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Gas correlation lidar for methane detectionA new type of DIAL system for the detection of methane in the atmosphere is being developed. The main feature of this lidar is the use of a gas correlation technique to obtain the reference signal by means of a single laser pulse, instead of two shots at different wavelengths. This fact is useful to make measurements on fast moving platforms. To meet the infrared absorption band of methane an optical parametric oscillator (OPO) was used with a LiNbO3 crystal as active element, and a tuning range between 1.5 divided by 4 microns. As known, the major problem to overcome in parametric oscillators are the pump beam quality and the difficulty in reducing the linewidth. The first requirement is met by using, as a pump, a Nd-YAG laser based on a new type of resonator cavity, named SFUR (Self Filtering Unstable Resonator). The laser emits, with high efficiency, near diffraction limited pulsed beams of about 250 mJ of energy, 20 ns of duration at 10 pps of frequency repetition rate. On the other hand, the gas correlation technique allows the operation with a bandwidth as large as 1/cm, which is obtainable using only a diffraction grating as a dispersive element in the OPO cavity.
Document ID
19870000923
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Galletti, E.
(Centro Informazioni Studi Esperienze Milan, Italy)
Zanzottera, E.
(Centro Informazioni Studi Esperienze Milan, Italy)
Draghi, S.
(Centro Informazioni Studi Esperienze Milan, Italy)
Garbi, M.
(Centro Informazioni Studi Esperienze Milan, Italy)
Petroni, R.
(Centro Informazioni Studi Esperienze Milan, Italy)
Date Acquired
August 13, 2013
Publication Date
August 1, 1986
Publication Information
Publication: NASA. Langley Research Center 13th International Laser Radar Conference
Subject Category
Geophysics
Accession Number
87N10356
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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