title: High-resolution broadband (>100 cm-1) infrared heterodyne spectro-radiometry using an external cavity quantum cascade laser.
abstract: Broadband thermal infrared heterodyne spectro-radiometry using an external cavity quantum cascade laser as a tunable local oscillator has been performed over a frequency range of more than 100 cm(-1) at a central frequency of 1190 cm(-1). Heterodyne spectro-radiometry is demonstrated for two local oscillator tuning modes: broadband tuning for transmission and emission spectroscopy of broadband absorbers (Freon 12), and broadband frequency selection in combination with fine continuous frequency tuning for high-resolution (0.021 cm(-1)) transmission spectroscopy (N(2)O). In each case concentration retrievals are performed and analyzed. The spectroradiometer noise level is demonstrated to be twenty two and eight times the fundamental shot-noise limit in the two scanning modes respectively.
authors.affiliation: Space Science and Technology Department, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, UK. damien.weidmann@stfc.ac.uk
authors.forename: Damien
authors.initials: D
authors.lastname: Weidmann
authors.forename: Gerard
authors.initials: G
authors.lastname: Wysocki
mesh_terms: D004867:Equipment Design; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods; D007259:Infrared Rays; D007834:Lasers; D054023:Lasers, Semiconductor; D055620:Optical Phenomena; D009991:Oscillometry; D010783:Photometry / Q000295:instrumentation / Q000379:methods; D011789:Quantum Theory; D011874:Radiometry / Q000295:instrumentation / Q000379:methods; D013055:Spectrophotometry, Infrared / Q000295:instrumentation / Q000379:methods; D013057:Spectrum Analysis / Q000379:methods