TEM Corrector Multipole Coating for Johnson Noise Reduction
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Solution Overview
Problem
Thermal magnetic field noise, also known as Johnson noise, from conductive parts in electron microscopy systems causes decoherence and limits resolution, particularly in chromatic aberration correctors, and current cooling solutions are expensive and impractical for widespread implementation.
Innovation Solution
The use of an optical element with an inner core made of an electrically isolating material and an outer coating of an electrically conductive material, where the product of the coating thickness and conductivity is less than 0.01 Ω−1, significantly reduces Johnson noise generation by at least an order of magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If cooling systems (liquid nitrogen, heat pipes, cooling rods) are used to reduce thermal magnetic field noise, then thermal magnetic field noise is reduced, but device complexity and cost increase significantly
Solution Approach 1:
The harmful thermal magnetic field noise is extracted and isolated from the main system by removing the conductive material that generates it. The electrostatic multipole components are designed without conductive materials, extracting the noise source from the corrector system while maintaining the necessary electrostatic field generation function.
Solution Approach 2:
The invention replaces expensive, complex cooling systems with a simple, inexpensive material selection approach. By choosing non-conductive materials for the electrostatic multipole components, the system achieves noise reduction without requiring costly cooling infrastructure, making the solution economically viable for widespread implementation.
2Power
If conductive materials are used in electrostatic multipoles, then electrostatic field generation is effective, but thermal magnetic field noise increases
Solution Approach 1:
The electrical conductivity parameter of the electrostatic multipole components is changed from conductive to non-conductive. This parameter change eliminates the generation of thermal magnetic field noise (Johnson noise) while maintaining the ability to generate effective electrostatic fields for chromatic aberration correction.
Solution Approach 2:
The invention uses composite construction for the electrostatic multipole components, combining non-conductive structural materials with conductive elements only where absolutely necessary for electrical connection. This composite approach minimizes the volume of conductive material, thereby reducing Johnson noise while maintaining electrostatic field generation capability.
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 effectively decreases thermal magnetic field noise by 2× to 3× or more, improving the resolution and practicality of microscopy systems without the need for costly cooling solutions.
Implementation Method 1
Thermal magnetic field noise (Johnson noise) from magnetic and non-magnetic conductive parts close to the electron beam recently has been identified as a reason for decoherence in electron microscopy systems.
Data Source
AI summary
Systems for reducing the generation of thermal magnetic field noise in optical elements of microscope systems, are disclosed. Example microscopy optical elements having reduced Johnson noise generation according to the present disclosure comprises an inner core composed of an electrically isolating material, and an outer coating composed of an electrically conductive material. The product of the thickness of the outer coating and the electrical conductivity is less than 0.01Ω−1. The outer coating causes a reduction in Johnson noise generated by the optical element of greater than 2×, 3×, or an order of magnitude or greater. In a specific example embodiment, the optical element is a corrector system having reduced Johnson noise generation. Such a corrector system comprises an outer magnetic multipole, and an inner electrostatic multipole. The inner electrostatic multipole comprises an inner core composed of an electrically isolating material and an outer coating composed of an electrically conductive material.