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ID Date Author Type Categoryup Subject
  9019   Fri Aug 16 19:36:49 2013 CharlesUpdatePSLPMC_trans Channel

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.

  9094   Mon Sep 2 15:22:57 2013 JenneUpdatePSLPMC relocked

 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).

  9155   Tue Sep 24 10:55:45 2013 ranaUpdatePSLPMC re-aligned

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?

Attachment 1: psl-trend.png
psl-trend.png
  9252   Thu Oct 17 22:38:25 2013 MasayukiUpdatePSLPSL temperature changed

[Manasa, Masayuki]

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. 

ALS stability

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.

Attachment 1: in-loop.pdf
in-loop.pdf
  9255   Mon Oct 21 09:46:12 2013 SteveUpdatePSLLaser just turned on

I have just turned on the PSL Innolight laser. The laser shut down  with unknown reason a day ago.

Attachment 1: laserTurnedON.png
laserTurnedON.png
  9264   Wed Oct 23 15:46:01 2013 JenneUpdatePSLPMC was unlocked

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

  9291   Fri Oct 25 10:45:16 2013 SteveUpdatePSLlaser drift monitor set up

Quote:

Quote:

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.

Attachment 1: laserDriftMon.jpg
laserDriftMon.jpg
Attachment 2: PMCT_120d.png
PMCT_120d.png
Attachment 3: PMCT_1000d.png
PMCT_1000d.png
  9292   Fri Oct 25 19:56:58 2013 ranaUpdatePSLlaser drift monitor set up

 

 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.

Attachment 1: PMC-IRSISSS.png
PMC-IRSISSS.png
Attachment 2: PA250052.JPG
PA250052.JPG
Attachment 3: PA280044.JPG
PA280044.JPG
  9329   Fri Nov 1 19:09:01 2013 rana, evanConfigurationPSLPMC reflected beam nonsense

 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.

  9333   Mon Nov 4 09:03:21 2013 SteveUpdatePSLPMC auto locker

Quote:

 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

Attachment 1: 3dTREND.png
3dTREND.png
  9381   Thu Nov 14 00:33:37 2013 ranaConfigurationPSLPMC LO is dying...

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.

Attachment 1: Untitled.png
Untitled.png
  9397   Fri Nov 15 14:08:13 2013 manasaUpdatePSLPSL Innolight shuts down again

Quote:

I have just turned on the PSL Innolight laser. The laser shut down  with unknown reason a day ago.

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.

  9517   Fri Jan 3 15:19:39 2014 ranaSummaryPSLPSL pointing monitoring

 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??

Attachment 1: PSL_pointing_2013.png
PSL_pointing_2013.png
  9518   Fri Jan 3 18:21:45 2014 ranaSummaryPSLPSL pointing monitoring

 

 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.

  9519   Mon Jan 6 16:30:31 2014 JenneSummaryPSLPSL pointing monitoring

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]

MCspots_6Jan2014.png

  9542   Thu Jan 9 10:34:58 2014 SteveUpdatePSLPSL pointing changes in pitch

  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

Attachment 1: Lfnfdnc.png
Lfnfdnc.png
Attachment 2: 24hPSLpointing.png
24hPSLpointing.png
  9545   Fri Jan 10 10:28:03 2014 SteveUpdatePSLPSL pointing changes

 

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.

 

 

Attachment 1: clamped.png
clamped.png
  9547   Fri Jan 10 15:33:02 2014 SteveUpdatePSLlaser drift monitor set up idea

this locationQuote:

Quote:

Quote:

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

Attachment 1: 2daysDrift.png
2daysDrift.png
  9549   Mon Jan 13 11:08:48 2014 SteveUpdatePSL3 good days of IOO pointing

 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.

 

Attachment 1: 3gdPSLpointing.png
3gdPSLpointing.png
  9552   Tue Jan 14 10:12:12 2014 SteveUpdatePSLlaser drift monitor set up idea

Quote:

this locationQuote:

Quote:

Quote:

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.

Attachment 1: bad4thday.png
bad4thday.png
  9553   Tue Jan 14 10:34:57 2014 SteveUpdatePSLgreen transmission measurment

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

Attachment 1: greenPickUp.jpg
greenPickUp.jpg
  9814   Tue Apr 15 13:24:42 2014 SteveUpdatePSLlaser turned on

The 2W Innolight was off for 4 hours.

Attachment 1: laserOff4hrs.png
laserOff4hrs.png
Attachment 2: laserShutsDown.png
laserShutsDown.png
  9895   Thu May 1 17:14:36 2014 steveUpdatePSLthin window AR measured

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.

  9902   Fri May 2 10:38:29 2014 steveUpdatePSLthin window AR measured

Quote:

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?

 

 

  9944   Tue May 13 00:46:58 2014 ranaHowToPSLPMC relocking

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.

  9960   Fri May 16 00:25:53 2014 ranaUpdatePSLPMC realign

 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.

  9961   Fri May 16 09:46:05 2014 SteveUpdatePSLpointing monitoring

Quote:

 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.

  9986   Wed May 21 22:15:37 2014 ericqUpdatePSLPMC relocked

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.

  9993   Mon May 26 20:10:14 2014 ericqUpdatePSLPMC relocked

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

  9997   Tue May 27 22:29:17 2014 JenneUpdatePSLPSL making noises

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.

  9998   Wed May 28 11:55:16 2014 SteveUpdatePSLPSL Innolight controller fan is noisy

Quote:

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

Attachment 1: 2WinnoRFan.jpg
2WinnoRFan.jpg
  10030   Thu Jun 12 10:41:58 2014 SteveUpdatePSLPMC-T trend of 4 years

Quote:

Quote:

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.

Attachment 1: 4yTrend2Winno.png
4yTrend2Winno.png
  10072   Thu Jun 19 14:41:00 2014 ManasaUpdatePSLISS disabled

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.

  10076   Thu Jun 19 17:28:19 2014 SteveUpdatePSL window device is ready for test

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

Attachment 1: softW2.jpg
softW2.jpg
Attachment 2: softW2b.jpg
softW2b.jpg
  10091   Tue Jun 24 13:02:54 2014 ManasaUpdatePSLRingdown PD installed

Quote:

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.

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.

Attachment 1: PSL_ringdown.png
PSL_ringdown.png
  10115   Mon Jun 30 22:40:21 2014 ManasaUpdatePSLAOM ringdown

Quote:

Quote:

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.

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). 

Attachment 1: AOM_ringSample1.pdf
AOM_ringSample1.pdf
  10140   Mon Jul 7 16:39:09 2014 manasaUpdatePSLPMC ringdown setup

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 

Attachment 1: PMC_ring.png
PMC_ring.png
  10146   Mon Jul 7 21:36:33 2014 Jenne, ranaUpdatePSLPMC local oscillator is going wonky

The PMC local oscillator is going a little weird dyingWe need to check out why the level is fluctuating so much.

Here's a 6 month plot, where you can see that the lower level keeps getting lower (y-axis is dBm):

PMC_LO_failing.pdf

This LHO entry from 2008 shows where we first discovered this effect. As Rick Savage and Paul Schwinberg later found out, the ERA-5SM+ amplifier slowly degrades over several years and was replaced for both of the eLIGO interferometers. We have spares in the Blue box and can replace this sometime during the day.

Our PMC LO is made by this obsolete crystal oscillator circuit: D000419. There are many versions of this floating around, but they all have the ERA-5 issue.

  10148   Mon Jul 7 22:18:26 2014 KojiUpdatePSLPMC local oscillator is going wonky

It seems that there is no better chip in MiniCircuits line-up with the same form factor.
ERA-5 is the most powerful one in the ERA (or MAR) series.

If the output is ~0dBm we have MAR-6SM in stock. But I suspect that ERA-5 was driven at the power level close to its saturation (~18dBm).

If we allow different form factors, we have GVA-** or GALI-** in the market and also in the blue tower, in order to gain more performance margin.
If it is difficult to apply them, I would rather use another ERA-5 with enhanced heat radiation.

I'm sure that Downs has EAR-5 replacement.

  10149   Mon Jul 7 23:19:55 2014 ranaUpdatePSLPMC ringdown setup

Quote:

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. 

 I am guessing that 75 mW will burn / destroy any Thorlabs PD. I hope that mW is supposed to be uW.

  10153   Tue Jul 8 15:28:32 2014 KojiUpdatePSLPMC local oscillator is going wonky

Koushik and Koji try to fix the PMC oscillator issue. So we remove the module from the rack.
This means we don't have the PMC transmission during the work.

  10159   Wed Jul 9 00:47:22 2014 KojiUpdatePSLPMC local oscillator is going wonky

Koushik replaced an ERA-5 in the PC path. We put the module back to the rack and found no change.
The epics LO level monitor monitor is still fluctuating from 6~11dBm. We need more thorough investigation
by tracing the signals everywhere on the board.

Despite the poor situation of the modulation, PMC was locking (~9PM). Rana suspect that the PMC demodulation
phase was not correctly adjusted long time. 

Koushik has the measured power levels and the photos of the board. I'll ask him to report on them.

  10160   Wed Jul 9 00:59:09 2014 ranaUpdatePSLPMC local oscillator is going wonky

Quote:

Koushik and Koji try to fix the PMC oscillator issue. So we remove the module from the rack.
This means we don't have the PMC transmission during the work.

 After the ERA-5 was replaced (see Koushik elog) we relocked the PMC.

The new LO level going into the PMC servo card is +11.5 dBm. The LO mon on the PMC card reads 9 dBm and seems so flat I now suspect the monitor circuit.

I also measured the RF drive to the EOM as a function of C1:PSL-PMC_RFADJ on the Phase Shifter screen.

The phase shifter slider gives ~75 deg/V in phase shift of the RF out to the EOM. I tried to optimize the loop gain quickly using the fluctuations in the reflected power. The loop oscillates at high frequency with the slider at 21 dB and also at 9 dB. So I set the gain at +14 dB. Needs to be optimized correctly in the daytime.

 

Attachment 1: PMC_RFslider.pdf
PMC_RFslider.pdf
  10162   Wed Jul 9 11:41:12 2014 KoushikUpdatePSLPMC local oscillator is going wonky

Quote:

Koushik replaced an ERA-5 in the PC path. We put the module back to the rack and found no change.
The epics LO level monitor monitor is still fluctuating from 6~11dBm. We need more thorough investigation
by tracing the signals everywhere on the board.

Despite the poor situation of the modulation, PMC was locking (~9PM). Rana suspect that the PMC demodulation
phase was not correctly adjusted long time. 

Koushik has the measured power levels and the photos of the board. I'll ask him to report on them.

 Updates from Koushik:

The power levels measured (before and after relacement of ERA-5) are as follows:

LO to Servo : Vout = 2.3 Vpp / Pout = 11.21 dBm at f = 35.5 MHz

RF to PC   :   Vout = 354 mVpp / Pout = -5.1 dBm at f= 35.5 MHz

The measurements were done using an oscilloscope with 50 ohms load impedance. Unfortunately the photos are not available from the camera.

  10164   Wed Jul 9 16:33:05 2014 manasaUpdatePSLPMC ringdown setup

Quote:

Quote:

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. 

 I am guessing that 75 mW will burn / destroy any Thorlabs PD. I hope that mW is supposed to be uW.

 It was ~7.5mW and measured ~2V at the PD output (given its range 0-5V ) on the oscilloscope . So PD is safe !

  10167   Wed Jul 9 19:53:34 2014 ranaUpdatePSLPMC LO monitor trend (5 years)

LODET.png

The first step is

The second uptick (In Nov 14, 2013) is when I removed a 3 dB attenuator from the LO line. Don't know why the decay accelerates after that.

  10172   Thu Jul 10 01:02:13 2014 ranaUpdatePSLmore PMC science

Increased gain and SNR in PMC LO monitor circuit.

  1. R20: 499 -> 50k Ohms (increases gain by 100)
  2. Used Marconi to drive the LO input and readout C1:PSL-PMC_LODET
  3. Fit this function and loaded it into the psl.db file. The old Kalmus way used LOGE, but I wanted to use log10, so I did. The sensor is only useful in a narrow band. Since the signal is so low at low levels, I just fit to the highest 4 points because I was too lazy to do proper weighting. Do as I say, not as I do.

Plot with data and fit attached.

** N.B.: in order to update the calibration without rebooting, I used the following command: z write C1:PSL-PMC_LOCALC.CALC "2.235*LOG(B)+12.265". This allows us to update EPICS CALC records without rebooting the IOC.

Attachment 1: PMCloCal.pdf
PMCloCal.pdf
  10173   Thu Jul 10 02:09:20 2014 JenneUpdatePSLFSS Fast gain set

I have put in a new nominal value for the FSS fast gain:  21.5 dB. 

There is an oscillation peak in the MC error point spectra around 41.5 kHz if the FSS gain is set too high.  I used the 4395 to have a look at the MC error point, and saw that if I set the FSS fast gain any lower than about 18 dB, the peak wasn't getting any smaller than -41 dBm.  If I set the fast gain any higher than about 26 dB the peak wouldn't get any larger than about -34 dBm. 

However, if I set the gain to 19.5dB, the PC RMS drive is consistently above 2 V, which isn't so good.  If I crank the gain up to 27 dB or more, the PC RMS will stay below 0.9 V, which is great. 

As a compromise, I have decided on 21.5 dB as the new FSS fast gain.  This puts the oscillation peak at about -39.5 dBm, and the PC RMS around 1.6 V.

I changed the nominal gain by ezcawrite C1:PSL-STAT_FSS_NOM_F_GAIN 21.5.  This sets the nominal value so that the FSS screen's fast slider doesn't turn red at the new value.  And, since the MC autolocker reads this epics channel and puts that into the gain during the mcup script, the MC autolocker now uses this new gain.  For reference, it used to be set to 23.5 dB.

  10203   Tue Jul 15 17:34:01 2014 manasaUpdatePSLproposing AOM re-alignment

I am going to tweak the alignment of the beam into the AOM (before the PMC) tomorrow morning. If anybody has any objections to this, please raise a red flag.

Proposed alignment procedure:

1. Reduce PSL power to say 10% 

2.  Since the AOM is not on any sort of a mechanical stage, I will have to just play around carefully until I see a maximum power rejection into first order.

I am assuming that moving the AOM is not going to affect the input pointing because all these activities are happening before the PMC. So as long as I have the output beam from the AOM aligned to the PMC at the end, everyone should be happy.

  10216   Wed Jul 16 15:26:48 2014 SteveUpdatePSLPSL Innolight controller fan is dying

Quote:

Quote:

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 fan is dying. It is changing speed erratically and stops for short time periods. It is very likely to stop rotating soon. It will halt all operations in the lab. We can not see the PMC-T power because Manasa is working on

 AOM alignment.

 

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