S. Muusse, T. Roocke

All chassis were put on the rack for the Y table and cables attached. All electronics were tested and working however, we have realised additional power supplies are required and some additional cables are required.

Power supply/ cables still required:

• 15V for flipper
• 12V for fan 
• 5V for visible
• Make cables for fans
• Make cables for flipper

A potential solution is to use pre designed 15V, 12V, 5V, regulator boards in another chassis which can be input to the table through the blank and power feedthroughs.  Alternatively there are some preexisting supply boxes for 12 and 15 V

TITLE: 03/07 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: We ran into issues trying to lock the IMC after locking JAC and GREEN_ARMs, it seems to be from MC1 (T2 and T3 mostly). 
LOG:                                                                                                                                                                                                                                                                                                                                                                                        

16:37 EX sensor correction off as the BRS was ringing up from Randys' loading of the ergo lift.

17:18 Sheila unlocked the rotation stage and I turned up the power to 1W, Sheila then relocked it.

17:35 UTC I used the ALS nodes to run an alignment for GRREN_ARMs, ALSX locked after a few taps of ETMX but ALSY took more convincing

19:30 UTC I started to run TFs for MC1, then MC3 aand RyanS did MC2

23:10 UTC SUSHB13 crashed, possible from Marc's work in a close by rack

23:17 UTC ITMX, ITMY WDs tripped, SW, ISI ST1, ISI ST2, and HEPI

23:31 I remeasured MC1 P and confirmed that the Coil Driver swap was unsuccessful, the TF still looked the same. I also ran an undamped OSEM spectra before and after the swap.

All the h1susb13 models stopped with timing errors this afternoon, followed later by h1psl0's iop model. CER activity was ongoing around this time.

We tried a model restart on h1psl0, which did not work. We rebooted the machine and all started OK.

We tried a reboot of h1susb13, but it got stuck. We then hard-reset the computer via IPMI and all came back OK.

Following the recovery of h1iopsusb13 I untripped the BSC1 and BSC3 SWWDs (the SEI had tripped).

Daniel had a new h1ascimc model to install (no DAQ restart). We stopped h1ascimc, which caused a DAC error on h1iopasc0. So as before, we had to restart all the h1asc0 models to load a new h1ascimc.

Per WP13076 we replaced the coil driver for MC1 due to suspicion it was causing MC1 to jump.  The coil driver in question glitched on TOP3.  Referencing D0902810-v12, the chassis in question is U41 on SUS-C4, we exchanged it with a spare.

Old SN - S1001097, New SN - S1100194

Shelia will retest the signal chain to see if this solves the issue.

FAMIS 38889, last checked in alog89213

There are 12 T240 proof masses out of range ( > 0.3 [V] )!
ETMX T240 2 DOF X/U = -1.784 [V]
ETMX T240 2 DOF Y/V = -1.829 [V]
ETMX T240 2 DOF Z/W = -1.089 [V]
ITMX T240 1 DOF X/U = -2.403 [V]
ITMX T240 1 DOF Z/W = 0.447 [V]
ITMX T240 3 DOF X/U = -2.587 [V]
ITMY T240 3 DOF X/U = -1.122 [V]
ITMY T240 3 DOF Z/W = -3.098 [V]
BS T240 3 DOF Z/W = -0.34 [V]
HAM8 1 DOF X/U = -0.301 [V]
HAM8 1 DOF Y/V = -0.439 [V]
HAM8 1 DOF Z/W = -0.746 [V]

All other proof masses are within range ( < 0.3 [V] ):
ETMX T240 1 DOF X/U = -0.045 [V]
ETMX T240 1 DOF Y/V = -0.067 [V]
ETMX T240 1 DOF Z/W = -0.059 [V]
ETMX T240 3 DOF X/U = -0.048 [V]
ETMX T240 3 DOF Y/V = -0.118 [V]
ETMX T240 3 DOF Z/W = -0.075 [V]
ETMY T240 1 DOF X/U = 0.032 [V]
ETMY T240 1 DOF Y/V = 0.17 [V]
ETMY T240 1 DOF Z/W = 0.232 [V]
ETMY T240 2 DOF X/U = -0.109 [V]
ETMY T240 2 DOF Y/V = 0.203 [V]
ETMY T240 2 DOF Z/W = 0.034 [V]
ETMY T240 3 DOF X/U = 0.244 [V]
ETMY T240 3 DOF Y/V = 0.057 [V]
ETMY T240 3 DOF Z/W = 0.108 [V]
ITMX T240 1 DOF Y/V = 0.293 [V]
ITMX T240 2 DOF X/U = 0.134 [V]
ITMX T240 2 DOF Y/V = 0.244 [V]
ITMX T240 2 DOF Z/W = 0.238 [V]
ITMX T240 3 DOF Y/V = 0.115 [V]
ITMX T240 3 DOF Z/W = 0.065 [V]
ITMY T240 1 DOF X/U = 0.02 [V]
ITMY T240 1 DOF Y/V = 0.142 [V]
ITMY T240 1 DOF Z/W = 0.012 [V]
ITMY T240 2 DOF X/U = 0.018 [V]
ITMY T240 2 DOF Y/V = 0.239 [V]
ITMY T240 2 DOF Z/W = 0.112 [V]
ITMY T240 3 DOF Y/V = 0.043 [V]
BS T240 1 DOF X/U = -0.06 [V]
BS T240 1 DOF Y/V = -0.286 [V]
BS T240 1 DOF Z/W = 0.208 [V]
BS T240 2 DOF X/U = 0.069 [V]
BS T240 2 DOF Y/V = 0.117 [V]
BS T240 2 DOF Z/W = 0.022 [V]
BS T240 3 DOF X/U = -0.132 [V]
BS T240 3 DOF Y/V = -0.259 [V]

There are 2 STS proof masses out of range ( > 2.0 [V] )!
STS EY DOF X/U = -4.566 [V]
STS EY DOF Z/W = 2.375 [V]

All other proof masses are within range ( < 2.0 [V] ):
STS A DOF X/U = -0.576 [V]
STS A DOF Y/V = -0.668 [V]
STS A DOF Z/W = -0.645 [V]
STS B DOF X/U = 0.124 [V]
STS B DOF Y/V = 0.96 [V]
STS B DOF Z/W = -0.355 [V]
STS C DOF X/U = -0.947 [V]
STS C DOF Y/V = 0.891 [V]
STS C DOF Z/W = 0.653 [V]
STS EX DOF X/U = 0.578 [V]
STS EX DOF Y/V = -0.515 [V]
STS EX DOF Z/W = -0.367 [V]
STS EY DOF Y/V = 1.166 [V]
STS FC DOF X/U = 0.155 [V]
STS FC DOF Y/V = -1.181 [V]
STS FC DOF Z/W = 0.633 [V]
 

Estimated Length Motion of the JAC

The calibrated error signal and feedback signal spectra were measured to estimate the free-running length motion of the JAC. Below the unity gain frequency (UGF = 400 Hz), the feedback signal represents the cavity length motion, while above the UGF the error signal represents the motion. The estimated length noise is well below the design assumption and does not appear to limit the JAC performance.

Method

The spectra of the calibrated error signal and feedback signal were measured to estimate the free-running length motion of the JAC.
- Below the UGF (400 Hz), the feedback signal represents the cavity length motion.
- Above the UGF, the error signal represents the cavity length motion.
Around 400 Hz, the spectrum appears slightly inflated because of the phase bubble, but the actual noise level is expected to be approximately flat in that region.

Observed Features in the Spectrum

- Above 30 Hz
Above 30 Hz, the spectrum becomes flat. This is likely not real cavity motion, but instead electronics noise from the readout chain. A more careful calculation is needed to identify the exact source, but it is most likely the photodiode or the ADC.
Since the incident power is currently 1 W, this noise floor is expected to decrease if the input power is increased.

- Below 10 Hz
Toward DC, the spectrum rises approximately with an f^-3 slope. This is interpreted as drift in the PZT control signal caused by temperature drift.
Therefore, the actual cavity length variation at low frequencies is expected to be smaller than what appears directly in the measured spectrum.

- Estimated Length Noise
Looking at the spectrum around 10 Hz, where the above effects are not expected to dominate, the cavity length noise is estimated to be approximately 2 × 10^-14 m/rtHz.
In the design, the cavity length motion was conservatively assumed to be 1 × 10^-12 m/rtHz at 10 Hz.
Therefore, the measured result is well below the design assumption, indicating that the loop design and the JAC do not introduce problematic intensity noise or phase noise.

Sanity Check with the FSS Unlocked

As a sanity check, the same measurement was repeated with the FSS unlocked. In this measurement, the vertical axis was converted into laser frequency noise by multiplying the calibrated length signal by
FSR / (lambda / 2)
where the free spectral range is given by
FSR = c / L
with c the speed of light and L the cavity round-trip length. For the JAC, L = 2.02 m.

The resulting spectrum, shown in the second plot, is approximately 100 Hz/rtHz at 100 Hz. This is consistent with the typical frequency noise of the NPRO laser.
This also confirms that the JAC is sufficiently quiet compared with the NPRO noise level.

Today we have been having some difficulty in locking the IMC, which might be related to MC1 an MC1 suspension problem.  

With the mode cleaner aligned and flashing, we checked the IMC REFL RF24 I and Q signals to check that the PDH phase looks OK, it does.  This is a similar amplitude to what we saw in trends from a time when the IMC was locking, here.  

WP13043 h1sush6 front end install

Daniel, Erik, Fil, Jonathan, Dave:

The new h1sush6 front end system is running with its full card complement and a basic IOP model.

On Wednesday afternoon we got the computer booting and seeing most of its chassis, detailed in alog 89376

The outstanding issues were: timing card was not receiving a timing signal, 4th Adnaco BP was not seen.

On Thursday we tracked the fibre issues to a not-quite-seated MTP on the MSR's MER patch (port 3). Once this fibre was reseated correctly the timing card received its signal and the 4th Adnaco BP was seen.

At this point I built up the IO Chassis with the correct card layout, using the ADC and 16bit-DACs provided by the BHD group. We supplied the Interface cards and ribbon cables from stock.

As of end-of-business Thursday the IO Chassis was almost complete, I had miscounted the 16bit-DACs and we were one card short. I built h1iopsush6 with this partial layout and we got the model running.

Friday lunch time I installed the 5th 16bit-DAC and added it to h1iopsush6. The system is now complete as-per drawings G2301306

H1SUSH6 IO Chassis Layout

This morning I went to the bifurcated laser hazard and adjusted alignment of the ALS SHG path on ISCT1, picking up where Jenne left off yesterday.  Drawing here

The IR beam was reasonably centered on the bottom periscope mirror and the 1" steering mirror right after it, it was clipping on the 1" BS used for the monitor PD.  I yawed the 1" mirror right after the periscope to reduce the clipping, seen on a card right after the BS.  Then I continued to yaw that first steering mirror to get a beam transmitted through the SHG, as you translate the beam you can see lots of glints transmitted which aren't the actual beam.  As soon as there was full beam going through the SHG, the green beam was alinged onto the COMM A broadband PD, so I didn't move any steering optics other than the first one.  

The monitor diodes do not agree with the power levels that they showed before the table move.  The IR one shows 6 times more power than before the table move, which makes me think the diode may not have been well aligned at the end of O4.  The beam in reflection off that first beamsplitter has two lobes visible on a card, possibly the front and back surfaces of the BS.  The beam was clearly missing the green power monitor PD, (before photo), I moved the diode to center, but the beam is still too low.  Nearly a year ago TJ and I wrote that this diode wasn't working, 84558, it does but seems to have been working since June 9th 2025, a day when the table was realigned as described in 84900. Since this alignment puts the beam onto the COMM diode, which is quite far from the SHG, I think it must be similar to previous alignments, and we probably need to adjust the height of this diode.

The power on the COMM A PD is about 300 counts, similar to what it was in O4.  So, this is probably a good enough alignment for us to proceed with locking with.  

Summary

The JAC length servo was designed to set the unity gain frequency (UGF) at 400 Hz. Additional low-frequency boost was implemented to improve suppression below 50 Hz. The open loop gain (OLG) was measured and compared with the servo model.

Details

• PZT actuator compensation

  The PZT driver has poles at 1 Hz and 400 Hz, and a zero at 10 Hz.
  To compensate for this response, a zpk(400, 10, 40) filter was implemented in the servo.
  With this compensation, the actuator response becomes approximately a first-order low-pass with a cutoff frequency of 1 Hz.

• Unity gain frequency

  The servo gain was then set so that the unity gain frequency (UGF) is 400 Hz.
  The phase margin at 400 Hz is 37 degrees, which includes the phase contribution from the first-order low-pass (90 degrees) and the additional phase delay in the system.

• Low-frequency boost

  A 1–50 Hz boost filter (first-order pole-zero boost filter) was implemented to improve low-frequency suppression.
  The phase contribution of this filter is –7 degrees at 400 Hz, resulting in a total phase margin of about 30 degrees at the UGF.
  Also, the integrater was implemented below 1Hz. Combination between boost and integrator gives f^{-2} slope below 50Hz.

• Open Loop Gain measurement

  The open loop gain (OLG) has been measured. A comparison between the measured OLG and the model is shown in the attached plot in the left panel. The right panel is the TF of the PZT.

• MEDM interface

  The OLG measurement template can be opened from the spectrum/OLG button in the bottom-right corner of the MEDM screen.

Summary

The calibration of the PDH error signal and the feedback path was derived using the Guardian-based signal normalization. The normalized PDH error signal allows the optical gain to be calculated analytically. The transfer function from L_SERVO_OUT to the cavity length actuation was measured and modeled, separating the optical gain and the PZT actuator response.

Details

Normalized PDH error signal

With the Guardian normalization, the PDH error signal at L_SERVO_IN1 can be written as
V = x / (1 + x^2)
where V is the signal at L_SERVO_IN1, and
x = l / HWHM
where l is the cavity length fluctuations and HWHM is the cavity half-width at half-maximum.

Using the finesse F, the cavity HWHM is
HWHM = lambda / (4F)

At the lock point (x = 0), the slope of the error signal is
dV/dx = 1

Optical gain

Therefore, the optical gain is
dV/dl = dV / d(x * HWHM) = 4F / lambda

Using F = 125, lambda = 1064e-9 m, the optical gain becomes
dV/dl = 4.70e8 cnts/m

Error signal calibration

To convert the signal at L_SERVO_IN1 to cavity length, we apply the inverse of the optical gain.
Calibration factor = 2.128e-9 m/cnts

Plant measurement

After locking the cavity with a provisional filter, the transfer function from L_SERVO_OUT to L_SERVO_IN1was measured and treated as the plant (see attached plot).
Since this plant includes both the optical gain dV/dl and the PZT actuator response, L_SERVO_IN1 was converted into meters using the calibration factor above before the measurement.
Also, the servo output is calibrated in V (and converted into cnts at the PZT_DRV filter). That means, the measured plant represents the transfer function from the PZT driver input to the actual cavity length actuation with the Unit of m/V

Plant model and actuator calibration

The optical gain and PZT actuator response are implemented in the servo model as FM9 and FM10 of L_SERVO.
In addition, a zpk(-800, 800) filter is included to emulate the phase delay.
The comparison between the model (FM9*FM10) and the measured plant (uncalibrated) is shown in the second plot. This response includes the PZT driver transfer function. That has two poles at 1 Hz and 400Hz, and one zero at 10 Hz. The DC gain estimated from the measured TF is 2.57 nm/V. This is comparable to the value measured with the scan of the JAC (2.97 nm/V).

Error signal normalization consistency

The error signal at JAC-L_SERVO_IN is normalized by the power at output of JAC_REFL_A_RF43. Therefore, once the guardian normalization procedure has been executed, the same calibration factor should remain valid.

I was adjusting the alignment of MC1 pitch earlier, when the suspension had a large alignment shift that wasn't caused by a change in the requested drive to the DACs.  The attached screenshot shows my requested alignment shifts in opticalign, and the resulting change in the requested DAC counts on T2 + T3.  There is a sudden 420 urad jump in the osem readbacks from pitch, and a 133 urad jump in roll at the first time cursor.  The master outs only see a few cycles on oscillations, which probably is from the damping loops responding to the jump, but they settle to the same requested drive as before the jump.  The jump seems to be real as the IMC flashes disappeared at this time.  

Jason and Jennie found that there's no digital signal coming out of JAC WFS DC no matter what.

I and Jason went to the floor, I flipped the gain switch of the WFS interface from low to high, but there was absolutely no response from any of H1:JAC-WFS_[AB]_SEG[1234]_INMON.

We confirmed that interface cables are connected from the IOT1 to the WFS interface (ISC-R1 slot U10), the interface is connected to the AA (ISC-C1 slot U30), and the AA chassis is connected to ADC5. These all agree with D1900511 floor wiring diagram. I even disconnected the cable coming to AA (ISC_373) and WFS DC signals didn't respond.

It seems that there's discrepancy between the floor wiring diagram and the model which was made according to T1100472 where JAC WFS DC signals are routed to ADC3 (see attached).

Good news is that RF channels are working.

As of now, the light is hitting WFSA and I was able to phase RF using an excitation injected into JAC PZT while JAC itself was locked. WFSB is dark now. 

(Travis S., Gerardo M.)
Pumpdown was started this morning, sorry no blowdown data.  By the time I remembered to take the reading there was no more pressure inside the chamber.  Travis connected all of the equipment while I wrestled with the viewport inspection.
Pumpdown was started without an issue.  We started with the scroll pump from the super sucker 500, the scroll pump of the SS500 cart brought the pressure down to 3.7x10-01 Torr, then we switched the cart to start pumping with the turbo pump/scroll pump.  We had one trip of the system, usually due to a time out, but it only took a restart of the turbo pump and the pumpdown to continue.
Unfortunately the pumpdown had to be stopped at 8:00 PM local time, with a pressure of 4.0x10^-05 Torr, at that pressure the set points had not activated on the SS500 cart controller, the set points are hard set and can't be modified from the SS500 controller screen.
Pumpdown will be restarted tomorrow morning.

Note, on the attachment, regarding the screens, no set points for channel 1.

The HAM1 +Y door was installed today.  Installation went smoothly and the O-ring cooperated by staying in place today.  I will note that torquing the door bolts is becoming more of an issue due to wrench access being increasingly limited near the 5-way cross/feedthru areas now that all the in-air cables have been attached.

The HAM1/HAM2 annulus system is being pumped by 2 turbos/aux carts on the -Y side of the chambers.  The mysterious ~order-of-magnitude pressure readout difference at the two carts on the shared annulus system is again present, as was noted the last time this annulus system was pumped down.  Not an issue per se, just some vacuum phenomena that leaves us scratching our heads. 

Now that HAM7 is at sufficient pressure (6.4E-7 Torr as of this post) we helium leak checked the two re-installed 12" CF blanks removed for table locking and the entire relay tube assembly which had been removed for the viewport adapter on HAM5.

The Helium background was unstable, so we turned on the HAM7 cleanroom (on 2/18 afternoon) to help flush the area of helium overnight.

Today the background stabilized around 1.5E-10 Torr-l/s, so we were able to continue leak checking. No significant helium signal observed above the leak detector background which hovered between 1.5&2E-10 Torr-l/s during leak checking. 

HAM7 continues to pump down with the turbopump, next steps are chamber RGA scans.