  The MagAO-X instrument is a new extreme adaptive optics system for
high-contrast imaging at visible and near-infrared wavelengths on the Magellan
Clay Telescope. A central component of this system is a 2040-actuator
microelectromechanical deformable mirror (DM) from Boston Micromachines Corp.
that operates at 3.63 kHz for high-order wavefront control (the tweeter). Two
additional DMs from ALPAO perform the low-order (the woofer) and
non-common-path science-arm wavefront correction (the NCPC DM). Prior to
integration with the instrument, we characterized these devices using a Zygo
Verifire Interferometer to measure each DM surface. We present the results of
the characterization effort here, demonstrating the ability to drive tweeter to
a flat of 6.9 nm root mean square (RMS) surface (and 0.56 nm RMS surface within
its control bandwidth), the woofer to 2.2 nm RMS surface, and the NCPC DM to
2.1 nm RMS surface over the MagAO-X beam footprint on each device. Using
focus-diversity phase retrieval on the MagAO-X science cameras to estimate the
internal instrument wavefront error (WFE), we further show that the integrated
DMs correct the instrument WFE to 18.7 nm RMS, which, combined with a 11.7%
pupil amplitude RMS, produces a Strehl ratio of 0.94 at H$\alpha$.
