 Wed Mar 7 12:04:14 2018, gautam, Update, Electronics, Three opamps walked onto an AA board 
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Here are the plots. Comments:
Measurement and model agree quite well .
Of the 3 OpAmps, the ones installed seem |
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Thu Mar 8 00:40:25 2018, gautam, Update, ALS, new look ALS electronics - characterization
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I am almost ready for a digital test of the new ALS electronics. Today, Koji and I spent some time tapping new +/-24VDC DIN terminal blocks at the LSC
rack to facilitate the installation of the 1U differential receiving AA chassis (separate elog entry). The missing piece of the puzzle now is the timing
adapter card. I opted against trying a test tonight as I am having some trouble bringing c1lsc back online. |
 Thu Mar 8 01:10:22 2018, gautam, Update, General, CDS recovery after work at LSC rack
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This required multiple hard reboots, but seems like all the RT models are back for now. The only indicator I can't explain is the red DC field on
c1oaf. Also, the SUS model seems to be overclocking more frequently than usual, though I can't be sure. The "timing" field of this model's
state word is RED, while the other models all seem fine. Not sure what could be going on. |
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Thu Mar 8 14:41:25 2018, gautam, Update, General, CDS recovery after work at LSC rack
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As I had found before, restarting the c1oaf model fixed the DC error. There is however still a pesky red indicator light on the "ADC0"
in c1oaf. Trying to open up the ADC |
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Thu Mar 8 15:23:16 2018, gautam, Update, Electronics, New DC power ports at c1lsc
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[Koji, Gautam]
Yesterday, we installed some new DIN rail connectors at the LSC rack to provide 3 new outputs each for +24V DC and -24V DC. The main motivation
was to facilitate the installation and powering of the differential receiving AA board. The regulators used inside the 1U chassis actually claims a dropout |
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Thu Mar 8 18:15:42 2018, gautam, Update, General, CDS recovery after work at LSC rack
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I was forced into a simultaneous power-cycle rebooting of the three vertex FEs just now. I took the opportunity to completely disconnect the c1sus expansion
chassis from all power and then restart it.
Everything is back up right now, and the weird timing issues I noticed in the sus model seem to be gone now (I'll need a longer baseline |
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Thu Mar 8 19:38:37 2018, gautam, Update, ALS, digital unwhitening of daughter board
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I made a LISO fit of the measured TF of the daughter board, so that I can digitally invert the daughter board whitening. Results attached. (Inverse)
Filters have been uploaded to the ALS X Foton filter banks. |
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Thu Mar 8 23:50:27 2018, gautam, Update, ALS, First look at new ALS electronics
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Locked single arms, dither aligned, and saved offsets to EPICS (slow) sliders in anticipation of having to reboot all vertex FEs.
Shutdown
ETMY watchdog, stopped all models on c1iscey, and shutdown that frontend.
Walked down to Y-end, powered of c1iscey expansion chassis, and removed
the ADC adaptor card.
Stopped all models on c1lsc. Shutdown watchdog on all optics in anticipation of c1sus model failing. Shutdown the c1lsc |
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Fri Mar 9 01:07:01 2018, gautam, Update, ALS, First look at new ALS electronics
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[koji, gautam]
I was going to head out but then it occurred to me that I could do another simple test, which is to try and lock the X arm on ALS error signal
(i.e. actuate on MC length to keep the beat between EX laser and PSL fixed, while the EX frequency is following the Xarm length). Comparing the in loop |
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Fri Mar 9 12:59:53 2018, Kira, Update, PEM, ADC noise measurement
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[Kira, Gautam]
I ceated a simple circuit that takes in 15V and outputs precisely 5V by using a 12V voltage regulator LM7812 and an AD586 that takes the output
of the voltage regulator and outputs 5V (attachment 1). We plugged this into the slow channel and will leave it running for a few hours to see if we still |
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Mon Mar 12 13:58:37 2018, gautam, Update, General, projector light bulb blown
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Bulb went out ~10am today. Looks like the lifetime of this bulb was <100 days.
Steve: bulb is arriving next week
Quote:
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Mon Mar 12 22:08:31 2018, gautam, Update, ALS, Noisy POX
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[kevin, gautam]
we tested my noisy POX hypothesis tonight. By locking the single arm with POX, the arm length is forced to follow PSL frequency, which is itself
slaved to IMC length. From Attachment #1, there is no coherence between the arm control signal and MC_F. This suggests to me that the excess noise I am |
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Mon Mar 12 23:57:31 2018, gautam, Update, ALS, Noisy POX
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[kevin, gautam]
Kevin suggested I shouldn't be so lazy and test the POY spectrum as well. So we moved the timing card back to c1iscey, went through the usual
dance of vertex machine reboots, and then got both single arm locks going. Attached spectrum shows that both POX and POY are noisy. I'm not sure what |
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Thu Mar 15 17:33:56 2018, Kira, Update, PEM, test setup
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I have attached the setup I completed today. The metal box contains the heater circuit and the board for the temperature sensor is right above it.
This is basically the same setup as before, but I've just packaged everything up neater. I expect to be able to perform the test tomorrow and begin
implementing PID control. I still need a DAC input for the heater circuit and the temperature sensor is having some issues as well. |
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Fri Mar 16 09:36:56 2018, Steve, Update, VAC, RGA scan at day 511,218d
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Pumpdown 80 at 511 days and pd80b at 218 days
Valve configuration: special vacuum normal, annuloses are not pumped at 3 Torr, IFO pressure 7.4e-6 Torr at vac envelope temp 22 +- 1C
degrees |
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Mon Mar 19 15:02:29 2018, gautam, Update, ALS, Noisy MC sensing
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The working hypothesis, since the excess noise in single arm locks is coherent between both arms, the excess sensing noise is frequency noise in the
IMC locking loop (sensing because it doesn't show up in MC_F). I've started investigating the IMC sensing chain, starting with the power levels
of the RF modulation source. Recall that we had changed the way the 29.5MHz signal was sent to the EOM and demod electronics in |
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Mon Mar 19 23:44:00 2018, gautam, Update, IOO, IMC loop checkup
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[koji, gautam]
I began my investigations by measuring the voltage noise of the demod board outputs with an SR560 (G=100) and SR785 in the audio band.
Measurement
made with PSL shutter closed, LO input of demod board driven with the nominal level of ~2.5dBm, RF input terminated.
Motivation was to look |
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Tue Mar 20 16:53:03 2018, gautam, Update, IOO, IMC loop checkup
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Re-measured the demod board noises after replacing the suspect ERA-5SMs, with LO driven by a marconi at the "nominal" level of 2.5dBm, and
RF input terminated. Attachment #1 is the input referred voltage noise spectra. I used the FET low noise pre-amp box for this purpose. I cannot explain
the shape of the spectra above 1kHz. I tried doing the measurement on a minicircuits mixer (non-surface mount) and found |
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Tue Mar 20 16:56:01 2018, Kira, Update, PEM, test setup
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The MOSFET was getting pretty hot, so I switched it out to a larger heat sink and it's fine now. I then used a function generator in place of the
DAC to provide ~3.5V. I got the current in the circuit to 1.7A, which is as expected, since we have 24V input, the heater resistance is 12.5ohm and the
resistor we are using is 1ohm, so 24V/(12.5+1)ohm = 1.7A. The temperature inside the can rose about 5 degrees in half an hour. The only issue now |
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Tue Mar 20 19:48:10 2018, gautam, Update, PEM, test setup
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according to the temp sensor readout, which was ~-3.35V which corresponds to ~335K, the temperature of the can is now 60
deg C. This is a bit warm for my liking so i'm turning the heater current down to 0 now by writing 0 to C1:PEM-SEIS_EX_TEMP_CTRL |
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Tue Mar 20 21:08:03 2018, gautam, Update, IOO, IMC loop checkup
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This elog by koji inspired me to consider power supply as a possible issue.
The demod board receives +/-24V DC (which is regulated down to +/-15V DC by 7815/7915), and also +15V DC via the backplane. The ERA-5SM receives
DC power from the latter (unregulated) +15V DC. I can't think of why this is the case except perhaps the |
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Tue Mar 20 22:44:45 2018, gautam, Update, IOO, IMC loop checkup
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After some persistence, I managed to get the mixers off.
Having gotten the mxiers off, I decided to temporarily solder on 50ohms between the LO pin pad and ground on the demod board and measure
the RF signal levels in the LO chain with the active probe again.
Today, with this change, I confirmed that the ERA-5SM begins to saturate closer |
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Wed Mar 21 10:00:35 2018, steve, Update, General, projector light bulb replaced
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Light bulb replaced.
Quote:
Bulb went out ~10am today. Looks like the lifetime of this bulb was <100 days. |
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Wed Mar 21 15:52:45 2018, gautam, Update, IOO, MC error point calibration
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As discussed at the meeting, I decided to calibrate the MC error point into physical units of Hz/rtHz (a.k.a. the PDH discriminant). This is to facilitate the debugging of the hypothesized
excess IMC sensing noise. I did this as follows. |
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Wed Mar 21 17:31:21 2018, gautam, Update, IOO, MC error point calibration
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I did a preliminary noise budget of the transmitted frequency noise of the IMC. Attachment #1 shows the NB. I'm going to use this opportunity to
revisit my IMC modeling. Some notes:
The blue, green and red traces |
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Wed Mar 21 21:13:44 2018, gautam, Update, IOO, IMC noise budget
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I've added two curves to the NB. Both are measured (with FET preamp) at the output of the demod board, with the LO driven at the nominal level by
the Wenzel RF source pickoff (as it would be when the IMC is locked) and the RF input connected to the IMC REFL PD. For one curve, I simply closed the
PSL shutter, while for the other, I left the PSL shutter open, but macroscopically misaligned MC2 so that there was no IMC cavity. So barring RFAM, there |
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Fri Mar 23 12:00:20 2018, rana, Update, PEM, test setup
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we don't ever want to use our 16 kHz real time system for such low frequency action; its main purpose is for real-time controls, whereas we are OK
with multiple seconds of delay in a thermal loop. The Python PID script is sufficient and highly reliable (after years of testing). |
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Fri Mar 23 12:45:08 2018, Kira, Update, PEM, test setup
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I fit the data that we got from the test. The time constant for the cooling came out to be about 4.5 hours. The error is quite large and we should add
a low pass filter to the temperature sensor eventually in order to minimize the noise of the measurements. |
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Mon Mar 26 09:25:18 2018, Steve, Update, VAC, VM1 opened
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CC1 old MKS cold cathode gauge randomly turns on- off. This makes software interlock close VM1 to protect RGA So the closed off RGA region
pressure goes up and the result is distorted RGA scan.
CC1 MKS gauge is disconnected and VM1 opened. This reminds me that we should connect our interlocks to CC1 Hornet |
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Mon Mar 26 10:15:20 2018, Arijit, Update, IOO, PMC and IMC re-locked
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[Gautam, Arijit]
PMC and IMC re-aligned and re-locked. Both cavities are staying locked. Arm cavities are also locked. |
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Mon Mar 26 16:10:33 2018, Kira, Update, PEM, final setup sketch
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I made sketches of the final setup. There will be a box in the rack that contains both the heater circuit and the temperature sensor boards. One of them
is in the loop while the other isn't. Instead of having many cables leading to the can, there will only be these three, though they can be made into
a single wire. It will be connected to the can through a D-9 connector. The second attachment is what will be inside of the box, with all the major wires |
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Mon Mar 26 23:49:27 2018, gautam, Update, General, New ADC Adaptor Board installed in C1LSC expansion chassis
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Todd informed me that the ADC Timing adaptor boards we had ordered arrived today. I had to solder on the components and connectors as per the schematic,
though the main labor was in soldering the high density connectors. I then proceeded to shut down all models on c1lsc (and then the FE itself). Then classic
problem of all vertex machines crashing when unloading models on c1lsc happened (actually Koji noticed that this was happening even on c1ioo). Anyways |
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Tue Mar 27 01:39:44 2018, gautam, Update, IOO, PSL noise eater was off
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While Kevin and Arijit were doing their MC_REFL PD noise measurements (which they will elog about separately shortly), I noticed a feature around 600kHz
that reminded me of the NPRO noise eater feature. This is supposed to suppress the relaxation oscillation induced peak in the RIN of the PSL. Surprisingly,
the noise eater switch |
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Tue Mar 27 08:58:21 2018, Steve, Update, VAC, VM1 opened.......scan fine
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Quote:
CC1 old MKS cold cathode gauge randomly turns on- off. This makes software interlock close VM1 to protect |
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Tue Mar 27 11:11:16 2018, Kira, Update, PEM, Channel setup
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[Kira, Gautam]
We setup the channels for PID control of the seismometer can. First, we ssh into c1auxex and went to /cvs/cds/caltech/target/c1auxex2 and found
ETMXaux.db. We then added in new soft channels that we named C1:PEM-SEIS_EX_TEMP_SLOWKP, C1:PEM-SEIS_EX_TEMP_SLOWKI, C1:PEM-SEIS_EX_TEMP_SLOWKD |
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Tue Mar 27 19:32:03 2018, arijit, Update, IOO, PSL noise eater was off
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Kevin, Gautam and Arijit
We made a measurement of the MC_REFL photodiode transfer function using the network analyzer. We did it for two different power input (0dB and
-10dB) to the test measurement point of the MC_REFL photodiode. This was important to ensure the measurements of the transfer function of the MC_REFL photodiode |
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Tue Mar 27 23:37:35 2018, gautam, Update, IOO, MC REFL PD removed
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I've removed the MC REFL PD unit
from the AS table for investigation. So MC won't lock.
PSL shutter was closed and location of PD was marked with sharpie (placing guides to indicate position wasn't convenient). I also kapton |
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Wed Mar 28 16:44:27 2018, Steve, Update, General, AP table today
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MCRefl is absent, it is under investigation. I removed a bunch of hardware and note all spare optics along the edges.
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Wed Mar 28 17:28:58 2018, Steve, Update, PSL, noise eater on or off
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Till RIN measurement noise eater is off on 2W laser. The inno 1W has no noise eater.
2010 power v current table is below.
Quote:
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Wed Mar 28 21:31:39 2018, gautam, Update, IOO, MC REFL PD removed
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I re-installed the MC REFL photodiode. Centered beam on the PD by adjusting steering mirror to maximize the DC signal level (on o'scope) at the DC
monitoring port. Curiously, the DC level on the scope (high-Z) was ~2.66V DC, whereas the MEDM screen reports ~twice that value, at ~5.44 "V".
We may want to fix this "calibration" (or better yet, use physical units like mW). Noise-eater On/Off comparison of MC error signals to follow. |
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Wed Mar 28 21:47:37 2018, arijit, Update, IOO, MCREFL_PD Optical response measurement
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Kevin, Gautam and Arijit
We did a optical measurement of the MCREFL_PD transimpedance using the Jenny Laser set-up. We used 0.56mW @1064nm on the NewFocus 1611 Photodiode
as reference and 0.475mW @1064nm on the MCREFL_PD. Transfer function was measured using the AG4395 network analyzer. We also fit the data using the refined |
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Thu Mar 29 17:14:42 2018, Kira, Update, PEM, PID test
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[Kira, Gautam]
We closed the loop today and implemented the PID script. I have attached the StripTool graph for an integral value of 0.5 and proportional value
of 20. We had some issues getting it to work properly and it would oscillate between some low values of the control voltage. The set point here was -3.20, |
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Thu Mar 29 17:57:36 2018, arijit, Update, IOO, MCREFL_PD Optical response measurement
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Kevin, Gautam and Arijit
Today we performed the in-loop noise measurements of the MCREFL-PD using the SR785 to ascertain the effect of the Noise Eater on the laser. We
took the measurements at the demodulated output channel from the MCREFL-PD. We performed a series of 6 measurements with the Noise Eater ''ON'' |
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Fri Mar 30 03:23:50 2018, Koji, Update, General, aLIGO EOM work
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I have been working on the aux beat setup on the PSL table between 9PM-3AM.
This work involved:
- Turning off the main marconi |
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Fri Mar 30 06:14:31 2018, rana, Update, IOO, MCREFL_PD Optical response measurement
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| the noise eater on/off measurements should be done for 0-100 kHz and from the demod board output monitor |
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Fri Mar 30 06:16:45 2018, rana, Update, PEM, PID test
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Can't really figure out what this plot means. We need to see the sensor (in units of deg C) and the control signal (in heating power (W)). The plot
should show a few step responses with the PID loop on, so that we can see the loop response time. Please zoom in on the axes so that we can see what's
happening. |
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Fri Mar 30 16:10:46 2018, Kira, Update, PEM, PID test
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I created two new channels today, C1:PEM-SEIS_EX_TEMP_MON_CELCIUS, which turns the output voltage signal into degrees C, and C1:PEM-SEIS_EX_TEMP_CTRL_WATTS,
which takes the input voltage from the DAC and turns it into a value of watts. I'm trying to stabilize the temperature at 35 degrees, but it's
taking a lot longer than expected. Perhaps we'll need to use different values for P and I and decrease the noise in the sensor, since right now there's |
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Fri Mar 30 22:37:36 2018, Kevin, Update, IOO, MCREFL_PD Optical response measurement
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[Gautam, Kevin]
We redid the measurement measuring the voltage noise from the REFL PD demod board output monitor with an SR785 with the noise eater on and off.
We used a 100x preamp to amplify the signal above the SR785 noise. The SR785 noise floor was measured with the input to the preamp terminated with 50 ohms. |
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Mon Apr 2 15:14:21 2018, Koji, Update, General, Modulation depth measurement for an aLIGO EOM
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The new matching circuit was tested.
Results: |
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Wed Apr 4 16:23:10 2018, Kira, Update, PEM, PID test
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I did a step response for the loop from 35 degrees to 40 degrees. The PID is not properly tuned, so the signal oscillates. In the graph, the blue curve
is the temperature of the can in celcius and the green curve is the heating power in watts. The x-axis is in minutes. Before, the signal was too noisy
to do a proper step response, so I placed a 3.3 microF capacitor in parallel with the resistor in my temperature sensor circuit (I'll draw and attach |