High-efficiency zone-plate optics for multi-keV X-ray focusing

Area of Science:

• Optics and Photonics
• X-ray Science and Technology
• Materials Science

Background:

• Achieving high-efficiency focusing of hard X-rays is crucial for advanced imaging and spectroscopy.
• Traditional Fresnel zone plates (FZPs) have limitations in efficiency due to their binary or multilevel structures.
• Approximating ideal parabolic lens profiles is key to enhancing X-ray focusing performance.

Purpose of the Study:

• To demonstrate high-efficiency nanofocusing of hard X-rays.
• To investigate the use of stacked multilevel Fresnel zone plates (FZPs) for improved focusing.
• To approximate ideal parabolic lens profiles using two-, three-, four-, and six-level zone plates.

Main Methods:

• Fabrication of stacked multilevel Fresnel zone plates with a minimum zone width of 200 nm.
• Approximation of parabolic lens profiles using 2, 3, 4, and 6 levels.
• Stacking binary and three-level FZPs to create four- and six-level optical transmission functions.
• Experimental focusing of 6.5 keV photons using a compact piezoelectric actuator-based alignment apparatus.
• Comparison of experimental measurements with numerical simulations to analyze zone plate misalignment.

Main Results:

• Demonstrated high-efficiency nanofocusing of hard X-rays.
• Achieved experimental focusing efficiencies up to 53.7% for 6.5 keV photons.
• Successfully approximated parabolic lens profiles using stacked multilevel FZPs.
• Numerical simulations were used to study the impact of misalignment between stacked zone plates.

Conclusions:

• Stacked multilevel Fresnel zone plates offer a viable approach for high-efficiency hard X-ray nanofocusing.
• The developed method allows for efficient approximation of ideal parabolic lens profiles.
• The achieved efficiencies and simulation studies provide a strong foundation for future X-ray optics development.