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Instrument: LASE : Lidar Atmospheric Sensing Experiment
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Description
The Lidar Atmospheric Sensing Experiment (LASE) program was initiated
as an effort to produce an autonomous system for measuring water vapor
levels from airborne and spaceborne platforms using LIDAR technology.

The LASE Instrument:

The transmitter consists of a Ti:sapphire laser pumped by a double
pulsed Nd:YAG laser. The frequency of the Ti:sapphire laser is
controlled by injection seeding using a diode laser that is frequency
locked to a water vapor line in the 815-nm region. The "on" and "off"
wavelengths are separated by less than 70 pm. The laser pulses are
sequentially transmitted with about 400 microseconds separation. This
permits the use of the same avalanche photodiodes (APD) for detecting
the lidar returns. The use of low and high light level APD's provides
linear response to atmospheric and cloud/ground returns,
respectively. Lidar returns at 5 Hz are digitized and recorded, and
when possible, the data are telemetered to the LASE ground station for
real-time processing and experiment control. Operation with strong and
weak absorption regions of a preselected water vapor line can be made
during the mission to optimize the measurement of water vapor in
different altitude regions.

The LASE system has proven to be a reliable, accurate, and sensitive
water vapor profiler with the ability to measure water vapor mixing
ratios over a large dynamic range (0.01 g/kg to 20 g/kg). Aerosol
backscatter ratios can be measured from ground to 20 km with a
vertical resolution of 30 m and a horizontal resolution of 40 m.

Additional information available at
http://asd-www.larc.nasa.gov/lase/ASDlase.html

[Summary provided by NASA]