Charged Particle Vortex Wave Generation via Angular Phase Gradient
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Solution Overview
Problem
Existing methods for producing electron vortex beams, such as holographic reconstruction and phase gratings, suffer from inefficiencies like generating secondary waves and limited current availability, making it difficult to achieve high signal-to-noise ratios and precise control over orbital angular momentum.
Innovation Solution
A device comprising angularly spaced electrical conductors with a potential difference inducing an angular gradient of the phase in a charged particle beam, allowing for efficient production of a vortex wave with tunable and rapidly controllable orbital angular momentum, which can be integrated into existing electron microscopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If holographic reconstruction techniques are used to produce electron vortex waves, then vortex beams can be generated, but secondary waves are simultaneously produced and current is distributed over multiple beams reducing signal-to-noise ratio
Solution Approach 1:
The patent extracts only the desired vortex wave component by using a phase grating that selectively diffracts electrons into a single vortex beam order while suppressing other beam components. The phase grating structure with spiral geometry is designed to convert a plane wave incident beam into a single vortex wave with topological charge m, eliminating the generation of multiple beam orders that plague holographic methods.
Solution Approach 2:
The patent introduces a phase grating as an intermediary element between the electron source and detector. This phase grating acts as a mediator that transforms the incident electron beam into a vortex beam through controlled phase modulation, while the electrostatic potential applied to the grating structure enables precise control over the vortex beam properties without generating unwanted secondary waves.
2Reliability
If phase gratings are used to produce electron vortex beams, then vortex waves can be generated, but electron current is limited and difficult to control
Solution Approach 1:
The patent implements dynamic control of the vortex beam by applying variable electrostatic potentials to the phase grating structure. The orbital angular momentum of the generated vortex beam can be continuously tuned by adjusting the applied voltage, and the beam can be rapidly switched between different topological charges. This dynamic control mechanism enables real-time adjustment of beam properties without mechanical movement or complex reconfiguration.
Solution Approach 2:
The patent changes the electrostatic potential parameter of the phase grating to control the orbital angular momentum of the generated vortex beam. By varying the applied voltage across a wide range, the topological charge m of the vortex beam can be precisely controlled, enabling flexible adjustment of the beam's angular momentum while maintaining stable current levels.
3Measurement precision
If EMCD technique is used for magnetic information in EELS, then magnetic information can be obtained, but spatial resolution is limited to bigger than a few unit cells
Solution Approach 1:
The patent replaces the mechanical diffraction-based EMCD technique with a vortex beam-based approach. Instead of relying on Bragg scattering and crystal orientation, the method uses electron beams with inherent orbital angular momentum to probe magnetic properties. This substitution eliminates the spatial resolution limitations of EMCD while maintaining the ability to obtain magnetic information through angular momentum conservation in inelastic scattering processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables the isolation of a single vortex wave with high particle current, improved signal-to-noise ratio, and flexible control over orbital angular momentum, enhancing the capabilities of electron microscopes without significant current loss.
Implementation Method 1
a first conductive element and a second conductive element spaced apart from each other in a direction along the axis and adapted for transmitting a charged particle wave propagating along the axis. The connecting means is adapted for supplying an electrical potential difference over the first conductive element and the second conductive element, in which the connecting means is adapted for supplying an electrical potential to the plurality of angularly spaced electrical conductors for inducing an angular gradient of the phase of the charged particle wave when transmitted along the axis
Data Source
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AI summary
A device (100) for imparting an orbital angular momentum to a charged particle wave propagating along an axis (105) in a charged particle beam generating apparatus, the device comprising a first conductive element (110) comprising a plurality of angularly spaced electrical conductors (112) arranged around the axis (105), a second conductive element (120), in which said first conductive element (110) and said second conductive element (120) are spaced apart along the direction of said axis (105), and in which said first conductive element (110) and said second conductive element (120) are adapted for transmitting a charged particle wave propagating along said axis (105), and a connecting means (130) for supplying an electrical potential difference over said first conductive element (110) and said second conductive element (120). The connecting means (130) is adapted for supplying an electrical potential to said plurality of angularly spaced electrical conductors (112) for inducing an angular gradient of the phase of the charged particle wave when transmitted along said axis (105), in which the projection along the axis (105) of the electrical potential varies as function of an angular position with respect to the axis (105).