40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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New entries since:Wed Dec 31 16:00:00 1969
ID Date Author Type Categoryup Subject
  681   Thu Mar 18 15:59:46 2010 FrankLaserstuff happensAmplifier service

We tried to adjust the pump light in xtal 1, since it seems to be a little too high - no success, so we aligned it (and the mirror set in front of the amplifier) back.

Note: The original pump current for the diodes was 48 A (so, we set it to this value).

The original temperatures of the pump diodes were:

D1: 20 degC

D2: 20 degC (was: 23.8, so we set it back, since then the output power slightly increased)

D3: 24 degC

D4: 25 degC

The observed output power downstream the PBSs (3) and waveplates (3 HWP + 1 QWP) was 29.5 W.

  751   Thu May 6 19:45:10 2010 DmassLaserstuff happensChalkboard
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  788   Wed May 26 17:13:07 2010 AidanLab Infrastructurestuff happensMoved a New Focus 9071 4-axis stage to 40m for doubling
  805   Tue Jun 8 10:35:16 2010 AidanMiscstuff happensMoved some equipment to 40m

I've taken the following items to the 40m.

  1. 40MHz AOM
  2. Thorlabs Broadband EOM
  3. 2x New Focus 9071 4-axis stages
  4. ZHL-1A RF amplifier
  5. ZHL-2A RF amplifier

They're all marked "Adhikari Lab".

  970   Tue Aug 24 02:38:42 2010 ZachLaserstuff happensThorLabs power meter head appears damaged

 While I was using the ThorLabs power meter today, I noticed that the slide-out filter appears to have a small bump on it near the center. I don't think I dinged it on anything, and it doesn't even really look like the result of a ding. It's tough to tell from the picture, but the bump is raised up, and not dented in. Has anyone seen this before (on our unit or elsewhere)?

PM_head_damage.jpg

  971   Tue Aug 24 03:00:20 2010 DmassLaserstuff happensThorLabs power meter head appears damaged

Someone burned it.

  999   Sun Aug 29 23:04:17 2010 ranaLab Infrastructurestuff happenslab cleanup

The lab has turned into a pit again. Please clean up your stuff. There cannot be tools lying around or drinks or water bottles or used booties or scraps of paper.

Empty the trashes, change the sticky mats, etc.

I also power cycled the router. This router was just a bad choice - I suggest we just get the 24-port router which the 40m is using. I'll ask Joe if it will work.

  1027   Thu Sep 9 00:22:14 2010 DmassElectronicsstuff happensNewport 3040 fukt?

I spent the better half of the day trying to debug the 3040 - I returned to an old working hardware setup with some extra 100 Ohm platinum RTDs, but I couldn't get one of the 3040's to read it in the right way. Resistance is "err", and nothing I seem to do or plug in seems to change it.

  • I checked the cabling to the 3040 - it was fine (no open connections, or mysterious shorts)
  • I checked the software limits and tried to make them as large as possible
  • I checked the sensor type and its coefficients
  • I switched the RTDs between 3040's, the failure followed the 3040
  • I did the onboard calibration for the RTD with a 100 Ohm thin film, as per the manuals instructions
  • I calibrated out the RTDs leads with a short, as per the manuals instructions.
  • I restored the machine to an earlier state (presumably from when it was still @ MIT), and repeated the above - still nothing.

Back story which may or may not be pertinent (guesses at possible damage here).

  • I snapped off the lead from my 100 Ohm RTD on my oven a few days ago.
  • I tried to use a 1000 kOhm RTD which I already had affixed to the oven as a spare, but the 3040 doesn't seem to know about these -
  • I had a 1 kOhm RTD in with the coefficients from a 100 Ohm for a bit (as it wouldn't let me switch them)
  • It seems unlikely that the having wrong sensor type could damage your 3040, as you have to cycle through types with the ipod-esque wheel to select the right one.

I then tried to use an NTC thermistor as the sensor, since I had some already wired up.

  • The manual quoted +/- ranges for the Steinhart-Hart coefficients for thermistors, which seems to imply that NTC and PTC are O.K to use
  • I pulled the NTC Steinhart-Hart coefficients from a quick matlab fit
  • When I tried to use them,the 3040 told me they were illegal and forced the coefficients back to their default positive values

I abandoned this and soldered some connectors on some spare 100 Ohm RTDs, of the exact same type which is working on the other 3040. I then experienced the problems from the first list...

I hope there is something stupid that I am somehow missing, otherwise I either have to skip the last couple measurements for the paper, or wait wait wait for a replacement / refurb / homestyle debugging of the 3040 - I will try to recruit a fresh set of eyes tomorrow to look at this.

  1028   Thu Sep 9 05:17:19 2010 DmassElectronicsstuff happensWho cares!

I switched to using one newport to control both ovens (one has no sensor, is just getting the actuation signal from teh other).

I was able to get the Mach Zehnder back and running.

Leaving it running overnight with with its calibration line on and HEPA off...I also have AC coupled thermistors on each oven being recorded by the DAQ now, so this should tell me exactly how "not ok" it is to use one controller for two ovens, which comes down to how correlated the low frequency temperature changes are inside the box.

Next up - HEPA on / off test, and comparison of 1 controller phase noise spectrum with 2 controller phase noise spectrum.

  1033   Thu Sep 9 18:31:48 2010 DmassElectronicsstuff happensWho cares!

I switched both HEPAs on to "low" and relocked the PMC at 6:40 PM today.

8:07 PM - both HEPAs turned to "med"

NTC Thermistor SR560 Gain set to 10 (was overloading @ 20).

NTC Thermistor mode set to "A-B" on one of the 560s with nothing hooked into B. Unknown if this makes it fluctuate or not. Channel is "daq1-gen4"

  1035   Thu Sep 9 21:12:50 2010 DmassElectronicsstuff happensRouter Crashed again?

Router crashed? Can't get channel list.

- Had Tara restart router, still can't get channel list. Was fine this afternoon.

  1036   Thu Sep 9 21:45:26 2010 DmassElectronicsstuff happensRouter Crashed again?

Quote:

Router crashed? Can't get channel list.

- Had Tara restart router, still can't get channel list. Was fine this afternoon.

 nds and daqd both seem to be running on fb0.

  1037   Thu Sep 9 21:56:29 2010 DmassElectronicsstuff happensCan't get data from 40m network?

Get_data worked without hitch when I used a vpn caltech connection. I think I am on the 40m ligo network (131.215...). I toggled on and off a couple times to check, and it only worked with the VPN on.

  1038   Thu Sep 9 21:57:37 2010 FrankElectronicsstuff happensRouter Crashed again?

looks like you have to work in the lab instead of sitting on the couch 
It's working if you try to get data from there... Or try to tunnel port 8088 through ssh, that should work too. That's the way i usually forward any services which are not accessible from outside.

Time to replace the router....

Quote:

Quote:

Router crashed? Can't get channel list.

- Had Tara restart router, still can't get channel list. Was fine this afternoon.

 nds and daqd both seem to be running on fb0.

  1039   Thu Sep 9 22:38:06 2010 ZachElectronicsstuff happensRouter Crashed again?

I noticed yesterday that although mDV was working again (I could get data by supplying the channel names manually into get_data), ligoDV could not obtain channel lists for C2 as it could before. Not sure if this is related.

Quote:

looks like you have to work in the lab instead of sitting on the couch 
It's working if you try to get data from there... Or try to tunnel port 8088 through ssh, that should work too. That's the way i usually forward any services which are not accessible from outside.

Time to replace the router....

Quote:

Quote:

Router crashed? Can't get channel list.

- Had Tara restart router, still can't get channel list. Was fine this afternoon.

 nds and daqd both seem to be running on fb0.

 

  1041   Fri Sep 10 01:03:21 2010 DmassElectronicsstuff happensWho cares!

1:40-2:30 HEPA off, AC coupled temperature being written.

 

2:30 -> HEPA low.

 

  1042   Fri Sep 10 01:24:41 2010 DmassElectronicsstuff happensSR560 needed

One of the SR560's I was using to AC couple my nice new temperature sensors is...broken? It's output goes from tiny to railed with a 50 Ohm on the input when switching to a gain of 50. It takes a while to come down off the rail after reseting it. I don't trust its output.

I nicked what looked like a spare SR560 from the TCS lab. Settings when I turned it on were DC coupled, 3 Hz low pass single pole, gain = 20.

  1043   Fri Sep 10 16:32:32 2010 DmassElectronicsstuff happensWho cares!

Quote:

1:40-2:30 HEPA off, AC coupled temperature being written.

 

2:30 -> HEPA low.

 

 4:31-4:47 PM Fri - Noise test on DAQ_GEN4

4:49 - Noise Test on DAQ_GEN3

5:30 or so HEPA on low

9 PM HEPA to off

11 PM HEPA to low

1AM HEPA off

  1229   Mon Dec 20 00:49:55 2010 ranaMiscstuff happenstrivia

KEvsMOMENTUM.png

from the Wikipedia article on Dispersion.

  1353   Tue Mar 15 00:30:46 2011 ZachLaserstuff happensrecent gyro plots are LIES

 Due to an error somewhere in the front end code, the channel that should have been "PLL_ACT" was actually receiving the "CCW_REFL_DC" signal. All data and plots for noise in the PLL actuation readout are absolutely wrong.

Having made sure that I was monitoring the right damn channel, I observe that the PLL actuation noise is once again the same as the AOM actuation signal. This puts us at ~2 x 10-5 (rad/s)/rHz at our most lenient requirement frequency of 200 mHz, or roughly 2700x where we need to be. I currently have and all enclosures shut and all boost engaged (2 for the primary loop and 1 for the secondary). Changing the number of boosts does not affect the low frequency noise relationship between AOM_ACT and PLL_ACT. The secondary loop has >60 dB of OL gain below 50 Hz, so if changing the boosts does not affect the noise then it means that either 1) the same noise that couples into the AOM signal is coupling in independently into the PLL loop and causing the same noise level despite the suppression from the secondary loop, or b) we don't understand how it really works. I cannot see how differential IO noise is not suppressed by the secondary loop gain as measured in the PLL actuation; this just doesn't make sense.

I'm not really sure what else to do. We have isolated all the optics from the open air, and ensured that the locking loops have a pretty solid amount of gain (the secondary loop gain is not astronomical, but it's enough that we should see something) and yet we can't reduce the noise at the transmitted port. The addition of the vacuum system and custom PDs has amounted to a factor of ~5 better noise. Big whoop.

Also, the chamber pressure is now up to about 1.7 torr (no factors of 10 here).

  1354   Tue Mar 15 12:34:33 2011 AlastairLaserstuff happensrecent gyro plots are LIES

 

 Did you change anything since then in the front-end code?  I'm looking at it right now, and it looks like a physical wiring problem not the front-end code.

  1356   Thu Mar 17 15:09:18 2011 AidanMiscstuff happensLVC Lab Tour

Visitors to the lab ...

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  1553   Tue Oct 18 16:38:27 2011 ZachMiscstuff happensATF floppy drive is missing

 Please bring it back---sharing is caring.

  1883   Thu Jun 26 14:48:58 2014 ZachLaserstuff happensCalibration error ruins the day

A riddle: what, besides hard work and dedication, causes a noise reduction? A calibration error!

Despite that the calibration for the open-loop readout is actually very simple, I made an arithmetic error that completely nullifies the apparent recent improvement. The gyro is only as good (or as bad) as it used to be.

I am equal parts embarrassed and disappointed. I truly thought I had seen an improvement, since there were several things I seemed to have fixed that would account for roughly the same enhancement as I thought I saw.

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