Title: Design, Development And Evaluation Of A 2-Micron Differential Absorption Lidar For Profiling CO2
Primary Author: Ismail, Syed
Organization: NASA Langley Research Center
Co-Author(s): Grady J. Koch, Tamer F. Refaat, M. Nurul Abedin, Upendra N. Singh, Manuel A. Rubio, Terry Mack, Bruce Barnes, Kenneth J. Davis, and Charles Miller

This paper presents the design, development, and field testing of a high sensitivity ground-based Differential Absorption Lidar (DIAL) system that was developed under the NASA Instrument Incubator Program. The investigation presents a significant advancement towards the development of future CO2 profiling technology as it incorporates key elements of technologies needed for a future development of global CO2 measuring systems including: (1) 2-mm laser technologies that have been developed under a number of NASA programs including the Laser Risk Reduction Program (LRRP) (2) A novel high quantum efficiency (QE), high gain (without excess noise factor), and low noise phototransistor, and (3) Direct detection DIAL system using a large collection area receiver that is insensitive to speckle and coherence length effects from atmospheric turbulence that influences heterodyne detection systems. The objective of the project was a system TRL of 4, and the goal was TRL 5. Development and testing of the laser, new detector, and receiver systems during the project, integration into a complete lidar system into a trailer, field testing of system at West Branch, IA and comparison of the lidar CO2 measurements with in situ sensors (showing good agreement with the in situ tower sensors) the system was advanced to a TRL of 5.