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Reports until 16:33, Wednesday 02 July 2025
LHO General
corey.gray@LIGO.ORG - posted 16:33, Wednesday 02 July 2025 (85498)
Wed DAY Ops Summary

TITLE: 07/02 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
INCOMING OPERATOR: Tony
SHIFT SUMMARY:

H1's been locked for almost 8hrs (where the initial locking in the morning was almost entirely automatic--except for SQZ work [by Sheila & Matt] to address the issues Oli noted during the OWL shift). 

Decent Observing time for most of the shift, but the last hour of the shift was peppered with PI24 ring-ups that dropped us out of Observing and dropped our range.  Matt made changes to the ETMy Ring Heater to hopefully address this issue.

LOG:

H1 TCS
matthewrichard.todd@LIGO.ORG - posted 16:13, Wednesday 02 July 2025 (85514)
ETMY Ring Heater Change

M. Todd, S. Dwyer, C. Gray, A. Sanchez


We decided to set the ETMY ring heater back to 1W, as we were seeing PI24 having repeated dramatic ring ups. We expect this to set our LG10 y-arm mode to sit at 10490Hz once thermalized (fingers crossed). There are quite a few peaks around this region as well, but hopefully we move far enough away from PI24.

Saved the changes in SDF

Images attached to this report
H1 SQZ
corey.gray@LIGO.ORG - posted 14:29, Wednesday 02 July 2025 (85510)
H1 SQZ Adjustment

After about a 5.5hr lock, noticed range slowly drifting down over several hours.  With H1 out of Observing, took the opportunity to touch up the Squeezer with:

  1. OPO Temperature Adjustment (see 1st image), followed by...
  2. running a SCAN_SQZANG_FDS (ran one of these at the t=1hr mark for this current lock); see 2nd image.
Images attached to this report
H1 PSL (ISC)
jennifer.wright@LIGO.ORG - posted 11:12, Wednesday 02 July 2025 - last comment - 11:05, Thursday 03 July 2025(85458)
Calibrating ISS QPD

Jennie W, Rahul

Yesterday we made some measurements to calibrate the spot size on the QPD as we scan the beam position across it.

We used a connector Fil made us to plug in the OT301 QPD amplifier into a DC power supply after checking it contained voltage regulators that could cope with a voltage between 12 and 19 V ( as the unit says it expects DC supply but the previous one we were using was AC with a 100mA current rating and was getting too hot so we assume that was the incorrect one). We hooked it up at 16V (this draws about 150mA of current). The QPD readout looks normal and does not have any of the strange sawtooth we saw with the original power cable.

 

We moved the M2MS beam measurement system out of the way of the translation stage.

To calibrate the QPD we need to change the lateral position of the M1 mirror and lens to change the yaw positioning on the QPD and measure the X and Y voltages from the QPD.

We need to check we are centred first. The QPD bullseye readout shows the beam is off a tiny bit in yaw but this was as good as we could get at centering the beam when we moved the QPD. All 8 PDs are reading about 4.6 V so this means the beam is well centred in the array plane.

We measure 11000 counts on the bullseye qpd readout at this M1 position.

 

Translation Stage inch

QPD X (mV

)

QPD Y (V)
4.13 239e-3 -1.77
4.14 252e-3 -1.84
4.15 2.34 -1.60
4.16 4.46 -1.17
4.17 4.26 -1.11
4.18 5.62 -835e-3
4.19 7.80 -600e-3
4.20 7.81 -321e-3
4.21 8.45 -222e-3
4.22 8.82 +70.6e-3

4.23

9.19

771e-3

4.24 9.28 1.12
4.25 9.37 1.88
4.26 9.36 2.36
4.27 9.37 2.38
4.28 9.44 2.71
4.29 9.47 3.10
4.30 9.50 3.41
4.31 9.49 3.35
4.32 9.51 3.72
4.33 9.55 4.27
4.34 9.58 4.55
4.35 9.62 4.86
4.36 9.66 5.44
4.37 9.65 5.31
4.38 9.63 5.60
4.39 9.69 5.75
4.40 9.69 6.00
4.41 9.70 6.15
4.42 9.70 6.16
4.43 9.71 6.33
4.44 9.71 6.50
4.45 9.72 6.72
4.46 9.74 7.09
4.47 9.73 6.87
4.48 9.74 7.40
4.49 9.75 7.46
4.50 9.74 7.46
4.51 9.76 7.75
4.52 9.74 7.67
4.53 9.73 7.82
4.54 9.74 7.96
4.55 9.73 8.08
4.56 9.72 8.33
4.57 9.71 8.43
4.58 9.70 8.50
     
4.13 448e-3 -1.98
4.12 -1.02 -2.34
4,11 -1.17 -2.14
4.10 -2.92 -2.43
4.09 -4.63 -3.30
4.08 -5.91 -3.18
4.07 -6.97 -3.40
4.06 -8.17 -4.24
4.05 -8.13 -4.28
4.04 -8.52 -4.47
4.03 -8.76 -4.77
4.02 -8.89 -5.27
4.01 -9.01 -5.45
4.0 -9.08 -5.44
3.99 -9.10 -5.85
3.98 -9.11 -5.91
3.97 -9.11 -5.93
3.96 -9.12 -6.16
3.95 -9.12 -6.18
3.94 -9.13 -6.34
3.93 -9.13 -6.49
3.92 -9.12 -6.49
3.91 -9.13 -6.61
3.90 -9.11 -6.55
3.89 -9.11 -6.70
3.88 -9.10 -6.46
4.13    
     

 

I plotted the data from lowest reading on the translation stage to highest and fitted the linear region using Calibrate_QPD.m which is attached.

Data is shown in attached pdf.

The slop of the linear region in V/inch is 112 V/inch. Which means to if the beam moved 8.93 e-3 inches on the QPD in yaw, the yaw readout would change by 1 Volt.

Images attached to this report
Non-image files attached to this report
Comments related to this report
jennifer.wright@LIGO.ORG - 15:35, Wednesday 02 July 2025 (85512)

I altered the code to plot in mm and the constant is 4.4 V/mm.

Images attached to this comment
jennifer.wright@LIGO.ORG - 11:05, Thursday 03 July 2025 (85531)

D'oh I read the scale on the translation stage wrong so the x readings are actually lower by a factor of 10.

This makes the slope 44.1 V/mm which is more in line with the 65.11 V/mm Mayank and Shiva found for the QPD calibration here.

Ours could be different because we have a slightly different beam size and we moved the QPD in its housing to centre it which could have changed X to Y coupling in the QPD readout.

This implies our beam diameter on the QPD is around 0.4mm which makes a lot more sense considering the diode is 3mm!

 

As a cross-check we used the QPD 'bullseye' readout unit and Rahul changed the translation stage in yaw and we measured the beam dropping from 10400 counts in the middle of the QPP to 100s of counts at the edges.

Translation Stage [inch] QPD Sum Counts
0.413 10400
0.365 500
0.413 10400
0.49 400

diode size ~ ((0.49-0.365)*0.0254*1000) = 3.175 mm.

Images attached to this comment
Non-image files attached to this comment
LHO VE (VE)
gerardo.moreno@LIGO.ORG - posted 10:46, Wednesday 02 July 2025 (85501)
Annulus Ion Pump for HAM3 Rails

(Jordan V., Gerardo M.)

HAM3 annulus ion pump (AIP) railed today around 7:00 am this morning.  We'll try to diagnose the system at the next opportunity.  After the pump railed there is no noted effect inside the main vacuum envelope.

The AIP body was replaced last on 2015, see aLOG entry here.

Images attached to this report
LHO VE
david.barker@LIGO.ORG - posted 10:39, Wednesday 02 July 2025 (85502)
Wed CP1 Fill

Wed Jul 02 10:13:04 2025 INFO: Fill completed in 13min 1secs

 

Images attached to this report
H1 SEI (SEI)
ryan.crouch@LIGO.ORG - posted 10:36, Wednesday 02 July 2025 (85408)
ISI CPS Noise Spectra Check - Weekly

FAMIS 26044, last checked in alog85153.

HAMs:

HAM4 has a new V3 line at the upper end of the frequency bandwith shown.

HAM7 V2 and V3 also appear a little louder just over 100 Hz.

HAM8s V3 line just over 100Hz has reduced by ~an order of magnitude.

BSCs:

ITMY_ST2 V2 has become a little noisier at high frequency.

BS_ST2 V3 has become a little noisier at high frequency.

ETMX_ST1 line at just under 60Hz has increased in both H1 and V3.

Non-image files attached to this report
LHO General
corey.gray@LIGO.ORG - posted 07:51, Wednesday 02 July 2025 - last comment - 14:51, Wednesday 02 July 2025(85496)
Wed DAY Ops Transition

TITLE: 07/02 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 15mph Gusts, 8mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.05 μm/s
QUICK SUMMARY:

Rough night continues after Maintenance Day with rung up violins and input alignment shift. 

Comments related to this report
corey.gray@LIGO.ORG - 08:50, Wednesday 02 July 2025 (85499)SUS

NOTE:  Well, after getting H1 back to 60W, the violins are not rung up and better than how they looked at the end of my shift yesterday.

(Sheila & Todd are now looking at the Squeezer & I returned H1 to be able to "Observe WITH Squeezing".)

ryan.crouch@LIGO.ORG - 14:51, Wednesday 02 July 2025 (85503)SUS

I noticed ETMX mode1 has been high ever since coming back from maintenance yesterday and we usually don't damp this mode. I took a high res spectra to confirm that it was this mode and not another close line causing this and it was so I tried to find some damping settings.

Nothing worked all that well, some tentative new settings are FM1+FM2+FM10 G=-50.

H1 General (ISC, SQZ, SUS)
oli.patane@LIGO.ORG - posted 00:16, Wednesday 02 July 2025 - last comment - 10:07, Wednesday 02 July 2025(85492)
Ops OWL Intervention: SDFs edition

H1 Manager called on me to help with a bunch of SDF diffs.

- Some ASC POP A offsets, which were accepted in safe earlier today (85490), so I went ahead and accepted them for Observe as well

- IMC PZT offset changes, which were made earlier when working on realigning the IMC (85476)

- ALSX camera offsets, which were changed earlier (85472)

- the SR3 and SRM dackill bypass times were lengthened temporarily for part of the work today, which I realize now should have been reverted oops need to fix when we're out of Observing tomorrow

- SQZ OPO servo's common board excitation had been left switched on (switch on the right from EXC A), so I just opened the switch

Images attached to this report
Comments related to this report
corey.gray@LIGO.ORG - 10:07, Wednesday 02 July 2025 (85500)

Reverted DAQ Kill Bypass times to their 1200 values (per Oli's note above).

Images attached to this comment
H1 SUS
filiberto.clara@LIGO.ORG - posted 12:33, Tuesday 01 July 2025 - last comment - 15:58, Wednesday 02 July 2025(85463)
Top Sat Amps Modified for PRM/PR3/SR3/SRM/BS

WP 12640
ECR E2400330
Drawing D0901284-v5
T2500232

Today we started upgrading the SUS Sat Amps per ECR E2400330. Modification improves the whitening stage to reduce ADC noise from 0.05 to 10 Hz. The following units were replaced with modified units:

Suspension Old New
PRM TOP S1100067 S1100168
PRM/PR3 S1000275 S1100173
PR3 S1100175 S1100183
     
BS TOP S1100090 S1000291
BS RT/SD  S1100155 S1100066
     
SR3 Top S1000296 S1000284
SR3/SRM S1100178 S1000290
SRM S1100136 S1100068

F. Clara, C. Gray,  J. Kissel, O. Patane, M.Pirello

Comments related to this report
jeffrey.kissel@LIGO.ORG - 13:48, Wednesday 02 July 2025 (85504)CDS
Here's the characterization data and fit results for S1100168, assigned to PRM M1's T1T2T3LF OSEMs (what Fil refers to as just "PRM TOP" above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
        plotresponse_S1100168_PRM_M1_T1T2T3LF_20250630.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
PRM      M1       S1100168         CH1                T1           0.0969 : 5.30   120.10        zpk([5.3],[0.0969],1,"n")
                                   CH2                T2           0.0950 : 5.20   120.25        zpk([5.2],[0.095],1,"n")
                                   CH3                T3           0.0950 : 5.18   120.25        zpk([5.18],[0.095],1,"n")
                                   CH4                LF           0.0940 : 5.15   120.00        zpk([5.15],[0.094],1,"n")

The attached plot and machine readable .txt file are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

Even though I've fit for the transimpedance gain, I've elected *not* to include a gain in the foton design string relative to "ideal," as there are more scale factors in play that determine the overall [(meters)/(ADC cts)] scale in the calibration of the OSEMs (LED light power, PD response, any cable loss, ADC channel gain, etc.). Determining this overall scale is better left to different methods, a la LHO:84548, which we (eventually) anticipate doing for all SUS with ECR E2400330 upgraded satamps.

Non-image files attached to this comment
jeffrey.kissel@LIGO.ORG - 14:05, Wednesday 02 July 2025 (85505)CDS
Here's the characterization data and fit results for  S1100173 , assigned to PRM/PR3 M1's RTSD/T1T2 OSEMs (what Fil refers to as just "PRM/PR3" above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
        plotresponse_S1100173_PRMPR3_M1_RTSDT1T2_20250630.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
PRMPR3   M1       S1100173         CH1                RT           0.0969 : 5.3    120.00        zpk([5.3],[0.0969],1,"n")
                                   CH2                SD           0.0955 : 5.22   120.00        zpk([5.22],[0.0955],1,"n")
                                   CH3                T1           0.0975 : 5.35   119.75        zpk([5.35],[0.0975],1,"n")
                                   CH4                T2           0.0975 : 5.33   120.25        zpk([5.33],[0.0975],1,"n")

The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

See above LHO:85504 comment as to why an account of the fit transimpedance was not included in the foton design string gain.
Non-image files attached to this comment
jeffrey.kissel@LIGO.ORG - 14:06, Wednesday 02 July 2025 (85506)CDS
Here's the characterization data and fit results for  S1100183 , assigned to PR3 M1's T3LFRTSD OSEMs (what Fil refers to as just "PR3" above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
        plotresponse_S1100183_PR3_M1_T3LFRTSD_20250630.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
PR3      M1       S1100183         CH1                T3           0.0950 : 5.19   120           zpk([5.19],[0.095],1,"n")
                                   CH2                LF           0.0945 : 5.17   120           zpk([5.17],[0.0945],1,"n")
                                   CH3                RT           0.0940 : 5.14   120           zpk([5.14],[0.094],1,"n")
                                   CH4                SD           0.0955 : 5.24   120           zpk([5.24],[0.0955],1,"n")

The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

See above LHO:85504 comment as to why an account of the fit transimpedance was not included in the foton design string gain.
Non-image files attached to this comment
jeffrey.kissel@LIGO.ORG - 14:11, Wednesday 02 July 2025 (85507)
Here's the characterization data and fit results for  S1000291 , assigned to BS M1's F1F2F3LF OSEMs (what Fil refers to as just "BS TOP" above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
        plotresponse_S1000291_BS_M1_F1F2F3LF_20250630.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
BS       M1       S1000291         CH1                F1           0.096 : 5.19    121.50        zpk([5.19],[0.096],1,"n")
                                   CH2                F2           0.096 : 5.23    120.75        zpk([5.23],[0.096],1,"n")
                                   CH3                F3           0.096 : 5.26    120.00        zpk([5.26],[0.096],1,"n")
                                   CH4                LF           0.095 : 5.2     120.00        zpk([5.2],[0.095],1,"n")

The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

See above LHO:85504 comment as to why an account of the fit transimpedance was not included in the foton design string gain.
Non-image files attached to this comment
jeffrey.kissel@LIGO.ORG - 14:18, Wednesday 02 July 2025 (85508)
Here's the characterization data and fit results for  S1100066 , assigned to BS M1's RTSDxxxx OSEMs (with the 2x "xx" representing the unused channels not connected to anything in-vacuum. Fil refers to this as just "BS RT/SD" above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
        plotresponse_S1100066_BS_M1_RTSDxxx_20250630.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
BS       M1       S1100066         CH1                RT           0.0960 : 5.19   121.50        zpk([5.19],[0.096],1,"n")
                                   CH2                SD           0.0940 : 5.11   120.75        zpk([5.11],[0.094],1,"n")
                                   CH3                xx           0.0935 : 5.12   120.25        zpk([5.12],[0.0935],1,"n")
                                   CH4                xx           0.0965 : 5.26   120.50        zpk([5.26],[0.0965],1,"n")

The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

See above LHO:85504 comment as to why an account of the fit transimpedance was not included in the foton design string gain.
Non-image files attached to this comment
jeffrey.kissel@LIGO.ORG - 14:22, Wednesday 02 July 2025 (85509)
Here's the characterization data and fit results for  S1000284 , assigned to SR3 M1's T1T2T3LF OSEMs (Fil refers to this as just "SR3 Top" above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
        plotresponse_S1000284_SR3_M1_T1T2T3LF_20250630.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
SR3      M1       S1000284         CH1                T1           0.0960 : 5.25   120.1         zpk([5.25],[0.096],1,"n")
                                   CH2                T2           0.0950 : 5.2    120.1         zpk([5.2],[0.095],1,"n")
                                   CH3                T3           0.0960 : 5.27   120.1         zpk([5.27],[0.096],1,"n")
                                   CH4                LF           0.0945 : 5.16   120.5         zpk([5.16],[0.0945],1,"n")

The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

See above LHO:85504 comment as to why an account of the fit transimpedance was not included in the foton design string gain.
Non-image files attached to this comment
jeffrey.kissel@LIGO.ORG - 14:30, Wednesday 02 July 2025 (85511)
Here's the characterization data and fit results for  S1000290 , assigned to SR3/SRM M1's RTSD/T1T2 OSEMs (Fil refers to this as just "SR3/SRM" above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
        plotresponse_S1000290_SR3SRM_M1_RTSDT1T2_20250630.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
SR3/SRM  M1       S1000290         CH1                RD           0.0955 : 5.21   120.1         zpk([5.21],[0.0955],1,"n")
                                   CH2                SD           0.0940 : 5.13   120.5         zpk([5.13],[0.094],1,"n")
                                   CH3                T1           0.0930 : 5.07   120.5         zpk([5.07],[0.093],1,"n")
                                   CH4                T2           0.0950 : 5.2    120.1         zpk([5.2],[0.095],1,"n")

The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

See above LHO:85504 comment as to why an account of the fit transimpedance was not included in the foton design string gain.
Non-image files attached to this comment
jeffrey.kissel@LIGO.ORG - 15:58, Wednesday 02 July 2025 (85513)CDS
Here's the characterization data and fit results for  S1100068 , assigned to SRM M1's T3LFRTSD OSEMs (Fil refers to this as just "SRM" above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100068_SRM_M1_T3LFRTSD_20250630.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
SRM      M1       S1100068         CH1                T3           0.094 : 5.14    120.10        zpk([5.14],[0.094],1,"n")
                                   CH2                LF           0.095 : 5.18    120.25        zpk([5.18],[0.095],1,"n")
                                   CH3                RT           0.096 : 5.23    120.75        zpk([5.23],[0.096],1,"n")
                                   CH4                SD           0.096 : 5.29    119.00        zpk([5.29],[0.096],1,"n")

The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

See above LHO:85504 comment as to why an account of the fit transimpedance was not included in the foton design string gain.
Non-image files attached to this comment
H1 General
anthony.sanchez@LIGO.ORG - posted 19:39, Monday 30 June 2025 - last comment - 16:58, Wednesday 02 July 2025(85447)
PCAL Lab TX module Maintenance complete

On Friday Jun 27th Francisco and I went to the the PCAL lab and did a PCAL TX module maintenance according to T1600436.
AOM alignment was touched up

Results:

Laser SN05  
Date June-26-2025
Laser Shutter Check Fail
Max OFS Offset 7.2V
95% OFS Offset 6.84V
Operating OFS Offset 3.42V
Laser Output Power 1.97W
Rejected Laser Power 3.3mW
AOM Input Power 1.92W
Max Diffracted Power 1.23W
Un-Diffracted Power 0.500W
AOM Diffraction Efficiency 64%
AOM Rejected Power 3.3mW
TxPD Power 1.4mW
OFSPD Power 1.73mW
Outer Beam Power 294mW
Inner Beam Power 292mW
Output Beam Power Ratio 0.9932
OFS Gain 7.50V
OFS Phase Margin 43.7
ALOG  
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francisco.llamas@LIGO.ORG - 16:58, Wednesday 02 July 2025 (85515)

After the maintenance I tweeked the AOM to increase the diffraction efficiency. The nominally, the diffraction should be above 70% efficiency, which translates to 1.34 W from the *Maestro*. My procedure went as follows:

  1. Set the OFS offset to the recorded max: 7.2 V on V2 of the HP power supply on the upper right (when looking from the front)
    • Once the offset is set, block the beam (be safe!)
  2. Placed the high-power head (HPH) before the AOM on the Tx module
    • Zero-ed the readout and then unblock the beam.
    • Readout: 1.92 W (consistent with maintenace done the day before).
  3. Placed HPH before the wedged beamsplitter
    • Readout: 1.24 W (consistent with maintenace done the day before).
  4. So far, everything is consistent with the maintenance. We can now adjust the AOM.
    • The AOM is placed on a New port stage, following the documentation for this component, the bottom screws will adjust the Y axis (height) and the top screws will adjust the X axis (angle of incidence).
  5. Adjusted Y1 and Y2 -- bottom left and bottom right screws, respectively. A counter-clockwise adjustment of each screw, to about one turn, increased the output to 1.28 W.
  6. Adjusted X1 and X2 -- top left and right screws -- to reach 1.30 W. Fine adjustments could not get a higher output.
  7. Returned offset to operating value of 3.42 V on power supply.

AOM alignment increased the efficiency to 67%, a gain of 3%.

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