Laser Electron Beam Modulation for Spherical Aberration Correction
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Solution Overview
Problem
In electron microscopes, positive spherical aberration occurs during electron beam convergence, reducing resolution and requiring complex control of multiple non-circularly symmetric electron lenses, which is difficult and costly. Additionally, strong magnetic lenses used for objective lenses pose challenges in observing magnetically sensitive targets.
Innovation Solution
An electron beam modulation device that generates round light using a laser light source, polarization conversion, and condensing elements to create a trapping and repulsive potential region, allowing for easy modulation of the electron beam without traditional lenses, and can be controlled to reduce spherical aberration and accommodate magnetically sensitive targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple non-circularly symmetric electron lenses are used to generate negative spherical aberration to cancel positive spherical aberration, then spherical aberration is reduced, but device complexity and control difficulty increase significantly
Solution Approach 1:
The patent replaces the mechanical/electrical control system of multiple electron lenses with an optical system using laser light and a spatial light modulator. The spatial light modulator uses phase modulation to generate negative spherical aberration that cancels the positive spherical aberration from the objective lens, eliminating the need for complex multi-lens electron optical systems while achieving the same aberration correction function.
Solution Approach 2:
The patent changes the approach from adjusting multiple electron lens parameters (positions, outputs, orientations) to modulating a single laser beam's phase distribution. By controlling the phase of laser light incident on the spatial light modulator, the system achieves dynamic control of spherical aberration correction without the complexity of coordinating multiple electron lenses.
2Measurement precision
If strong magnetic field electron lenses are used as objective lenses to achieve high resolution, then imaging resolution is improved, but the ability to observe magnetically sensitive targets deteriorates
Solution Approach 1:
The patent replaces the magnetic field-based electron lens system with an optical modulation system using laser light and a spatial light modulator. This substitution eliminates magnetic fields from the imaging path, allowing observation of magnetically sensitive targets while maintaining high resolution through phase modulation of the electron beam.
Solution Approach 2:
The patent introduces laser light as an intermediary to mediate the focusing and aberration correction functions previously performed by magnetic lenses. The laser light interacts with the spatial light modulator to create phase patterns that modulate the electron beam, achieving lens functions without direct magnetic field exposure of the sample.
3Measurement precision
If multiple electron lenses with precise positioning are used to cancel spherical aberration, then resolution is improved, but manufacturing and installation costs increase
Solution Approach 1:
The patent replaces expensive, precisely manufactured electron lenses with commercially available laser sources and spatial light modulators. The optical components required for phase modulation are more readily manufactured and installed than high-precision electron optical systems, reducing overall manufacturing and installation costs while achieving the same resolution enhancement.
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 modulates the electron beam with ease, reducing spherical aberration and enabling high-resolution imaging of magnetically sensitive targets without the need for complex lens control or high manufacturing costs.
Implementation Method 1
a condensing element configured to condense the laser light passing through the modulation plane. In a focal plane of the condensing element, the laser light is condensed by the condensing element to generate round light
Implementation Method 2
the round light includes a trapping potential region in which electrons included in an electron beam incident on the focal plane are attracted and a repulsive potential region in which the electrons are repelled
Implementation Method 3
a polarization conversion part including a modulation plane configured to modulate a direction of polarization and an intensity of the laser light emitted from the light source such that the direction of the polarization and the intensity have a predetermined directional distribution and a predetermined intensity distribution, respectively
Data Source
AI summary
An electron beam modulation device according to the present disclosure includes a light source configured to emit laser light, a polarization conversion part including a modulation plane configured to modulate a direction of polarization and an intensity of the laser light emitted from the light source, and a condensing element configured to condense the laser light passing through the modulation plane. In a focal plane of the condensing element, a round light is generated that includes a trapping potential region in which electrons included in an electron beam incident on the focal plane are attracted and a repulsive potential region in which the electrons are repelled. The round light has rotational symmetry about an optical axis of the laser light when viewed along the optical axis.