Retractable SEM Projector for On-Axis Diffraction Imaging
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Solution Overview
Problem
Existing scanning electron microscopes (SEM) are limited by the resolution of on-axis diffraction techniques due to the lack of space for incorporating projectors that enhance resolution, as traditional TEM projectors are too large and heavy for SEM systems.
Innovation Solution
Incorporating a retractable and cooled projector that can be positioned along the optical axis of the SEM to enhance diffraction imaging resolution for thin samples, and retracting it to accommodate thicker samples using backscattered or secondary electron detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional TEM projector is incorporated into the SEM to enhance diffraction imaging resolution, then the measurement precision of diffraction patterns is improved, but the device complexity and size increase significantly
Solution Approach 1:
The patent applies the copying principle by creating a simplified version of the TEM projector specifically adapted for SEM integration. Instead of using the full-scale TEM projector, a compact projector design is implemented that replicates the essential diffraction pattern projection function while being significantly reduced in size and weight to fit within the SEM column architecture.
Solution Approach 2:
The patent applies local quality by positioning the projector at a specific location within the SEM column where it can optimally receive the electron beam from the sample and project the diffraction pattern onto the detector. The projector is strategically placed in the projection region between the sample and detector, allowing it to perform its function locally without interfering with other SEM components.
2Measurement precision
If the projector is positioned along the optical axis to enable on-axis diffraction imaging, then the measurement precision is improved, but the adaptability to different sample types is reduced
Solution Approach 1:
The patent applies the dynamics principle by making the projector movable rather than fixed. The projector can be dynamically repositioned along the optical axis and adjusted in its operational state, allowing the system to switch between on-axis diffraction imaging mode (for thin samples) and conventional SEM imaging mode (for thicker samples), thereby achieving adaptability to different sample types while maintaining high resolution capability when needed.
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
Enables higher resolution on-axis transmission diffraction imaging for thin samples while allowing imaging of thicker samples using conventional SEM modes, without increasing the size or weight of the SEM.
Implementation Method 1
the primary electron beam produced by the electron source is emitted from the electron source along the optical axis of the SEM
Implementation Method 2
detecting on-axis transmission diffraction patterns with SEM
Data Source
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AI summary
In accordance with the present invention, there is provided a scanning electron microscope comprising: an electron source; a sample holder for holding a sample to be analysed; a projector; and a first detector. Each of the electron source and the sample holder are arranged upon an optical axis of the scanning electron microscope. The projector is moveable between a first, operational position in which the projector is located along the optical axis downstream of the sample holder and between the sample holder and the first detector, and a second, retracted position in which the projector is located away from the optical axis. There is also provided a method of imaging a sample with the scanning electron microscope.