The National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST) has made the transition from construction to science operations. It is currently operating with a “classical” single-conjugate Adaptive Optics (AO) system, which will be upgraded to a multi-conjugate AO (MCAO) system within the next few years. One of the key challenges for the DKIST MCAO system will be procuring a suitable Deformable Mirror (DM) to replace the current M7 flat, which is conjugate to 11.2 km.

The DM must be large in size with an elliptical clear aperture 884 by 625 mm. It must also have a high actuator density, with actuator spacings smaller than 11 mm. Additionally, it must have an actuator rise time of 100 µs and an update rate greater than 2 kHz. We have identified the surface-parallel actuated silicon carbide DMs made by Northrop Grumman’s AOA Xinetics (AOX) as a likely candidate to meet our requirements. However, there are some challenges that come with using this technology for the DKIST MCAO system. We must design our controller to avoid exciting resonant modes in the mirror. We also must minimize actuator saturation or it will become the dominant error term in our wavefront fitting error.