Post-acquisition upsampling method for scanning x-ray microscopy

Area of Science:

• Materials Science
• Microscopy Techniques
• Computational Imaging

Background:

• Scanning x-ray microscopy (SXM) is limited by the Nyquist frequency, restricting spatial resolution.
• Achieving higher resolution often requires smaller probe beams or denser scanning, which can be impractical.
• Existing methods struggle to resolve fine details when probe size is comparable to pixel size.

Purpose of the Study:

• To develop a post-acquisition upsampling method for SXM to improve spatial resolution.
• To enable imaging beyond the Nyquist frequency limitations of raster scanning.
• To enhance the analysis of complex magnetic materials using SXM.

Main Methods:

• A novel post-acquisition upsampling technique based on solving a stochastic inverse problem.
• Estimation of unconvoluted spatial variation at a higher resolution than data acquisition.
• Application to raster micrographs of x-ray absorption and x-ray magnetic circular dichroism (XMCD) in Nd-Fe-B magnets.

Main Results:

• Demonstrated improvement in spatial resolution beyond the Nyquist frequency.
• Successfully applied the method to Nd-Fe-B magnets, revealing magnetic field-induced domain pattern changes.
• Numerical verification of resolution enhancement using discrete Fourier transform and spectral analysis.

Conclusions:

• The developed upsampling method effectively enhances spatial resolution in SXM.
• The technique is particularly useful when probe beam size is not negligible compared to pixel size.
• This computational approach significantly improves the viability of SXM for advanced materials characterization.