Electron Microscope Aberration Corrector With Hexapole-Octupole Fields
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Solution Overview
Problem
Current aberration correction technologies in electron microscopes are inadequate for effectively addressing high-order aberrations, particularly in achieving high-resolution imaging, as they often require separate devices for spherical and chromatic aberration correction, leading to increased device size and complexity.
Innovation Solution
An aberration correcting device comprising a hexapole field generator, an opposing hexapole field generator, an octupole field generator, and transfer lens systems with superposed quadrupole and octupole fields, which corrects spherical and chromatic aberrations, including fifth-order and six-fold astigmatism, by strategically positioning multipoles and transfer lens systems to cancel aberrations within the electron microscope's image-forming system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate devices are used for spherical and chromatic aberration correction, then correction effectiveness is improved, but device size and complexity increase
Solution Approach 1:
The patent combines spherical aberration correction and chromatic aberration correction into a single integrated corrector device. The corrector includes both a spherical aberration correction unit (with hexapole fields) and a chromatic aberration correction unit (with quadrupole fields) arranged in series, allowing both types of aberration to be corrected simultaneously by one device rather than requiring separate devices.
Solution Approach 2:
The aberration corrector is designed as a multi-functional device that performs multiple correction functions. It can correct spherical aberration, chromatic aberration, and high-order aberrations (such as fifth-order and six-fold astigmatism) within a single system, making the device universal for various aberration types that would otherwise require separate specialized correctors.
2Measurement precision
If high-order aberration correction is implemented, then imaging resolution is improved, but device complexity increases
Solution Approach 1:
The corrector divides high-order aberration correction into segmented functional units. The spherical aberration correction unit and chromatic aberration correction unit are separated into distinct sections with different multipole configurations. This segmentation allows each unit to be optimized for its specific function while working together to achieve comprehensive high-order aberration correction.
Solution Approach 2:
The patent employs composite electromagnetic field structures by superimposing multiple field types (hexapole fields for spherical correction, quadrupole fields for chromatic correction, and octupole fields for high-order correction) within the same optical path. This composite approach enables simultaneous correction of multiple aberration types through the interaction of different field components.
3Reliability
If multiple multipoles are used for comprehensive aberration correction, then correction capability is improved, but manufacturing complexity increases
Solution Approach 1:
The corrector incorporates adjustable and controllable multipole fields that can be dynamically tuned during operation. The hexapole, quadrupole, and octupole fields are designed with adjustable parameters allowing optimization of correction performance for different sample types and imaging conditions, making the complex multi-multipole system adaptable rather than fixed.
Solution Approach 2:
The patent uses transfer lens systems as intermediary components between the different multipole units. These transfer lenses facilitate the optical coupling between the spherical aberration correction unit and the chromatic aberration correction unit, managing the complex interactions between multiple multipoles and enabling modular assembly and adjustment.
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 correction of spherical and chromatic aberrations, reduces device size, and enhances imaging resolution by integrating aberration correction into the electron microscope's optical system, allowing for the cancellation of higher-order astigmatism and chromatic aberrations.
Implementation Method 1
a first multipole which generates a hexapole field
Implementation Method 2
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 3
a third multipole which is disposed between the first multipole and the second multipole and generates an octupole field
Implementation Method 4
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
Implementation Method 5
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
Figure 1
Figure 2~4
Figure 5
AI summary
An aberration correcting device (100) includes: a first multipole which generates a hexapole field (110); a second multipole (120) which generates a hexapole field with a polarity opposite to a polarity of the hexapole filed generated by the first multipole (110); a third multipole (130) which is disposed between the first multipole (110) and the second multipole (120) and generates an octupole field; a first transfer lens system (140) disposed between the first multipole (110) and the third multipole (130); and a second transfer lens system (150) disposed between the third multipole (130) and the second multipole (120), wherein the first transfer lens system (14) includes a plurality of fourth multipoles (142, 143) which generate a field in which an electromagnetic-field superposed quadrupole field and an octupole field are superposed; and the second transfer lens system (150) includes a plurality of fifth multipoles (152, 153) which generate a field in which an electromagnetic-field superposed quadrupole field and an octupole field are superposed.