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Section: H1
Task: PSL
The PSL PMC and RefCav have been slightly misaligned since the power outage, so today I took a bit of time to touch these up before the holiday break.
With the ISS off, I was able to only improve the PMC a bit, bringing PMC TRANS from 105.7W to 106.3W and PMC REFL from 25.5W to 25.2W. I then re-engaged the ISS and slightly adjusted the RefSignal to bring the diffracted power back to around 4%. Moving onto the RefCav, here I got somewhat better improvements, bringing the TPD signal up from 519mV to 530mV.
FAMIS 31117
Since I missed pulling these trends last week, I plotted a total of 17 days this time around. Overall, things look to be running smoothly. Robert was in the enclosure 6 days ago tracing cables, which shows clearly in the relevant trends. The PMC and RefCav have needed some alignment touchup since the power outage based on the beam images, so I'll do that either today or tomorrow before the holiday break.
Closes FAMIS27623, last checked in alog88538
Laser Status:
NPRO output power is 1.839W
AMP1 output power is 70.55W
AMP2 output power is 139.7W
NPRO watchdog is GREEN
AMP1 watchdog is GREEN
AMP2 watchdog is GREEN
PDWD watchdog is GREEN
PMC:
It has been locked 12 days, 15 hr 38 minutes
Reflected power = 25.34W
Transmitted power = 105.7W
PowerSum = 131.1W
FSS:
It has been locked for 3 days 16 hr and 18 min
TPD[V] = 0.5215V
ISS:
The diffracted power is around 4.1%
Last saturation event was 5 days 19 hours and 36 minutes ago
Possible Issues:
PMC reflected power is high
Betsy, Rahul
We found that SUS JM1 had a faulty quadrupus cable, which we replaced it today. Next, I took OLC for both JM1 and JM3 in HAM1 chamber. I applied the offsets, gains and then centered the BOSEMs - and they look good. Next, I will start checking the health of the electronics chain and the suspension itself (i.e. by taking the transfer function measurements).
The offsets and gain for JM1 is recorded in this screenshot - accepted in the SDF (safe).
The offsets and gain for JM3 is recorded in this screenshot - accepted in the SDF (safe).
Oli, Rahul
We started damping both the suspensions - found that the voltmons were not working (Dave found that their gains were set to zero).
With voltmons ON, both the suspensions were damping fine - no overflows on this 28bit DAC.
Adding pictures of JM1 and JM3 I took today.
Tagging EPO for JM photos
For the upcoming ISS array swap, we plan to bypass the IMC, which is known to be a pain, but we need a stable beam for the array alignment.
Once the corner volume is vent, we use the QPD on the old array and IMC-IM4_TRANS as the initial reference for bypassing the IMC. Once IMC is bypassed, we will center REFL WFS BEFORE removing the old array and record the RM1/RM2 PIT and YAW. This way, even if we somehow suspect e.g. the pointing of the beam going to the IM4 moved after removing the old array, we can still restore the pointing by looking at the REFL WFSs in addition to IM4.
We measured the beam positions on these QPDs today even though we'll repeat this later.
IFO configuration:
Arrow ("->") means before and after the REFL centering servo (DC1 and DC2) was turned ON:
| PSL-ISS_SECONDLOOP_QPD | IMC-IM4_TRANS | ASC-REFL_A_DC | ASC-REFL_B_DC | SUS-RM1-M1_DAMP INMON | SUS-RM1-M1_DAMP INMON | |
| PIT | -0.814 | 0.366 | -0.884 -> 0 | -0.995 -> 0 | 293 -> 168 | -363 -> 68 |
| YAW | 0.655 | -0.146 | 0.590 -> 0 | 0.220 -> 0 | -176 -> -214 | 277 -> -70 |
Septum cover is left OFF but the PSL light pipe was closed after this. REFL centering was turned off but I didn't bother to offload the ASC output to RM sliders.
REFL WFS nubmers as of now are not super meaningful as we'll still have to lock HAM2 down, which potentially change the relative alignment between HAM1 and HAM2. (But it's good that the beam is still hitting REFL WFSs after HAM1 was locked down even though Jim noted that the ISI position of HAM1 is not good. )
I'll open the light pipe tomorrow and quickly repeat the measurement after Jim locks down HAM2 HEPI.
Jim locked HAM2 HEPI today. I opened the PSL light pipe and locked IMC, and the beam was already reasonable on REFL WFSs without centering servo.
I'm convinced at this point that Jim does a good job that the angle change won't be large enough to lose the beam in HAM1 even after Jim locks down HAM2 in air. We will very likely find the beam on REFL WFSs after bypassing the IMC using ISS array QPD and IM4 trans.
As before, "->" means before and after the refl centering was turned ON.
| ASC-REFL_A_DC | ASC-REFL_B_DC | SUS-RM1_M1_DAMP INMON | SUS-RM2_M1_DAMP INMON | |
| PIT | 0 -> 0 | -0.39 -> 0 | 190 -> 174 | 108 -> 14 |
| YAW | 0 -> 0 | 0.07 -> 0 | -210 -> -214 | -69 -> -59 |
After this,
Betsy, Fil, Rahul
Today we kicked started the installation activities in HAM1 chamber for the Jitter Attenuation Cavity (JAC). Given below are the things we placed on the ISI table - they are all roughly positioned and dog clamped.
1. Tip Tilt JM1 - now connected to electronics chain, having some issues with the bosem adc counts etc, will continue looking into it.
2. Tip Tilt JM3 - now connected to the electronics chain, bosem centered, will proceed for health checks once the chassis and electronics chain looks okay.
3. The two periscopes for the JAC, Type 121 and 132 - assembly report posted by Jennie - 88574.
4. Some optics on Siskiyou mount were also added to the table.
I am attaching pictures which shows the above mentioned things added to the table - and for comparison a picture showing before any addition was (here) made.
Fil also performed group loop checks on JM1 and JM3 and did not find any issues with them.
EPO-Tagging for JAC installation
[Jason, Betsy, Masayuki]
Two arises are installed into HAM1 chamber. They will be used as the alignment reference for new PSL modematching lens installation.
Next step: move to the PSL and install the new mode-matching lens, likely tomorrow. This will break the IMC mode matching; IMC relocking will not be possible until the JAC installation is completed.
EPO-Tagging for HAM1 installation work
Closes FAMIS 27622, last checked in alog 88380
Laser Status:
NPRO output power is 1.86W
AMP1 output power is 70.35W
AMP2 output power is 139.5W
NPRO watchdog is GREEN
AMP1 watchdog is GREEN
AMP2 watchdog is GREEN
PDWD watchdog is GREEN
PMC:
It has been locked 6 days, 14 hr 45 minutes
Reflected power = 24.87W
Transmitted power = 105.8W
PowerSum = 130.7W
FSS:
It has been locked for 0 days 16 hr and 45 min
TPD[V] = 0.5086V
ISS:
The diffracted power is around 4.5%
Last saturation event was 0 days 18 hours and 22 minutes ago
Possible Issues:
PMC reflected power is high
[Joan-Rene Merou, Alicia Calafat, Sheila Dwyer, Anamaria Effler, Robert Schofield] This is a continuation of the work performed to mitigate the set of near-30 Hz and near-100 Hz combs as described is Detchar issue 340 and lho-mallorcan-fellowship/-/issues/3. As well as the work in alogs 88089, 87889 and 87414. In this search, we have been moving around two magnetometers provided to us by Robert. Given our previous analyses, we thought the possible source of the combs would be around either the electronics room or the LVEA close to input optics. We have moved around these two magnetometers to have a total of more than 70 positions. In each position, we left the magnetometers alone and still for at least 2 minutes, enough to produce ASDs using 60 seconds of data and recording the Z direction (parallel to the cylinder). For each one of the positions, we recorded the data shown in the following plotThat is, we compute the ASD using 60s FT and check the amplitude of the ASD at the frequency of the first harmonic of the largest of the near-30 Hz combs, the fundamental at 29.9695 Hz. Then, we compute the median of the +- 5 surrounding Hz and save the ASD value at 29.9695 Hz "peak amplitude" and the ratio of the peak against the median to have a sort of "SNR" or "Peak to Noise ratio". Note that we also check the permanent magnetometer channels. However, in order to compare them to the rest, we multiplied the ASD of the magnetometers that Robert gave us times a hundred so that all of them had units of Tesla. After saving the data for all the positions, we have produced the following two plots. The first one shows the peak to noise ratio of all positions we have checked around the LVEA and the electronics room:
Where the X and Y axis are simply the image pixels. The color scale indicates the peak to noise ratio of the magnetometer in each position. The background LVEA has been taken from LIGO-D1002704. Note that some points slightly overlap with other ones, this is because in some cases we have check different directions or positions in the same rack. It can be seen how from this SNR plot the source of the comb appears to be around the PSL/ISC Racks. Things become more clear if we also look at the peak amplitude (not ratio) as shown in the following figure:
Note that in this figure, the color scale is logarithmic. It can be seen how, looking at the peak amplitudes, there is one particular position in the H1-PSL-R2 rack whose amplitude is around 2 orders of magnitude larger than the other positions. Note that this position also had the largest peak to noise ratio. This position, that we have tagged as "Coil", is putting the magnetometer into a coil of white cables behind the H1-PSL-R2 rack, as shown in this image:
The reason that led us to put the magnetometer there is that we also found the peak amplitude to be around 1 order of magnitude larger than on any other magnetometer on top of one set of white cables that go from inside the room towards the rack and up towards we are not sure where:
This image shows the magnetometer on top of the cables on the ground behind the H1-PSL-R2 rack, the white ones on the top of the image appear to show the peak at its highest. It could be that the peak is louder in the coil because there being so many cables in a coil distribution will generate a stronger magnetic field. This is the actual status of the hunt. These white cables might indicate that the source of these combs is the different interlocking system in L1 and H1, which has a chassis in the H1-PSL-R2 rack. However, we still need to track down exactly these white cables and try turning things on and off based on what we find in order to see if the combs dissapear.
The white cables in question are mostly for the PSL enclosure environmental monitoring system, see D1201172 for a wiring diagram (page 1 is the LVEA, page 2 is the Diode Room). After talking with Alicia and Joan-Rene there are 11 total cables in question: 3 cables that route down from the roof of the PSL enclosure and 8 cables bundled together that route out of the northern-most wall penetration on the western side of the enclosure (these are the 8 pointed out in the last picture of the main alog). The 3 that route from the roof and 5 of those from the enclosure bundle are all routed to the PSL Environmental Sensor Concentrator chassis shown on page 1 of D1201172, which lives near the top of PSL-R2. This leaves 3 of the white cables that route out of the enclosure unaccounted for. I was able to trace one of them to a coiled up cable that sits beneath PSL-R2; this particular cable is not wired to anything and the end isn't even terminated, it's been cleanly cut and left exposed to air. I haven't had a chance to fully trace the other 2 unaccounted cables yet, so I'm not sure where they go. They do go up to the set of coiled cables that sits about half-way up the rack, in between PSL-R1 and PSL-R2 (shown in the next-to-last picture in the main alog), but their path from there hasn't been traced yet.
I've added a PSL tag to this alog, since evidence points to this involving the PSL.
[Joan-Rene, Alicia] We tried yesterday disconnecting the PSL Environmental Sensor Concentrator where some of the suspicious white cables were going, but no change was seen in the comb amplitude. Continuing our search with the magnetometer in the same rack, we found out that the comb is quite strong when the magnetometer is put besides the power supply that is close to the top of the rack:So it may be that these lines may be transmitted elsewhere through this power supply. We connected a voltage divider and connected it to the same channel we were using for the magnetometer (H1:PEM-CS_ADC_5_23_2K_OUT_DQ):
Out of this power supply, two dark green cables come out, the first one goes to the H1-PSL-R1 rack:
However, the comb did not appear as strong when we put the magnetometer besides the chassis where the cable leads. On the other hand, the comb does appear strong if we follow the other dark green cable, that goes to this object
Which Jason told us it may be related to the interlock system. Following the white cables that go from this object, it would appear that they go into the coil, where we saw that the comb was very strong. We think it would be interesting to see what here can be turned off and see if the comb does disappear.
FAMIS 31115
This week's check serves as a comparison on how things in the PSL came back after the long power outage last Thursday. Overall, things look good, with the exception that alignment is certainly needed into the PMC and RefCav (not surprising after the laser goes down), but we're waiting on full picomotor functionality to be restored before doing that. As is, alignment is fine enough for now.
One can see that after the system was recovered Thursday afternoon, for about a day, the environmental controls for the enclosure were in a weird state (see Jason's alog) which caused oscillations in amplifier pump diode currents and thus output power from AMP2. This has been fixed and behavior appears to be back to normal.
Additionally, the differential pressure sensor between the anteroom and laser room seems to have been fixed by the outage. Hooray.
Jenne sent me a Mattermost message this afternoon pointing out an odd "oscillation" in Amp2 output power, so I took a look. Sure enough, it was doing something weird. Ever since the power outage, on a roughly 2-hour period, the output power would drop slightly and come back up. I looked at items that directly impact the amplifier: Water/amp/pump diode temperatures, pump diode operating currents, and pump diode output. Everything looked good with the temperatures and operating currents, but the pump diode output for 3 of the 4 pump diodes (1, 2, and 4) showed the same periodic behavior as the amp output; every ~2 hours, the pump diode output would spike and come back down, causing the "oscillation" in Amp2 output power. See first attachment. But what was causing this behavior?
At first, I couldn't think of anything beyond, "Maybe the pump diodes are finally starting to fail..." Gerardo, who was nearby at the time, reminded me that during the last power outage the H2 enclosure had an odd sound coming from its environmental control system, and that it was not showing up on the control panel for the system; the control panel showed everything as OFF, but when Randy climbed on top of the enclosure he found one of the anteroom fans moving very slowly and haltingly, and making a noise as it did so. Turning the fans off at the control panel fixed the issue at the time. So, I took a look at the signal for the PEM microphone in the PSL enclosure, which Gerardo also reminded me of, and sure enough, the mic was picking up more noise than it was before the power outage (see 2nd attachment). Around the same time, from the front of the Control Room Sheila noted that Diag_Main was throwing an alarm about the PSL air conditioner being ON. It had been doing this throughout the day, but everytime I checked the AC temperature it was reading 70 °F, which was a little lower than normal but not as low as it reads when the AC is actually on (which is down around 67 °F or so). This time, however, when I checked the AC temperature it was reading 68 °F. Huh. So I pulled up a trend of the PSL enclosure temps and sure enough, every 2 hours it looks like the AC comes on, drops the temperature a little, then turns off, and this behavior lines up with the "oscillation" in Amp2 output (see 3rd attachment; not much data for the enclosure temps since those come in through Beckhoff, which was recovered earlier this afternoon, but enough).
I went out and turned every PSL environmental item (HEPA fans, ACs, and make-up air) ON then OFF again and placed the enclosure back in Science Mode (HEPA fans and AC off, make-up air at 20%). Won't know for sure if this cured the issue, as it's been happening on a 2-hour period, but looking at the PEM microphone in the enclosure shows promise. The PEM mic is not picking up the extra noise, it's back to where it was before the power outage (see final 2 attachments). Also encouraging, at the time of writing the AC temperatures are above the temperature where the ACs would kick on before I cycled the environmental controls. I'll continue to monitor this over the weekend.
Closes FAMIS#27621, last checked 88194
Everything looking okay except PMC REFL being high. It does look like it's been higher since they recovered the PSL after yesterday's power outage, but we are also still recovering and more will still need to be done for the PSL anyway, so maybe this is expected/will be adjusted anyway.
Laser Status:
NPRO output power is 1.83W
AMP1 output power is 70.67W
AMP2 output power is 139.9W
NPRO watchdog is GREEN
AMP1 watchdog is GREEN
AMP2 watchdog is GREEN
PDWD watchdog is GREEN
PMC:
It has been locked 0 days, 17 hr 9 minutes
Reflected power = 25.84W
Transmitted power = 105.6W
PowerSum = 131.5W
FSS:
It has been locked for 0 days 16 hr and 19 min
TPD[V] = 0.5027V
ISS:
The diffracted power is around 4.0%
Last saturation event was 0 days 0 hours and 0 minutes ago
Possible Issues:
PMC reflected power is high
R. Short, P. Thomas, J. Oberling
We have recovered the PSL after today's power outage. Some notes for the future:
I've attached a picture of the Settings table for PSL sensor calibration and operating hours for future reference. Again, our persistent operating hours (that track total uptime of PSL laser components; OPHRS A in the attached picture) will continue to be wrong as we cannot update this value. The current operating hours, which tracks operating hours of currently operating components (i.e. we've been running this specific NPRO for X hours; OPHRS in the attached picture) are correct.
We have the PMC and FSS RefCav locked, but have left the ISS OFF overnight while the PMC settles. The PMC requires a beam alignment tweak (normal after an extended time off, like a 90 minute power outage) but we don't yet have Beckhoff so we don't have access to our picomotor mounts. I'll tweak the beam alignment tomorrow once Beckhoff has been recovered.
FAMIS 27645
pH of PSL chiller water was measured to be between 10.0 and 10.5 according to the color of the test strip.
The RefCav reflected spot looked off this morning and the trends Ryan posted yesterday showed a large drop in RefCav TPD, so I tweaked the beam alignment into the RefCav from the Control Room; this was done with the ISS ON and the IMC unlocked. When I started the TPD was ~0.473 V, and when I finished the TPD is ~0.518 V. This isn't as high as we have been (~0.55 V), so this is an indication of another misalignment on the PSL table (most likely the double-pass AOM, which is our usual culprit for on-table alignment work). We're not too far down right now and we are not consistently observing, so we will continue to monitor as usual and will do an on-table alignment should the TPD continue to drop.
FAMIS 31114
RefCav transmission and ISS diffracted power have been dropping a bit while PMC reflected power has been increasing, but otherwise no major events over the past week while the IFO has mostly been down.
FAMIS 31113
Jason's FSS RefCav alignment tweak last week is clearly seen. Since then, the ISS diffracted power has dropped slightly and both PMC reflected and transmitted powers have risen sightly. No other major events of note this week.
Closes FAMIS#27540, last checked 88125
Everything is looking good.
Laser Status:
NPRO output power is 1.855W
AMP1 output power is 70.55W
AMP2 output power is 139.7W
NPRO watchdog is GREEN
AMP1 watchdog is GREEN
AMP2 watchdog is GREEN
PDWD watchdog is GREEN
PMC:
It has been locked 21 days, 18 hr 27 minutes
Reflected power = 24.49W
Transmitted power = 106.8W
PowerSum = 131.3W
FSS:
It has been locked for 0 days 0 hr and 40 min
TPD[V] = 0.5491V
ISS:
The diffracted power is around 3.9%
Last saturation event was 0 days 9 hours and 3 minutes ago
Possible Issues:
PMC reflected power is high
Related: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=87729
We disconnected everything from the ISS array installation spare unit S1202965 and stored it in the ISS array cabinet in the vac prep area next to the OSB optics lab. See the first 8 pictures.
The incomplete spare ISS array assy originally removed from LLO HAM2 (S1202966) was moved to a shelf under the work table right next to the clean loom in the optics lab (see the 9th picture). Note that one PD was pulled from that and was transplanted to our installation spare S1202965.
Metadata for both 2965 and 2966 were updated.
ISS second array parts inventory https://dcc.ligo.org/E2500191 is being updated.
Rahul and I cleared the optics table so Josh and Jeff can do their SPI work.
Optics mounts and things were put in the blue cabinet. Mirrors, PBS and lenses were put back into labeled containers and in the cabinet in front of the door to the change area.
Butterfly module laser, the LD driver and TEC controller were put back in the gray plastic bin. There was no space in the cabinets/shelves so it's put under the optics table closer to the flow bench area.
Single channel PZT drivers were put back in the cabinet on the northwest wall in the optics lab. Two channel PZT driver, oscilloscopes, a function generator and DC supplies went back to the EE shop.
OnTrack QPD preamp, its dedicated power transformer, LIGO's LCD interface for QPD and its power supply were put in a corner of one of the bottom shelf of the cabinet on the southwest wall.
Thorlabs M2 profiler and a special lens kit for that were given to Tony who stored them in the Pcal lab.
aLIGO PSL ISS PD array spare parts inventory E2500191 was updated.
I was baffled to find that I haven't made an alog about it, so here it is. These as well as other alogs written by Jennie, Rahul or myself in since May-ish 2025 will be added to https://dcc.ligo.org/LIGO-T2500077.
Multiple PDs were moved so that there's no huge outlier in the position of the PDs relative to the beam. When Mayank and Siva were here, we used to do this using an IR camera to see the beam spot position. However, since then we have found that the PD output itself to search for the edge of the active area is easier.
After the adjustments were made, the beam going into the ISS array was scanned vertically as well as horizontally while the PD outputs were recorded. See the first attachment. There are two noteworthy points.
1. PDs "look" much narrower in YAW than in PIT due to 45 degrees AOI only in YAW.
Relative alignment matters more for YAW because of this.
2. YAW scan shows the second peak for most of PDs but only in one direction.
This was observed in Mayank/Siva data too but it wasn't understood back then. This is the design feature. The PDs are behind an array plate like in the second attachment (the plate itself is https://dcc.ligo.org/D1300322). Red lines show the nominal beam lines and they're pretty close to one side of the conical bores on the plate. Pink and blue arrows represent the shifted beam in YAW.
If the beam is shifted too much "to the right" on the figure (i.e. pink), the beam is blocked by the plate, but if the shift is "to the left" (i.e. blue) the beam is not blocked. It turns out that it's possible that the beam grazes along the bore, and when that happens, a part of the broad specular reflection hits the diode.
See the third attachment, this was shot when PD1 (the rightmost in the picture) was showing the second peak while PD2 didn't.
(Note that the v2 plate which we use is an improvement over the v1 that actually blocked the beam when the beam is correctly aligned. However, there's no reason things are designed this way.)
We used a PZT-driven mirror to modulate the beam position, which was measured by the array QPD connected to ON-TRAK OT-301 preamp as explained in this document in T2500077 (though it is misidentified as OT-310).
See the fourth attachment where relatively good (small/acceptable) coupling was obtained. The numbers measured this time VS April 2025 (Mayank/Siva numbers) VS February 2016 (T1600063-V2) are listed below. All in all, horizontal coupling was better in April but vertical is better now. Both now and Apr/2025 are better than Feb/2016.
| PD number |
Horizontal [RIN/m] |
Vertical [RIN/m] |
||||
| Now |
Apr/2025 (phase NA) |
Feb/2016 (phase NA) |
Now |
Apr/2025 (phase NA) |
Feb/2016 (phase NA) |
|
|
1 |
6.9 | 0.8 | 20 | -0.77 | 34.1 | 11 |
| 2 | 7.1 | 2.7 | 83 | 5.1 | 2 | 25 |
| 3 | 8.2 | 5.5 | 59 | 2.2 | 4.4 | 80 |
| 4 | 8.8 | 2.3 | 33 | 0.30 | 1.1 | 21 |
| 5 | -19 | 5.1 | 22 | 11 | 12.3 | 56 |
| 6 | -14 | 12.9 | 67 | 16 | 30.4 | 44 |
| 7 | -18 | 10.2 | 27 | 2.9 | 42.7 | 51 |
| 8 | -19 | 5.3 | 11 | 12 | 52.1 | 54 |
Phase of the jitter coupling: You can mix and match to potentially lower jitter coupling further.
Only in "Now" column, the coupling is expressed as signed numbers as we measured the phase of the array PD output relative to the QPD output. Absolute phase is not that important but relative phase between the array PDs is important. The phase is not uniform across all diodes when the beam is well aligned. This means that you can potentially mix and match PDs to further minimize the jitter coupling.
Using the example of this particular measurement, if you choose PD1/2/3/4 as the in-loop PD, the jitter coupling of the combined signal is roughly mean(6.9,7.1,8.2,8.8)=7.8 RIN/m horizontally and mean(-0.77, 5.1, 2.2, 0.3) = 1.7.
However, if you choose PD1/3/4/7 (in analog land), the coupling is reduced to mean(6.9, 8.2, 8.8, -18)=1.5 horizontally and mean(-0.77, 2.2, 0.3, 2.9)=1.2.
You don't pre-determine the combination now, you should tune the alignment and measure the coupling in chamber to decide if you want a different combination than 1/2/3/4.
Note, when monotonically scanning the beam position in YAW (or PIT) edge to edge of PDs, some PDs showed more than one phase flips. When the beam is apparently clipped at the edge (thus the coupling is huge), all diodes show the same phase as expected. But that's not necessarily the case when the beam is well aligned as you saw above.The reason of the sign flips when the beam is far from the edge of the PD is unknown but there should be something like particulates on the PD surface.
The QPD was physically moved so the beam is very close to the center of the QPD. This can be used as a reference in chamber when aligning the beam to the ISS array.
After this, we manually scanned the beam horizontally and measured the QPD output. See the 5th attachment, vertical axis is directly comparable to the normalized PIT/YAW of the CDS QPD module, assuming that the beam size on the QPD in the lab is close enough to the real beam in chamber (which it should be).
EPO-tagging for ISS Array work
