40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
 40m Log, Page 300 of 344 Not logged in
ID Date Author Type Category Subject
7248   Wed Aug 22 11:41:20 2012 steveUpdateGeneralgrout plate for optical table at the ends

Reinforced concrete grout plate for existing carbon steel stands at the ends.

Attachment 1: IMG_1561.JPG
Attachment 2: 08231201.PDF
3448   Fri Aug 20 15:49:14 2010 steveUpdatePEMgrouting is done

The preparation for pouring concrete is continuing. The grout forms were removed. Half inch ribbed steel bars were epoxied into our 4" thick floor.

The concrete holding sides- forms are cut to size. They will be installed on Monday morning and pouring concrete should follow.

We can be planning for cleaning up on Tuesday

Atm1, epoxy used bars

Atm2, south west tripod feet grouted

Atm3, ribbed bars are getting ready

Attachment 1: P1060699.JPG
Attachment 2: P1060700.JPG
Attachment 3: P1060704.JPG
3444   Thu Aug 19 16:03:59 2010 steveUpdatePEMgrouting of PSL tripod legs

The 10' x 6' optical table is seating on 6 tripods. Each tripod leg has 3 feet. They are supported by jack screws against copper plates on the concrete floor.                            These set screws allowed us to set the height,  level and distribute the load of the table.

To lock this position of the table grouting is used around the jack screws and between the concrete floor and the tripod feet.

Once the grout set the load will be carried by the hole feet  of 4" x 3.25" x3 = 39 sq inches per tripod leg

These ~4" thick grouted islands of 8-9" OD will be covered by 4" concrete. The area between the legs will be filled with 8" thick concrete.

http://www.fivestarproducts.com/techinfo/GroutHandbook.pdf

Atm1, http://www.fivestarproducts.com/cementgrouts/specsheets/grout_ss.pdf

Cement based grout, early height change 0 - 4%, hardened height change 0 - 0.3%

Atm2-3,  pouring grout

Atm4,  south west leg is done

Tomorrow: setting up ribbed bars, building frame to hold concrete and pour concrete

Attachment 1: P1060687.JPG
Attachment 2: P1060681.JPG
Attachment 3: P1060686.JPG
Attachment 4: P1060696.JPG
7150   Fri Aug 10 21:37:15 2012 DenUpdatePEMgur, sts noise

Using Guralp, STS-2 and Trillium I compared Gur and STS-2 self-noise assuming that Trillium noise is not worse then STS-2 noise.

Interesting that STS-2 (or Trillium if its noise is worse) noise is not too much better then Guralp noise.

6536   Mon Apr 16 09:10:37 2012 DenUpdatePEMgur2_x

Already not for the first time I notice that GUR2 readjusts its X zero position

As a result the coherence between GUR1X and GUR2X is lost, but between GUR2X and GUR2Y shows up. It seems that these two signals mix at some point.

6537   Mon Apr 16 09:44:54 2012 JenneUpdatePEMgur2_x

 Quote: Already not for the first time I notice that GUR2 readjusts its X zero position As a result the coherence between GUR1X and GUR2X is lost, but between GUR2X and GUR2Y shows up. It seems that these two signals mix at some point.

Can you go back in time before the X-position jumped to plot the x1-x2 and x2-y2 coherences?  Just to see what things look like?

6538   Mon Apr 16 14:37:01 2012 DenUpdatePEMgur2_x

Quote:

 Quote: Already not for the first time I notice that GUR2 readjusts its X zero position As a result the coherence between GUR1X and GUR2X is lost, but between GUR2X and GUR2Y shows up. It seems that these two signals mix at some point.

Can you go back in time before the X-position jumped to plot the x1-x2 and x2-y2 coherences?  Just to see what things look like?

DAQ is not working now but ordinary the coherence between GUR1X and GUR2X is ~1 at 0.1 - 10 Hz and between GUR2X and GUR2Y is ~0.

6721   Wed May 30 22:51:32 2012 DenUpdatePEMguralp isolation box

When I've put Guralps inside the isolation box, the signal from seismometers increased and was out of AA board range. I've reduced the gain of the readout box by a factor of 2. Now R2 for channels 1-6 is (2000, 1050, 1050, 2000, 1050, 1050) Ohm.

The signal increased in the frequency range 30-50 Hz. Guralp noise become better. That's good. However, it is still worse then in the manual.

As Yuta is dancing on the isolation box, Guralp signal is most time out of the AA board range. So I calculated the noise based on 5 min data. This may be enough, but I'll repeat the experiment later with 30 min data.

6696   Tue May 29 00:35:57 2012 DenUpdatePEMguralp readout box

I measured the frequency response of the Guralp readout box and noise by providing sin signal of amplitude 50 mV at 15 Hz for channels 1-3.

It turns out that the gain is ~250, while my liso model simulated it to be 200. This is because it is hard to approximate AD620 amplifier.

Noise of the box does not seem to be too bad at low frequencies.

6618   Mon May 7 21:46:10 2012 DenUpdateCDSguralp signal error

GUR1_XYZ_IN1 and GUR2_XYZ_IN1 are the same and equal to GUR2_XYZ.  This is bad since GUR1_XYZ_IN1 should be equal to GUR1_XYZ.  Note that GUR#_XYZ are copies of GUR#_XYZ_OUT, so there may be (although there isn't right now) filtering between the _IN1's and the _OUT's.  But certainly GUR1 should look like GUR1, not GUR2!!!

Looks like CDS problem, maybe some channel-hopping going on? I'm trying a restart of the c1sus computer right now, to see if that helps.....

Figure:  Green and red should be the same, yellow and blue should be the same.  Note however that green matches yellow and blue, not red.  Bad.

6757   Tue Jun 5 21:09:40 2012 yutaUpdateComputer Scripts / Programshacked ezca tools

Currently, ezca tools are flakey and fails too much.
So, I hacked ezca tools just like Yoichi did in 2009 (see elog #1368).

For now,

/ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcastep
/ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcaswitch
/ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcawrite

are wrapper scripts that repeats ezca stuff until it succeeds (or fails more than 5 times).

Of course, this is just a temporary solution to do tonight's work.
To stop this hack, run /users/yuta/scripts/ezhack/stophacking.cmd. To hack, run /users/yuta/scripts/ezhack/starthacking.cmd.

Original binary files are located in /ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcabackup/ directory.
Wrapper scripts live in /users/yuta/scripts/ezhack directory.

I wish I could alias ezca tools to my wrapper scripts so that I don't have to touch the original files. However, alias settings doesn't work in our scripts.
Do you have any idea?

6768   Wed Jun 6 18:04:22 2012 JamieUpdateComputer Scripts / Programshacked ezca tools

 Quote: Currently, ezca tools are flakey and fails too much. So, I hacked ezca tools just like Yoichi did in 2009 (see elog #1368). For now, /ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcaread /ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcastep /ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcaswitch /ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcawrite are wrapper scripts that repeats ezca stuff until it succeeds (or fails more than 5 times). Of course, this is just a temporary solution to do tonight's work. To stop this hack, run /users/yuta/scripts/ezhack/stophacking.cmd. To hack, run /users/yuta/scripts/ezhack/starthacking.cmd. Original binary files are located in /ligo/apps/linux-x86_64/gds-2.15.1/bin/ezcabackup/ directory. Wrapper scripts live in /users/yuta/scripts/ezhack directory. I wish I could alias ezca tools to my wrapper scripts so that I don't have to touch the original files. However, alias settings doesn't work in our scripts. Do you have any idea?

I didn't like this solution, so I hacked up something else.  I made a new single wrapper script to handle all of the utils.  It then executes the correct command based on the zeroth argument (see below).

I think moved all the binaries to give them .bin suffixes, and the made links to the new wrapper script.  Now everything should work as expected, with this new retry feature.

controls@rosalba:/ligo/apps/linux-x86_64/gds-2.15.1/bin 0$for pgm in ezcaread ezcawrite ezcaservo ezcastep ezcaswitch; do mv$pgm{,.bin}; ln ezcawrapper $pgm; done controls@rosalba:/ligo/apps/linux-x86_64/gds-2.15.1/bin 0$ cat ezcawrapper
#!/bin/bash

retries=5

pgm="$0" run="${pgm}.bin"

if ! [ -e "$run" ] ; then cat <&2 This is the ezca wrapper script. It should be hardlinked in place of the ezca commands (ezcaread, ezcawrite, etc.), and executing the original binaries (that have been moved to *.bin) with$retries
failure retries.
EOF
exit -1
fi

if [ -z "$@" ] || [[ "$1" == '-h' ]] ; then
"$run" exit fi for try in$(seq 1 "$retries") ; do if "$run" "$@"; then exit else echo "retrying ($try/$retries)..." >&2 fi done echo "$(basename $pgm) failed after$retries retries." >&2
exit 1


6769   Wed Jun 6 18:22:52 2012 JamieUpdateComputer Scripts / Programshacked ezca tools

 Quote: I didn't like this solution, so I hacked up something else.  I made a new single wrapper script to handle all of the utils.  It then executes the correct command based on the zeroth argument (see below). I think moved all the binaries to give them .bin suffixes, and the made links to the new wrapper script.  Now everything should work as expected, with this new retry feature.

Yuta and I added a feature such that it will not retry if the environment variables EZCA_NORETRY is set, e.g.

8068   Tue Feb 12 18:25:43 2013 JamieSummaryGeneralhalf PRC with astigmatic PR2/3

Quote:
 arbcav a la mode measurement g tangential 0.9754 0.9753 0.986 +/- 0.001 g sagital 0.9686 0.9685 0.968 +/- 0.001

Given that we're measuring different g parameters in the tangential and sagittal planes, I went back to alamode to see what astigmatism I could put into PR2 and/or PR3 to match what we're measuring.  I looked at three cases: only PR2 is astigmatic, only PR3 is, or where we split the difference.  Since the sagittal measurement matches, I left all the sagittal curvatures the same in

### case 1: PR3 only

 PR2 RoC (m) PR3 RoC (m) g (half PRC) tangential 706 -420 0.986 sagittal 706 -700 0.969

### case 2: PR3 only

 PR2 RoC (m) PR3 RoC (m) g (half PRC) tangential 5000 -700 0.986 sagittal 706 -700 0.969

### case 3: PR2 and PR3

 PR2 RoC (m) PR3 RoC (m) g parameter tangential 2000 -600 0.986 sagittal 706 -700 0.969

From Koji's post about the scans of the G&H mirrors, it looks entirely reasonable that we could have these levels of astigmatism in the optics.

## What this means for full PRC

These all make the same full PRC situation:

g (tangential):  0.966

g (sagittal):  0.939

ARM mode matching:  0.988

1165   Mon Dec 1 15:09:27 2008 robUpdatePEMhalf-micron particle count is alarming
1168   Tue Dec 2 19:51:32 2008 ranaUpdatePEMhalf-micron particle count is alarming
The 0.5 micron dust monitor count is now pretty high (36000). I wandered around the lab to see if there was anything
nasty going on but I didn't see or smell anything in particular. Since today Alberto was sitting around where the
dust monitor is while aligning the PSL beam, we should blame him. Its either garlic, cologne, or time to bathe.

The 400 day hour trend shows that while the counts are not so unusual, the 40m is dirtier than it was last year.
Attachment 1: Untitled.png
Attachment 2: dust.png
9970   Mon May 19 09:19:44 2014 SteveUpdateLSChappy IFO

15 hours

Attachment 1: whenthinksareworking.png
10858   Tue Jan 6 10:04:39 2015 SteveUpdateIOOhappy IOO
Attachment 1: IOO.png
11886   Wed Dec 16 10:56:22 2015 gautamUpdateCDShard reboot of FB

[ericq,gautam]

Forgot to submit this yesterday...

While we were trying to get the X-arm locked to IR using MC2, frame-builder mysteriously crashed, necessitating us having to go down to the computer and perform a hard reboot (after having closed the PSL shutter and turning all the watchdogs to "shutdown"). All the models restarted by themselves, and everything seems back to normal now..

1622   Fri May 22 17:05:24 2009 rob, peteUpdateComputershard reboot of vertex suspension controllers

we did a hard reboot of c1susvme1, c1susvme2, c1sosvme, and c1susaux.  We are hoping this will fix some of the weird suspension issues we've been having (MC3 side coil, ITMX alignment).

88   Fri Nov 9 09:37:55 2007 steveUpdatePSLhead temp hiccup
Just an other PSL-126MOPA_HTEMP hiccup.
The water chiller is at 20.00C
1116   Thu Nov 6 09:45:27 2008 steveUpdateMOPAhead temp hick-up vs power
The control room AC temp was lowered from 74F to 70F around Oct 10
This hold the head temp rock solid 18.45C for ~30 days as it shows on this 40 days plot.

note: the laser chiller did not produce any water during this period
Attachment 1: htpr.jpg
911   Tue Sep 2 10:09:03 2008 steveUpdatePSLhead temp is cooling down
The chiller was over flowing this morning.
800 cc of water was removed.
PSL-126MOPA_HTEMP peaked at 20.7 C (normal is 18.7 C)
13269   Tue Aug 29 15:41:17 2017 KiraSummaryPEMheater circuit

I worked with Kevin and Gautam to create a heater circuit. The first attachment is Kevin's schematic of the circuit. The OP amp connects to the gate of the power MOSFET, and the power supply connects to the drain, while the source goes into the heater. We set the power supply voltage to 22V and varied the voltage of the input to the OP amp. At 6V to the OP amp, we got a current of 0.35A flowing through the heater and resistor. This was the peak current we got due to the OP amp being saturated (an increase in either of the power supplies did not change the current), but when we increased the voltage of the supply rails of the OP amp from 15V to 20V, we got a current of 0.5A. We would want a higher current than this, so we will need to get a different OP amp with a higher max voltage rating, and a resistor that can take more power than this one (it currently takes 5W of power, and is the best one we could find).

Kevin and I created a simulation of this circuit using CircuitLab to understand why the current was so low (second attachment). The horizontal axis is the voltage we supply to the OP amp. The blue line shows the voltage at the point between the output of the OP amp and the gate of the MOSFET. The orange line is the voltage at the point between the source of the MOSFET and the heater. The brown line is the voltage at the point between the heater and resistor. Thus, we can see that saturation occurs at about 2.1V. At that point, the gate-source voltage is the difference between the blue curve and the orange curve, which is about 4V, which is what we measured. Likewise, the voltage across the heater is the difference between the orange curve and the brown curve, which comes out to around 8V, which is also what we measured. Lastly, the voltage across the resistor is the brown curve, which is about 2V, which matches our observations. The circuit works as it should, but saturates too soon to get a high enough current out of it.

Gautam noted that it is important to measure the current correctly. We can't just use an ammeter and place it across the resistor or heater, because the internal resistance of the ammeter (~0.5 ohm) is comparable to the resistance we want to measure, so the current gets split between the circuit and the ammeter and we get an equivalent resistance of 1/R = 1/R0 + 1/Ra, where R0 is the resistance of the part we want to measure the current across, and Ra is the ammeter resistance. Thus, the new resistance will be lower and the ammeter will show a higher current value than what is actually there. So to accurately measure the current, we must place the ammeter in series with the part we want to measure. We initially got a 1A reading on the heater, which was not correct, and our setup did not heat up at all basically. When we placed the ammeter in series with the heater, we got only 0.35A.

The last two images are the setup for testing of the heater. We wrapped it around an aluminum piece and covered it with a few layers of insulating material. We can stick a thermometer in between the insulation and heater to see the temperature change. In later tests, we may insulate the whole piece so that less heat gets dissipated. In addition, we used a heat sink and thermal paste to secure the MOSFET to it, as it got very hot.

Our next steps will be to get a resistor and an OP amp that are better suited for our purposes. We will also run simulations with components that we choose to make sure that it can provide the desired current of 1A (the maximum output of the power supply is 24V, and the heater is 24 ohm, so max current is 1A). Kevin is working on that now.

Attachment 1: heater_circuit.pdf
Attachment 2: simulation.png
Attachment 3: heater_setup.jpg
Attachment 4: IMG_20170829_131126.jpg
13292   Tue Sep 5 09:47:34 2017 KiraSummaryPEMheater circuit calculations

I decided to calculate the fluctuation in power that we will have in the heater circuit. The resistors we ordered have 50 ppm/C and it would be useful to know what kind of fluctuation we would expect. For this, I assumed that the heater itself is an ideal resistor that has no temperature variation. The circuit diagram is found in Kevin's elog here. At saturation, the total resistance (we will have a $1\Omega$ resistor instead of $6\Omega$ for our new design) will be $R_{tot}=R+R_{h}=1\Omega +24\Omega =25\Omega$. Therefore, with a 24V input, the saturation current should be $I=\frac{V_{in}}{R_{tot}}=\frac{24V}{25\Omega}=0.96A$.  Therefore, the power in the heater should be (in the ideal case) $P=I^2R{_{h}}=22.1184W$

Now, in the case where the resistor is not ideal, let's assume the temperature of the resistor changes by 10C (which is about how much we would like to heat the whole thing). Therefore, the resistor will have a new value of $R_{new}=R+50ppm/C\times 10C\times 10^{-6}=1.0005\Omega$. The new current will then be $I_{new}=\frac{V_{in}}{R_{new}}=0.95998A$ and the new power will be $P_{new}=I_{new}^{2}R_{h}=22.1175W$. So the difference in power going through the heater is about 0.00088W.

We can use this power difference to calculate how much the temperature of the metal can we wish to heat up will change. $\Delta T=\Delta P\times (1/\kappa) /x$ where $\kappa$ is the thermal conductivity and x is the thickness of the material. For our seismometer, I calculated it to be 0.012K.

6116   Wed Dec 14 12:18:11 2011 ZachUpdateRF Systemheater reengaged

I reengaged the heater this morning, to compare it with the free-wafting and passive box-covered data. In order to make the loop stable, I had to reduce the gain of the AD620 by 10. I have increased the TEMP_MON preamp gain by 10, so the calibration should still be ~3.5 V/K into the ADC (and in DV).

Below is a screenshot showing that the RAMmon signals are pushed to some (nonzero) value, and it appears that they stay there despite the changing PSL table temperature as measured by FSS_RMTEMP. My post from last week shows that without the heater servo the temperature of the EOM can follows RMTEMP almost exactly. So, it seems like the heater is working well at low frequencies, modulo sensor noise, which ought to be low for the thermistor. Since several things (MC, etc.) have changed since out baseline data, it migth be prudent to let this sit for a little while and then disconnect the heater to see what happens.

14105   Thu Jul 26 01:52:01 2018 terraUpdateThermal Compensationheater work update

Just a quick update: over the past few days we've taken (at least) 5 scans around each peak [carrier - HOM3] at 9.4V/0.8A, 4 scans around [carrier - HOM5] at 12V/0.9A hot state with the reflector setup. We also have (at least) 5 scans of carrier - HOM5 in cold state. I attach a rough overview of the peak magnitude shifts in the first attachment. Analysis ongoing. All data stored in annalisa/postVent/{date}

Initial shifts just based on rought peak placement in the meantime:

[9.4V/0.8A]   [12V/0.9A]

HOM1    10 kHz         20 kHz

HOM2    18 kHz         28 kHz

HOM3     30 kHz        40 kHz

HOM4     N/A             26 kHz

HOM5     N/A             35 kHz

I also attach the heating thermal transient from today (12V/0.9A) as seen by the opLevs. We see a shorter time constant for pitch, longer for yaw, preceeded by a dip in yaw. Similar behavior yesterday for slightly less heating, though less pronounced pre-dip. The heater is offcentered on the optic horizontally; likely this is part of the induced yaw. The spikey stuff i removed is from people walking around inside during the transient.

I've left the heater and LSC off for the night. Heater off at 2:07 am local time.

Please don't touch the oplevs; we're taking a cool down measurement.

Attachment 1: OpLev_thermal_drift.pdf
Attachment 2: hotColdAll.pdf
9499   Fri Dec 20 01:24:11 2013 DenUpdateLSChigh bandwidth loop achieved for yarm

Koji, Den

CM Servo with POY11 successfully engaged. UGF: ~15kHz.

Tonight we decided to repeat one arm locking using high-bandwidth CM servo. We low-passed AO signal to avoid saturations of the EOM. We tried different configurations that compromise between noise and loop phase margin and ended up with a pole at 30kHz. SR560 is used as a low-pass filter.

Another problem that we faced was big (~2.6V) electronic offset at the input of 40:4000 BOOST. Once engaged, cavity would be kicked out of lock. We calibrated this offset to be almost half linewidth of the cavity (~300pm). To avoid lock loss during engaging the boost we increased common mode gain to maximum (31 dB).

Measured OL is attached. UGF is 15kHz, phase margin is 60 degrees. We have also simulated evolution of loop shape during bringing AO path. Plot is attached.

The final procedure is

• set common gain up to 31dB, AO gain to 8dB, MC IN2 gain 10dB, CM offset 0.7V
• lock arm with CM slow path with bandwidth of 200 Hz
• enable AO path, gradually increase slow and fast gains by 12 dB
• enable boost
Attachment 1: CM_OL_meas.pdf
Attachment 2: cm_ol_sim.pdf
Attachment 3: CM_slow_fast_cross.pdf
9501   Fri Dec 20 03:34:40 2013 KojiUpdateLSChigh bandwidth loop achieved for yarm

This too huge offset difference with/without "BOOST" switch should be checked.

9507   Fri Dec 20 22:45:02 2013 KojiUpdateLSChigh bandwidth loop achieved for yarm

I checked the offset situation in the CM servo boost circuit.

- The offset voltage on the CM servo screen is a raw DAC output. This number is diluted by the voltage divider before the amplifier.
So, the actual offset of the boost circuit was much smaller. (~20mV)

- There is a offset trimmer on the board. This was adjusted so that the boost does not generate an output offset.

- So the default offset is 0V.

- When the arm was locked with (digital) POY11, the CM servo offset is necessary to be -2.7 (now).
This means that analog POY11Q and digital POY11 has different offset for the best resonance transmission.
That is believable if POY11I is contributing to the digital POY11 signal.

7645   Wed Oct 31 14:31:34 2012 SteveUpdatePEMhigh particle count

High particle count confirmed with #2 counter

Attachment 1: highparticlec.png
7680   Wed Nov 7 11:43:29 2012 SteveUpdatePEMhigh particle count ALART

The BS camber is open only. We should close ASAP

Outside air quality is 1.7- 2.2  million particles  / cf min of 0.5 micron

Attachment 1: highpartcount.png
8001   Tue Feb 5 10:18:54 2013 SteveUpdatePEMhigh particle count ALART

Quote:

 Quote: The BS camber is open only. We should close ASAP Outside air quality is 1.7- 2.2  million particles  / cf min of 0.5 micron

Air is still bad and the chambers are closed. Before lunch  Jamie repointed the PRM oplev. Manasa and I reset oplevs: BS and ITMX.

ETMX and ETMY are fine.

SRM and ITMY oplevs needs more work.

The bad outside air quality is pushing up the inside counts.

The outside air is 5 million counts / cf min for 0.3 micron and 2 million counts / cf min for 0.5 micron particles

Do not open chamber over 10,000 counts / cf min of 0.5 micron

Attachment 2: 100d_airq.png
7681   Wed Nov 7 14:59:35 2012 SteveUpdatePEMhigh particle count ALART & oplevs

 Quote: The BS camber is open only. We should close ASAP Outside air quality is 1.7- 2.2  million particles  / cf min of 0.5 micron

Air is still bad and the chambers are closed. Before lunch  Jamie repointed the PRM oplev. Manasa and I reset oplevs: BS and ITMX.

ETMX and ETMY are fine.

SRM and ITMY oplevs needs more work.

Attachment 1: oplevs.png
2370   Wed Dec 9 09:07:32 2009 steveUpdatePEMhigh seismic activity

The construction activity is shaking the tables in the control room.  The compactor- large remote controlled jackhammer is in the bottom of the 16-17 ft deep hole 15 ft east of ITMY in CES bay. The suspensions  are holding OK. PRM, MC1 and MC3 are effected mostly.

Attachment 1: seis24d.png
Attachment 2: seis4h.png
Attachment 3: P1050833.JPG
Attachment 4: P1050836.JPG
4405   Fri Mar 11 16:30:42 2011 steveUpdateGeneralhigh speed servo unit is here

New Focus Servo Controller has just arrived. We have 25 days to evaluate this product.

It will have to be shipped back to the vendor on April 4, 2011 the latest in order to get full refund.

Attachment 1: P1070462.JPG
12888   Tue Mar 14 15:05:18 2017 SteveUpdateOptical Levershistory of ETMX oplev laser

 Quote: ETMX oplev laser is dead. It will be replaced this after noon. Sus damping recovered.

This 3 years old HeNe [ JDS 1103P, sn 351889 ]  has been dying for some time or just playing possum at age 1,126 days

I did not replace the ETMX oplev laser because I was unable to bring up the the C1ASC_ETMX_OPTLEV_SERVO  medm screen on laptops.

Attachment 1: ETMX_1103P_3y.png
2151   Tue Oct 27 18:01:49 2009 robUpdatePSLhmmm

A 30-day trend of the PCDRIVE from the FSS.

Attachment 1: pcdrive_trend.png
1004   Mon Sep 29 11:17:14 2008 steveUpdateSAFETYhorizontal viewports are protected with lexan
The four horizontal viewports of arms are protected
by 3/8" thick, 8.5" OD Lexan disk of MR10 Polycarbonate.

ITMX, ETMX, ITMY and ETMY ccd cameras are not focused now.
12616   Tue Nov 15 19:22:17 2016 gautamUpdateGeneralhousekeeping

PRM and SRM sat. boxes have been switched for some time now - but the PRM sat. box has one channel with a different transimpedance gain, and the damping loops for the PRM and SRM were not systematically adjusted to take this into account (I just tweaked the gain for the PRM and SRM side damping loops till the optic damped). Since both sat. boxes are nominally functioning now, I saw no reason to maintain this switched configuration so I swapped the boxes back, and restored the damping settings to their values from March 29 2016, well before either of this summer's vents. In addition, I want to collect some data to analyze the sat. box noise performance so I am leaving the SRM sat. box connected to the DAQ, but with the tester box connected to where the vacuum feedthroughs would normally go (so SRM has no actuation right now). I will collect a few hours of data and revert later tonight for locking activities....

6306   Wed Feb 22 19:45:33 2012 kiwamuUpdateLSChow much length offset do we need ?

I did a quick calculation to see if the offset of the arm length which I tried last night was reasonable or not.

The conclusion is that the 20 nm offset that i tried could be a bit too close to a resonance of the 55 MHz sidebands.

A reasonable offset can be more like 10 nm or so where the phases of all the laser fields don't get extra phases of more than ~ 5 deg.

The attached plot shows where the resonances are for each sideband as a function of the displacement from the carrier's resonance.

The red solid line represent the carrier, the other solid lines are for the upper sidebands and the dashed lines are for the lower sidebands.

The top plot shows the cavity power and the bottom plot shows how much phase shift the fields get by being reflected by the arm cavity.

Apparently the closest resonances to the the main carrier one are that of the 55 MHz sidebands, and they are at +/- 22 nm.

So if we displace the arm length by 22 nm, either of the 55 MHz sidebands will enter in the arm cavity and screw up the sensing matrix for the 55 MHz family.

 Quote from #6304 In all the configurations I displaced the Y arm by 20 nm from the resonance.

4356   Fri Feb 25 10:11:56 2011 steveUpdateSAFETYhow not to

The beam of IR for doubling  is clipping on bnc cable to green beam transmitted pd.

Attachment 1: Presentation1.jpg
4953   Thu Jul 7 13:57:28 2011 steveHowToSAFETYhow not to

I found baked allen keys on the top of the clean optics cabinet.  Somewhat heavy box that can come down in an earthquake on our heads.

NOTHING SHOULD GO ON THE TOP OF THE CABINETS OR RACKS except  small plastic boxes that storing our clean clothing.

9027   Mon Aug 19 10:03:17 2013 SteveHowToGeneralhow not to leave a cable

We can not leave cables connected like this. This is a burned toast award.

Attachment 1: NONOcable.jpg
7864   Thu Dec 20 17:13:56 2012 JamieUpdateGeneralhow to deal with problem with in-vac wiring for TTs

So this is obviously a general problem for all the TTs.  Our in-vacuum wiring is unfortunately mirrored relative to that of aLIGO, or at least:

• aLIGO: in-vacuum pin 1 tied to shield (T1200131)
• 40m: in vacuum pin 13 tied to shield

And again, the problem is that pin 13 on the TT quadrapus cables is the one of the coil pins for one of the OSEMs.

I think the right solution is to make mirroring adapter cables for the TTs.  Modifying the pins on the stack-top brackets for just the TTs would leave us with a bunch of brackets that are different than all the rest, which I think is a bad idea.  Therefore we leave all the feed-thru-->bracket wiring the same, and make adapters.  I'll describe the adapters in a follow-up post.

The silver lining to this whole thing, if there is one, is that I wired the polarity on the out-of-vac adapter cable at the coil driver in such a way that the drive/send signal went to the grounded in-vac pin.  If I had by chance wired the polarity oppositely everything would probably have worked, except that the return for one of the coils would have gone through the cable shield and the chamber, rather than the return pin to the coil driver.  I'll let you image the problems that would have caused.

Making new adapters will take a little while, but I think we can proceed with the installation and alignment with a temporary setup in the mean time by taking advantage of the polarity I mention above.  We can temporarily swap the polarity so that we can drive current to the coil using pin 13.  This will allow us to complete the installation and do all the alignment.  Once the in-vac adapter cable arrives, we just put it in, fix the out-of-vac polarity, check that everything works as expected, and button up.

We'll pick up all this when we're back on Jan 7.  Steve will put in an order for the in-vac adapter cables ASAP.

I take full responsibility for this fuck up.  We've been unable to find any in-vac wiring diagrams, but I should have checked all of the wiring during the last vent so that we could have prepared for this ahead of time.  Sorry.

6876   Wed Jun 27 03:43:52 2012 yutaSummaryIOOhow to improve mode matching to arms

From the mode scan measurements of the arms(elog #6859), ~6% of mode-mismatch comes from 2nd-order mode. That means we have longitudinal mismatch.

Suppose every mirrors are well positioned and well polished with designed RoC, except for the MMT1-MMT2 length. To get ~6% of mode-mismatch, MMT1-MMT2 length should be ~28cm longer (or ~26cm shorter) than designed value.
I don't know whether this is possible or not, but if they are actually longer(or shorter), we should fix it on the next vent.
I found some related elog on MMT (see #3088).

RoC and length parameters I used is below. They maybe wrong because I just guessed them. Please tell me the actual values.
Mirror thickness and effect of the incident angle is not considered yet.

== RoCs ==
MC2 19.965 m (???)
PRM 115.5 m (not used in calculation; just used to guess MC parameters)
ITM flat
ETM 57.37 m

== Lengths ==
MC round trip 27.084 m (???)
MC1 - MC3  0.18 m (???)
MC3 - MMT1 0.884+1.0442 m
MMT1 - MMT2 1.876 m
MMT2 - PRM 2.0079+0.4956 m
PRM - ITM 4.4433+2.2738 m
ITM - ETM 39 m

6877   Wed Jun 27 10:27:09 2012 ranaSummaryIOOhow to improve mode matching to arms

The MC waist is correct as is the arm RoCs. Most likely the error is in the telescope length or its distance from the MC. Jenne probably has all the numbers and can give us a surface plot showing how the MM degrades as a function of those two parameters.

2164   Fri Oct 30 09:24:45 2009 steveHowToMOPAhow to squeeze more out of little

 Quote: Here is the plots for the powers. MC TRANS is still rising. What I noticed was that C1:PSL-FSS_PCDRIVE nolonger hit the yellow alert. The mean reduced from 0.4 to 0.3. This is good, at least for now.

Koji did a nice job increasing light power with some joggling.

Attachment 1: 44to34.jpg
4960   Mon Jul 11 14:03:37 2011 steveHowTolorehow to visit your old lab

Alberto is visiting us from Australia. He brought some terrific presents. It is going to be very demanding task to wait for the rest of the 40m team

to return from Wales to taste coffee:  PNG Peaberry of Wagonga, Monsooned Malabar of Jindebah and Signature Blue Blend of Cosmorex.

Attachment 1: P1080069.JPG
709   Mon Jul 21 19:48:57 2008 SharonUpdate how tp restart C1ASS
How to restart C1ASS:

1. reboot
2. as root: caltech/target/c1ass:> ./startass
3. no need for root: burtgooey

that's it...
ELOG V3.1.3-