Helical Beam Trajectory via Image Shift and Alpha Tilt
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Solution Overview
Problem
Electron-based tomography faces challenges such as poor image-to-image alignment, missing wedges, and inadequate imaging quality due to sample drifting and contamination during image acquisition, particularly at cryogenic temperatures, leading to excessive image sequence durations and computational processing times.
Innovation Solution
The method involves using beam deflection instead of mechanical translation to reduce sample movement, allowing for helical imaging trajectories and minimizing drift-induced settling times, thereby reducing the duration of helical imaging sequences and improving image quality by coordinating beam deflection with sample rotation to achieve efficient 3D reconstructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical translation is used to move the sample during imaging, then sample positioning is achieved, but sample drifting and contamination occur during prolonged acquisition
Solution Approach 1:
The patent replaces mechanical translation of the sample with beam deflection to move the imaging beam across different sample locations. The beam is deflected along a helical trajectory while the sample remains stationary or rotates slowly, eliminating mechanical drift and contamination issues associated with prolonged sample manipulation.
Solution Approach 2:
Instead of moving the sample to achieve different imaging positions, the patent inverts the approach by keeping the sample stationary (or slowly rotating) and moving the imaging beam through deflection. This reversal eliminates the harmful effects of mechanical sample manipulation while achieving the same imaging goals.
2Adaptability or versatility
If the sample is rotated to multiple positions for tomography, then 3D reconstruction is enabled, but image acquisition time increases leading to sample contamination
Solution Approach 1:
The patent implements continuous helical scanning where the beam deflects continuously along a helical trajectory while the sample rotates continuously. This continuous action eliminates the need to stop and settle at discrete angular positions, dramatically reducing total acquisition time while maintaining complete 3D sampling for reconstruction.
Solution Approach 2:
The patent pre-coordinates the beam deflection trajectory with the sample rotation speed and phase. The helical deflection pattern is designed in advance to match the rotational motion, ensuring optimal sampling density and eliminating the need for time-consuming settling periods between positions.
3Productivity
If the imaging beam is deflected to multiple sample locations, then helical imaging trajectory is achieved, but beam aberrations are introduced
Solution Approach 1:
The patent introduces a descanning lens as an intermediary optical element between the beam deflector and the sample. This descanning lens compensates for the aberrations introduced by the beam deflector, correcting image quality while preserving the high-speed helical scanning capability.
Solution Approach 2:
The patent adjusts optical parameters of the imaging system, specifically introducing descanning optics with appropriate focal lengths and positioning. By changing these optical parameters, the system corrects beam aberrations while maintaining the high-speed helical trajectory 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 approach significantly reduces the time required for image acquisition and enhances image quality by minimizing mechanical translations and drift-related issues, while maintaining or improving the resolution and detail of 3D reconstructions in electron-based tomography.
Implementation Method 1
directing the imaging beam to a second sample location by deflecting the imaging beam in relation to an optical axis of the imaging beam
Implementation Method 2
rotating the sample using the movement stage about the rotation axis to a second rotational position
Data Source
AI summary
Methods include holding a sample with a movement stage configured to rotate the sample about a rotation axis, directing an imaging beam to a first sample location with the sample at a first rotational position about the rotation axis and detecting a first transmitted imaging beam image, rotating the sample using the movement stage about the rotation axis to a second rotational position, and directing the imaging beam to a second sample location by deflecting the imaging beam in relation to an optical axis of the imaging beam and detecting a second transmitted imaging beam image, wherein the second sample location is spaced apart from the first sample location at least at least in relation to the optical axis. Related systems and apparatus are also disclosed.