diff --git a/Energy-Drift-Correction.-.md b/Energy-Drift-Correction.-.md index 8707cad..8e8f3e2 100644 --- a/Energy-Drift-Correction.-.md +++ b/Energy-Drift-Correction.-.md @@ -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. \ No newline at end of file +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