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SUMMARY:Quantum cascade laser heterodyne radiometry for atmospheric soundi
 ng: application to atmospheric ozone monitoring - Dr Damien Weidmann\, STF
 C Rutherford Appleton Laboratory
DTSTART:20090324T110000Z
DTEND:20090324T120000Z
UID:TALK17059@talks.cam.ac.uk
CONTACT:Dr Francis Pope
DESCRIPTION:Recent outcomes from photonics research have yielded the adven
 t of continuously\ntuneable semiconductor laser sources offering high opti
 cal power output and\nexcellent spectral purity.  Quantum cascade lasers (
 QCLs) can be tailored to\nemit laser radiation from 4 m to 150 m in 
 a robust and extremely compact\npackage.  They provide an excellent opport
 unity to develop new highly sensitive\nand compact instrumentation for atm
 ospheric research both for in situ and\nremote monitoring.\n\nA novel pass
 ive remote sensing instrument based on a mid-infrared QCL operating\nat 9.
 7 m will be presented: a ground-based prototype laser heterodyne\nradio
 meter (LHR) has been developed within the Space Science and Technology\nde
 partment of the Rutherford Appleton Laboratory. Principles\, advantages\, 
 and key elements of the instrument will be discussed. Measurements on carb
 onyl sulphide have been used to assess the performance of the LHR in the l
 aboratory\, and a detection limit equivalent to three times the ultimate s
 hot noise limit has been observed.  Results from solar occultation atmosph
 eric transmission measurements targeting ozone will be presented\, includi
 ng ozone profiles retrieved using the optimal estimation method. Measureme
 nt information content and retrieval errors will also be discussed.  This 
 first atmospheric measurement campaign has shown that ozone mixing ratios 
 up to an altitude of 35 km may be retrieved with an average vertical resol
 ution of 4 km.  This initial deployment of the ground-based prototype LHR 
 has been highly successful and has demonstrated the potential of laser het
 erodyne radiometry to deliver excellent sensitivity at high spatial and sp
 ectral resolution in an unprecedented compact package.\n\nTo conclude an o
 utline of methods to improve instrument performance and the current develo
 pments being undertaken will be given.\n\n
LOCATION:BAS room 330b
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