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AROTEL Detector Package for the SOLVE Mission
Time period
May 1999 to July 1999
Project description
Airborne Raman Ozone, Temperature, and Aerosol Lidar (AROTEL) is a Lidar instrument for making measurements of ozone, temperature, and aerosols in the atmosphere. AROTEL consists of a transmitter (laser), receiver, and data acquisition electronics. AROTEL's users wanted to upgrade the system before taking the instrument into the SOLVE (SAGE III Ozone Loss Validation Experiment) deployment on-board the DC-8 aircraft.
The receiver package for the instrument needed to be redesigned. The new design used 10 Photomultiplier Tubes (PMT) each looking at a specific wavelength returned by the atmosphere. The wavelengths are separated by optical beam splitters and filters in front of each PMT further block unwanted wavelengths.
A modular design was desired so that additional channels could be added in the future. This gives the system the ability to quickly be modified to detect a different wavelength or to add more wavelengths. The package I designed uses 10 lens barrel - PMT mounts. Two barrels attach to each beam splitter mount (shown in light bluish-purple in the top image).
Computer rendition of AROTEL
receiver on 2'x2' breadboard
Photograph of assembled AROTEL receiver prior to
adding optics and electronics
Five of these subassemblies make up the ten channels of the system. A chopper wheel and deformable mirror are contained inside of the boxes holding the ten channels together. These two components help to attenuate the strong reflections from the laser beam as it passes through the aircraft window and the atmosphere close to the aircraft. These steps prevent the most sensitive detectors from saturating. The boxes, barrels, and beam splitter mounts are all mounted to an intermediate base-plate shown in gray in the top image. This keeps all of the elements in this receiver package rigidly aligned. Finally, the package is mounted to a 2-foot (61-centimeter) x 2-foot x 2-inch (5.1-centimeter) optical breadboard along side a receiver package designed and built by Langley Research Center.