Correction of the X-ray wavefront from compound refractive lenses using 3D printed refractive structures

Area of Science:

• Optics and Photonics
• Additive Manufacturing
• X-ray Science

Background:

• Fabrication errors in X-ray optical elements lead to wavefront distortions, limiting focusing performance.
• Existing methods for characterizing and correcting X-ray optical aberrations are crucial for advanced applications.

Purpose of the Study:

• To propose and demonstrate a refractive phase corrector for compensating fabrication errors in X-ray optical elements.
• To investigate the effectiveness of a 3D-printed corrector in reducing wavefront errors of compound refractive lenses (CRLs).

Main Methods:

• At-wavelength wavefront measurements using knife-edge imaging.
• Design and fabrication of a 3D-printed, rotationally invariant corrector plate using two-photon polymerization.
• Characterization of the corrector's performance on a beryllium compound refractive lens (CRL) at Diamond Light Source.

Main Results:

• A significant reduction in the root-mean-square (r.m.s.) wavefront error of a Be CRL by a factor of six was achieved.
• Knife-edge imaging and Zernike polynomial expansion were used to quantify rotationally variant wavefront errors.
• Partial compensation was observed due to anisotropic aberrations in the CRLs, indicating the need for anisotropic correctors.

Conclusions:

• 3D-printed refractive phase correctors offer a viable solution for mitigating fabrication errors in X-ray optics.
• The study highlights the limitations of rotationally invariant correctors for anisotropic aberrations.
• A rotationally anisotropic corrector is proposed for improved focusing of CRLs in diffraction-limited applications.