Charged Particle Microscope Aberration Detection From User Image Data
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Solution Overview
Problem
Charged particle microscopes, such as TEM and STEM, face challenges in aligning and focusing the beam accurately, particularly for novice users, due to issues with astigmatism and the need for time-consuming autofocus and autostigmator procedures, which are slow and require extensive training.
Innovation Solution
A method and system that allow users to acquire and process image data during normal operation, using algorithms like Fast Fourier Transform to determine aberrations, such as focus and astigmatism, without initiating separate autofocus or autostigmator functions, enabling efficient and automatic correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If autofocus and autostigmator functions are used, then aberration correction is automated, but the procedure becomes slow and time-consuming
Solution Approach 1:
The system performs preliminary capture of multiple images at different focus settings and astigmatism corrections during normal operation. These images are stored and later processed to determine optimal aberration corrections without requiring separate autofocus/autostigmator procedures, thus automating the process while minimizing time loss.
Solution Approach 2:
The system uses feedback from analyzing multiple captured images to determine directional sharpness and aberration characteristics. This feedback mechanism enables automatic adjustment of focus and stigmation settings based on quantitative image analysis, resolving the contradiction between automation and time efficiency.
2Ease of operation
If manual stigmation adjustment is performed, then the user has control over astigmatism correction, but the process becomes difficult and requires extensive training
Solution Approach 1:
The system performs self-service by automatically analyzing captured images to determine astigmatism characteristics and optimal stigmation settings. The microscope autonomously processes the images, calculates aberration parameters, and applies corrections without requiring user intervention or expertise in stigmation adjustment, thereby simplifying operation while managing complexity internally.
3Measurement precision
If multiple images are captured for aberration determination, then measurement precision improves, but the processing time increases
Solution Approach 1:
The system captures more images than the minimum single image (excessive action) at different focus and astigmatism settings. This excess image data is processed to determine optimal aberration corrections with high precision. The multiple images provide redundant information that improves measurement accuracy while the systematic processing approach manages the time cost efficiently.
Data Source
AI summary
The invention relates to a method of determining an aberration of a charged particle microscope. The method comprises a step of providing a charged particle microscope that is at least partly operable by a user. Then, a set of image data is obtained with said charged particle microscope. The image data is processed to determine an aberration of said charged particle microscope. According to the invention, said set of image data is actively obtained by a user. In particular, the image data may be obtained during normal operation of the microscope by a user, which may include navigating and/or focusing of the microscope. Thus, the set of image data is acquired by said user, and not by the controller thereof. This allows background processing of an aberration, and aberration correction during use of the charged particle microscope. The invention further relates to a charged particle microscope incorporating the method.