In short - I've added a bit to the ALS_DIFF node in the FIND_IR and SAVE_OFFSET states. The goal was to have it handle the case that was seen the other night where it goes to an offset and there is the smallest bit of light above the noise, but it's still be low threshold and won't fine tune. Just lowering the threshold won't work since this noise seems to vary a bit, so I added in a few other checks.
I didn't fully test this since we've already been down for a few hours from an earthquake and I would have had to restart locking. If this causes any problems, please give me a call or revert ALS_DIFF.py in SVN. I already have a copy saved.
I had a chance to test it out a bit more thoroughly after a lock loss around 130 PT. This time I forced it into a situation where it would overshoot resonance and have a very small amount of light in the signal. It then jumped back and got close enough for the fine tuning threshold to move the node into the next state to fine tune.
This situation has been the most frequent cause of the node not finding IR resonance this year, so hopefully this helps reduce assistance required requests. Next steps for this node are to make a "long search" state that will search through the full range for good buildups, and fix the times that it will fine tune indefinitely, circling around the correct value. This latter issue should just be a minor tuning change, but it's challenging to test.
