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author | Blaise Thompson <blaise@untzag.com> | 2018-04-09 14:01:34 -0500 |
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committer | Blaise Thompson <blaise@untzag.com> | 2018-04-09 14:01:34 -0500 |
commit | 102e605b714e61cffe639fa59e0a69458bc0daca (patch) | |
tree | 88b7ff2069c5a9d50619a79e45b6ec64c500e9d1 /active_correction | |
parent | f4581b99e4b391b6a1ebedf4ad147fcc8d6c40ce (diff) |
2018-04-09 14:01
Diffstat (limited to 'active_correction')
-rw-r--r-- | active_correction/chapter.tex | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/active_correction/chapter.tex b/active_correction/chapter.tex index 6e773ec..f4447d0 100644 --- a/active_correction/chapter.tex +++ b/active_correction/chapter.tex @@ -44,8 +44,50 @@ I hope to show that active correction is a particularly useful strategy in MR-CM [FIBRILLATION]
+\clearpage
\section{Spectral delay correction} % ============================================================
+As a frequency domain technique, MR-CMDS requires automated tuning of multiple OPAs. %
+These OPAs generate pulses, which are then manipulated and directed into a sample of interest. %
+Crucially, the relative arrival time of each pulse must be carefully controlled in the context of
+the MR-CMDS experiment. %
+Unfortunately, changing the output frequency also changes the optical path length, meaning that
+there is some unavoidable coupling between delay and frequency axes. %
+Because we have full control over delay through delay stages, we can correct for this phenomenon by
+choosing a different zero delay \emph{offset} for each OPA output color. %
+This strategy has been dubbed ``spectral delay correction''. %
+
+Spectral delay correction (SDC) is certainly the longest running active correction strategy employed
+within the Wright Group. %
+SDC was first implemented by Schuyler Kain within his COLORS acquisition software. [CITE] %
+COLORS' implementation was hardcoded for one particular OPA / delay configuration---it wasn't until
+PyCMDS that fully arbitrary SDC became possible through the autonomic system (see section ...). %
+Erin Boyle ``backported'' similar functionality into to ps\_control, although her implementation
+allowed only for a simple, first order linear correction. %
+
+Sometimes, spectral delay can be corrected for after-the-fact. %
+Post processed spectral delay correction can only be done if all relevant delays are scanned during
+the experiment. %
+A common example is transient absorption, where the single delay axis is typically scanned at each
+color coordinate. %
+A special method of \python{Data}, \python{Data.offset} is designed to do the necessary
+interpolation for \emph{post hoc} SDC. %
+
+In many experiments spectral delay must be actively corrected for. %
+Fully coherent experiments do
+
+It has been found that SDC is necessary for each individual scanned OPA, and for each separate path
+when pulses from a single OPA are split. %
+The difference between different paths is typically small, but enough to move pulses a noticeable
+amount relative to each-other. %
+For this reason, SDC for split OPAs is a multidimensional problem, which in principle requires a
+multi-dimensional acquisition to fully record. %
+In practice, however, these corrections are recorded iteravely. %
+
+[ALTHOUGH ACTIVE, CAN SOMETIMES BE CORRECTED FOR IN POST: SEE WRIGHTTOOLS.OFFSET]
+
+[SDC IN CONTEXT OF WHITE LIGHT]
+
\begin{figure}
\includegraphics[width=0.45\textwidth]{"active_correction/sdc_before"}
\includegraphics[width=0.45\textwidth]{"active_correction/sdc_after"}
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