TITLE: 08/12 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: CALM
    Wind: 2mph Gusts, 0mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.06 μm/s 
QUICK SUMMARY:

Went to EQ Mode twice overnight.  On the docket for today:  HAM7 close-out begins, Input Alignment work will continue, CDS w/ DAQ restarts in afternoon, HAM8 Annulus Ion Pump activity, & DOE tour in the afternoon.

Summary

We have calibrated the two JAC steering actuators the PZT (IO_MB_M4) and the JM1, in μrad per drive count at DC. The scale comes from the second harmonic of the cavity transmission under a dithered drive, which is insensitive to DC misalignment and so needs no external angle reference. 

Method

By expanding the injected field in the cavity's own eigenmode basis, we can describe the misaligned as,

Ein(t) = E0 + δ(t) E1

with E0 the cavity's TEM00 mode and E1 the TEM10 (pitch) or TEM01 (yaw) mode, orthonormal. As long as the misalignment is small enough comparing to the beam size, the single complex coefficient δ carries the whole misalignment on that axis: its real part is a transverse displacement in units of the waist size, its imaginary part an angle in units of the divergence angle. Only the TEM00 is resonant, so the transmitted power follows the fraction of the input that sits in E0, i.e. 1 − |δ|2 for |δ|2 « 1.

Dithering a steering actuator makes δ oscillate about whatever value it already had:

δ(t) = δofs + δa cos(2πft)

where δofs is the static misalignment already present, and δa is the dither we deliberately applied, which is exactly the quantity we want in order to calibrate the actuator. TRANS signal (1 − |δ|2) can devided into three components with its frequecies:

The static offset drops out of the second harmonic algebraically. 2f therefore delivers |δa| with no reference to the alignment state we happened to be sitting at, and with no external angle standard. The DC and f terms, the two one would reach for first, are both contaminated by it.

This is the whole point of the method, and it is directly visible in the plot. adding a static offset grows the 1f line by +528 % while the 2f line moves by +8 %, its own measurement noise.

Measurement

I proceeded 4+1 measurement in total with the JAC locked. For each measurement, one actuator axis was dithered at 11 Hz, with the excitation injected on the channels below and the drive read back on the corresponding _OUT. I excited JM1/PZT PIT/YAW per one measurement, and the other one is the PZT_PIT excitation with static offset (30 cnts) to demonstrate that the 2f peak is not affected by the offset. Transmission was read on H1:JAC-TRANS_A_LF_OUT.

|δa| is calculated from peak heights of the transmission at 22 Hz, converted to a mirror tilt using the local beam radius at each actuator from the current JAC reflected-path layout model (alog91472 comment), and calibrated into DC responce using each actuator's frequency response as measured (described below).

Results

The 11 Hz column is what the dither actually produced; the DC column is that value divided by the actuator's own response at 11 Hz, and is the number to use for a DC gain. 

Appendix

Actuator frequency response

The frequency response itself comes from a separate set of four broadband actuator-to-wavefront-sensor records (300 s each, one actuator per record, see atatched plots), from which the JM1 suspension resonance and the PZT drive pole are fitted. Only the shape of those transfer functions is used; their absolute scale plays no role in the calibration.

The fitted frequency responses are:

• JM1 — complex pole pair, f0 = 2.00 Hz, Q = 7.7 (PIT) and 1.80 Hz, Q = 5.4 (YAW)
• PZT — single real pole at fp = 1.24 Hz (PIT) and 1.30 Hz (YAW)

AOI compensation

Both actuators sit at a design AOI of 45°, and the rows above include the geometric correction that follows. A tilt whose rotation axis lies in the mirror surface and in the plane of incidence steers the beam by only 2θ cos(AOI), against the full 2θ for the axis perpendicular to that plane. At the PZT the suppressed axis is YAW in the cavity-referred channel naming (the HAM1 periscope exchanges the transverse planes downstream of it); JM1 sits after that periscope, so for it the suppressed axis is PIT. The assignments follow from each mirror's orientation, and the correction uses the design 45° rather than a value fitted to the measured ratio.

Cross-checks

• JM1 against its own OSEM signal. I compared the numbers above with the OSEM output with a rough single DC-step reading. The difference between the calibration factor are: 1.17× (PIT), 1.02× (YAW). 
• PZT against its design value. The design chain is APZT = 500 μrad/V (T1500342) driven through an 18-bit DAC (±10 V differential, i.e. 20 V over 2¹⁷ counts) and a differential-to-single-ended board (D1100457 v2, unity gain, read off its schematic), giving 0.076 μrad/cnt. No further driver gain applies on top, since the T1500342 figure is referenced at the controller's control input. Our result sits at 1.09× (PIT) and 1.04× (YAW) of this designed value.

FAMIS 63911

PMC REFL has been rising very slightly, but otherwise, no major events of note.

(Travis S., Gerardo M.)
Around 11:00 am today we opened GV8 from soft close to allow for commissioners to peek down x-arm.  The gate annulus for GV8 was burped into the annulus ion pump, almost no response.  The 4 turbo pumps were isolated from the main vacuum envelope, the 4 large ion pumps are valved in, along with HAM6 ion pump (500 l/s), and we still have a filter cavity section valved into the main corner volume, the section from FCV-3 to FCV-4, and includes ion pump B-1 (150 l/s).
GV8 remained open for about 5 1/2 hours.
We closed GV8 around 16:30 local time.
Attached is a pressure response from gauges along the X-arm at the corner station.

TITLE: 08/11 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: GV8 was opened and closed today for Xarm alignment commissioning, ZM4 PSAMs adjustment was finished up. We had a small power glitch in the afternoon that tripped off the end station HEPIs.
LOG:                            

The gate phone microphone doesn't seem to be working well, one instance I heard nothing after answering, the next was garbled and full of static.

• 16:45 UTC transition to Laser Safe bifurcated
• 18:00 UTC transition to Laser Hazard
• 18:06 UTC GV8 is open
• 18:15 UTC started with the baffleAlign scripts
• 19:48 UTC a  power glitch flickered the lights in CR and tripped the End station HEPIs then ISIs
  • Fil&Jackie to EndY, Jim to EndX, to reset VFD plus other work for Fil
• 20:57 UTC BS ST2 ISI tripped
• 21:12 UTC Xarm locked in green with ir flashing
• 22:00 UTC I ran a health check TF on ZM4 after Rahul and RyanS were finished at HAM7
• 23:00 UTC Masayuki requested Aquire_PRMI in ISC_DRMI and there were flashes ~100
• 23:22 UTC GV8 soft closed

Camilla, Oli, Caroline, Masayuki, Sheila

• Before starting the arm peak Masayuki and I aligned PRX and MICH based on the alignment that Louis aloged in 91463  We are seeing flashes of up to 150 coutns on LSC POP A, 130 counts on the ASC POP QPDs, and nothing in POPAIR.  (1st screenshot)
• Once the gate was opened we ran the TMS to ITM baffle PD script without issue.  Caroline and Oli searched for the ETM baffle PD using an awg, and found it, then were able to run the baffle PD script for ITMX.  (2nd screenshot)  This ITMX pitch is different by 50urad.  
• We moved PR3 back to it's O4c alignment, Masayuki and Sheila went to ISCT1 to look for single pass green beam.  We saw it but very low in pitch, adjusted PR3 alignment to put it on the ALS X camera and trans PD.
• Camilla, Oli and Caroline tried to align ETMX using the baffle PD script, but this didn't work well. Once the table was aligned the switched to rastering the ETM and watching for flashes in the camera and trans diode.  
• Just as they were starting to see the flashes, the site power glitched and the HEPI pump controllers went down.  Jim went to EX to bring it back.
• Meanwhile, 10W single bounce off ITMX Masayuki moved IM4 to center the beam on POP X, and PR2 to bring the ITMX reflection onto the REFL PDs and refl camera.  After that worked he aligned PRM to get PRX flashes, then aligned BS for mich fgringes. 
• The single bounce beam looked clipped when SR2 was adjusted to center on the AS camera and AS_C, although the power on AS_C seems correct (0.02W into HAM6 with 9W on IM4).  When we moved SR2 to being the beam high on the camera and QPDs it looked like a normal shape.  Masayuki walked BS and SR2 to try to correct this.  
• Once HEPI was recovered we found the arm flashes in green and locked.  We could not engage slow feedback to the ETM but requested LOCKING from the guardian.  
• Camilla and Sheila aligned the COMM beatnote on ISCT1, and slightly adjusted PR3 pointing to avoid clipping on the path to the beatnote BS.  We got a beatnote of 0dBm, but we can see that the beam is slightly clipped on the prism.  
• Masayuki aligned IM4 and PR2 to get IR aliged to the X arm.  He was able to lock it with a normalized power of 0.95 (close to the nomial 1).
• Masayuki aligned PRM using PRX, and BS using MICH. 
• Sheila and Masayuki went to ISCT1, moved the POP top periscope mirror closer to REFL and down.  We should move the whole periscope over towards refl soon, to center on the pop top periscope mirror.  Then we aligned the rest of the path through to the POPAIR B diode, we see 120 counts on RF18.  
• Masayuki double checked the beatnote, it is -1dBm.  (final screenshot)

R. Kumar, S. Dwyer, C. Compton, R. Short

Following the work done yesterday adjusting the preload on the ZM4 PSAMs (alog91471), Rahul and I set about adjusting it further today to get our calculated projected beam size on SRM close to where we want it. Using the same procedure as yesterday, I turned off the ZM4/5 PSAM drive chassis, Rahul went into HAM7, locked down ZM4, torqued the preload about 1/8" of a turn (it's hard to quantify a torque spec in this manner), then finally unlocked the suspension. I moved the ZM4 pitch alignment slider about -1400 counts to realign the beam on SQZT7 to our alignment irises as a result of this torque adjustment. I then proceeded to take a couple of beam profiles on the table with the M^2 device to see where we landed. This plot [initial] shows the difference between before and after this adjustment in terms of the projected beam at SRM with a few different PSAM settings on ZM4 and ZM5. The four points I took here informed us that we could stand to torque ZM4 a bit further to hopefully line up with the center of the plot.

Rahul went back into HAM7 and torqued another 1/8" and I took another couple of profiles after (I did not need to move ZM4's alignment sliders after this adjustment). I took a total of nine profile points here, all of which can be seen compared to other measurements today on this plot [full]. Since there are points in the bullseye, we decided to stop here and that this is where the ZM4 preloading will stay. This plot [final] shows just the beam profiles taken at our final preloading position.

Tomorrow we will move on to final closeout checks in HAM7.

Jennie W, Sina K, Jim W,

Summary: Yesterday we had a check through the SPI model just to make sure we have turned on everything and that all is working well, we got as far as ascertaining that no light was making it to the PDs on the ISIJ and K benches and also did some other checks on the LO aand longitudinal IFO paths.

Couple of things we discovered/checked:

• Checked LO using dtt (the 4kHz signal is too fast to show up on ndscope as a sine wave and looks sawtooth) and it looks good. Attached are the various channel we checked starting with the common analogue sin and cosine shown with the first two arrows on the left in the LO screen. The phase of the common path phase rotator should be set to 0 so the signal should be unchanged at the next set of arrows in this picture. We checked those in dtt also here and they lie under the first two traces.
• The phase rotators in the sine and cosine paths should also be set to 0 and leave the next two arrowed channels unchanged, which they do except from the amplitude which is intentionally different (see next point).
• We decided to set the oscillator input gain to 1 in the digital oscillator (this was previously 1000) and put this gain in the output conditioning blocks (by switching off mV2V filter) which get sent as analogue signals to the double mixer. This large number is chosen specifically as the amplitude of signal neede to drive the double mixer so we feel it makes more sense to put it here.
• Some of the display channels in the medm LO screen are too low sampling frequency to display the 4kHz signal. We changed the displayed output channels H1:SPI-H23_LO_ANA_SIN_OUTMON, H1:SPI-H23_LO_ANA_CLK_OUTMON and H1:SPI-H23_LO_ANA_COS_OUTMON from the SIN and COS blocks to read the _OUTPUT channel instead.
• We will also add in some cdsfilt modules at the output of the digital oscillator module H1:SPI-H23_LO_SRC in order to get fast output channels on the medm. This requires model changes so we will implement when a DAQ restart does not interfere with cornber commissioning efforts.
• We corrected the screen SPI_CUST_IFO_DEMOD as it was displaying the phase channel for the wrong cdsPhase part (H1:SPI-H23_LO_ANA_COMROT) instead of (H1:SPI-H23_IFO_{MEAS,REF}_{A,B}_DEMOD_PHASE).

NB: We found out today that the shutter controller for our laser pick-off was not connected - Jim and Fil have now solved this (alog #91467).

TITLE: 08/11 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: CALM
    Wind: 9mph Gusts, 4mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.06 μm/s 
QUICK SUMMARY:

• A few CDS tasks on the docket for today
• CRS work as well
• Optics lab and EX dust alarms
• The AQI is decent this morning at good/28, but it's predicted to worsen to moderate

Workstations were updated and rebooted. This was an OS packages update.  Conda packages were not updated.

Rahul, Ryan, Sheila

Today we think that we found a rapid way to iterate the psams preloading, and we made a couple of changes for ZM4.  

Frst Ryan and I measured the beam profile with ZM5 psams servo set to -8V, and ZM4 psams PZT votlage at 0V,  

Rahul can add the details of how he did this, but he added about 1/8 turn of torque to the ZM4 psams.  We then turned the laser back on, and took a beam profile measurement.  Unfortunately the profiler software got into a strange state where the beam waist seemed to be at a very different position and it would not calculate the original beam parameters.  We thought this was because the beam profile had changed dramatically, and Rahul backed off the preload by 1/8 of a turn.  As we were remeasuring the profile Ryan S noticed that the range of the translation stage displayed on the screen went only from 0-100mm, while it normally goes from 0-200mm.  The software would not allow Ryan to reset the measurement range parameter, until we powered the profiler off, exited the software, and started both up again.  

After this, we saw that indeed we had a reasonable q measurement, although not really an improved mode matching. It does seem promising to adjust ZM4 this way, as each iteration took about 30 minutes including our confusion about the beam profiler.  

S. Dwyer, J. Oberling, L. Dartez

This afternoon we went to ISCT1 to align the green beam from the PSL Green PD, and ALS COMM PD. This is pre-peek prep so that by the time the peek takes place we don't need to worry about the beam alignment from the PSL.

We struggled a little bit to find an alignment that agreed with the crystal and the downstream PDs. We were able to get a beam onto the COMM PD. Sheila thinks that what we set up so far is more than enough to get a beatnote during the arm peek. We aligned the green beam onto the green PD but for some reason couldn't get see a readout signal that corroborated that the beam had made it onto the diode. We tried doing some troubleshooting, which included a local cable swap and adjusting the PD placement on the table. Neither were successful and, given the time of day, we opted to revisit at a later time. The important part thing is that the COMM PD _was_ seeing the beam. 

Jennie and I were looking at the SPI with Sina during a call today and Sina pointed out there was no power on the first PDs on the SPI breadboard. She said there was a witness pd in there SPI laser chassis that could be checked with a multimeter next to the chamber, so I went and checked that this afternoon. I'm not totally sure what all of the labels meant, but I think there is no laser light on the pd in the interface chassis. The SPI_LP_M1_PD was at 0v, the other two, SPI_LPMON_M2_RFMEAS and SPI_LPMON_M3_RFREF were at ~.8v regardless of the state of the CDS control of the SPI pick off shutter, which I had Ryan toggling remotely. We've talked to Ryan and Jason about going into the PSL tomorrow to check the function of the SPI pick off shutter, I think we will also try to check the output of the fiber at the chassis with a laser card at least. Not sure how hard it would be to look with a power meter.

Jennie Wright, Masayuki Nakano, Khanh Vu

This morning we worked on several tasks on the IOT1 table, including installing the camera and shutter, profiling the beam, and calibrating the DC power.

We identified a new location for the camera using the beam transmitted through JACR_M5. During this process, Masayuki noticed that the beam was being clipped by the shutter. We suspect that the beam may have been clipped for some time. We then installed the camera in its new location, and Masayuki aligned the shutter on the table.

Next, we profiled the beam for the wavefront sensors. We found that the Gouy phase separation between the two WFSs is approximately 70 degrees. We decided to leave the current configuration as it is since the separation is good enough. Masayuki will make a plot and perform a more detailed calculation later.

We also maximized the laser power in the REFL path by optimizing the waveplate angle. When JAC is unlocked, the measured power on the RFPD is 5.1 mW, and the trigger PD voltage is 0.28 V. When JAC is locked, the measured power decreases to 0.4 mW, and the trigger PD voltage is 0.02 V. Since the beam is split evenly, each WFS receives approximately 2.55 mW of optical power.

Finally, we calibrated the DC readout of RFPD by converting counts to mW. Before performing the calibration, Masayuki checked the alignment and recentered the RFPD. He then recorded two sets of measurements, each averaged over 10 seconds:

Measurement #1

* JAC_REFL_A_LF_INMON: 1072.3966186523437 counts
* DC power: 4.4 mW

Measurement #2

* JAC_REFL_A_LF_INMON: 1073.5228637 counts
* DC power: 4.5 mW

After the calibration, we updated filter number 10 with the new coefficients.

Keita, Sheila, Tony,  Jennie W

Before the JAC PZT problem, I did get an hour or so of alignment time in.  Summary: we now have light on LSC POP and POP X for the same PM1 alignment, and ITMX is back to the alignment that should point down the arm.  We have the expected power in LSC POP path, but a factor of 20 too small in both DC and RF signals in the popair path. 

These screenshots show MICH fringes with 10W input power, where I started and where I ended.  The idea was to move to the ITMX alignment that Jenne Driggers found using the arm beam here: 89738.  I watched the mich fringes and AS camera while moving the ITM, moved the beam splitter to keep the michelson fringes, and as Keita suggested moved PR3 to keep the beams on the ISCT1 refl camera.  This did cause the michelson fringes on the LSC pop diode to get smaller, when that happened I paused, went to the PR2 spot move guardian state, and adjusted PR3 to bring the fringes back on LSC POP.  After bringing the ITMX yaw alignment back I could see that there is now light on POPX and LSC POP A for the same PM1 alignment.  

When I walked ITMX pitch, I had to also adjust yaw several times as I went along to keep the mich fringes.  I also adjusted PRM to keep PRX alignment good as I moved along. Looking at this screenshot of the brief time when PRMI was flashing, the POP A LF flash was about the O4 power level (91211), as was reflair A, but popair has too little power.   The result of this was that PR3 started the day 56urad away from the O4 slider, but is not -15urad.  PR3 yaw started the day close to the O4 slider but is now -47urad.

I also adjusted the POP X dark offsets so that this QPD will be less confusing to read, SDF screenshot attached.

We tried walking PR3 in PR2 spot move to allow us to centering POP X without saturating PM1, this alignment is shown in this screenshot, but when we then aligned PM1 to put the beam on LSC POP, we were missing power there.