Rolling Shutter Active Pixel Sensor for X-ray Crystal Centering
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Solution Overview
Problem
Existing methods for centering a crystal sample in single-crystal X-ray diffraction experiments, particularly for small crystals or those in liquids, face challenges with precision and accuracy, especially when using optical or X-ray diffraction-based methods.
Innovation Solution
An X-ray diffraction-based method utilizing an active pixel array sensor operating in rolling shutter mode to detect the presence and absence of diffraction spots as the sample is moved in and out of the X-ray beam, allowing for the determination of the crystal's center by calculating the centroid of the identified edge positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional frame-by-frame detector operation is used, then complete images are captured, but temporal gaps during readout cause loss of diffraction data
Solution Approach 1:
The detector operates in rolling shutter mode where each row continuously integrates X-ray signals without interruption. As one row finishes integration and begins readout, the next row immediately starts integration, ensuring continuous data collection with no temporal gaps between frames.
Solution Approach 2:
The detector is divided into multiple independently operable rows that can be read out sequentially. This segmentation allows each row to maintain continuous integration while the system reads out data from previous rows, eliminating the need to stop data collection during readout operations.
2Quantity of substance
If the entire detector surface is exposed simultaneously, then all diffraction spots are captured in each frame, but the readout time creates gaps in data collection
Solution Approach 1:
Each detector row performs integration (data collection) in advance before its readout operation begins. By the time a row needs to be read out, the integration for that row is already complete, allowing immediate transition to the next row's integration without any gap in overall data collection.
3Measurement precision
If conventional centering methods are used, then the crystal position can be determined, but precision is insufficient for small crystals or those in liquids
Solution Approach 1:
The method replaces mechanical centering approaches with an X-ray diffraction-based detection system using a rolling shutter detector. The continuous diffraction data provides precise positional information about small crystals or those in liquids through automated analysis of diffraction spot positions and intensities.
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 method provides precise and accurate centering of the crystal sample, improving the reliability of single-crystal diffraction analysis by continuously detecting diffraction spots without temporal gaps, enhancing the precision of crystal alignment and data collection.
Implementation Method 1
A single-crystal specimen of the compound is irradiated with monochromatic X-ray radiation from different directions, some of which is diffracted in specific patterns and detected by an active pixel sensor
Implementation Method 2
The pixels of the sensor receive and integrate the X-ray signals
Data Source
AI summary
A method of centering a single crystal sample in the X-ray beam of a diffractometer uses detection of diffraction spots with an active pixel sensor operated in rolling shutter mode. A sample is mounted in the automated goniometer head of the diffractometer and an approximate center of the sample found through which three perpendicular sample axes pass. With a first sample axis perpendicular to a center axis of the X-ray beam, the sample is moved along the first axis from a first position outside of the beam, through the beam and then to a second position outside of the beam. The positions at which first the presence and then the absence of diffraction spots are detected are determined, and the steps repeated for each of the other two perpendicular directions. A precise center may then be found by determining the centroid of the six coordinates thereby obtained.