MANUFACTURERS OF CUSTOM, HIGH PRECISION INSTRUMENTATION AND SUPPORT EQUIPMENT
Projects
- Lidar and Directed Energy Components
- Complete Lidar/Active Instruments
- Raman Airborne Spectroscopic Lidar (RASL)
- LVIS
- Micro-Pulse Lidar
- THOR Lidar
- Phasers - Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing
- HARLIE (Holographic Airborne Rotating Lidar Instrument Experiment) Hemisphere Scanning Stage
- High Spectral Resolution Lidar (HSRL)
- GOLD
- 2-micron CO2 Lidar
- DAWN AIR1
- Support Equipment
- Aircraft Installations
- ER-2 Doppler Radar Data System Enclosure
- Cloud Radar System Data System Enclosure
- King Air Rear Cargo Area Riser plate and electronics racks
- King Air 4-bay electronics rack with shock isolation
- RSP Instrument installation in King Air
- HSRL instrument installation
- 400mm aperture window port for King Air HSRL-247-X
- Raman Airborne Spectroscopic Lidar (RASL)
- RASL segmented window and external heat exchanger
- LVIS installation in King Air
- MASTER installation in King Air
- HiWRAP in WB-57
- Complete Passive Optical Instruments
- RF Instruments
- Single Point Diamond Turning
- Space-based Instruments
Raman Airborne Spectroscopic Lidar (RASL)
Time Period
For scale reference, the telescope outer diameter is 28"
January 2000 to Present
Project Description
The Raman Airborne Spectroscopic Lidar (RASL) consists of a 15W ultraviolet laser, a 24-inch (61-centimeter) diameter Dahl-Kirkham telescope, a custom receiver package, and a structure to mount these components inside an aircraft. Both the DC-8 at NASA Dryden and the P3 at NASA/Wallops are aircrafts that could carry RASL. The system is unique because it requires the largest window ever put into either of these aircraft. A fused-silica window, diameter of 27 inches (68.6 centimeters) and 2.375 inches (6 centimeters) thick is needed to withstand the pressure and temperature differentials at a 50,000-foot (15.2-kilometer) altitude.
The atmospheric returns for a Raman Lidar are orders of magnitude weaker than for systems using other Lidar techniques. This makes the RASL receiver package very sensitive to stray light since the signal collected by the telescope is already very weak. We have designed multiple levels of light blocking into the receiver package to minimize the number of stray photons reaching the sensitive photo multiplier tubes (PMTs). There are also many features to speed the calibration process and allow future automation. This should improve the quality and quantity of data collected compared to previous Raman Lidars.
Challenges and Lessons Learned
This is the first extremely stray-light sensitive design that we have tackled. The skills learned during this design will help to maximize future projects' performance.
Packaging the large components of RASL in the small space available in the DC-8 poses a challenge as one can see from the rendered picture. Some of the issues that must be considered through all aspects of the RASL design are as follows:
- How to install and assemble the instrument inside the aircraft
RASL in the P3 cabin - How the operator will interact with the instrument
- How to ensure operator safety in the confined space
Photograph of the DC-8 cargo bay -- RASL's future home