Spatial-Temporal Control Applied to Atmospheric Adaptive Optics

ABSTRACT: MZA, teamed with UCLA and Notre Dame proposes the design, development, verification, and demonstration of a real-time adaptive optics (AO) wavefront control processor implementing the linear time-invariant (LTI) predictive control algorithm investigated in Phase I. We will also conduct WaveTrain engineering simulations for an aircraft tactical laser system operating in transonic flight to address real-world physical phenomena such as realistic aero-optical effects, beacon illuminator propagation, and limited SNR which influence the operation of the LTI predictive controller. A key aspect of the design of the AO processor is to provide an interface of the hardware to WaveTrain models, thereby allowing our real-time implementation to be tested directly in the simulated environment. We will develop a FPGA-based AO controller solution presenting a standard camera interface and which couples well with high-speed deformable mirrors (DMs) currently under development for AFRL/RD and HEL-JTO. We will conduct laboratory tests with these DMs to verify proper AO operation with update rates of at least 10 kHz. We will use the AO processor and DM hardware from our laboratory verification testing to demonstrate AO compensation at the Notre Dame wind tunnel facility, including flow conditioning which is synergistic with predictive AO control. BENEFIT: Robust adaptive optics compensation of aero-optics and free-stream turbulence for tactical aircraft-based lasers requires predictive control methods which will address performance degradation resulting from finite sample rate of wavefront sensors and the associated latency. Our Phase II program will result in a real-time, high-speed, AO wavefront control processor implementing LTI predictive control of compact high-speed DMs. The resulting AO systems will provide high-quality atmospheric and aero-optical disturbance compensation without placing artificially high burdens on AO illuminator technology which may be difficult to achieve in a practical system. Such a solution has immediate use in near-term electric laser system designs for aircraft platforms such as the Air Force ELLA program. The Army"s mobile THEL program would also benefit from this technology. Offering a well-integrated processor and controller for high-speed AO applications resulting from this Phase II project will enable a commercial-grade AO product for aircraft applications, including beam control, imaging, laser illumination/designation, and laser communications. These systems could also be used in solid-state resonator beam clean-up where aberrations from gain media coolant flow limit available beam quality at higher laser power levels.