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ID Date Author Type Category Subject
14652   Tue Jun 4 00:17:15 2019 gautamUpdateBHDPreliminary BHD calculations

​Summary:

Attachment #1 shows the RIN and phase noise requirements for the 40m BHD for measuring Ponderomotive squeezing.

Some details:

1. The interferometer topology is not systematically optimized - I just picked values which are likely close to what we will eventually choose. Namely, $P_{\mathrm{PRM}} = 8\,\mathrm{W}$$\phi_{\mathrm{SRC}} = 0.275 ^{\circ}$$\zeta_{\mathrm{homodyne}} = 88 ^{\circ}$$\mathcal{L}_{\mathrm{rt}}^{\mathrm{arm}} = 30\, \mathrm{ppm}$$G_{\mathrm{PRC}}\approx 40$. Nevertheless, I think these requirements will not change by more than 30% for changes to the interferometer config.
2. The requirements are evaluated using the following criterion: assuming that the dominant noises are (i) coil driver at mid-frequencies and (ii) quantum noise at high frequencies, what do the RIN and phase noise on the LO have to be such that the equivalent displacement noise is a factor of 10 below? I opted for a safety factor of 10, this can be relaxed.
3. An unknown is how much contrast defect light we will end up having due to the mismatch between arms. I assumed a few representative values.
4. The calculations were done analytically. This paper provides a good summary of the relations - although my RIN requirement is more stringent because of the safety factor of 10, and phase noise requirement is less stringent (despite the same safety factor) because we plan to read out at nearly the amplitude quadrature.
5. Since we are discussing the possibility of delivering the LO field using a fiber-coupled pickoff of the laser prior to RF sidebands being added, these requirements do not benefit from passive filtering from the cavity transfer functions. Consequently, the requirements are pretty challenging I think.

Conclusions:

1. The RIN requirement looks very challenging - we will need a shot noise limited ISS with 100 mW DC sensing light, and will likely have to relax the safety factor depending on how much contrast defect light we end up having. This actually sets some requirement on the amount of filtering we need from the OMC (next step).
2. The phase noise requirement also looks very challenging - I need to look up what is possible with the double-pass through fiber technique.

Next steps:

1. Evaluate the pointing stability requirement on the LO field (IFO output is filtered by the OMC).
2. We still need to think of a control scheme for the LO phase - likely, I think we will need a suspended optic between the fiber collimator delivering the light to the BHD setup with some kind of length actuation capability.
3. Numerical validation of this analytic study. I believe Finesse is still missing some capabilities that allow us to calculate these couplings, but I'll ask the experts to be sure.
4. Build up the requirements on the OMC cavity:
• Backscatter requirement (related = OFI isolation requirement, relative length noise between SRM and OMC, OFI and SRM). Does the OFI also have to be suspended?
• Filtering requirement
• Pointing stability requirement
• Length noise requirement
14653   Tue Jun 4 10:56:31 2019 gautamUpdateIOOIMC diagnostics

I briefly managed to lock the IMC today - it stayed locked for ~10 minutes. Attachment #1 shows spectra of a few error and control signals for today's lock, and from a stretch yesterday before the problems surfaced*. The 60 Hz lines are much bigger, and MC_F signals broadband excess noise above a few Hz. I suspect a problem somewhere in the electronics.

*I confess the comparison isn't entirely valid because I had to tweak the FSS FAST gain from its nominal value of 22 to 25 in order to get the PC drive RMS down to the ~1.5V level. At the nominal gain setting, with the laser frequency locked to the cavity length, the PC Drive RMS was ~4 V. Still, indicative of something being off in the electronics.

14655   Tue Jun 4 23:41:13 2019 gautamUpdateCamerasSteps to interact with GigE

caget/caput probably does the job.

 Quote: Still not sure about how to modify the exposure time (other than using the pylon app, the only technique I know so far is to adjust the exposure manually on the medm screen and then run the scripts as described in the previous elog).
14658   Thu Jun 6 18:49:22 2019 gautamUpdateBHDPreliminary BHD calculations

Summary:

I did some more calculations based on our discussions at the meeting yesterday. Posting preliminary results here for comments.

Details:

Attachment #1 - Schematic illustration for the scattering scenarios. For all three scenarios, we would like for the scattered field to be lower than unsqueezed vacuum (safety factor to be debated).

Attachment #2 - Requirements on a fraction $\epsilon_{\mathrm{bs}} = 10 \, \mathrm{ppm}$ of the counter-propagating resonant mode of the OMC scattering back into the antisymmetric port, as a function of RIN and phase noise on this field (y-axis) and amount of field (depends on the amount of contrast defect light which can become resonant in the counter propagating mode). I don't encode any frequency dependence here.

Attachment #3 - Requirements on the direct scatter from the arm cavity resonant field (assumed to dominate any contribution from the PRC) onto the OMC DCPDs, for some assumed phase noise (y-axis) and fraction of the field that makes it onto the OMC DCPDs. This is a pretty stringent requirement. But the probability is low (it is the product of three presumably small numbers, (i) probablity of the beam scattering out of the TEM00 mode, (ii) BRDF of the scattering surface, (iii) probability of scattering back towards the DCPDs), so maybe feasible? I didn't model any RIN on this field, which would be an additional noise term to contend with. The range of the y-axis was chosen because I think these are reasonable amplitudes for chamber wall  / other scattering surface motion at acoustic frequencies.

14687   Sun Jun 23 08:09:53 2019 gautamUpdateIOONPRO diagnostics

Summary:

Over the last few days, I've been doing some (complementary) measurements to what Aaron and Koji have been looking at. The motivation was to identify if the problems we are seeing are optical (i.e. imprinted on the PSL light) or electronic. My findings:

1. 60 Hz line noise in PMC REFL and PMC TRANS is heavily dependent on whether I connect cables between the measuring PDs and Acromag ADC or not - but even with the Acromag cable disconnected, the 60 Hz RIN is HUGE - 10 mVpp out of 670 mV DC, and lines are much dirtier if you have connections to the SLOW ADCs. Measurement was made by looking at the time-domain signals on a battery powered Tektronix oscilloscope. See Attachment #1. I believe this line noise is higher it was. Cause is unknown to me at this point.
2. The NPRO noise eater seems to function as advertised. The measured RIN with the noise eater enabled (our nominal operating condition) is in line with what the manual tells us it should be. See Attachment #2.
3. There isn't strong evidence of excess frequency noise (measured with PLL) out to 100 kHz. I didn't measure the high-frequency part yet, but maybe I'm doing something wrong with the PLL setup which should be first corrected. See Attachments #3, #4.
4. The beat note frequency between the free-running PSL and EX NPRO's is definitely slewing more than the quadrature sum of the advertised 1 MHz/min slewing per the manual.

Evidence:

Attachment #1: Time domain look at PMC Refl and Trans signals under various operating conditions. During this work, I took the chance to remove ~4 BNC T connectors that were connected on the PMC TRANS photodiode (Thorlabs). Now, there is one cable going to the Acromag ADC, and one going to the Oscilloscope used to monitor these signals. Any further T-ing can be done at the oscilloscope.

Attachment #2: RIN measurement of the NPRO light. I opted to place a Thorlabs PDA55 in the IR ALS pickoff light path. This is before the light sees the PMC. A DC block was inserted between the PDA55 and the AG4395 used to make the measurement. DC level of the PD output was 3.1 V into high-Z and I used half this value to normalize the measurement made by the 50-ohm input AG4395 into RIN units. The measurement was made with the PZT and slow temperature controls to the NPRO connected/disconnected, but I saw no significant difference.

Attachment #3: Frequency noise measurement via PLL. This shows the loop transfer funtion for the PLL. Some details of the setup:

• The beat note for locking the PLL was made between the PSL NPRO and the EX NPRO (output of the IR ALS BeatMouth). ~4dBm beatnote.
• Local oscillator was sourced by a Marconi, f_carrier=33 MHz, RF level = +10dBm.
• Level 7 Mixer and LB1005 controller from the mode-spectroscopy PLL setup.
• PLL control signal routed to EX NPRO PZT via Heliax cable running along south arm.
• Why EX and not PSL or Marconi FM? Latter has limited range, ~1/10th of that offered by NPRO PZT. PSL PZT has a 2.9 Hz corner freq Pomona box. I could disconnect this for the purpose of PLL locking, but I thought it may be interesting to see if there’s any hints of the problem being electrical, by looking at PLL spectra with / without Pomona box. The expected delay due to cabling is only 400 ns, so not really a limiting factor for the PLL bandwidth.
• LB 1005 settings:
• PI corner = 3 kHz.
• G = 2.30 (I could not increase this further - with the PSL+Lightwave NPRO PLL, we could achieve a UGF of ~60 kHz, but in this setup, I can't do much better than ~7kHz before the loop starts oscillating, not sure if the fact that the PZT actuation coefficient for the Innolight is ~5x lower than for the Lightwave is enough to explain this?).
• LFGL = 90 dB.
• Mixer output had a maximum value of 800 mVpp => PLL discriminant is 400 mV/rad.
• The "eye fit" is just the transfer function of two poles at DC (one for frequency to phase conversion in the PLL and one for the LB1005 integrator), and a zero at 3kHz (PI corner). I scaled the gain till the "fit" and measurement lined up, and then used this model to undo the loop suppression of the error signal to extract the frequency noise without worrying about the frequency vector of the measurement being limited.
• Once again, slow temperature control and PZT controls to the PSL NPRO were disconnected so this measurement was made with two free-running NPROs.

Attachment #4: Frequency noise measurement via PLL. This shows the frequency noise. I've overlaid the expected frequency noise between 2 free-running NPROs, model used is in the text box in the plot. There isn't strong evidence of excess high frequency noise in this measurement. The fact that the "LB 1005 input terminated" trace is below all the others supports the hypothesis that I'm measuring real frequency noise. The bump around a few kHz could indicate some gain peaking?

However, I'm unable to find good agreement between the measured frequency noise using the error point and the control point. For the former, I used the PLL discriminant mentioned above of 400 mV/rad, and undid the loop suppression, and for the latter I used a PZT discriminant of 1.7 MHz/V. However, there is still a constant scale difference between these two traces. So I'm doing something wrong?

Next steps:

1. More interpretation of the PLL measurement results required.
2. Measure the PLL error signal spectrum to higher frequencies using the AG4395.
3. ???

I've not disturbed the PLL setup in case anyone else wants to repeat these measurements, but I have restored the normal electrical connections to the PSL PZT and temperature control.

Some other activity:

1. Alignment into the PMC was tweaked.
2. NPRO laser pump current was increased from 1.9 A to 2.0 A.
3. PMC servo gain was changed from +18 to +17 to prevent the servo from oscillating.
14688   Sun Jun 23 09:36:32 2019 gautamUpdateIOOIMC is locking normally again

After typing up the elog, I decided to try locking the IMC again - now it locks again with the "OLD" gain settings. I tested it ~5 times, the autolocker brings the lock back and the PC drive levels are normal. IMC transmission and MC REFL DC light levels in lock are normal. The PC Drive RMS voltage is <1V. What's more, there is no longer any evidence of 60 Hz line harmonics any more in the PMC diagnostics channels. Compare attachment #1 to this elog.

WTF.

I undid the changes Koji made to the autolocker gains, and am trying the old settings again. Let' see how stable or otherwise the config is. I must've jiggled some poor cable connection back into a good spot while working on the PSL table?

Anyway, this helps Kruthi and Milind.

14690   Mon Jun 24 08:12:10 2019 gautamUpdateIOOIMC is locking normally again

Over the last 24 hours, the IMC autolocker was able to keep the MC locked ~60% of the time. This is not particularly good, but is an improvement on ~2 weeks ago when the IMC couldn't be locked.

There are two periods, which I've indicated by vertical cursors, between which the autolocker was doing something strange - usually this kind of trend is caused by one or more of the VME crates being unresponsive and the autolocker gets stuck, but I confirmed that both c1psl and c1iool0 are telnet-able. So I conclude that the stability and reliability of the IMC loop is still not as good as it used to be.

Note also that while the PC drive RMS level mostly hovers around 1 V, there are several excursions above that level. This in itself isn't a new phenomenon. I will do some more characterization by measuring the in-loop error signal spectrum and maybe the OLTF of the IMC locking loop.

 Quote: Let' see how stable or otherwise the config is. I must've jiggled some poor cable connection back into a good spot while working on the PSL table? Or the NPRO decided to be less noisy on Sunday.
14691   Mon Jun 24 11:48:35 2019 gautamUpdateIOOIMC in-loop error spectra and OLTF

Attachment #1 - In loop error spectra, measured as Koji posted end of last week.

• Main difference is that the line noise seems much lower.
• For the "dark" measurement, I set the IN1 gain of the servo board to the value of +4 dB, which is what it is in lock.
• As Koji mentioned, this isn't an apple-to-apple comparison as the IMC loop will squish the plotted orange trace.
• Nevertheless, the fact that the blue trace is above orange everywhere gives confidence that we are in fact measuring frequency noise.
• For the higher frequency measurement, I used the AG4395 analyzer, which has 50 ohm input impedance. So to get the measurements with the SR785 to line up, I multiplied these by x2.
• For the frequency axis calibration, I used the value of 13 kHz/V for the PDH discriminant, which was what I measured it to be last year (but I didn't check again today).
• Note that the IMC locking loop OLTF has not been undone, so this isn't the actual laser frequency noise on the transmitted beam. In order to measure the latter, we'd have to use (for example) an arm cavity as an analyzer.

Attachment #2 - OLTF of the IMC loop.

• Measurement was made using the IN1/IN2 method, injection was done at the "A EXC" front panel BNC input.
• For comparison, I've overlaid a measurement from the 2017 IMC loop investigations. Doesn't seem to be significantly different.
• UGF and phase margin are in the ballpark of what they were reported to be in the past.

Attachment #3 - Photo courtesy Koji showing the bank of BNC connectors used for these measurements.

Clearly, these measurements were taken in a time when the IMC was "well behaved". How to characterize what's happening when this isn't the case?

14696   Tue Jun 25 15:32:16 2019 gautamUpdateIOOPMC and IMC locked again, some MEDM maintenance

Aaron complained to me earlier that the PMC could not be locked. Turned out to be a classic sticky slider problem, I keyed the c1psl VME crate, and did the usual burtrestore trick. After that, I could immediately lock the PMC and IMC with the nominal gain settings.

I also looked at the wiring at the rack. An SLP250 was installed at the mixer IF output, in parallel with a 50 ohm terminator to ground. I removed this, because as Aaron pointed out, the PMC servo card "FP1 TEST" input is already 50 ohm, and has two cascaded LC filter stages immediately after to filter out the 2f component, so the extra low-pass filtering is superfluous (in any case, 250 MHz is much too high a cutoff to be using for cutting out the 2f component which will be at ~70 MHz).

Finally, in the last ~2 weeks, we have been running with the PMC servo gain of +17 (as opposed to +18 from before). The old gain is too high, as noted by Milind. But the MEDM field for this gain goes RED unless the gain is +18. I adjusted the value of the  C1:PSL-STAT_PMC_NOM_GAIN channel to +17, so that this is no longer the case. I also edited the PMC MEDM screen to get rid of my comment that the "SLOW ADC IS DEAD" for the PMC TRANS field, since I have now hooked up the PMC trans photodiode to our temporary Acromag box.

14703   Wed Jun 26 20:45:03 2019 gautamUpdateCamerasField of view options

For the beam spot position tracking, I am wondering if there is any benefit to going for a wider field of view and getting the OSEMs in the frame? It may provide some "anchor points" against which whatever algorithm can calibrate the spot position against. But there are also several point scatterers visible in the current view, and perhaps the Gaussiam beam profile moving over them and tracking the scattered intensity from these point scatterers serves the same function? I don't know of a good solution to have a "switchable" field of view configuration in the already cramped camera enclosure though.

Also, I think it may be useful to have a cron job take a picture of MC2 and archive it (once a week? or daily?) to have some long term diagnostic of how the scattered light received by the camera changes over several months.

 Quote: The GigE is focused now and I have closed the lid. I'm attaching a picture of the MC2 beam spot, captured using GigE at an exposure time of 400µs
14704   Wed Jun 26 21:01:26 2019 gautamUpdateLSCPOX and POY locking

Now that the IMC is remaining locked for extended periods of time, the next problem to attack is the ASS dither alignment system. For a start, I decided to try and get the POX and POY locking working again, as we have not fully recovered the interferometer alignment after the most recent pumpdown. I spent a couple of hours tweaking the alignment of the arm cavity mirrors, BS, and TTs to try and recover the maximum possible TRX and TRY - however, my best efforts only yielded TRX~0.8, TRY~0.75. Moreover, the beam axis is such that the spot is significantly off in YAW on both ETMs, as evidenced by the camera views (also true but less obvious on the ITMs). However, trying to bring the beam back to the center of the optics yields TRY and TRX values lower than the above reported maxima. The EX green beam is currently unavailable to verify the arm cavity alignment because of my hijacking the EX NPROs PZT control for PLL investigations, but with the Y arm, I'm able to lock a TEM00 mode. Probably just needs more careful systematic alignment, but I'm not pursuing this tonight.

14705   Thu Jun 27 14:28:12 2019 gautamUpdateLSCPOX and POY locking

After a more systematic alignment effort, I was able to get the spots better centered on the optics (judged by eye from the analog camera views). TRY ~0.7, TRX~1.15. The X-arm dither alignment system seems to work out-of-the-box with the existing settings, I was able to run it and maximize the X-arm transmission.

Other work: I also cleaned up the area around MC2 a litte - laptop from on top of the vacuum chamber was removed and a rogue ethernet cable was also removed. The resulted in some misalignment of the IMC, which I corrected by manual alignment. Now the IMC is locked again with nominal transmission levels.

On the PSL table, I re-routed the RF output from the BeatMouth to the regular IR-ALS electronics chain (it was hijacked for PLL investigations). At EX, I disconnected the cable running from the LB1005 to the EX NPRO laser PZT (again was being used for PLL locking), and re-connected the output from the Green uPDH box to allow for some ALS tests to be done. I could then lock the EX green beam to the X-arm, and achieved GTRY ~ 0.35 using the ASX system. More to follow on ALS tests later today.

14716   Mon Jul 1 20:27:44 2019 gautamUpdateASCASX tuning

Summary:

To practise the dither alignment servo tuning, I decided to make the ASX system work again (mainly because it has fewer DoFs and so I thought it'd be easier to manage). Setup is: dither PZT mirrors on EX table-->demodulate green transmission at the dither frequencies-->Servo the error signals to 0 by an integrator.

Details:

1. Started by checking the dither lines are showing up with good SNR in GTRX. They are, see Attachment #1. The dither lines are at 18.23 Hz, 27.13 Hz, 53.49 Hz and 41.68 Hz, and all of them show up with SNR ~100.
2. Hand-aligned the beam till I got a maximum of GTRX ~ 0.35. This is lower than the usual ~0.5 I am used to - possibilities are (i) in the process of plugging in the BNC cable to the rear of the EX laser for my PLL investigations, I disturbed the alignment into the SHG crystal ever so slightly and I now have less green light going into the cavity or (ii) there is an iris on the EX table just before the green beam goes into the vacuum on which it is getting clipped. IIRC, I had centered the GTRX camera view such that the spot was well centered in the field of view, but now I see substantial mis-centering in pitch. So the cavity alignment for IR could also be sub-optimal (although I saw TRX ~1.15). Anyways, I decided to push on.
3. Introduced a deliberate offset in a given DoF, e.g. M1 PIT. Then I looked at the demodulated error signals (filtered through an RLP0.5 filter post demodulation, so the 2f component should be attenuated by 100 dB at least), and tuned the demod phase until most of the signal appeared in the I-phase, which is what is used for servoing. The Q-phase signals were ~x10 lower than their I-phase counterparts after the tuning.
4. Checked the linearity of the error signal in response to misalignment of a given DoF. I judged it to be sufficiently linear for all four DoFs about the quadratic part of the GTRX variation.
5. Tweaked the overall servo gains to have the error signals be driven to 0 in ~10 seconds.
6. There was quite significant cross-coupling between the DoFs - why should this be? I can understand the PIT->YAW coupling because of imperfect mounting of the PZT mounted mirror in a rotational sense, but I don't really understand the M1->M2 coupling.
7. Nevertheless, the servo appears to work - see Attachment #2.

The adjusted demod phases, servo gains were saved to the .snap file which gets called when we run the "DITHER ON" script. Also updated the StripTool template.

I plan to repeat similar characterization on the IR dither alignment servos. I think the tuning of the ASS settings can be done independently of figuring out the mystery of why the TRY level is so low.

14718   Tue Jul 2 12:30:53 2019 gautamUpdateElectronicsAcromag crate switched to Sorensens

[chub, gautam]

We crossed off another couple of bullets today.

It took me ~1 hour to realize that c1susaux requries the running of sudo /sbin/ifup eth0 to be run in order to see the martian network - why???

Activity:

1. Stopped the c1susaux machine:
• Moved alignment sliders of ITMX and ITMY to 0 as a precaution.
• Shutdown the c1susaux machine so that it doesn't become unhappy with the missing Acromags when we power the unit down.
2. Dialled down supply voltages on the +/- 15 V and +/- 20 V DC Sorensens. Current draw became 0 A on the front panel indicators.
3. Chub tapped some new terminal blocks for +15 V DC and +20 V DC
• This required some additional daisy chaining, which is why we dialled down the Sorensens.
• New cables were made using the "standard" LIGO color scheme, which isn't really applicable in this case because we are using +15 V DC (orange sheath wire) and + 20 V DC (yellow sheath wire) whereas the closest LIGO standard voltages are +18 V DC and +24 V DC.
• A test cable, presumably meant to be used in the electronics area (orange for +15 V DC) was destroyed for this work as we opted for speed rather than making a new cable.
4. Disconnected bench power supplies that were powering the Acromags, and connected the new cables.
• I opted to use 5 A fuses in the terminal blocks for these supplies as the current draw is pretty significant.
5. Dialled the Sorensens back up to the nominal voltages:
• Attachment #1 shows the front panels of the Sorensens before and after this work.
• The current limit on the +20 V DC Sorensen had to be raised, because the Acromag box draws ~2.3 A on its own, whereas the previous current draw was 2.8 A.
6. Brought the c1susaux machine back online. Took me a while to get to the bottom of why I wasn't able to see c1susaux on the martian, but eventually, I figured out the whole sbin/ifup thingy.

I don't understand the exact chain of causation, but during this work, the fast c1sus model crashed. I had to go through a few iterations of the scripted vertex machine rebooting, but things seem to be back in a normal state now, see Attachment #2. Should probably run the IFO test suite to make sure everything is a-okay, but for now, I am able to lock the IMC so I'm moving on.

The main task remaining here is to take new pictures of everything and upload to the wiki. Also, need to update the Sorensen labels to reflect their current values, some of them are outdated.

 Quote: Take photos of the new setup, cabling. Remove the old c1susaux crate from the rack to free up space, possibly put the PSL monitoring acromag chassis there. Test that the OSEM PD whitening switching is working for all 8 vertex optics.(verified as of 5/3/19 5pm) New 15V and 24V power cables with standard LIGO connectors need to be run from the Sorensenn supplies in 1X5. The chassis is currently powered by bench supplies sitting on a cart behind the rack. All 24 new DB-37 signal cables need to be labeled. New 96-pin DIN connectors need to be put on two ribbon cables (1Y5_80 B, 1Y5_81) in the 1X4 rack. We had to break these connectors to remove them from the back of the eurcrates. General cleanup of any cables, etc. left around the rack. We cleaned up most things this evening. Rename the host computer c1susaux2 --> c1susaux, and update the DNS lookup tables on chiara.
14719   Tue Jul 2 16:57:09 2019 gautamUpdateCDSc1sus is flaky

Since the work earlier this morning, the fast c1sus model has crashed ~5 times. Tried rebooting vertex FEs using the reboot script a few times, but the problem is persisting. I'm opting to do the full hard reboot of the 3 vertex FEs to resolve this problem.

Judging by Attachment #1, the processes have been stable overnight.

14720   Tue Jul 2 17:34:54 2019 gautamUpdateLSCIrides opened up on EY table

In preparation for the ASS debugging, I decided to check out the beam path on the EY table. In order to be able to do this, I had to setup the POY locking to trigger on AS110 instead of TRY (as is usual for this kind of debugging). Then I could poke an IR card in the beam path without destroying the lock.

There are two irides in the beam path immediately between the vacuum window and the harmonic separator that splits off the IR and green beams. I found that the beam was in fact getting clipped on both of them. It was also somewhat off center on a 2" beamsplitter that sends half of the light to the QPD (currently decommissioned). The purpose of these irides are (I think) to eliminate some ghost reflections of the green beam and also the Oplev beam. I opened up the irides until I felt that there wasn't any more clipping of the IR beam, but the appropriate ghost beams were still getting caught.

I also re-aligned the beam onto the TRY Thorlabs PD so as to better center it on the active area. In summary, the result of this work was that the TRY level went from ~0.6 to ~0.93. There may still be some scope for optimizing this - I tried running the Y-arm ASS scripts, and already, the loops don't run away any more. I'll do the systematic analysis of the servo anyways. But given that the IMC Trans lev el used to be ~15,500 counts and is now ~14,500 counts, I think ~7% drop in TRY level is in line with what we "expect" (assuming the pre-power-degradation TRY level was 1.000).

Note that these irides were installed (I think) by Yuki, and so cannot explain the ASS anomalies of July 2018 (i.e. it does not exonerate in-vacuum clipping of the beam, as Koji had already verified that the in-air path was clean back then).

14722   Wed Jul 3 11:47:36 2019 gautamUpdateBHDPRC filtering

A question was raised as to how much passive filtering we benefit from if we pick off the local oscillator beam for BHD from the PRC. I did some simplified modeling of this. For the expected range of arm cavity round trip losses (20-50 ppm), I think that the 40m CARM pole will be between 75-85 Hz. The corresponding recycling gain will be 40-50, with the current PRM. I assumed 1000 ppm loss inside the PRC. The net result is that, assuming the single pole coupled cavity response, we will get ~8-9 dB of filtering at ~200 Hz of the intensity noise of the input laser field to the interferometer if we pick the LO beam off from the PRC (e.g. PR2 transmission), instead of picking it off before.

The next questions are: (i) can we do a sufficiently good job of achieving the required RIN stability on the LO field for BHD without relying on the passive filtering action of the PRC? and (ii) is the benefit of the PRC filtering ruined in the process of routing the LO field from wherever the pickoff happens to the BHD setup?

14736   Tue Jul 9 08:33:31 2019 gautamSummarySUSETMX PIT bias voltage changed by ~1V

After this activity, the DC bias voltage required on ETMX to restore good X arm cavity alignment has changed by ~1.3 V. Assuming a full actuation range of 30 mrad for +/- 10 V, this implies that the pitch alignment of the stack has changed by ~2 mrad? Or maybe the suspension wires shifted in the standoff grooves by a small amount? This is ~x10 larger than the typical change imparted while working on the table, e.g. during a vent.

Main point is that this kind of range requirement should probably be factored in when thinking about the high-voltage coil driver actuation.

 Quote: We unstuck ETMX by shaking the stack. Most effective was to apply large periodic human sized force to the north STACIS mounts.
14738   Tue Jul 9 18:06:05 2019 gautamUpdateLSCY-arm ASS in a workable state

The Y-arm ASS was tuned to be in a workable state. Basically, I followed Koji's recipe.

The SNR of the dither lines in the TRY and YARM control signals were checked - Attachment #1. The dither frequencies are marked with vertical dashed lines (can't figure out how to add 4 cursors in DTT so there's two in each row for a total of 4). A couple of days ago, when I was doing some preliminary checks, I found that the oscillator at 24.91 Hz caused a broadband increase in the TRY noise between DC and ~100 Hz. But today I saw no evidence of such behaviour. So I decided against changing the frequency.

The linearity of the demodulated error signals around the quadratic maxima of the TRY level was checked. I did not, however, investigate in detail the frequency-dependent offset Koji has reported in his elog.

After this work, the TRY level is at 0.95. This is commensurate with the MC trans level being lower by ~7% relative to July 2018. Furthermore, the ASS servo is able to return to TRY~0.95 with a time-constant of ~5 seconds in response to misalignment of the cavity optics. After I investigate the X-arm ASS, I will reset the normalization for TRX and TRY.

Update 645pm: In the spirit of general IFO recovery, I re-centered the ITM and ETM oplev spots, and also the IR beam on the IPPOS QPD to mark the new input pointing alignment (the spot is slightly lower on the AS camera than what I remember). I then tweaked the XARM transmission to maximize it, and re-set the TransMon normalization. I edited the normalization script to comment out the normalizing of the TransMon QPD gains as the QPDs are in some kind of indeterminate state now. Attachment #2 shows the current status, you can also see the normalization being reset. LSC mode disabled for overnight.

Once the XARM ASS is also checked out, I propose moving back to locking the DRMI / PRFPMI configs.

14739   Tue Jul 9 18:17:48 2019 gautamUpdateGeneralProjector lightbulb blown out

Last documented replacement in Nov 2018, so ~7 months, which I believe is par for the course. I am disconnecting its power supply cable.

14740   Tue Jul 9 18:42:15 2019 gautamUpdateALSEX green doubling oven temperature controller power was disconnected

There was no green light even though the EX NPRO was on. I checked the doubling oven temperature controller and found that its power cable was loose on the rear. I reconnected it, and now there is green light again.

14742   Wed Jul 10 10:04:09 2019 gautamUpdateSUSTip-Tilt moved from South clean cabinet to bake lab cleanroom

Arnaud and I moved one of the two spare TT suspensions from the south clean cabinet to the bake lab clean room. The main purpose was to inspect the contents of the packaging. According to the label, this suspension was cleaned to Class A standards, so we tried to be clean while handling it (frocks, gloves, masks etc). We found that the foil wrapping contained one suspension cage, with what looked like all the parts in a semi-assembled state. There were no OSEMs or electronics together with the suspension cage. Pictures were taken and uploaded to gPhoto. Arnaud is going to plan his tests, so in the meantime, this unit has been stored in Cabinet #6 in the bake lab cleanroom.

14745   Wed Jul 10 16:53:22 2019 gautamUpdateSUSPRM watchdog condition modified

[koji, gautam]

We noticed that the PRM watchdog was tripping frequently. This is a period of enhanced seismic activity. The reason PRM in particular trips often is because the SIDE OSEM has 5x increased transimpedance. We implemented a workaround by modifying the watchdog tripping condition to scale the SD channel RMS by a factor of 0.2 (relative to the UL and LL channels). We restarted the modbus process on c1susaux and tested that the new logic works. Here is the relevant snippet of code:

# Disable fast DAC if variation tests too high
# PRM Side is special, see elog 14745 record(calc,"C1:SUS-PRM_LOGIC") {     field(DESC,"Tests whether RMS too high")     field(SCAN,"1 second")     field(PHAS,"1")     field(PREC,"0")     field(HOPR,"1")         field(LOPR,"0")         field(CALC,"(A<B)&(C<B)&(0.2*D<B)")         field(INPA,"C1:SUS-PRM_ULPD_VAR  NPP  NMS")         field(INPB,"C1:SUS-PRM_PD_MAX_VAR  NPP  NMS")         field(INPC,"C1:SUS-PRM_LLPD_VAR  NPP  NMS")         field(INPD,"C1:SUS-PRM_SDPD_VAR  NPP  NMS") }

The db file has a note about this as well so that future debuggers aren't mystified by a factor of 0.2.

14747   Thu Jul 11 12:42:35 2019 gautamSummaryCDSP2 interface board

I looked into the design of the P2 interface board. The main difficulty here is geometric - we have to somehow accommodate sufficient number of D-sub connectors in the tight space between the two P-type connectors.

I think the least painful option is to stick with Johannes' design for the P1 connector. For the CM board, the P2 connector only uses 6 pairs of conductors for signals. So we can use a D-15 connector instead of 2 D-37 connectors. Then we can change the PCB shape such that the P1 connector can be accommodated (see Attachment #1). The other alternative would be to have 2 P-type connectors and 3 D-subs on the same PCB, but then we have to be extra careful about the relative positioning of the P-type connectors (otherwise they wont fit onto the Eurocrate). So I opted to still have two separate PCBs.

I took a first pass at the design, the files may be found here. I just auto-routed the connections, this is just an electrical feedthrough so I don't think we need to be too concerned about the PCB trace routing? If this looks okay, we should send out the piece for fab ASAP.

I will work on putting together the EPICS server machine (SuperMicro) this afternoon.

 Quote: 2. D040180 / D1500308 Common Mode Board CM servo board itself doesn't need any modification. The CM board uses P1 and P2. So we need to manufacture a special connector for CM Board P2. (cf The adapter board for P1 T1800260). See also D1700058.
14753   Thu Jul 11 17:58:38 2019 gautamUpdateEquipment loanTT suspension --> Downs

Arnaud has taken 1 TT suspension from the 40m clean lab to Downs for modal testing. Estimated time of return is tomorrow evening.

14754   Thu Jul 11 18:15:22 2019 gautamSummaryElectronicsPSL/IOO rack checkout

I looked at the PSL/IOO racks to check for which boards, if any, require an additional P2 interface, so that we can try and design a generic one for the IMC/CM boards and whatever else may require it. While searching the elog, I saw that Koji and Johannes had already done this, see Koji's elog in this thread. Some remarks:

1. D990155 seems to be unused in both PSL and IOO racks. The one in the PSL rack has some LEMO cables plugged in to the front panel, but they go nowhere. So I think that both of these are redundant (in the assessment below, only one was marked redundant).
2. In the PSL rack, the "TTFSS Interface", "PSL PMC SERVO", and "DAQ INTERFACE" (which I think is obsolete) cards all have their P2 connectors daisy chained together, going to a cross-connect. Kruthi and I traced this to be going to a cross connect marked "J23-PSLRACK-CCP". In the PSL wiring diagram of which we have a hardcopy in the control room, it looks like these channels are related to the RefCav? So I think this is not required to be interfaced to our new Acromag DAQ system.

Conclusion: Only the IMC Servo and CM boards need their P2 connectors connected to Acromag.It would be helpful to remove the TTFSS Interface board and figure out what exactly the pin-mapping for the backplane connectors are, but I didn't do this today because there is a "High Voltage" line going to the Interface Board and I'm not actually sure of the signal chain for the FSS servo.

14755   Fri Jul 12 07:37:48 2019 gautamUpdateSUSM4.9 EQ in Ridgecrest

All suspension watchdogs were tripped ~90mins ago. I restored the damping. IMC is locked.

ITMX was stuck. I set it free. But notice that the UL Sensor RMS is higher than the other 4? I thought ITMY UL was problematic, but maybe ITMX has also failed, or maybe it's coincidence? Something for IFOtest to figure out I guess. I don't think there is a cable switch between ITMX/ITMY as when I move the ITMX actuators, the ITMX sensors respond and I can also see the optic moving on the camera.

Took me a while to figure out what's going on because we don't have the seis BLRMS - i moved the usual projector striptool traces to the TV screen for better diagnostic ability.

Update 16 July 1515: Even though the RMS is computed from the slow readback channels, for diagnosis, I looked at the spectra of the fast PD monitoring channels (i.e. *_SENSOR_*) for ITMX - looks like the increased UL RMS is coming from enhanced BR-mode coupling and not of any issues with the whitening switching (which seems to work as advertised, see Attachment #3, where the LL traces are meant to be representative of LL, LR, SD and UR channels).

14762   Mon Jul 15 18:55:05 2019 gautamUpdateIOOMegatron hard-rebooted

[koji, gautam]

In addition to c1psl needing a reboot, megatron was un-ssh-able (although it was responding to ping). Clue was that the NPRO PZT control voltage was drifting a lot on the StripTool trace. Koji hard-rebooted the machine. Now IMC is locked, and FSS slow servo is also running.

14763   Tue Jul 16 15:00:03 2019 gautamUpdateSUSMultiple small EQs

There were several small/medium earthquakes in Ridgecrest and one medium one in Blackhawk CA at about 2000 UTC (i.e. ~ 2 hours ago), one of which caused BS, ITMY, and ETM watchdogs to trip. I restored the damping just now.

14765   Tue Jul 16 16:00:01 2019 gautamUpdateCDSc1iscaux Supermicro setup

I worked on preparing for the c1iscaux upgrade a bit today.

1. Attachment #1: This shows where the 120 GB solid-state hard-drive and the 2 RAM cards (2GB each) are installed.
• I found that it required considerable application of force to get the RAM cards into their slots.
• Note: the 4GB RAM is broken up into two separate physical cards, each 2GB. The labeling is a bit confusing, as each card suggests it is by itself 4GB.
2. OS install for c1iscaux:
• I followed Jon's instructions (and added some of mine to the wiki page to hopefully make this process even less thinking-intensive).
• To be able to use the IP address 192.168.113.83, removed "bscteststand" from chiara martian.hosts and rev.113.168.192.in-addr.arpa as the last mention I could find of this machine was from 2009 (and I'm pretty sure it isn't an active unit anymore). I then restarted the bind9 process.
• The hostname for this machine is currently "c1iscaux3" for testing purposes, I will change it once we do the actual install.
• There was an error in the installation instructions to allow incoming ssh connections - it is openssh-server that is required, not openssh-client. This has now been fixed on the wiki page instructions.
3. Acromag static IP assignment:
• Assigned 2 ADCs (XT1221), 5 DACs (XT1541) and 5 sinking BIO units (XT1111) static IP addresses (and labelled them for easy reference) using the windows laptop and the Acromag IP config utility.
• I saw no reason not to use the 192.168.114.yyy scheme for the Acromag subnet on this machine, even though c1auxex and c1vac both have subnets with this addressing prefix. For reasons unknown to me, Jon opted to use 192.168.115.yyy for the c1susaux Acromag subnet.
4. Followed the excellent step-by-step to install EPICS, Modbus and Asyn.
• This took a while, ~1 hour, dominated by the building of EPICS. The other two took only a couple of minutes each.
• The same combination suggested on Jon's wiki, of Modbus R2-11, EPICS base-7.0.1 and asyn4-33, are the most current at the time of installation.
• Couple of typos that prevented straight up copy-pasting were fixed on the wiki.
5. Playground for testing new database files:
• made a directory /cvs/cds/caltech/target/c1iscaux3 and copied over the .db files from /cvs/cds/caltech/target/c1iscaux and /cvs/cds/caltech/target/c1iscaux2 over.
• Johannes said he did not develop any code to automate the process of translating the old .db files into the new ones for the Acromag - I won't invest the time in developing any either as I think just manually editing the files will be faster.
• I think I will follow the c1susaux convention of grouping .db files by the physical electronics system where possible (e.g. REFL11 channels in one file, CM channels in one file etc), as I think this makes for easier debugging.
• There is an old "PZT_AI.db" file which I think consists completely of obsolete channels.
6. Next steps:
• Wire up the crate [Chub]
• Make the database files and modbus files for talking to the Acromags on the internal subnet [Gautam], check the .db files [Koji]
• Wiring of whitening switching from P1 to P2 connector, Issue #1 in this elog (this will also requrie the installation of the DIN shrouds) [Koji]
• Soldering of P2 interface boards [Gautam]
• Bench testing [Gautam, Koji, Chub]
• Installation and in-situ testing [Gautam, Koji, Chub]

All the required additional parts should be here by the end of the week - I'd like to aim for Wednesday 7/24 for the installation in 1Y3 and in-situ testing. While talking to Rana, I realized that we should also factor in the c1aux slow channels into this acromag crate - there is no need for a separate machine to handle the shutters and illuminators. But let's not worry about that for now, those channels can simply be added later.

14769   Wed Jul 17 21:22:41 2019 gautamUpdateCDSCM board Latch Enable subtlety

[koji, gautam]

Koji pointed out an important subtlety pertaining to the "LATCH ENABLE" signal line on the CM board. The purpose of this line is to smoothly facilitate the transition of a change in the "multi-bit-binary-outputs", a.k.a. "mbbo", that are controlled by MEDM gain sliders, to the analog electronics on the CM board. Why is this necessary? Imagine changing the gain from 7dB (=0111 in mbbo representation) to 8dB (=1000 in mbbo representation). In order to realize this change, all 4 bits have to change their state. But this almost certainly doesn't happen synchronously, because our EPICS interface isn't synchronous. So at some intermediate times, the mbbo representation could be 0100 (=4dB), or 1111 (=15dB), or many other possible values, which are all significantly different from either the initial value or the desired final state. This is clearly undesirable.

In order to protect against this kind of error, a Latched output part, 74ALS573, is used to buffer the physical digital logic levels from the switches in the analog gain stages. So in the default state, the "LATCH ENABLE" signal line is held "LOW". When a change happens in the EPICS value corresponding to a gain slider, the "LATCH ENABLE" state is quickly toggled to "HIGH", so as to enable the appropriate analog gain stages to be switched, and then again to "LOW", at which point the latch holds its output state. This logic is currently implemented by a piece of code called "latch.o", which is the compiled version of "latch.st", which may be found in /cvs/cds/caltech/target/c1iool0 where it presumably was written for the IMC servo board, but not in /cvs/cds/caltech/target/c1iool0  , which is where the CM board database files reside. The only elog reference I can find pertaining to this particular piece of code is from Alan, and doesn't say anything about the actual logic.

For the new c1iscaux, we need to implement this logic somehow. After discussion between Koji and me, we feel that a piece of python code is sufficient. This would continuously run in the background on the supermicro server machine. The channel hierarchy for each gain channes is as follows (I've taken the example of C1:LSC-CM_REFL1_GAIN):

• C1:LSC-CM_REFL1_GAIN ------ this is the channel tied to an MEDM slider, and so is a "soft" channel
• C1:LSC-CM_REFL1_SET ------- this is a "soft" channel that gets converted to an mbbo
• C1:LSC-CM_REFL1_BITS ------ this is a channel that actually controls (multiple) physical binary outputs on the Acromag

So the logic will be that it continuously scans the EPICS channel C1:LSC-CM_REFL1_GAIN  for a change in set value. When a change is detected, it has to update the C1:LSC-CM_REFL1_SET channel. In the next EPICS refresh cycle, this would result in the mbbo bits, C1:LSC-CM_REFL1_BITS , all changing to the appropriate values. After these changes have happened, we need to toggle the LATCH ENABLE in order to allow the changes to propagate to the analog gain stage switches. Need to think about what's the best way to do this.

14771   Thu Jul 18 10:46:04 2019 gautamUpdateCDSDatabase files made

I completed the translation of the .db files for the EPICS database records from the VME notation to the Acromag/Modbus/Asyn notation. The channels are now organized into 5 database files, located in /cvs/cds/caltech/target/c1iscaux3/,  for convenience:

1. C1_ISC-AUX_LSCPDs.db -------- This handles whitening gain, AA enable/bypass, Demodulator FE, and PD Interface Board channels for REFL11, REFL55, REFL33, REFL165, POP22, POP110, POX11, POY11, AS55 and AS110 photodiodes.
2. C1_ISC-AUX_CM.db -------------- This handles all channels for the CM board. The mbbo addressing notation needs to be checked.
3. C1_ISC-AUX_QPDs.db ----------- This handles all channels for the IPPOS QPD.
4. C1_ISC-AUX_ALS.db ------------- This handles all channels for the IR ALS DFD LO and RF power monitoring.
5. C1_ISC-AUX_SPARE.db ---------- This handles the unused channels for the various whitening, AA and PD interface boards.

For reasons unknown to me, the database files in the other Acromag system target directories (e.g. c1susaux, c1auxex) all had 755 level access permission - maybe this is required for systemctl to handle the EPICS serving? Anyways, I upgraded the permission level of the above 5 files using chmod.

There are almost certainly typos / other errors, and I may have missed copying over some soft/calibrated channels, but I hope that this way of grouping by subsystem will make the debugging less painful. Once Chub connects up the power lines to the Acromags, I will run the soft tests. For this purpose, I've also made a C1_ISC-AUX.cmd file and a C1_ISC-AUX.env file in the above target directory, and also made the modbusIOC.service file in /etc/systemd/system on the supermicro.

14773   Thu Jul 18 19:58:56 2019 gautamUpdateCDSWork on Acromag chassis

Now that the .db files were prepared, I wanted to test for errors. So I did the following:

1. Acromags were mounted on the DIN rails. Attachment #1 shows the grouping of ADC, DAC and BIO units. They are labelled with their IP addresses.
2. Wiring of power:
• Chub had already prepared the backplane with the power connectors, switches and indicator LEDs.
• So I just had to daisy chain the +24 V (RED) and GND (BLACK) terminals for all the acromags together, which I did using 24 AWG wire (we may want to use heavier gauge given the current draw).
3. Ethernet cables were used to daisy chain the network connectivity between the various units.  Attachment #1 shows the current state of the chassis box.
4. Front panel pieces were attached and labelled, see Attachment #2
• I found it was sufficient to use the front - we may use the rear panel slots when we want to add connections for controlling the c1aux machine channels.
• The D15 P2 connector panel for the CM board will arrive tomorrow and will be installed then.
5. Entire setup was connected to power and ethernet, see Attachment #3
• As usual, the current draw is significant for the collection of Acromags, I got around this problem by using the bench supply to "Parallel" mode to enhance the current driving capacity.
• For the ethernet connection, I used the office space port #6, which I connected at the network rack end to the eth1 port of the Supermicro.

All the Acromags are seen on the 192.168.114 subnet on c1iscaux3 - however, when I run the modbusIOC process, I see various errors in the logfile , so more debugging is required. Nevertheless, progress.

Update 2245: Turns out the errors were indeed due to a copy/paste error - I had changed the IP addresses for the ADCs from the .115 subnet c1susaux was using, but forgot to do so for the DACs and BIOs. Now, if I turn off the existing c1iscaux so that there aren't any EPICS clashes, the EPICS server initializes correctly. There are still some errors in the log file - these pertain to (i) the mbbo notation, which I have to figure out, and (ii) the fact that this version of EPICS, 7.0.1, does not support channel descriptions longer than 28 characters (we have several that exceed this threshold). I think the latter isn't a serious problem.

Getting closer... Note that I turned off the c1iscaux VME crate to prevent any EPICS server clashes. I will turn it back on tomorrow.

14776   Fri Jul 19 12:50:10 2019 gautamUpdateSUSDC bias actuation options for SOS

Rana and I talked about some (genius) options for the large range DC bias actuation on the SOS, which do not require us to supply high-voltage to the OSEMs from outside the vacuum.

What we came up with (these are pretty vague ideas at the moment):

1. Some kind of thermal actuation.
2. Some kind of electrical actuation where we supply normal (+/- 10 V) from outside the vacuum, and some mechanism inside the chamber integrates (and hence also low-pass filters) the applied voltage to provide a large DC force without injecting a ton of sensor noise.
3. Use the blue piers as a DC actuator to correct for the pitch imbalance --- Kruthi and Milind are going to do some experiments to investigate this possibility later today.

For the thermal option, I remembered that (exactly a year ago to the day!) when we were doing cavity mode scans, once the heaters were turned on, I needed to apply significant correction to the DC bias voltage to bring the cavity alignment back to normal. The mechanism of this wasn't exactly clear to me - furthermore, we don't have a FLIRcam picture of where the heater radiation patter was centered prior to my re-centering of it on the optic earlier this year, so we don't know what exactly we were heating. Nevertheless, I decided to look at the trend data from that night's work - see Attachment #1. This is a minute trend of some ETMY channels from 0000 UTC on 18 July 2018, for 24 hours. Some remarks:

1. We did multiple trials that night, both with the elliptical reflector and the cylindrical setup that Annalisa and Terra implemented. I think the most relevant part of this data is starting at 1500 UTC (i.e. ~8am PDT, which is around when we closed shop and went home). So that's when the heaters were turned off, and the subsequent drift of PIT/YAW are, I claim, due to whatever thermal transients were at play.
2. Just prior to that time, we were running the heater at close to its maximum rated current - so this relaxation is indicative of the range we can get out of this method of actuation.
3. I had wrongly claimed in my discussion with Rana this morning that the change in alignment was mostly in pitch - in fact, the data suggests the change is almost equal in the two DoFs. Oplev and OSEMs report different changes though, by almost a factor of 2....
4. The timescale of the relaxation is ~20 minutes - what part(s) of the suspension take this timescale to heat up/cool down? Unlikely to be the wire/any metal parts because the thermal conductivity is high?
5. In the optimistic scenario, let's say we get 100 urad of actuation range - over 40m, this corresponds to a beam spot motion of ~8mm, which isn't a whole lot. Since the mechanism of what is causing this misalignment is unclear, we may end up with significantly less actuation range as well.
6. I will repeat the test (i.e. drive the heater and look for drift in the suspension alignment using OSEMs/Oplev) in the afternoon - now I claim the radation pattern is better centered on the optic so maybe we will have a better understanding of what mechanisms are at play.

Also see this elog by Terra.

Attachment #2 shows the results from today's heating. I did 4 steps, which are obvious in the data - I=0.6A, I=0.76A, I=0.9A, and I=1.05A.

In science, one usually tries to implement some kind of interpretation. so as to translate the natural world into meaning.

14777   Fri Jul 19 15:51:55 2019 gautamUpdateGeneralProjector lightbulb blown out

[chub, gautam]

Bulb replaced. Projector is back on.

14778   Fri Jul 19 15:54:47 2019 gautamUpdateGeneralControl room UPS Batteries need replacement

The control room UPS started making a beeping noise saying batteries need replacement. I hit the "Test" button and the beeping went away. According to the label on it, the batteries were last repalced in March 2016, so maybe it is time for a replacement, @Chub, please look into this.

14780   Fri Jul 19 17:42:58 2019 gautamUpdateGeneralrossa Xdisp bricked

For some reason, rossa's Xdisplay won't start up anymore. This happened right after the UPS reset. Koji and I tried ~1.5 hours of debugging, got nowhere.

14781   Fri Jul 19 19:44:03 2019 gautamUpdateCDSDatabase file test

Summary:

The database files for C1ISCAUX seem to work file - the exception being the mbbo channels for the CM board.

Details:

This was just a software test - the actual functionality of the channels will have to be tested once the Acromag crate has been installed in the rack. One change I had to make on the MEDM screen for the LSC PD whitening gains was to get rid of the "NMS" suffix on the EPICS channel names for whitening gain sliders/drop-down-menus. I suspect this has to do with the EPICS version we are using, 7.0.1. Furthermore, AS165 and POP55 no longer exist - I hold off removing them from the MEDM screen for the moment.

Next steps:

From the software point of view, the major steps are:

1. Fix the mbbo channel notation in the database files
2. Write and test the latch enabling code
3. Figure out what scripted tests can be done to test the functionality of the new Acromag box.

I am stopping the EPICS server on the new machine and restarting the old VME crate over the weekend.

14783   Sat Jul 20 01:03:37 2019 gautamUpdate Dataviewer error

What channels are you trying to read?

 Quote: I'm not able to get trends of the TM adjustment test that Rana had asked us to perform, from the dataviewer. It's throwing the following error: Connecting to NDS Server fb (TCP port 8088) Connecting.... done Server error 7: connect() failed datasrv: DataWrite failed: daq_send: Resource temporarily unavailable T0=19-07-20-01-27-39; Length=600 (s) No data output.
14784   Sat Jul 20 11:24:04 2019 gautamUpdateGeneralrossa bricked

Summary:

SnapPy scripts made to work on Pianosa.

Details:

Of course rossa was the only machine in the lab that could run the python scripts to interface with the GigE camera. And it is totally bricked now. Lame.

So I installed several packages. The key was to install pypylon - if you go to the basler webpage, pypylon1.4.0 does not offer python2.7 support for x86_64 architecture, so I installed pypylon1.3.0. Here are the relevant lines from the changelog:

gstreamer-plugins-bad-0.10.23-5.el7.x86_64    Sat 20 Jul 2019 11:22:21 AM PDT gstreamer-plugins-good-0.10.31-13.el7.x86_64  Sat 20 Jul 2019 11:22:11 AM PDT gstreamer-plugins-ugly-0.10.19-31.el7.x86_64  Sat 20 Jul 2019 11:20:08 AM PDT gstreamer-python-devel-0.10.22-6.el7.x86_64   Sat 20 Jul 2019 10:34:35 AM PDT pygtk2-devel-2.24.0-9.el7.x86_64              Sat 20 Jul 2019 10:34:34 AM PDT pygobject2-devel-2.28.6-11.el7.x86_64         Sat 20 Jul 2019 10:34:33 AM PDT pygobject2-codegen-2.28.6-11.el7.x86_64       Sat 20 Jul 2019 10:34:33 AM PDT gstreamer-devel-0.10.36-7.el7.x86_64          Sat 20 Jul 2019 10:34:32 AM PDT gstreamer-python-0.10.22-6.el7.x86_64         Sat 20 Jul 2019 10:34:31 AM PDT gtk2-devel-2.24.31-1.el7.x86_64               Sat 20 Jul 2019 10:34:30 AM PDT libXrandr-devel-1.5.1-2.el7.x86_64            Sat 20 Jul 2019 10:34:28 AM PDT pango-devel-1.42.4-1.el7.x86_64               Sat 20 Jul 2019 10:34:27 AM PDT harfbuzz-devel-1.7.5-2.el7.x86_64             Sat 20 Jul 2019 10:34:26 AM PDT graphite2-devel-1.3.10-1.el7_3.x86_64         Sat 20 Jul 2019 10:34:26 AM PDT pycairo-devel-1.8.10-8.el7.x86_64             Sat 20 Jul 2019 10:34:25 AM PDT cairo-devel-1.15.12-3.el7.x86_64              Sat 20 Jul 2019 10:34:25 AM PDT mesa-libEGL-devel-18.0.5-3.el7.x86_64         Sat 20 Jul 2019 10:34:24 AM PDT libXi-devel-1.7.9-1.el7.x86_64                Sat 20 Jul 2019 10:34:24 AM PDT pygtk2-doc-2.24.0-9.el7.noarch                Sat 20 Jul 2019 10:34:23 AM PDT atk-devel-2.28.1-1.el7.x86_64                 Sat 20 Jul 2019 10:34:21 AM PDT libXcursor-devel-1.1.15-1.el7.x86_64          Sat 20 Jul 2019 10:34:20 AM PDT fribidi-devel-1.0.2-1.el7.x86_64              Sat 20 Jul 2019 10:34:20 AM PDT pixman-devel-0.34.0-1.el7.x86_64              Sat 20 Jul 2019 10:34:19 AM PDT libXinerama-devel-1.1.3-2.1.el7.x86_64        Sat 20 Jul 2019 10:34:19 AM PDT libXcomposite-devel-0.4.4-4.1.el7.x86_64      Sat 20 Jul 2019 10:34:19 AM PDT libicu-devel-50.1.2-15.el7.x86_64             Sat 20 Jul 2019 10:34:18 AM PDT gdk-pixbuf2-devel-2.36.12-3.el7.x86_64        Sat 20 Jul 2019 10:34:17 AM PDT pygobject2-doc-2.28.6-11.el7.x86_64           Sat 20 Jul 2019 10:34:16 AM PDT pygtk2-codegen-2.24.0-9.el7.x86_64            Sat 20 Jul 2019 10:34:15 AM PDT

Camera server is running on a tmux session on pianosa. But it keeps throwing up some gstreamer warnings/errors, and periodically (~every 20 mins) crashes. Kruthi tells me that this behavior was seen on Rossa as well, so whatever the problem is, doesn't seem to be because I missed out on installing some packages on pianosa. Moreover, if the server is in fact running, I am able to take a snapshot - but the camera client does not run.

14785   Sat Jul 20 11:57:39 2019 gautamSummaryCDSP2 interface board

The boards arrived. I soldered on a DIN96 connector, and tested that the goemetry will work. It does . The only constraint is that the P2 interface board has to be installed before the P1 interface is installed. Next step is to confirm that the pin-mapping is correct. The pin mapping from the DIN96 connector to the DB15 was also verified.

*Maybe it isn't obvious from the picture, but there shouldn't be any space constraint even with the DB37/DB15 cables connected to the respective adapter boards.

14786   Sat Jul 20 12:16:39 2019 gautamUpdateCamerasCNNs for beam tracking || Analysis of results
1. Make the MSE a subplot on the same axes as the time series for easier interpretation.
2. Describe the training dataset - what is the pk-to-pk amplitude of the beam spot motion you are using for training in physical units? What was the frequency of the dither applied? Is this using a zoomed-in view of the spot or a zoomed out one with the OSEMs in it? If the excursion is large, and you are moving the spot by dithering MC2, the WFS servos may not have time to adjust the cavity alignment to the nominal maximum value.
3. What is the minimum detectable motion given the CCD resolution?
4. Please upload a cartoon of the network architecture for easier visualization. What is the algorithm we are using? Is the approach the same as using the bright point scatterers to signal the beam spot motion that Gabriele demonstrated successfully?
5. What is the significance of Attachment #6? I think the x-axis of that plot should also be log-scaled.
6. Is the performance of the network still good if you feed it a time-shuffled test dataset? i.e. you have (pictures,Xcoord,Ycoord) tuples, which don't necessarily have to be given to the network in a time-ordered sequence in order to predict the beam spot position (unless the network is somehow using the past beam position to predict the new beam position).
7. Is the time-sync problem Koji raised limiting this approach?
14789   Sun Jul 21 12:54:18 2019 gautamUpdateLoss MeasurementMC2 loss map

Can you please be more specific about what the error is? Is this the usual instability with the camera server code? Or was it something new?

 Quote: The camera server is throwing an error and is not grabbing snapshots :(
14790   Sun Jul 21 12:55:38 2019 gautamUpdateCDSCM board Latch Enable test script

DATED, SEE ELOG14941 for the most up-to-date info on latch.py.

I wrote (/cvs/cds/caltech/target/c1iscaux3/latch.py) and tested the logic illustrated in Attachment #1. Results of a test are shown in Attachment #2, the various channels change as expected. Note that for negative values of the gain channel, the corresponding "BITS" channel will take on values like 65536 - this is because the mbboDirect data type is a 16 bit data type, and presumably the MSB is the sign bit. A bit mask is applied to this channel before the actual BIO unit bits are set - we should verify that the correct behavior happens, but I don't immediately see any problems.

To me, this is a robust logic, but it will benefit from more sets of eyes giving it a look over. The idea is to run this continuously on the Supermicro machine.

Apart from this, I also fixed some errors in the mbboDirect record syntax - so now I am able to start up the EPICS server without it throwing any error messages. It remains to verify that changing an EPICS gain slider results in the appropriate gain bits being flipped in the correct way (on the hardware side, I think the correct behavior is happening on the software end). For this testing, I turned off the old c1iscaux crate at ~10am, and started up the server on c1iscaux3. I am reverting to the nominal config now (~1pm).

Further testing will require the wiring inside the Acromag chassis to be completed. This should be the priority task for next week.

*Update 1130 22 July 2019: I've now installed the required dependencies on c1iscaux3 and setup the latch.py script to run as a systemctl process dependent on modbusIOC.service.

14795   Mon Jul 22 07:21:13 2019 gautamUpdateCDSpainosa messed with

Somebody changed the settings on painosa without elogging anything about it. Why does this keep happening? I thought the point of the elog was to communicate. I think there are sufficient number of problems in the lab without me having to manually reset the control room workstation settings every week. Please make an elog if you change something.

14800   Mon Jul 22 23:53:16 2019 gautamUpdateALSIR ALS locking attempt

Summary:

My goal tonight was to lock the PSL frequency to be resonant in the XARM cavity, using the PSL+EX beat as the error signal. I was not successful - mainly, I was plagued by huge BR mode coupling in the error signal, and I could not enable the BR notch filter in the control loop without breaking the lock. Need to think about next steps.

Details:

• POX and POY locking was easily restored.
• EX green alignment was tweaked at the end-table. A large YAW correction was required, which I opted to apply on the mechanical mirror mounts rather than the PZTs. GTRX ~0.4 was recovered.
• The arm cavity length was first locked using POX as an error signal
• Then I looked at the out-of-loop ALS noise, trusting the DFD's V/Hz calibration (red-trace in Attachment #1).
• I judged it to be close enough to the benchmark reference (green-trace in Attachment #1), and so decided that I could go ahead and try locking.
• A modified version of the script /opt/rtcds/caltech/c1/scripts/XARM/Lock_ALS_XARM.py was used to transition control from POX to the ALS error signal
• I found that I had to change the sign of the CARM loop gain for the servo to remain stable (in this config, CARM-->MC2 length, thereby modifying the IMC frequency to keep the PSL resonant in the XARM cavity).
• I don't know why this sign change was required - we are still sticking to the same convention that the beat frequency increases when the temperature slider for the EX laser is incremented in counts.
• The script failed multiple times at the BOOST/BR notch filter enabling step.
• Doing these steps manually, I found that turning the BR notch, FM6, ON destroyed the lock immediately.
• Motivated by this observation, I looked at the in-loop error signal spectrum, see Attachment #2. Here, the PSL frequency is servoed by the ALS error signal, but the BR notch filter isn't enabled.
• The Bounce-mode peak is huge - where is this coming from? It is absent in the ALS spectrum when the XARM is locked with POX. So it is somehow connected with actuating on the MC2 suspension? Or is it that the FM6=BounceRoll filter of the XARM loop is squishing the noise when looking at the ALS spectrum in POX lock, i.e. Attachment #1? In which case, why can't I engage FM6 for the CARM loop???

Anyway, now that I have a workable set of settings that gets me close to the ALS lock of the XARM, I expect debugging to proceed faster.

Update 2019 July 23: I looked at the control loop shape today, see Attachment #3. I'm not sure I understand why the "BounceRoll" filter  in this filter bank looks like a resonant gain rather than a notch, as it does for the Oplev or SUSPOS loops for example - don't we want to not actuate at these frequencies because the reason the signal exists is because of the imperfect OSEM/magnet positioning? This does not explain the spectrum shown in Attachment #2 however, as that filter was disabled.

14802   Wed Jul 24 00:22:24 2019 gautamUpdateALSPSL frequency locked to XARM length using ALS

Summary:

I succeeded in locking the PSL frequency to the XARM cavity length, with 9 pm RMS (Attachment #1) motion below 1 kHz, by actuating on MC2 to change the IMC length. The locks were pretty stable (~20 minutes) - the dominant cause of lockloss was the infamous ETMX drifting problem.

Details:

1. I did not need to do anything to fix the anomalosly high BR mode coupling I reported yesterday .
• To test where this could be coming from - I looked at the ALS spectrum again with the XARM length locked to the PSL frequency using POX.
• Then I compared the spectra with the BR filter in the XARM servo enabled/disabled, see Attachment #2
• There bounce/roll peak heights even with the BR filter disabled is ~x100 smaller than what I reported yesterday (it remained the case today, because without enabling the BR filter in the CARM servo bank, the TRX level was fluctuating wildly at ~16 Hz).
2. The CARM loop (which is what the PSL frequency was slaved to) had ~150 Hz UGF with ~40 degrees phase margin, see Attachment #3.
3. The quoted RMS sensing noise is if we trust the old POX calibration - may be off by a factor of a few, but probably not an order of magnitude. I'll recalibrate using the free-swinging Michelson technique in the coming days.
4. The two broad humps in Attachment #1, centered at ~180 Hz and ~300 Hz, are present in the XARM lock as well - so it is somehow imprinted on the arm cavity length. Fixing that will improve the RMS noise performance significantly.

My main motivation here is to make some measurements and investigate the SoCal idea using a toy system, i.e. a single arm cavity controlled using ALS, so that's what Craig and I will attempt next.

14808   Wed Jul 24 20:23:52 2019 gautamUpdateCamerasUpgraded Pylon from 5.0.12 to 5.2.0

Since there are multiple SURF projects that rely on the cameras:

1. I moved the new installs Jon made to "new_pylon5" and "new_pypylon". The old installs were moved back to be the default directories.
2. The bashrc alias for pylon was updated to allow the recording of videos (i.e. it calls the PylonViewerApp from new_pypylon).
3. There is a script that can grab images at multiple exposures and save 12-bit data as uint16 numpy arrays to an HDF5 file. Right now, it is located at /users/kruthi/scripts/grabHDR.py. We can move this to a better place later, and also improve the script for auto adjusting the exposure time to avoid saturations.

My changes were necessary because the grabHDR.py script was throwing python exceptions, whereas it was running just fine before Jon's changes. We can move the "new_*" dirs to the default once the SURFs are gone.

Let's freeze the camera software config in this state until next week.

14811   Thu Jul 25 12:25:56 2019 gautamUpdateALSIR ALSX noise

Summary:

1. There are some broad peaks in the ALS out-of-loop noise, centered at ~145 Hz, ~245 Hz and ~570 Hz which are absent in both the POX in-lock error signal and in the green PDH error signals (see Attachment #1). So I conclude they originate in the IR ALS beat chain somewhere. Needs more investigation, in the general quest to improve the ALS noise.
2. This measurement also shows that the ALS noise is limited by unsuppressed EX green PDH frequency noise above ~400 Hz (100 Hz if you ignore the unexplained broad humps).

These spectra were taken with the arm cavity length locked to the PSL frequency using POX as an error signal, and the EX laser frequency locked to the XARM cavity length by the analog PDH servo at EX, so there is no feedback control with the ALS beat signal as an error signal.

Other details:

• The transition of arm resonance control from POX to ALS error signal is more robust now - I am able to do this during daytime, and also maintain the lock for >20 minutes at a time.
• Rana encouraged me not to spend too much time on this - so my next goal here will be to get the Y arm IR ALS working, and then we can control the two arms using ALS error signals in the CARM/DARM basis instead of the X/Y basis.
• I still think it's worth getting the ALS good enough that the locking becomes repeatable and reliable.
• The main task here is going to be re-doing the EY green layout to match the EX layout, get good MM into the cavity etc.
• The IR light also has to be coupled into the fiber at EY.
14812   Thu Jul 25 14:28:03 2019 gautamConfigurationComputersfirewalld disabled for EPICS CA

I think rana did some more changes to this workstation to make it useful for commissioning activities - but the MEDM screens were still white blanks. The problem was that the firewalld wasn't disabled (last two steps of the KThorne setup wiki). I disabled it. Now donatella can run MEDM, ndscope and StripTool. DTT doesn't work to get online data because of a "Synchronization Error", I'm not bothering with this for now. I think Kruthi successfully demonstrated the fetching of offline data with DTT.

ELOG V3.1.3-