Electron Gun Aberration Reduction via Electrostatic Lens Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electron guns employing Butler type lenses suffer from large aberration, which limits their luminance and resolution, and the combination with magnetic field lenses complicates the structure and alignment, affecting the stability and operability of electron microscopes and beam application devices.
Innovation Solution
An electron gun design featuring a needle-like field emission electron source, an acceleration electrode, a control electrode with a larger aperture diameter, and a control section to manage the potential applied to the control electrode, generating a compact electric field and minimizing aberration through a short focal length electrostatic lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Butler type electron lenses are used in the electron gun, then the structure is streamlined and size is reduced, but the aberration becomes large which limits luminance and resolution
Solution Approach 1:
The electron gun is divided into multiple electrode sections (control electrode, acceleration electrode, focus electrode) with distinct functions. Each electrode is optimized independently to control specific aspects of electron beam formation, allowing aberration reduction while maintaining structural efficiency
Solution Approach 2:
Different regions of the electron gun employ different electrode configurations and potentials. The control electrode near the electron source uses a larger aperture diameter to reduce spherical aberration, while downstream electrodes are optimized for focusing and acceleration, creating locally optimized conditions throughout the beam path
2Manufacturing precision
If magnetic field lens is combined with electrostatic lens to reduce aberration, then luminance and resolution are improved, but the structure becomes complicated and alignment becomes difficult
Solution Approach 1:
Multiple electrostatic lens functions (control, acceleration, focus) are merged into a compact sequence of electrodes within the electron gun. This integration achieves aberration control through electrostatic fields alone, eliminating the need for separate magnetic field lens systems and their associated alignment complexities
Solution Approach 2:
The electrostatic lens system performs multiple functions simultaneously: the control electrode manages field emission and initial beam formation, the acceleration electrode provides beam acceleration, and the focus electrode controls beam convergence. This multi-functionality reduces the need for separate dedicated components
3Device complexity
If conventional Butler type electron gun is used, then structure is compact, but the virtual focal position fluctuates when acceleration voltage changes, affecting stability and operability
Solution Approach 1:
The electron gun employs dynamic control of electrode potentials to maintain stable virtual focal position across varying acceleration voltages. The control electrode potential is adjusted in response to acceleration voltage changes, dynamically compensating for focal position drift and maintaining operational stability
Solution Approach 2:
The control electrode serves as a feedback mechanism that responds to changes in acceleration voltage by adjusting its potential accordingly. This feedback control stabilizes the virtual focal position, ensuring consistent beam formation and imaging performance across different 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 design reduces aberration and stabilizes the virtual focal position, enabling high-resolution imaging with enhanced luminance and operability, even under lower acceleration voltages, and allows for a more compact and streamlined electron gun structure.
Implementation Method 1
a needle-like electron source acting as a field emission type electron source
Implementation Method 2
an acceleration electrode to accelerate electrons emitted from the electron source
Implementation Method 3
generating a compact electric field and minimizing aberration through a short focal length electrostatic lens
Data Source
AI summary
The purpose of the present invention is to provide a charged particle gun using merely an electrostatic lens, said charged particle gun being relatively small and having less aberration, and to provide a field emission-type charged particle gun having high luminance even with a high current. This charged particle gun has: a charged particle source; an acceleration electrode that accelerates charged particles emitted from the charged particle source; a control electrode, which is disposed further toward the charged particle source side than the acceleration electrode, and which has a larger aperture diameter than the aperture diameter of the acceleration electrode; and a control unit that controls, on the basis of a potential applied to the acceleration electrode, a potential to be applied to the control electrode.