Electron Microscope Aberration Correction With Integrated Multipole Fields
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Solution Overview
Problem
Existing electron microscopes face challenges in achieving high-resolution imaging due to uncorrected aberrations such as spherical, chromatic, and high-order aberrations, which hinder the acquisition of clear and detailed images.
Innovation Solution
An aberration correcting device incorporating a multipole system with hexapole, octupole, and transfer lens systems that generate specific electromagnetic fields to superpose quadrupole and octupole fields, correcting aberrations through a combination of hexapole fields and transfer lens systems to cancel positive aberrations with negative ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tandem system of spherical aberration corrector and chromatic aberration corrector is used, then both spherical and chromatic aberrations can be corrected, but the device becomes large and complex
Solution Approach 1:
The patent combines the spherical aberration corrector and chromatic aberration corrector into a single integrated device. The hexapole field generating unit corrects spherical aberration while the quadrupole field generating unit corrects chromatic aberration, both operating within the same physical structure rather than as separate tandem systems.
Solution Approach 2:
The integrated aberration corrector performs multiple functions simultaneously: it generates hexapole fields for spherical aberration correction and quadrupole fields for chromatic aberration correction within a single device, making the system multi-functional and eliminating the need for separate dedicated correctors.
2Measurement precision
If high-order aberration correction is added to achieve higher resolution, then imaging resolution improves, but the device structure becomes more complex
Solution Approach 1:
The patent merges high-order aberration correction capabilities into the existing integrated aberration corrector structure. The octupole field generating unit is incorporated alongside the hexapole and quadrupole units, allowing high-order aberration correction without requiring entirely separate additional systems.
Solution Approach 2:
The aberration corrector employs a composite field structure combining multiple multipole fields (quadrupole, hexapole, octupole) generated by different units within the same device. This composite approach enables correction of multiple aberration types simultaneously while maintaining a unified device architecture.
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 device effectively corrects spherical, chromatic, and high-order aberrations, enabling high-resolution imaging in electron microscopes by reducing aberrations and allowing for a more compact device design compared to tandem systems.
Implementation Method 1
a first multipole which generates a hexapole field; a second multipole which generates a hexapole field with a polarity opposite to a polarity of the hexapole field generated by the first multipole
Implementation Method 2
a third multipole which is disposed between the first multipole and the second multipole and generates an octupole field
Implementation Method 3
the first transfer lens system including a plurality of fourth multipoles which generate a field in which an electromagnetic-field superposed quadrupole field and an octupole field are superposed; and the second transfer lens system including a plurality of fifth multipoles which generate a field in which an electromagnetic-field superposed quadrupole field and an octupole field are superposed
Data Source
AI summary
An aberration correcting device includes a first multipole which generates a hexapole field; a second multipole which generates a hexapole field with a polarity opposite to a polarity of the hexapole filed generated by the first multipole; a third multipole which is disposed between the first multipole and the second multipole and generates an octupole field; a first transfer lens system disposed between the first multipole and the third multipole; and a second transfer lens system disposed between the third multipole and the second multipole. The first transfer lens system includes a plurality of fourth multipoles which generate a field in which an electromagnetic-field superposed quadrupole field and an octupole field are superposed; and the second transfer lens system includes a plurality of fifth multipoles which generate a field in which an electromagnetic-field superposed quadrupole field and an octupole field are superposed.