TEM Projector Lens Switching for Artefact-Free EELS
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Solution Overview
Problem
Traditional transmission electron microscopes (TEMs) face challenges in achieving high energy resolution and large energy range EELS measurements due to optical aberrations and limited collection angles, which result in artefacts and compromised signal quantification.
Innovation Solution
The transmission charged particle microscope is designed to operate in at least two modes, allowing for different settings of the final projector lens to optimize the imaging system for various EELS modes, such as ultra-high resolution and low-HT EELS, thereby reducing experimental artefacts and enhancing energy resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional TEM optics are used for EELS measurements, then the system is simple and easy to operate, but optical aberrations and limited collection angles result in artefacts and compromised energy resolution
Solution Approach 1:
The patent implements a dynamic optical system where the projector lens excitation can be switched between at least two different settings (first and second modes). This allows the microscope to adapt its optical configuration based on the specific EELS measurement requirements, enabling high energy resolution when needed while maintaining operational flexibility.
Solution Approach 2:
The invention changes the excitation parameter of the projector lens to achieve different operational modes. By adjusting the lens excitation between two distinct settings, the system optimizes the transfer of electron energies and scattering angles to the EELS spectrometer, thereby improving energy resolution and extending energy range without permanent structural modifications.
2Measurement precision
If the projector lens excitation is changed to optimize for high energy resolution, then energy resolution improves, but the system can only operate in one mode at a time
Solution Approach 1:
The system employs dynamic switching between at least two operational modes by changing the projector lens excitation setting. This allows the microscope to be adapted for different EELS measurement requirements (e.g., ultra-high resolution versus low-HT EELS) while maintaining the ability to switch between modes as needed.
Solution Approach 2:
The patent creates a multi-functional optical system where a single microscope configuration can perform multiple EELS measurement types. By implementing at least two different projector lens excitation settings, the system achieves universality, allowing it to handle both high energy resolution measurements and extended energy range measurements without requiring separate dedicated systems.
3Quantity of substance
If large collection angles are used for EELS measurements, then more signal is collected, but optical aberrations increase and create artefacts
Solution Approach 1:
The invention addresses the artefact problem by changing the projector lens excitation parameter between different modes. This parameter adjustment optimizes the optical transfer function for large collection angles, allowing high signal intensity to be collected while minimizing the formation of artefacts that would otherwise compromise spectra quality.
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 faithful transfer of electron energies and scattering angles from the diffraction plane to the EELS spectrometer, even at large collection angles and high energy losses, resulting in artefact-free EELS spectra with improved energy resolution and extended energy range.
Implementation Method 1
Some of the electrons will undergo inelastic scattering, which means that they lose energy and maybe have their paths slightly deflected
Implementation Method 2
a final projector lens, which is an imaging lens, arranged for forming and imaging a diffraction pattern of the sample
Implementation Method 3
The amount of energy loss can be measured via an electron spectrometer and interpreted in terms of what caused the energy loss
Data Source
AI summary
The invention relates to a transmission charged particle microscope comprising a charged particle beam source for emitting a charged particle beam, a sample holder for holding a sample, an illuminator for directing the charged particle beam emitted from the charged particle beam source onto the sample, and a control unit for controlling operations of the transmission charged particle microscope. As defined herein, the transmission charged particle microscope is arranged for operating in at least two modes that substantially yield a first magnification whilst keeping said diffraction pattern substantially in focus. Said at least two modes comprise a first mode having first settings of a final projector lens of a projecting system; and a second mode having second settings of said final projector lens.