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Proceedings Paper

Automated Alexandrite Transmitter For Airborne Dial Experiments
Author(s): John J Degnan
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Paper Abstract

The present paper summarizes the key characteristics and development status of an automated dual Alexandrite laser transmitter to be used in a series of airborne water vapor DIAL experiments on the NASA ER-2 high altitude research aircraft. The Lidar Atmospheric Sensing Experiment, or LASE, is a joint effort of the Langley Research Center (LaRC) and the Goddard Space Flight Center (GSFC) with the latter center being responsible for the transmitter. The transmitter consists of five separate subsystems - a pressurized Dual Laser Head (DLH) containing two Alexandrite lasers, a Laser Control Unit (LCU), a Laser Thermal Unit (LTU), and two Lamp Driver Units (LDU's) - and weighs approximately 330 lbs. Each laser utilizes three computer- controlled tuning elements - a five plate birefringent tuner, a thin solid etalon, and a thick solid etalon - to perform inflight tuning or wavelength scans and to hold the radiated wavelength within 0.5 pm of the desired value with the aid of an external high precision wavemeter. The transmitter is designed to operate and maintain its alignment over a wide range of environmental conditions in the aircraft Q-bay compartment. Major reductions in system size and weight, relative to commercial alexandrite lasers, were necessary to meet LASE Project requirements. Furthermore, since the Q-bay experiences ambient pressure variations between 3.5 and 15 psi and ambient temperature variations between 15° and 40°C, the transmitter will be tested in an environmental chamber prior to delivery to the Project. At the present time, subsystem performance tests have been successfully completed on all flight units with the exception of the laser head itself which has undergone only breadboard level tests. In addition, the LTU and LDU's have successfully passed 5 g-rms random vibration tests.

Paper Details

Date Published: 12 April 1988
PDF: 6 pages
Proc. SPIE 0889, Airborne and Spaceborne Lasers for Terrestrial Geophysical Sensing, (12 April 1988); doi: 10.1117/12.944254
Show Author Affiliations
John J Degnan, NASA Goddard Space Flight Center (United States)

Published in SPIE Proceedings Vol. 0889:
Airborne and Spaceborne Lasers for Terrestrial Geophysical Sensing
Frank Allario, Editor(s)

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