IO work, 9 Nov

• beam is aligned to PR2
• REFL beam is aligned going into HAM1
• PRM sliders are at pitch = -150, yaw = 100, so close to the 0,0 alignment
• at the meeting I saw that the PSL temperature was high
• this is now being corrected
• not sure when the PSL temperature / PSL beam will stabilize
• IO work to continue after
• some mechanical relief of IM alignment drives will be needed
• aux. QPD signals still to align

- Cheryl, Jeff, Ed

BSC1, 2, 3 baffle and alignment work

Yesterday, we installed the ITMY elliptical baffle to see how it looked wrt the ITMY-SR3 IFO AUX simulation beam.  Unfortunately, after suspending it and tweaking the few top weights to try to center up the EQ stops as best as possible, the baffle target showed it was misaligned by 1cm from the beam.  Between this and the mystery miscentering on the BS elliptical baffle, we decided to move away from this arm of alignment work, and move on to see what other surprises turn up in the ITMX to PR3 simulated beam alignment path.  (Will consult with baffle docs and experts to review aligning the elliptical baffles if needed after we see corroborating stories between the AUX beam and the PSL beam heading our way soon.)  We:

- moved the AUX laser setup from the ITMY chamber to the ITMX chamber

- installed and carefully aligned the centering target on the ITMX

- removed the new baffle panel from the PR3 sus frame

- installed and carefully aligned the centering target on PR3

- installed the ITMX elliptical baffle

- removed the temp laser barrier between HAM3 and BSC2

Note, we did not suspend the ell baffle since we need to finish putting the balance weights on.

...to be continued.

Betsy, Travis, Jason, Jenne, TJ

OFI Optics Table

Table is ready to be removed from its cage, all earthquake stops were removed, earthquake stop plates, and suspension wires set aside.

Tomorrow the OFI table can be removed and moved to the optics lab for testing.

PSL Enclosure Make-up Air Found OFF

During today's 1pm PST meeting it was noticed that the PSL enclosure temperature had increased to over 80 °F, and had been increasing for ~18 hours.  After the meeting (~1:30pm PST) I went out and checked the status of the environmental controls and found the HEPA fans, AC, and make-up air all OFF.  The proper setting for science mode (which the PSL was supposed to be in for the ongoing IO alignments, see alog here) is HEPA fans and AC OFF, make-up air ON at 20% fan speed.  I restored the PSL environmental controls to the proper setting and the enclosure temperature should start slowly coming back down.  Something happened yesterday evening to turn off the make-up air entirely, at this point we are not sure what.

When I went into the enclosure on Tuesday, I also noticed that the "default" speed of the
ante-room and laser room HEPA fans was set at 20% (it should always be 100%).  I changed
it from 20% to 100%, waited a few seconds (~10), scrolled back through the menu to find
that the speed was set back to 20% again.  I had to repeat this two or three times to get
the default value to stick.

    I had left the make up air at 20%, the science mode speed.  By comparison with the
HEPA fan speed settings, the make up air setting seemed well behaved.  I left the air
conditioning off, without toggling the circuit breaker.

Running mechanical pumps near GV5 overnight

Ops Day Shift Summary

Move OneStopPCIe card on h1susey, glitch mitigation investigation

WP7213 Dave:

Gerrit discovered that the fast computer glitching is possibly related to the location of the OneStop card on the pci bus. All four of the LHO fast computers have the X9SRL motherboard from Supermicro. On this board, the first PCIe slot (slot 1) is connected to the PCH (Platform Controller Hub) while slots 2-7 are directly connected to the CPU. Several of the 2-7 slots share a bus, while slot 5 has its own bus.

I confirmed that the PCIe card layout on h1susey and h1susey were identical (slot order is as seen from the rear of the computer).

slot id	7	6	5	4	3	2	1
card	empty	empty	empty	VMIC-5565	Dolphin	OneStop	IRIG-B

In this layout, the OneStop card (slot 2) shares a bus with slot 3 (Dolphin) and slot 7 (empty).

To test if the ADC/TIM glitch rate could be reduced with a card reconfiguration, on h1susey I have moved the OneStop card from slot-2 to slot-5 so it has its own bus.

Before powering down h1susey Jeff started the SWWD bypass on h1iopseiey. Unfortunately, even though I completed the hardware change in the prescribed 20 minutes, the power cycle of h1susey caused a Dolphin glitch on power up, so this was for nought. All models on h1seiey and h1iscey were subsequently restarted.

H1 ISI HAM4 Locked

J. Kissel

Since Jim has cleared a cursory look at H1 HAM4 ISI transfer functions (LHO aLOG 39340), I've relocked the table in prep for up-coming full IFO alignment activities up-and-coming in the next week. #crossfingers #touchwood

In-situ isolation measurement of the OFI

[Gerardo, Koji, Betsy]

The in-situ measurements of the OFI optical isolation showed the numbers between 25.7 to 27dB. This is a factor of 2 to 2.7 too much from the requirement of 30dB. These are also too high compared to the expected value  from the measurement in the optics lab. We need to consider to pull the OFI table out and assess the optical performance in the opt lab again.

---

- The beam launcher was installed on HAM6 ISI. The table is fixed on the ISI table with two fork clamps.
- The alignment was surprisingly easy (by chance). Once the beam is adjusted to hit the output aperture of the OFI (i.e. the one close to HAM6), it also went through the input aperture (i.e. the one away from HAM6).

- We used 4 types of power meter heads for the islation measurement. 2 Ophir PD-type, 1 thorlabs thermal sensor (turned out not sufficiently stable for our purpose), and 1 Thorlabs' integrating sphere. The sensors were held by hand.

- The below shows the measurement results. Any measured isolation did not qualify the requirement of 30dB...

	Ophir PD #1	Ophir PD #1	Ophir PD #2	Thorlabs Integration Sphere
Beam launcher	NA	(56mW unstable)	47.7+/-0.1	40.4+/-0.1
OFI output [mW]	69.7+/-0.1	64.5+/-0.1	47.0+/-0.1	40.0+/-0.1
OFI input [mW]	0.18+/-0.01	0.13+/-0.01	0.12+/-0.01	0.107+/-0.001
Isolation [dB]	25.8+/-0.3	27.0+/-0.3	25.9+/-0.4	25.73+/-0.01

13:00 Vent Meeting Minutes

Fiber coupled beam launcher for the OFI in-situ isolation test

To make the post installation test for the optical isolation of the OFI, a fiber coupled beam launcher was constructed. It consists of two portable breadboards connected with a PM-SM fiber.

The first attachment (input_table.jpg) shows the source part. This table is placed at a chamber side. An NPRO is mounted on the table and mode matched to a fiber coupler via a f=50mm lens. The max incident power to the fiber is about 100mW and the coupling efficiency was measured to be 81% max.

The second attachment (launcher.jpg) shows the beam launching part. This table is placed on the HAM6 ISI table. As the OFI is placed at the edge of the HAM5 table, we need to shoot the beam from HAM6 at the optical height of 4". The components on this table have been cleaned to be (at least) CLASS B. The output beam is converted to a thick beam with a f=100mm lens. The output mode is measured with Mode Master (the third attachment). It shows the Rayleigh range of ~3m. i.e. The beam radius is ~1mm and is intentionally smaller  (about a half) than the PSL beam size there to make the in-situ measurement easier.

They are transported to the HAM6 side this morning. The laser power supply is connected to an interlock-enabled power extension laid out from SQZ Bay. We also have the local kill switch.

WHAM5 ISI Optical Table Level check--Very Level

Gerardo stated that the Optical Table was not very level using a small T-Level and that the OFI needed adjustment to hang properly after doing all the adjustments on an optical table bench.

So I used the Optical Auto Level to look at the table.  With seven shots, above the walls at every corner and in the center of the table, the range of level was +-0.1mm--very level in our books.  I did manage to tie it into our LVEA monuments to put an actual elevation on the table: -325.8mm Lz.  Adding the -0.3mm conversion from local the global gives -325.8mm Gz (See T1100187.)  Looking at D0901129, it shows the Optical table to be 325mm below the BEAM TUBE CL.  I can't tell or remember if this is below the HAM5 BT CL or below the BSC2 BT CL where global 0 0 0 is positioned.  Either way, we are within 0.5 to 0.8mm of ideal elevation for this Optical Table and again very level.  Frankly, I'm relieved!  Attached are my field notes.

IM alignment slider calibration, details to remember

The alignment slider gains are set to 0.05urad/slider count, see alog 30106.

• for the ideal case where the there is no saturation on the coils
• a 5000 count change on the alignment slider is 250urads of change in the optic angle
• at 1m from the optic, the beam position change is 0.25mm
• the full range of the alignment slider is 120000 (+/-60000)
• the beam position change at 1m for 120000 slider counts is 6mm (+/-3mm from the zero alignment slider position)

fast shutter triggering

I started to look at times when the fast shutter fired to check if there are times when more energy passed the shutter than desired (in part because of the broken beam dump in HAM6).  I wrote a script that looked at about 40 days of minute trend of the AS WFS (which are behind the shutter) and picked out times when they were high.  Attached are plots of the three events where the most energy seems to be getting past the shutter in those 40 days.  In all of these three cases, the power on the AS_C PD doesn't seem to have exceeded the threshold for the shutter to fire until there had already been several seconds of large power fluctuations at the AS port.  The shutter triggers as expected when the power goes over the threshold.

• Beckhoff channels are reporting events happening about 0.1 seconds before the front end (39329) For this reason I've shifted the time of all the channels labeled beckhoff in the attached plots by +0.125 seconds.
• I do not understand the behavior of the channel labeled Shutter G Trigger.  The best explanation I can think of for what I see is that this is somehow the shutter is triggered on AS WFS DC.  The channel labeled SHUTTER G Trigger Volts is the beckhoff channel which Koji and I believe should be a readback of the outputs labeled PD+ and PD- on sheet 2 of D1102312.  (For reference, see the diagram of the fast shutter wiring in E1300819 QPD amp is D1001974 shutter controller is D1102312 and shutter driver is D1400078)
  • The voltage read back by the Trigger Volts channel spikes and goes to zero after the trigger fires, similar to the AS WFS channels which are behind the shutter.  AS_C should not be blocked by the shutter firing, and goes to zero more slowly after the lockloss transient has passed.  I went to the floor and sent a DC voltage into the shutter controller, as you would expect the readback of the trigger volts channel is not impacted by the shutter triggering.
  • DC power:
    • This trigger comes from the sum on D1001974  I believe this should have a gain of 0.2485V/mA on the QPD (a factor of 10 smaller than what is on the schematic), because there is the transimpendance of 1kOhm, then a gain of 0.2485 before the summation.  The normal photocurrent from the diode then is about 1mA.  (I checked with a calibrator that putting 1 V into the shutter driver input results in 1V read back in beckhoff)
    • The calibration of the AS_C channel into mA is 1V/mA (TI gain)*2 (differential driver in TI amp chassis)*10^(36/20)whitening gain*1638.4 cnts/V = 2/07e5 cnts/mA.  By undoing the front end calibration into Watts into HAM6 (29078) we can estimate that AS_C has about 0.125 mA photo current. 
    • We expect about 10 times more power on the AS WFS than AS_C, since we have 800 ppm for OM1 (plus 50% splitter) and 1% transmission for OM3 (split between 2 WFS).
  • Two caveats:
    • There is a jumper in the transimpedance chassis which can be used to turn on the 0.4z40p whitening stage, (this is after the trigger spigot) we are currently compensating this in the front end but if it is not on that could explain why AS_C sometimes overshoots and goes to zero.
    • I checked the cables, and everything seems to be as it should be.

IO Work Day Summary Nov 8th 2017

J. Kissel, E. Merilh, C. Vorvick

Below is a summary of what Cheryl led us through today:

 - PRM and PR2 Irises placed in-vacuum
 - Performed daily alignment of IMC by adjusting PSL PZT, and IMC Mirrors
 - IMC flashing speed reduced by turning down HAM2/HAM3 purge air
 - IMC alignment fine-tuned by driving MC2 broadband in L from 0.2 to 0.25 Hz (to have RMS velocity dominated by a slower pulse than the 12 Hz HEPI pier resonance noise)
 - IM1&2 alignment finalized (via sliders / actuators) using IR card views of flashing beam at Faraday Isolator input and output apertures 
 - Flashing beam routed through to PR2, but found that IM3 needs entire DAC range in Yaw (consistent with what was seen during first observing runs)
 - IM3 alignment mechanically offloaded in Yaw using OSEM sensors
 - Re-tightened all IM3 cage / structure bolts

A video of the flashing can be seen here: https://youtu.be/8DJnQ45cmK0. The speed at which the IMC is flashing through alignment fringes is reflective of the 12 Hz pier resonances transmitted through the locked HEPI and ISIs in HAM2 / HAM3 (see LHO aLOG 39328).

Attached are screenshots of:

 - The evolution of alignment sliders during the daily re-alignment of the IMC in Pitch and Yaw
 - Screenshots of OSEM positions and alignment sliders after we finalized the IMC alignment 
 - Screenshots of OSEM positions and alignment sliders after we finished alignment of IM1 and IM2, and after mechanically offloading IM3

We ran out of time today given the extra work with IM3, but we will resume tomorrow morning around ~10a, with the end-goal to install the IMC bypass and hand off to further down-stream alignment of the IFO.

Any work that needs laser safe will be free to work laser glasses free for a few hours in the early morning.

BS HR Elliotical Baffle Alignment

Since Monday, Jason, Travis and I have been working on (amongst other things) the BS elliptical baffle rebuild and realignment.  Once all parts were in hand, the rebuild was straight forward.  Travis used the removed HR and AR baffle assemblies to line up and preassemble the mounting brackets so that the new baffles went in roughly where the old ones used to be positioned on the BS suspension structure.  However when we put the target on the HR panel, we discovered one of GariLynn's earlier worries - the baffle was off center by many millimeters.  Looking at the baffle relative to the structure seemed to indicate the same thing - the beam was left and down when looking at the HR surface target (meaning, the baffle was potentially too far up and right relative to the simulated IFO beam).

Unfortunately, this target-mounted-to-the-elliptical-baffle is what was used to align the entire BS SUS/ISI cartridge in the chamber install in ~2013, as per IAS procedure E1200795.  This fact lead us to spend a day or 2 sorting out how to tell if the BS optic is misaligned in the chamber (without any IAS measurement ability), and how we possibly could have installed the elliptical baffle out on the cartridge in the first place many years ago.  During this we went back in-chamber to make "precise" measurements.  We used Class B rulers to measure where the IFO simulation beam was hitting the BS, how well the BS is centered in the structure, and exactly where the beam was hitting the target.  Attached are actual sketches and pictures with detailed numbers.

Here's what we were able to measure to within ~1mm error since it's by-eye and other knowns:

1) The beam is hitting the center of the BS optic 2mm to the left of the optic centerline.

2) The optic is suspended in the structure to within 1mm or less of error.

3) The beam is hitting the HR target baffle 5.5 mm left of the target center.

4) Our Y-arm IFO simulator beam which runs between the ITMy center and the SR3 center ran dead center on the ITMY elliptical baffle (prior to it's removal) and the HWSY path a few weeks ago when HAM4 work was checked.

5) Per IAS procedure E1200795, the BS suspension to ISI locations were performed via more direct methods which did not involve the Baffle target, so we believe the BS to ISI mounting is correct.

Point 1) and 2) give us some confidence that the error of the BS optic placement is not as bad as how the baffle target indicates.

Some consult with GariLynn and Jenne, to understand what centering is most important from various aspects (including looking at some modeling done by Hiro in T1400055) and we have come to the conclusion that we will carry on as planned.  Namely, to first order it is best to have the baffle aligned very well to the beam.  Our next steps will be to recheck the IFO simulation beam pointing again, align the HR baffle to it, and take a series of pictures to ensure that the edges of the baffle are lined up correctly with the edges of the BS optic from the beam POVs.

Also during our walkabout over the last 2 days, we re-interpreted Keita's BS centering/beam clipping alog 28196, pointed out by Sheila.  Because it is difficult to see the edges of the BS optic when the baffle is installed, it seems Keita made some geometrical analysis of the HR and AR baffle positions to determine the position of the BS center.  However, since we believe the baffle was mounted in the wrong position by a few mm, his centering numbers likely are not correct.  Still, his numbers indicate the same directions of error as we see - the beam is hitting left and low of the baffle/optic.  I think we can repeat this measurement in the future by scaling the known diameters of the baffle holes and BS optic size on the camera view pictures.  Will think on this more.

 

H1 SUS PRM & PR3 B&K Hammer Results: Venetian Baffles Have Resonances b/w 30-100 Hz

J. Kissel

I've taken new, more comprehensive B&K hammer response measurements of the H1SUSPRM and H1SUSPR3 cages, now that they have newly installed (what I'm calling) Venetian Baffles (see attached HAM2_NewBaffling_WithLabels.pdf for names of baffles) whose installation was finished last week LHO aLOG 39170.

These baffles have pretty high-Q, low-frequency drum-head / longitudinal resonances (roughly aligned with ISI / IFO Y axis).
  
    PRM Upper: 42.38 & 46.75, 91.00
    PRM Lower: 42.38 & 46.75, 75.62 

    PR3 Upper: 36.75, 75.6
    PR3 Lower: 36.75, 83.12 

My guess is that the lower frequency of the modes are the baffles bending in longitudinal in concert on the Venetian bracket, and the upper frequencies are their individual longitudinal modes. This mode-shape guess is based only on intuition, and that the lower frequency modes are seen in both upper and lower excitations.

The cage's transverse modes appear to be relatively unaffected by the new baffles. I'm little surprised it hasn't stiffened up any of the transverse modes; oh well.

These resonances have been identified by comparing against the history or cage resonance measurements for each of the SUS -- see the three pdfs: 
    2017-10-30_H1SUSPR3_CageResponse.pdf
    2017-10-30_H1SUSPRM_CageResponse.pdf
    2017-10-30_H1SUSPRMvsPR3_CageResonance_Comparison.pdf

Note, also new with these measurements -- data out to 1.1 kHz. The former data is from 
LHO aLOG 6014 -- VA ON vs OFF data for H1SUSPRM and H1SUSPR3
LHO aLOG 8654 -- Former Cage Baffles on H1SUSPR3

Photos attached (and remaining HitLocations.pdf) are for historical reference for future repetition.