Electron Microscope Magnetic Shield Design for Beam Stability
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Solution Overview
Problem
Conventional electron microscopes with an objective lens projecting into the sample chamber space have a weak magnetic shield effect, leading to fluctuations in the environmental magnetic field affecting the electron beam trajectory and focus.
Innovation Solution
An electron microscope design featuring a sample chamber magnetic shield and a tubular objective lens magnetic shield, with strategically positioned holes in the upper plate and shield to house the objective lens and connect it to the sample chamber magnetic shield, enhancing the magnetic shield's effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic shield is disposed along the inner surface of a sample chamber, then the structure is simple and easy to manufacture, but the magnetic shield effect is weak when an objective lens projects into the sample chamber space
Solution Approach 1:
The magnetic shield is divided into two separate components: a sample chamber magnetic shield disposed along the inner surface of the sample chamber, and an objective lens magnetic shield surrounding the objective lens. This segmentation allows each shield to perform its specific function effectively, with the objective lens magnetic shield providing enhanced protection for the lens region where magnetic field interference is most critical.
Solution Approach 2:
A non-magnetic support structure is introduced as an intermediary component to hold the objective lens magnetic shield in position. This support structure connects the objective lens magnetic shield to the sample chamber magnetic shield without creating magnetic interference, enabling the dual-shield configuration while maintaining structural integrity.
2Reliability
If environmental magnetic field fluctuates, then the magnetic field intensity in electron beam trajectory space varies, but with proper magnetic shielding the electron beam position and focus can be maintained
Solution Approach 1:
The magnetic shields are positioned in advance to counteract environmental magnetic field interference before it affects the electron beam. The objective lens magnetic shield is specifically placed to preemptively protect the lens region, while the sample chamber magnetic shield provides preliminary shielding for the sample area, together preventing magnetic field fluctuations from disrupting electron beam trajectory and focus.
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
The design significantly improves the magnetic shield's functionality, reducing magnetic field variations by approximately 20% and maintaining focus despite environmental magnetic field fluctuations.
Implementation Method 1
an objective lens which focuses the electron beam to irradiate a sample with
Implementation Method 2
a sample chamber magnetic shield provided inside the sample chamber; and an objective lens magnetic shield of a tubular shape which surrounds a periphery of the objective lens
Data Source
AI summary
Provided is an electron microscope capable of enhancing a magnetic shield function even though the structure thereof has an objective tens that projects into a sample chamber space. The electron microscope includes: an objective lens (6) which focuses an electron beam to irradiate a sample (4) with; a sample chamber (5) which forms a sample space to contain the sample (4); a sample chamber magnetic shield (7) provided inside the sample chamber (5); and an objective lens magnetic shield (8) of a tubular shape which surrounds the periphery of the objective lens (6). A first and a second hole, which face to each other in a traveling direction of the electron beam, are provided in an upper plate (10) serving as an upper wall of the sample chamber (5) and in an upper shield (9) of the sample chamber magnetic shield (7). The objective lens (6) is held inside the first hole provided in the upper plate (10). A lower end of the objective lens (6) is disposed at a position lower than a lower end of the upper plate (10), and at a position of the second hole provided in the upper shield (9) or at a position near this position. The objective lens magnetic shield (8) is positioned inside the first hole, and a lower end thereof is connected to the upper shield (9).