Particle Beam Phase Mask and Multipole Aberration Compensation
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Solution Overview
Problem
High-resolution electron microscopes face limitations due to spherical and chromatic aberrations in electron lenses, which hinder the achievement of optimal resolution, and existing correction methods are complex and costly.
Innovation Solution
A method and system employing a phase mask to spatially modulate the phase of an electron or ion beam, combined with a multipole electromagnetic field, to compensate for aberrations generated by the beam focusing system, allowing for partial or complete correction of spherical and chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electron lenses are used for beam focusing, then beam focusing capability is achieved, but spherical and chromatic aberrations occur that limit resolution
Solution Approach 1:
A phase mask is introduced as an intermediary element between the electron source and the sample. This phase mask modulates the phase of the electron wavefront to compensate for aberrations introduced by the electron lens, thereby improving resolution without requiring complete elimination of the lens system
Solution Approach 2:
The patent changes the phase parameter of the electron beam wavefront through the phase mask. By spatially modulating the phase of the electron wave, the system compensates for aberration effects and achieves improved resolution. The phase modulation pattern is specifically designed to counteract the aberration transfer function of the lens
2Measurement precision
If existing aberration correction methods (quadrupole-octopole, hexapole correctors) are employed, then aberration correction is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the aberration correction function from the complex electromagnetic corrector system and implements it through a simpler phase mask. Instead of using multiple electromagnetic lenses (quadrupole, octopole, hexapole), the correction is achieved by a single phase-modulating element, significantly reducing device complexity
Solution Approach 2:
The patent replaces the mechanical/electromagnetic corrector system with a phase mask that operates on the wave nature of electrons. This substitution uses phase modulation rather than electromagnetic force fields, achieving aberration correction with a simpler system architecture
3Measurement precision
If phase mask is positioned before the beam focusing system, then aberration compensation is achieved, but the phase mask must withstand higher beam intensity and energy
Solution Approach 1:
The phase mask performs preliminary phase modulation of the electron beam before the beam enters the focusing system. By establishing the correct phase relationships early in the beam path, the system achieves aberration compensation while protecting the phase mask from excessive beam intensity that would occur if positioned after focusing
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 approach enhances the resolution of electron microscopes by effectively reducing aberrations, improving image clarity and precision, and is more cost-effective and simpler than existing correction methods.
Implementation Method 1
transmitting the beam through a phase mask selected to spatially modulate a phase of a wavefront of the beam over a cross-section thereof
Implementation Method 2
applying a multipole electromagnetic field to the beam
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3C
AI summary
The present invention relates to a method of manipulating a particle beam propagating along an optical axis, the method comprising: transmitting the beam through a phase mask positioned and a beam focusing system, said phase mask being selected to spatially modulate a phase of a wavefront of the beam over a cross-section thereof, to at least partially compensate for aberration generated by said beam focusing system; and applying a multipole electromagnetic field to the beam so as to also at least partially compensate for said aberrations; wherein said compensation by said multipole electromagnetic field is complementary to said compensation by said phase mask.