Extended sub-surface imaging in industrial OCT using 'non-diffracting' Bessel beams

Optical coherence tomography (OCT) is an imaging technique which can provide sub-surface evaluation of defects in optically compliant components such as those manufactured by polymeric selective laser sintering. In OCT systems, achieving lateral imaging resolutions of <10 mm means that full-depth imaging requires multiple scans due to the limited depth of focus (DOF). We present a study on the application of 'non-diffracting' Bessel beams to extend system DOF and enable deeper imaging with a single scan. Such capability expands the potential for OCT as a rapid tool for sub-surface assessment, either in-line or in-process, by greatly reducing acquisition times. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of CIRP.