Tunable Ampere Phase Plate for Charged Particle Imaging Systems

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The invention is a tunable phase plate device for charged particle imaging systems, such as electron microscopes. It creates a predictable and adjustable phase shift in the imaging beam by passing an electric current parallel to the beam, generating a magnetic field that interacts with the particles. Unlike previous solutions, the phase shift amount and spatial distribution can be precisely controlled and modeled using established physical laws, allowing for improved imaging contrast and flexibility.

Use CasesContent extracted from patent full text and abstract with AI.

• Enhancing contrast in transmission electron microscopy (TEM) for biological and material science applications.
• Enabling quantitative phase imaging and holography in electron microscopes.
• Investigating weak-phase objects, such as biological specimens, where phase contrast is essential.
• Experimental research studying magnetic and electric fields at the nanoscale using electron beams.
• Optimizing and tuning imaging parameters in real time during microscopy or focused ion beam (FIB) operations.
• In situ measurement and observation of magnetic switching processes or nanomagnetic structures.
• Reducing artifacts caused by uncontrollable charging in traditional phase plates.

BenefitsContent extracted from patent full text and abstract with AI.

• Provides a controllable and predictable phase shift thanks to the use of electric current and magnetic fields governed by well-understood physical principles (Ampere's Law, Aharonov-Bohm effect).
• Enables precise tuning of phase contrast, improving image quality for weak-phase or low-contrast specimens.
• Minimizes beam disturbance and reduces unwanted charging effects compared to conventional phase plates.
• Allows for real-time adjustment and fine-tuning (e.g., via tilt adjustment, current modulation) during imaging.
• Offers enhanced mechanical robustness and design flexibility (e.g., use of thicker wires, different conductor orientations).
• Facilitates quantitative and artifact-free phase imaging, improving the reliability and reproducibility of imaging results.
• Can be incorporated into existing charged particle imaging systems, especially TEMs, with straightforward modifications.

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Patent Abstract

The invention pertains to a phase shifting device for a charged particle imaging system, where the particles may especially be electrons. The characterizing feature of the phase shifting device according to the invention is that it comprises means to pass an electric current in a direction that has a nonzero component parallel to at least one section of the imaging beam. Preferably, the electric current is passed parallel along the section of the imaging beam. The amount of phase shift then centrosymmetrically depends on the distance between the electric current axis and the imaging beam axis. The inventors have found that the magnetic field produced by the electric current exhibits the same effect on the phase of the beam as the localized charge according to the Balossier et al. prior art. Advantageously, because the relation between the current and the magnetic field is given by Ampere's Law and the effect of the magnetic field on the beam is well understood as the Aharanov-Bohm effect, the amount of phase shift and its distribution in space are fully understood and predictable. This means that the invention provides means to apply a pre-determined, specifically desired phase shift to the beam, which was not possible with previous phase plates.