Multi-wavelength Raman Lidar
configuration and preliminary
testing results
Click here for full view
Diagram of the laser power
stabilization system
Click here for full view
Comparison of current vs.
project transmission
throughput for narrow
band interference filter
Click here for full view
Technology Development
In addition to the development of complete lidar systems such as SRL and RASL for use in measurement campaigns, the Raman lidar group is involved in the development of more experimental measurement systems as well component technology to improve lidar measurements. The group is involved in the development of the following measurement systems and technologies:
- Multi-wavelength Raman lidar
- Laser power stabilization sub-system
- High transmission, narrow band interference filters
- Bore site alignment sub-system
To better understand and develop satellite retrieval algorithms of the effect of aerosols on clouds, we need to improve knowledge and understanding of basic cloud physics processes. The Raman Lidar measurements will be used to provide profiles of aerosol characteristics such as volume density and index of refraction as well as cloud liquid water, cloud droplet radius and droplet number density. The Lidar retrievals will be studied in a cloud physics context through the use of an existing cloud physics model that uses cloud condensation nucleus (CCN) distributions and updraft velocities to grow cloud droplets. The instrument specifications for this type of measurements are as follows:
|
Laser Type
|
Tripled Nd:YAG laser – 17.5 W |
|
Telescope
|
0.6 meter |
|
Optical channels
|
354.7 nm, 387 nm, 402 nm, 407 nm, 532 nm, 607 nm, 1064 nm |
|
Data acquisition
|
Combined analog to digital (12-bits at 50 Mhz) and 250 Mhz photon counting |
Laser power stabilization sub-system
Laser power variations influence all laser applications including surgery and remote sensing. Some applications must be performed under thermal or mechanical stresses implying that laser powers will vary. An automated feedback system that maintains the power levels is needed. We are developing a self-contained laser power stabilization feedback system for retrofitting on commercial Nd:Yag lasers such as those marketed by Continuum and other laser manufacturers.
High-transmission narrow band interference filters
As co-investigators with John Potter of Barr Associates, Inc. and funded through the ESTO Advanced Component Technology program, we are involved in the specification, fabrication and testing of ultra-narrow UV interference filters. The goal of this activity is to develop interference filters with the same blocking characteristics as currently available filters but with up to twice the transmission as is currently available in a 0.1 nm filter. We will characterize this filter for central wavelength and passband width using a Fourier Transform Spectrometer. We will also verify the performance of the filter through atmospheric measurements of aerosol extinction.
Bore site alignment sub-system
Information about this component will be available soon.
|
Curator:
|
Martin Cadirola, Ecotronics Digital Media |
|
NASA Official:
|
Dr. David Whiteman, David.N.Whiteman@nasa.gov |
|
Last Updated:
|
Friday, January 20, 2006 |
|
|
|
