From 357568e1fb77afed9dfa203e62da237bf7ce51b3 Mon Sep 17 00:00:00 2001
From: Blaise Thompson <blaise@untzag.com>
Date: Mon, 9 Apr 2018 00:24:18 -0500
Subject: 2018-04-09 00:24

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 opa_phase/chapter.tex | 35 +++++++++++++++++++++++++++++++++++
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+\chapter{Abandon the random phase approximation} \label{cha:rpa}
+
+Recently we've made some measurements that seem to imply phase stability between the fs OPAs.  %
+We've typically assumed that the OPAs have random phase on every shot, making coherent heterodyne
+processes average to zero.  %
+These measurements show that this is a very bad assumption.  %
+
+I've taken the interferogram of OPA1 vs OPA2, Clearly the OPAs remain phase locked for many shots.  %
+In 'over time' I show the spectral phase pattern (D = 500 fs) for 1000 single shot acquisitions
+over 430 seconds in lab time.  %
+The phase does drift, but it is certainly not quickly randomized.  %
+
+I have more data showing:
+How the spectral phase changes over the course of hours.
+How the phase evolves as we scan the OPAs against each-other in color.
+The reproducibility of phase as the OPA motors move away and then return to a given color.
+
+I'll work this data up and send out another email with many more details and thoughts once I have
+time.  %
+This quick note is just to let the group know that we must abandon the 'random phase' assumption
+when thinking about what heterodyne processes can happen as coherent artifacts.  %
+
+\begin{figure}
+  \includegraphics[width=\textwidth]{"opa_phase/cross interference"}
+  \caption[CAPTION TODO]{
+    CAPTION TODO
+  }
+\end{figure}
+
+\begin{figure}
+  \includegraphics[width=\textwidth]{"opa_phase/430 seconds"}
+  \caption[CAPTION TODO]{
+    CAPTION TODO
+  }
+\end{figure}
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