Arc-Shaped Wien Filter Layout for Uniform Deflection Fields
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Solution Overview
Problem
Existing Wien filters face challenges in achieving a compromise between structural simplification and uniformity of the deflection field distribution, leading to issues with off-axis aberration and field uniformity in charged particle beam imaging apparatuses.
Innovation Solution
A Wien filter design featuring an electrostatic deflector with arc-shaped electrodes and a magnetic deflector with arc-shaped magnetic poles, both with radial protrusions to minimize off-axis aberration, and a regulator system to optimize the distribution of electric and magnetic fields, ensuring orthogonality and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional Wien filter structures are used, then the structural design is simplified, but the uniformity of the deflection field distribution deteriorates
Solution Approach 1:
The patent introduces a regulator component with non-uniform structure design, where different regions of the regulator have different shapes and positions to locally adjust the field distribution. This allows the deflection field to achieve better uniformity across the beam path without requiring complete redesign of the entire filter structure.
Solution Approach 2:
The patent modifies geometric parameters of the regulator (such as its position, shape, and dimensions) to optimize the deflection field uniformity. By adjusting these parameters, the system achieves improved field distribution while maintaining the overall simplified structure of the Wien filter.
2Device complexity
If conventional Wien filter structures are used, then the structural design is simplified, but off-axis aberration increases
Solution Approach 1:
The regulator is designed with specific local features (such as protrusions or varying cross-sections) that target the correction of off-axis beam paths. These local structural modifications compensate for aberrations experienced by off-axis particles without complicating the overall filter design.
3Manufacturing precision
If field uniformity is improved through complex regulator design, then the uniformity of the deflection field is enhanced, but the structural design becomes more complex
Solution Approach 1:
The regulator acts as an intermediary component between the electrostatic and magnetic deflectors. It mediates the interaction between these two fields to achieve uniform deflection without requiring complex modifications to either the electrostatic or magnetic deflector structures themselves.
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 enhances the uniformity of the deflection field, reduces off-axis aberration, and simplifies the structural design, improving the imaging quality and efficiency of charged particle beam imaging apparatuses.
Implementation Method 1
the at least one pair of electrodes being configured to generate respective electric fields by cooperation of the respective two electrodes in each pair of the at least one pair of electrodes, in the condition of respective bias voltages applied individually thereon
Implementation Method 2
the at least one pair of magnetic poles being configured to generate respective magnetic fields by cooperation of respective two magnetic poles in each pair of the at least one pair of magnetic poles
Implementation Method 3
a Wien filter which uses composite (typically orthogonal) electric field and magnetic field to deflect the secondary charged particles
Data Source
AI summary
A Wien filter and a charged particle beam imaging apparatus are provided. The Wien filter Wien filter, including a Wien filter body which includes: an electrostatic deflector, including at least one pair of electrodes, respective two electrodes in each pair of which are opposite to each other, each electrode including an electrode body constructed in an arc-shaped form, and respective electrode bodies of respective two electrodes in each pair of the at least one pair of electrodes being arranged concentrically with and opposite to each other in a diameter direction, and the at least one pair of electrodes being configured to generate respective electric fields by cooperation of the respective two electrodes in each pair of the at least one pair of electrodes, in the condition of respective bias voltages applied individually thereon; and a magnetic deflector, including at least one pair of magnetic poles, respective two magnetic poles in each pair of which are opposite to each other, each magnetic pole including a magnetic pole body constructed in an arc-shaped form, and respective magnetic pole bodies of respective two magnetic poles in each pair of the at least one pair of magnetic poles being arranged concentrically with and opposite to each other in the diameter direction, and the magnetic pole bodies of the at least one pair of magnetic poles in the magnetic deflector and the electrode bodies of the at least one pair of electrodes in the electrostatic deflector being arranged concentrically and spaced apart from each other in a circumferential direction, and the at least one pair of magnetic poles being configured to generate respective magnetic fields by cooperation of respective two magnetic poles in each pair of the at least one pair of magnetic poles; a resultant electric field formed collectively by all of the respective electric fields is perpendicular to a resultant magnetic field formed collectively by all of the respective magnetic fields; and each electrode is also provided with a respective first protrusion extending radially inwards from a radial inner side of the respective electrode body thereof, and each magnetic pole is also provided with a second protrusion extending radially inwards from a radial inner side of the respective magnetic pole body thereof.