Spatially resolved temperature detection by double scanner and high speed pyrometry for process stabilization of SLS processes
SPIE Proceedings Vol. 11992: Laser 3D Manufacturing IX
Type: Zeitschriftenaufsatz (non-reviewed)
Current strategies for closed loop control of the temperature sensitive selective laser sintering (SLS) process are often based on slow thermal cameras. Another method is single scanner pyrometry. In that case the pyrometer uses the same scanner as the laser. The pyrometer measuring spot and the laser spot are always in the same position. It is not possible to measure temperature outside of the laser spot. In a novel approach, a highly dynamic double scanner system is used to position the measuring beam of a high speed pyrometer. With this approach it is possible to position the laser and measurement spot independently on the powder bed surface (e.g. leading or trailing measurement relative to the laser spot). A very fast pyrometer which outputs measurement data up to 50 kilohertz and FPGA (Field Programmable Gate Array) technology will be used for real time processing of the measured temperature. With this it is possible to process temperature fluctuations on the surface and respond to them very quickly. This technique should be applied to make the SLS process more stable and to get the best results out of the entire build volume. For this purpose, the measured temperature is used to dynamically control the power of the laser.