The TFS is an all-optical analytical platform using a Tunable Filter Spectrometer. The TFS offers a multi-component gas analysis at unparalleled speed. The Tunable Filter Spectrometer measures at unparalleled speed (<5 sec). The TFS requires no carrier gas and accurately measures the BTU Heating Index and Wobbe Index. It uses infrared absorption to measure methane, ethane, propane, butanes pentanes, carbon dioxide and % level H2S.