Diffraction Pattern Detection in Transmission Charged Particle Microscope
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Solution Overview
Problem
Charged-particle microscopy, particularly in Transmission Electron Microscopes, faces a challenge in recording diffraction patterns at low doses, which minimizes radiation damage but degrades signal quality, making it difficult to capture high-resolution images of organic and inorganic samples without compromising detector integrity.
Innovation Solution
Implementing a detector in particle counting mode, recording diffraction patterns iteratively with relative motion between the diffraction pattern and detector, smearing out intense peaks across multiple pixels to reduce dose per pixel and mitigate pile-ups, allowing for higher count rates and accurate determination of peak positions and intensities through computational deconvolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the dose is reduced to minimize radiation damage, then specimen damage is reduced, but signal quality deteriorates
Solution Approach 1:
The patent applies periodic action by moving the detector in a scanning pattern across the diffraction pattern over time, recording multiple frames. This temporal scanning allows accumulation of signal from many low-dose exposures, achieving high signal quality without increasing the dose per pixel beyond safe limits for the specimen.
Solution Approach 2:
The patent transitions from a static detector position to dynamic motion in spatial dimensions, causing each detector element to sample multiple positions in the diffraction pattern. This dimensional transformation converts a low-dose, low-signal problem into a time-integrated, high-signal measurement while maintaining low instantaneous dose.
2Measurement precision
If the dose per pixel is increased to improve signal quality, then measurement precision improves, but detector damage increases
Solution Approach 1:
The patent segments the measurement process into many small temporal steps, where the detector scans across different positions in the diffraction pattern over time. Each detector element accumulates signal from multiple positions rather than being exposed to one intense peak continuously, distributing the dose and preventing detector damage while maintaining measurement precision.
3Measurement precision
If the dose per pixel is increased to reduce pile-ups, then counting accuracy improves, but radiation damage to specimen increases
Solution Approach 1:
The scanning motion creates periodic sampling of the diffraction pattern at low dose rates, allowing accurate particle counting without pile-ups. By distributing the total dose over many temporal samples rather than concentrating it in one exposure, the patent achieves high counting accuracy while keeping the instantaneous dose below the pile-up threshold.
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 method enables the recording of high-resolution diffraction patterns with improved signal quality at low doses, reducing detector damage and resolving miscounts, thereby enhancing structural resolution in organic and inorganic samples.
Implementation Method 1
record a diffraction pattern of the irradiated portion of the specimen
Data Source
AI summary
Techniques of using a Transmission Charged Particle Microscope for diffraction pattern detection are disclosed. An example method including irradiating at least a portion of a specimen with a charged particle beam, using an imaging system to collect charged particles that traverse the specimen during said irradiation, and to direct them onto a detector configured to operate in a particle counting mode, using said detector to record a diffraction pattern of said irradiated portion of the specimen, recording said diffraction pattern iteratively in a series of successive detection frames, and during recording of each frame, using a scanning assembly for causing relative motion of said diffraction pattern and said detector, so as to cause each local intensity maximum in said pattern to trace out a locus on said detector.