Dynamic Electron Microscopy Sample Tilt and Position Control
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Solution Overview
Problem
Current electron microscopy methods for acquiring tilt series are time-consuming and limited in resolution and sample information due to fixed sample positioning during image acquisition, which does not efficiently utilize the high resolution of Transmission Electron Microscopes (TEMs).
Innovation Solution
A method that continuously changes the tilt angle and position of the sample during image acquisition, allowing each image to be taken at a unique tilt angle and position, thereby increasing the imaged sample portion and reducing acquisition time, while also concurrently changing a further tilt angle to reduce the missing wedge effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sample position is kept fixed during tilt series acquisition, then the sample can be stabilized to within 1 nm or less, but the acquisition time becomes very long (1 second or more relaxation time per image)
Solution Approach 1:
The patent applies dynamics by continuously changing the sample position during tilt series acquisition instead of keeping it fixed. The sample holder moves the sample in a controlled manner throughout the tilt range, allowing faster acquisition without compromising the quality of the tilt series data. This dynamic approach eliminates the need for long relaxation times at each tilt position.
2Loss of time
If the sample position is changed continuously during tilt series acquisition, then the acquisition time is reduced, but each image is acquired at a unique position which may complicate alignment
Solution Approach 1:
The patent uses feedback by recording the actual sample position information during continuous movement and using this information during the alignment and reconstruction process. The system tracks and stores position data for each image, which is then used to correctly align images from different positions and tilt angles, simplifying the overall process despite continuous position changes.
3Manufacturing precision
If a traditional tilt series is acquired with fixed sample positioning, then the alignment process is simpler, but the resolution and sample information are limited
Solution Approach 1:
The patent adds another dimension by incorporating continuous sample position changes along with tilt angle changes. This creates a four-dimensional data acquisition approach (x, y, tilt angle, time) instead of the traditional three-dimensional approach, allowing more comprehensive sample information to be captured while maintaining resolution through proper alignment using recorded position data.
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 approach results in faster acquisition times and more detailed sample information, improving the resolution and efficiency of the imaging process without causing unnecessary sample deterioration from radiation damage.
Implementation Method 1
an electron source produces a beam of energetic electrons with a selectable energy of, for example, between 80-300 keV
Implementation Method 2
The sample is sufficiently thin to be transparent to electrons: some electrons are absorbed, but many electrons pass the sample while being scattered or unscattered
Data Source
AI summary
The invention relates to a method of imaging a sample, said sample mounted on a sample holder in an electron microscope, the electron microscope comprising an electron source for generating a beam of energetic electrons along an optical axis and optical elements for focusing and deflecting the beam so as to irradiate the sample with a beam of electrons. The sample holder is capable of positioning and tilting the sample with respect to the electron beam. The method comprises the step of acquiring a tilt series of images by irradiating the sample with the beam of electrons, and concurrently changing a position of the sample during acquisition of the images, so that each image is acquired at an associated unique tilt angle and an associated unique position.