R. Short, J. Kissel

Following investigations into the 102Hz feature that has been showing up for the past few weeks (see alogs 72064 and 72108 for context), it was decided to try a lock acquisition with the calibrations lines off until much later in the locking sequence. What this means in more specific terms is as follows:

• ISC_LOCK has a new state called TURN_ON_CALIBRATION_LINES (index=562) which will happen in the nominal locking sequence between LOWNOISE_LENGTH_CONTROL and INCREASE_DARM_OFFSET. This state sets the gains for all three ETMX stages' calibration lines according to lscparams (fixed the varying line heights in alog 71970).
• The PREP_FOR_LOCKING state now only turns off the lines in the main method and does not turn them back on.
• The TRANSITION_FROM_ETMX state used to turn the lines off. This is now no longer needed.
• The NOMINAL_LOW_NOISE state no longer makes sure the lines are on or turns them on at all.
• The NLN_CAL_MEAS state no longer saves the current line gains before turning the lines off to reapply them when they're turned back on. The state simply sets the gains to zero, then sets them back to their defined value from lscparams when moving back to NOMINAL_LOW_NOISE.

For each of these points where the calibration lines are turned off or on, the code structure is now consistent. Each time "the lines are turned on/off," the cal lines for ETMX stages L1, L2, and L3 (CLK, SIN, and COS), PCal X, PCal Y, and DARMOSC are all toggled.

The OMC and SUSETMX SAFE SDF tables have been updated appropriately (screenshots attached).

These changes were implemented on August 14th around 22:45 UTC, are committed to svn, and ISC_LOCK has been loaded.