Scanning Microscope Moiré Pattern Generation for Large Area Imaging
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Solution Overview
Problem
Scanning Transmission Electron Microscopes (STEM) face challenges in achieving high spatial resolution and accuracy when observing large areas of crystal lattice images due to positional instability and long scanning times, which hinder the ability to maintain image accuracy and observe large areas effectively.
Innovation Solution
A method involving the generation of a two-dimensional moiré pattern by setting virtual lattice points corresponding to the crystal structure's periodicity, using a scanning microscope to detect signals from these points, and generating the moiré pattern based on the detected signals, allowing for high-accuracy and rapid observation of large areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If STEM uses scanning method to observe crystal lattice image, then it can observe multiple signals including HAADF signal all at once, but it takes longer time to acquire a single image compared to TEM
Solution Approach 1:
The patent creates a virtual crystal lattice image by copying the periodic structure information from the actual crystal lattice. Instead of scanning the entire large area to obtain the full image, the system scans only a small reference area, extracts periodicity information, and then generates a virtual image of the large area by replicating this periodic pattern. This copying approach allows rapid acquisition of large-area crystal lattice images while maintaining the ability to observe multiple signals simultaneously through STEM.
2Measurement precision
If STEM maintains high spatial resolution for scan steps, then crystal lattice image can be observed with high accuracy, but scanning time becomes proportional to scanning area and increases by 100 times when scale changes by 10 times
Solution Approach 1:
The patent segments the imaging process into two distinct stages: (1) scanning a small reference area to extract periodicity information with high spatial resolution, and (2) generating the full large-area image by replicating this periodic pattern. This segmentation allows the system to maintain high measurement precision in the reference area while avoiding the time penalty of scanning the entire large area at the same resolution. The virtual image generation step rapidly creates the complete image without requiring proportional scanning time.
3Measurement precision
If STEM scans large area with high spatial resolution, then image accuracy can be maintained, but positional instability of about 1 nm per minute causes accuracy to be insufficient when required accuracy is less than one atomic lattice distance
Solution Approach 1:
The patent performs preliminary scanning of a small reference area to extract periodicity information before generating the full large-area image. By capturing the periodic structure characteristics in advance, the system creates a template that can be replicated across the entire large area without requiring continuous high-precision scanning. This preliminary action ensures that the periodicity information is captured with high accuracy while minimizing the time the system spends in high-precision scanning mode, thereby reducing the impact of positional instability.
4Illumination intensity
If STEM observes crystal lattice image of 50 nm square area, then enough signal intensity can be obtained, but it takes 1 minute or more which causes large shift of the image
Solution Approach 1:
The patent obtains sufficient signal intensity by scanning a small reference area to capture the periodicity characteristics, then rapidly generating the full large-area image through virtual replication. This copying approach ensures that the signal intensity required for clear crystal lattice observation is achieved in the reference area, while the subsequent virtual image generation occurs so rapidly that no additional signal accumulation time is needed, thereby avoiding image shift due to positional instability during extended scanning.
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 the STEM to observe large areas with high spatial resolution in a short time, overcoming positional instability and maintaining image accuracy, while also allowing for the detection of slight changes in periodicity, thereby improving the observation of crystal lattice structures.
Implementation Method 1
a moiré pattern generating unit for generating a two-dimensional moiré pattern of the crystal structure, based on the detected signals
Data Source
AI summary
A method for taking a crystal lattice moiré pattern of a crystal structure using a scanning microscope, and the scanning microscope implementing the method, arranges multiple virtual lattice points periodically corresponding to the crystal structure and an orientation thereof, on a scan plane of the crystal structure, detects signals from the multiple virtual lattice points, generated by an incident probe of the scanning microscope, and generates data of the crystal lattice moiré pattern, based on the detected signals.