EELS Harmonic Noise Correction Circuit
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Solution Overview
Problem
Electron energy loss spectrometry in TEMs is limited by noise from power line frequencies and their harmonics, which affect resolution and stability, particularly due to electromagnetic fields and ground currents, and existing correction methods are insufficient for high-resolution systems.
Innovation Solution
An electron energy loss spectrometer with a power line noise correction circuit that generates and adjusts both a fundamental frequency and a harmonic correction signal, such as the third harmonic, to be applied to the bending magnet and drift tube, using a microcontroller and digital converters to sample and process the AC power line voltage, allowing for independent phase and amplitude adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the correction signal amplitude and phase are fixed, then the correction system is simple, but it cannot adapt to varying power line conditions and optimize noise reduction
Solution Approach 1:
The correction system dynamically adjusts the amplitude and phase of correction signals for both the fundamental frequency and third harmonic based on real-time power line conditions, transforming the static correction approach into a dynamic adaptive system
Solution Approach 2:
The system changes the parameters (amplitude and phase) of the correction signals applied to the bending magnet based on sampled power line voltage characteristics, allowing optimization of noise reduction under varying operating conditions
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 effectively corrects for noise associated with AC power sources, improving the stability and resolution of electron energy loss spectrometry by actively managing both fundamental and harmonic frequency components, thereby enhancing the quality of the energy-loss spectrum.
Implementation Method 1
A bending magnet 13 bends the electron beam over an angle, typically 90 degrees, to introduce energy dispersion
Implementation Method 2
an electromagnetic field sensing sampling circuit for indirectly sensing AC power line noise in the vicinity of the EELS
Data Source
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AI summary
Electron Energy Loss Spectrometer including a correction circuit for fundamental and third harmonic line noise is described. Various circuits for creating the correction signals are also described. A method of correcting for fundamental and third harmonic line noise is also described.