Retractable, rotatable gratings allow different measurement techniques within a single apparatus

For proper evaluation of carbon fiber reinforced plastic laminates (CFRPs) and other materials with unknown inner structures, both micro computed tomography (micro-CT) and Talbot-Lau interferometry imaging are desirable. Morimoto et al. developed a nondestructive X-ray imaging system equipped with retractable and rotatable grating structures, which allows for the implementation of different imaging measurements within a single apparatus.

The system has a set of three gratings, necessary for conventional Talbot-Lau interferometry. Depending on how the gratings are rotated or retracted from the beam axis, several different projection and tomography imaging modes can be realized. For example, removing the gratings allows for conventional absorption imaging and micro-CT. Directional X-ray dark-field imaging can be performed by rotating the grating at various angles in relation to the beam axis.

“The grating rotating structure enables flexible selection of the measurements. Different types of measurements can be employed in this apparatus,” said author Naoki Morimoto. “This is attributed to the anisotropic sensitivity of Talbot-Lau interferometry.”

In testing the method, the authors were able to compare signals obtained from different techniques by retracting the gratings and altering their orientations. This allowed them to observe cracks, fine structures and other features traditional imaging techniques cannot resolve independently.

The method is not limited to studying the mechanical properties of CFRPs. The authors investigated polymers, biological tissues and ceramic samples using this apparatus. They note the significant contrast produced by Talbot-Lau interferometry makes it a useful technique for imaging materials with weak absorption characteristics.

Source: “Talbot-Lau interferometry-based x-ray imaging system with retractable and rotatable gratings for nondestructive testing,” by N. Morimoto, K. Kimura, T. Shirai, T. Doki, S. Sano, A. Horiba, and K. Kitamura, Review of Scientific Instruments (2020). The article can be accessed at https://doi.org/10.1063/1.5131306 .