We tried to perform the initial alignment OMC.
By changing the initial REFL HWP 125 to 140, we completed the increasing the laser power, but OMC cannot be locked.
Ushiba-san commented that maybe the power of pzt OMC was off, so we cannot change the OMC length.
We will check it when we enter the mine next time.
[Hirose, Ushiba]
We turned on OMC PZT driver and confirmed OMC length can be scaned by PZT offsets (fig1).
Since +/- 18 V for the circuit is provided by the external power supply, we set the voltage of +/- 18 V and the current limit of +/- 0.5 A.
Note:
During the recovery work of OMC PZT driver, we found that DC 100V power supply is ON (fig2) though the main power is turned off.
I don't know te detail of the power supply but it is likely that DC 100V was automatically recovered after the unexpected blackout.
If this situation is not good for PZT driver, we need to consider how to avoid it.
After recovery of the OMC PZT driver, OMC can be successfuly locked and initial alignment can be done (fig1)
