Recording low and high spatial frequencies in exit wave reconstructions

Area of Science:

• Materials Science
• Microscopy
• Physics

Background:

• Aberration corrected Transmission Electron Microscopy (TEM) achieves sub-0.1 nm resolution.
• Optimized high-resolution imaging in TEM sacrifices low spatial frequency information.
• Acquiring low-frequency data requires large defocus, compromising high-frequency transfer.

Purpose of the Study:

• To present two a posteriori solutions for increasing information bandwidth in exit wave reconstruction.
• To recover lost low spatial frequency information in aberration corrected TEM images.
• To enhance the overall spatial resolution and detail in TEM imaging.

Main Methods:

• Reconstructing the electron exit wavefunction from two focal series datasets with different uniform focal steps.
• Utilizing a focal series recorded with a non-uniform focal step for wider spatial frequency recovery.
• Employing simulated data to validate the non-uniform focal step approach.

Main Results:

• Demonstrated extension of the transfer interval from 0.2 nm⁻¹ (∼5 nm) to >10 nm⁻¹ (0.1 nm) using dual focal series.
• Showcased recovery of a wider spatial frequency range with a non-uniform focal step series.
• Increased the spatial frequency interval for a five-image dataset using non-uniform focal steps.

Conclusions:

• The presented methods effectively increase the information bandwidth in exit wave reconstruction.
• These techniques overcome the limitations of conventional aberration corrected TEM imaging.
• Enhanced spatial frequency recovery leads to improved detail and resolution in TEM images.