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The application of phase diversity is first invested in simulation to characterize ideal parameters to GPI with faithfully simulated calibration source data. The best working simulation parameters are applied to real GPI data and shown to recover an injected astigmatism. The estimated GPI NCPA are then corrected and the Strehl ratio is improve by ⇠ 5%, although the application is rudimentary and a more thorough correction will be applied in the near future.

For Extremely Large Telescope (ELT) adaptive optics (AO) systems, multiple Sodium Laser Guide Star (LGS) wavefront sensors (WFSs) are required to achieve high sky coverage and diffraction limited performance. However, temporal and spatial variation of the sodium profile causes measurement biases that appear at all time scales and vary between LGS WFSs. To make things worse, optical design residuals, polishing and alignment errors also create non-common-path aberrations (NCPA) that vary between sub-apertures and different WFS, causing LGS WFS to work significantly off null with a nonlinear response. The induced aberrations are consequently non-radially symmetric, even for center launch laser beams with polar coordinate detectors. Natural guide star (NGS) based truth wavefront sensors are often suggested as a method of sensing these LGS WFS aberrations, but a single sensor will suffer strong anisoplanatism that may introduce additional errors. In this paper, we present mitigation strategies and performance estimations based on simulations for the Thirty Meter Telescope (TMT) Narrow Field Infrared AO system (NFIRAOS).

The Real-Time Controller (RTC) for the Thirty Meter Telescope (TMT) Narrow Field Infrared Adaptive Optics System (NFIRAOS) is the software and server hardware that converts wavefront error measurements into wavefront corrector demands, at the heart of the laser guide star multi-conjugate adaptive optics (MCAO) or natural guide star adaptive optics (NGS AO). The RTC takes input from up to six Shack-Hartmann Laser Guide Star wavefront sensors (LGS WFS), one high-order Natural Guide Star Pyramid Wavefront Sensor (PWFS), up to three Shack-Hartmann On-Instrument wavefront sensors (OIWFS) that are located in the client science instruments, and up to 4 on-detector guide windows (ODGW) also in the client instruments. The RTC controls two deformable mirrors conjugated to 0km (DM0) and 11.8km (DM11). DM0 is mounted on a tip/tilt stage (TTS). During the final design phase we performed prototyping to verify that off-the-shelf servers using general purpose CPUs are able to support the maximum 800 Hz frequency at which the RTC is required to operate. We also considered methods to provide live data streams to a graphical user interface without impacting the AO system performance. This paper will discusses the outcome of the impact of jitter and latency on loop speed in our prototype and an overview of the RTC pipeline, including the many “knobs” that can be turned to fine-tune the behavior of NFIRAOS in different observing modes, and under different observing conditions.