Three Dimensional Turbulence Measurement System based on Green`s Function Inversion

Atmospheric turbulence is too poorly modeled to predict the performance of a high energy laser (HEL) system in the field. Experiments conducted so far did not produce the needed three dimensional profiles to model phenomena such as turbulence anisotropy and inhomogeneity, variations of inner-scale and outer-scale of turbulence, and strong departures from Gaussian statistics. During the first phase of this SBIR project, Optical Physics Company (OPC) demonstrated the feasibility of its approach for 3D turbulence measurement through analysis, simulation and laboratory demonstration. A laboratory experiment optically scaled to match a 28 km range from airplane to ground was assembled. Ability to obtain high resolution turbulence profiles in three dimensions in air-to-ground and air-to-air scenarios has been verified. The overall maturity of the technology now stands at TRL 4. During Phase II a complete 3D turbulence profiling system will be demonstrated outdoors across a 100-500 m horizontal path using an eye-safe 1.55 micron laser. The demonstration conditions shall be scaled to match an airborne turbulence profiling system scenario in order to predict the performance of a flight system with high fidelity and tested over a broad range of imaging conditions day and night. BENEFIT: The 3D Turbulence Sensor has been developed to provide a major leap in our understanding of turbulence phenomena and how to model them analytically. The system is critically important to the success of current and future lasercom and tactical HEL systems by enabling them to predict and optimize performance to a much higher accuracy. In Phase III, a flight ready transmitter and sensor can be assembled to verify correct operation in an inexpensive flight test. The transmitter module would be mounted on a modified jet aircraft, which would fly and illuminate a ground-based receiver. Not only would end-to-end operation be verified, but 3D turbulence data for 10 km of atmosphere would be available for the first time.