Adaptive Optics for Extremely Large Telescopes 4 – Conference Proceedings

We report the progress of the Canary High-Order Upgrade (CHOUGH) addition to the CANARY AO experimentat the 4.2m WHT telescope, ORM, La Palma. While CANARY has been developed to investigate severaltomographic congurations relevant to the E-ELT, it also has the ability to host guest AO instruments andprovide them with relevant infrastructure. CHOUGH is a self-contained AO bench that integrates into CANARY,via an external feed of light, to provide a Strehl 0:5 in the visible. Within CANARY, CHOUGH picks o lightafter a 240-actuator deformable mirror and delivers the on-axis beam into the internal relay which feeds varioussub-systems. These are include pick-o optics, a ADC, and 1k-actuator DM, all of which are part of an internalrelay to three instruments: a spatially-ltered SH WFS, a calibration interferometer, and a narrow-eld imagingcamera. As CHOUGH is constructed on a separate breadboard, the components are self-contained and can beintegrated and operated separately from CANARY. In this paper the progress on the design, procurement, andperformance of the CHOUGH sub-systems and the experiment as a whole is given. Attention is given to thealgorithms that will be used and the control methods that will be utilized on-sky. The modular nature of thedesign leads to potential upgrade paths and a brief discussion is made of new directions of on-sky research thatcould be carried out with replacement sub-systems and new instrumentation.