Electron Diffraction Pattern Indexing With Dynamic Template Matching
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Solution Overview
Problem
Conventional methods for indexing electron diffraction patterns, such as Hough transform and dictionary indexing, face challenges with poor diffraction pattern quality due to high defect density, low electron dose, nanocrystalline structures, and non-crystalline regions, leading to inefficient and time-consuming processing.
Innovation Solution
The dynamic template matching method generates simulated templates on-the-fly, using master datasets and geometric calibration data to efficiently match experimental patterns, reducing computational resource requirements and eliminating the need for pre-calculated libraries, allowing for flexible orientation spacing and improved processing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dictionary indexing is used to improve indexing accuracy for poor diffraction patterns, then measurement precision is improved, but productivity deteriorates due to hours or days of processing time
Solution Approach 1:
The patent pre-calculates and stores intensity ratios for multiple crystallographic orientations in a lookup table before actual indexing. During indexing, the system retrieves pre-computed intensity ratios and compares them with experimental patterns, eliminating the need for time-consuming real-time simulations while maintaining accurate phase identification and orientation determination
Solution Approach 2:
The patent segments the complex indexing problem into distinct components: (1) pre-computation of intensity ratios for each orientation, (2) storage in organized lookup tables, and (3) rapid retrieval and comparison during indexing. This segmentation allows each component to be optimized independently, achieving both accuracy and speed
2Adaptability or versatility
If a comprehensive dictionary of simulated patterns is created to handle all crystal orientations, then adaptability is improved, but device complexity increases due to storage requirements for millions of patterns
Solution Approach 1:
The patent changes the approach from storing complete simulated diffraction patterns to storing only essential intensity ratio parameters for each crystallographic orientation. This parameter reduction transforms the data structure from millions of complex images to a compact numerical lookup table, dramatically reducing storage requirements while preserving the ability to handle all orientations
Solution Approach 2:
The patent extracts only the critical intensity ratio information from complete simulated diffraction patterns. By taking out just the essential comparative intensity data needed for indexing and discarding redundant spatial and intensity distribution details, the system achieves comprehensive orientation coverage with minimal storage
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 significantly enhances indexing speed while maintaining accuracy, reducing processing time from hours to seconds, and improves usability by efficiently using computational resources and adapting to varying signal-to-noise ratios.
Implementation Method 1
an electron beam is focused onto a point on the surface of a sample. An electron detector is used to collect an image of the resulting diffraction pattern from that point
Implementation Method 2
the scattered electrons are monitored by a detector
Data Source
AI summary
A method of indexing an electron diffraction pattern comprises obtaining a number of experimental electron diffraction patterns at a low resolution from a sample of material using a detector. A master simulation dataset is loaded into the primary memory of a computer system for each phase of the sample material. A simulated template is generated at the low resolution in the primary memory of the computer by using the master simulation dataset from the primary memory wherein the simulated template represents a simulated electron diffraction pattern for a nominal crystallographic orientation. The simulated template is compared with the experimental electron diffraction pattern so as to generate a corresponding similarity measure which is stored. The process is repeated for all crystallographic orientations using crystallographic orientation intervals, and for each phase and each location on the sample. The similarity measures stored in step f are then analysed so as to select at least one resultant indexed phase and orientation for each location. A system configured to perform the method is also provided.