Charged-Particle Beam Wavefront Reconstruction via Image-Space Modulation
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Solution Overview
Problem
Traditional charged-particle microscopy techniques, such as electron ptychography, are limited in flexibility and versatility, particularly in wavefront reconstruction methods, which can be complicated by the introduction of aberrations from particle-optical lens systems and require constant changes in illumination conditions during measurement sessions.
Innovation Solution
The method involves using a particle-optical lens system between the sample plane and detector, with a modulator in the image space to introduce localized wavefront modulation, allowing for flexible manipulation of the wavefront without altering the illumination conditions, and employing mathematical reconstruction techniques to derive phase and amplitude information from detector outputs across multiple measurement sessions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional electron ptychography is used for wavefront reconstruction, then the method can provide wavefront information, but the flexibility and versatility are limited and the process is complicated by aberrations from particle-optical lens systems
Solution Approach 1:
The patent extracts the modulator from the traditional ptychography setup and places it in the image space of the lens system rather than in the object space. This separation allows the modulator to introduce localized wavefront modulation without being affected by illumination condition changes, thereby simplifying the reconstruction process while enhancing flexibility and versatility
Solution Approach 2:
The patent introduces a lens system as an intermediary between the sample plane and detector. This lens system creates an image space where the modulator can operate independently, mediating between the illumination conditions and the wavefront modulation process. This intermediary structure resolves the contradiction by decoupling the modulation process from illumination changes
2Measurement precision
If a modulator is placed in the object space to modulate the wavefront, then localized wavefront modulation can be achieved, but the illumination conditions must be constantly changed during measurement sessions
Solution Approach 1:
The patent moves the modulator from the object space to the image space, effectively changing the spatial dimension where modulation occurs. This dimensional shift allows the modulator to maintain localized wavefront modulation capability while operating under constant illumination conditions, thereby improving ease of operation without sacrificing measurement precision
3Loss of information
If particle-optical lens systems are used in the measurement path, then imaging and wavefront analysis can be performed, but aberrations are introduced that complicate the reconstruction process
Solution Approach 1:
The patent acknowledges that the lens system introduces aberrations, but converts this apparent harm into a benefit by using the lens system's image-forming capability to create a well-defined image space. The modulator operates in this image space, and the aberrations become part of the known system transfer function that can be accounted for in the reconstruction, thereby maintaining wavefront information completeness while managing reconstruction complexity
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 approach enhances the spatial resolution and accuracy of wavefront reconstruction, enabling more precise analysis of both the wavefront before and after interacting with the sample, while simplifying the mathematical reconstruction process and maintaining consistent illumination conditions, thus improving the accuracy of sample structure determination.
Implementation Method 1
a particle-optical lens system (LS) disposed between said sample plane and said detector
Implementation Method 2
a modulator is used to locally produce a given modulation of the wavefront
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A method of investigating a wavefront of a charged-particle beam that is directed from a source through an illuminator so as to traverse a sample plane and land upon a detector, an output of the detector being used in combination with a mathematical reconstruction technique so as to calculate at least one of phase information and amplitude information for the wavefront at a pre-defined location along its path to the detector, in which method: - Said beam is caused to traverse a particle-optical lens system disposed between said sample plane and said detector; - At a selected location in the path from said source to said detector, a modulator is used to locally produce a given modulation of the wavefront; - In a series of measurement sessions, different such modulations are employed, and the associated detector outputs are collectively used in said mathematical reconstruction.