1. Filter module (FM1) on PRCL and MICH show significant delay while enabling and disabling.
2. I tried to fix PMC alignment (PMC trans was 0.76). I was not able to get PMC trans more than 0.79.
PMC has been this way since yesterday.
3. MICH is still bright when locked (ASDC_OUT reads 0.08 for dark and 2.0 for bright). We suspect it is because of the AS55_I error offset that persists even after running LSCoffsets script.
4. PRMI shows some dither at 3Hz when locked.
PMC is fixed with 0.84 in transmission. It was misaligned in pitch (fixing this increased PMC_trans to 0.822 from 0.773) and Koji also touched the wave plate and polarizer (changed PMC_trans to 0.845).
Last night I measured the modulation depth of the MC incident beam.
The beam is taken from one of the PO beam at the wedge plate before the IMC.
After removing the knife edge to dump this beam, the beam is sent to the west side
of the PSL table and put into the OSA cavity.
[The beam dump was returned after the measurement.]
I had some confusion and after all I use the OSA labeled as AS OSA rather than the one on the PSL table.
[The AS OSA was returned to the AP table.]
The transmission was detected by PDA255 and filtered by ITHACO 1201 preamp with G=10, no HPF, 30kHz LPF.
It was confirmed that the peak amplitudes are not reduced by the LPF filter. The resulting time series
was recorded by an oscilloscope.
Three measurements have been taken. The 11MHz peaks are offset by the carrier peak. They appropriately
removed. The ratio of the sideband and carrier peaks is converted to the modulation depth using the following formula.
P_sb / P_ca = [J1(m)/J0(m)]^2
The modulation depth for the 11MHz: 0.190 +/- 0.003
The modulation depth for the 55MHz: 0.2564 +/- 0.0003
The three scans showed very similar numbers. That's why the statistical error is such small.
I don't think the systematic error is not such good.
This number is much different form the previous meaurement by Mirko.
http://nodus.ligo.caltech.edu:8080/40m/5519 m=0.14 (11MHz) & 0.17 (55MHz)
but the measured voltages and the modulatio depths are inconsistent.
http://nodus.ligo.caltech.edu:8080/40m/5462 m=0.17 (11MHz) & 0.19 (55MHz)
Probably the modulation depths should be checked by the IMC again.
However, it is certain that the 55MHz modulation exists, and even larger than the 11MHz one.
The next is to confirm that the modulation frequency is matched with the IMC FSR.
It is to make sure that the modulation is transmitted to the main IFO without attenuation.
The PMC locked manually. MC grabbed lock instantaniously
Note: The TRY PD isn't installed and normalized properly yet, so the IFO OVERVIEW screen indicates lock for the Yarm constantly, which is not true. Hopefully in the next day or so the screen will be back to telling the truth.
Also, the LSC Locking was left ENABLED (presumably over the weekend). This is not so good. It can kick optics around, so we should all take a look when we walk through the control room, and if no one is locking, please disable the LSC master switch.
The MC seemed to be losing lock recently quite a bit. I noticed that the PC Drive RMS signal was red.
This means that the high frequency drive to the Pockels cell was too high by a factor of 2-3 and sometimes saturating and breaking the lock.
I fiddled with the gains on the FSS screen until this value went down. It looks like there is some kind of high Q oscillation; it takes a couple minutes for the PC Drive RMS to settle to its new position after changing the gains.
The attached trend plot show the last 2 hours. The mean is now back to ~1 V and seems OK. We should really examine the FSS or MC error point spectra with the RF analyzer while exploring this gain space.
Today Rana pointed out that our FSS slow servo is malfunctioning. It has been for a while that our laser temperature control voltage drifted from 0 to 10.
I looked at FSSSlowServo script that runs at op340m and controls the servo. Script disables the servo when MC transmission is less then FSS_LOCKEDLEVEL. But his value was set to 0.2 probably till reference cavity time.
This means that slow servo was not disabled when MC was unlocked. I changed this value to 7000.
Also I increased integral gain from 0.0350 to 0.215 such that fast control is always in the range 4.5 - 5.5
PMC aligned. C1:PSL-PMC-PMCTRANSPD improved from 0.72ish to 0.835ish.
I'm just now realizing that the PMC has also not been locked since noon today, and doesn't seem to be responding to anything right now.
wtf is going on here?
Rana showed up and diagnosed the problem as a railed FSS SLOW output. The SLOW Monitor about was showing ~6V, which is apparently a bad mode-hoppy place for the NPRO. Reducing the SLOW output brought things back into a good range which allowed the PMC to lock again.
In attempting to diagnose the problem I noticed that there is -100 mV DC coming out of the PMC RFPD RF output. This is not good, probably indicating a problem, and was what I thought was the PMC lock issue for a while. Need to look at the PMC RFPD RF output.
All of these changes were committed to the SVN.
To allow Annalisa to work on the Y-green alignment as I work with the X-green, the part of the PSL green beam that goes to the Y-green beat PD has been blocked with an iris.
Rana and I connected the PMC_trans output to the BNC connector board on the west end of the PSL table (the channel is labeled). I took a few spectra off of PMC_trans and the SR785 was connected directly to the PMC_trans output for about an hour.
Data will follow.
The PMC was locked on an LG 10 mode (or something like it), for at least the last 8 hours. I relocked it on the regular 00 mode, and it's fine now.
Also, in CDS news, I did an mxstream restart (the RCG upgrade is supposed to make this not an issue anymore...), and did a "diag reset" afterwards, and all of the IPC errors except for one in the LSC model have gone away (OAF is still not running....on my to-do list, but not super high priority).
After relocking the PMC at a good voltage, Steve and I re-aligned the beam into the PMC by walking the last two steering mirrors. After maximizing the power, we also aligned the reflected beam by maximizing the PMC_REFL_DC with the unlocked beam.
Transmission is back to 0.84 V. We need Valera mode matching maintenance to get higher I guess. Maybe we can get a little toaster to keep the PMC PZT more in the middle of its range?
PSL temperature changed
The beat note of Xarm looked somehow strange before (elog). It should be the highest when the green transmission power is highest, in other words when the end green PDH locks with a TEM00 mode. But it was not like that. When the end PDH locked with other modes (GTRX: below 0.3), the beat note was higher than TEM00 mode (GTRX: around 0.5).
We guessed that end green laser was somewhere around the point where there were 2 stable TEM00 modes . In order to move away from this unstable region of the end laser, we changed PSL temperature to obtain beat note at a different green laser frequency where we do not have any of the weird modes oscillating.
We changed the PSL temperature from 31.63 degree to 31.33 degree. We measured the in-loop noise of ALS loop and I attached it. There is not big difference in Yarm, but the Xarm in-loop noise become better in high frequency region. We think before the xend green laser was in a not-so-good state and the laser had more frequency noise then.
After change PSL temperature, Xarm ALS is so stable. Actually Xarm is being locked right now and it is locked for more than 50 minutes!!
Although the Xarm ALS is so stable, Yarm ALS is not stable right now. It lost lock by ~5min. We don't know what is the reason, so we will try to fix it tomorrow.
I have just turned on the PSL Innolight laser. The laser shut down with unknown reason a day ago.
The PMC was unlocked for a little over an hour. I relocked it, and the MC locked itself. Today, it looks like PMC yaw alignment is bad, and maybe pitch isn't so good either. Transmission is 0.77
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.
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.
While looking at the PMC REFL beam for the AOM diffracted beam, we noticed that although only one beam exists between the PMC and the first steering mirror, there are two afterwards and they both go to the PMC REFL RFPD!!! This is madness. We only want one beam on our PDH diode.
The reason that we have two beams is that that first steering mirrors is actually a (W1-PW-1025-UV-1064-45P) non-wedged window with an AR coating on only one side. So two beams come out of it. There is a terrible and floppy and illegal anodized aluminum dump close to this beam which *someone* probably intended to use as a "scraper" to get rid of one of the beams.
Black anodized aluminum is a horrible beam dump material at 1064 - its about as grey as Steve's chair. And its so soft that it scatters light back into the PMC and makes more acoustic noise. And it is mounted so poorly (only one screw) that it can easily be bumped and twist and miss the beam. Punchline: only use anodized aluminum dumps for stray light around cameras or for HeNe for OL. Its NOT allowed anywhere where we care about interferometry of NIR beams.
It was also set to dump the dimmer beam. On Monday, we should order ~5 W1 and get them with a wedge of 1-2 deg. Then we use a black glass dump for the dim beam and orient the bright one to hit the REFL camera and the PMC REFL PD.
For the weekend, I have adjusted the crappy grey aluminum flapper to catch the bright beam so that the PMC REFL image no longer shows the interference fringe of two beams. Lets see how the PMC drifts over the next 3 days.
I was working on the electronics bench and what sounded like a huge truck rolled by outside. I didn't notice anything until now, but It looks like something became misaligned when the truck passed by (~6:45-6:50 pm). I can hear a lot of noise coming out of the control room speakers and pretty much all of the IOO plots on the wall have sharp discontinuities.
I haven't been moving around much for the past 2 hours so I don't think it was me, but I thought it was worth noting.
The PMC auto locker is not set to acquire error message made me lock PMC manually. Arms locked instantly: TRY 0.9 V and TRX 0.65 V
Back in 2009, Jenne replaced the PMC board mixer with a Level 13 one. Today I noticed that the LO level on the PMC screen was showing a LO level of ~5-10 dBm and fluctuating a lot. I think that it is related to the well known failure of the Mini-Circuits ERA-5SM amplifier which is on the D000419-A schematic (PMC Frequency Reference Card). The Hanford one was dying for 12 years and we found it in late 2008. If we don't have any in the blue bin, we should ask Steve to order 10 of them.
The attached trend shows 2000 days of hour trend of the PMC LODET channel. The big break in 2009 is when Jenne changed the mixer and then attenuated the input by 3 dB. The slow decay since then is the dying amplifier I guess.
Since the LOCALC channel was not in the trend, I added it to the C0EDCU file tonight and restarted the FB DAQD process. Its now in the dataviewer list.
I went out and took out the 3 dB attenuator between the LO card and the PMC Mixer. The LO monitor now reads 14.9 dBm (??!!). The SRA-3MH mixer data sheet claims that the mixer works fine with an LO between 10 and 16 dBm, so I'll leave it as is. After we get the ERA-5, lets fix the LODET monitor by upping its gain and recalibrating the channel.
PSL NPRO shut down again today for reasons unknown. I was working near the IOO rack and noticed there was no light at both the refl and trans PMC cameras. Jenne and I checked the PSL and found the 'OFF' red switch on the laser driver lit up. Switching ON the green button brought the laser back. PMC and MC autolocked after this.
This is a 10-minute trend of the last 60 days of the pointing of the PSL beam.
The main fluctuation seems to be at the ~30 day time scale (not 24 hour) and its all in the vertical direction; the horizontal drift is ~10x less (as long as we believe there is no calibration error).
So what's causing all of this vertical shift? And why is there not just as much horizontal??
I went to the PSL table to re-align the input pointing to the IMC. After trying to optimize the pointing into the PMC and not succeeding I also then touched the wrong mirror and messed up our IOO QPD reference pointing.
The IMC is locking again, but I'll have to fix the pointing on Monday.
I'm not sure which pointing Rana wanted to fix today, but here's a measurement of the MC spots. They actually look pretty good. There is some room for improvement, but not a lot, so I'm leaving it alone for now, while I play with other things in the IFO.
spot positions in mm (MC1,2,3 pit MC1,2,3 yaw):
[0.63368182839757914, 1.3004245778952557, 0.33621668795755993, -1.5585578137597658, -3.1344594013487286, -1.0533063060089816]
IOO QPDs tested in dark, lighted and open PSL enclosure. The created temperature change 0.03 C has effect on monitoring in pitch.
Atm1, all lights off 10 min, PSL enclosure lights on 10 min, all lights off 15 min, open door # 11 at north east corner of enclosure ( HEPA filters are running at 30V ) for 10 min, closed-dark enclosure 15 min
dark 10, lighted 10, dark 15, open-dark 10 and closed-dark 15 minutes
Atm2, Pitch drift of 24 hours does not recover
I looked at IOO QPDs again. QPD_POS was clamped by one screw. Dog clamp was added on the unclamped side.
QPD_ANG chassis has no isolation to optical table..._POS has. QPD_ANG base was tightened also.
Both QPDs moved a little bit but I did not centered them. The spot sizes are 2-3 mm They should be smaller.
How ever, we still can not explane the pitch movement of the IOO beam
Razor beam dumps were labeled at the AP table.
The 40m roof was cleaned from leafs this morning.
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
Three good days of IOO pointing: Friday, Sat and Sun What was changed? May be the clamping on Friday?
IOO vertical changes recovering as tempeture. IP is clipping at plastic enclosure of ETMY
NOTE: ANTS at the PSL optical table. I will mop with chemicals tomorrow if we see more.
I do like to move IOO-QPD_POS temporarily to see that the feedback has anything to do with with the pointing.
GariLyn is using our green light on the west side of the PSL table. The green PDA36As were moved and the HEPA turned up to 60V
The 2W Innolight was off for 4 hours.
CVI broadband AR coating was measured at the PSL-enclosure table around 9-10am today. The 2W Innolight first PBS S polarization beam was used with an other 1/2 wave plate and PBS.
W2-PW1-1004-C-633-1064-0 This 0.045" thick window has 0.7- 0.8 % reflected beam on each sides at 5 degrees of incidence, P polarization.
The specification is R avg <0.5 % per surface at 0 degree
Rana wants The device would be useless with such a high R, but R 0.1% is OK so I will get V coating.
CVI V-AR coating at 1064 nm, 0 degree, catalog item is R< 0.25% on each sides,
R <0.1 % is custom at much higher prices.
This custom order should go with other orders that has similar need.
From CVI: 5-6-2014
I checked the trace info on the W2-PW1-1004-C-633-1064-0, BBAR coated window that you received. It is side 1, 0.42%R & side 2, 0.53%R @ 1064nm. And with the shift, I’m not too surprised you ended up with 0.7%. A V coat would start with <0.25% (and more typically coming in at ~0.1%) per surface. As far as stock options, I have a 1”dia x 4mmT, fused silica window that is recorded as side 1, R=0.09 and Side 2, R=0.08% @ 1064. Is this too think or will it work for you?
The PMC runs out of range sometimes due to the daily temperature swing. The voltage swings up after sunset and then starts to swing down before sunrise. So when you relock the PMC at the beginning of the locking night, the mnemonic from the PMC is:
Sun Go Low, Lock Me Voltage Low.
Tonight I noticed that the drop in PMC transmission was ~1V, more than the usual of ~0.5V from the daily drift.
While re-aligning on the table, I noticed that the misalignment was not from either of the steering mirrors; i.e. I has to walk them both to get the alignment back. This implies that the misalignment is generated far upstream. Maybe the the laser itself is moving. We need some updates from Steve's laser misalignment tracker.
I'd like to replace the paper target with IOO -QPD_POS so we can log it.
PMC has been unlocked for ~4hrs, not sure why. It's servo gain was down at -10dB...
Relocked with transmission of .76V, MC locks fine with WFS, transmission of 15.5k.
I came in and PMC transmission was at 0.5V, and ETMX was swinging around a lot, (LSC mode was on).
Turning off oplevs let ETMX calm down. I realigned the PMC to 0.82V.
MC wouldn't relock, it looked misaligned in pitch and yaw on MC camera.
I've touched the alignment, and gotten the reflection below 0.5, but it unlocks periodically, spot positions aren't great, and turning on WFS throws it out of alignment. ughhhhh
Also, while I was working on the PSL table, I heard noise that sounded like a bearing rolling around. I suspected the HEPAs, since the one on the north east corner of the table has a problem when it's turned up high (we've known about this for a long time), however turning off the HEPAs didn't affect the noise. The noise is strongest near the back of the PSL controller on the shelf above the table, and the PSL controller box is vibrating. So, I suspect that the fan on the PSL controller box is about to give out.
EDIT: To clarify, I mean the Innolight's controller.
The bearing is chirping in the back of the 2W Innolight laser controller. It is loud enough to hear it. I placed 4 soft rubber feet under the controller to avoid shaking other things on self.
The HEPA filter bearing becomes noisy at 50V
Keep it at 20V for low noise
The aging of the laser came up when the noisy bearing showed. ~10% down in in 4 years. That is pretty good.
I would like to measure the switching time of the AOM. So I have disconnected the modulation input to the AOM that comes from the ISS. I have also turned OFF the SR560's and the AWG that belong to ISS.
Pics and cable connections of the state in which the ISS setup was left at, will be updated soon.
The window is at the north west corner of the PSL enclosure.
The 1 mm thick BK7 window is AR coated both side R <0.08%, W2-PW1-1004-1064-0
The PZT stack is 0.75" OD, 0.25" thick with ~ 6 mm ID, motion range 2.5 micron at 200V
Soft silicon rubber isolation.
RXA: This is the opto-mechanical phase shifter that Steve has built for diagnosing scattered light problems. We put it into the reflected light path of any of the cavities and see if it can move the scattering noise from DC up to a higher frequency. e.g.:
The paper on this from GEO
I installed a fast PDA10CF along the path of a leaking beam from one of the steering mirrors that direct the main beam to the PMC. This beam was dumped to a razor blade. I removed the razor blade and installed a Y1 to steer this beam through a lens on the PD.
Pics of the layout post-installation will be updated.
Also, I tested the AOM by giving it 0-1V modulation input from the AWG. This has been disconnected after the test. So everything should be as it was pre-testing.
Edit/manasa/ Data has not been fit correctly in here. A proper fit will follow this elog.
Proper fits and numbers are here :elog
Earlier last week I had tried to measure the AOM ringdown and concluded I could not make one.
I was proved wrong and I was able to make a measurement. I am still not sure why I was not able to make the measurement earlier with the very same settings and configuration.
What I did:
I gave the AOM a 0-1V modulation input using the signal generator (50 ohm feedthrough bnc was used to impedance match the AOM driver's modulation input). For the measurement here I used a 1Hz square wave. I used a 300MHz oscilloscope to look at the falling edge of the ringdown PD output installed.
I recorded a few ringdown samples. To get a quick number, I fit one such sample to find the AOM switching time as 1.48us (Plot attached).
I moved stuff on the PSL table to accommodate the PMC ringdown setup.
I used the beam that leaks from the steering mirror at the PMC transmission that was dumped to a razor blade dump. I installed a Y1 to steer the beam to the ringdown PD. Power in the beam 75mW.
Results are in here elog