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Raman Airborne Spectroscopic Lidar
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RASL was developed under the first NASA Instrument Incubator program.
The first laboratory measurements with RASL were taken
in September 2002. It is now being configured for aircraft
flight. It is the first
airborne lidar system to offer the combined measurements
of water vapor mixing ratio, aerosol scattering ratio,
aerosol backscattering
coefficient, aerosol depolarization and liquid
water mixing ratio. |
Description
RASL uses a tripled Nd:YAG laser combined with a 24 inches Dall-Kirkham telescope to make all of its measurements using a single field of view. Photographs of the RASL telescope during its assembly and test are shown below. The RASL final report describes the history of the development of the lidar and shows the first test measurements of the new system.
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RASL Specifications
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| Laser | Continuum 9050Nd:YAG (355 nm), 350 mj/pulse, 50 Hz |
| Telescope | Custom 24” athermal, manufactured by DFM Engineering |
| Data acquisition | 250 Mhz photon counting and 20 Mhz analog detection |
| Range resolution | 7.5 meter |
| Measurements [Molecule/Wavelength (nm)/Bandpass (nm)] | water vapor/407.5/0.25 |
| liquid water/403.2/6.0 | |
| nitrogen/386.7/0.3 | |
| oxygen/375/0.3 or CO2/371.6/0.3 | |
| elastic unpolarized/354.7/0.3 | |
| elastic parallel polarized/354.7/0.3 | |
| elastic perpendicular polarized/354.7/0.3 | |
| Detectors | Hamamatsu R1924 (Raman) and R7400 (aerosol) PMTs |
| Field of View | 0.25 mrad |
Diagrams
Isometric view of current RASL design.
For scale reference, the telescope outer diameter is 28 inches.
Diagram of NASA GSFC's Raman Airborne Spectroscopic Lidar.
(Click on image for full view)
 RASL telescope ready for testing |
 RASL data acquisition electronics |
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Curator:
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Martin Cadirola, Ecotronics Digital Media |
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NASA Official:
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Dr. David Whiteman, David.N.Whiteman@nasa.gov |
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Last Updated:
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Friday, January 20, 2006 |
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