FPGA-Accelerated Distributed Sensing System for Real-Time Industrial Laser Absorption Spectroscopy Tomography at Kilo-Hertz

Fast and continuous data acquisition (DAQ) with well resolved spectral information is essential for high-speed and high-fidelity measurement of thermophysical parameters of industrial processes using laser absorption spectroscopy tomography (LAST). However, the state-of-the-art DAQ systems suffer a) inability to collect raw spectral data in real time due to the very high data throughput; b) degradation of spectral integrity when excessive on-chip down-sampling is implemented to reduce data throughput. In this work, we designed a star-networked and reconfigurable DAQ system for real-time LAST imaging at kilo-Hz frame rate. The DAQ system is embedded with a new field programmable gate array (FPGA)-accelerated digital lock-in (DLI) technique, whereby a cascaded integrator-comb (CIC) filter is implemented for down-sampling of the raw signal with well-maintained spectral information. Furthermore, a customized data-encapsulation protocol is developed to enable continuity of real-time data communication between the front-end DAQ hubs and back-end processor. Performance of the developed DAQ system is experimentally validated by flame temperature imaging at 1 kHz, providing the necessary temporal
resolution to penetrate turbulent flow and related industrial processes such as reaction propagation.