AFRL Funds Research for High-Power Airborne Laser Systems

  • Published
  • By Air Force Office of Scientific Research
  • AFOSR
Arlington, Va. --  
AFRL is funding research at the University of Notre Dame to advance the knowledge of near-field aero-optic deviations and their effect on directed energy. A team at the university is researching the effect of aero-optics and its implication to laser communication applications and other optical research initiatives. Successful development of airborne laser weapons or communications systems will entail the development of adaptive optic or aerodynamic solutions to the corrupting effects of aero-optics.

Aerodynamic flows around aircraft structures induce density variations in the boundary layer flows and slipstream. The interaction of these density variations with a laser beam (aero-optics) can severely alter the beam characteristics, making it difficult or impossible to focus laser power on distant objects or transmit laser communications signals from a flight vehicle.  To conduct the computational analysis, the team plans to employ an advanced, large-eddy simulation code that can capture the density fluctuations and thus the changing index of refraction, which is important for accurate predictions regarding the effect of flow control on aero-optical deviations. 

Engineers at Notre Dame are building a new closed-loop wind tunnel with a 3-ft square test section with high-optical-quality access and low-intensity turbulence in order to complete wind tunnel experimentation prior to flight test. The team will conduct flight tests in two Cessna Citations flying in formation. These aircraft are capable of achieving Mach 0.5 (380.7 mph, or half the speed of sound) in straight, level flight and Mach 0.71 (532.5 mph) in a descent. 

This research culminates decades of investigation into the relationship between fluid dynamic mechanisms (e.g., density gradients) existing in the presence of pressure wells and the refraction index of fluid media. When evaluation of these phenomena was first introduced over two decades ago, scientists considered it trivial. The scientific community now views research of these dynamic interactions as crucial to assuring the success of Air Force directed energy and laser communication technologies.