Lensless sideways imaging with digital holography for in-line process monitoring in additive manufacturing

In additive manufacturing, quality assurance typically involves off-line control measurements, which are costly and time-consuming. Therefore, in-line monitoring is crucial for improving efficiency and minimizing errors. We propose a new concept using lensless digital holography for off-axis full-field measurements. It enables aberration free sideways imaging with high observation angles, allowing for new freedoms concerning the camera positioning for in-line process monitoring. The technique was tested in simulations and experiments with off-axis angles up to 45 degrees, offering an effective solution for real-time quality control in additive manufacturing.