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ID Date Author Type Category Subjectup
  12471   Tue Sep 6 00:14:14 2016 gautamUpdateElectronicsSatellite Amplifier

 

If we have some data with one of the optics clamped and the open light hitting the PD, or with the OSEMs removed and sitting on the table, that would be useful for evaluating the end-to-end noise of the OSEM circuit. It seems like we probably have that due to the vent work, so please post the times here if you have them.

The ETMX OSEMs have been attached to its Satellite box and plugged in for the last 10 days or so, with the PD exposed to the unobstructed LED. I pulled the spectrum of one of the sensors (mean detrended, I assume this takes care of removing the DC value?). The DQed channels claim to record um (the raw ADC counts are multiplied by a conversion factor of 0.36). For comparison, re-converted the y-axis for the measured curve to counts, and multiplied the total noise curve from the LISO simulation by a factor of 3267.8cts/V (2^16cts/20V) so the Y axis is noise in units of counts/rtHz. At 1Hz, there is more than an order of magnitude difference between the simulation and the measurement which makes me suspect my y-axis conversion, but I think I've done this correctly. Can such a large discrepancy be solely due to thick film resistors?

Attachment 1: osempdComparison.pdf
osempdComparison.pdf
  12505   Mon Sep 19 13:25:03 2016 TengUpdateElectronicsSatellite Amplifier

 

In order to figure out the difference betweent simulated result and measurement, I tried to measuren the electronic noise by following ways as show in attachment 1

1.measure from the satellite box by SR785 at ETMY ,calibrate to counts by divide by 3267.8. while at that conditin, the set up is in suspension.

2. measure after ADC by diagnostics test tools, with set up on table in history and on uspension currently.

3. use the caculated butterfly channel.

the results are shown in attachmemt 2. The overall nosie level are still much higher than simulation.

 

 

Quote:

 

If we have some data with one of the optics clamped and the open light hitting the PD, or with the OSEMs removed and sitting on the table, that would be useful for evaluating the end-to-end noise of the OSEM circuit. It seems like we probably have that due to the vent work, so please post the times here if you have them.

The ETMX OSEMs have been attached to its Satellite box and plugged in for the last 10 days or so, with the PD exposed to the unobstructed LED. I pulled the spectrum of one of the sensors (mean detrended, I assume this takes care of removing the DC value?). The DQed channels claim to record um (the raw ADC counts are multiplied by a conversion factor of 0.36). For comparison, re-converted the y-axis for the measured curve to counts, and multiplied the total noise curve from the LISO simulation by a factor of 3267.8cts/V (2^16cts/20V) so the Y axis is noise in units of counts/rtHz. At 1Hz, there is more than an order of magnitude difference between the simulation and the measurement which makes me suspect my y-axis conversion, but I think I've done this correctly. Can such a large discrepancy be solely due to thick film resistors?

 

  15799   Wed Feb 10 15:07:50 2021 AnchalSummaryBHDSatellite Amplifier Output Offset measurements

I measured the output DC voltage of the satellite amplifier box at PDMon port when the PDA input was shorted and got following offsets:
 

CH Output Offset (mV) CH Output Offset (mV)
1 6 5 750
2 140 6 120
3 350 7 537
4 40 8 670

However, I think I'm making a mistake while measuring this offset as well as all the noise measurements of this satellite amplifier box so far. Since it is a current input, transimpedance circuit, the noise of the circuit should be measured with open input, not closed. Infact, by shorting the PDA input, I'm giving DC path to input bias current of AD833 transimpedance amplifier to create this huge DC offset. This won't be the case when a photodiode is connected at the input which is a capacitor and hence no DC path is allowed. So my issue of offset was bogus and past two noise measurements in 40m/15797 and 40m/15793 are wrong.

  15800   Wed Feb 10 15:25:45 2021 gautamSummaryBHDSatellite Amplifier Output Offset measurements

Why not just do this test with the dummy suspension box and CDS system? I think Rich's claim was that the intrinsic LED RIN was dominant over any drive current noise but we can at least measure the quadrature sum of the two (which is after all the relevant quantity in terms of what performance we can realize) and compare to a model.

  15801   Wed Feb 10 17:18:03 2021 KojiSummaryBHDSatellite Amplifier Output Offset measurements

Testing the satellite amp i.e.  PD driver
- To test the noise of the PD transimpedance amps:
Leave the PD input open (do not short the terminal goes to the PD)
- To test the current noise of the LED drivers: Short the output with an appropriate Rs to have the nominal current.
- To test the overall noise level together with the LED/PD pair: Connect the dummy OSEM module.

Testing the coil drivers
-
Short the output with an appropriate Rs.

  15776   Mon Jan 25 18:18:04 2021 AnchalSummaryBHDSatellite Amplifier Transfer Functions and noise

 

I took transfer function and noise measurement of satellite amplifier box's photodiode transimpedance circuit. For the measurement, I created a makeshift connector to convert backside DB25 into DB9 with the 4 channels for PDA input. The output was taken in differential form at the front PD Output port. To feed current to the circuit, I put in 12 kOhm resistors in series at the inputs, so the V/V transfer function measured was multiplied by 12 kOhm to get the transimpedance of the circuit.


Transfer Function Measurement details

  • SR785 source out was fed into PDA input pins using a makeshift BNC-DB9-DB25 converter.
  • The output from PDOut DB9 port was fed to test switch in D1900068 to separate differential signal.
  • This differential signal was fed back to SR785 at input 2 in A-B configuration.
  • Measurements are taken with file D1002818_TF.yml and D1002818_TF_LF.yml.
  • A measurement of just cables without the DUT is taken as well.
  • Commands.txt list all the commands used.
  • All data is compiled and plotted in Plotting.ipynb
  • D1100117_S2100029_TFandNoiseSpectrum.pdf shows all the transfer functions measured.

Spectrum Measurements

  • Two pair of BNC cables were twisted together and clips were added at ends.
  • One of the GND was connected to board GND. Rest were left unconnected to avoid ground loops.
  • Each pair of signal was connected to PDOutP/N.
  • The PDA inputs were shorted together to make zero input current to the board.
  • Instrument noise with cables was measured by shorting the clips of the center cores and one of the shields of the two BNC cables together.
  • Measurements were taken with file D1002818_SP.yml and D1002818_SP_LF.yml.
  • Input referred current noise spectrum was calculated by dividing the output voltage noise spectrum by the measured transfer function.
  • D1100117_S2100029_TFandNoiseSpectrum.pdf shows all the output votlage noise spectrum and input referred current noise spectrum measured.

Edit Wed Feb 10 15:14:13 2021 :

THE NOISE MEASUREMENT WAS WRONG HERE. SEE 40m/15799.

Attachment 1: D1002818_S2100029_TFandNoiseSpectrum.pdf
D1002818_S2100029_TFandNoiseSpectrum.pdf D1002818_S2100029_TFandNoiseSpectrum.pdf D1002818_S2100029_TFandNoiseSpectrum.pdf
Attachment 2: D1002818_Testing.zip
  15793   Wed Feb 3 16:27:19 2021 AnchalSummaryBHDSatellite Amplifier Transfer Functions and noise After modifications

I have made modifications recommended in this doc. The changes made are:

  • R24: 19.6k to 4.99k Ohms
  • R20: 19.6k to 4.99k Ohms
  • R23: 787 to 499 Ohms
  • Removed C16.

I took transfer function measurements, fitted them with zeros and poles and plotted it against the zero model of the circuit. The zeros and poles we intended to shift are matching well with 3Hz zero and 30 Hz pole. The later pole at 1500 Hz is at a higher value from what is predicted by zero.

I also took noise measurements and they are in good agreement with the noise predicted by zero.


Edit Wed Feb 10 15:14:13 2021 :

THE NOISE MEASUREMENT WAS WRONG HERE. SEE 40m/15799.

Attachment 1: D1002818_S2100029_TFAfterChanges.pdf
D1002818_S2100029_TFAfterChanges.pdf D1002818_S2100029_TFAfterChanges.pdf D1002818_S2100029_TFAfterChanges.pdf D1002818_S2100029_TFAfterChanges.pdf D1002818_S2100029_TFAfterChanges.pdf D1002818_S2100029_TFAfterChanges.pdf D1002818_S2100029_TFAfterChanges.pdf D1002818_S2100029_TFAfterChanges.pdf
Attachment 2: D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf
D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf
Attachment 3: D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf
D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdf
Attachment 4: D1002812_S2100029_After_Modifications_Feb3.jpg
D1002812_S2100029_After_Modifications_Feb3.jpg
Attachment 5: AfterChanges.zip
  15797   Wed Feb 10 11:45:59 2021 AnchalSummaryBHDSatellite Amplifier Very Low frequency noise After modifications

As suggested, I wrapped the satellite amplifier box D10028128 S2100029 in blanket and foam and took very low frequency spectrum starting from 32 mHz to 3 Hz. The results are attached along with stiched high frequency measurements from 40m/15793.

Very Low Frequency Spectrum Measurement

  • D1002818 S2100029 box was powered and covered in a foam blanket.
  • Additionally, it was covered from all sides with foam to reduce wind and temperature effects on it.
  • The rear panel DB25 connector was connected to a breakout board where pins od PDA input and GND were shorted, shorting the transimpedance circuit input.
  • The output was read from PDMon DB9 output at front panel which was converted to 4 BNC channels using breakout board.
  • Two channel noise was measured at once using D1002818_SP.yml parameter file.
  • Instrument noise at all the used input ranges were measured separately by shorting the input of the BNC cables.

Edit Wed Feb 10 15:14:13 2021 :

THIS MEASUREMENT WAS WRONG. SEE 40m/15799.

Attachment 1: FrontsideLook.jpg
FrontsideLook.jpg
Attachment 2: BacksideLook.jpg
BacksideLook.jpg
Attachment 3: InnerFoamBlanket.jpg
InnerFoamBlanket.jpg
Attachment 4: D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf
D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseLFSpecAfterChanges.pdf
Attachment 5: D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf
D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseLFSpecAfterChanges.pdf
Attachment 6: AfterChangesLFSpectrum.zip
  15803   Thu Feb 11 11:10:05 2021 AnchalSummaryBHDSatellite Amplifier Very Low frequency noise After modifications

Here is a proper measurement for PD transimpedance amplifier circuit in the Satellite amplifier box D1002818 S2100029. The input from rear DB25 connector was left open and measurement was taken with AC coupling with correction by the AC coupling transfer function (Zero at 0, pole at 160 mHz). I have calculated the input referred displacement noise by calculating the conversion factor of OSEM in A/m. From 40m/12470, old conversion factor of OSEM to output of sat amplifier was 1.6 V/mm. then, the transimpedance was 39.2 kOhm, so that must mean a conversion factor of 1.6e3/39.2 A/m. This I scaled with increased drive current by factor of 35/25 as mentioned in this document. The final conversion factor turned out to be around 57 mA / m. If someone finds error in this, please let me know.

There is excess noise in the low-frequency region below 5-6 Hz. If people think I should make a measurement of amplified noise to go further away from the instrument noise floor, let me know.

Attachment 1: AfterChangesSpectrum_AC.zip
Attachment 2: D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf
D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf D1002818_S2100029_OutputNoiseSpecAfterChanges.pdf
Attachment 3: D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf
D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdf
Attachment 4: D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf
D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf D1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf
  15804   Thu Feb 11 16:58:52 2021 ranaSummaryBHDSatellite Amplifier Very Low frequency noise After modifications

I expect that a single OSEM channel can't be better than 1e-10 m/rHz above 5 Hz, so probably something wrong in the calibration. 1.6 V/mm seems right to me, so could be some place else.

  16387   Thu Oct 7 02:04:19 2021 KojiUpdateElectronicsSatellite amp adapter chassis

The 4 units of Satellite Amp Adapter were done:
- The ears were fixed with the screws
- The handles were attached (The stock of the handles is low)
- The boards are now supported by plastic stand-offs. (The chassis were drilled)
- The front and rear panels were fixed to the chassis
- The front and rear connectors were fixed with the low profile 4-40 stand-off screws (3M 3341-1S)
 

Attachment 1: P_20211006_205044.jpg
P_20211006_205044.jpg
  16377   Mon Oct 4 18:35:12 2021 PacoUpdateElectronicsSatellite amp box adapters

[Paco]

I have finished assembling the 1U adapters from 8 to 5 DB9 conn. for the satellite amp boxes. One thing I had to "hack" was the corners of the front panel end of the PCB. Because the PCB was a bit too wide, it wasn't really flush against the front panel (see Attachment #1), so I just filed the corners by ~ 3 mm and covered with kapton tape to prevent contact between ground planes and the chassis. After this, I made DB9 cables, connected everything in place and attached to the rear panel (Attachment #2). Four units are resting near the CAD machine (next to the bench area), see Attachment #3.

Attachment 1: pcb_no_flush.jpg
pcb_no_flush.jpg
Attachment 2: 1U_assembly.jpg
1U_assembly.jpg
Attachment 3: fourunits.jpg
fourunits.jpg
  16378   Mon Oct 4 20:46:08 2021 KojiUpdateElectronicsSatellite amp box adapters

Thanks. You should be able to find the chassis-related hardware on the left side of the benchtop drawers at the middle workbench.

Hardware: The special low profile 4-40 standoff screw / 1U handles / screws and washers for the chassis / flat-top screws for chassis panels and lids

  14417   Thu Jan 24 22:55:50 2019 gautamUpdateElectronicsSatellite box S/N 102 investigation

I had taken Satellite box S/N 102, from the SRM suspension, down to the Y-end as part of debugging. However, at some point, I stopped getting readbacks from the shadow sensor PDs, even with the Sat. Box tester hooked up (so as to rule out anything funky with the actual OSEMs). Today evening, I did a more systematic investigation. Schematic with component references is here.

  1. Used mini-grabbers and a bench power supply to connect +/-24V to C57 and C58.
  2. Checked that all ICs were getting +/- 15 V to the supply pins.
  3. Debugged individual channels, checking voltages at various nodes
    • Found that the "PD K" bias voltage was anomalosly low.
    • Found that the inverting input of U3C wasn't ground.
    • The above findings are summarized in Attachment #2.
    • This suggested something was wrong with the Quad OpAmp LT1125 IC, so I elected to switch it out.
    • During the desoldering process, the pads for the "NC" pins came off (Attachment #1) - this has happened to me before on these old boards. I don't think I applied excess heat during the desoldering (I used 650F).
    • Replaced the IC, and measured the expected 10V at the "PD K" node.
  4. I then connected the tester box and verified all the shadow sensor channels (LED + PD) work as expected, using the front panel J3 and the "octopus cable".
  5. It remains to verify that the coil driver signals get correctly routed through the Satellite box before giving this box a pass certification.

The question remains as to what caused this failure mode - I can't think of why that particular IC was damaged during the Satellite box swapping process - is this indicative of some problem elsewhere in the ETMY OSEM/coil driver electronics chain?

Attachment 1: IMG_7294.JPG
IMG_7294.JPG
Attachment 2: D961289-B2.pdf
D961289-B2.pdf
  14421   Tue Jan 29 17:19:16 2019 gautamUpdateElectronicsSatellite box S/N 105 repaired

[chub, koji, gautam]

Attachment #1 shows the signal routing near the Satellite box. Somehow, the female 64 pin IDC connector that brings the signals from the coil driver board wasn't mating well with the mail connector on the Satellite box front panel. This is a connector specific problem - plugging the female end into one of the male connectors inside the Satellite box yielded signal continuity. The problem was resolved by re-making both connections -by driving the EPICS bias slider through its full range, we were able to see the full voltage swing at the DB connectors going to the flange

This kind of flakiness could be all around the lab, and could be responsible for many of the suspension "mysteries". To re-iterate, the problem seems to be the way the female sockets of the connector mates with the male pins - while the actual crimping points may look secure, there may not be signal continuity.

Now that this problem is resolved, tomorrow we will recover the cavity alignment and possibly start a pumpdown.


Unrelated to this work - the spare satellite box (S/N #100), which had a note on it that said "low voltages", was tested. The "low voltages" referred to the OSEM shadow sensor voltages being low when the LED was completely unobscured. The reason was that the mod to increase the drive current to 25 mA had not yet been implemented on this unit. I added the appropriate 806 ohm resistors, and verified that the voltages were correct, so now we have a working spare. It is stored in the "photodiode" cabinet along the east arm, together with the tester boxes. 

Attachment 1: IMG_7301.JPG
IMG_7301.JPG
  1198   Sat Dec 20 23:37:43 2008 robOmnistructureGeneralSaturday Night Fever after presumed power failure

Just came by to pick something up...

... alarm handlers screeching...

... TP1 failure--closing V1... call Steve... Steve says ok till tomorrow...

... all front ends down (red)...

... all suspensions watchdogged...

... all (I think) servos off...

... PSL shutter closed ...

... chiller at 15C ... I turned it off to prevent condensation in PA...

... MOPA shutter closed... turned off key on Lightwave power supply

... good luck all, and happy holidays!
  1495   Sun Apr 19 03:34:05 2009 YoichiUpdateLockingSaturday night lock
Tonight I was able to go up to arm power = 33, by mainly tweaking the DARM gain. A small progress.
In order to give more phase margin to the CARM MC_L path, I added a 300:100 filter to C1:LSC-MC.
To reduce the load to the lsc computer I deleted several filters from the filter bank, which were not used in the locking scripts.
Before I deleted the filters, I checked in the current chans directory into the svn repository.
If you want to restore the deleted filters, go back to the revision 36142.
  16484   Wed Nov 24 14:34:15 2021 YehonathanUpdateBHDSaving on SUSAUX slow channels

Koji found out that the stock for BIO Acromag modules is very low and that the lead time for ordering new ones is ~ 1-year X-o.

We figure we might need to minimize the number of modules but still keep the Acromag chassis functional.

 

Looking at the new C1AUXEY feed-throughs spreadsheet one can see that we actually normally need only 1 BIO (not 2) module since there are 16 suspensions related bios + 1 green shutter which is unrelated to SUSAUX so there is no room to cut back here.

 

There are 16 analog input channels, 5 for PDMONs and 5 VMONs, and 6 spares which require 2 ADCs. Removing the spares and 2 monitoring channels will be enough to get us to 1 ADC.

  10207   Tue Jul 15 22:23:51 2014 AndresUpdate40m Xend Table upgradeScan the Xarm for the mode matching

 Nick and I with the help of Jenne scan the green light when the cavity is unlocked. Nick placed a Beam dump on the IR so that we can just scan the green, but it was removed as soon as we finished with the measurement. I'm working on the calculation, and i'll be posted solution tonight.

  2499   Sun Jan 10 23:22:56 2010 JenneSummaryGeneralScattering Measurements of 35W Beam Dumps

On Friday, Rana and I measured the scatter coming from the 35W beam dumps.

(These are the ones with big aluminum heat sinks on the back that kind of look like little robots with 2 legs...inside the horn is a piece of polished silicon at Brewster's Angle.)

 

SETUP:

For the measurement, we used the Scatterometer setup at the 40m on the small optical table near MC2. 

We used a frequency of 1743 Hz for the Chopper, and this was also used as the reference frequency for the SR830 Lock-In Amplifier. 

The settings on the Lock-In were as follows:

Input A

24dB/octave

AC coupled

Floating input

"Low Noise"

Time Constant = 1sec

'Scope reading Output A, Output A set to 'Display', and A's display set to "R" (as in magnitude).

Sensitivity changed throughout the experiment, so that's quoted for each measurement.

 

MEASUREMENTS:

White Paper Calibration - white paper placed just in front of Beam Dump.  Sensitivity = 500microVolts.  Reading on 'scope = 7V

Laser Shuttered.  Sensitivity = 500microVolts. 'scope reading = 9mV.

Black Glass at Beam Dump location.  Sensitivity = 500microVolts.  Reading on 'scope = 142mV.   (DON'T touch the glass....measure the same setup with different sensitivity)

Black Glass at Beam Dump location (Not Touched since prev. measurement). Sensitivity = 10microVolts. Reading on 'scope = 6.8V

Laser Shuttered. Sensitivity = 10microVolts. 'scope Reading = 14mV +/- 10mV (lots of fluctuation).

Black Glass Wedge Dump at Beam Dump location. Sensitivity = 10microVolts. 'scope = 100mV.

Beam Dump with original shiny front plate. Sensitivity = 10microVolts.  'scope railing at 11V

Beam Dump with front plate removed. Sensitivity = 10microVolts. 'scope reading = 770mV

Beam Dump, no front plate, but horn's opening surrounded by 2 pieces of Black Glass (one per side ~1cm opening), BG is NOT flush with the opening...it's at an angle relative to where the front plate was.  Sensitivity = 10microV. 'scope = 160mV +/- 20mV.

Beam Dump, no front plate, only 1 piece of Black Glass. Sensitivity = 10microV. 'scope reading = 260mV.

Beam Dump, no front plate, 2 pieces of Black Glass, normal incidence (the BG is flush with where the front plate would have been). Sensitivity = 10microV. 'Scope reading = ~600mV

 

CALIBRATION:

Using our calibration numbers (Black Glass measured at 2 different sensitivities, not touching the setup between the measurements), we can find the calibration between our 2 different sets of measurements (at 500microV and 10microV), to compare our Beam Dump with regular white paper. 

BG at 500uV was 142mV.  BG at 10uV was 6.8V.    6.8V/0.142V = 47.9 

So the white paper, which was measured at 500uV sensitivity, would have been (7V * 47.9) = 335 V in 10uV sensitivity units. 

This is compared to the BG wedge dump at 10uV sensitivity of 100mV, and the Beam Dump reading of 770mV, and the Beam Dump with-black-glass-at-the-opening reading of 160mV.

So our Silicon/Steel horn dump is ~8x worse than a Black Glass wedge and (335 / 0.77) = 435x better than white paper.

We used regular white paper as a calibration because it has a Lambertian reflectance. For some general idea of how to do these kinds of scatter measurements, you can look at this MZ doc.

Assuming that our white paper had a BRDF of (1/pi)/steradian, we can estimate some numbers for our setup:

Sensitivity (signal with the laser shuttered) = (0.02 / 335 / pi) = 2 x 10^-5 / sr.   This is ~3x worse than the best black glass surfaces.

Our wedge = (0.1 / 335 / pi) = 1 x 10^-4 / sr.  Needs a wipe.

Our Silicon-Steel Horn = (0.75 / 335 / pi) = 7 x 10^-4 / steradian.

Our measurements were all made at a small angle since we are interested in scatter back along the incoming beam. We were using a 1" lens to collect the scatter onto a PDA55. The distance from the beam to the center of the lens was ~2" and the detector's lens was ~20" from the front of the horn. So that's an incident angle of ~3 deg.

CONCLUSIONS:

* It seems that any front plate other than Black Glass is probably worse than just having no front plate at all.

* If we put in a front plate, it shouldn't be normal to the incident beam.  Black Glass at normal incidence was almost at the same level as having no front plate. So if we're going to bother with a front plate, it should be about 30deg or 40deg from where the original front plate was.

* No front plate on the Dump is about 7x a Black Glass wedge dump.

* The silicon looks like it might have some dust on it (as well as the rest of the inside of the horn).  We should clean everything.  (Maybe with deionized nitrogen?)

* We should remeasure the Beam Dump using polished steel at a small (30-40deg) angle as the front plate. 

 

ATTACHMENTS:

 * Photos taken with the Olympus camera, which has its IR blocker removed.

* In the photo you can see that we have a lot of reflection off of the horn on the side opposite from the silicon.

* The 2nd picture is of the scatterometer setup.

Attachment 1: P1090014_copy.JPG
P1090014_copy.JPG
Attachment 2: ScatterometerSetup.png
ScatterometerSetup.png
  2507   Tue Jan 12 09:14:52 2010 steveSummaryGeneralScattering Measurements of 35W Beam Dumps

 

 What was the power level, polarization and beam size at beam trap?

  7402   Tue Sep 18 18:24:50 2012 JenneUpdateGeneralScattering in BS chamber or ITMX chamber

I have touched PZT2 such that the beam goes through the 45 degree non-iris target on the beam splitter.  This puts the beam at the center of ITMY, and without moving the BS, at the center of ITMX.  I say "at the center", but what I really mean is I put the target approximately at the center, within what looks like, say, 2 mm, by looking from above.  The target was many (5ish) centimeters away from the optic though, so that's why my side-to-side centering isn't so precise.  Given that, the beam was always more than half going through the hole of the target for both ITMs, so I'm claiming that the spots on the ITMs are within a few mm of center.

With this alignment, the beam was also hitting the center of the SRM (with all the same caveats).

I was able to get the SRM to retroreflect, while I still had Michelson fringing, so I think that I had the SRMI at least close to aligned (I was looking at the SRM retroreflection at the beam splitter, not all the way out to the AS port).  PRM is also pretty easy to align.

We're hitting the top of the AS camera, so I think things are pretty good.  I don't see beam on the REFL camera, but no investigation of that has been done as yet.

There is some scattering going on in the BS / ITMX chambers that's making me kind of unhappy.  I don't know how to get this to embed the youtube video, so here's the embed link, as well as the regular link:

youtube of AS and BS/PRM camera.

<iframe width="420" height="315" src="http://www.youtube.com/embed/QUbnMLXSS5U" frameborder="0" allowfullscreen></iframe>

Manasa watched the camera while I waved an IR card around in the BS chamber, and the only way I was able to get all the scatter spots to go away was to either block the beam incident on the BS (duh), or block the beam reflected off the BS, heading to ITMX.  Manasa said that the scatter spots still looked like they were fringing though, so I'm confused.  I may wave a card around in the ITMX chamber when I come back later tonight, to see what I can see.  Also, I just misaligned the SRM, and the scatter spots moved.  Now there's just some scatter off of what looks like the BS OSEM holders, as seen through the BS optic.

  7948   Mon Jan 28 19:15:14 2013 ManasaUpdateScatteringScattering setup

 [Jan, Manasa]

We are trying to get some scattering measurements in the Y-arm cavity. We have removed one of  the viewport windows window covers of ETMY chamber and have installed cameras on a ring that clamps to the window. The window along with the ring attachment is covered with aluminium foil when not in use.

  7962   Wed Jan 30 11:18:31 2013 ManasaUpdateScatteringScattering setup

Quote:

 [Jan, Manasa]

We are trying to get some scattering measurements in the Y-arm cavity. We have removed one of  the viewport windows window covers of ETMY chamber and have installed cameras on a ring that clamps to the window. The window along with the ring attachment is covered with aluminium foil when not in use.

[Jan, Manasa]

To align the camera to see small angle scattering from the ITMY, we tried shooting a green laser pointer at the pickoff mirror that was installed in the ETMY chamber such that we hit the face of ITMY. But we concluded that to be a very bad way to align the camera because we have no means to reconfirm that the camera was exactly looking at the scattering from ITMY.

Since we are in air, we came up with a plan B. The plan is to temporarily install a mirror in the ITMY chamber to steer the beam from the laser pointer (installed on the POY table) through ITMY to the pickoff mirror at the ETMY end. This way, we can install the camera at the ETMY window and be sure we are looking at ITMY scattered light. 

  7971   Thu Jan 31 11:53:31 2013 ManasaUpdateScatteringScattering setup

Since we are in air, we came up with a plan B. The plan is to temporarily install a mirror in the ITMY chamber to steer the beam from the laser pointer (installed on the POY table) through ITMY to the pickoff mirror at the ETMY end. This way, we can install the camera at the ETMY window and be sure we are looking at ITMY scattered light. 

 [Jan,Manasa]

We executed plan B. We installed the green laser pointer on POY table and steered the beam  through ITMY to hit the pick off mirror at the ETM end by installing *temporary mirrors. The pick off mirror was adjusted in pitch and yaw to center the reflected beam on the viewport window. We have installed irides on the ring attached to the viewport window to direct the beam to the camera.

*Temporary mirrors were removed from the ITMY chamber after this alignment.

  8072   Tue Feb 12 23:22:14 2013 ManasaUpdateScatteringScattering setup

 

 [Jan, Manasa]

We installed a camera at the ETMY end to look at the scattering pickoff from the ITMY. We were able to see the whole of the beam tube. We need to meditate on where to assemble the camera and use appropriate lenses to narrow the field of view such that we avoid looking at scattering from other sources inside the chamber.

  5092   Tue Aug 2 11:52:44 2011 kiwamuSummaryGeneralSchedule

I have updated the 40m public calender.

Main change :

  + The vent starts from 3rd of August

  + Keiko and Anamaria (LSU) come from 13th of August

  16648   Mon Feb 7 09:00:26 2022 PacoUpdateGeneralScheduled power outage recovery

[Paco]

Started recovering from scheduled (Feb 05) power outage. Basically, time-reversing through this list.


== Office area ==

  • Power martian network switches, WiFi routers on the north-rack.
  • Power windows (CAD) machine on.

== Main network stations ==

  • Power on nodus, try ping (fail).
  • Power on network switches, try ping (success), try ssh controls@nodus.ligo.caltech.edu (success).
  • Power on chiara to serve names for other stations, try ssh chiara (success).
  • Power on fb1, try ping (success), try ssh fb1 (success).
  • Power on paola (xend laptop), viviana (yend laptop), optimus, megatron.

== Control workstations ==

  • Power on zita (success)
  • Power on giada (success), run system upgrade.
  • Power on donatella (success)
  • Power on allegra (fail)  **
  • Power on pianosa (success)
  • Power on rossa (success)
  • From nodus, started elog (success).

== PSL + Vertex instruments ==

  • Turn on newport PD power supplies on PSL table.
  • Turn on TC200 temp controller on (setpoint --> 36.9 C)
  • Turn on two oscilloscopes in PSL table.
  • Turn on PSL (current setpoint --> 2.1 A, other settings seem nominal)
  • Turn on Thorlabs HV pzt supply.
  • Turn on ITMX OpLev / laser instrument AC strip.

== YEND and XEND instruments ==

  • Turn on XEND AUX pump on (current setpoint -->1.984 A)
  • Turn on XEND AUX SHG oven on (setpoint --> 37.1 C) (see green beam)
  • Turn on XEND AUX shutter controller on.
  • Turn on DCPD supply, and OpLev supply AC strip on.
  • Turn on YEND AUX pump on (fail) *
    • With the controller on STDBY, I tried setting up the current but got HD FAULT (or according to the manual this is what the head reports when the diode temperature is too high...)
    • Upon power cycling the controller, even the controller display stopped working... YAUX controller + head died? maybe just the diode? maybe just the controller?
      • I borrowed a spare LW125 controller from the PSL table (Yehonathan pointed me to it) and swapped it in.
      • Got YEND AUX to lase with this controller, so the old controller is busted but at least the laser head is fine.
      • Even saw SHG light. We switched the laser head off to "STDBY" (so it remains warm) and took the faulty controller out of there.
  • Turn on YEND AUX SHG oven on (setpoint -->35.7 C)
  • Turn on YEND AUX shutter controller on.

== YARM Electronic racks ==

== XARM Electronic racks ==

 


* Top priority, this needs to be fixed.

** Non-priority, but to be debugged

  16651   Mon Feb 7 16:53:02 2022 KojiUpdateGeneralScheduled power outage recovery

I went to the X end and found it was warm. Turned out that not all the A/Cs were on. They were turned on now.

Attachment 1: PXL_20220208_001646282.jpg
PXL_20220208_001646282.jpg
Attachment 2: PXL_20220208_001657871.jpg
PXL_20220208_001657871.jpg
  16665   Fri Feb 11 11:17:00 2022 AnchalUpdateGeneralScheduled power outage recovery

I found that two computers are not powering up in the control room, Ottavia and Allegra. Allegra was important for us as it had the current version of LIGO CDS workstation installed on, providing us with options to use latest packages written by LIGO CDS team. I think the power issue should be resolvable if someone opens it and knows what thye are doing. Do we have any way of getting fuse repairs on such computers? Both these computers are Dell XPS 420.

 

  16671   Mon Feb 14 21:03:25 2022 KojiUpdateGeneralScheduled power outage recovery

I opened the boxes. Allegra has obvious vent of at least 4 caps. And the power supply did not respond even a paper clip test was performed. https://www.silverstonetek.com/downloads/QA/PSU/PSU-Paper%20Clip-EN.pdf (Paper Clip Test)
=> The mother board and the PSU are dead.

Then Ottavia was also checked. The mother board looked OK, but the PSU did not respond. I quickly opened the PSU and it had a bunch of bulged capacitors in it. => PSU dead

Conclusion: Save the cards/memory etc as much as possible. Migrate the allegra HDD to any other healthy PC or obtain a new used PC from Larry. Otherwise, we just want to buy another WS and copy the disk in it.

 

Attachment 1: PXL_20220215_025325118.jpg
PXL_20220215_025325118.jpg
  16669   Mon Feb 14 18:31:50 2022 PacoUpdateGeneralScheduled power outage recovery - IMC recovery progress

[Paco, Anchal, Tega]

We have been realigning the IMC as of last Friday (02/11). Today we made some significant progress (still at high input power), but the IMC autolocker is unable to engage a stable mode lock. We have made some changes to reach this point, including re-centering of the MC1 REFL beam on the ccd, centering of MC2 QPD trans (using flashes), and centering of the MC REFL RFPD beam. The IMC is flashing to peak transmission of > 50% its max (near 14,000 counts average on 2021), and all PDs seem to be working ok... We will keep the PSL shutter closed (especially with high input power) for now.

  16672   Tue Feb 15 19:32:50 2022 KojiUpdateGeneralScheduled power outage recovery - IMC recovery progress

Reduced the IMC power to 100mW

Setup: The power meter was placed right before the final aperture (Attachment 1)

Before the adjustment: Initial position of the HWP was 37.29deg and the input power was 987mW (Attachments 2/3)

After the adjustment: Initial position of the HWP was 74.00deg and the input power was 100mW (Attachments 4/5)

This made the MCREFL reading 0.549.

The MC refl path optics has not been modified.

Attachment 1: PXL_20220216_001731377.jpg
PXL_20220216_001731377.jpg
Attachment 2: Screen_Shot_2022-02-15_at_16.18.16.png
Screen_Shot_2022-02-15_at_16.18.16.png
Attachment 3: PXL_20220216_001727465.jpg
PXL_20220216_001727465.jpg
Attachment 4: Screen_Shot_2022-02-15_at_16.22.16.png
Screen_Shot_2022-02-15_at_16.22.16.png
Attachment 5: PXL_20220216_002229572.jpg
PXL_20220216_002229572.jpg
  16667   Fri Feb 11 16:09:11 2022 AnchalUpdateGeneralScheduled power outage recovery - Input power increased

We increased the input power to IMC by replacing the 98% transmission BS by a 10% transmission BS on the detection table (reverse of what mentioned in 40m/16408 see attachment 8-9laugh). We then realigned the BS so that MC RFPD is centered. Then we realigned two steering mirrors to get the beam centered on the WFS1 and WFS2 QPD. Then we increased the power of the input beam to get 5.307 reading on the C1:IOO-MC_RFPD_DCMON channel. We did this so that we can align the IMC. Once we have it aligned, we'll go back to low poer for doing chamber work.

Beware, there is about 1W beam on the detection table right now.

 

  16655   Wed Feb 9 16:43:35 2022 PacoUpdateGeneralScheduled power outage recovery - Locking mode cleaner(s)

[Paco, Anchal]

  • We went in and measured the power after the power splitting HWP at the PSL table. Almost right before the PSL shutter (which was closed), when the PMC was locked we saw ~ 598 mW (!!)
  • Checking back on ESP300, it seems the channel was not enabled even though the right angle was punched in, so it got enabled.
    • No change.
  • The power adjustment MEDM screen is not really working...
  • Going back to the controller, press HOME on the Axis 1 (our HWP) and see it go to zero...
    • Now the power measured is ~ 78 mW.
  • Not sure why the MEDM screen didn't really work (this needs to be fixed later)

We proceeded to align the MC optics because all offsets in MC_ALIGN screen were zeroed. After opening the PSL shutter, we used values from last year as a reference, and try to steadily recover the alignment. The IMC lock remains at large.

  16657   Thu Feb 10 15:41:00 2022 AnchalUpdateGeneralScheduled power outage recovery - Locking mode cleaner(s)

I found out that the ESP300 service needs to be run in root mode for it to be able to connect to the USB port of HWP motor controller. While doing this change, I noticed that the channels hosted by c1psl might have a duplication conflict with some other channel hosting computer, because a lot of them show the Warning: "Identical process variable names on multiple servers" which is not good. Someone should look into this conflict.

I added instructions on the power control MEDM screen as it was very non-trivial to use. I have set the power such that the C1:IOO-MC_RFPD_DCMON is 5.6 and this happened at C1:IOO-HWP_POS_SET 2.29.

  16658   Thu Feb 10 17:57:48 2022 AnchalUpdateGeneralScheduled power outage recovery - Locking mode cleaner(s)

Something is wrong with the Video MUX. The system did not turn back on with full functionality. Even though we see the screens as they were before the power shutdown, we have lost control on switching any of the videos. I went to check the wiki page about Video MUX which told be we should be able to see the configuration screen on this link, but the page wasn't opening. I went and removed the power cable and put it back in. That brought back the configuration page. Still, I could not change any of the video feeds however this time, I could see the EPICS channel values (like C1:VID-QUAD1_4) change. I tired to go to the configuration page and change the matrix values from the control tab there. I found out that the matrix was mislabeled and while making the changes, I started seeing blue screen on QUAD1_3 (where MC2T was set before). I set the QUAD1_3 (output 23) to MC2T (input 16), but no change. The EPICS values are also set properly, so I don't understand the reason behind blue screen. The same happened when I tried to use:

~>/opt/rtcds/caltech/c1/scripts/general/videoscripts videoswitch3 QUAD1_3 MC2T

Weirdly, this caused the QUAD1_4 screen to go blue. Running following had no effect:

~>/opt/rtcds/caltech/c1/scripts/general/videoscripts videoswitch3 QUAD1_4 MCR

So, I'm not sure what to do. This really needs to be fixed! I wanted to see teh MC2F camera so that I can align IMC, that was the whole reason for this rabit hole. Help needed.

Attachment 1: PXL_20220211_021509819.jpg
PXL_20220211_021509819.jpg
  16659   Thu Feb 10 19:03:23 2022 KojiUpdateGeneralScheduled power outage recovery - Locking mode cleaner(s)

I came back to the 40m and started the investigation.

If I ping 192.168.113.92, it responds. But telnet (port 23) was rejected. I somehow tried ssh and it responds! I even could login to the host using usual password. Here is the prompt.

controls@nodus|~> ssh 192.168.113.92
controls@192.168.113.92's password:

...
controls@c1sus2:~ 0$

Oh no...

Looks like c1sus2 and the videomux have the IP address conflict.

Here are the useful ELOG links:

https://nodus.ligo.caltech.edu:8081/40m/4498

https://nodus.ligo.caltech.edu:8081/40m/4529

  16660   Thu Feb 10 19:46:37 2022 KojiUpdateGeneralScheduled power outage recovery - Locking mode cleaner(s)

== Assign new IP address to c1sus2 ==

cf: [40m ELOG 16398] [40m ELOG 16396]

- Shutdown c1sus2 (Oh, no. This killed c1lsc/c1sus/c1ioo... This should be taken care of later)

- Confirmed 192.168.113.87 is not alive

- Go to chiara
- Modify /diskless/root/etc/hosts

192.168.113.87  c1sus2 c1sus2.martian

- Modify /etc/dhcp/dhcpd.conf

host c1sus2 {
  hardware ethernet 00:25:90:06:69:C2;
  fixed-address 192.168.113.87;
}

- Modify /var/lib/bind/martian.hosts

c1sus2          A    192.168.113.87
videomux        A    192.168.113.92

- Modify /var/lib/bind/martian.hosts/rev.113.168.192.in-addr.arpa

87            PTR    c1sus2.martian
92            PTR    videomux.martian

- Reload/restart bind9 / dhcpd. Run the following command

sudo service bind9 reload
sudo service isc-dhcp-server restart

- Restart c1sus2 and confirm if the IP address was actually changed

controls@c1sus2:~ 0$ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 00:25:90:06:69:c2
          inet addr:192.168.113.87  Bcast:192.168.113.255  Mask:255.255.255.0
...

== Restart c1lsc / c1sus /c1ioo ==

- Reboot c1lsc/c1sus/c1ioo

- Go to scripts/cds

- Run startC1LSC.sh and follow the instruction

 

  15956   Wed Mar 24 00:51:19 2021 gautamUpdateLSCSchnupp asymmetry

I used the Valera technique to measure the Schnupp asymmetry to be \approx 3.5 \, \mathrm{cm}, see Attachment #1. The data points are points, and the zero crossing is estimated using a linear fit. I repeated the measurement 3 times for each arm to see if I get consistent results - seems like I do. Subtle effects like possible differential detuning of each arm cavity (since the measurement is done one arm at a time) are not included in the error analysis, but I think it's not controversial to say that our Schnupp asymmetry has not changed by a huge amount from past measurements. Jamie set a pretty high bar with his plot which I've tried to live up to. 

Attachment 1: Lsch.pdf
Lsch.pdf
  16264   Wed Jul 28 17:10:24 2021 AnchalUpdateLSCSchnupp asymmetry

[Anchal, Paco]

I redid the measurement of Schnupp asymmetry today and found it to be 3.8 cm \pm 0.9 cm.


Method

  • One of the arms is misalgined both at ITM and ETM.
  • The other arm is locked and aligned using ASS.
  • The SRCL oscillator's output is changed to the ETM of the chosen arm.
  • The AS55_Q channel in demodulation of SRCL oscillator is configured (phase corrected) so that all signal comes in C1:CAL-SENSMAT_SRCL_AS55_Q_DEMOD_I_OUT.
  • The rotation angle of AS55 RFPD is scanned and the C1:CAL-SENSMAT_SRCL_AS55_Q_DEMOD_I_OUT is averaged over 10s after waiting for 5s to let the transients pass.
  • This data is used to find the zero crossing of AS55_Q signal when light is coming from one particular arm only.
  • The same is repeated for the other arm.
  • The difference in the zero crossing phase angles is twice the phase accumulated by a 55 MHz signal in travelling the length difference between the arm cavities i.e. the Schnupp Asymmetry.

I measured a phase difference of 5 \pm1 degrees between the two paths.

The uncertainty in this measurement is much more than gautam's 15956 measurement. I'm not sure yet why, but would look into it.

 

Quote:

I used the Valera technique to measure the Schnupp asymmetry to be \approx 3.5 \, \mathrm{cm}, see Attachment #1. The data points are points, and the zero crossing is estimated using a linear fit. I repeated the measurement 3 times for each arm to see if I get consistent results - seems like I do. Subtle effects like possible differential detuning of each arm cavity (since the measurement is done one arm at a time) are not included in the error analysis, but I think it's not controversial to say that our Schnupp asymmetry has not changed by a huge amount from past measurements. Jamie set a pretty high bar with his plot which I've tried to live up to. 

 

Attachment 1: Lsch.pdf
Lsch.pdf
  4821   Wed Jun 15 01:30:38 2011 JamieSummaryLSCSchnupp asymmetry measurement

Measurement of Schnupp asymmetry

This was done by measuring the relative phase between the sidebands reflected from the two arms while the arm cavities are locked.

The Schnupp asymmetry is measured to be:   Lsa = 3.64 ± 0.32 cm

schnupp.png

Description:

As a phase reference we use the zero crossing of the response function for the out-of-phase control signal for the single arm cavity lock [0]. The difference in the RD rotation phase of the response zero crossings indicates the phase difference in the sideband signals reflected from the arms. Assuming the asymmetry is less than half the RF modulation wavelength [1], the asymmetry is given by the following formula:

       \Delta \phi   c   1 
L_sa = ----------- ----- -
           360     f_RSB 2

We use a LSC digital lock-in to measure the response of the arm cavity at a single-frequency drive of it's end mirror.

[0] The locations of the zero crossings in the out-of-phase components of the response can be determined to higher precision than the maxima of the in-phase components.

[1] fRSB = 55 MHz,     c/fRSB/2 = 2.725 m

Procedure:

  1. Lock/tune the Y arm only.
    • We use AS55_I to lock the arms.
  2. Engage the LSC lock-in.
  3. Tune the lock-in parameters:
  4. lock-in freq: 103.1313 Hz
    I/Q filters:  0.1 Hz low-pass
    phase:        0 degrees
    
  5. Set as input to the lock-in the out-of-phase quadrature from the control RFPD.  In this case AS55_Q->LOCKIN.
  6. Drive the arm cavity end mirror by setting the LOCKIN->Y_arm element in the control matrix.
  7. Note the "RD Rotation" phase between the demodulated signals from the control PD (AS55)
  8. For some reasonable distribution of phases around the nominal "RD Rotation" value, measure the amplitude of the lock-in I output.
    • Assuming the Q output is nearly zero, it can be neglected.  In this case the Q amplitude was more than a factor of 10 less than the I amplitude.
    • Here we take 5 measurements, each separated by one over the measurement bandwidth (as determined by the lock-in low pass filter), in this case 10 seconds.  The figure above plots the mean of these measurements, and the error bars indicate the standard deviation.

The data and python data-taking and plotting scripts are attached.

Error Analysis:

To to determine the parameters of the response (which we know to be linear) we use a weighted linear least-squares fit to the data:

y = b X

where:

X0j = 1
X1j = xj              # the measurement points
y = yi                 # the response
b = (b0, b1)     # line parameters

The weighting is given by the inverse of the measurement covariance matrix. Since we assume the measurements are independent, the matrix is diagonal and Wii = 1/\sigmai2 The
estimated parameter values are given by:

\beta  =  ( XT W X )-1 XT W y  =  ( X'T X' )-1 X'T y'

where X' = w X, y' = w y and wii = \sqrt{Wii}.

The X' and y' are calculated from the data and passed into the lstsq routine. The output is \beta.

The error on the parameters is described by the covariance matrix M\beta:

M\beta = ( XT W X)-1 = ( X'T X')-1

with correlation coefficients \rhoij = M\betaij / \sigmai / \sigmaj.

The x-axis crossing is then given by:

X(Y=0) = - \beta1 / \beta0

References:

Valera's LLO measurement
http://en.wikipedia.org/wiki/Weighted_least_squares
http://en.wikipedia.org/wiki/Linear_least_squares_(mathematics)#Weighted_linear_least_squares
http://en.wikipedia.org/wiki/Error_propagation

Attachment 2: arm_phase.py
#!/usr/bin/env python

import sys
import os
import subprocess
import time
import pickle
from numpy import *
import nds
import matplotlib
... 229 more lines ...
Attachment 3: plot.py
#!/usr/bin/env python

import pickle
from numpy import *
import matplotlib
#matplotlib.use('AGG')
from matplotlib.pyplot import *

##################################################

... 137 more lines ...
Attachment 4: schnupp_ETMX.pik
(dp0
S'I'
p1
(dp2
cnumpy.core.multiarray
scalar
p3
(cnumpy
dtype
p4
... 341 more lines ...
Attachment 5: schnupp_ETMY.pik
(dp0
S'I'
p1
(dp2
cnumpy.core.multiarray
scalar
p3
(cnumpy
dtype
p4
... 341 more lines ...
  6151   Tue Dec 27 16:56:15 2011 kiwamuUpdateLSCScmitt trigger installed
The old trigger system has been replaced by Schmitt triggers in the c1lsc realtime model.
They seem working correctly.
  

      An example              

Here below is a picture of time series showing how the Schmitt trigger works as an example.
trigger_time_series.png
 
 In order to check the new trigger, I injected a fake sine signal into the TRY path to simulate lock acquisition of the Y arm with TRY used as a trigger.
Then I monitored the trigger signal, called C1:LSC-YARM_TRIG_MON.
This variable is a boolean, and hence it returns zero when the trigger is off and one when it is on.
I set the upper and lower thresholds to be 0.6 and 0.2 respectively.
As shown in the picture, the trigger became on when the TRY sine curve crossed the upper threshold of 0.6.
After that the TRY signal then crossed the lower threshold of 0.2 and the trigger became off.
 

      How to set the thresholds         

The setting procedure is the same as before.
  1. Open the trigger matrix window, which is accessible from the C1LSC overview screen as usual.
  2. Then type the desired upper and lower thresholds into the column.

The below is a screenshot of the trigger matrix screen. The thresholds column is pointed by a big white arrow.

 trig_mat.png

Of course, DO NOT set the upper threshold value to be smaller than that of the lower threshold. Otherwise it won't correctly work.

Also if you want to have the usual trigger rather than the Schmitt trigger, simply put the upper and lower thresholds at the same values.

 

 

      Details         

 Here I explain how the new trigger exactly work.
The attached screen shot below is the actual c1lsc simulink model, zoomed in the blocks of the MICH trigger.
model_trigger_edit.png
 
    The signal flows from the left hand side to the right hand side and the resultant output is always either zero or one.
There are two variables, which you can control via EPICS: TRIG_THRES_ON and TRIG_THRES_OFF.
Those two variables correspond to the upper and lower thresholds respectively.
   An important thing is that there are two key components: "UnitDelay" and "Choice" blocks.
First of all the code checks whether the trigger used to be ON or OFF at the "Choice" block by looking at the TRIG_MON data which is from the past.
The "Choice" block is configured such that if the TRIG_MON value used to be True, it lets the TRIG_THRES_OFF signal go through.
And if the TRIG_MON used to be False, then it lets the TRIG_ON signal go through.
Therefore this procedure breaks the situation into two cases : trigger used be ON and OFF, and depending on the situation it returns a proper threshold.
     After this check, the code does the usual triggering.
The proper threshold from the "Choice" block will be compared with an LSC signal at ">" block.
If the LSC signal is greater than the threshold value then it gives one and enables the feedback.
 
  3935   Tue Nov 16 21:42:31 2010 ranaUpdateCDSScreen Time Fix
I learned today that the following python code will do a find/replace to fix the TIME string on any MEDM screen which has a whited out time field.
Previously, this field was sourced from the c1dscepics of c1losepics process. Now we have to get it from the IOO or SUS front ends

Here's the python code:

import re
o = open("output.adl","w")
data = open("test.adl").read()
o.write( re.sub("C0:TIM-PACIFIC_STRING","C1:FEC-34_TIME_STRING",data)  )
o.close()

Where 'output.adl' could be the same name as 'test.adl' if you want to
replace the existing file. Also FEC-34 just refers to which FE you're running.
It could, in principle, be any one of them.
 

The next step is to figure out how to apply this to all the files in a directory.

  3938   Wed Nov 17 10:39:20 2010 josephbUpdateCDSScreen Time Fix

An improved python code to apply a replacement to all *.adl files in a directory would be:

import re, os
files = os.listdir("./")
  for file in files:
    if ".adl" in str(file):
      data = open(file).read()
      o = open(file,"w")
      o.write( re.sub("C0:TIM-PACIFIC_STRING","C1:FEC-34_TIME_STRING",data)  )
      o.close()

Of course, this entire python script can be replaced with a single sed command:

sed -i 's/C0:TIM-PACIFIC_STRING/C1:FEC-34_TIME_STRING/g' *

A more complicated script could be written which looks for key identifiers either in the file header or inside the file to determine which front end is appropriate, using a dictionary like:

dcuid_dict = {"BS":21,"PRM":37,"SRM":37,"ITMX":21,"ITMY":21,"MC1":36,"MC2":36,"MC3":36,"ETMX":24,"ETMY":26}

and then using for loops and if statements.

 

  3652   Tue Oct 5 16:30:00 2010 josephb, yutaHowToCDSScreen settings and medm screens for new system

You can find the sitemap medm screen in

/opt/rtcds/caltech/c1/medm/master

The settings for the screens were last saved by burt in the original system on Sept 29, 2010 at 11:07.  So go to the

/cvs/cds/caltech/burt/autoburt/snapshots/2010/Sep/29/11:07

directory.  You can grep for the channels in the files in this directory.

You can also then use the autoBurt.req file in the /opt/rtcds/caltech/c1/target/sysname/sysnameepics (c1sus/c1susepics) to backup the settings entered.  Save to the /opt/rtcds/caltech/c1/target/snapshots directory for now.

 

 

  5772   Mon Oct 31 19:39:00 2011 JenneUpdateAdaptive FilteringScreens, code, computers

[Mirko, Jenne]

I finished (mostly? maybe?) the OAF screens.  They're pretty awesome. 

While we were playing with the OAF, trying to do some oafing, the output of the code decided to just be zeros.  We did a test, and in the c-code set the output to be a constant value, and that worked.  But when we put it back to normal (being adaptive) and recompiled, it still only outputs zeros.  The code is receiving both witness and error signals, so we don't know what's going on.

In the course of trying to make things work again, we did a complete reboot of c1lsc and c1sus.  Did a burt restore.  Everything (except our weird code problem) should be fine again.  Optics are damping happily.

  1617   Thu May 21 18:07:32 2009 ranaUpdatePSLScrew on Needle valve loosened
Alberto and I went in to loosen up the needle valve yesterday around 4:30 PM. The idea was to cut down on
the flow to the NPRO so that the cooling power of the chiller would be used almost entirely on the
amplifier instead of the NPRO block.

The need valve was basically all the way open. The lock nut was screwed in all the way and stuck. By using
pliers and a wrench for the nut, we freed the lock nut. Even so, the screw for the needle valve seemed to
be bad: I think the thread is stripped; it doesn't go down even after several turns. I even tried to squirt
alchohol on it and really press down in the hopes of catching a thread. It may have closed slightly but its
impossible to be sure.

I also increased the NPRO diode current to the max (+0.1 A). This got us a little bit of NPRO power and
I hope some more AMPMON stability. The attached plot shows 4 days of minute trend. If you squint you
might believe that we got some suppression in the HTEMP fluctuations over the last two days.
Attachment 1: Untitled.png
Untitled.png
  13078   Fri Jun 23 02:55:18 2017 KaustubhUpdateComputer Scripts / ProgramsScript Running

I am leaving a script running on the Pianoso for the night. For this purpose, even the AG4395A is kept on. I'll see the result of the script in the morning (it should be complete by then). Just check so before fiddling with the Analyzer.

Thank you.

  5634   Fri Oct 7 22:41:05 2011 KojiConfigurationGeneralScript backup fixed

Script backup regularly runs on op340m by crontab,
but the true backup were not taken since Oct 16, 2010
as the backup program was looking at the old script directory.
/cvs/cds/script/backupScripts.pl was modified to look at the new script directory.

OLD COMMAND:

$command = "cd /cvs/cds/caltech; /usr/sbin/tar cfX - $EXCLUDE_LIST scripts | bzip2 > $ARCHIVEDIR/scripts_$curdate.tar.bz2";

NEW COMMAND:

$command = "cd /opt/rtcds/caltech/c1; /usr/sbin/tar cfX - $EXCLUDE_LIST scripts | bzip2 > $ARCHIVEDIR/scripts_$curdate.tar.bz2";

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