22 May 2015 Breadboard sized photo-acoustic spectroscopy system using an FPGA based lock-in amplifier
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Over the past several years we have developed a photo-acoustic spectroscopic (PAS) technique for trace gas detection that is capable of parts per trillion (ppt) detection limits. The desire to reduce the size of the system has led to several efforts that have reduced the size of the various components of the system. We have reduced the dimensions of the resonant cell to micrometer scale (MEMS). We have worked with Daylight Solutions to reduce the size of the tunable quantum cascade laser (QCL) used in the system. In this paper we demonstrate the reduction in size of the entire system to a 12” x 12” footprint. We do this by implementing the lock-in amplifier on a field programmable gate array (FPGA) demonstration board that is also capable of acting as the system controller and data output device. We briefly describe the digital lock-in amplifier and sketch our implementation on the FPGA. We go on to compare the spectroscopic data we collected using this system with data we collected using a large rack mounted Stanford Research Systems SR830 lock-in amplifier and a PC.
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John F. Schill, John F. Schill, Paul M. Pellegrino, Paul M. Pellegrino, Ellen L. Holthoff, Ellen L. Holthoff, Mark M. Giza, Mark M. Giza, "Breadboard sized photo-acoustic spectroscopy system using an FPGA based lock-in amplifier", Proc. SPIE 9455, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XVI, 94550Z (22 May 2015); doi: 10.1117/12.2178160; https://doi.org/10.1117/12.2178160

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