Metals-based additive manufacturing methods and systems with thermal monitoring and control

A metals-based additive manufacturing machine and method are disclosed. The machine and method include a hybrid temperature monitoring system. The hybrid temperature monitoring system includes a Raman spectrometer, a single-element ultrasound transducer, and a phased-array ultrasound pair. The hybrid temperature monitoring system can generate a real-time three-dimensional temperature map of the melt pool and optionally a portion of the metal powder base and/or a formed portion of a desired artifact. The real-time three-dimensional temperature map can be used for optimizing the metals-based additive manufacturing process in real-time or during subsequent process runs.