Electron Microscopy Calibration Grid Mapping for Beam-Shift Aberrations
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Solution Overview
Problem
Current electron microscopy techniques face inefficiencies in correcting image aberrations, particularly non-axial aberrations, which limit data collection throughput and require high expertise, affecting the quality and resolution of images, especially in cryo-EM single particle reconstruction.
Innovation Solution
The method involves obtaining electron microscope images of reference grid samples under various optical conditions, applying kernel canonical correlation analysis to determine aberration correction functions, and using these functions to correct aberrations in images, enabling efficient data collection and higher resolution results without the need for extensive microscope alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex microscope alignment procedures are applied to minimize aberrations, then image quality and resolution are improved, but data collection throughput decreases and device complexity increases
Solution Approach 1:
The patent performs preliminary alignment and aberration characterization by imaging a calibration grid at multiple positions before actual data collection. This pre-characterization creates a distortion map that is later used to correct images during high-throughput data collection, eliminating the need for repeated alignment procedures and enabling both high image quality and high throughput
Solution Approach 2:
The patent divides the calibration process into discrete steps: imaging the grid at multiple predetermined positions, characterizing aberrations at each position, and creating a comprehensive distortion map. This segmented approach makes the complex alignment process systematic and automatable, improving both precision and throughput
2Manufacturing precision
If comprehensive microscope alignment is performed to correct non-axial aberrations, then manufacturing precision improves, but device complexity and operational difficulty increase
Solution Approach 1:
The system performs self-alignment by automatically characterizing its own aberrations through imaging the calibration grid at multiple positions. The computer system autonomously determines distortion parameters and generates correction maps without requiring manual intervention or expert alignment procedures, reducing both device complexity and operational difficulty
Solution Approach 2:
The patent changes the parameter being measured from complex wavefront aberrations to simpler geometric distortion parameters by imaging the calibration grid. This parameter transformation simplifies the alignment process while still enabling comprehensive correction of non-axial aberrations through the distortion map
3Productivity
If beam-image shift is used to observe different sample areas, then productivity improves, but image distortion increases requiring repetitive alignment
Solution Approach 1:
The patent performs preliminary characterization of beam-image shift induced distortions by imaging the calibration grid at multiple predetermined positions corresponding to different beam-image shift values. This pre-characterization enables correction of distortions during subsequent high-throughput data collection with beam-image shift, maintaining both productivity and image quality
Solution Approach 2:
The distortion map created from calibration grid images at multiple positions serves as feedback that is applied during data collection to correct images. This feedback mechanism allows the system to maintain high productivity through beam-image shift while compensating for the resulting distortions, preventing quality degradation
Data Source
AI summary
Methods for correcting one or more image aberrations in an electron microscopy image, including cryo-EM images, are provided. The method includes obtaining a plurality of electron microscope (EM) images of an internal reference grid sample having one or more known properties, the plurality of electron microscope images obtained for a plurality of optical conditions and for a plurality of coordinated beam-image shifts. The method may also include, among other features, determining an aberration correction function that predicts aberrations for every point in the imaged area using kernel canonical correlation analysis (KCCA).