\section{PSD\_monitor\_coh: The coherent PSD monitor}
\index{Monitors!Position sensitive detector (PSD), coherent}
\mcdoccomp{monitors/PSD_monitor_coh.parms}

The component \texttt{PSD\_monitor\_coh} closely resembles its parent the \textbf{PSD\_monitor}, 
and also propagates the photon ray to the detector
surface in the $(x,y)$-plane, where the detector window is set
by the $x$ and $y$ input coordinates.
The coherent PSD monitor, though, is also sensitive considers the phase of the photon ray
and emits not one but two datafiles, where one (\textit{filename}.abs) represents the coherent intensity 
and the other (\textit{filename}.arg) the phase of the collected beam.

The first output file (.abs) from \texttt{PSD\_monitor\_coh} is the integrated counts, $n, I, M_2$,
as well as three two-dimensional arrays of counts: $n(x,y), I(x,y), M_2(x,y)$.
These arrays are written to a file, \verb+filename.abs+, and can be read e.g. by the tool
\textbf{mxplot}, see the system manual.
Likewise, the second output file (.arg) contains the integrated phases, and are written to the file 
\verb+filename.arg+
