Tanaka-kun's report on April 30 2024 and May 1st was very similar to the present situation. Do we forget something to do about interlock???

Accroding to a mannual that was delivered from Mio-sensei today (this is the first time for me to see the mannual for FBL), FBL amplifier has a intelock connector that has 4 pins. 1-2 and 3-4 should be connected to operate FBL.

Date: 2025/09/29

Member: Misato Onishi, Keisuke Sakanoue

We performed our usual WSK calibration at UToyama.

The results look no problem.

Results

Comparison with Previous Results

Comparing with previous results, no significant issues were found.
Attached graph is the result summary including the latest measured data.

According to Mio-sensei, the most fragile part is the ADC/DAC board in the Amplifier. This might explain the strange data of temperature and so on.

We have no way to repair ADC/DAC at present.  

[miyakawa, uchiyama, miyoki(remote)]

[Abstract]

The broken? FBL was replaced with a spare one. However, we could not operate it. At present, we suspected that the control software had bugs or that the spare FBL was also broken.

[What we did]

• The old FBL was removed from the 19 inch rack, and set the spare FBL in the same 19 inch rack.
• Hoses to the chilleres, and optical fibers to the master laser optics and output optics on the table were connected to the spare FBL. Very simple connections. The chiller was on.
• Proceeded the laser operation according to Nakano-kun's manual. However, we encountered the following troubles,
  • When turning on the master laser and applying the current as in mannual, we got 13mW values as the input laser power for the amplifier in the software GUI. This was the same to the broken ? FBL case. In addition, actually, ~ 1W laser power can be detected at the out put of the FBL amplifier. This was also the same stituation to the broke FBL case. 
  • Before enabling the amplifier,  3C !! temperature was displayed in the NuAMP_RACK FBL controller software GUI. This was also the same situation to the broken FBL. This value should be 23C or so, according to the Nakano-kun's mannual. 
  • After enabling the amplifier, 13mW became 26mW and temperature became ove 50C!! However, no warning was displayed in the GUI. This was also the same situation to the broken FBL.
  • We increased current gradually. However, no changes in the FBL output power. This was also the same situation to the broken FBL.
• We suspected that the mechanical interlock in the amplifier. So we mechanically shorted the interlock terminals to kill the interlock. However, the situation was the same.
• We suspected USB outputs on the PC side. So we changed the USB port. However, no FBL output.
• We suspected that windows PC bugs. So we rebooted the windos PC (Windows10) and tried. However, no FBL out put.
• We suspected that some initial data files that were used by the software. However, we could not find such data, except for the calibration data of the FBL power.
• Although we wanted to reinstall the control software, we could not find such installation devices near the windows PC.
• We checked the directry  where NuAMP_RACK FBL controller software was installed. We found another software for the FBL control. We used this aftware. We found that this software apperacne was alsmost same to the previous one, except for warning messages as follows,
  • Seed signal Too Low, master Fault, even 13mW was obtained.
  • Temperature too high, even 3C was displayed in GUI.
  • Back reflection too high. We could not understand this message.

We are now asking Mio-sensei any ideas about these situations and also asked him and Nakano-kun whetehr we can obtain the software installer.

Anyway, the displayed temperature of over 50C dgrees was strange and it could enable the software interlock to the amplifier. Or, both FBL were broken.

I checked the past data as Fig.1, especially around the July 30th when Kamchatka earthquakes happened because Type-As were tripped and forcely misaligned for one day, and because IFO was set down on purpose for 1 week to avoid the after shocks. Fig.1 shows,

• date of zero is the earthquake event.
• During one day after the earthquakes, ALS-X/Y_PNC_SERVO_IN1_DQ should show the power from the PSL room only because the ITMXY were tripped and misaligned. PNC-Y side clearly showed power fluctuation! While, no power fluctuation in PNC-X side.
• After the ITMXY recovery to the aligne mode, both showed interference fringes. PNC-X showed constant fringe width, while PNC-Y showed fringe width fluctuation as reported Ushiba-kun. The same kind of fringe fluctuation can be seen before the earthquakes during IFO locking.

Consequently, the reported fringe width fluctuation did exist around July 30th, 2025.

As the next investigation, I traced back when this PNC-Y fringe fluctuation started. Fig. 2 shows the data around August 30, 2024, that was just after the start of the IFO recovery. The PNC-Y fringe fluctuation seemed to be much smaller than now. However, PNC-Y fringe fluctuations can be recognized around September 30, 2024! as Fig.3.

So, the PNC-Y fringe fluctuation seemed to exist for 1 year. We just found such phenomena, that were triggered by the recent many trouble shootings.

The larger fluctuation of ALS-Y(and X?)_LASER_TEMP_SERVO_OUT16 seemed to continue as Fig.1 and 2. Actually, PSL-PMC_ZPT_HV_OUT_DQ also seems to be a little bit noisier than the stable state as Fig.4. I checked the same data in July and June. The past data was comparable with the noisy level which is reported in this post. So, the fluctuation itself seems not to be problem 

IMC trans is getting worse as in Fig.3. Fig.4 also shows the relation between the slight PMC trans reduction around -2 days and noisy PSL-PMC_ZPT_HV_OUT_DQ.

IMC and PMC were unlocked 6 times for 40 minutes as Fig.1 and 2. One or two of them seemed to be related with earthquakes. 

Fig3 and 4 show the close up one of lock loss timings. PMC was unlocked 4 times, while IMC was unlocked 11 times or so. Especially, Fig.4 shows the glowing up noise in PSL-PMC_MIXER_MON_OUT_DQ.

Fig5 an 6 show the close up with seismic noise enhancement. Fig.6 shows the glowing "down" noise in PSL-PMC_MIXER_MON_OUT_DQ.

Fig.7 and 8 show the noisey timing including Fig3,4,5,6. Fig.8 shows glowing "up and down" noise in PSL-PMC_MIXER_MON_OUT_DQ.

On the other hand, IMC trans decreased after the big shock due to earthquake about 1 day ago. I don't know weather the IMC alignment changes were related with the IMC successive unlocks or not (Fig.9) even though the IMC-SERVO_OUT2_OUTPUT values (offset in other words) were almost constatnt. 

Fig10 and 11 show PLLX/Y. In the recent half day, the ALS-Y_LASER_TEMP_SERVO_OUT16 seemed to fluctuate more compared with the past, while ALS-X seemed to be same woth the past. So, is it better to adjust PLLY?

Takahashi-san reported that the temperature at IYV decreased too much, then F0 GAS position became too low. I increased the heater power again in IYV by 600W. I will reduce it to 300W tomorrow.

Also, the temperature at IXV was decreasing too much. However, I could not increase the heater power because of network discinnection. I will check tomorrow.

More two lock losses around -7 hours. They had no correlation to the seismic noise. However, They are quickly recovered and no continuous lock losses happened. In addition, the IMC trans seemed to decrease and IMC trans power increased at the latest lock loss. So these lock losses were caused not by known crazy noise in the laser but other noises, perhaps.

Operators: Kokeyama, Nakagaki

Shift time: 09-17 JST

Check Items:
VAC: No issues were found.
CRY cooler: No issues were found.
Compressor: No issues were found.
Temp check: (at 10:00) FIELD_IYA changed by +0.5°C and COOLER_BS changed by +0.4°C. Reported to Miyoki-san and Hayakawa-san.
                   (at 16:00) No issues were found.
VIS GAS filter output check: (at 10:00 and 16:00) ITMY F0 over -25,000 counts. Reported to R.Takahashi-san.

IFO state (JST):
09:00 Start of shift: STANDBY
17:00 End of shift: STANDBY

Operators: Kokeyama, Nakagaki

Shift time: 09-17 JST

Power Outage at Kashiwa.

Check Items:
VAC: No issues were found.
CRY cooler: No issues were found.
Compressor: Not checked due to the power outage at Kashiwa and not accessible to the image.
Temp check: The temperature in IYA changed by -0.40°C at 10:00. Reported to Miyoki-san and Hayakawa-san.
VIS GAS filter output check:  Not checked due to the power outage at Kashiwa and not accessible to the image.

IFO state (JST):
09:00 Start of shift: STANDBY
17:00 End of shift: STANDBY

Only one lock loss because of an earthquake near the site for the last 1 day and 16 hours as in Fig.1 and 2. Aftre relock, the IMC trans decreased a little bit.

You can see slight enhancement arout -21 hours in PSL-PMC_PZT_HV_MON_OUT_DQ. Fig.3 shows the close up around the enhancement in PSL-PMC_PZT_HV_MON_OUT_DQ. This enhancement is because of the very long oscillation (~ 5 minutes in this case). It had relation to PSL-PMC_HEATER_OUT16. So, some instabilities in the temperature control time scale could happen.

I decreased the current as Fig.1.

Steady reduction of EY IM temperature. IX IM temperature reached almost equilibrium temperature.

No IMC unlock during 1 day and 6 hours as Fig.1 and 2. However, the PSL-OMC_PZT_HV_MON_OUT_DQ became noisy around -6 ~ -12 hours.

Operator name: Yuzurihara, Takahashi

Shift time: 09-17 JST

Check Items:
VAC: No issues were found.
CRY cooler: No issues were found.
Compressor: No issues were found.
Temp check: No issues were found at 10:00. The temperature in IYA changed by -0.40°C at 16:00.
VIS GAS filter output check:  No issues were found.

IFO state (JST):
09:00 Start of shift: STANDBY
17:00 End of shift: STANDBY

[Kimura, Yasui, Nakagaki and Sawada]

 H. Sawada-san reported via Yasui-san that water is leaking from the heat exchanger in the central machinery room's cooling water circulation system for the cryo-cooles.
Inspection of the leak location failed to identify whether it originated from the primary or secondary side of the heat exchanger.
Therefore, the monitor camera position was adjusted to enable monitoring of the secondary side cooling water level.
 (See attached photo)
 The black sphere inside the glass water level tube should be positioned within the green area to indicate normal operation.
The yellow area indicates a cautionary state.
When in the yellow area, Slack will issue an alarm for a drop in secondary-side cooling water level.

I shut down the Pastavi server today to prepare for the Power outage at the Kashiwa campus. Hopefully, it will come back online next week. 

Abstract:

IFO lock acquisition is now not stable maybe due to the degradation of PNCY performance.

Detail:

After initial alignment, I tried to lock IFO but continuously failed to handover ALS signals to IR signals.
So, I checked ALS related signals and found that the fringe size of PNCY was drastically reduced, which causes the degradation of PNCY performance.

Figure 1 and 2 shows the PNC error signals yesterday and today, respectively.
The fringe size is roughly 1/4 now compared to that yesterday.

The degradation seems to start from this morning and gradually proceeded during the initial alignment procedure.
Figure 3 shows the time trend of PNCY error signals.
It is hard to see the graph, the fringe size seems large before ITMY misalignment.
In addtion, DC output from the PD was gradually reduced when ITMY was misaligned, which implies that the light in the reference path might changed.

To recover the IFO, it is necessary to investigate what happens maybe by checking the optics on POS table.

Fig1,2 show IMC/PMC signals on Today (Master current = 1.2A) and Fig.3, 4 show those on Sept 14 (master current = 1.55A) during lock acquisition of IMC.

Almost same RMS values can be seen among them. So no significant changes in the frequency noise is expected. The reduction of RMS in PSL-PMC_MIXER_MON_OUT_DQ is just because of IMC lock.

Please note that the noise eater was on on Sept 14th, however, off today.

I also checked the IMC/PMC signals among today(after noise eater off) and yesterday (before noise eater off) (Fig.1,2). The white dotted lines in Fig.2 shows the enhanced RMS level reported in klog#35148.

Amazingly, the RMS of PSL-PMC_MIXER_MON_OUT_DQ today is smaller than yesterday, and the reported RMS enhancement in today's data is just comparable with the RMS yesterday.

So, the reported RMS enhancement today is not so serious ?

Fig.1,3 shows the IMC/PMC situation. Although I reported no unstability in IMC, PSL-PMC_MIXER_MON_OUT_DQ shows a slight noise rms increase sometimes as in Fig.4. It is better to check some error signals in IMC control.

This noise increase seems to be the rms ehnacement, not fast gliches as in Fig.2