TEM Detector Multipoles for Distortion Correction
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Solution Overview
Problem
Current methods for correcting distortions in particle-optical apparatuses, such as Transmission Electron Microscopes (TEMs), require processing each image individually, which limits throughput, especially in applications like tomography, and can introduce artefacts due to pixel displacement.
Innovation Solution
Incorporating multipoles in the detector system and exciting them to correct distortions, allowing for the de-warping of images without the need to process each image separately, by determining and adjusting the multipole excitations based on measured distortions in a pattern with known geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each image is processed individually to correct distortions, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The patent applies preliminary action by measuring and determining the distortion characteristics of the projection system in advance using a calibration object with known geometry. The distortion parameters are stored and then applied to correct multiple images without needing to process each image individually, thus maintaining measurement precision while improving productivity
Solution Approach 2:
The patent uses a calibration object (such as a gold foil with known lattice structure) as a reference copy to establish the distortion map. This reference distortion characteristics are then applied to correct the actual sample images, avoiding the need to process each image separately while maintaining correction accuracy
2Measurement precision
If pixel displacement is used to correct distortions, then measurement precision is improved, but object-generated harmful factors worsen due to artefacts
Solution Approach 1:
The patent replaces the mechanical pixel displacement method with a coordinate transformation approach. Instead of physically moving pixels in the image, the invention uses mathematical transformation of coordinates based on pre-determined distortion parameters, thereby achieving distortion correction without generating processing artefacts
Solution Approach 2:
The patent introduces an intermediary distortion map or transformation function that mediates between the raw distorted images and the corrected images. This intermediary contains the pre-measured distortion characteristics and enables correction through coordinate transformation rather than direct pixel manipulation, reducing artefact generation
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 correction of distortions across multiple images without individual processing, enhancing throughput and reducing artefacts, thereby improving the accuracy and reliability of 3D reconstructions and strain analysis in TEMs.
Implementation Method 1
a detector for detecting the enlarged image, the detector comprising multipoles, wherein the multipoles are excited in such a way that the distortions in the enlarged image are at least partially corrected
Implementation Method 2
the multipoles are excited in such a way that the distortions in the enlarged image are at least partially corrected
Data Source
AI summary
The invention relates to a method for correcting distortions introduced by the projection system (106) of a TEM. As known to the person skilled in the art distortions may limit the resolution of a TEM, especially when making a 3D reconstruction of a feature using tomography. Also when using strain analysis in a TEM the distortions may limit the detection of strain.To this end the invention discloses a detector equipped with multipoles (152), the multipoles warping the image of the TEM in such a way that distortions introduced by the projection system are counteracted. The detector may further include a CCD or a fluorescent screen (151) for detecting the electrons.