We aligned and locked x and y arms.
MCL loop makes arms lock unstable, adds a lot of noise at frequencies 60-100 Hz. We'll fix it.
At some point we were not able to lock because of ADC overflows of PO signals. They happened if whitening filters were enabled. So we reduced the gain of POX whitening filters down to 36 dB and POY - to 39 dB. Now cavities can be locked with whitening filters.
Also we changed the pedestal of the lens in the beam path to the POX because the beam was too high.
Also ordered 1 ea.
IR 780nm 3mW
The $1000 HeNe should not be used for illuminating fibers.
You should purchase these (total price per laser less than $6):
HeNe 1103P 2mW Recertified
(Koji, Suresh, Yuta)
We need MC to be locked and aligned well to align other in-vac optics.
By using a new python script A2L.py(see elog #3863), we are measuring A2L coupling and centering the beam.
Tonight's goal was to reduce common mode displacement of the beam through MC1 to MC3, and we succeeded.
Strategy of beam centering:
We first ignore the beam position at MC2 and focus on MC1,MC3. If MC1,MC3 alignments are given, MC2 alignment is determined.
For MC1 and MC3, we first reduce the common mode displacement using the last steering mirror at PSL table.
The last steering mirror makes translation of the incident beam because it is far (~m) from the MC.
1. Rotate the steering mirror nob a little
2. Lock MC so that MC beam axis will be the same as the incident beam axis
3. A2L measurement
4. To 1-3 over until the beam crosses MC1 center to MC3 center axis
The amount of vertical/horizontal displacements of the beam spot at MC1 and MC3 should be the same.
From our convention, for vertical, MC1 and MC3 should have opposite sign. For horizontal, same sign. (see picture below)
From the A2L measurement, now the beam spot is lower right at MC1 and upper right at MC3.
The directions of the beam spot motion agree with the steering mirror tilts.
Also, the amount of the motion seems reasonable.
1 tooth rotation of the steering mirror nob makes ~1e-3 inch push which equals to ~0.5mrad rotation.
The steering mirror to MC is like ~2m and 0.5mrad mirror tilt makes ~2mm displacement at the MC optics.
2mm displacement is ~15% at the mirror (see Koji's elog #2863;note that coil-coil distance is 1/sqrt(2) of the mirror diameter).
The measured vertical spot motion is ~15%/1tooth. Horizontal is sqrt(2) times bigger because of the angle of the MC1, MC3 and they are about that much, too.
- Use IM1 to make beam tilt and finally center the beam
- Improve the script so that it features weighting in fitting
- Write a script that balances actuation efficiency of the 4 coils.
We are currently assuming that 4 coils are well balanced.
In order to do the balancing, we need to balance OSEMs too.
The last entry I found relating to ref cavity was 2011 Aug 19
The ref cavity ion pump was running at 7.7kV instead of 5kV
This Digitel SPC-1 20 l/s ion pump should be running at 5kV
I noticed that the ion pump was turned off.
It was turned ON. It showed 0.00 microA at 5kV The current display is not sensitive enough. There must be some small outgassing or leak. It adds up if we stop pumping.
We want to keep the reference cavity in pristine condition. It required the ion pump running all times.
The PSL Temperature Box (D980400-B-C, what kind of numbering scheme is that?) modified at LHO/LLO ~8 years ago to have better resolution on the in-loop temperature sensors.
I haven't been able to find a DCN / ECN on this, but there's an elog entry from Hugh Radkins here. I'm also attaching the PDF of the latest drawing (circa 2000) from the DCC.
The schematic doesn't show it, but I am guessing that the T_SENSE inputs are connected to the AD590 chips, and that 4 of these are attached somehow to the RefCav can. IF this is true, I don't understand why there are input resistors on the LT1125 of U1; the AD590 is supposed to be a current source ?
Peter King is supposed to be coming over to work on this today so whoever spots him should force/cajole/entice him to elog what he's done. Film him if necessary.
I also think R1-8 should be swapped into metal film resistors for stability. The datasheet says that it puts out 1 uA/K, so the opamps put out 10 mV/K.
J8 and JP1 should be shorted to disable both the tidal and VME control input. Both are unused and a potential source of drift.
Peter King is updating our temp box as Hugh did at Hanford Oct.22 of 2001 I still have not seen an updated drawing of this.
The LT 1021-7 reference chip will arrive tomorrow morning. This modification should be completed by noon.
** The link to the DCN from Hugh is here in the DCC.
Is that the reason of the PSL craziness tonight? See attachment.
There's no elog entry about what work has gone on today, but it looks like Peter took apart the reference cavity temperature control around 2PM.
I touched the reference cavity by putting my finger up underneath its sweater and it was nearly too hot to keep my finger in there. I looked at the heater power supply front panel and it seems that it was railed at 30 V and 3 A. The nominal value according to the sticker on the front is 11.5 V and 1 A.
So I turned down the current on the front panel and then switched it off. Otherwise, it would take it a couple of days to cool down once we get the temperature box back in. So for tonight there will definitely be no locking. The original settings are in the attached photo. We should turn this back on with its 1A setting in the morning before Peter starts so that the RC is at a stable temp by the evening. Its important NOT to turn it back on and let it just rail. Use the current limit to set it to 1 A. After the temperature box is back in the current limit can be turned back up to 2A or so. We never need the range for 3A, don't know why anyone set it so high.
While Peter King is still working on the reference cavity temperature box, I turned the power supply for the reference cavity's heater back on. Rana turned it off last night since the ref cav temperature box had been removed.
I just switched it on and turned the current knob in the front panel until current and voltage got back to their values as in Rana's picture.
I plan to leave it like that for half an hour so that the the cavity starts warming up. After that, I'll turn the current back to the nominal value as indicated in the front panel.
It turned out that half an hour was too long. In less than that the reference cavity temperature passed the critical point when the temperature controller (located just below the ref cav power supply in the same rack) disables the input power to the reference cavity power supply.
The controller's display in the front shows two numbers. The first goes with the temperature of the reference cavity; the second is a threshold set for the first number. The power supply gets enabled only when the first number comes under the threshold value.
Now the cavity is cooling down and it will take about another hour for its temperature to be low enough and for the heater power supply to be powered.
The cavity temp cooled below SP2 set point 0.1 The Minco SP1 (present temp in Volts) now reading -0.037 so DC power supply was turned on and set to 12V 1A
First aid kits are located close vicinity of entry doors and under circuit breaker panels.
Mode matching to the cavity has been done.
Now the reflection from the cavity is successfully going into the PD.
However I could not see any obvious error signal.
I should compute and re-check the expected signal level.
(mode matching of the crystal)
On the last Wednesday, Kevin and I measured the mode profile before the PPKTP crystal, and we found the Gaussian beam at the crystal is focused too tightly (w = 38 um).
In order to achieve the best conversion efficiency the waist size should be 50.0 um. So we moved a lens, which was located before the crystal, to 7 cm more away from the crystal. Eventually we obtained a better focus (w = 50.1 um).
Thanks, Kevin. You did a good job.
(mode matching of the cavity)
I put a lens with f=-50 mm after the crystal to diverge the green beam more quickly. Then the beam is going through the Faraday of 532 nm, two final modematching lenses and ETMY at last.
By shifting the positions of these lenses, I obtained the reflection from ITMY with almost the same spot size as that of the incident. This means modemathing is good enough.
I put two more steering mirrors before its injection to the ETM, this allows us to align the beam axis against the cavity.
I aligned the axis by using the steering mirrors and now the green beam are successfully hitting the center of both the ETM and the ITM.
Then the alignment of the ETM and the ITM was adjusted from medm, so that both reflection goes in the same path as that of the incident.
And then I put a PD (Thorlabs PDA36A) to see the reflection rejected by the Faraday.
Connecting a mixer and a local oscillator (Stanford func. generator) with f=200kHz, but I couldn't see any obvious PDH signal....
Since the PD is DC coupled, the signal is almost dominated by DC voltage. Even if I inserted a high pass filter to cut off the DC, the AC signal looks very tiny..
Don't make a short cut. The beam size at a single place does not tell you anything.
Measure the mode of of the beam at multiple points. Calculate the mode matching ratio.
Align the mirrors precisely. Try to see the DC fringe. Predict the size of the DC fringe.
Test the demodulation system with a function generator. Find the 200kHz signal using the spectrum analyzer to find the signal and the optimal alignment.
Put the DC signal and the AC signal to the oscilloscope as X&Y.
Schott, Athermal green welding glass, shade #14 reflectivity was measured in 1.2W, ~1 mm diameter beam of MC reflected.
The P polarization measurement was done with the help of half wave plate and PBC
Alex has created a 2.4 branch of the RCD. Jamie, we can try to compile and install it. As a test a did it for c1oaf, it compiles, installs and runs once variables SITE, IFO, RCD_LIBRARY_PATH are properly defined. As we do not want to run one model at 2.4 code and others at 2.1, I recompiled c1oaf back to 2.1. Jamie, please, let me know when you are ready to upgrade to 2.4 release.
I released/updated my secret scripts to real scripts directory.
I checked they run correctly (but maybe not working correctly).
It returns a value of a specified channel in the past using burt snapshots.
Help is available.
Toggles green shutter until it locks TEM00.
Help is available. Threshold setting is critical.
Beeps when MC is unlocked.
Python library for data loading, saving and plotting.
I think it's well commented.
Python library for ezca stuff.
It has functions for recording and resetting default channel values in case of interrupt.
Python scripts for PRC modescan. Not well commented. Not organized.
See elog #8012
Python and shell scripts for alignment work. Not well commented.
See elog #8164
Python scripts for oplev calibration. Not well commented.
See elog #8221
Python scripts for g-factor measurement. Not well commented.
See elog #8230
Python scripts for calibrating actuators. Not well commented.
See elog #8242
Trying to download some data using matlab today, I found that my ole mDV stuff doesn't work because its MEX files were built for AMD64...
Tried to rebuild the NDS1 MEX according to 7 year old instructions didn't work; our GCC is 'too' new.
From the Remote Data Access wiki (https://wiki.ligo.org/RemoteAccess/MatlabTools) I got the new 'get_data.m' and 'GWdata.m'. These didn't run, so I updated the nds2-client and matlab-nds2-client on Donatella.
Still doesn't run to get 40m data. It recognizes that we're C1, but throws some java exception error. Maybe it doesn't work on the NDS1 protocol of our framebuilder?
So then I noticed that our NDS2 server on megatron is no longer running...thought it was supposed to run via init.d. Found that the nds2 binary doesn't run because it can't find libframecpp.so.5; maybe this was blown away in some recent upgrade? We do have versions 3, 4, 6, 7, & 8 of this library installed.
So now, after an hour or two, I'm upgrading the nds2 server on megatron (plus a hundred dependencies) as well as getting a newer version of matlab to see if there's some kind of java version issue there.
Of course python still works to get data, but doesn't have any of the wiener filter calculating code that matlab has...
NDS2 restarted after hours long upgrade process; testing has begun. Let's try to get some long stretches of MC locked with MCL FF ON this weekend so's I can test out the angular FF idea.
We disconnected the cable that was connected to CH5 of the whitening filter in 1Y2, then connected POYDC cable to there (CH5). This channel is where POYDC used to connect.
Then we turned on the whitening filter for POYDC (C1:LSC-POYDC FM1) and changed the gain of analog whitening filter for POYDC from 0 dB to 39 dB (C1:LSC-POYDC_WhiteGain).
The Mach-Zehnder on the PSL table was removed.
A path for 166 MHz modulation in the Mach-Zehnder (MZ) was completely removed, the setup for another path remains the same as before.
Also the photo detector and the CCD for the PMC transmittion were moved to behind the PZT mirror of PMC.
Before removing them, we put an aperture in front of the PD for MC REFL so that we can recover the alignment toward MC by using the aperture.
After the removal we tried to re-align the EOM which imposes the sideband of 29MHz for MC.
We eventually got good alignment of 97% transmissivity at the EOM ( the power of the incident beam is 1.193W and trans was 1.160W )
And then we aligned the beam going to MC by guiding the reflected beam to the aperture we put. This was done by using the steering mirrors on the periscope on the corner of the PSL table.
Now MC got locked and is successfully resonating with TEM00.
Yesterday we added some new control logic to the sus_single_control part to allow for global damping. Today we decided that a binary switch between local/global damping was probably a bit extreme since we might want to smoothly ramp between them, instead of just hard switching. So we removed this switch and are now just summing the control inputs from global and local damping right before the output matrix.
Changes were committed to the SVN, and all suspension models were recompiled/installed/restarted.
I removed the multiply resonant EOM that has been set by a SURF student from PSL table.
I will use it for checking the resonant circuit.
We missed to check that we had the green transmitted to the PSL after flipping the SRC and PRC folding mirrors.
There is no green transmission reaching the PSL even after locking the arms to green.
We should fix this tomorrow. The BS heavy door should come off.
Steve! Do not start pump down tomorrow !
We closed the chambers last night with heavy doors and reopened it today.
JDSU can repair the Lightwave M126-1064-700 NPRO, sn 415 They do not need the Controller sn 516
Posted in the 40m Wiki_ PSL_ NPRO cost repair and/or option to buy Innolight laser as replacement
The most recent power outage took out our projector and mixer. The projector was sent for repair while we ordered a new mixer. Both arrived today. Steve is working on re-installing the projector right now, and I installed the mixer which was verified to be working with our DAFI system (although the 60Hz issue still remains to be sorted out). The current channel configuration is:
Ch1: 3.5mm stereo output from pianosa
Ch2: DAFI (L)
Ch3: DAFI (R)
I've set some random gains for now, but we will have audio again when locking
[Rana, Jenne, Suresh]
Yesterday, We replaced the existing beam steering mirror and the PZT it was mounted on with a Gooch and Housego mirror (20ppm transmission at < 30deg incidence @1064nm) and a Polaris-K1 Newport steel mount. (JD)
We realigned the G&H mirror to get the MC flashing.
We then had to reduce the gain in the servo circuit to accommodate the increased optical power going into MC.
MC locked to PSL once again.
the old mirror stuck on the PZT has been removed. The mirror had no markings and has been stored in the 'Unknown Optics' Box along the East Arm.
The PZT has been stored in the PZT cabinet along with its 2in mirror mount.
Spent a lot of time aligning tonight. The BS is not staying put--sometimes after a lock loss it gets badly mis-aligned.
DD handoff is working, after putting beam on REFL diodes and running senseDRM script.
locking work proceeding apace tonight.
diagonalized DRM with setDDphases & senseDRM.
initial locks are fairly quick, aqstep script succeeds reliably.
first part of cm_step (handoff CARM-> MCL) usually works.
tuning up later parts of cm_step (presumably due to optical gain changes resulting from MOPA decline).
got to arm powers ~60.
1.The aim is the laser frequency stabilisation of PSL and AUX.
2.As a first step we want to couple some of the AUX laser beam into a single mode optical fibre and route the fibre to the PSL table.
3.The position of the optical fibre on the ETMY table is shown by the coupler in the attached picture. The yellow lines show the new scheme we want to implement.
4.WHAT WE DID TODAY.
rob, alberto, rana, pete
we reset this computer, which was out of sync (16384 in the FE_SYNC field instead of 0)
Q and Steve will follow elog 10028 entry to prepare the vacuum system for safe reboot
Here's the sequence of the morning so far:
The IFO is still down, as the PMC won't lock without the rack power, and we haven't pinned down the shorting mechanism. We don't want the replacement sorensen to immediately blow when plugged in.
Smoking Sorensen could have triggered the smoke alarm!
Yesterday I called CIT Fire Protection Services very first to deactivate the sensors temporarily. The smoke alarm was turned back on right after the particle count dropped.
Their phone number is posted at the entry doors 104M and 104W as shown below.
More of the same.
Who is putting weird figures into the elog?!?! I haven't checked lately, but this is what usually crashes the elog. It's been happening a lot lately, and it might be the .pdf's.
Let's play a new game. We'll call this game "Everyone only use .png files for the next week" Ready? GO!
More of the same.
Do we know what causes the crashes for definite? Let's give the whole knowledge gathering a shot. Surfs welcome to post. Please follow the format and keep it brief. P.S. if the elog stops responding or hangs while you're trying to edit a post or write a post, you may have crashed it.
Edit this post to add your own experience using the above format
Restarted the elog using the script. I had to do it twice for it to work. This is not the first time this has happened---does anyone know why this might be?
took two again
Restarted the elog with the script
The process was taking up 100% of the CPU and not responding via web. The .log file showed the last action was somebody reading/editing one of Jenne's entries from August regarding TT ECD. The restart script didn't work, so I had to do a 'kill -9' to get it to die.
Did the same.
Did it again. It seemed that Google bot came to the elog and tried to obtain "http://nodus.ligo.caltech.edu:8080/robots.txt". That was the last of the log.
Bot came from the AJW's homepage. Also Google FeedFecther came to the elog.
I deleted the yellow box which showed up by default when making an elog entry. Would be nice if we could make it so that you have to click a button to 'opt-in' for the yellow box rather than get it by default.
I added a 'robots.txt' file to the /users/public_html/ area using Google's instructions (it only works with robot compliant crawlers), but am not sure how to put robots.txt into the elog port.