X-ray micro-computed tomography with amplitude modulated beams (beam tracking, edge illumination): opportunities, challenges, and outlook

In recent years, x-ray micro-computed tomography (micro-CT) systems with amplitude modulated beams have gained global interest. These systems feature a modulator, that is, an x-ray opaque mask with periodically spaced apertures, in front of the sample, creating an array of spatially separated beamlets. The approach offers x-ray phase contrast imaging (XPCI), which improves the contrast-to-noise ratio and reveals the presence of sub-resolution inhomogeneities by capturing, respectively, refraction and ultra-small angle scattering (dark field signal) alongside x-ray attenuation. Additionally, the modulator can increase spatial resolution, as the narrow beamlets can transfer higher spatial frequencies without requiring geometric magnification. This brief communication reviews the working principle of the approach and comments on a remaining challenge (relatively long scan times).