In-situ Multispectral Melt Pool Monitoring
Off-axial and co-axial multispectral imaging systems that deliver absolute temperature and emissivity maps of the melt pool during PBF-LB/M.
Conventional melt pool monitoring records relative intensity — bright pixels without physical units. This project builds multispectral imaging (MSI) systems that capture several spectral bands simultaneously, enabling pixel-wise separation of temperature and emissivity and therefore absolute temperature maps of the melt pool surface, with less than 2% measurement error after radiometric calibration.
The MSI camera observing the process zone at a spatial resolution of ~1.9 × 1.3 µm per pixel.
Key elements of the project:
- Off-axial MSI: a top-view configuration observing the process zone externally, used for systematic single-track and multi-track studies.
- Co-axial MSI: integration into the laser beam path of the PBF-LB/M machine for a process-synchronous, distortion-free view of the melt pool.
- Radiometric calibration: black-body-based calibration of the SWIR camera and the full optical chain, so measured intensities become traceable temperatures (published in Measurement, 2025).
- Data pipeline: automated processing from raw frames to calibrated temperature and emissivity maps, including melt pool segmentation, geometry extraction, and statistical analysis across hundreds of experimental cases.
- Validation: comparison of MSI-derived melt pool geometry against X-ray imaging.
The resulting temperature fields serve as the measurement backbone for our studies on melt pool physics and laser beam shaping.