Process and Controls OverviewDue to

Process and Controls Overview
Due to the aforementioned experimental results, it has been determined that a robust
temperature feedback control system will be required in order to generate the proper
microstructure in the repair process. The primary components utilized in the experimental SLE
feedback controls consist of a Hobart 2.2 kW 1064 nm Nd:YAG laser, a Cambridge
Technologies galvanometer laser scanner, a Pyrofiber emissivity correcting pyrometer, an array
of Omega K-type thermocouples, and a Coherent high power digital power meter. Additionally,
a Sony video microscope with a bandpass optical filter is also included for post-processing
analysis purposes. Figure 8 shows an overview of the SLE process control layout. The outputs of
the system are XML format based laser positioning vectors and an analog laser power signal.
The laser power, melt pool temperature, and the temperature of the substrate bottom are utilized
as feedback signals.