Electron Microscope Aperture Alignment Using Kikuchi Shadow Bands
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Solution Overview
Problem
Existing methods for specimen orientation alignment in electron microscopy, particularly using Kikuchi patterns, face challenges in detecting Kikuchi bands when they overlap with diffraction spots, making it difficult to align the incident electron beam with the zone axis of the specimen.
Innovation Solution
An electron microscope system with an aperture that cuts off part of the electron beam, allowing Kikuchi bands to appear in a shadow region, enabling easy detection and alignment by controlling the specimen's inclination based on these bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Kikuchi pattern is used for specimen orientation alignment, then alignment capability is provided, but detection difficulty increases when Kikuchi bands overlap with diffraction spots
Solution Approach 1:
The patent divides the electron beam into two paths using an aperture: one path forms the real image while the other forms the diffraction pattern in the shadow region. This segmentation allows Kikuchi bands to be observed separately from the real image, eliminating overlap and enabling easy detection of crystal orientation without interference from specimen morphology.
2Ease of operation
If conventional alignment methods are used, then alignment can be performed, but specimen damage increases due to prolonged electron beam exposure
Solution Approach 1:
The patent performs alignment using the diffraction pattern in the shadow region before proceeding to real image observation. By completing the orientation alignment step using the separated diffraction information, the need for prolonged electron beam exposure during alignment is reduced, thereby minimizing specimen damage while still achieving accurate crystal orientation alignment.
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
Facilitates easy detection of Kikuchi bands in a shadow region, reducing overlap with real images and minimizing specimen damage, thereby enabling accurate alignment of the specimen orientation.
Implementation Method 1
an aperture that cuts off a part of the electron beam to be irradiated to the specimen
Implementation Method 2
a specimen orientation alignment method using an electron diffraction pattern
Data Source
AI summary
An electron microscope includes an irradiation optical system that irradiates a specimen with an electron beam, a specimen stage that supports the specimen, an image forming optical system that forms an image of electrons transmitted through the specimen, an imaging apparatus that captures an image formed by the image forming optical system, and a control unit that controls inclination of the specimen with respect to an incident direction of the electron beam. The irradiation optical system includes an aperture that cuts off a part of the electron beam to be irradiated to the specimen. The control unit acquires an image including Kikuchi bands that appear in a shadow region of the aperture, detects the Kikuchi bands in the shadow region of the aperture in the image, and controls inclination of the specimen with respect to the incident direction of the electron beam, based on the detected Kikuchi bands.