Update on the Development of a Multifunctional Fiber Laser Lidar for CO2 and O2 Detection

The Multifunctional Fiber Laser Lidar (MFLL) is an Intensity Modulated (IM), Continuous Wave (CW), Integrated Path Differential Absorption (IPDA) lidar system that was developed by ITT Exelis and has been under evaluation for the ASCENDS mission by NASA Langley Research Center (LaRC) since 2004. The MFLL has been deployed in 12 different flight campaigns, on three different aircraft, for the evaluation of the instrument to retrieve column integrated CO₂. Exelis has also developed an O₂ channel using a custom fiber Raman amplifier developed under a NASA ACT grant, which flew for the first time in July 2011 on board the NASA DC-8 aircraft. Over the past year Exelis has been working with NASA LaRC on several efforts to advance the technologies required for scaling the MFLL measurement concept to space, and validating instrument performance models. The technology development has been funded through NASA ESTO's IIP program and has been focused on advancing the detector subsystem to enable autonomous, high bandwidth operation (~5MHZ) while reducing the size, weight and power of that subsystem. We are also working to demonstrate the ability to scale the system transmitted optical power to levels required for high altitude platforms such as the Global Hawk and for space applications. For the MFLL IM-CW approach this is accomplished by seeding additional Erbium Doped Fiber Amplifiers (EDFA's) with the IM fixed wavelength signals and combining them in the far field. NASA LaRC, Exelis and Welch Mechanical have been working on a unique distributed aperture telescope design that will combine three telescopes using fibers that come together into a bundle, and is then imaged onto a single detector. Additional technology being incorporated into this IIP has been performed through NASA Small Business Innovation Research Program grants, managed by LaRC, to advance the seed laser and modulation components and to develop an alternative O₂ amplifier based on direct amplification. Limited retrieval sensitivity studies and science impact studies have also been part of the IIP effort and will be discussed.

The goal of the IIP development is to demonstrate the technologies required for migration the MFLL instrument to a Global Hawk platform. Furthermore, these technologies will demonstrate the ability of the airborne instrument to be scaled to space. A review of progress on each of these efforts will be given along with initial results from laboratory and field testing of some of these technologies in preparation for an upcoming DC-8 Flight campaign scheduled for February – March 2013.