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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:TALK17053@talks.cam.ac.uk
CONTACT:Dr Thomas Bracegirdle
DESCRIPTION:Recent outcomes from photonics research have yielded the adven
 t of continuously tuneable semiconductor laser sources offering high optic
 al power output and excellent spectral purity.  Quantum cascade lasers (QC
 Ls) can be tailored to emit laser radiation from 4 m to 150 m in a r
 obust and extremely compact package.  They provide an excellent opportunit
 y to develop new highly sensitive and compact instrumentation for atmosphe
 ric research both for in situ and remote monitoring.\n\nA novel passive re
 mote sensing instrument based on a mid-infrared QCL operating at 9.7 m 
 will be presented: a ground-based prototype laser heterodyne radiometer (L
 HR) has been developed within the Space Science and Technology department 
 of the Rutherford Appleton Laboratory.  Principles\, advantages\, and key 
 elements of the instrument will be discussed.  Measurements on carbonyl su
 lphide have been used to assess the performance of the LHR in the laborato
 ry\, and a detection limit equivalent to three times the ultimate shot noi
 se limit has been observed.  Results from solar occultation atmospheric tr
 ansmission measurements targeting ozone will be presented\, including ozon
 e profiles retrieved using the optimal estimation method.  Measurement inf
 ormation 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 resolution 
 of 4 km.  This initial deployment of the ground-based prototype LHR has be
 en highly successful and has demonstrated the potential of laser heterodyn
 e radiometry to deliver excellent sensitivity at high spatial and spectral
  resolution in an unprecedented compact package.\n\nTo conclude an outline
  of methods to improve instrument performance and the current developments
  being undertaken will be given.\n
LOCATION:British Antarctic Survey\, Room 330B
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