Electron Microscope Light Guide Assembly for Low-Vacuum Detection
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Solution Overview
Problem
Existing electron microscopes face challenges when combining Raman Spectroscopy or Cathodoluminescence detection with electron microscopy in low vacuum environments, as it leads to signal blockage and increased working distances, degrading imaging performance.
Innovation Solution
A scanning electron microscope system is configured with a light guide assembly that includes a mirror with a pressure limiting aperture, allowing for the detection of back scattered and secondary electrons at short working distances, even in low vacuum environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a mirror is positioned between the sample and the electron column pole piece to reflect light, then light collection efficiency is improved, but the ability of electrons to reach the electron column pole piece is significantly reduced, degrading detector efficiency
Solution Approach 1:
The patent repositions the light collection mirror from a position between the sample and electron column pole piece to a position on the side of the sample chamber. This spatial reconfiguration allows the mirror to collect light from the sample without blocking the electron beam path to the pole piece, resolving the contradiction between light collection efficiency and detector efficiency by operating in a different spatial dimension.
Solution Approach 2:
The patent introduces a pressure limiting aperture as an intermediary element that separates the electron beam path from the light collection path. The aperture allows electrons to pass through to the pole piece while enabling the mirror to collect light from the sample, acting as a mediator that enables both functions without direct interference between them.
2Reliability
If a pressure limiting aperture is used to separate high vacuum and low vacuum environments, then electron microscopy performance is improved, but the working distance is increased, degrading imaging performance
Solution Approach 1:
The patent extracts the pressure limiting aperture from a position that increases working distance and relocates it to a position that maintains short working distance. By taking the aperture out of the direct electron beam path and repositioning it in the light path, the system maintains high vacuum performance while avoiding the penalty of increased working distance.
3Productivity
If a mirror with a hole is used to allow electron beam passage, then electron beam transmission is enabled, but the mirror significantly reduces the ability of electrons to reach the electron column pole piece
Solution Approach 1:
The patent removes the mirror from the direct electron beam path between the sample and pole piece. Instead of using a mirror with a hole that compromises electron transmission, the mirror is extracted to a side position where it collects light without interfering with electron beam efficiency, while a separate pressure limiting aperture handles the vacuum separation function.
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 configuration enables efficient Raman Spectroscopy and Cathodoluminescence detection in low vacuum environments without the negative impacts of signal blockage and increased working distances, thereby improving the imaging performance of the electron microscope.
Implementation Method 1
the mirror is configured to reflect light from the sample to a light detector
Implementation Method 2
An electron beam is directed from an electron source, through the aperture, to a sample
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An embodiment of electron microscope system is described that comprises an electron column pole piece and a light guide assembly operatively coupled together. The light guide assembly also includes one or more detectors, and a mirror with a pressure limiting aperture through which an electron beam from an electron source passes. The mirror is also configured to reflect light, as well as to collect back scattered electrons and secondary electrons.