Compact setup of a tunable heterodyne spectrometer for infrared observations of atmospheric trace-gases

Abstract

We report on the development and characterization of the new compact infrared heterodyne receiver, iChips (Infrared Compact Heterodyne Instrument for Planetary Science). It is specially designed for ground-based observations of the terrestrial atmosphere in the mid-infrared wavelength region. Mid-infrared room temperature quantum cascade lasers are implemented into a heterodyne system for the first time. Their tunability allows the instrument to operate in two different modes. The scanning mode covers a spectral range of few wavenumbers continuously with a resolution of approximately ν/δν >105. This mode allows the determination of the terrestrial atmospheric transmission. The staring mode, applied for observations of single molecular transition features, provides a spectral resolution of ν/δν >107 and a bandwidth of 1.4 GHz. To demonstrate the instrument's capabilities, initial observations in both modes were performed by measuring the terrestrial transmittance at 7.8 μm (~1,285 cm-1) and by probing terrestrial ozone features at 8.6 μm (~1,160 cm-1), respectively. The receivers characteristics and performance are described. © 2013 by the authors; licensee MDPI, Basel, Switzerland.