Electron Microscope Aberration Measurement Using Segmented Detector
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Solution Overview
Problem
Current methods for aberration measurement in scanning transmission electron microscopes are affected by image drifts, leading to reduced accuracy and longer measurement times due to the need for acquiring multiple bright-field STEM images.
Innovation Solution
An electron microscope equipped with an aperture stop having multiple detection angle-limiting holes and a detector with separate segments to simultaneously capture STEM images from electron beam rays with different detection angles, allowing for aberration calculation using correlation functions and reducing the impact of image drifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple bright-field STEM images are acquired sequentially to measure aberrations, then aberration measurement can be performed without special detectors, but measurement time increases and image drifts reduce accuracy
Solution Approach 1:
The detector is divided into multiple segments, with different segments detecting electron beams at different detection angles simultaneously. This segmentation allows parallel acquisition of multiple images that would otherwise require sequential capture, thereby reducing measurement time while maintaining accuracy through simultaneous detection.
Solution Approach 2:
The patent transitions from sequential temporal acquisition to simultaneous spatial acquisition by arranging detector segments at different angular positions. Multiple detection angles are captured at the same time across different spatial locations of the detector, converting a time-based measurement process into a space-based parallel measurement system.
2Measurement precision
If multiple bright-field STEM images are acquired sequentially to measure aberrations, then aberration measurement can be performed without special detectors, but image drifts during acquisition reduce measurement accuracy
Solution Approach 1:
The detector is divided into multiple segments, with different segments detecting electron beams at different detection angles simultaneously. This segmentation allows parallel acquisition of multiple images that would otherwise require sequential capture, thereby reducing measurement time while maintaining accuracy through simultaneous detection.
Solution Approach 2:
The patent transitions from sequential temporal acquisition to simultaneous spatial acquisition by arranging detector segments at different angular positions. Multiple detection angles are captured at the same time across different spatial locations of the detector, converting a time-based measurement process into a space-based parallel measurement system.
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 enables high-accuracy aberration measurement by reducing the effects of image drifts and shortening measurement time, allowing for precise calculation of aberrations in the illumination lens system.
Implementation Method 1
an aperture stop having a plurality of detection angle-limiting holes for extracting rays of the electron beam having mutually different detection angles from the electron beam transmitted through the sample
Implementation Method 2
a detector for detecting the rays of the electron beam passed through the aperture stop
Data Source
AI summary
There is provided an electron microscope capable of measuring aberration with high accuracy. The electron microscope (100) comprises: an electron beam source (10) for producing an electron beam (EB); an illumination lens system (101) for focusing the electron beam (EB) onto a sample (S); a scanner (12) for scanning the focused electron beam (EB) over the sample (S); an aperture stop (30) having a plurality of detection angle-limiting holes (32) for extracting rays of the electron beam (EB) having mutually different detection angles from the electron beam (EB) transmitted through the sample (S); and a detector (20) for detecting the rays of the electron beam (EB) passed through the aperture stop (30).