Fig. 1. Schematic layout of experiment. The all-optical inverse Compton scattering source (AOCS) X-ray pulse (yellow) is generated by colliding a laser wakefield acceleration (LWFA) electron beam (blue) with the reflected laser pulse (red) using a plasma mirror. When x-ray photons hit the CsI(Tl) scintillation screen, visible light flashes (orange) are triggered and then captured by an electron-multiplying charge-coupled device.

Fig. 2. LWFA electron-beam characterization: (a) average spectrum of electron beams for 80 consecutive shots measured by an electron spectrometer based on a dipole magnet, where the blurred curve shows the FWHM error and the black dashed line shows the detection threshold; (b) average angular divergence of electron beams for 80 consecutive shots.

Fig. 3. AOCS characterization: (a) accumulated X-ray profile on detector for 50 consecutive shots; (b) X-ray intensity profile attenuated by multi-sector filter set (comprising seven aluminum plates of thickness 0.35 mm–8 mm and seven copper plates of thickness 0.35 mm–9 mm) for 50 consecutive shots; (c) on-axis X-ray spectrum deduced using the data in (b), where the blurred curve shows the error range and the inset shows the calculation error after each iteration. The single-shot source size (d) and the accumulated source size for 80 consecutive shots (e) are measured by the knife-edge technique, and the insets are the images of the sharp edge. (f) Accumulated projection image of a 10-lp/mm line pair for 80 consecutive shots and one of its line-outs, where a ∼20-µm defect within the black dashed square is identified clearly.

Fig. 4. AOCS-based region-of-interest (ROI) micro-focus computed tomography (CT) imaging: (a) illustration of test object, with the ROI highlighted by a red dashed circle; (b) 60-shot accumulated projection image; (c) curve of modulation transfer function of tube edge marked by a black dashed line in the projection image (b); (d) three-dimensional reconstructed image within the ROI; (e) one slice of the tomographic image in (d). The ROIs in (b) and (e) are highlighted by a red dashed rectangle and circle, respectively.

Fig. 5. Numerical simulation of AOCS-based ROI micro-focus CT for a turbine blade: (a) simulation layout—a turbine blade is placed in the x-ray path, with three sets of line pairs embedded in the ROI (within the red dashed circle); (b) photon energy and divergence distribution of AOCS (divergence within 5 mrad is used in the CT scanning); (c) reconstructed ROI of turbine blade; (d) line-outs of reconstructed line pairs with different noise levels (contrasts of the line pairs are labeled).