A new type of neutron computed laminography scanning method and centre of rotation calibration algorithm for plate-like components

Neutron computed laminography (CL) is a special neutron tomographic imaging technology for plate-like components. The neutron beam is considered to be parallel, and the projection image has geometric unsharpness artefact, which reduces the spatial resolution of reconstructed image. It is an effective measure to improve the spatial resolution by making sample close to the imaging plane under the CL scanning mode. Therefore, a new type of neutron CL (NTNCL) scanning mode was designed: the imaging plane was adjusted to be parallel to the sample carrying disc, so that the sample was close to the imaging plane during CL scanning. For the NTNCL scanning mode, the FBP (filtered back-projection) reconstruction algorithm and the accurate calibration algorithm of centre of rotation (COR) were designed. Based on the China Advanced Research Reactor (CARR), a NTNCL tomography experiment of a plate-like copper foam sample with glue inside was carried out. Computer simulation results showed that the NTNCL scanning mode, the proposed reconstruction algorithm and the COR calibration algorithm could effectively improve the reconstructed image resolution of plate-like components. Moreover, the experimental results further verified the sensitivity and effectiveness of neutron CL imaging for detection of viscose material.