X-ray directional dark-field imaging using Unified Modulated Pattern Analysis

Area of Science:

• Materials Science
• Physics
• Imaging Technology

Background:

• Conventional X-ray imaging lacks the resolution to reveal small-scale structural properties.
• Anisotropic structures possess directional properties that are difficult to detect with standard methods.
• X-ray directional dark-field imaging is an emerging technique offering enhanced contrast for microstructural analysis.

Purpose of the Study:

• To develop and present an algorithm for extracting directional dark-field signals from X-ray speckle-based imaging data.
• To demonstrate the capability of the technique in detecting and quantifying the orientation of anisotropic structures.
• To analyze the accuracy and resolution trade-offs of the proposed method.

Main Methods:

• Utilizing X-ray speckle-based imaging with a simple diffuser (sandpaper) in a full-field microscope setup.
• Developing an algorithm to extract directional dark-field signals, mean scattering width, directionality, and orientation from speckle images.
• Acquiring and analyzing data from a carbon fibre reinforced polymer (CFRP) sample.

Main Results:

• Successfully extracted directional dark-field signals from X-ray speckle data.
• Demonstrated accurate detection and quantification of fibre orientation in CFRP samples, achieving within one degree of accuracy.
• Quantified the relationship between the number of measurements and the achieved accuracy.
• Showcased the ability to tune reconstruction parameters for accuracy versus spatial resolution.

Conclusions:

• The presented algorithm effectively extracts directional dark-field information from X-ray speckle data.
• The technique provides accurate orientation information for anisotropic materials, with potential applications in materials science and engineering.
• The method's accuracy is dependent on the number of measurements and can be optimized by adjusting reconstruction parameters.