Segmented Detector Alignment in STEM Using Image Deviation
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Solution Overview
Problem
Conventional methods for measuring the directions of detector segments in a scanning transmission electron microscope (STEM) are time-consuming and require additional hardware, such as a CCD camera, and become burdensome when the scanning direction changes.
Innovation Solution
A measurement method that defocuses the STEM image to measure the directions of detector segments relative to the image deviation, allowing for easy alignment without the need for a CCD camera or other hardware, using the relative positional deviation between differently focused images to determine segment orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to measure detector segment directions, then measurement accuracy can be achieved, but the measurement process becomes time-consuming and requires additional hardware
Solution Approach 1:
The patent extracts the measurement function from external hardware (CCD camera) and integrates it into the existing segmented detector system. By using the segmented detector itself to capture defocused images, the measurement process no longer requires separate measurement devices, thereby reducing time and hardware requirements while maintaining measurement accuracy
Solution Approach 2:
The segmented detector is given multiple functions: it serves both as the primary electron detection device for STEM imaging and as a measurement device for determining detector segment directions. This multi-functionality eliminates the need for dedicated measurement hardware and reduces overall measurement time
2Measurement precision
If conventional methods with CCD camera are used, then detector segment directions can be measured, but device complexity increases
Solution Approach 1:
The patent removes the CCD camera from the measurement system and utilizes only the segmented detector and its control unit. This extraction of unnecessary components simplifies the device while preserving the essential measurement capability
Solution Approach 2:
The segmented detector and control unit perform both STEM imaging and direction measurement functions, eliminating the need for separate measurement hardware and thereby reducing device complexity
3Ease of operation
If conventional alignment methods are used, then detector segments can be aligned to STEM image, but the process becomes burdensome when scanning direction changes
Solution Approach 1:
The patent performs preliminary measurement of detector segment directions using defocused images, which establishes a reference framework that remains valid even when scanning directions change. This preliminary action eliminates the need for repeated alignment procedures
Solution Approach 2:
The control unit automatically adjusts detector segment orientations based on feedback from the measured directions and scanning direction information. This automated feedback loop maintains alignment efficiency without manual intervention when scanning directions change
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
Enables efficient and accurate measurement of detector segment directions relative to STEM images, reducing the complexity and time required for alignment and eliminating the need for additional hardware, while allowing for real-time adjustment of segment orientations.
Implementation Method 1
an electron beam EB is focused onto the surface of a sample S by an illumination lens system 102
Implementation Method 2
The camera length is adjusted by an imaging lens system 104 for the electron beam EB transmitted through the sample S
Implementation Method 3
the beam is detected by the segmented detector, 106
Data Source
AI summary
A measurement method capable of easily measuring the directions of detector segments of a segmented detector relative to a scanning transmission electron microscope (STEM) image is provided. The measurement method is for use in an electron microscope equipped with the segmented detector having a detection surface divided into the detector segments. The measurement method is used to measure the directions of the detector segments relative to the STEM image. The method involves defocusing the STEM image to thereby cause a deviation of the STEM image and measuring the directions of the detector segments relative to the STEM image from the direction of the deviation of the STEM image (step S11).