Shape Measurements in Additive Manufacturing by Structured Light Projection In Situ

In situ and ex situ inspection methods are needed to guarantee the functionality, performance, and structural integrity of additive manufactured (AM) components. Ex situ methods such as infrared thermography, X-ray computed tomography, and ultrasound are used to characterize the functionality and performance of components post-fabrication. In situ methods are used to detect manufacturing defects during the manufacturing processes in real time and to optimize quality control. In this paper, two full-field-of view methods for metrology in situ are described: structured light fringe projection (FP) and optical coherence tomography (OCT). Representative results show that shape measurements with FP can be applied to characterize creep and stress relaxation, while OCT has capabilities to measure surface and subsurface topologies to quantitatively identify subsurface voids and fabrication irregularities in real time. Our investigations indicate that FP and OCT can be miniaturized and integrated into AM environments. Furthermore, in situ measurements can enable the development of AI methods to enhance process monitoring and control real time.