Electron Diffraction Imaging With Adaptive Peak Counting Areas
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Solution Overview
Problem
Direct detection cameras face limitations in dynamic range when capturing electron diffraction patterns, particularly at high dose rates, leading to reduced detective quantum efficiency due to coincidence losses.
Innovation Solution
The method involves using different sets of counting parameter values for pixels belonging to diffraction peaks and those not belonging to them, with smaller coincidence areas for peaks and larger areas for background, and estimating the best dose rate in both counting and integrating modes to generate high-quality diffraction images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electron counting mode is used to capture weak diffraction peaks, then detective quantum efficiency is improved, but dynamic range is limited due to coincidence loss at high dose rates
Solution Approach 1:
The patent applies dynamics by making the coincidence area adjustable rather than fixed. The system dynamically adapts the coincidence area size based on local dose rate conditions: using smaller coincidence areas for high dose rate regions (strong diffraction peaks) and larger coincidence areas for low dose rate regions (weak diffraction peaks), thereby extending dynamic range while maintaining high detective quantum efficiency across varying signal intensities
Solution Approach 2:
The patent implements local quality by applying different coincidence area sizes to different spatial regions within the diffraction pattern. Instead of using a uniform coincidence area for all pixels, the system assigns smaller coincidence areas to pixels corresponding to strong diffraction peaks and larger coincidence areas to pixels corresponding to weak diffraction peaks or background regions, optimizing detection performance locally for each region's specific dose rate characteristics
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 extends the dynamic range of direct detection cameras, reducing coincidence losses and maintaining high detective quantum efficiency even at high dose rates, enabling accurate capture of diffraction peak intensities.
Implementation Method 1
electron diffraction patterns of crystals of these molecules
Implementation Method 2
Direct detection cameras directly detect image-forming electrons without a scintillator
Data Source
AI summary
Method and system for generating a diffraction image comprises acquiring multiple frames from a direct-detection detector responsive to irradiating a sample with an electron beam. Multiple diffraction peaks in the multiple frames are identified. A first dose rate of at least one diffraction peak in the identified diffraction peaks is estimated in the counting mode. If the first dose rate is not greater than a threshold dose rate, a diffraction image including the diffraction peak is generated by counting electron detection events. Values of pixels belonging to the diffraction peak are determined with a first set of counting parameter values corresponding to a first coincidence area. Values of pixels not belonging to any of the multiple diffraction peaks are determined using a second, set of counting parameter values corresponding to a second, different, coincidence area.