“Extended depth-of-field digital fringe projection for additive manufacturing process monitoring,“ (2026)

W. Keller and S. Zhang, “Extended depth-of-field digital fringe projection for additive manufacturing process monitoring,“ Optics and Lasers in Engineering, 196, 109450 (2026)

Abstract

This paper proposes a novel multi-focus digital fringe projection (DFP) system for use in additive manufacturing (AM) process monitoring. The multi-focus DFP system uses an electronically tunable lens (ETL) to accurately adjust the system's focus. Multiple focus settings are aligned using virtual feature points. Based on the ideal geometry, a label map was created for each layer to identify which pixels correspond to which focus setting. This enables each layer to be 3D reconstructed and stitched together using the minimum number of focus settings. The proposed system achieved sub-millimeter accuracy, with an average aligned RMSE of 0.046 mm. The proposed system was also successfully used for defect detection and correction.