OPTRA proposes the development of a modular, reconfigurable matched spectral filter (RMSF) spectrometer for the monitoring of greenhouse and volcanic gases. The heart of this spectrometer will be an RMSF core, which can be paired with different fore-optics or detector modules to achieve active point or passive standoff detection of the chemicals of interest. The RMSF core is comprised of a dispersive spectrometer that images the sample spectrum from 3 5.5 micron onto a digital micro-mirror device (DMD) such that different columns correspond to different wavebands. By applying masks to this DMD, a matched spectral filter can be applied in hardware. This results in a highly flexible system that can address a wide variety of chemicals by simply updating the DMD masks applied and a wide variety of applications through modular hardware design. Use of the DMD and a single element detector in place of a conventional FPA results in significantly reduced cost and improved performance in terms of image uniformity, pixel operability, and dynamic range. The proposed Phase II effort will produce a prototype RMSF core with one set of fore-optic and detector modules for each of the two detection modalities.