Hannover 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
UP: Fachverband Umweltphysik
UP 1: Atmospheric Spectroscopy
UP 1.3: Vortrag
Dienstag, 9. März 2010, 15:00–15:15, M 11
Optical-Feedback Cavity Enhanced Absorption Spectroscopy and its Application to Water Vapour Traces — •Jan Christoph Habig1,2, Jan Meinen1,2, Harald Saathoff2, and Thomas Leisner1,2 — 1Institut für Umweltphysik, Im Neuenheimer Feld 229, D-69120 Heidelberg — 2Atmosphärische Aerosolforschung (IMK-AAF), Karlsruher Institut für Technologie (KIT), D-76344 Eggenstein-Leopoldshafen
A new spectrometer for water vapour concentration measurements at the AIDA chamber at KIT based on optical feedback frequency locking of a DFB laser diode to a V-shaped external optical cavity is being presented. It is shown how feedback related effects such as linewidth narrowing and frequency stabilization of the diode laser can be used to overcome the generally known contradictoriness of long effective light paths within the cavity and high intensity transmission.
The instrument built is operating in the near infrared spectral region and realizes an effective path of 3 km. The spectral resolution is 0.01 cm−1 and the spectral range available by current tuning of the laserdiode is 1.06 cm−1. The noise equivalent signal strength is reached at water vapour concentrations of 1.1 ppb at standard conditions and at a time resolution of 100 s. The corresponding absorption coefficient is αmin=2.7· 10−8m−1 whereas the dynamic range of the instrument covers more than four orders of magnitude.