Event-Modulated Electron Microscopy for Low-Dose Signal Capture
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Solution Overview
Problem
Existing electron microscopy techniques face challenges in reducing the electron dose on a sample while maintaining the electron signal, as lowering the dose rate to prevent damage also reduces the signal quality.
Innovation Solution
Employing an electron dose modulator with an arbitrary trigger signal and a digital detector with fast response rate to detect individual electron impact events, allowing precise beam switching, such as turning off the beam once sufficient information is collected, and using a deflector to modulate the electron beam intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the electron dose rate is reduced to prevent sample damage, then sample damage is reduced, but the electron signal quality deteriorates
Solution Approach 1:
The patent applies periodic action by using pulsed electron beam illumination instead of continuous exposure. The beam is delivered in controlled pulses with specific timing, allowing the sample to be exposed only when necessary for data acquisition. This reduces cumulative damage while maintaining signal quality through optimized pulse duration and frequency, directly addressing the contradiction between minimizing damage and preserving signal integrity.
Solution Approach 2:
The patent implements dynamics by making the electron beam intensity and timing adaptive rather than static. The system dynamically adjusts beam parameters based on real-time detection of electron impacts, using feedback mechanisms to modulate the beam. This allows optimal signal collection while minimizing excess exposure, resolving the trade-off between signal quality and sample damage.
2Measurement precision
If the electron beam is continuously exposed to the sample, then the electron signal is maintained, but the sample accumulates damage
Solution Approach 1:
The patent employs feedback by using detectors to monitor electron impacts in real-time and adjusting the beam exposure accordingly. The system detects when sufficient signal data has been collected and automatically reduces or terminates further exposure. This feedback mechanism ensures signal quality is maintained while preventing unnecessary cumulative damage from prolonged exposure.
Solution Approach 2:
The patent applies preliminary action by pre-programming the electron beam exposure based on anticipated signal requirements. The system calculates and prepares optimal exposure parameters before actual data collection, allowing precise control over total dose while ensuring sufficient signal acquisition. This preliminary planning prevents both under-exposure and excessive damage.
3Object-affected harmful factors
If the electron beam is switched off frequently to reduce dose, then sample damage is reduced, but data acquisition efficiency deteriorates
Solution Approach 1:
The patent maintains continuity of useful action by keeping the electron beam active only during periods when signal detection is actually occurring. Through optimized pulse timing and fast detection systems, the beam remains productive throughout its active periods without unnecessary interruptions. This ensures high data acquisition efficiency while minimizing total exposure time, resolving the contradiction between reducing radiation effects and maintaining productivity.
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 reduces sample damage while maintaining high-quality electron signal collection, enabling real-time control and efficient data acquisition with reduced radiation effects.
Implementation Method 1
a focused probe of electrons may be rastered across a specimen. The interaction of the electron beam with the sample material may produce a wide variety of signals
Implementation Method 2
Control over beam switching may allow for blanking of the electron beam once enough information (or even a single event) is detected
Data Source
AI summary
A method for measuring an electron signal or an electron induced signal may be provided. The method may include providing a threshold number of events or a threshold event rate for a pixel on a detector. The method may include collecting from the detector the threshold number of events or determining that the threshold event rate is achieved, wherein a signal at the detector is an electron signal or an electron induced signal from a sample. The method may include modulating an intensity of an electron source directed to the sample in response.