[Kokeyama, Yasui, Ushiba with help of Tomaru, Yokozawa]

Abstract:
We succeeded in flashing the X arm with IR beam.

Detail:
In the moring, IMMT1, IMMT2, and PR2 were moved back to the position just after yesterday work with respect to the OpLev signals.
Then, we checked IR forward beam position at PR3 and backward beam position at the gate valve between MCF and IFI, and no problem.
After this work, Yokozawa-san centered OpLev QPDs of IMMT2 and PR2.
Also, Tomaru-san opened the gate valves between IXA/EXA chambers and X-arm.

After chacking the beam position, we went to X-end and changed the TMS-X_IR_PDA1 gain (from 0 dB to 60 dB, if I remember correctly).
Then, we found Green flash (and even single shot from PR3) was disappeared, which can be due to opening the gate valves.

So, we recoverred GreenX flashing.
First, PR3 was tweeked and found the GreenX beam at X-end (excited from K1:VIS-PR3_TM_SET_{P,Y}_EXC).
Then, ITMX and ETMX were tweeked (excited from K1:VIS_{ITMX,ETMX}_TM_SET_P_OUTPUT) to find GreenX flash and found.
Since observed flash was not TEM00 mode, we tweeked ITMX and ETMX manually while seeing the transmitted beam mode, and found TEM00.
After finding TEM00 of GreenX, IMMT2 and PR2 were tweeked in the same method in klog19363, and found IR flash at X-end (see fig1).

After  finding IR flash, we went to X-end again and did several work:
Centering IR beam to PD and camera by moving steering mirrors' angle (but already almost centered before moving steering mirror).
Removed high reflectivity mirror in the path of CCD camera, which is probably for reducing beam power during PRFPMI configuration.

Figure2 shows the IR camera on TMS-X optical tabe when X-arm was flashing.

After the work, we closed both gate valves, which we opened today.

Note:
After opening the gate valve, good OpLev values of ITMX, ETMX, and PR3 were as follows.
PR3: (P,Y)=(-82.0,81.0) -> (-108.3,118.0)
ITMX: (P,Y)=(40.9,-17.2) -> (25.0,47.0)
ETMX: (P,Y)=(33.3,-7.9) -> (35.0,-36.0)