Temporal Error Minimization In Adaptive Optics Control Loop Mark Nishimura Internship Site: Subaru Telescope (NAOJ) Mentor: Olivier Guyon

Outline Subaru Adaptive Optics Error Minimization Results

Subaru AO System Next Generation AO System Three elements: Wave-Front Sensor Curvature Sensor Control Computer Deformable Mirror Bimorph Mirror

Adaptive Optics Simulation Created in C one actuator simulation of AO system Realistic Simulated Atmosphere

Adaptive Optics Simulation Photon Noise Time Delay (125 micro sec) DM Response

Project Test new ideas to improve performance Increasing DM update frequency Average the number of photons in time Smith Compensator

DM Updates Send updates twice as often to DM Limitation Frequency of Vibrating Membrane

Average Photon Count I(+)-I(-) / I(+)+I(-) = Curvature I(+)-I(-) / I(ave)+I(ave) = Curvature Decreases the effect of photon noise Results Improvements with guide stars dimmer than Magnitude 9

Smith Compensator (Predictor) Prevents over correction due to delay DM Position DM Signal

Results Significant improvements below 80Hz Limitations DM Response

Future Improvements Find a clever way to drive DM to limit oscillations

Acknowledgments Subaru Telescope (NAOJ) Olivier Guyon Hideki Takami This project is supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST - 9876783.