SCExAO: A prototyping platform for ELTs extreme-AO

Direct imaging and spectroscopy of habitable planets will be possible on ELTs if they can reach fi1e-8 contrast at 10-40 mas separation. This performance level, while conceptually within reach, is several orders of magnitude beyond what current ExAO systems deliver and relies on novel approaches/technologies. On-sky prototyping and validation of these new approaches is essential prior to instrument deployment on ELTs. The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system is a welcoming platform for exper-imentation and can play a valuable role in this process. New hardware and software approaches can first be validated with the internal source, providing an incremental path to on-sky system-level validation. Thanks to multiple dichroic/filter wheels, light can be directed simultaneously to multiple WFSs and cameras by wavelength or greyscale splitting. The software environment is highly modular and has been optimized to facilitate deployment of new al-gorithms. Real-time access to all sensor data and calibrated telemetry is provided. Example code can easily be adapted, removing the burden of coding low-latency hardware communication and calibration. Thanks to accurate and stable system-wide timing, open-loop wavefronts are reconstructed in real-time, allowing users to easily deploy predictive filters and test high speed (kHz) speckle modulation and control schemes. In 2017, SCExAO's RTC offers 100 Tops computing power. The software architecture is largely hardware-independent, and open-source development will be shared with other AO systems.