Here are the transfer functions of the individual components along with the OLTF.

RXA: please spend some time trying to make the plot more useful: grid lines, distinguishable colors, zoom into important range, some text descriptions of each trace, comments on differences between theory and reality, etc., etc., etc

While modelling the system, I had no way of knowing the gain of each individual component. The individual transfer function of the PDH box and overall open loop is known, so I combined the Cavity, PZT, Low Pass filter, and Photodiode into one block, and fitted its overall gain to match with the overall OLTF of the system. 

Using this setup, with the pole values taken from Gautam’s thesis, and the fitted PDH zpk values; I was able to get the OLTF of the model to agree with the OLTF experimentally taken. I now use the model as a base for the setup, to test controller designs, impulse response, and stability margins. There is some deviation from the experimental value (~10dB in magnitude in the low frequency range, ~20 deg phase). 

We can see that at lower frequencies, the PDH box influences the transfer function while at higher frequencies the other components contribute. This is a good sign as we primarily want to increase the stability and performance of the system in the 10Hz to 20kHz range (Which is where the AUX laser noise is suspected to dominate in the ALS beat note) and this can be easily adjusted by changing the PDH box parameters. 

 I tried to simulate this block using the SR560, I tested with both a single and double pole at 30kHz. The 2-pole setup seemed to be the closest to the combined cavity, pzt, photodiode, low pass filter and summer combo (plant).  

With two poles at 30kHz and the fitted PDH controller implemented on the Moku: Go, I took an OLTF, and it was deviating ~20 dB from the model (in hindsight, I could've increased the gain in sr560 (but I dismantled the setup to use the SR560 to take OLTF at with digital controller at XEND) will take another reading if I get time, but still the phase is way off).  

I have moved onto implementing the digital PDH box on the actual system, I have not been able to design an optimal controller, but using the fitted values, and increasing gain on the Moku, I was able to achieve similar (not necessarily better in terms of open loop characteristics as that of the original PDH box. I will get some more data and post the comparisons of OLTFs and noises when locked.
 

ETMX freeswing test will start at 1:00 AM.

To cancel it run:

I modified freeSwing.py so that it doesn't turn off the filter banks in the ETMX suspension screen as to not change the alignment before the kick.

Dean made the OMC cables for the BHD Platform. They are going through the C&B process.

From left to right: QPD cable, PZT cable with Picomotor etc, DCPD cables

Since we removed the Acromag chassie modbus service could not be started so the soft Epics were not availble and the watchdog was not working essentially.

I made a temporary fix by commenting out the Acromag related comands in /cvs/cds/caltech/target/c1auxex/ETMXaux.cmd (a backup was created named ETMXaux.bak.cmd). More specifically, this block was commented out:

This allowed the modbus to start. Once the chassie is back this bloc will need to be restored with possible changes if we decide to add/remove Acromag units.

Unfortunately, software watchdog is still not functional since the logic turns off the enable switch on the coil driver using an Acromag BO that is not there. I'm still trying to figure out how to turn off the MEDM screen coil driver output using the Epics logic.

The new laptop for the Beam Profiler is ready for usage.

From the last meeting, we came to the idea of having 2 laptops that are designated for the beam profiler specifically. We now one laptop over at WestBridge, and one here at 40m. This makes it easier to travel with just the Beam Profiler heads, rather than carrying the Profiler heads + laptop. This machine has been named Stella by ChatGPT. Feel free to use it! (Only runs Windows 10)

Too many cavity poles! It should be just a single pole. Please show us your OLG Bode plot on the same plot as each of the individual pieces of the loop, so we can see what contributes to the TF.

Wanted to see if digital filter on the Moku:Go can be changed without breaking lock. Loading different filter files broke lock. Tried to set two identical filters and have an output matrix to switch between them, but the Moku:Go lacks the capability for that, so I switched to a Moku:Pro, which lets me configure an output matrix in multi instrument mode. Changing the output matrix in multi instrument mode on the Moku:Pro does not seem to break lock, but the transmission kept jumping erratically, I did not know if the low transmission was causing the instability.Maximum transmission was around ~0.6 when locked.

Yuta let me align the arm cavity, was able to get transmission upto ~0.9 while locking with the Moku:Pro. Lock held for aorund 5-7 seconds before breaking, it was not enough time to test if changing the output matrix is breaking lock. I was able to keep it locked to a higer mode, with ~0.2 transmission (not ideal) and changing the output matrix does not cause any erratic changes in transmission (dont know if this will translate to TEM00 mode). Will try again tomorrow to change output matrix while stably locked to TEM00. I realigned the arm cavity to it's original state and got main laser transmission back to ~0.9. I also noticed that it's easier to lock when input gain is attenuated (~ -5dB), the plan is to lock with a low gain filter, and switch to a more agrressive filter to hold lock stably.

Locked with Moku:Go

Locked with Moku:Pro

I borrorwed a visual fault locator for fiber cables from QIL with permission from Yehonathan.

I am going to use this in the 40m to construct the in-air mode-matching telescope for the OMCs.

I found that the MC transmission was low (~13000. Usually it's ~13500) in the morning.
This was due to the low transmission of PMC (~0.675. Usually it's ~0.685), so I restored the PMC alignment using the two steering mirrors before the input mirror.
The transmission of MC and PMC was restored to ~13300 and ~0.687.

[Yuta, Hiroki]

We conducted the followings for the PRMI experiment on Jul. 18:

• Leaned alignment tips?
• Measured the OLTFs for PRCL (UGF~220Hz) and MICH (UGF~50Hz)
• Data for noise budget: gpstime 1373763480 - 1373763560
• Measured the sensing matrix 
• Succeeded in locking for ~20 min. in the end

Details

OLTFs for MICH and PRCL:
We measured the OLTFs for MICH and PRCL (Atatchment 1 and 2).
The data for MICH is saved as measurements/LSC/MICH/MICH_OLTF_20230718.txt
(Sorry for forgetting to save the data for PRCL...)

• PRCL UGF ~ 220 Hz
• MICH UGF ~ 50 Hz

Data for noise budget : 
 1373763480 - 1373763560 (controlled by the OLTFs above)

Tips for stable lock
We succeeded in locking the PRMI for ~20min with the following conditions:

• MICH: AS55_Q, Power normarization with POPDC=1; gain=800; Out MTRX BS=0.5, PRM=-0.33
• PRCL: REFL11_I, No normarization; gain=-0.01; Out MTRX PRM=1  

For the stabler lock, the alignment of MI seems essential.
Before locking the PRMI, you should misalign PRM, lock MI and carefully minimized the ASDC with monitoring the video.

Sensing Matrix 
We measured the sensing matrix using scripts/CAL/SensingMatrix/ReadSensMat.ipynb :

Sensing matrix with the following demodulation phases (counts/m)
{'AS55': 2.0999999046325684, 'REFL55': 76.0199966430664, 'REFL11': 32.638, 'REFL165': 92.23478110797188}
Sensors       MICH @211.1 Hz           PRCL @313.31 Hz           
AS55_I        (+4.44+/-2.93)e+08 [90]    (+1.69+/-0.37)e+10 [0]    
AS55_Q        (+9.89+/-1.00)e+09 [90]    (-3.77+/-0.50)e+09 [0]    
REFL55_I      (-6.12+/-2.24)e+11 [90]    (+3.70+/-0.37)e+13 [0]    
REFL55_Q      (+1.46+/-0.53)e+11 [90]    (-8.89+/-0.86)e+12 [0]    
REFL11_I      (-1.43+/-0.53)e+10 [90]    (+9.13+/-0.86)e+11 [0]    
REFL11_Q      (-7.73+/-3.71)e+08 [90]    (+5.13+/-0.50)e+10 [0]    
REFL165_I     (-3.73+/-0.49)e+09 [90]    (+6.20+/-0.60)e+10 [0]    
REFL165_Q     (-1.38+/-0.10)e+09 [90]    (-2.24+/-0.17)e+10 [0]    

We decided to verify the PWM accuracy by adjusting the oscilloscope to fit a hundred cycles of the signal and measuring the mean voltage - the variation is linear as expected, although it does diverge at the extremeties as noted earlier.

Additionally, I compared the experimental data in the previous plots with a simulation using the model that we constructed, and after accounting for time delays in heating the system, we see a very good agreement between the two - 

I was able to use the Moku:Go to implement a digital controller and substitute the analog pdh box to lock the green laser at x end. I took the RFPD IF OUT (the error signal) and Servo Input (Control signal) and passed them through the Moku:Go filter. The mixer of the analog box is still used. The controller implements a digital filter with the poles and zeroes fitted to that of the analog controller. Transmission was low (~ .2 - .4), but similar to that acheived with the analog controller at the time, probably due to misalignment of the cavity. Changing the filter on the fly using the Moku gui brings about a momentary dip in transmission, but immediatley rises back to normal most of the time. The smaller the change in filter parameter (eg. gain 1dB -> 1.1 dB) the shorter the dip period.

I will test out how feasible it is to switch filters on the fly and have some python scripts that will switch filters, and one to potentially take transmission/reflection data and figure out if lock is broken. Play around with gain and offsets and filter coefficients, see what happens..
 

What's the nominal AOI for the mirror and the T value at that angle in a number? We will need that later.

I took away the fiber collimator and the collimator mount from the air BHD setup [Attachment 1 (before removal), 2 (after removal)]

The removed collimator is shown in Attachment 3 and will be used for mode-matching telescope for the OMCs.
 

I removed the T&R measurement setup with permission from Radhika (Attachment 1).

I will put away the chopper used in the setup tomorrow (the location of the chopper will be written here: elog #17822).
I am going to construct the mode-matching telescope for the OMCs here.

I wrote a Python code to simulate the AUX laser stabilisation system. It takes the poles and zeroes of the individual components (cavity, pzt, summer, low pass filter, pdh controller) and combines them, and shows the stability margins and impulse responses. Now any PDH controller designed can be easily plugged into the code and the stability and perfomance of the loop can be tested.

Trying to make a tabletop simulation of the setup, using an SR560 preamplifier with a second order pole at 30kHz to model the arm cavity and other ocmponents. The Moku:Go will be the digital PDH controller, and transfer of the setup will be taken with another Moku:Pro (not enough Gos). The individial and combined OLTF of the setup is taken and compared to the similar data. 

I loaded the same digital filter into both the Moku:Pro and Moku:Go, to see if there was any difference. I used the multi instrument mode, with Digital Filter and Frequency Response analyser. To my surprise, every configuration else exactly same, the transfer function was different for both Go an Pro. I also ran the Filter on the Go, and took the frequency response using the Pro, the transfer function was identical to the Go taken internally.The Pro is giving the expected transfer function. Idk if i am missing something here.

I will be testing out the digital controller on the Xend AUX setup today, replacing the anlaogue PDH box with the Moku:Go fitted with, see if i can get a lock with the digital version, see any problems that might come up.

I've made a cleanroom assembly in solidworks to create a list of all the components we will need when making this. Sadly, the 80/20 that we have in the cage area was taken already. I can't point fingers because the lock was removed due to it being an optional emergency exit way pointed out by Caltech Safety. Here is the 3D model of what the assembly looks like. Please let me know if you have any questions. 

I have not calculated the cost yet, but I will tomorrow. 

Just realized I wrote out but failed to post this ELOG update before I left last week:

On Thursday 07/05, I simplified the transmission measurement setup since a gain reference signal was no longer needed [Attachment 1]. (This is because the reference beam previously had to hit the TRANS PD, and now this wasn’t needed).

For the s-polarization measurements, I placed a HWP after the PBS to rotate the polarization. I used another PBS to ensure that the light was being reflected and tuned the HWP angle to minimize transmission [Attachment 2].

I’ve included transmissivity plots as a function of angle of incidence, for s and p polarizations [Attachments 3, 4]. For each point, I include the result from the Moku:Go spectral peak finder and the result from performing a FFT on the time series data.

I unmounted the PR2 optic and placed it back in its original case. I’ve left it on my desk if anyone needs it [Attachment 5].

Update: we have a working "I" controller for the puck. Here is the data:

In achieving this, we had to make a few changes;

 1. In the heater circuit, the resistor is now connected to its own power supply set for 10V. This enables us to have around 50% duty cycle at equilibrium for T_ref=45C:

*This is the heater profile for the above "I" controller run
 2.  We changed the frequency of the Pulse Width Modulation (PWM) of the RaspberryPi that is used to switch the MOSFET. It is now 100Hz compared to the previous 1kHz. I observed using the oscilloscope that the PWM was delivering ~870Hz when set for 1kHz and that it also struggled to deliver accurate duty cycles, especially for low duty cycles (below 5%). The duty cycles should always be kept between 5%-95% for accurate modulation.
 3. In case we want to change the power supply voltage, the controller code can be easily adjusted by just changing the maximum voltage constant.

I borrowed two beam profilers (WindCamD and Beam'R2-DD) and a laptop from the cryo. lab in the WB.

I am going to use them for mode-matching to the OMCs in 40m for a while.

Borrowed an NPRO controller from Liyuan @ Downs B138

Model M125/6-OPN-PA
SN 359M
Manufactured March 1998

The laser illumination is back with this controller.

POWER ADJ 0: 1064nm OUTPUT 277mW / 532nm OUTPUT (right after the harmonic separator) 0.67mW
POWER ADJ +10: 1064nm OUTPUT 364mW / 532nm OUTPUT (right after the harmonic separator) 1.09mW
Inter lock connected

Y arm green was still aligned to the arm cavity. I could confirm the Y green was locked with GRTY ~0.2.
The crystal temperature was adjusted to be 43.6degC as before and this actually did reproduce the beat note between the Y end AUX laser and the PSL.

The broken controller was labeled and stored in Yarm cabinet E03.

Model 126/6 M
SN 239M
Manufactured July 1996

PRMI carrier on 1f now locks for ~1min but not more. Below is the configuration.
The configuration is the same as basically the same as 40m/17578, except for PRCL gain. Maybe the RF demodulation phases changed?

MICH
  - AS55_Q (24 dB whitening gain, C1:LSC-AS55_PHASE_R=2.1 deg)
  - C1:LSC-MICH_GAIN = 0.4 gives UGF of around 30 Hz
  - -0.33*PRM+0.5*BS
PRCL
  - REFL11_I (18 dB whitening gain,C1:LSC-REFL11_PHASE_R = 32.6 deg)
  - C1:LSC-PRCL_GAIN = -0.005 gives UGF of around 150 Hz
  - PRM

Lock stretches:
  - 1373325207-1373325231 (with MICH @ 211.1 Hz and PRCL 311.31 Hz lines on)
  - 1373328637-1373328718 (without lines)

Next:
 - Check PRM actuation
 - Measure beam spot positions on PRM, PR2, PR3 and BS (with PRX or PRY configurations to make it easier)
 - Investigate why PRG fluctuates so much
 - Sensing matrix measurement (need longer lock stretch)
 - Try PRMI 3f for PRFPMI

The LED blinking on the head is normal. We can ignore that.

It is likely that the controller is the issue. I brought the PSL AUX laser controller to the Y End, and the laser turned on / the green light was visible.

Resolution:

- Find a spare controller (West Bridge, Downs). I could not find a spare controller. There is a dead (~5mW) NPRO in a cabinet, so there should be an unused controller...where?

    - Asking Downs/Liyuan if he has a spare -> Yes he is
    - CTN has two NPRO sets. One is functional. The other is not. It was confirmed that the controller is broken and the head is alive. (cf [ELOG CTN 2619])
    - Use the PSL AUX NPRO controller.

- Bring the PSL AUX to Y End. However, some experiments with that laser are on going.

- Bring an NPRO combo back from UCB. UCB has borrowed an NPRO combo. We heard that it is coming back soon.

[Yuta, JC]

Yuta and I tested at the Y End for Green Beam

Yuta and I went over the the Yend to check on the green laser. Yuta and I tried a couple of test to see if there was a quick fix. 

· We used an ohm meter to check if the red interlock switch was working. (Beeps when pulled and silent when pushed.) The Interlock switch is working just fine. 
· We tried another laser that we found in the laser cabinet along the Y arm. This was a Lumentum 125 that said “5mW power (DYING!!!!)” on it. When we connected this to the controller, the laser did not turn on. I’m assuming that whoever labeled this laser “Dying” would have put “Dead” if the laser stopped working. So the laser should work, right ? 

Overall, we can rule out the interlock issue. It should be something with the controller, or the head. Though if we assume the laser works fine, the controller may be the issue. If we can make sure this spare Lumentum 125 works, this will mean that our laser at Y End is still alive. Is there anywhere I can test this ?

• ETMX damping loops are not good. ETMX is moving by ~10 urad (if oplev is correctly calibrated), and beam spot moves by ~0.5 beam spot on ETMX when Xarm is locked. TRX fluctuates by ~10%. Simply tuning gains did not solve.
• ETMX does not come back after putting some offset to misalign and remove the offset to align. Hysterisis makes me hysteric.
• Xend acromag is removed, and we cannot access Xend shutter and ETMX slow channels.
• XARM ASS is not working.
• Yend laser is not working.

[Koji, JC]

Koji and I had a walkthrough of the Y Arm and raised questions of what accommodations we can make for the lab. 

· The HP3563A Control System Analyzer - is this needed in the lab ? Has anyone used this ?
· We have the black instrument rack the is behind 1X2 Rack. We can move this by Section Y8 of the beam tube, where the step ladders are stored currently.
· We will remove the bulky cart from the lab space. This has been used consistently to store items on and forget about. It is better to not have it at all.
· The small optical breadboard which is along Y-Arm should be prepared for usage. Cardboard boxes under the table will be searched through and put into a google sheet. 
· Save the 1U cases from the modules that are by section Y10.
· Cleanroom garments and wardrobes should be moved by the dress area along Y arm. 
    ·Issue : We are currently using 3 cabinets along the Y arm for Cleanroom apparel. 
·There are HEPA Filter replacements under section Y11. We should swap these out with the mobile HEPA Booth because these filters have been in air and most likely aren’t as clean as they should be anymore. This will be done before our next vent. 
· Koji and I agreed that 6ft x 4ft is a good Length and Width for the cleanroom that is being assembled. This will give us ~1 ft of clearance on 3 sides of the table. 

[Yuta, Hiroki]

Calibrations of the actuators have been done

Summary of calibration:

AS55_Q in MICH : 1.16e9 counts/m 
BS        : 26.19e-9 /f^2 m/counts
ITMX    : 5.07e-9 /f^2 m/counts
ITMY    : 4.80e-9 /f^2 m/counts
ETMX  : 10.99e-9 /f^2 m/counts (matched to ETMY with the gain of "x0.414" put in coil outputs filter bank. Without "x0.414", 26.52e-9 /f^2 m/counts was measured.)
ETMY  : 10.99e-9 /f^2 m/counts
MC2    : -14.27e-9 /f^2 m/counts in arm length
MC2    : 5.10e-9 /f^2 m/counts in IMC length
MC2    : 1.06e+5 /f^2 Hz/counts in IR laser frequuency 

Methods

Calibration of MICH error signal:
To calibrate the MICH error signal (C1:LSC-AS55_Q_ERR), we followed the same free swinging method as elog #17285 and #16929 but used the update code: scripts/CAL/OpticalGain/getOpticalGain.py.
By fitting the X-Y plot of AS55_Q and  ASDC, we obtained 1.16e9 counts/m (Attachement 1).

Actuator calibration of BS, ITMX and ITMY:
We followed the same method as elog #17285 and #16929. 
We locked the MICH with UGF of ~10 Hz and measured the transfer function from C1:LSC-BS,ITMX,ITMY_EXC to C1:LSC-AS55_Q_ERR above the UGF.
By using the optical gain, measured transfer functions were calibrated to the actuator transfer functions of BS, ITMX and ITMY (Attachment 2).
Fitting code: scripts/CAL/MICH/MICHActuatorCalibration.ipynb

Actuator calibration of ETMX, ETMY and MC2:
We locked the X(Y)ARM with ITMX(Y) and measured the transfer function from C1:LSC-ITMX(Y)_IN2 to C1:LSC-X(Y)ARM_IN1. 
With this measurement, we can directly obtain the transfer function of (Optical gain)*(Actuator of ITMX(Y)), which is not affected by the 1/(1+OLTF) suppression (We should have done the same method for the calibration of BS, ITMX and ITMY).
Then we changed the actuator to ETM(X) and MC2 and measured the transfer functions from C1:LSC-ETMX(Y),MC2_IN2 to C1:LSC-X(Y)ARM_IN1. respectively (Attachment 3,4).
By fitting the ratios between the measured transfer functions, we obtained the actuator transfer functions of ETMX, ETMY and MC2 (Attachment 5,6,7).
Saved diaggui templates: measurements/LSC/(XARM;YARM)/(XARM;YARM)_(ITMX,ETMX,MC2; ITMY,ETMY,MC2)EXC_Template.xml

Balancing the actuation of ETMX and ETMY:
The obtained actuator transfer function of ETMX(Y) was 26.52e-9(10.99e-9) /f^2 m/counts.
The result for ETMY was consistent with elog #16977 but that for ETMX was ~10 times larger than elog #16977 because of the new ETMX coil driver.
To balance the ETMX and ETMY, we added the gain of “x0.414” to the coil output filter bank of ETMX.
Also, in order not to change the OLTFs, we added the gain of “x2.42” to the LOCK FILTERS of ETMX and changed the gain values of the damping filters.

Manually switched TP2 to "Low Speed (LS)" mode (aka "Stand by")

[Yuta, Yehonathan, JC]

We have moved a Smaller Table and moving forward with preparing a clean room.

What we did:
  - Moved the 3 ft x 4 ft Optical table which was by the red toolbox next to the 1X2 Power Supply Rack.
  - Moved the Portable HEPA Filter (which was used during the BHD Vent) from ITMX Chamber

Summary:

     · Moved the 3 ft x 4 ft Optical table which was by the red toolbox next to the 1X2 Power Supply Rack.

Yehonathan and I cleared off this table and disconnected any power connections that were running to it. There was a grounding cable that was bolted down to it and safely removed. Next, I used the manual forklift to lift one side of the table while Yehonathan rolled a piano dolley under the table support. Following, we did the similar procedure on the other side of the table and safely sat the table onto piano dolleys. We rolled the table over and placed it into it's new position by the 1X2 Power rack. To take off the piano dolleys, I used the forklift once again. Yehonathan held one side still to prevent the table from rolling away dangerously, and Yuta slid the Piano dolley out from under the table. Next, we lifted the other side and slipped the other dolley out of the table similarly. once the table was sat down, we re-leveled the table.

     ·Moved the Portable HEPA Filter (which was used during the BHD Vent) from ITMX Chamber

I rolled over the the protable HEPA filter from ITMX Chamber. The height of this was too tall to clear the short ceiling by the PSL table. Yuta and I have to lean the HEPA sideways to clear this and we did so smoothly. The HEPA fit perfectly around the optical table. I will wipe down the table contact Maty to see if we have a proper cleaning procedure for this. I would prefer to add more of the plastic drapes to enclose the table, but we can use plastic Mylar sheets in the mean time. 

I modified the Binary Input DB9 connector. The coil drivers are now operating with the Run/Acq LED off. As per 17656 they should have a flat TF now.

"gain_offset" for ETMY coil outputs has been turned on

As mentioned in elog #17671, the "gain_offset" of gain(0.48) for ETMY coil outputs had been turned off for some reason.
I have turned on all of the "gain_offset" for ETMY coils and have changed the alignment offsets for ETMY to compensate the effect of "gain_offset": 

P: 2703 -> 5631
Y: -2296 -> -4783

After the operation above, I confirmed that the Y arm is flashing and the OPLEV laser is hitting on the QPD.

[andrei, advait]

We wrapped the puck in foam. We also performed a calibration on the AD590 sensors @ 25.3 Celsius and then proceeded with an additional 6-point calibration using a digital thermometer (DT310LAB).

This is the current setup There is also a lid similar in size with the bottom lid, and the entire foam is currently held together with a heavy wire role that was put on top of the lid.

We couldn't replace the red tape with the yellow-transparent tape because the yellow tape is not strong enough and an air gap forms between the resistor and the puck. As a result, we will avoid getting above ~45 Celsius in to prevent the red tape from becoming too hot. We are now proceeding with a step response measurement and will follow up on that soon.

[Yuta, Hiroki]

BHD alignment has been restored

We aligned the AS beam (reflection of ITMX) and LO beam and maximized the fringing of the BHD differential signal (Attachment 1).
We used LO1, SR2 and AS4 for the alignment and the result parameters are shown in Attachment 2.
 

Procedure log of BHD alignment

Alignment of LO beam:

• ETMY, ETMX and ITMY were misalinged during this BHD alignment
• Misaligned SR2 to have only the LO beam in BHD DCPDs
• Tuned LO1 so that the LO beam comes to the previous position in the video

Alignment of AS beam:

• Restored SR2
• Tuned AS4 so that the AS beam comes to the position of LO beam
• Repeated the followings for the pitch and the yaw until the fringing was maximized:
  • Misaligned AS beam using SR2
  • Restore the alignment of AS beam using AS4
  • If the fringing gets worse, it means that you moved SR2 in the wrong direction. Move the SR2 in the opposite direction next and repeat the procedures above.
  • If the fringing gets better, it means that you moved SR2 in the correct direction. Continue the procedures above.

Before any trial at the ETMX suspension, ETMX coil driver "Run" mode (a sort of dewhitened mode) is ON at the coil driver. The "Binary Input" short plugs should be modified to turn them to "Run" mode.

IFO alignment is in a strange state.
BHD is not fringing, and misalignment script is not working properly

IFO alignment status
 - YARM ASS is working
 - XARM ASS is not working (because of ETMX coil driver upgrade)
 - Attached is the current alignment when YARM and XARM are both aligned, AS4 misaligned. Powers at photo diodes are as follows.

>cdsutils avg -s 10 C1:PSL-PMC_PMCTRANSPD C1:IOO-MC_TRANS_SUMFILT_OUT C1:LSC-TRY_OUT_DQ C1:HPC-BHDC_A_OUT C1:HPC-BHDC_B_OUT C1:LSC-TRX_OUT_DQ
C1:PSL-PMC_PMCTRANSPD 0.688543850183487 0.0010497113504850193
C1:IOO-MC_TRANS_SUMFILT_OUT 13378.8802734375 58.42096336275247
C1:LSC-TRY_OUT_DQ 1.0218201756477356 0.006230110889854089
C1:HPC-BHDC_A_OUT 34.033762741088864 0.1877582940472513
C1:HPC-BHDC_B_OUT 33.95858993530273 0.1951729492341625
C1:LSC-TRX_OUT_DQ 0.9446217834949493 0.01777568349190775

 - After this, we usually misalign ETMY, ETMX, ITMY to have LO-ITMX fringe in BHD DCPDs (elog #17277), but it seems like it is hard to see the fringe by aligning AS beam with SR2 and AS4 we usually use.
 - Also, misalign/restore script we use are not working properly. Alignment changes a lot when restored after misalignment.
 - We also found that "gain_offset" of gain(0.48) for ETMY coil outputs was turned off.  This changed the alignment offsets to get the correct alignment. This probably also affected LSC.

Next:
 - Recommission XARM ASS with updated ETMX coil driver
 - Check the "gain_offset" filter for ETMY and update relevant gains
 - Check the misalignment script.
 - Align LO-AS fringe

The incompleteness of burtrestore is a critical issue. We need to track down what is the issue.

[Yuta, JC]

We are restoring the IFO alignment back to Nominal operating state


What we did:
  - Fixed the IMC and got WFS back to running state.
  - Returned all TMs to there original postion using the OPLEVs
  - Used BurtRestore to bring back the C1:HPC.adl and C1:BAC.adc
  - Align the OPLEVs.

Summary:

To start off the morning, I began to work on IMC which became misaligned ~6:00am. IMC WFS seemed to be the issue, so I turned these off and pushed worked to align IMC manually (This took a ton of time). After aligning, Yuta came in and showed me how to fix IMC WFS and we got it to work again. the main issue being that "Clear History" was stuck for a bit and the offsets were stuck to insane values. 

Next we moved forward with viewing the BHD PDs. Yuta knew there was an issue with the BurtRestore Yehonathan and I did yesterday because there were no values on the C1:HPC.adl page. To fix this, in the terminal we typed --> 

~> cd /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2023/Jun/9

Now, you land in whichever date you chose, for us it was the 9th of June:

9> burtgooeyC1:HPC.adl
 
This will pull up BURT. from here go Restore-> Snapshot Files-> (Select your time) -> (Select which files you want to restore) -> Ok -> Cancel -> Restore. (Keywords: How to burtrestore )

This will restore the files of which you have chosen back to the date you selected.

Yuta and I restored C1:HPC.adl and C1:BAC.adl.

Following, now that all the BurtRestoring is done, we moved forward with aligning single arms. We had a very trashy mode on BHD and decided to align TT1 and TT2. 

I tried to align the Y arm to start off, but ETMy was acting very hectic. I was trying to align the OPLEVs to start off, but ETMY Oplev was VERY FAR OFF. It was very weird that I was moving YAW for a very good amount and yet the Red Beam would not move one bit in the YAW direction! I couldnt get it even close to hit the steering mirror to hit the ETMY_OPLEV_QPD. I asked Yuta for help and it turns out that the gain for the alignment offesets were 0! After Yuta found this, he restored the original offset values by using:

restoreAlignment -o ETMY -t 'now 14days'

(Keywords: How to restoreAlignment)

After this issue was fixed, I was able to align the OPLEV beam with ease and we started to get some flashing on the Y Arm. Yuta now has the Y Arm locked with flashing on the X Arm. We plan to align nicely and realign the OPLEVs before the end of the day.

SUS2 crashed again. I sshed into sus2 and tried:

Clicked on global diag reset, made everything green. Optics are still not damping.

Burt restored the sus2 epics to Jun 5 10:00. BHD optics seem to be damping. Vertex and MC optics are still not damping so I'm restarting all models.

./opt/rtcds/caltech/c1/Git/40m/scripts/cds/restartAllModels.sh

Got all models with DC red so I stopped all models.

./opt/rtcds/caltech/c1/Git/40m/scripts/cds/stopAllModels.sh

turned all the RTCDS on manually.

I restarted them again but the DC indicators were still red. JC clicked on Restart DAQD and that seemed to have solved the issue.

We had to restore manually burtrestore all epics for the suspensions screen to go back to normal reffering to elog 17315.

All optics seem to be damping except PR3. The damping loops are working but it moves to much. The same goes for LO2.

I fixed the issue with LO2 and PR3. Turned out the alignment biases were off for the BHD optics. I turned them on and all of them are damping nicely.

[JC, Radhika]

The vacuum system went down over the weekend due to a loss of N2 pressure (We are down to our last tank of N2). I have brought the vacuum system back up to nominal state.

I first changed the N2 cylinder and to suopply the valves. WITHOUT N2, THE VALVES WILL NOT OPEN.  Normal operation PSI for N2 is ~65-80 PSI, view this from C1:VAC-N2_pressure. After swapping out the tanks I proceeded to pump down the vacuum with a simple procedure,

- First, opened V4 and V5
- Open VASE, VASV, VABSSCI, VABSSCO, VAEV, VAEE
- Open VA6
- Open V1 to pump down the main volume.

All the turbopumps are running at nominal speed and we are pumping down nicely.

After recovering a transmissivity of ~7% for the 90-10 BS (in AC chopper configuration), I moved on to PR2. I mounted PR2 on a rotation stage to control the angle of incidence (AOI) [Attachment 1]. I did a quick check to see if transmitted light through the DUT was measureable on the TRANS PD on its existing gain setting (0 dB). It was, which means the dynamic range of the PD at that gain setting is large enough and the PD gain does not need to be adjusted when placing/removing the DUT. This simplified the transmissivity calculation, since the extra gain reference was no longer needed (the power reference from REF PD remains). The p-polarization setup can be seen in Attachment 2. For each AOI i:

.

During measurement, for each AOI I measured the spectra of the TRANS and REF PDs with the Moku:Go Spectrum Analyzer [Attachment 3]. I found their spectral peaks at f_test and f_ref respectively. Attachment 4 shows the p-polarization results for transmissivity vs. AOI. The blue points are calculated from the peak values found by Moku:Go spectrum analyzer; the orange points are calculated from manual peak finding from taking an FFT of the time-series data. Excluding the 45deg AOI, the transmissivies are below 1000 ppm and are even smaller if using the manual FFT analysis. I will tweak the setup for s-polarization measurements this afternoon.

Towards Vacuum Normal

• Closed V7 (Main volume pumped by TP1/TP2)
• Opened VA6 (Annuli pumped by TP3)

I kept having trouble controlling TP2 from EPICS. So, temporarily the controller was set to "FRONT" (PANEL) mode rather than "SERIAL" mode. This problem should be fixed.

[Mayank, Hiroki, Koji]

Once we reached 1~2mtorr, we opened the PSL shutter.

The IMC was immediately locked and aligned with the WFS.

The PRM/SRM looked very much aligned. We could see the MI and two arms fringing.

The two arms were manually aligned and the Y arm was aligned with the ASS.

40m has been transitioned to LASER HAZARD now.

PSL/ETMX/ETMY NPROs were turned on.
Radhika can turn on the PSL AUX laser.

ETMX OPLEV HeNe beam block was removed,

[Koji, Mayank, Hiroki]

As Mayank and Koji solved the issue of opening the gate valves yesterday (ID: 17661), we resumed pumping down the 40m vacuum.
We started the evacuation around 10AM and achieved 0.7 mTorr around 8PM (Attachment 1 and 2).

Procedure log for pumping down

Evacuation with rotary pumps:

• All valves were closed at first
• Opened all annluli (VASE, VASV, VABSSI, VABS, VABSSCO, VAEV and VAEE) and venting valve VAVEE
• Opened V7
• Turned on RP1 and RP2
• Opened V3
• Opened RV1 manually to evacuate the main volume
  • It took around 10 minutes to observe the gauge going down from 760 Torr
• Tuned RV1 so that the evacuation reaches the target speed: 3 Torr/min
  • RV1 needed to be almost closed to achieve this target speed
  • Evacuating speed was unstable

Leak check for annuli and main volume:

• Closed VAVEE
• Opened V6 and VA6
• Opened V3 (V3 had been closed by interlock) to evacuate the main volume
• Closed V6 and VA6
  • --> Pressure in annuli stayed stable. There seemed to be no leak in annuli.
• Closed RV1 completely and isolated the main volume to check the leak in main volume
  • --> Pressure was flat in average (but fluctuating)

Resumption of pumping down:

• Opened RV1 slightly so that the evacuation reaches the target speed: 3 Torr/min
  • RV1 status said "Closed" due to the slight opening
• Tuned evacuating speed with RV1 occasionaly as the speed got slower as time passed

Evacuation with turbopumps:

• ~0.36 Torr at 17:33
• Turned on the auxiliary rotary pump connected to TP2 and TP3 manually (not shown in diagram)
• Opened the valves between auxiliary rotary pump and TP2,3 manually
  • PTP2 and PTP3 are connected here. The diagram of C0VAC_CONTROL.adl is incorrect.
• Turned on TP3
• Turned on TP2 manually
  • TP2 remote control is not working
• Opened V5 when TP3 was ready (75krpm at this moment) 
• Opened V4 when TP2 was ready (66krpm at this moment)
• Closed RV2
• Turned on TP1 but TP1 did not start spinning
  • TP1 controller showed an error message on its front panel. We operated the controller manually and then turned on TP1 in C0VAC_CONTROL.adl.
  • --> Succeeded in spinning TP1
• Closed RV1 and V3
• Turned off RP1 and RP3
• Vented the manual RP line
• Opened V1 when TP1 was ready
• Opened RV2 slightly until PTP2 and PTP3 said around 1Torr in order not to trip the interlock
  • Pressure in main volume decreased at slow rate (2 mTorr/min)

Simultaneous use of turbopumps and rotary pumps:

• Evacuating speed with rotary pumps just before turning on the turbopumps was around 10 mTorr/min (faster than turbo). So we decieded to use the rotary pumps as well again.
• Set up and turned on the rotary pump system again
• With simultaneous evacuation with rotary pumps and turbopumps, evacuating speed got faster: 5 mTorr/min
• Turned off and vented the rotary pump system when the speed decreased to 2 mTorr/min

Continuing evacuation with turbopumps:

• For faster evacuation, we occasionaly adjusted the RV2 manually until PTP2 and PTP3 said around 1 Torr
• We reched 0.7 mTorr at 20:15.

[Mayank, Hiroki, Yuta, JC, Koji]

After JC came back from the optical table placement at Synchrotron, we tried to pump down the 40m vacuum.
However, we were unable to change the gate valves.

After many hours of struggle, it was fixed. It turned out that there was an error associated with an old CERT certificate (!).

Up to a certain point we were able to operate the gate valve, but (in hindsight) after having operated the V3 valve and tripped the vacuum interlock, we could no longer operate the gate valves.
The confusing thing was that we still could switch some of the switches like the rotary pumps. So we suspected some Acromag error or something like that. (But it wasn't)

We tried to reboot c1vac and Acromag chassis, but it did not solve the issue. Moreover JC noticed that the interlock status got stuck at "DOWN" mode. We were not sure if not running the interlock and the issue of the gate valves were related or not. At ~5PM we decided to postpone today's pumping down.

Mayank and I continued to troubleshoot the issue. What we found was CERT certificate verify issue:
Jun 27 18:35:37 c1vac python[15916]: ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)

This prevented "Interlock.py" from running. I further went into the cause of this error and found that:

• When the interlock is activated, an e-mail notification is sent out.
• The email contains the timestamp of the incident.
• The timestamp was generated with gpstime library.
• When gpstime is called, it accesses a website to download the leap second table.
• But CERT certification verify failed for some reason.

This gpstime was replaced with datetime.

controls@c1vac:/opt/target/python/interlocks$ diff mailer.py.orig mailer.py
11c11,12
< import gpstime
---
> #import gpstime
> from datetime import datetime
80c81,83
<     now = gpstime.tconvert(gpstime.tconvert('now'))
---
>     #now = gpstime.tconvert(gpstime.tconvert('now'))
>     nowDT = datetime.now()
>     now = nowDT.strftime("%d/%m/%Y %H:%M:%S")

After this modification and restarting the interlock service (sudo systemctl restart interlock.service on c1vac), the interlock state turned from DOWN to Running, and we recovered control of the gate valves!

[Many]

The large optical table (5ft x 12ft x 2ft, previously called SP table) was moved from the 40m lab. (Attachment 1)
The contractor did a professional job and successfully transported the optical plate to the Synchrotron building without damaging the 40m facility.

JC came early in the morning to work on the final preparations. Some others were on standby at 8 AM. The arrival of the contractor got delayed due to traffic. The actual work began at 10 AM.

(10AM) The contractor first spent ~90min assembling a hoist around the optical table. It was necessary to remove some fluorescent light tubes and their covers because of the height of the hoist. (Attachment 2)

(11:30AM) Once the hoist was assembled, the optical table was tilted vertically using a sling and a chain block. (Attachment 3)

(12AM) The table was placed on dollies narrower than the table width (2ft) and rolled to the south end door. Thanks to our careful preparation, this process was smooth and took only 10 minutes. (Attachment 4)
A compact forklift was used to get over the end door (Attachment 5). Once half of the table was exposed outside, a larger forklift lifted the entire table and swung it out from the lab building (Attachment 6). After it was tipped horizontally, it was laid on a gigantic truck with the same forklift (Attachments 7/8). (1 PM)

The photos and videos are collected in the 40m google photo.

40m Lab is now Laser Safe

- The PSL NPRO (Innolight) was turned off with the OFF switch and the key. The LD set current was 2.100A. The crytsal temp setpoint was 30.61degC.
  The PSL AUX NPRO (LWE) was already off.

- The South End NPRO (Innolight) was found to be off (why!?). Check the LD set current to be 1.990A. The crytsal temp setpoint was 32.86degC.
  ETMX Oplev HeNe was blocked in front of the head.

- The East End NPRO (LWE) did not accept the inspection showing "CABLE?" error. Turned it off and the controller DB cable was re-fastened. This allowed to check the settings. THe current adj was 0. The crytsal temp setpoint was 43.6010degC.

- Pushed the PSL table emergency laser shut-off to turn off the laser warning signs. Note that the control room laser warning sign is not lit. Is that normal?

[Yehonathan, Mayank, Hiroki, JC, Koji]

Vent prep from 10AM

• IMC/arms are flashing / PRM / SRM aligned / BHD LO visible on the BHD camera
• Oplevs aligned (Attachment 1)
• OSEM values recorded (Attachment 2)

1PM after lunch

• PSL Shutter closed
   
• V1 closed to isolate the main vacuum manifold
• VA6 closed to isolate the annuli
• VM3 closed VM3 to isolate the RGA
• V7 opened to unify the pump spool
• VAVEE opened to vent annuli
• Stopped TP3 from the vacuum medm screen
• Tried to stop TP2 from the screen, but the controller did not respond. TP2 is still running.
  • To turn off TP2, the controller mode was turned to "FRONT" mode. This was done by entering the menu mode with the upper two buttons pushed together for ~2sec.
  • Once TP2 stopped, the controller mode was returned to "RS232" mode, and it seems that this recovered the communication with the medm screen.
• After stopping TP2 and TP3, the valves for them were closed and the AUX dry pump was turned off.

1PM after lunch

• Connected an N2 cylinder
• Introduced the N2 with 3mTorr/min at the beginning, then 6mTorr/min. Then 10mTorr/min after some adjustment. Gradually increased the vent rate. 200mTorr/min at 2Torr. 1Torr/min at 15Torr.
• Vent t=1hr P=145Torr
• The vent unexpectedly finished 10min after I checked the pressure at 270 Torr. In ~5min, while no one was watching the P trend, the pressure increased by ~500 Torr. How can it be possible? According to the N2 cylinder, it has ~300 cft of N2 at 1atm. It is definitely not enough to fill the both arms + chambers. Attachment 3 shows how the pressure increased. It was almost like an exponential increase... where does this gas coming?
• We checked if the main volume was at 1atm or not. It seemed that it was already filled.

There were a few scripts linked on the IFO ALIGN screen. These silently ran ASS and leave (possible) offsets in ASS. When the script was run secondtime, the manual alignment was destroyed.
I deleted them from the screen as they were harmful.  

I  measured the transfer function of the new coil driver board. This was done to estimate the correct Sim-Dewhithinng and Anti-Dewhitening digital filters in the CDS. 

Attachment 1: Shows the setup used to measure the TF of the Coil driver board.
Attachment 2: Coil driver board replaced by a DB9 cable (Reference).
Attachment 3: The magnitude and phase response of the measured and simulated TF (Coil driver parameters mentioned here (D2100145) )

Update

Attachment 4: The magnitude and phase response of the simulated and measured TF for the two operating modes. (The coil driver has two modes of operation i.e. Run and Acuisition)