Compact Setup of a Tunable Heterodyne Spectrometer for Infrared Observations of Atmospheric Trace-Gases

• Main Authors: Manuela Sornig, Tobias Stangier, Guido Sonnabend
• Format: Article
• Language: English
• Published: MDPI AG 2013-07-01
• Series: Remote Sensing
• Subjects: heterodyne; infrared; spectroscopy; atmosphere; transmission; ultra-high resolution; ozone; trace gas; wind
• Online Access: http://www.mdpi.com/2072-4292/5/7/3397

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/∆ν ≥ 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/∆ν ≥ 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.