Complementary coded apertures for 4-dimensional x-ray coherent scatter imaging

Abstract

X-ray scattering has played a key role in non-destructive materials characterization due to the material-specific coherent scattering signatures. In the current energy dispersive coherent scatter imaging systems, including selected volume tomography and coherent scatter computed tomography, each object voxel is measured at a single scatter angle, which suffers from slow acquisition time. The employment of coded apertures in x-ray scatter imaging systems improves the photon collection efficiency, making it promising for real time volumetric imaging and material identification. In this paper, we propose a volumetric x-ray scatter imaging system using a pair of complementary coded apertures: a coded aperture on the detector side introduces multiplexed measurement on an energy-sensitive detector array; a complementary source-side coded aperture selectively illuminates the object to decouple the ambiguity due to the increased parallelization for 4D imaging. The system yields the 1D coherent scattering form factor at each voxel in 3D. We demonstrate tomographic imaging and material identification with the system and achieve a spatial resolution ~1 cm and a normalized momentum transfer resolution, Δq/q, of 0.2.

Three‐dimensional reciprocal space x‐ray coherent scattering tomography of two‐dimensional object

“…The allowable range of detector movement along z direction confines the gradient of these curves, thus restricting the projection angles in the domain, which is analogous to the limited‐angle CT problem . The location of the voxel and its scattering angle are highly coupled in the domain, which cannot be fully decoupled with limited projection angle. The green intersection area in Fig.…”

X-ray diffraction tomography with limited projection information

“…Since the diffracted X-rays deviate from the incident beam, depth of the scatter along the beam can be resolved with specifically-designed encoding patterns on either the illumination side 11 – 13 or detector side 14 , 15 . However, due to the small scattering angle, the achievable depth resolution of these methods is on the order of 10 mm.…”

Compressive video sensing with side information

“…Recently, we also investigated the scenario where the two measurements are measuring the scene from different perspectives, which could provide the range information [37][38][39][40] and polarization [41] of the scene and has potential in high-speed stereo imaging applications [42]. A similar idea can also be used in other bandwidth imaging systems, e.g., x rays [43][44][45][46].…”