0.8. This scheme can be applied to any other focusing optics, thus solving the X-ray optical problem at synchrotron radiation sources and X-ray free-electron lasers.