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Medium Wavelength Infrared (MWIR) Imaging for High Speed Control of Laser Metal Deposition (LMD)
V. Panadeiro-Castro, J. Rodriguez-Araújo, A. García-Díaz and G. Vergara

Laser metal deposition (LMD) is a material processing technique widely used in industry for part reconstruction, coating or rapid prototyping. The inherent non-repetitiveness of the technique makes mandatory a closed-loop control of the process when homogeneous results are required, since it is affected by the material, size, and geometry of the part. Based on the use of uncooled PbSe image sensors working in the medium wavelength infrared (MWIR) range (1 to 5 μm), we present a novel high-speed closed-loop control for LMD. Controlling laser power at high speed (1 kHz) based on measurements from the melt pool thermal image down to 200ºC enhances current solutions based on complementary metal-oxide-semiconductor (CMOS) images, blind to temperatures under 600ºC. To demonstrate the performance of the controller, claddings on different surfaces and geometries were carried out. Experimental results demonstrate the advantage of this approach in terms of sensitivity to process related magnitudes an overall control stability.

Keywords: Fibre laser, laser metal deposition (LMD), laser cladding, medium wavelength infrared (MWIR), closed-loop control, PbSe focal plane array (FPA), real-time control

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