Electron Microscope X-ray Dead Time Correction
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Solution Overview
Problem
Current methods for measuring characteristic X-ray spectra and electron energy loss spectra are time-consuming, leading to weak signal strength and poor energy resolution, making it difficult to obtain quantitative element images and spectra with high S/N ratios and energy precision.
Innovation Solution
An electron microscope system that corrects for dead time in characteristic X-ray detection and integrates multiple electron energy loss spectra, including core loss and zero loss peaks, to enhance signal strength and energy resolution, allowing for simultaneous measurement of spectra at the same sample position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electron beam scans the sample for dozens of minutes to several hours to enhance signal strength, then the S/N ratio of the characteristic X-ray spectrum improves, but the measurement time becomes excessively long
Solution Approach 1:
The patent combines simultaneous measurement of characteristic X-ray spectra and electron energy loss spectra at the same sample position. By merging these two measurement processes into a single operation, the system achieves both spectral measurements without requiring separate scanning operations, thereby reducing total measurement time while maintaining signal quality through the complementary nature of the two techniques.
Solution Approach 2:
The patent applies dead time correction to account for the relationship between X-ray emission amount and detection efficiency. By dynamically adjusting for dead time effects based on measured X-ray intensities, the system can accurately quantify elements even when using shorter measurement times, effectively decoupling measurement duration from measurement accuracy.
2Measurement precision
If the electron beam irradiation time is adjusted to achieve equal effectual measurement time for each pixel in characteristic X-ray spectroscopy, then the element distribution image quality improves, but the electron energy loss spectrum signal strength becomes inconsistent across pixels
Solution Approach 1:
The patent uses the characteristic X-ray spectrum measurement as a feedback mechanism to determine the actual electron beam irradiation time for each pixel. This irradiation time information is then applied to correct the electron energy loss spectrum measurements, ensuring that quantitative analysis can be performed accurately even when irradiation times vary across different pixels due to dead time effects.
3Adaptability or versatility
If the energy range is expanded to measure multiple elements simultaneously in electron energy loss spectroscopy, then the energy resolution per element decreases
Solution Approach 1:
The patent combines electron energy loss spectroscopy with characteristic X-ray spectroscopy to achieve complementary elemental analysis. While EELS provides information about light elements and bonding characteristics, X-ray spectroscopy covers heavier elements, together offering comprehensive multi-element analysis without requiring the EELS spectrometer to scan through the entire energy range, thereby maintaining energy resolution.
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 the measurement of quantitative element images with high S/N ratios and electron energy loss spectra with high energy resolution, reducing measurement time and improving precision.
Implementation Method 1
a characteristic X-ray spectrometer for detecting a characteristic X-ray emitted from the sample by irradiation of the electron beam
Implementation Method 2
The electron energy loss spectrometer detects an inelastic scattering electron beam
Data Source
AI summary
An object of the present invention relates to measurement of a quantitative element image with a high S/N ratio and measurement of an electron energy loss spectrum with high energy precision and energy resolution. The present invention relates to measurement of a characteristic X-ray spectrum obtained by correcting dead time due to excessive X rays and measurement of an electron energy loss spectrum obtained by correcting energy based on a zero loss peak in the case where the characteristic X-ray spectrum and the electron energy loss spectrum are measured by irradiating one irradiation position on a sample with an electron beam for a predetermined time while scanning the surface of the sample to observe a Z-contrast image. According to the present invention, it becomes possible to measure a quantitative element image with a high S/N ratio by a characteristic X ray, an element image with a high S/N ratio by an electron energy loss spectrum and a high energy resolution spectrum.