Optical Fiber Bundle for STEM Detector Segmentation
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Solution Overview
Problem
Conventional scanning transmission electron microscopes struggle to precisely obtain angular and directional information of scattered electrons due to averaging effects, limiting detector segment configurations and positional control between diffraction patterns and detectors.
Innovation Solution
The use of optical fibers grouped into fiber bundles allows for flexible detection region definition and easy positional control between diffraction patterns and detectors, enabling precise angular and directional information capture through rotatable and arbitrarily shaped fiber bundles with photomultipliers or avalanche photodiodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional light guides are used to transmit electron images to detectors, then the system structure is simple, but it is impossible to split the detector into multiple segments and control the positional relationship between diffraction pattern and detector segments
Solution Approach 1:
The optical fiber bundle is divided into multiple independent fiber groups, where each fiber group corresponds to a specific detector segment. This segmentation allows the detector to be divided into multiple functional regions while maintaining independent control over each segment's positional relationship with the diffraction pattern.
Solution Approach 2:
The patent introduces a rotatable mechanism that allows the optical fiber bundle to be rotated around the electron beam axis. This dynamic adjustment capability enables precise control of the positional relationship between the diffraction pattern and detector segments, transforming a static system into a dynamically adjustable one.
2Measurement precision
If magnetic lenses or detector rotation are used to control positional relationship, then some positional adjustment is possible, but complete positional control is quite difficult to accomplish
Solution Approach 1:
The patent replaces complex magnetic lens systems and detector rotation mechanisms with a simpler optical fiber bundle rotation mechanism. By rotating the fiber bundle mechanically in a controlled manner, precise positional control is achieved without the complexity of magnetic field adjustments or detector repositioning.
3Measurement precision
If conventional detectors are used, then the device structure is simple, but angular distribution information of scattered electrons cannot be precisely obtained due to averaging effects
Solution Approach 1:
By dividing the optical fiber bundle into multiple independently controllable fiber groups, each group can detect electron scattering in a specific angular range. This segmentation eliminates the averaging effect of conventional detectors, allowing precise measurement of angular distribution by analyzing signals from each segment separately.
Solution Approach 2:
The patent adds angular dimensionality to the detection system by arranging fiber groups at different angular positions around the electron beam. This transforms a one-dimensional detection approach into a multi-dimensional system capable of capturing complete angular distribution information.
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 solution enables high-resolution, high-sensitivity imaging by preventing optical loss and allowing for precise control of detector segments, facilitating advanced imaging techniques like atomic-resolution STEM and improved compositional analysis.
Implementation Method 1
a scintillator for converting signals representing the electrons transmitted through the specimen into optical signals
Implementation Method 2
The optical fibers are grouped into plural fiber bundles which are connected with respective ones of the segments of the photodetector
Implementation Method 3
a photodetector for detecting the optical signals emanating from the scintillator
Data Source
AI summary
A scanning transmission electron microscope using optical fibers as optical guiding media. The microscope obtains a high-angle scattering image or a dark-field image from electrons transmitted through a specimen. A scintillator converts electrons transmitted through the specimen into optical signals. The optical fibers couple outputs from the scintillator to the photodetector segments. The connections of the fibers with the photodetector segments are formed into arbitrary shapes.