FIB-SEM Shutter Control for Large-Volume 3D Imaging

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Solution Overview

Problem

Current FIB-SEM systems are limited by slow imaging speed and lack of long-term system stability, restricting the volume of 3D images that can be acquired, which is critical for applications like tracing neuronal processes, due to the destructive nature of the FIB process and requirements for continuous and consistent ablation-imaging cycles.

Innovation Solution

The implementation of a FIB-SEM system with closed-loop control, perpendicular alignment of ion and electron beams, enhanced electron detection, and automatic control mechanisms to prevent beam strikes and maintain stability, allowing for seamless operation and error protection, enabling continuous imaging of large volumes with improved resolution and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If FIB-SEM imaging is performed with traditional sequential ablation-imaging cycles, then high z-resolution can be achieved, but imaging speed is slow and the maximum acquisition volume is limited

Engineering Contradiction:
Improvez-resolutionVSAvoidimaging speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system performs preliminary alignment and calibration of the ion beam and electron beam paths before actual imaging begins. Mechanical shutters are pre-positioned and safety interlocks are pre-configured, allowing the imaging process to start immediately without delays during the actual ablation-imaging cycles

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements continuous automated ablation-imaging cycles without manual intervention between steps. The ion beam and electron beam operations are continuously coordinated through automated control systems, eliminating idle time and maintaining uninterrupted imaging flow to maximize productivity while preserving z-resolution

Inventive Principle:
Principle #20Continuity of useful action

2Volume of moving object

If FIB-SEM imaging is performed for extended periods to increase acquisition volume, then larger volumes can be imaged, but system stability deteriorates and errors increase

Engineering Contradiction:
Improveacquisition volumeVSAvoidsystem stability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The system continuously monitors beam positioning, ablation depth, and imaging quality parameters throughout extended operation. Automated feedback control adjusts beam parameters and shutter timing in real-time to compensate for drift and maintain consistent performance over long acquisition periods, enabling large volume imaging while preserving system stability

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system incorporates mechanical shutters and safety interlocks that are pre-positioned to automatically protect against beam strikes and system errors before they can cause damage. These protective mechanisms are ready to activate immediately upon detecting abnormal conditions, cushioning against potential failures during extended operation

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Manufacturing precision

If the FIB process operates with high precision requirements for continuous ablation, then imaging quality is maintained, but any interruption causes damage and requires perfect continuity

Engineering Contradiction:
Improveablation consistencyVSAvoidcontrol mechanism complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system merges the ion beam control, electron beam control, mechanical shutter operation, and safety monitoring into a single integrated automated control system. This unified approach manages the complexity of maintaining perfect ablation continuity while coordinating all components to work together seamlessly, ensuring imaging quality without requiring separate complex control mechanisms for each function

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If mechanical shutters are used to protect against beam strikes, then system reliability is improved, but response time may be delayed

Engineering Contradiction:
Improveerror protectionVSAvoidshutter response time
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The mechanical shutters are pre-positioned in the beam path and pre-loaded in ready-to-activate configurations before imaging begins. Safety interlocks and detection systems are pre-configured to immediately trigger shutter closure upon detecting abnormal conditions, eliminating activation delays and ensuring fastest possible response time for error protection

Inventive Principle:
Principle #10Preliminary action

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 enables reliable and efficient imaging of large volumes, such as entire Drosophila brains, with high z-resolution, overcoming previous limitations and expanding the total imaging volume possible, while maintaining high virtual reliability and minimizing damage from interruptions.

Implementation Method 1

a means for removing successive surface layers of the sample

Methodology Applied
Scientific EffectAblation: Ablation

Implementation Method 2

a detector configured for detecting a signal of electrons emitted from the sample in response to the irradiation by the primary electron beam

Methodology Applied
Scientific EffectElectron emission and detection: Photoelectric Effect

Data Source

PatentEP3574518B1Enhanced FIB-SEM systems for large-volume 3D imaging
Publication Date: 2021.09.01 HOWARD HUGHES MEDICAL INST
  • EP3574518B1 patent drawingFigure 1
  • EP3574518B1 patent drawingFigure 2
  • EP3574518B1 patent drawingFigure 3

AI summary

A microscopy system for imaging a sample can include a scanning electron microscope system configured for imaging a surface layer of the sample and a focused ion beam system configured for generating an ion beam for milling the surface layer away from a sample after it has been imaged. A movable mechanical shutter can be configured to be moved automatically into a position between the sample and the scanning electron microscope system, so that when the electron beam is not imaging the sample the movable mechanical shutter is positioned between the sample and the scanning electron microscope system.