Optical Misalignment Correction in Differential Phase Contrast Imaging
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Solution Overview
Problem
Differential phase contrast imaging systems face misalignment issues, particularly in larger structures, leading to suboptimal results due to deviations in distance and inclination of grating components, which existing technologies have not effectively addressed.
Innovation Solution
An X-ray imaging system with a differential phase contrast setup incorporating a source grating, phase grating, and analyser grating, equipped with an optical measurement system using sensors like 4-quadrant photodiodes and interferometers to determine misalignment, and actuators for precise alignment correction, ensuring accurate positioning and phase analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If grating arrangement is adjusted to achieve nanometer-level precision, then imaging quality improves, but system complexity and alignment difficulty increase
Solution Approach 1:
The patent replaces mechanical alignment adjustment with optical measurement and electronic correction. Optical sensors (photodiodes, interferometers) measure grating positions, and electronic processing corrects misalignment effects through image processing algorithms, eliminating the need for complex mechanical precision adjustment mechanisms.
Solution Approach 2:
The patent implements a feedback system where optical sensors continuously monitor grating positions and provide measurement data to a processing unit. The system calculates misalignment corrections based on sensor feedback and applies these corrections through image processing, creating a closed-loop control system that maintains alignment precision.
2Measurement precision
If optical measurement system is added to determine misalignment, then alignment accuracy improves, but device complexity increases
Solution Approach 1:
The patent introduces optical sensors as intermediary devices that indirectly measure grating positions by detecting light patterns rather than directly measuring mechanical positions. This intermediary approach enables high-precision measurement without requiring direct mechanical contact or complex measurement mechanisms.
Solution Approach 2:
The patent substitutes mechanical measurement devices with optical measurement systems. Instead of using mechanical gauges or direct position sensors, the system uses optical fields (light patterns, interferometry) to measure grating positions, achieving higher precision with non-contact measurement.
3Stability of the object's composition
If rigid X-ray source unit and detection unit are used, then alignment stability improves, but adaptability to misalignment decreases
Solution Approach 1:
The patent combines rigid mechanical structures with optical feedback measurement and electronic correction. The rigid units provide stable mechanical baseline, while the optical sensors detect any drift or misalignment, and electronic processing compensates for these changes, achieving both stability and adaptability.
Solution Approach 2:
The patent changes the approach from mechanically adjusting physical parameters (grating positions) to electronically adjusting processing parameters (image correction algorithms). The rigid structures maintain physical stability while software parameter changes provide adaptability to misalignment conditions.
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
The system effectively corrects misalignment with high accuracy, improving the quality of imaging results by ensuring precise alignment of grating components, thereby enhancing the sensitivity and resolution of differential phase contrast imaging.
Implementation Method 1
the at least three sensors are provided as at least three 4-quadrant photodiodes. An optical source device fixedly attached to the X-ray source unit is configured to generate a light beam to each of the 4-quadrant photodiodes
Implementation Method 2
A further approach is to provide an interferometer for the phase measurement, e.g. a so-called Michelson laser interferometer
Data Source
AI summary
The present invention relates to handling misalignment in differential phase contrast imaging. In order to provide an improved handling of misalignment in X-ray imaging systems for differential phase contrast imaging, an X-ray imaging system (10) for differential phase contrast imaging is provided that comprises a differential phase contrast setup (12) with an X-ray source (14), an X-ray detector (16), and a grating arrangement comprising a source grating (18), a phase grating (20) and an analyzer grating (22). The source grating is arranged between the X-ray source and the phase grating, and the analyzer grating is arranged between the phase grating and the detector. Further, the system comprises a processing unit (24), and a measurement system (26) for determining a misalignment of at least one of the gratings. The X-ray source and the source grating are provided as a rigid X-ray source unit (28). The phase grating, the analyzer grating and the detector are provided as a rigid X-ray detection unit (30). The measurement system is an optical measurement system configured to determine a misalignment between the differential phase contrast setup consisting of the X-ray source unit and the X-ray detection unit. Further, the processing unit is configured to provide a correction signal (34) based on the determined misalignment.