Position-sensitive monitor with phase integration.
Author: Erik Knudsen
Origin: Risoe
Date: March 13, 2010
An (n times m) pixel PSD monitor taking phase into account. As the i:th ray hits a pixel (j,k) in the monitor the intensity in that pixel will be updated as a complex sum, i.e. <math>P_i = P_{i-1} + p_i exp{-∖phi_i}</math>.
By setting ratio<1 the effective pixel area becomes a fraction of the ideal (which is to divide the xwidth and yheight intervals into nx and ny abutting subintervals). This reduces the monitor effective area by ratioˆ2. If the centering flag is set - the monitor will treat all rays as if they hit a pixel center. This behaves as if ratio -> 0, but at no cost in statistics.
Example: PSD_monitor_coh(xwidth=0.1, yheight=0.1, nx=90, ny=90, filename=”Output.psd”)
Parameters in boldface are required; the others are optional.
|
Name |
Unit |
Description |
Default |
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nx |
|
Number of pixel columns. |
90 |
|
ny |
|
Number of pixel rows. |
90 |
|
filename |
m |
Name of file in which to store the detector images - the suffixes .abs and .arg will be added. |
0 |
|
restore_xray |
|
If set, the monitor does not influence the xray state. |
0 |
|
xwidth |
m |
Width of detector. |
0.05 |
|
yheight |
m |
Height of detector. |
0.05 |
|
ratio |
|
ratio between pixel area and effective pixel area. |
1 |
|
centering |
|
Treat all rays as if they hit the center of the pixel. |
1 |
|
nowritefile |
1 |
If set, monitor will skip writing to disk |
0 |
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Component source code found in file PSD_monitor_coh.comp.
The component PSD_monitor_coh closely resembles its parent the 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 (filename.abs) represents the coherent intensity and the other (filename.arg) the phase of the collected beam.
The first output file (.abs) from 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, filename.abs, and can be read e.g. by the tool mxplot, see the system manual. Likewise, the second output file (.arg) contains the integrated phases, and are written to the file filename.arg