Terry, Arijit, Sheila, Daneil
We started by using the scanning OPO to align the transmitted red beam through the two apertures on HAM6 (we mechanically moved ZM1 in yaw but not pitch) to the temporary DC diode we have installed in homodyne path. We scanned the OPO and saw that our seed beam wasn't well aligned to the OPO. We adjusted pitch on the 1064 collimator, and a small yaw adjustment. We hadjusted the TEC temperature to roughly align the red and green resonances (for the current crystal position). Daniel helped us get the OPO locking and we were able to see the amplification and deamplification of our seed beam. We didn't try to optimize the temperature or crystal position yet. We are not scanning the seed phase but the ambient excitation is large enough that it is scanning very quickly on its own (purge air is rather high and the table is locked).
With this fairly bright red beam generated by the squeezer we removed the septum window protector and looked for a beam returning from HAM5, but see nothing. Daniel and Arjiti added excitations SRM, but we still didn't see anything, so we decided to leave excitations running overnight on SRM and ZM2 and look in the morning at AS QPDs to see if the beam hits them. We have left the LVEA in laser hazard for this reason, and left the two soft covers with a small opening for the green beam to reach SQZT6.
If we see nothing overnight we will try to taking a look through viewpoints on HAM5 tomorrow.
HAM5 HEPI and ISI were tripped for the first few hours of this test. I have just untripped them as well as the OMs at 21:12 UTC. The good news is that the OPO has stayed locked on the mode which is resonant for 1064 for the last few hours.
There were a couple of times overnight when there were small flashes on AS_C (only about 30 uW into HAM6 above the dark noise of AS_C). One was at 11:47:25 March 21st, another at 6:59:11.
For both of these times ZM2 pitch opticalign output (unclaibrated) was at -3000 counts, while SRM pitch opticalign output was near 5500 counts. The yaw values were inconsistent between the times.
When we get back to laser safe this afternoon we can align ZM2 and SRM pitch to these values and search for a beam in HAM6, possibly with yaw excitations on.
The attached screenshot shows the alignment of SRM, OM1 and OM2 from February when DRMI and the OMC were locked after the X arm peak (40463). Compared to this alignment, I have change SRM pitch by +1000 uarad to reproduce the alignment that gave us a small flash on AS_C overnight. (SRM pitch is currently at 2933, SR2+SR3 have also changed since February, I am not sure why).