Ushiba, K.Tanaka, Hirose

We locked the feedback loop from ASWFS to DIFF_ETMY and BS. When the control was turned on, the IRX transmission power was slightly better and the reflection power was lower. However, it created a difference in the transmission power of IRX and IRY. 

Measured sensing matrix.
(file: /users/Commissioning/data/ASC/2023/PRFPMI/Sensmat/230329/{BS,EXEY_DIFF}_{PIT,YAW}_ASWFS{,_afterphasing}.xml)
-> The signal was larger on RF17 for DIFF and RF28 for BS. We confirmed that this is as shown in Michimura-san's simulation. After phasing, we inserted from the sensing matrix to the input matrix.

Adjusted phasing of WFSs.
The demodulation phases at 17 MHz and 28 MHz for each degree of freedom were calculated from the I-phase and Q-phase signals of the measurement results. The demodulation phase of PIT and YAW were averaged with the demodulation phase of PIT and YAW. We did phasing by adding the phase to the existing demodulation phases of segments 1-4 at 17 MHz and 28 MHz so that 17Q and 28Q were maximized for each degree of freedom from that average.

Set ASC of "DIFF_ETMY" and "BS" at "DHARD" filter and "MICH" filter. (Fig1)

• ASWFS->BS: AS_QPD1_RF17_Q->MICH->BS
• ASWFS->ETMY and ETMX: AS_QPD1_RF28_Q->DHARD_B->DHARD->ETMY and ETMX

Tried to lock ASC.

• In "SET_ETM_WFS_OFFSET" status of "ASC_LOCK" guardian, before testing the ASC, the average of the error signal with a negative value is inserted at the offset of the error signal to cancel the error signal. This is to temporarily stop the abrupt change in alignment when the ASC is turned on, and to test to ensure if the control does not oscillate. In this case, we did that and the control held, and it also held when the inserted offset was removed.
• When the control was turned on, the IRX transmission power was slightly better. When the transmission power was off, it was roughly 100. When all degrees of freedom were turned on, it went up to about 115. The reflection power was lower. REFL signal(K1:LSC-REFL_PDA1_DC_OUTPUT) was about 8 when it was OFF, but has dropped to 2. It also got darker looking at the REFL camera, AS also has a clear 1st order mode beam cross section when ADS and BPC control are on, but when WFS is added, beam cross section of AS also got a little darker. This is a good trend.(Fig3)
• However, adding the WFS control created a difference in the transmission power of IRX and IRY. We do not know why.(Fig3)
• We set the gain roughly with the UGF around 0.1Hz and DHARD>BS>CHARD, but not sure about the specific UGF yet.
• We tested ASC with ADS on for IMMT2 and PR2. I don't know the specific UGF of ADS, but it seems slower than WFS. So we set 10 times for gain in (INPUT of) ADS. This has not yet been implemented in guardian.(Fig3)

Modified some of the contents in "ASC_LOCK" guardian.(Fig3:Current ASC_LOCK Guardian.)

• The statuses "DOWN", "ETM_BS_WFS_ENGAGED" and "ENGAGE_ETM_BS_WFS" in "ASC_LOCKED" guardian have been changed from COMMON only to include DIFF and BS control.
• The status of "SET_ETM_WFS_OFFSET" was changed from COMMON only to include control of DIFF and BS. But not sure if we'll keep the status here.