Zernike Moment Analysis for Convergent Beam Electron Diffraction
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Solution Overview
Problem
Existing methods for measuring sample thickness and crystal bending distortion using convergent beam electron diffraction in transmission electron microscopes face challenges such as inaccurate mean free path calculations, contamination effects, and the need for large database capacities for image comparison, as well as inefficiencies in processing and rotation operations.
Innovation Solution
The method involves acquiring experimental convergent beam electron diffraction images, calculating Zernike moment intensities, and comparing them with calculated images to determine sample thickness and bending distortion, using Zernike moment intensities and phases to efficiently match and align images without considering rotation influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a database of calculation images is configured for comparing whole two-dimensional images, then measurement precision is improved, but database capacity requirements increase significantly
Solution Approach 1:
The patent extracts essential features from the two-dimensional convergent beam electron diffraction images by calculating Zernike moment intensities. Instead of storing and comparing entire images, only the extracted Zernike moment values are stored in the database and used for comparison. This extraction approach maintains measurement precision while dramatically reducing the data storage requirements.
Solution Approach 2:
The patent applies local quality by focusing computational and storage resources on the most informative aspects of the diffraction images. Zernike moments capture the essential structural information locally, allowing the system to achieve accurate measurements without processing or storing the complete image data, thus optimizing the balance between precision and storage efficiency.
2Measurement precision
If calculation is performed each time to search for coincident images, then measurement accuracy is maintained, but processing efficiency deteriorates
Solution Approach 1:
The patent implements preliminary action by pre-calculating Zernike moment intensities for a series of reference images with known parameters and storing them in a database before actual measurements. During measurement, only comparison operations are performed against the pre-computed database, eliminating the need for repeated full calculations and significantly improving processing efficiency while maintaining accuracy.
Solution Approach 2:
The patent creates a simplified copy of the image information in the form of Zernike moment intensities. These moment values serve as compact representations that capture the essential characteristics needed for accurate comparison, allowing rapid search and matching operations without requiring the original full-resolution images or repeated complex calculations.
3Measurement precision
If image rotation operation is performed for image matching, then measurement completeness is improved, but processing complexity increases
Solution Approach 1:
The patent replaces the mechanical image rotation operation with a mathematical substitution approach. Instead of physically rotating images to achieve alignment, the method uses Zernike moment properties and phase information to directly determine the rotation angle and perform measurements in the transformed domain, eliminating complex rotation operations while maintaining measurement completeness.
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 allows for precise measurement of sample thickness and bending distortion with reduced data processing and storage requirements, improving measurement precision and efficiency by using Zernike moment intensities and phases for image comparison.
Implementation Method 1
convergent beam electron diffraction of a transmission electron microscope
Data Source
AI summary
A physical properties measuring method includes: acquiring an experimental convergent beam electron diffraction image of a sample by using a transmission electron microscope; calculating Zernike moment intensities of the experimental convergent beam electron diffraction image; and comparing the Zernike moment intensities of the experimental convergent beam electron diffraction image with Zernike moment intensities of calculated convergent beam electron diffraction images calculated on changed physical properties of the sample.