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\section{Introduction}
The Automated Alignment System (AAS) and Back End Active Stabilization of Shear and Tilt (BEASST) together serve to align the beam trains in the MROI and to keep these aligned during the night. An design for the AAS
has been developed to the level of went through a Conceptual Design Review (CDR) and
additional development has been performed since then
to prototype some subsystems
of the AAS. have been prototyped. We propose here a modification to the AAS
concept which will allow the existing goals to be met
but which would allow while addressing drifts in alignment during the night
to be addressed much more
robustly using BEASST. rapidly and robustly. At the same time, some of the constraints on the BEASST system can be relaxed, allowing a
more performant higher-performance system to be built more quickly.
\section{Functional requirements}
The function of the combined AAS and BEASST systems (hereafter
collectively referred
to as
just ``the
AAS'') AAS'' since they can be considered to be a single system addressing alignment needs) can be briefly described as:
\begin{enumerate}
\item When a new beam train is installed or configured, the AAS must allow for coarse (and possibly manual) alignment of the beam train to allow an alignment beam to pass between the beam combining area (BCA) and the unit telescope mount (UTM) without vignetting.
\item At the beginning of each observing
night the beam train, night, the AAS must
align re-align the beam train so that beams of starlight arriving at the beam combiners meet the tilt and shear error budget.
\item During the night, the AAS must make fine adjustments to the alignment so that the tilt and shear error budget is maintained in the presence of thermal
and other drifts (this requirement was originally delegated to BEASST). drifts.
\item When a new beam train is installed or configured, the AAS must allow for measurement of the "piston" term due to the optical path between the beam combiners and the
telescopes. telescopes, in order to allow for rapid acquisition of stellar fringes.
\item At the beginning of the night, the AAS must allow the pathlength differences between the fringe tracker and the science instrument to be
measured. measured so that these can be equalized.
\end{enumerate}
\section{Outline of the existing scheme}
\section{Proposed modification}
\section{Advantages and disadvantages}
\section{Recommendation}