It was indeed the issue of the top OSEM plate not being in the right place horizontally. But the issue was more non-trivial. I believe because of the wedge in thick optics, there is a YAW offset in the optic in the free hanging position. I had to readjust the OSEM plate 4 times to be able to get full dark to bright range in both upper OSEMs. After doing that, I tuned the four OSEMs somewhat near the halfway point and once I was sure I'm inside the sensitive region in all face OSEMs, I switched on POS, PIT, and YAW damping. Then I was able to finely tune the positions of both upper OSEMs.

However, on reaching to lower right OSEM, I found again the same issue. I had to stop to go to the 40m meeting, I'll continue this work in the afternoon. But OSEM plate adjustment in the horizontal direction, particularly for thick optics is required to be done before transporting them. I achieved the best position by turning the OSEM 90 degrees and using the OSEM LED/PD plates to determine the position. This was the final successful trial I did in adjusting the plate position horizontally.

[Paco, Tega, Anchal]

Today, we started work on AS4 SOS by checking the OSEM and cable. Swapping the connection preserved the failure (no counts) so we swapped the long OSEM for a short one that we knew was working instead, and this solved the issue. We proceeded to swap in a "yellow label", long OSEM in place and then noticed the top plate had issues with the OSEM threads. We took out the bolt and inspected its thread, and even borrowed the screw from PR2 plate but saw the same effect. Even using a silver plated setscrew such as the SD OSEM one resulted in trouble... Then, we decided to not keep trying weird things, and took our sweet time to remove the UL, UR OSEMs, top earthquake stops, and top plate carefully in-situ. Then, we continued the surgery by installing a new top plate which we borrowed from the clean room (the only difference is the OSEM aperture barrels are teflon (?) rather than stainless. The operation was a success, and we moved on to OSEM installation.

After reaching a good place with the OSEM installation, where most sensors were at 50% brightness level and we were happy with the damping action (!!), we fixed all EQ stops and proceeded to push the SOS to its nominal placement. Then upong releasing the EQ stops, we found out that the sensor readings were shifted.

Is this the correct status? Please directly update this entry.

LO1 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
LO2 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
AS1 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
AS4 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
PR2 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
PR3 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
SR2 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]

Last updated: Fri Jan 28 10:34:19 2022

I have further updated my calculation. Please find the results in the attached pdf.

Following is the description of calculations done:

Arm cavity reflection:

Reflection fro arm cavity is calculated as simple FP cavity reflection formula while absorbing all round trip cavity scattering losses (between 50 ppm to 200 ppm) into the ETM transmission loss.

So effective reflection of ETM is calculated as

The magnitude and phase of this reflection is plotted in page 1 with respect to different round trip loss and deviation of cavity length from resonance. Note that the arm round trip loss does not affect the sign of the reflection from cavity, at least in the range of values taken here.

PRC Gain

The Michelson in PRFPMI is assumed to be perfectly aligned so that one end of PRC cavity is taken as the arm cavity reflection calculated above at resonance. The other end of the cavity is calculated as a single mirror of effective transmission that of PRM, 2 times PR2 and 2 times PR3. Then effective reflectivity of PRM is calculated as:

Note, that field transmission of PRM is calculated with original PRM power transmission value, so that the PR2, PR3 transmission losses do not increase field transmission of PRM in our calculations. Then the field gain is calculated inside the PRC using the following:

From this, the power recycling cavity gain is calculated as:

The variation of PRC Gain is showed on page 2 wrt arm cavity round trip losses and PR2 transmission. Note that gain value of 40 is calculated for any PR2 transmission below 1000 ppm. The black verticle lines show the optics whose transmission was measured. If V6-704 is used, PRC Gain would vary between 15 and 10 depending on the arm cavity losses. With pre-2010 ITM, PRC Gain would vary between 30 and 15.

LO Power

LO power when PRFPMI is locked is calculated by assuming 1 W of input power to IMC. IMC is assumed to let pass 10% of the power (). This power is then multiplied by PRC Gain and transmitted through the PR2 to calculate the LO power.

Page 3 shows the result of this calculation. Note for V6-704, LO power would be between 35mW and 15 mW, for pre-2010 ITM, it would be between 15 mW and 5 mW depending on the arm cavity losses.

The power available during alignment is simply given by:

If we remove PRM from the input path, we would have sufficient light to work with for both relevant optics.

I have attached the notebook used to do these calculations. Please let me know if you find any mistake in this calculation.

Today I suspended AS1. Anchal helped me with the initial hanging of the optics. Attachments 1,2 show the roll balance and side magnet height. Attachment 3 shows the motion spectra.

The major peaks are at 668mHz, 821mHz, 985mHz.

For some reason, I was not able to balance the pitch with 2 counterweights as I did with the rest of the thin optics (and AS1 before). Inserting the weights all the way was not enough to bring the reflection up to the iris aperture that was used for preliminary balancing. I was able to do so with a single counterweight (attachment 4). I'm afraid something is wrong here but couldn't find anything obvious. It is also worth noting that the yaw resonance 668mHz is different from the 755mHz we got in all the other optics. Maybe one or more of the wires are not clamped correctly on the side blocks?

The OSEMs were pushed into the OSEM plate and the plates were adjusted such that the magnets are at the center of the face OSEMs. The wires were clamped and cut from the winches. The SOS is ready for installation.

Also, I added a link to the OSEM assignments spreadsheet to the suspension wiki.

I uploaded some pictures of the PEEK EQ stops, both on the thick and thin optics, to the Google Photos account.

After some work on the reference database file, we now have a template for temporary watchdog implementation for LO1 located here "/cvs/cds/caltech/target/c1susaux/C1_SUS-AUX_LO1.db".

Basically, what I have done is swap the EPICS asyn analog input readout for the COIL and OSEM to accessible medm channels, then write out watchdog enable/disable to coil filter SW2 switch. Everything else in the file remains the same. I am worried about some of the conversions but the only way to know more is to see the output on the medm screen.

To test, I restarted c1su2 but this did not make the LO1 database available, so I am guessing that we also need to restart the c1sus, which can be done tomorrow.

As the new db is made for c1susaux, 1) it needs to be configured to be read by c1susaux 2) it requires restarting c1susaux 3) it needs to be recorded by FB 4) and restartinbg FB.
(^-Maybe not super exact procedure but conceptually like this)

cf.
https://wiki-40m.ligo.caltech.edu/How_To/Add_or_rename_a_daq_channel

IMC is not such lossy. IMC output is supposed to be ~1W.

The critical coupling condition is G_PRC = 1/T_PRM = 17.7. If we really have L_arm = 50ppm, we will be very close to the critical coupling. Maybe we are OK if we have such condition as our testing time would be much longer in PRMI than PRFPMI at the first phase. If the arm loss turned out to be higher, we'll be saved by falling to undercoupling.
When the PRC is close to the critical coupling (like 50ppm case), we roughly have Tprc x 2 and Tarm to be almost equal. So each beam will have 1/3 of the input power i.e. ~300mW. That's probably too much even for the two OMCs (i.e. 4 DCPDs). That's OK. We can reduce the input power by 3~5.

I was wondering whether I should take AS1 down to redo the wire clamping on the side blocks. I decided to take the OpLev spectrum again to be more certain. Attachments 1,2,3 show 3 spectra taken at different times.

They all show the same peaks 744mHz, 810mHz, 1Hz. So I think something went wrong with yesterday's measurement. I will not take AS1 down for now. We still need to apply some glue to the counterweight.

[Paco]

Turns out, the shifting was likely due to the table level. Because I didn't take care the first time to "zero" the level of the table as I tuned the OSEMs, the installation was b o g u s. So today I took time to,

a) Shift AS4 close to the center of the table.

b) Use the clean level tool to pick a plane of reference. To do this, I iteratively placed two counterweights (from the ETMX flow bench) in two locations in the breadboard such that I nominally balanced the table under this configuration to zome reference plane z0. The counterweight placement is of course temporary, and as soon as we make further changes such as final placement of AS4 SOS, or installation of AS1, their positions will need to change to recover z=z0.

c) Install OSEMs until I was happy with the damping. ** Here, I noticed the new suspension screens had been misconfigured (probably c1sus2 rebooted and we don't have any BURT), so quickly restored the input and output matrices.

SUSPENSION STATUS UPDATED HERE

The main issue with SR2 OSEMs, now that I think of it, was that the BS table was very inclined due to the multiple things we removed (including counterweights). Today the first I did was level the BS table by placing some counterweights in the correct positions. I placed the level in two directions right next to SR2 (clamped in its planned place), and made the bubble center.

While doing do, at one point, I was trying to reach the far South-West end of the table with the 3x heavy 6" cylindrical counterweight in my hand. The counterweight slipped off my hand and fell from the table. See the photo in attachment 1. It went to the bottommost place and is resting on its curved surface.

This counterweight needs to be removed but one can not reach it from over the table. So to remove it, we'll have to open one of the blank flanges on the South-west end of BS chamber and remove the counterweight from there. We'll ask Chub to help us on this. I'm sorry for the mistake, I'll be more careful with counterweights in the future.

Moving on, I tuned all the SR2 OSEMs. It was fairly simple today since the table was leveled. I closed the chamber with the optic free to move and damped in all degrees of freedom.

Photos: https://photos.app.goo.gl/CQ6VouSB1HX2DPqW6

SUSPENSION STATUS UPDATED HERE

Temp software watchdog now operational for LO1 and the remaining optics!

Koji helped me understand how to write to switches and we tried for a while to only turnoff the output switch of the filters instead of the writing a zero that resets everything in the filter.

Eventually, I was able to move this effort foward by realising that I can pass the control trigger along multiple records using the forwarding option 'FLNK'. When I added this field to the trigger block, record(dfanout,"C1:SUS-LO1_PUSH_ALL"), and subsequent calculation blocks, record(calcout,"C1:SUS-LO1_COILSWa") to record(calcout,"C1:SUS-LO1_COILSWd"), everything started working right.

The PR2 candidate V6-704/705 mirrors (Qty2) are now @Downs. Camille picked them up for the measurements.

To identify the mirrors, I labeled them (on the box) as M1 and M2. Also the HR side was checked to be the side pointed by an arrow mark on the barrel. e.g. Attachment 1 shows the HR side up

AS4 is set to go through a free swinging test at 10 pm tonight. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

SR2 is set to go through a free swinging test at 3 am tonight. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on theSR2 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/SR2 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks.

1.09

0.914

0.622

0.798

-0.977

1.249

0.143

-1.465

-0.359

0.378

0.552

-1.314

-0.605

1.261

0.118

0.72

0.403

0.217

0.534

3.871

The new matrix was loaded on SR2 input matrix and this resulted in no control loop oscillations at least. I'll compare the performance of the loops in future soon.

All done (almost)! I still have not sorted the issue of pitch and yaw gains growing together when modified using ramping time. Image of custom ADC and DAC panel is attached.

Camille@Downs measured the surface of these M1 and M2 using Zygo.

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the AS4 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/AS4 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks.

0.844

0.707

0.115

0.253

-1.646

0.122

0.262

-1.319

-1.459

0.214

1.087

-0.901

-0.874

1.114

0.016

0.622

0.934

0.357

0.045

3.822

The new matrix was loaded on AS4 input matrix and this resulted in no control loop oscillations at least. I'll compare the performance of the loops in future soon.

I updated the mime.local.conf file for the AIC Wiki so as to allow attachments with the .txz format. THis should be persistent over upgrades, since its a local file.

[Ian, Tega]

Connected the New SUS screens to the controller for the simplant model. Because of hard-coded links in the medm screen links, it was necessary to create the following path in the c1sim computer, where the new medm screen files are located:

We noticed a few problems:

1. Some of the medm files still had C1 hard coded, so we need to replace them with $IFO instead, in order for the custom damping filter screen to be useful.

2. The "Load coefficient" button was initially blank on the new sus screen, but we were able to figure out that the problem came from setting the top-level DCU_ID to 63.

[TODO]

Get the data showing the controller damping the pendulum. This will involve tweaking some gains and such to fine-tune the settings in the controller medm screen. Then we will be able to post some data of the working controller.

[Useful aside]

We should have a single place with all the instructions that are currently spread over multiple elogs so that we can better navigate the simplant computer.

I think our suspension input matrix diagonalization is not so robust usually because we only choose a inverting matrix which gives the best separation for a single suspension alignment.

i.e. we have seen in the past that adjusting the bias for the alignment makes the matrix inversion not work well. Sometime people turn OFF the alignment bias before making the ringdown and that makes the whole measurement invalid.

This is because the sensitivity of the OSEMs to longitudinal and/or transverse motion is significantly different for different alignment.

I wonder if there's a way we can choose a better matrix by putting in random gain errors on the shadow sensor signals and then finding the matrix which gives the best diag under an ensemble of gain errors.

I picked up the PR2 mirrors (labeled M1, M2) from Anchel's table and took them to the cleanroom. By inspection, I spotted some dust particles on M1. I wasn't able to remove them with clean air so I decided to use M2 which looked much cleaner. I wasn't able to discern any wedge angle on the optic. I inserted the optic into a thin optic adapter. The optic is thicker than I expected so I use long screws for the mirror clamping. I expect that the pitch balance will shift towards the front of the mirror so I assembled only 1 counterweight for now. The side blocks with wires in them were installed.

I engraved the SOS and installed the winches on it. Paco came in and helped me to hang the optic. Looking at the wire hanging angle I realize that 1 counterweight at the front is not enough. I install a second counterweight at the back and observe that I can cross the balancing point.

I locked the EQ stops. Suspension work continues tomorrow...

I placed LO2 in its planned position in BS chamber, inserted the OSEMs, and tuned their position to halfway brightness. At the end of the work, I was able to damp the optic successfully. The full open (full brightness) OSEM ADC counts are:

UL 25743.  -> 12876
UR 27384. -> 13692
LL 25550. -> 12775
LR 27395 -> 13697
SD 28947 -> 14473

Today's OSEM tuning was relatively unhappening. I have only following two remarks:

• BS table was 3 SOS near the East end and PRM is parked in the center, thus the table is very unevenly balanced. I had to use all available counter weights to make it flat near the LO2 suspension.
• The side OSEM for LO2 is not exactly centered (probably due to table imbalance). I was able to balance the table to a point though that the side OSEM was responsive to full range and I was able to damp the optic.

Free swinging test set to trigger

LO2 is set to go through a free swinging test at 10 pm tonight. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

Photos: https://photos.app.goo.gl/Ff3yGBprj9xgPbnLA

SUSPENSION STATUS UPDATED HERE

I agree. That's an interesting idea. But does that mean that there is an always working inverse matrix solution or that any solution will be vulnerable to the alignment biases.

I think we can also calculate the matrix rotation required as a function of dc biases and do that rotation in the simulimk model.

[Paco]

AS1 was installed in the ITMY chamber today. For this I moved AS4 to its nominal final placement and clamped it down with a single dog clamp. Then, I placed AS1 near the center of the table, and quickly checked AS4 could still be damped. After this, I leveled the table using a heavier/lighter counterweight pair. 

Once things were leveled, I proceeded to install AS1 OSEMs. The LL, UL, UR OSEMs had a bright level of 27000 counts, while SD and LR were at 29500, and 29900 respectively. After a while, I managed to damp all degrees of freedom around the 50% thousand count levels, and decided to stop. 

UL 27000.  -> 16000
UR 27000. -> 13800
LL 27000 -> 14600
LR 29900 -> 14900
SD 29500 -> 12900

Free swinging test set to trigger

AS1 is set to go through a free swinging test at 3 am this evening. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

SUSPENSION STATUS UPDATED HERE

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the LO2 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/LO2 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks.

0.46

1.237

1.094

0.318

0.98

1.091

0.252

-1.512

-0.672

-0.088

0.722

-1.014

-0.217

1.519

0.314

-0.747

1.523

1.737

-0.534

3.134

The new matrix was loaded on LO2 input matrix and this resulted in no control loop oscillations at least. I'll compare the performance of the loops in future soon.

For some reasonf the free swing test showed only one resonance peak (see attachment 1). This probably happened because one of the earthquake stops is touching the optic. Maybe after the table balancing, the table moved a little over its long relazation time and by the time the free swing test was performed at 3 am, one of the earthquake stops was touching the optic. We need to check this when we open the chamber next.

I noticed that our current suspension damping loops for the new SOS were railing the DAC outputs. The reason being that cts2um module has not been updated for most optics and thus teh OSEM signal (with the new Sat Amps) is about 30 times stronger. That means our usual intuition of damping gains is too high without applying correct conversion cts2um filter module. I reduced all these gains today and nothing is overflowing the c1su2 chassis now. I also added two options in the "!" (command running drop down menu) in the sus_single medm screens for opening ndscope for monitoring coil outputs or OSEM inputs of the optic whose sus screen is used.

PR2's side magnet height was adjusted and its roll was balanced (attachment 1,2). I verified that the OpLev beam is still aligned. The pitch was balanced: First, using an iris for rough adjustment. Then, with the QPD. I locked the counterweight setscrew.

I turned off the HEPAs, damped PR2, and measured the QPD spectra (attachment 3). Major peaks are at 690mHz, 953mHz, and 1.05Hz. I screwed back the lower OSEM plate. The wires were clamped to the suspension block and were cut. Winch adapter plate removed. I wanted to push OSEMs into the OSEM plates but the wiki is down so I can't tell what was the plan. This will have to wait for tomorrow. Also here like with AS1 we need to apply glue to the counterweights.

[Paco]

This morning, I went into ITMY chamber to inspect AS1 after the free swinging test failed. Indeed, as forecasted by Anchal, the top front EQ stop was slightly touching, which means AS1 was not properly installed before. I proceeded by removing it well behind any chance of touching the optic, and did the same for all the other stops, of which most were already recessed significantly. Finally, the OSEMs changed accordingly to produced a PITCHed optic (top front EQ was slightly biasing the pitch angle), so I did a reinstallation until the levels were around the 14000 count region. After damping AS1 relatively quickly, I closed the ITMY chamber.

[Ian, Paco, Tega]

Last night we set up the four main matrices that handle the conversion between the degrees of freedom bases and the sensor bases. We also wrote a bash script to automatically set up the system. The script sets the four change of bases matrices and activates the filters that control the plant. this script should fully set up the plant to its most basic form. The script also turns off all of the built-in noise generators. 

After this, we tried damping the optic. The easiest part of the system to damp is the side or y motion of the optic because it is separate from the other degrees of freedom in both of the bases. We were able to damp that easily. in attachment 1 you can see that the last graph in the ndscope screen the side motion of the optic is damped. Today we decided to revisit the problem.

Anyways, looking at the problem with fresh eyes today, I noticed the in pit2pit coupling has the largest swing of all the plant filters and thought this might be the reason why the inputs (UL,UR,LR,LL) to the controller was hitting the rails for pit DoF. I reduce the gain of the pit2pit filter then slowly increased it back to one. I also reduced the gain in the OSEM input filter from 1 to 1/100. The attached image (Attachment2) is the output from this trial. This did not solve the problem. The output when all OSEM input filter gain set to one is shown in Attachment2.

We will try to continue to tweak the coefficients. We are probably going to ask Anchal and Paco to sit down with us and really hone in on the right coefficients. They have more experience and should be able to really get the right values.

[Anchal, Paco]

We removed the old PR3 housed in a tip-tilt style suspension and put it on the North flow bench in the cleanroom. I put PR3 in an accessible position near the North West edge of the BS chamber and balanced the table again with many weights. The OSEM tuning was very uneventful and easy. Following are the full brightness ADC counts for the OSEMs:
UL 25693. -> 12846
UR 24905. -> 12452
LL 23298. -> 11649
LR 24991. -> 12495
SD 26357. -> 13178

I was able to damp the optic easily after the OSEM installation with no issues.

Photos: https://photos.app.goo.gl/jcAqwFJoboeUuR7F9

[Paco, Anchal, Tega]

After installing the short OSEMs into PR2, we moved it into ITMX Chamber. While Tega loaded some of the damping filters and other settings, we took time to balance the heavily tilted ITMX chamber. After running out of counterweigths, Anchal had to go into the cleanroom and bring the SOS stands, two of which had to be stacked near the edge of the breadoard. Finally, we connected the OSEMs following the canonical order

LL -> UR-> UL

LR -> SD

But found that UR was reading -14000 counts. So, we did a quick swap of the UR and UL sensors and verified that the OSEM itself is working, just in a different channel... So it's time to debug the electronics (probably PR2 Sat Amp?)...

PR2 Sat Amp preliminary investigation:

• The UR channel (CH1 or CH4, on PR2 Sat Amp)  gives negative value as soon as an OSEM is connected.
• Without anything connected, the channel reports the usual 0V output.
• With the PDA inputs of PR2 Sat Amp shorted, we again see 0V output.
• So it seems like when non-zero photodiode current goes, the circuit sees a reversal of gain polarity and the gain is roughly half in magnitude as the correct one.

• Started debugging D1002818 / S2100737 (8:30PM)
• Confirmed the issue of the negative output of the UR sensor with the dummy OSEM connected at the air side of the ITMY chamber. Both PD Out and PD Mon have negative outputs.
• The same issue remains when the dummy OSEM box is connected to the chassis with a short DB25M/F cable at the rack.
• Started debugging the setup at the workbench.
  • CH1 TIA Output=-3.0V / CH2 (in question) TIA Output =-2.7V => No Problem
  • CH1 Whitening Out=+3.0V / CH2 Whitening Out=-1.4V => Problem
  • Resolder the components around whitening CH2 => no change
  • Remove AD822 and replace with a new one => CH2 Whitening OUt = +2.7V ==> Problem solved
  • PD1~3 channels of the left and right PCBs tested with the OSEM box ==> nearly +3V/-3V differential output (All Clear)
  • Chassis closing
• Chassis restored in Rack 1Y1 and the normal output with the dummy OSEM box confirmed
• Mission Completed (9:30PM)
• Elog finished (9:40PM)
• Case closed

[Paco]

Thanks to Koji's hotfix on the PR2 SatAmp box last evening, this morning I was able to finish the OSEM installation for PR2. PR2 is now fully damped. Then, I realized that with the extreme rebalancing done in ITMX chamber, LO1 needed to be reinstalled, so I proceeded to do that. I verified all the degrees of freedom remained damped.

I think all SOS are nominally damped, so we are 90% done with suspension installation!

SUSPENSION STATUS UPDATED HERE

All green! Great work, Team!

AS1, PR2 and PR3 are set to o go through a free swinging test at 3 am. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

Jordan, Chub

Today, Chub and I removed TP1 and the failed manual gate valve off of the pumping spool.

First, P2 needed to be vented in order to remove TP1. TP1 has a purge valve on the side of the pump which we slowly opened bringing the P2 volume up to atmosphere. Although, this was not vented using the dry air/N2, using this purge valve eliminated the need to vent the RGA volume.

Then we disconnected TP1 foreline, removed TP1+8" flange reducer, then the gate valve. All of the removed hardware looked good, so no need to replace bolts/nuts, only needs new gaskets. TP1 and the failed valve are sitting on a cart wrapped in foil next to the pumping station.

I've summarized the optomechanics configuration for the in-vacuum aux small optics

It's not obvious here but the post for POP_SM4 is the stack of BA2V, Newport 9953, PLS-T238, LMR1V. The mirror is a CM254-750-E03 curved mirror. This should go on the suspension base. I hope I did not make a mistake there...

git repo: git@git.ligo.org:tega-edo/charmirrormap.git

The analysis code takes in a set of raw images, 10 in our case,  for each mirror and calculates the zernike aberration coefficients for each image, then takes their average. This average value is used to reconstruct the mirror height map.  Finally, the residual error between the reconstructed image and the raw data is calculated.

We repeat the analysis for different field of views (FoV) namely 10mm, 20mm, 30mm, 40mm and 46.5mm and save the results in the output folder of the repo.

The analysis output for a 10mm FoV aperture at the mirror center is shown in the attachement. These three images show the input data, the reconstructed mirror surface map and the residual error.

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the PR2 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/PR2 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks. I chose to not type out the matrix values now. One can find them in teh repo links above.

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the PR3 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/PR3 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks. I chose to not type out the matrix values now. One can find them in teh repo links above.

We still did not get a good AS1 free swinging spectrum. It seems the Side OSEM is reporting coupling to too many DOFs and some extra resonances than we expect. So we did not upload the new input matrix calculated from this test. I'm attaching teh peak fitting (attachment 1) and the diagonalization attempt (attachment 2) to give some idea of what happened. Note how different this fre swinging spectrum looks from the other optics. Given that Yehonathan also felt that somthing might be off with this optic, we need to reevaluate if the suspension has wire not aligned in grove, or it is imbalanced or something else if touching it still.

Here is more detail of the POP_SM4 mount assembly.

It's a combination of BA2V + PLS-T238 + BA1V + TR-1.5 + LMR1V + Mirror: CM254-750-E03
Between BA1V and PLS-T238, we have to do a washer action to fix the post (8-32) with a 1/4-20 slot. Maybe we can use a 1" post shim from thorlabs/newport.
Otherwise, we should be able to fasten the other joints with silver-plated screws we already have/ordered.

I think TR-1.5 (and a shim) has not been given to Jordan for C&B. I'll take a look at these.

Asked Jordan to clean 2x 1.5" posts (0.5 dia) and a washer with 1" dia.

Jordan, Chub

Chub and I installed the new manual gate valve (Nor-Cal GVM-6002-CF-K79) and reinstalled TP1. The new gate valave was placed with the sealing side towards the main 40m volume, then TP1 was installed on top and the foreline reattched to TP1.

This valve has a hard stop in the actuator to prevent over torquing.

Received the new 1100VA APC UPS today and placed it at the bottom of the valve rack.  I'd connected the battery and plugged the unit into the AC outlet, but did not turn it on due to the power outage this weekend.

Finally got the SIMPLANT damping to work following Rana's suggestion to try damping one DoF at a time, woo-hoo!

At first, things didn't look good even when we only focus on the POS DoF. I then noticed that the input value (X1:SUS-OPT_PLANT_TM_RESP_1_1_IN1) to the plant was always zero. This was odd bcos it meant the control signal was not making its way to the plant. So I decided to look at the sensor data

(X1:SUS-OPT_PLANT_COIL_IN_UL_OUTPUT, X1:SUS-OPT_PLANT_COIL_IN_UR_OUTPUT, X1:SUS-OPT_PLANT_COIL_IN_LR_OUTPUT, X1:SUS-OPT_PLANT_COIL_IN_LL_OUTPUT)

that adds up via the C2DOF matrix to give the POS DoF and I noticed that these interior nodes can take on large values but always sum up to zero because the pair (UL, LL) was always the negative of (UR,LR). These things should have the same sign, at least in our case where only the POS DoF is excited, so I tracked the issue back to the alternating (-,+,-,+,-) convention for the gains

(X1:SUS-OPT_CTRL_ULCOIL_GAIN, X1:SUS-OPT_CTRL_URCOIL_GAIN, X1:SUS-OPT_CTRL_LRCOIL_GAIN, X1:SUS-OPT_CTRL_LLCOIL_GAIN, X1:SUS-OPT_CTRL_SDCOIL_GAIN)

of the Coil Output filters used in the real system, which we adopted in the hopes that all was well. Anyways, I changed them all back to +1. This also means that we need to change the sign of the gain for the SIDE filter, which I have done also (and check that it damps OK). I decided to reduce the magnitude of the SIDE damping from 1 to 0.1 so that we can see the residuals since the value of -1 quickly sends the error to zero.  I also increased the gain magnitude for the other DoF to 4.

When looking at the plot remember that the values actually represent counts with a scaling of 2^15 (or 32768) from the ADC. I switched back to the original filters on FM1 (e.g. pit_pit ) without damping coefficients present in the FM2 filter (e.g. pit_pit_damp).

FYI, Rana used the ETMY suspension MEDM screen to illustrate the working of the single suspension to me and changed maybe POS and PITCH gains while doing so.

Also, the Medify purifier 'replace filter' indicator issue occurred bcos the moonlight button should have been pressed for 3 seconds to reset the 'replace filter' indicator after filter replacement.

Bought dish soap and scrub sponges today and placed them under the sink with the other dish supplies.