I went to re-align the beam into the PMC just now. I also tapped all the components between the laser and the PMC; nothing seems suspicious or loose.
The only problem was that someone (probably Steve or Valera) had closed down the iris just downstream of the AOM to ~1-2 mm diameter. This is much too tight! Don't leave irises closed down after aligning. An iris is not to b used as a beam dump. Getting it within a factor of 5-10 of the beam size will certainly make extra noise from clipping/scattering. After opening the iris, the reflected beam onto the PMC REFL camera is notably changed.
Not sure if this will have any effect on our worsening transmission drift, but let's see over the weekend.
I took pictures of this clipping as well as the beam position on Steve's new Retro Position Sensor, but I can't find the cable for the Olympus 570UZ. Steve, please buy a couple more USB data cables of this particular kind so that we don't have to hunt so much if one of the cryo (?) people borrows a cable.
Attachment shows PMC power levels before and after alignment. After alignment, you can see spikes from where I was tapping the mounts in the beamline. We ought to replace the U-100 mount ahead of the AOM with a Polanski
EDIT: Cryo team returns cable - receives punishments. Picture added.
I wonder what's drifting between the laser and the PMC? And why is it getting worse lately?
The PMC refl is bad in pitch today, and the transmission is only 0.76, rather than our usual 0.83ish.
I did a quick, rough tweak-up of the alignment, and now we're at 0.825 in transmission.
The PMC transmission continuously degrades. In order to see what is really drifting the laser output after PBS was sampled as shown.
IOO pointing is drifting in pitch. I'd like to use a QPD instead of the paper target to see if the Innolite output is stable. The idea is to move temporarily IOO-QPD_POS to this location
I do like to move IOO-QPD_POS temporarily to see that the feedback has anything to do with with the pointing.
Over-sized local laser emergency switch was held by large C clamp at the south end. This was replaced by a smaller one and it is mounted with magnets.
The Innolight laser was turned off, while the interlock was wired.
The laser chiller temp is fluctuating and the power output is decreasing. See 120 days plot.
Yesterday I removed ~300cc water from the overflowing chiller tank.
Is the cooling line clogged? The chiller temp is 21C See 1 and 20 days plots
Last night we stopped the air conditioning. It made HDTEMP increase.
Later we restored them and the temperature slowly recovered. I don't know why the recovery was so slow.
Rough draft of updated interlock drawing by Ben is here.
I hooked up interlock to the Innolight 2W 1064 nm in the enclosure. The manual shutter is closed on this unit.
SAFETY GLASSES REQUIRED !
The 2W PSL laser is turned off. The danger laser lights are not illuminated at the entry doors because of malfunctioning electronic circuit!!!
Laser safety glasses are still required! Other lasers are in operation!
BEN fixed the interlock. The laser is turned ON. Thanks for all, Rich and Sam who came over to help. Atm1
All emergency shut- off switches, lights and door indicators are working at this moment. More about this tomorrow.
Atm2, PSL enclosure interlock jungle without REAL schematic drawing.....at this point.... We all agreed it is easier to redo the hole thing than find the problem
Atm3, Emergency shut off switches and illuminated signs from entry doors to AC on-off box ( Use this switches in emergency ONLY, otherwise leave alone , even it is labeled obsolete !)
Summery: I still do not really know what was wrong.
The janitor accidentally hit the laser emergency kill switch at room 103 entry door. It did shut down the PSL laser. The laser was turned back on.
As PSL-126MOPA_DTEC went up, the power out put went down yesterday
The NPRO cooling water was clogged at the needle valve. The heat sink temp was around ~37C
The flow-regulator needle valve position is locked with a nut and it is frozen. It is not adjustable. However Jeenne's tapping and pushing down on the plastic hardware cleared the way for the water flow.
We have to remember to replace this needle valve when the new NPRO will be swapped in. I checked on the heat sink temp this morning. It is ~18C
There is condensation on the south end of the NPRO body, I wish that the DTEC value would just a little higher like 0.5V
The wavelenght of the diode is temp dependent: 0.3 nm/C. The fine tuning of this diode is done by thermo-electric cooler ( TEC )
To keep the diode precisely tuned to the absorption of the laser gain material the diode temp is held constant using electronic feedback control.
This value is zero now.
The laser power is down 5-6%
I adjusted the steerings to the PMC and gained 7%. Now the MC_TRANS 7.0 has been recovered.
Actually I need another 7% to get MC_TRANS 7.5.
But I couldn't find how I can recover 126MOPA-AMPMON to 2.8ish.
[From Jenne: When we first opened up the MOPA box, the NPRO's cooling fins were HOT. This is a clear sign of something badbadbad. They should be COLD to the touch (cooler than room temp). After jiggling the needle valve, and hearing the water-rushing sounds, the NPRO radiator fins started getting cooler. After ~10min or so, they were once again cool to the touch. Good news. It was a little worrisome however that just after our needle-valve machinations, the DTEC was going down (good), but the HTEMP started to rise again (bad). It wasn't until after Alberto's tinkering that the HTEMP actually started to go down, and the power started to go up. This is probably a lot to do with the fact that these temperature things have a fairly long time constant.
Also, when we first went out to check on things, there was a lot more condensation on the water tubes/connections than I have seen before. On the outside of the MOPA box, at the metal connectors where the water pipes are connected to the box, there was actually a little puddle, ~1cm diameter, of water. Steve didn't seem concerned, and we dried it off. It's probably just more humid than usual today, but it might be something to check up on later.]
I have just removed an other 400 cc of water from the chiller. I have been doing this since the HTEMP started fluctuating.
The Neslab bath temp is 20.7C, control room temp 71F
Today I've attended the laser safety seminar.
Laser safety glasses cleaned in " Dawn Ultra " mild soap - water solution and measured for 1064 nm transmission at 150 mW
All safety glasses were cleaned in soapy water by Bob. I measured their transmission at 1064 nm, 150 mW, beam diameter 1.5 mm They are in working order, no transmission.
10 pieces of KG-5, fit over, from Laser Safety
4 pieces of KG-5, std size, from Drever Lab, best visibility
1 piece of KG-5 coated for visible, std size, from Kentek
15 pieces of green-plastic LOTG-YAG, fit over, from UVEX
7 pieces of green-plastic B-D+S 137, std areo fit, from Sperian
3 pieces of green-plastic, old Thorlab, fit over
2 pieces of green-plastic, fit over, from Laservision
8 pieces of braun- plastic, fit over, for green & IR protection, from UVEX & Thorlabs
The 2W Innilight shutdown shut when I opened side door for safety scan. This was not a repeatable by opening -closing side doors later on. Turned laser on, locked PMC and MC locked instantly. The MC was not locked this moring and it seemed that the MC2 spot was still some high order mode
like yesterday. MC lock was lost when the janitor bumped something around the MC.
We found that the laser had completely shut off for ~ 4 hours even with all the PSL doors closed.
We are guessing it is related to the interlock system and Steve is working on it to fix it.
This is a continuation of this
The low pass filter is finally acceptable, and its Bode graph is below (on a ~3Hz frequency span that shows the cutoff frequency is at 0.1Hz)
The 2W Innolight was off for 4 hours.
The laser went off around 11am yesterday. It was turned on
The DASWG lscsoft package repositories have a lot of useful analysis software. It is all maintained for Debian "sqeeze", but it's mostly installable without modification on Ubuntu 10.04 "lucid" (which is based on Debian squeeze). Basically the only thing that needs to access the lscsoft repositories is to add the following repository file:
controls@rossa:~ 0$ cat /etc/apt/sources.list.d/lscsoft.list
deb http://www.lsc-group.phys.uwm.edu/daswg/download/software/debian/ squeeze contrib
deb-src http://www.lsc-group.phys.uwm.edu/daswg/download/software/debian/ squeeze contrib
deb http://www.lsc-group.phys.uwm.edu/daswg/download/software/debian/ squeeze-proposed contrib
deb-src http://www.lsc-group.phys.uwm.edu/daswg/download/software/debian/ squeeze-proposed contrib
A simple "apt-get update" then makes all the lscsoft packages available.
lscsoft includes the nds2 client packages (nds2-client-lib) and pynds (python-pynds). Unfortunately the python-pynds debian squeeze package currently depends on libboost-python1.42, which is not available in Ubuntu lucid. Fortunately, pynds itself does not require the latest version and can use what's in lucid. I therefore rebuilt the pynds package on one of the control room machines:
$ apt-get install dpkg-dev devscripts debhelper # these are packages needed to build a debian/ubuntu package
$ apt-get source python-pynds # this downloads the source of the package, and prepares it for a package build
$ cd python-pynds-0.7
$ debuild -uc -us # this actually builds the package
$ ls -al ../python-pynds_0.7-lscsoft1+squeeze1_amd64.deb
-rw-r--r-- 1 controls controls 69210 2012-05-29 11:57 python-pynds_0.7-lscsoft1+squeeze1_amd64.deb
I then copied the package into a common place:
I then installed it on all the control room machines as such:
$ sudo apt-get install libboost-python1.40.0 nds2-client-lib python-numpy # these are the dependencies of python-pynds
$ sudo dpkg -i /ligo/apps/debs/python-pynds_0.7-lscsoft1+squeeze1_amd64.deb
I did this on all the control room machines.
It looks like the next version of pynds won't require us to jump through these extra hoops and should "just work".
Valera and I put the 2 Guralps and the Ranger onto the big granite slab and then put the new big yellow foam box on top of it.
There is a problem with the setup. I believe that the lead balls under the slab are not sitting right. We need to cut out the tile so the thing sits directly on some steel inserts.
You can see from the dataviewer trend that the horizontal directions got a lot noisier as soon as we put the things on the slab.
The tiles were cut out in 1.5" ID circle to insure that the 7/16" OD lead balls would not touch the tiles on Wednesday, May 26, 2010
Granite surface plate specifications: grade B, 18" x 24" x 3" , 139 lbs
These balls and granite plate were removed by Rana in entry log #3018 at 5-31-2010
I tried to calculate the frequency of resonance using Rayleigh's method. approximated the geometry of lead to be that of a perfect cylinder, and the deformation in the lead by the deflection in a cantilever under a shear strain.
this rough calculation gives an answer of 170Hz and depends on the dimensions of each lead, number of leads, and mass of the granite. But the flaw pointed out is that this calculation doesnot depend on the dimension of the granite slab, nor on the exact placing of the lead spheres with respect toteh COM of the slab.
I will put up the calculations details later, and also try to do a FEM analysis of the problem.
BTW, latex launched this new thing for writing pdfs. doesnot require any installations. check http://docs.latexlab.org
I guess we forgot to close V5, so we were indeed pumping on the ITMY and ETMY annuli, but the other three were isolated suggest a leak rate of ~200-300 mtorr/day, see Attachment #1 (consistent with my earlier post).
As for the main volume - according to CC1, the pressure saturates at ~250 uTorr and is stable, while the Pirani P1a reports ~100x that pressure. I guess the cold-cathode gauge is supposed to be more accurate at low pressures, but how well do we believe the calibration on either gauge? Either ways, based on last night's test (see Attachment #2), we can set an upper limit of 12 mtorr/day. This is 2-3x the number Steve said is normal, but perhaps this is down to the fact that the outgassing from the main volume is higher immediately after a vent and in-chamber work. It is also 5x lower rate of pressure increase than what was observed on Feb 2.
I am resuming the pumping down with the turbo-pumps, let's see how long we take to get down to the nominal operating pressure of 8e-6 torr, it ususally takes ~ 1 week. V1, VASV, VASE and VABS were opened at 1030am PST. Per Chub's request (see #14435), I ran RP1 and RP3 for ~30 seconds, he will check if the oil level has changed.
Let's leave things in this state overnight - V1 and V5 closed so that neither the main volume nor the annuli are being pumped, and get some baseline numbers for what the outgassing rate is.
I was lucky to notice that the nitrogen supply line to the vacuum valves was leaking. Closed ALL valves. Open supply line to atm. Fixed leak.
This was done fast so the pumps did not have to be shut down. Pressurized supply line and open valves to
"Vac Normal" condition in the right sequence.
The first real rain of this year finds only one leak at the 40m
Johannes found dripping water at the vac rack. It is safe. It is not catching anything. Actual precipitation was only 0.62"
Dan sealed the leak today.
We are leaving the PLL as it is locked in order to see the long term stability. And we will check the results in early morning of tomorrow.
DO NOT disturb our PLL !!
(what we did)
After Mott left, Matt and I started to put feedback signals to the temperature control of NPRO.
During doing some trials Matt found that NPRO temperature control input has an input resistance of 10kOhm.
Then we put a flat filter ( just a voltage divider made by a resistor of ~300kOhm and the input impedance ) with a gain of 0.03 for the temperature control to inject a relatively small signal, and we could get the lock with the pzt feedback and it.
In addition, to obtain more stable lock we then also tried to put an integration filter which can have more gain below 0.5Hz.
After some iterations we finally made a right filter which is shown in the attached picture and succeeded in obtaining stable lock.
Matt checked it in this morning and he found it's been locked during the night.
The MICH and PRCL motions have been measured in some different configurations.
According to the measurements :
+ PRCL is always noisier than MICH.
+ MICH motion becomes noisier when the configuration is Power-Recycled Michelson (PRMI).
The next actions are :
+ check the ASPD
+ check the demodulation phases
+ try different RFPDs to lock MICH
Tip-Tilts has almost no isolation up to 3Hz, and isolation of about 0.5 up to 10Hz.
They have vertical resonances at around 20Hz.
See Nicole's entry
For a comparison, the length fluctuation of Signal-Recycled ITMX (SRX) and ITMY (SRY) have been measured.
Roughly speaking the length motion of SRX and SRY are as loud as that of PRCL.
Some details about the measurement and data analysis can be found in the past elog entry (#5582).
In the process of converting the raw spectra to the calibrated displacements the SRM actuator was assumed to have a resonance at 1Hz with Q = 5.
(Notes on SRX/Y locking)
+ PRCL is always noisier than MICH.