From 4ddc0bcecdd172e6fbed0df2e80dfc7663b6ab73 Mon Sep 17 00:00:00 2001
From: Blaise Thompson <blaise@untzag.com>
Date: Sun, 12 Nov 2017 18:51:13 -0600
Subject: structure

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+\chapter{Hardware}  % -----------------------------------------------------------------------------
+
+In this chapter I collect some of the specific hardware contribution details that do not belong in
+the body of the dissertation.  %
+
+\section{Adjustable periscopes}  % ----------------------------------------------------------------
+
+OPAs output horizontal or vertical polarizations according to which tuning process is used.  %
+Our experiments are opinionated about polarization, so some strategy for aligning polarization is
+necessary.  % TODO: cite opinionated about polarization
+In addition, it is useful to bring all excitation beams to the same height.  %
+To this end, I designed and constructed two adjustable periscopes.  %
+Each periscope is designed to bring OPA output to table height standard (5 inches) while either
+keeping or switching polarization.  %
+Both polarization configurations take the same path length, so source polarization can be switched
+without large changes to zero delay.  %
+All of this is done with just two (switched polarization) or three (kept polarzation)
+reflections.  %
+A picture of these periscopes is shown in \ref{f:periscope}.  %
+
+\begin{figure}[htp!]
+	\centering
+	\includegraphics[width=\textwidth]{"hardware/periscope"}
+	\label{f:periscope}
+	\caption{CAPTION TODO}
+\end{figure}
+
+While these periscopes are easy to align, their unique design means that it is not necessarily
+obvious what the correct strategy is.  %
+The following strategy will always converge:
+\begin{enumerate}
+  \item use two ``magic'' apertures along the output beamline
+  \item in flipped polarization (two mirror configuration):
+    \begin{itemize}
+      \item use the stage (green X, Y) to align near aperture
+      \item use the upper mirror (yellow TA, TB) to align far aperture
+      \item iterate above
+    \end{itemize}
+  \item in kept polarization (three mirror configuration):
+    \begin{itemize}
+      \item use stage X (green X) and upper mirror height (yellow TC) to align near aperture
+      \item use lower mirror (pink SA, SB) to align far aperture
+      \item iterate above
+    \end{itemize}
+\end{enumerate}
+The kept polarization alignment is derivative of the fixed polarization alignment.  %
+One must ensure that the fixed polarization is correctly aligned at all times.  %
+  
+Mirror B (aqua) is magnetically mounted to switch between polarization conditions.  %
+Ensure that the lower turning mirror (pink) does not bump into mirror B (aqua) in polarization
+swtiching configuration.  %
+The lower turning mirror is on a rail (pink SC).  %
+This rail is a rough adjust for the same degree of freedom as pink SA.  %
+Adjust the rail only to ensure that the beam is roughly centered on the free aperture of the
+turning mirror.  %
+
+The first reflection is often accomplished using a wedge, as OPA output may be strong enough to
+damage downstream optics.  %
+This optic can and should be replaced if more of the OPA output is desired on the table (keeping
+damage thresholds in mind).  %
+
+\subsection{Wedge polarization preference}
+
+TODO: wedges will be more efficent at reflecting horizontal / vertical at 45 degrees
+
+\section{Automated transmissive filters}  % -------------------------------------------------------
+
+TODO
+
+\section{Electronics}  % --------------------------------------------------------------------------
+
+TODO
\ No newline at end of file
-- 
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