The selective laser sintering (SLS) process is very temperature sensitive, so slight temperature changes can lead do inhomogeneous prints with varying mechanical properties. The laser power is kept at a fixed value while printing because most SLS printers assume a constant temperature in the building volume on the powder surface. The assumption of an even temperature distribution is incorrect in a lot of cases. In this chapter a modular system for the monitoring and controlling of laser based double scanner systems is presented. Also very fast signals (e.g. temperature) can be processed and used for a process control (e.g. controlled laser power). Current strategies for temperature control of the sensitive SLS process are often based on slow thermal cameras or single scanner pyrometry. In a novel approach, a highly dynamic double scanner system is used to position the measuring beam of a high speed pyrometer independently from the laser spot. FPGA technology (Field Programmable Gate Array) is used to manipulate scanner trajectories in real time and to process the pyrometer data. With this approach, new measurement and control strategies are possible.