MicroSpectro/Pixelator
Private
Public Access
11
1
Wiki

Update Energy-Drift-Correction

watts
2026-03-16 17:06:01 +01:00
parent 9a64611dcc
commit 59abd70690
1 changed files with 17 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Energy-Drift-Correction.-.md
+17 -1
@@ -50,4 +50,20 @@ Note that adjusting the interferometer mirrors to optimise the signal intensity
# Applying a Feedback Drift Correction
The zCorrectMatrix values [X,Y] are applied by Orocos in the J/K->X/Y coordinate transform. This means that all of the bad effects of a virtual drift are neutralised at the Orocos level. The only negative effect would be a (typically insignificant) shift in the coordinate system when the interferometer is reset at a significantly different photon energy from the previous reset. This occurs because the correction is calculated based on a reference point that is chosen as the position of the last "reset interferometer". Since an interferometer reset also defines a new coordinate system based on a reading of the position encoders on the coarse stages (with the fine piezo stage in a relaxed, 0 mV position) (and there will also be a coordinate shift due to previous positions being incorrect via accumulated errors in counting fringes), there is typically going to be a shift in the coordinate system anyway that will be more significant than the zCorrectMatrix shift.
The zCorrectMatrix values [X,Y] are applied by Orocos to the feedback system, meaning that all of the bad effects of a virtual drift can be neutralised at the Orocos level. The only negative effect would be a shift in the coordinate system when the interferometer is reset at a significantly different photon energy from the previous reset. This occurs because the correction is calculated based on a reference point that is chosen as the position of the last "reset interferometer". Since an interferometer reset also defines a new coordinate system based on a reading of the position encoders on the coarse stages (with the fine piezo stage in a relaxed, 0 mV position) (and there will also be a coordinate shift due to previous positions being incorrect via accumulated errors in counting fringes), there is typically going to be a shift in the coordinate system anyway that will be more significant than the zCorrectMatrix shift.
To access the feedback drift correction parameters, first connect to the Orocos instance:
```
telnet localhost 50001
```
To see the current drift correction parameters, enter the following command to see the pair of values:
```
Deployer [S]> Sensor1.zCorrectMatrix
```
The first (zero entry) value is for the X-axis and the second (entry 1) value is for the Y-axis. Values can be set by addressing each entry in the array, e.g.:
```
Deployer [S]> Sensor1.zCorrectMatrix[0] = 0.0
```
The parameters are in terms of microns of lateral adjustment per micron of Z-axis movement of the zone plate stage. Values should therefore be small, e.g. -0.005<x<0.005, but there is no software restriction.
The values at PolLux were recently set to [-0.0027,0.001]