Article Article
Thermal Calibration of Ratiometric, On-Axis Melt Pool Monitoring Photodetector System Using Tungsten Strip Lamp

In situ melt pool monitoring is a set of technologies widely deployed on industrial, metals-based laser powder bed fusion (LPBF) additive manufacturing (AM) systems. This study investigates the use of a calibrated tungsten ribbon lamp as a reference standard to calibrate a photodetector based, on-axis melt pool monitoring system. Calibration demonstrates two functions: (a) enable a reference for measuring and ensuring system repeatability, and (b) enable reference to physical temperature values based on the measured photodetector signals. The second function is explored in this paper. A regression-based model is derived based on bichromatic Planck thermometry theory. The calibrated tungsten lamp is then placed within a LPBF system, and resulting photodetector signals are measured at different lamp temperature set points to calibrate the model. Finally, several additional characterization tests and their results are presented verifying the temporal response of the lamp, measurement noise as a function of sampling time, and spectroscopic measurements of the LPBF optics and their potential effect on temperature calibration. A framework is also developed to normalize temperature readings across the build plate to remove location-dependent optical artifacts.



Bronstein, M.M., J. Bruna, T. Cohen, and P. Velicˇkovic′, 2021, “Geometric Deep Learning: Grids, Groups, Graphs, Geodesics, and Gauges,” ArXiv:2104.13478 [Cs, Stat],

Chauveau, D., 2018, “Review of NDT and Process Monitoring Techniques Usable to Produce High-Quality Parts by Welding or Additive Manufacturing,” Welding in the World, Vol. 62, pp. 1097–1118,

Coates, P.B., 1981, “Multi-Wavelength Pyrometry,” Metrologia, Vol. 17, No. 3, p. 103,

Deisenroth, D.C., S. Mekhontsev, B. Lane, L. Hanssen, I. Zhirnov, V. Khromchenko, S. Grantham, D. Cardenas-Garcia, and A. Donmez, 2021, “Measurement Uncertainty of Surface Temperature Distributions for Laser Powder Bed Fusion Processes,” Journal of Research of the National Institute of Standards and Technology, Vol. 126,

Dunbar, A.J., and A.R. Nassar, 2018, “Assessment of Optical Emission Analysis for In-Process Monitoring of Powder Bed Fusion Additive Manufacturing,” Virtual and Physical Prototyping, Vol. 13, No. 1, pp. 14–19,

Everton, S.K., M. Hirsch, P. Stravroulakis, R.K. Leach, and A.T. Clare, 2016, “Review of In Situ Process Monitoring and In situ Metrology for Metal Additive Manufacturing,” Materials & Design, Vol. 95, pp. 431–445,

Gibson, C.E., B.K. Tsai, and A.C. Parr, 1998, “Radiance Temperature Calibrations,” NIST Special Publication 250-43, National Institute of Standards and Technology, Gaithersburg, MD,

Grasso, M., and B.M. Colosimo, 2017, “Process Defects and In Situ Monitoring Methods in Metal Powder Bed Fusion: A Review,” Measurement Science and Technology, Vol. 28,

Hooper, P.A., 2018, “Melt Pool Temperature and Cooling Rates in Laser Powder Bed Fusion,” Additive Manufacturing, Vol. 22, pp. 548–559,

Khairallah, S.A., A.T. Anderson, A. Rubenchik, and W.E. King, 2016, “Laser Powder-Bed Fusion Additive Manufacturing: Physics of Complex Melt Flow and Formation Mechanisms of Pores, Spatter, and Denudation Zones,” Acta Materialia, Vol. 108, pp. 36–45,

Lane, B., L. Jacquemetton, M. Piltch, and D. Beckett, 2020, “Thermal Calibration of Commercial Melt Pool Monitoring Sensors on a Laser Powder Bed Fusion System,” NIST Advanced Manufacturing Series 100-35, National Institute of Standards and Technology, Gaithersburg, MD,

McCann, R., M.A. Obeidi, C. Hughes, É. McCarthy, D.S. Egan, R.K. Vijayaraghavan, A.M. Joshi, V.A. Garzon, D.P. Dowling, P.J. McNally, and D. Brabazon, 2021, “In Situ Sensing, Process Monitoring and Machine Control in Laser Powder Bed Fusion: A Review,” Additive Manufacturing, Vol. 45,

Meng, L., B. McWilliams, W. Jarosinski, H.-Y. Park, Y.-G. Jung, J. Lee, and J. Zhang, 2020, “Machine Learning in Additive Manufacturing: A Review,” JOM, Vol. 72, pp. 2363–2377,

Saunders, P., 2007, Radiation Thermometry: Fundamentals and Applications in the Petrochemical Industry, SPIE Press 

Snow, Z., A.R. Nassar, and E.W. Reutzel, 2020, “Review of the Formation and Impact of Flaws in Powder Bed Fusion Additive Manufacturing,” Additive Manufacturing, Vol. 36,

Snow, Z., B. Diehl, E.W. Reutzel, and A. Nassar, 2021, “Toward In Situ Flaw Detection in Laser Powder Bed Fusion Additive Manufacturing through Layerwise Imagery and Machine Learning,” Journal of Manufacturing Systems, Vol. 59, pp. 12–26,

Spears, T.G., and S.A. Gold, 2016, “In-Process Sensing in Selective Laser Melting (SLM) Additive Manufacturing,” Integrating Materials and Manufacturing Innovation, Vol. 5, pp. 16–40,


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