Adaptive (or deformable) mirrors are widely used as wavefront correctors in
adaptive optics systems. The optical calibration of an adaptive mirror is a
fundamental step during its life-cycle: the process is in facts required to
compute a set of known commands to operate the adaptive optics system, to
compensate alignment and non common-path aberrations, to run chopped or
field-stabilized acquisitions. In this work we present the sequence of
operations for the optical calibration of adaptive mirrors, with a specific
focus on large aperture systems such as the adaptive secondaries. Such systems
will be one of the core components of the extremely large telescopes.
Beyond presenting the optical procedures, we discuss in detail the actors,
their functional requirements and the mutual interactions. A specific emphasys
is put on automation, through a clear identification of inputs, outputs and
quality indicators for each step: due to a high degrees-of-freedom count
(thousands of actuators), an automated approach is preferable to constraint the
cost and schedule. In the end we present some algorithms for the evaluation of
the measurement noise; this point is particularly important since the
calibration setup is typically a large facility in an industrial environment,
where the noise level may be a major show-stopper.Comment: 50 pages. Final report released for the project "Development and test
of a new CGH-based technique with automated calibration for future large
format Adaptive-Optics Mirrors", funded under the INAF -TecnoPRIN 2010.
Published by INAF - Osservatorio Astrofisico di Arcetri. ISBN:
978-88-908876-1-