I observed WFSf3 signals on PRXARM at the first time. Although there is room for consideration, the signal of PR3 appeared to be the largest.(FIG10)
Detail
- First, I installed a DC centering loop that was not RF90. Since the INPUTMatrix for the DC part of WFSf3 has not yet been implemented on the MEDM screen, I used the caget command to input it. (FIG1) I also confirmed that the DC signal was input to the INPUT of the centering loop. After this, I measured the sensing matrix with a slightly slower centering loop. We will have to discuss in the future whether we should change a faster centering loop.
- Each mirror was excited at 1.3 Hz in the PIT direction, and IMMT1 was excited at 0.5 Hz.
(FIG2: ITMX, FIG3: ETMX, FIG4: PR3, FIG5: PR2, FIG6: PRM, FIG7: IMMT1, FIG8: IMMT2)
First, I observed the WFS detection signal using the PMPM beat signal when exciting the mirror. (FIG9:PR3) - I summarized these results in a plot of the demodulation phase.(FIG10)Both QPD1 and QPD2 clearly show PR3. However, it is not perpendicular to ITMX. Also, WFSf3 shows ETMX. Normally, the difference between PRC and the incident axis should be detected, but this is a mystery. It is urgent to consider the target of WFSf3.
- I also summarized the results of klog30337 in a demodulation phase plot (FIG11). Compared to FIG10, there are some parts where PR3 is detected in the RF17 and RF45 signals, but the ARM signal can be seen depending on the QPD gouyphase. This is a big difference from WFSf3. And the signal size is much larger than WFSf3.
- Finally, I measured the sensing matrix of the PR3 using RF90 centering. However, on the spectrum, it looks the same. (FIG12) It may be better to actually install the control and check if it is applied as an offset.
Future Plan
I'm very happy that I was able to observe the WFSf3 signal this time. However, there is still much room for consideration.
- Investigate the target of the WFSf3 optical axis ---> examine the coherence with TRANS power, etc.
- DCcentering or RF90 centering loop --> install control and check if an offset appears.
- I would like to try WFSf3 in PRFPMI.
