Late entry 4-16 (Wednesday) activities: - The previously received, poorly packaged Inficon gauge has been tested, and found functional. These tests continue, and also the HAM1 vacuum interlock gauge will be installed soon - The BSC8 Annulus Ion Pump - after some aux cart pumping - is now able to hold the annulus pressure, at the mid- E-6 Torr region - The rough pumpdown of the corner has started at 16:20, at the OMC turbo station, with a pair of ISP-1000 mobile pumping carts. In 4 hours, ~185 Torr was achieved, which means 1930 l/s effective pumping speed, which well corresponds with the 2000 l/s theoretical speed of the pumps - The rough pumping still needs to be terminated in the end of the days, and so it was at 20:20 - All the turbo stations have been prepared for the HV pumping at the corner
Closes FAMIS26039 , last checked in alog83802
Most of the HAMs looks more elevated than last time, due to the vent activities.
The BSCs look the same as when they were last checked.
TITLE: 04/17 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
SEI_ENV state: MAINTENANCE
Wind: 5mph Gusts, 3mph 3min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.20 μm/s
QUICK SUMMARY:
VAC team have been Pumping down the corner station volume for 15 hours now and H0:VAC-LX_Y2_PT180_MOD1_PRESS_TORR channel is reporting that we are below 200 torr in BSC8 chamber.
Expected work today:
For each ADC a user model uses the RCG generates an ADC MEDM showing the raw counts for only those channels the model connects to. In order to make this MEDM more useful, for each channel the RCG attempts to find a named part in the simulink mdl and adds that name to the MEDM.
If the first simulink part found when traversing the model does not have a name (e.g. is a summation, gain, multiplier, etc.) currently the RCG leaves this channel off the MEDM. Future RCG versions will fix this by adding generic ADC names, but in the mean time we are taking the vent RCG upgrade as an opportunity to install named EPICS_OUTPUT parts where needed. Ideally the subsystem authors would give these parts descriptive names, but failing that we will give them generic ADC_x_y type names.
Jim has done this for the ISI HAM models, so when we restarted h1isiham2 and h1isiham5 on monday those models' ADC MEDMs were corrected. The attachment shows the ADC MEDMs for h1isiham2 (full) compared with h1isiham3 (partial).
TITLE: 04/17 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
The Vacuum team has started the Pump Down !
The SPI team has components on the table and are currently in an optomization stage.
I think Jim still has more work to do on HAM1.
Joe doing update of installed pydarm code.
At 21:38 UTC the water level sensor for the fire tank was restarted by Eric because it was reading as full but was not.
21:48 UTC the Water tank sensor was restarted to make the Water level sensor read correctly.
LOG:
Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
---|---|---|---|---|---|---|
14:53 | FAC | Randy | LVEA | N | Prepping for work | 14:08 |
14:54 | FAC | Mitchel & Randy, Jim, Corey | LVEA | N | Craning parts | 18:54 |
14:54 | FAC | Kim & Nellie | LVEA | N | Technical Cleaning | 16:54 |
15:19 | VAC | Jordan | LVEA | n | Purge Air checks | 15:47 |
16:39 | VAC | Janos | LVEA | N | Walkin the LVEA to get caught up on the VAC Status | 16:54 |
16:47 | VAC | Jordan | LVEA | N | Check Turbo pump on BSC7 & Prep Turbos for Pump Down | 18:57 |
16:52 | IAS | Jason | LVEA | N | Setting up Surveying Equipmentr | 19:07 |
16:53 | PSL | Ryan S | PSL | YES | PSL checks and SPI work | 19:59 |
16:53 | IAS | Ryan C | LVEA | N | Surveying with jason | 17:41 |
17:02 | VAC | Travis | LVEA | N | LVEA ouput arm with HAM1 flanges | 17:08 |
17:04 | SPI | Josh | Optics Lab | yes | Getting parts for PSL SPI work | 17:34 |
17:28 | ISI | Betsy | LVEA | N | Checking on HAM1 crew | 18:07 |
17:31 | SPI | Sina & Josh | PSL | Yes | Installing SPI optics in PSL | 19:58 |
17:45 | FAC | Tyler | YARM backside | n | Check well line | 18:35 |
17:46 | SPI | Keita | OpticsLab | YES | Helping with PSL SPI work | 20:26 |
17:58 | SPI | Jeff | Optics Lab | yes | working on SPI optics | 18:31 |
18:02 | HAM1 | Sheila | LVEA HAM6 | N | Looking for parts | 18:11 |
18:16 | VAC | Travis | LVEA | n | Looking for Marristat bags | 18:26 |
19:30 | PCAL | Tony | PCAL Lab | Yes | transfer standard Measurement config change | 19:37 |
19:48 | HAM1 | Betsy & Travis | LVEA | N | HAM1 feed throughs | 21:22 |
19:52 | HAM1 | Mitchel & Randy | LVEA HAM1 | N | Installing HAM1 ISI accessories, Mitchell out Early | 21:25 |
20:01 | SEI | Jim | LVEA | N | Plugging in HAM1 Electronics | 22:47 |
20:02 | Vac | Janos & Jordan | LVEA | N | Prep turbo pumps for pump down | 20:34 |
20:24 | EE | Fil | LVEA | N | Workign on Feed Through with Betsy & Travis | 21:27 |
20:33 | SEI | Jennie, Edgor, Sina | LVEA | N | Taking a look at the HAM1 Work | 20:50 |
20:35 | SPI | Josh | Optics Lab & PSL | YES | Optics work for SPI system | 21:00 |
20:46 | PSL | Ryan S, Sina, Josh | PSL | Yes | SPI pickoff beam path from PSL | 00:01 |
20:59 | Safety | Richard | LVEA | N | Safety Checks | 21:10 |
21:01 | FAC | Tyler | LVEA | N | Checking on HVAC in Southbay | 21:09 |
21:09 | SUS | Ryan C & Rahul | LVEA HAM6 | N | Dropping off SUS & Optics | 21:14 |
21:10 | IAS | Jason | LVEA | N | Aligning | 21:58 |
21:16 | IAS | Ryan C | LVEA | N | Surveying | 21:58 |
21:29 | VAC | Jordan | Mid X&Y | N | Cap. Inventory | 21:51 |
21:32 | FAC | Eric | Water Tank | N | Resetting water Tank water level sensor | 22:17 |
21:52 | VAC | Jordan | LVEA | N | Turbo pump checks | 22:39 |
22:50 | Vac | Janos & Jordan | LVEA | N | Starting Pump Down | 01:50 |
23:36 | IAS | Jason | LVEA | N | Unplugging battery | 23:40 |
23:42 | Pcal | Tony | PCAL Lab | Yes | Checking PCAL config | 23:47 |
J. Kissel scribing for S. Koehlenbeck, J. Oberling, R. Short, J. Freed ECR E2400083 IIET 30642 WP 12453 Another quick summary aLOG at the end of the day, with more details to come: - With the power in the ALS/SQZ pick-off path to 10 [mW] for beam profiling, - Installed a two lens system to handle the unexpectedly different beam profile of the ALS/SQZ pick-off path - Remeasured the resulting mode after the two lens system, and we're happy enough. We're gunna call them SPI-L1 and SPI-L2. - Installed steering mirrors SPI-M1 and SPI-M2. - Rotated ALS-HWP2 to increase the s-pol light in the ALS/SQZ/SPI path to return the power transmitted through SPI-BS1 going to the ALS/SQZ fiber collimator back to 50.5 [mW]. This set the SPI path to 186 [mW] with the PMC TRANS measured at 103.5 [W]. The ALS_EXTERNAL PD in transmission of ALS-M9 measured 31 [mW] ***. - Installed SPI-HWP1 and SPI-PBS01 - Measured the power at each port of SPI-PBS01, with the intent to optimize the SPI-HWP1 position to yield maximum p-pol transmission through SPI-PBS01. *** We expect this is lower than the goal of ~45 [mW] (from LHO:83927) because we've not yet re-aligned the ALS/SQZ fiber collimator path after the install of the SPI-BS1, which translates the beam a bit due to the thickness of the beam splitter. We intend to get back to this once we're happy with the SPI path.
Small correction to above is after installing SPI-HWP1 and SPI-PBS01, we adjusted HWP1 to have 20mW in transmission of PBS1 (not maximum quite yet) to start alignment into the fiber. Using the two steering mirrors downstream of PBS1 and the collimating lens in front of the fiber, Sina maximized the transmission as measured with the output of the fiber on a spare PD. We then took power measurements of the input and output of the fiber:
This is a good start, but with a target ratio of >80%, there's still more work to be done here improving the beam into the fiber collimator. Out current mode-matching solution claims we should have 95% mode overlap into the fiber, so hopefully the issue is alignment, but it's entirely possible we'll revisit the mode-matching to see if improvements can be made there too.
The attached photo represents the optical layout as it stands as of where we stopped today, with the new SPI fiber in blue on the left (north) side of the table.
Re-post of Ryan's picture at the end of day 2, labeled with the almost entirely complete SPI pick-off path. Critically here, this shows the PSL row/column grid, confirming that this whole ECR E1900246 ALS pick-off path is 2 rows "higher" in +Y than is indicated on the current version of the as built PSL drawing D1300348-v8.
Ryan grabbed another picture I attach here. This shows the ALS pick-off path on this day in order to support the identification that the beamline between ALS-M1, through the faraday ALS-FI1 and ALS-L1, etc stopping at ALS-M2 (not pictured) is on row 25 of the PSL table *not* row 23 as drawn in D1300348-v8. I attach both the raw picture and my labeled version. So, ya, ALS-M1 should have its HR surface centered on Row 25, Col 117. Note, the grid in the picture is labeling bolt holes. Because the optical elements are all ~4 inches above the table, the beams appear offset from the way they travel on along the grid given that the photo was taken at a bit of an angle from vertical. May the future updater of D1300348 bear this in mind.
Sheila, Oli, Jeff, Erik, Edgard, Brian
While looking at the pointing drift over the course of the vent for SR3, Sheila and I noticed a jump in the DAMP_P_INMON channel before vs after the SR3 model restart that was done yesterday (83906) (attachment1). We looked around trying to trace where the discrepancy started until we finally noticed that the 32 coming out of DITHER P was entering DRIVEALIGN as L (attachment2). This was confirmed as the discrepancy when we trended the DRIVEALIGN_L and DRIVEALIGN_P channels and confirmed that before the model restart, DRIVEALIGN_L was (correctly) 0 and DRIVEALIGN_P was (correctly) 32, but after the model restart they had been swapped (bottom middle of attachment1).
Looking at the 2nd and 3rd Simulink model screenshots that Jeff had uploaded in 83911, we see that the ADDFF block takes in LPY in the wrong order - as FF_P_In, FF_Y_In, FF_L_In, and then sends it back out in the wrong order as well - as PITCH_Out, YAW_Out, LONG_Out
.
I've corrected these mistakes (attachment3, attachment4) and recompiled the PR3 and SR3 models, and Erik was available to restart both models for us. Everything looks good now! The discrepencies with DAMP_P_INMON and the Left and Right COILOUTs have been resolved.
Changes in model /opt/rtcds/userapps/trunk/sus/common/models/SIXOSEM_T_STAGE_MASTER_W_EST.mdl committed to svn as r31287.
J. Kissel scribing for S. Koehlenbeck, R. Short, J. Oberling, and J. Freed ECR E2400083 IIET 30642 WP 12453 During yesterday's initial work installing the SPI pick-off path (LHO:83933), the first optic placed was SPI-BS1, the 80R/20T power beam-splitter that reflects most of the s-pol light towards the new SPI path. The pick-off is to eventually be sent into a SuK fiber collimator (60FC-SF-4-A6.2S-03), so we wanted to validate the beam profile / mode shape of this reflected beam. The without changing any power in the ALS/SQZ/SPI pick-off path, the power now reflected from newly installed SPI-BS1 measured ~40 [mW] (see LHO:83946). This is too much for the WinCam beam profiler, so they used ALS-HWP2 to rotate the polarization going into ALS-PBS01, and thus reduced the reflected s-pol light in this ALS/SQZ/SPI pick-off path to ~10 [mW]. That necessarily means there's a little more of the ~2 [W] p-pol light transmitted and going toward the HAM1 light pipe, so they placed a temporary beam dump after ALS-M2 so as to not have to think about it. The they set up a WinCam head on a rail and gathered the beam profile. With the WinCam analysis software on a computer stuck in the PSL, they simply gathered the profile information which I report here: # Distance[cm] Radius[um] Radius[um] X Y 0.0 680.5 717 17.78 465 504 25.4 389 428.5 30.48 346.5 368 38.1 281.5 300.5 where "X" is parallel to the table, and "Y" is orthogonal to the table. The "0.0" position in this measurement is the "front" of the rail (the right most position as pictured in the attachment), which is Column 159 of the PSL grid. SPI-BS1 has the center of its reflective surface is set in +/- X position in Column 149 (within the existing ALS-PBS01 to ALS-M9 beam line). It's +/- Y position is set to create a reflected beam line along Row 30 of the grid, and the WinCam head and rail are centered in +/- Y on that Row to capture that beam. Using this profile measurement, we find it to be quite different than expected from when this path was installed circa 2019 (see e.g. LHO:52381, LHO:52292, LHO:51610). Jason shared his mode matching solution from LHO:52292 with us prior to this week, and I've posted it as a comment to that aLOG, see LHO:83957. We think we can trace the issue down to an error in the as-build drawing for the PSL: - the whole beam path running in the +/-X direction from ALS-M1 to ALS-M2 is diagrammed to be on row 23 -- however, we find in reality, the path lies on row 25. That's 2 inches more between the (unlabeld) pick-off beam splitter just prior to ALS-M1 and ALS-M1 itself. Easily enough to distort a mode matching simulation. - Jason confirms that he used the *drawing* to design the lens telescope for this ALS/SQZ fiber distribution pick-off path. More on this as we work through a lens solution for the SPI path. As of this entry, we elect to NOT create a new solution for the whole ALS/SQZ fiber distribution pick-off i.e. we *won't* adjust ALS-L1 or ALS-L5 in order to fix the true problem. But, we report what we found in the event that a case is better made to help mode matching and aligning into the ALS/SQZ fiber distribution pick-off easier -- as we have verbal confirmation that it was quite a pain. For the record the fiber collimator used in the ALS/SQZ distribution pick-off is a Thor Labs F220 APC-1064.
Just a quick trend of the SM1PD1A EXTERNAL PD in transmission of ALS-M9 after they throttled the s-pol power in the ALS/SQZ/SPI path to ~10 [mW]. In that trend, you can see the different in "lights on" vs. "lights off" highlighted with the magenta vertical lines. Note, as you can see in the picture, the reflection of ALS-M9 is dumped so as to not have to think about how much power is or is not going into the ALS/SQZ fiber distribution collimator (ALS-FC2), so the INTERNAL monitor PD that's in the distribution chassis itself is "correctly" unexpectedly reading nothing, so I don't show it.
Correction to the last sentence of the main entry -- the ALS/SQZ fiber collimator is *not* an, but instead a Thorlabs Fiber Port PAF2-5A, pictured well in FinalInstall_ALSfiber.jpg from LHO:83989. I had incorrectly assumed that this collimator would be a copy of ALS-FC1, which *is* listed in E1300483 as an F220 APC-1064.
In the attachment you will find the fit with JAMMT to the measured beam profile data with offset correction:
Distance (cm) | Radius horiz. (um) | Radius vert. (um) |
17.46 | 680.5 | 717 |
35.24 | 465 | 504 |
42.86 | 389 | 428.5 |
47.94 | 346.5 | 368 |
55.56 | 281.5 | 300.5 |
Matt, Elenna, Camilla
All individual optics removed from HAM1 have been inspected, cleaned and if needed swapped. Progress alogs: 83875, 83858.
The optics are in pans 1, 2 and 3. We still need to inspect the mirrors on the pericope and might swap more black glass beamdumps to DLC coated SS, but otherwise we are ready to install back into HAM1. Optics that were changed are noted below, this has been updated in the D1000313 googlesheet. All removed optics are stored with the other optics in the staging building.
Optic
|
Original
|
New
|
Note
|
M1
|
BS50%1064
E1000671-02
S/N 052
|
BS50%1064
E1000671-02
Note below *
|
Original Optic had specks on the center that couldn't be removed with FC
|
M10
|
HR1064HT532 E1000669
S/N 014
|
HR1064HT532
E1000669-v1
S/N 043
|
Original Optic had cluster of specks on the center that couldn't be removed with FC
|
M12
|
BS95%1064
E1000871-02
S/N 004
|
BS90%1064
E040512-B3
IO820-05
|
Changed 95/5 to 90/10 BS
|
M15
|
HR1064
E1100048
S/N 2.0-0990
|
BS50%1064
E040512-B1
S/N IO826-08
|
Swapped from HR1064 to 50/50BS, changed handedness, moved picos.
First BS optic we tried to use in 83858 had 1" thin line across, so swapped again.
|
* The M1 BS E1000671-02 had no S/N but the box was labeled with Coating Run 515074 & 315079 and datasheet. We scrubbed the pencil mark off the barrel so it's barely visible, but the coated side was above the writing, see photo attached.
Janos - 9:50, LVEA The X-manifold is valved out from the main volume both sides, the main turbo is pumping on it. On the X-manifold I slightly opened up the suspicious blanked-off small Varian gate valve (see photo), to find out if it is opened or closed. I moved very slowly the hand-actuator, and the pressure spiked up to the E-5s, then it immediately started to go down, now it is already at ~3E-7 (the initial value was ~1E-7). So, the valve was closed and blanked off, therefore it wasn't stored appropriately, thus at the next opportunity (when the X-manifold will be vented), it will be removed, and blanked off.
The handler of this valve was torqued, and the pressure in the X-manifold fell to 8.14E-8 Torr, and it is seemingly stabilized. Before poking with this valve, the pressure was 1.04E-7 Torr (and still rising), so there was indeed a leak from this valve to the system, as this torquing means ~20% reduce in gas load. We do a comprehensive leak check on the X-manifold during the rest of the week, so this valve with all adjacent flanges will be bagged and leak checked. We are also considering putting an adapter on the valve instead of a blank, and pump it down, so the lower pressure in the outer side of the valve could help, if there is still some communication between the valve and the system - but of course, it depends on the result of the leak check. Finally, the handler of this valve was LOTO-d - it was simply taken off, so there will be no accidental moving of this valve anymore.
Edgard, Oli
We took measurements to get the above-resonance OSEM response of the PR3 and SR3 suspensions to characterize the gaines. This is a follow up to the in vacuum measurements on 80863, and to the estimated calibrations from 83605.
For PR3, the measurements were taken with
- all of the M1 damping loops at a gain of -0.2 (instead of the nominal -1).
-The coil driver filter in state 1 (similar to the measurements that Jeff took).
- The ISI state was ISOLATED, but HEPI is locked, so we circumvented guardian by sliding off the Isolation Gain on HEPI. This should not affect the measurements for the OSEM calibration.
The results are saved in:
/ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/PR3/Common/Data/
2025-04-15_1431_H1ISIHAM2_ST1_WhiteNoise_PR3SusPoint_L_0p02to50Hz.xml 2025-04-15_1431_H1ISIHAM2_ST1_WhiteNoise_PR3SusPoint_T_0p02to50Hz.xml 2025-04-15_1431_H1ISIHAM2_ST1_WhiteNoise_PR3SusPoint_V_0p02to50Hz.xml
The similarly named _tf.txt files are stored in the same folder, and they export the measured M1 transfer functions using the [ L T V R P Y ] order.
SR3 Measurements:
I had a hard time trying to take data at first (no matter the excitation amplitude we were seeing no movement on the ISI sensors), and we figured out that it was because the SUSPOINT matrix for HAM5 ISI had never been populated! We found the correct matrix values in $(USERAPPS)/isc/common/projections/ISI2SUS_projection_file.mat as ISI2SUSprojections.h1.sr3.EUL2CART, and used /ligo/svncommon/SeiSVN/seismic/Common/MatlabTools/fill_matrix_values.m to fill them in. Then I was able to run the transfer functions.
Data files can be found at /ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/SR3/Common/Data/2025-04-15_2100_H1ISIHAM5_ST1_WhiteNoise_SR3SusPoint_{L,T,V}_0p02to50Hz.xml, and have been committed to svn as r12227.
This morning we decided to do the rest of the DOFs for the SUSPOINT to M1 measurements of PR3 and SR3.
For SR3:
Same setup as before:
Data files can be found at /ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/SR3/Common/Data/2025-04-15_2100_H1ISIHAM5_ST1_WhiteNoise_SR3SusPoint_{R,P,Y}_0p02to50Hz.xml, and have been committed to svn as r12232.
For PR3:
Same setup as before:
Data files can be found at /ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/PR3/Common/Data/2025-04-15_1431_H1ISIHAM5_ST1_WhiteNoise_SR3SusPoint_{R,P,Y}_0p02to50Hz.xml, and have been committed to svn as r12249.
Back in August 2023 the damping gains for SR3 were reduced from -1 down(up?) to -0.5 to help with noise in DARM (72130). Since that change, we had never taken a set of transfer functions with the damping loops on with these new gains, so today I took those. The resulting transfer functions don't show too much damping, which is expected.
The data can be found in ../HLTS/H1/SR3/SAGM1/Data/2025-04-15_2000_H1SUSSR3_M1_WhiteNoise_{L,T,V,R,P,Y}_0p01to50Hz.xml, and has been committed to svn as r12228.
The results can be found in ../HLTS/H1/SR3/SAGM1/Results/ as 2025-04-15_2000_H1SUSSR3_M1_ALL_TFs.pdf and 2025-04-15_2000_H1SUSSR3_M1.mat, and have been committed to the svn as r12229.
Linking analysis pdf showing cross coupling between all DOFs
Also adding a comparison between this measurement and the last time that we took damped transfer functions since those previous measurements would have been taken with a different set of damping gains.
The last time a damped measurement was taken was back in 2015, and those transfer functions look a lot different than the model and this recent measurement, so I also looked at the next previous damped measurement, from 2014. This one was in phase 2b, so not in chamber, but here at least we see that these damped measurements match up pretty well both with the model and with the recent measurement.
This PDF along with a zoomed in version of some of the plots can be found at /ligo/svncommon/SusSVN/sus/trunk/HLTS/Common/Data/ as
allhltss_DampingOnComparison_H1SUSSR3_M1_Apr25vsFeb15vsMar14_ALL_TFs.pdf
allhltss_DampingOnComparison_H1SUSSR3_M1_Apr25vsFeb15vsMar14_ALL_ZOOMED_TFs.pdf
and have been committed as r12251.
J. Kissel, S. Koehlenbeck, J. Oberling, R. Short, J. Freed ECR E2400083 IIET 30642 WP 12453 After this morning's kerfuffle / belated power-outage recovery with the PSL HVAC system was resolved, Sina, Ryan, and Josh began the procedure we're walking thru outlined in Section 1 of T2500024. We're keeping running notes on the fly at the bottom of the google-doc for now. In summary here, with more details to come, we got as far as - Clearing out some old IO equipment that unused and in the way of the SPI pick-off path - Measuring the power around ALS-PBS01 - Installing the new ALS/SPI 80R/20T beam splitter - Measuring the beam profile along the future SPI path, in reflection of this 80R/20T beam splitter.
Among the first things we did was measure the power at various places along the ALS beam path to get a good starting point. For the ~2W beams we used an Ophir 20C-SH (datasheet says accuracy of +/- 3%) and for ~100 mW beams we used a S401C, (datasheet says accuracy of +/- 7%). For laser safety, we would unlock the PMC and shutter the laser while we were placing these power meters, so I also kept track of the PMC TRANS to scale our measurements by input power appropriately. We did NOT turn on the PMC's intensity stabilization servo (ISS), for no particular reason other than we forgot to turn it on for the first measurement, and then wanted to stay consistent. This meant that the PMC TRANS itself was slowly noise at that +0.5 [w] level, so my reported values below are "eyeball averages." So, not exactly a NIST-level precision/accuracy setup, but good enough for sanity checks. As such, I'm not going to bother report uncertainty in the numbers below. Here're the results (again, this is prior to doing anything to the path). Times of measurements are all for 2025-04-15, and in UTC, such that trends of other PDs may be captured if need be. Location Power Meter [mW] PMC Trans [W] Time [UTC] (1) Going in to ALS-HWP2 2060 103.2 21:39 # expected: 2000 [mW]; good! (between ALS-L1 and ALS-HWP2) (2) p-pol in trans of ALS-PBS01 1970 102.8 22:17 # expected: 1950 [mW]; good! (between ALS-M2 and ALS-L2) (3) s-pol in refl of ALS-PBS01 49.4 103.2 21:44 # expected: 50 [mW]; good! (between ALS-L1 and ALS-M9) (4) s-pol in refl of ALS-M9 47.7 103.0 21:48 # 44.9 [mW] reported by ALS-C_FIBR_EXTERNAL_DC_POWERMON, which is in trans of ALS-M9 at this time; good! (between ALS-M9 and ALS-FC2) All of these powers match expectation quite exquisitely. My guess for the inconsistency of (4) with the EXTERNAL monitor PD is that the beam splitter ratio of ALS-M9 programmed into the beckhoff calibration of the PD's channel is a bit off, but this can be cross-checked later. We then installed SPI-BS1 (the 80R/20T BS), and cross-checked the reflectivity reported in LH0:83863. Location Power Meter [mW] PMC Trans [W] Time [UTC] (5) s-pol in refl of SPI-BS1 37.7 102.4 22:22 The PMC power is lower between (3) and (5), the input to the SPI-BS1 is different, so we need to scale the measurement a bit, Input Power to SPI-BS1 = 49.4 [mW] * (103.2 / 102.4) = 48.81 [mW] REFL power from SPI-BS1 = 37.7 [mW] Fractional reflection = 37.7 [mW] / 48.81 [mW] = 0.772 = 77% (from LHO:83863) = 77%. Thus, our results today are consistent with what Josh and Keita measured in the optics lab.
Pictures from the work on 2025-04-15. The first three attachments are without labels, just in case the pics are needed for something else in the future. The diagram we were working with (from the SPI ECR) is also attached here for convenience. The second three attachments *are* labeled, so I'll describe what happened using those. 20250415_some_optics_removed_labeled.jpg - This is (mostly) the how the team started the day: with the area where the SPI pick-off path is intended to go full of un-diagrammed spare/unused stuff. I highlight red circles everything that was removed in this first attachment. Additionally, before the picture was taken, ALS-M8 and ALS-FC1 were removed and the temporary large vertical beam block was installed. 20259415_all_optics_removed_labeled.jpg - This is the "after" all components cleared picture, and the table layout during the power measurements. As you can imagine, because of the lens tube on the SM1PD1A, there was no room between the PD and ALS-M9 to insert a power meter to measure the transmitted light thru ALS-M9. As such, we can't validate the beam-splitting ratio of that optic. Ah well. 20250415_end_day_1_labeled.jpg - This is how we left yesterday: We SPI-BS1 installed in its permanent location. Downstream, we sent the reflected beam into a WinCam head such that we could profile the beam incoming to the SPI path -- and assess whether we need lenses in order to adjust the beam size to match our fiber collimator. While we definitely saw the expected change in power and alignment at ALS-FC2, we elected to restore the power and alignment later.
Jason O, Georgia M
This week we have been in the PSL installing a new fiber pick-off for the ALS and squeezer lasers. The old pick off is on transmission of the reference cavity while the new one is on the ALS bypass, after the PMC. Peter K started this work a month ago (alog 51610).
We currently have installed a mode matching lens (f=200mm f=150mm) between the beam splitter and the steering mirror, and achieved ~73% ~82% power transmission through the fiber so far.
We think we can get more light through the fiber by tweaking the mode matching lens position. We will need to go back into the PSL again to finish this work and feed the fiber and photodiode cable out to the rack.
Once the layout is finalised I'll update the psl table layout document (D1300348).
Modifications to the fiber distribution box are also ongoing.
J. Kissel for J. Oberling As we work through the history of the ALS pick-off path in order to augment it and create an SPI pick-off path within (ECR E2400083), Jason shared a screenshot of his beam-profile model from JAMMT when he suggested placement of ALS-L5 (the f=150 mm lens mentioned abov). I post it here for historical reference. For the record the fiber collimator used in the ALS/SQZ distribution pick-off is a Thor Labs F220 APC-1064.
So there is clarity here for future reference, I created that quick-and-dirty JamMT model from the as-built LHO PSL table layout in March 2024, not when the ALS pickoff was installed in October 2019.
Further, the SPI pickoff install team discovered that the as-built PSL table layout has had an error in the ALS beam path since the IO side of the PSL table was installed during aLIGO PSL installation in the 2012 timeframe. The beam line from ALS-M1 to ALS-M2 is misplaced on the as-built layout; the layout shows the beam line along table row 23 but in reality it is along table row 25, 2 inches further +Y (using the IFO coordinate axes) than the layout indicates. Corey took pictures of the PSL table in 2013 (D1301029) that show ALS-M1 in line with the 2nd ISS turning mirror, which is along table row 25. Because of this the distances shown on the JamMT model are too short by 2 inches, rendering the beam waist size and location results given by that model incorrect. In addition, the overall ALS path is longer by 4 inches than the as-built layout implies.
I will correct this when I update the PSL as-built layout after the SPI team is done.
Right! The mode-matching model that Georgia put together can be found in an other file in the ECR E1900246, specifically PMCtoFiberMM.png.