focus
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Focus Sequence
Use Run Focus in the AzCam window to make a focus exposure sequence.
A new instrument command has been added to move the focus actuators to specific LVDT values. Type, for example,
instrument.SetActuators(0.874,0.825,0.795)
to move the actuators (A,B,C) to the positions indicated.
Misc Focus Info
- The image header has a line like: FOCUSVAL= '*0.756*0.795*0.815' / Focus
- These are LVDT (encoder) values corresponding to '*LVDT_A*LVDT_B*LVDT_C'
- One focus actuator step is 2.645 microns, which corresponds to -0.0005 LVDT units. So the conversion is (-1322.5 um/LVDT unit).
- Note the zero point for the LVDT scale is arbitrary and only relative motion should be considered.So for example, 0.756 above for LVDT_A is a position of (0.754 * -1322.5) = -997.2 microns.
- Note the direction sign is reversed between actuator movement and the LVDT readout.
focus.1479531387.txt.gz ยท Last modified: 2016/11/18 21:56 by mike
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