  We performed closed-loop lab testing of large-format deformable mirrors (DMs)
with hybrid variable reluctance actuators. TNO has been developing the hybrid
variable reluctance actuators in support for a new generation of adaptive
secondary mirrors (ASMs), which aim to be more robust and reliable. Compared to
the voice coil actuators, this new actuator technology has a higher current to
force efficiency, and thus can support DMs with thicker facesheets. Before
putting this new technology on-sky, it is necessary to understand how to
control it and how it behaves in closed-loop. We performed closed-loop tests
with the Shack-Hartmann wavefront sensor with three large-format deformable
mirrors that use the TNO actuators: DM3, FLASH, and IRTF-ASM-1 ASM. The
wavefront sensor and the real-time control systems were developed for the NASA
Infrared Telescope Facility (IRTF) and the UH 2.2-meter telescope ASMs. We
tested IRTF-ASM-1 on-sky and proved that it meets all of our performance
requirements. This work presents our lab setup for the experiments, the
techniques we have employed to drive these new ASMs, the results of our
closed-loop lab tests for FLASH and IRTF-ASM-1, and the on-sky closed-loop
results of IRTF-ASM-1 ASM.
