Large depth of field structured light micro-vision system for 3D measurement based on dual electrically tunable lenses

The limited depth of field (DOF) in high-magnification systems poses a significant challenge to the application of micro-structured light 3D measurement technology. To address this issue, we designed a micro-vision system in which both the projection and imaging optical paths incorporate electrically tunable lenses (ETLs). A corresponding large-DOF structured light experimental scheme and computational framework were proposed. By leveraging the rapid focus-adjustment capability of the ETL, the scheme utilizes focal sweep projection with binary fringe and focus stacking imaging to independently extend the DOF of the projection and imaging paths. Additionally, a dedicated hardware timing control sequence was introduced for synchronization between the projection and imaging optical paths. The computational framework further details the procedures of processing acquired fringe images to reconstruct large-DOF scenes. Experimental results demonstrate that, within a field of view (FOV) of 8.7 mm × 4.8 mm, the DOF was effectively extended to 8.0 mm.