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ID Date Author Type Categoryup Subject
  7414   Wed Sep 19 23:17:25 2012 ranaConfigurationPSLAOM installation

Mannasa and Unni and I looked at the RF driver for the AOM. It was fine.

With the ALC input left unconnected, with the power supply set to +28V, it was drawing 0.56 A.

By adjusting the modulation input we were able to get 1.1 Vrms into the scope (terminated at 50 Ohms) after going through 2 10dB attenuators. 11 Vrms into 50 Ohms is 33.8 dBm ~ 2W.

The RF power trimpot on the front of the driver is now adjusted so that -0.31 to 0.69 V takes the driver output from off to 2W output at 80 MHz.

 

The previous distorted signal that Jan and Manasa saw was at a level of ~100 mVrms, which is ~0.5 mW of power. At this tiny drive level, the internal amplifier is not linear and is mostly putting out a signal at ~160 MHz.

 

We checked by putting a square wave into the modulation input that the RF power from the driver would indeed shut off with a time scale of ~20 ns. Manasa will add a picture to this entry. We are ready now to calibrate the transmitted power of the AOM v. the modulation input voltage and then to measure the step time of the AOM.

Remember: do NOT believe the spec sheet of whatever PD you are using. All commercial PDs are slower than they advertise. In order to measure a <1 us step time you must use a PD with a >50 MHz 'bandwidth'.

  7416   Thu Sep 20 01:29:04 2012 ManasaConfigurationPSLAOM installation

Quote:

Mannasa and Unni and I looked at the RF driver for the AOM. It was fine.

With the ALC input left unconnected, with the power supply set to +28V, it was drawing 0.56 A.

By adjusting the modulation input we were able to get 1.1 Vrms into the scope (terminated at 50 Ohms) after going through 2 10dB attenuators. 11 Vrms into 50 Ohms is 33.8 dBm ~ 2W.

The RF power trimpot on the front of the driver is now adjusted so that -0.31 to 0.69 V takes the driver output from off to 2W output at 80 MHz.

 

The previous distorted signal that Jan and Manasa saw was at a level of ~100 mVrms, which is ~0.5 mW of power. At this tiny drive level, the internal amplifier is not linear and is mostly putting out a signal at ~160 MHz.

 

We checked by putting a square wave into the modulation input that the RF power from the driver would indeed shut off with a time scale of ~20 ns. Manasa will add a picture to this entry. We are ready now to calibrate the transmitted power of the AOM v. the modulation input voltage and then to measure the step time of the AOM.

Remember: do NOT believe the spec sheet of whatever PD you are using. All commercial PDs are slower than they advertise. In order to measure a <1 us step time you must use a PD with a >50 MHz 'bandwidth'.

Attachment 1: TEK00000.PNG
TEK00000.PNG
  7425   Fri Sep 21 12:12:56 2012 ManasaConfigurationPSLAOM installation

    {Jan, Manasa}

We installed the AOM driver back on the PSL table this morning. To calibrate the AOM RF output we connected a 1V dc to the modulation input of the driver and we are convinced with the setup.

Before we direct the rf signal to the AOM, in order to check its diffraction efficiency, we would like to setup an rf PD at the AOM output. We think we have place for a filter and PD after the AOM (replacing a beam dump) and would like to confirm the position before we actually install them. The layout is the picture below showing sweet spots for the new pd to sit. If you think it may disturb the system in any way, let us know!

PSL.png

  7464   Tue Oct 2 16:15:22 2012 ManasaConfigurationPSLAOM installation

Quote:

    {Jan, Manasa}

We installed the AOM driver back on the PSL table this morning. To calibrate the AOM RF output we connected a 1V dc to the modulation input of the driver and we are convinced with the setup.

Before we direct the rf signal to the AOM, in order to check its diffraction efficiency, we would like to setup an rf PD at the AOM output. We think we have place for a filter and PD after the AOM (replacing a beam dump) and would like to confirm the position before we actually install them. The layout is the picture below showing sweet spots for the new pd to sit. If you think it may disturb the system in any way, let us know!

 

The rf PD and filter have been installed at the earlier proposed spot on the PSL table.  

psl_aom.png

  7471   Wed Oct 3 16:52:16 2012 ManasaConfigurationPSLAOM installation

{Jan, Manasa}

We set start to check the performance of the AOM on the PSL table. The AOM driver spits out ~1.5W rf at 80MHz for 1V DC at its modulation input. In order to align the AOM, we reduced the input power to the AOM to ~10% using the QWP between the PBS and the laser. We touched the steering mirror before the AOM...but did not succeed in getting any appreciable first order deflection. We then released the AOM mount and moved it a few microns in and out until we obtained a significant change in power along the zero-order beam from 400mV to 100mV when the rf power was changed from 0 to ~1.5W (by changing modulation input from 0 to 1V).  The AOM was clamped at this alignment and the QWP was rotated to give maximum input power. 

During the course of aligning the AOM, the PMC unlocked and was restored after the alignment. 

All went well without having to make any emergency calls to anyone

We will now have to think about switching the AOM on and off for ringdown measurements. This could be done by either using a high-power rf switch or by switching the modulation DC input between 0 and 1V; whichever will be more comfortable to take many many ringdown measurements.

 

  7474   Wed Oct 3 23:36:54 2012 KojiConfigurationPSLAOM installation

After the AOM work the beam wasn't well aligned to the PMC. The PMC REFL CCD shows large misalignment in yaw.

Attachment 1: PMCTRANS.png
PMCTRANS.png
  7479   Thu Oct 4 17:54:59 2012 ManasaConfigurationPSLAOM installation

Quote:

After the AOM work the beam wasn't well aligned to the PMC. The PMC REFL CCD shows large misalignment in yaw.

 {Jan, Manasa, Den}

We wanted to align the PMC and followed Koji's procedure detailed to us by mail. We touched the 2 steering mirrors in front of the PMC for alignment.

- Stand in front of the PMC.
- Find an oscillosocpe on the shelf in the PSL enclosure.
- This has two signals connected. One is the PMC refl dc.
  The other is the PMC trans dc.
- Minimize the refl. Maximize the trans.
- You have the CRT monitor on the MC chamber.
- Project the image of the PMC refl CCD.
  This should show some what symmetric image like an LG mode.
- Use the dataviewer to see how C1:PSL-PMC_PMCTRANSPD is recovered.

We were able to obtain 0.7 at PMC trans; but the PMC was never really stable dropped from 0.7 to 0 abruptly from time to time.

Jenne and Jamie also find that the PMC is behaving very weird 

Summary: Problem unresolved 

 

  7480   Thu Oct 4 18:48:04 2012 janoschConfigurationPSLAOM installation

Quote:

Jenne and Jamie also find that the PMC is behaving very weird 

 Can someone detail what "weird" means? Is it singing old songs from Guns & Roses?

  7481   Thu Oct 4 20:57:43 2012 ManasaConfigurationPSLAOM installation

Quote:

Quote:

Jenne and Jamie also find that the PMC is behaving very weird 

 Can someone detail what "weird" means? Is it singing old songs from Guns & Roses?

 It isn't singing Jan..it's dancing between 0.7 to 0 and we are not able to figure out whose the DJ ; there seems to be something else that is controlling the PMC as there is no coordination between what we do (tweaking the mirrors) and what we observe (the PD signals).

  7482   Thu Oct 4 22:16:28 2012 KojiConfigurationPSLAOM installation

Do more investigation to understand what is causing the power reduction.

Is the alignment inadequate? Check the in-lock ccd image.

Is the incident power reduced? (by what?) Use dataviewer.

Is the AOM doing something? Is it active? Then how much power is it eating?

BY THE WAY, how the deflected beam is dumped?
If you don't have anything for blocking the 1st order beam, you have to expect Steve coming to you.

  7483   Thu Oct 4 22:16:40 2012 DenUpdatePSLPMC is locked

PZT monitor is not lying to us, I've measured it with a voltmeter. But PMC SERVO is still interesting. If I break the loop after PMCERR signal monitor (C1:PSL-PMC_BLANK=0), I can change PZT voltage from 0V (C1:PSL-PMC_RAMP = -7.3) to 132V (C1:PSL-PMC_RAMP=-10.0). If I break the loop by enabling TEST1, PZT voltage goes up to 294 V, though voltage on the TEST1 and MIXER MON is 0.

  7492   Fri Oct 5 14:53:29 2012 JenneUpdatePSLTTFSS board not fully seated!

[Den, Jenne]

Den noticed that the -15V LED on the TTFSS board was not illuminated.  A further symptom of the FSS being funny was that the PC RMS Drive was constantly high (3.6 ish) and the FAST Monitor was very high, often saturated. 

We took the TTFSS board out, and put an extender card in, and it looked like all of the correct power is being supplied to the board (the +\- 24V LEDs on the extender card were illuminated).  Just to check, we put the board back in, and this time both +\- 15V LEDs came on.  So it looks like the board is fine, it just wasn't seated in there all the way.

Now the readbacks on the FSS screen look good (PC RMS Drive is less than 1, FAST Mon is 5ish), the MC is locked, and I think we're back in business. 

 

  7494   Fri Oct 5 18:08:17 2012 ManasaConfigurationPSLAOM installation

Quote:

Do more investigation to understand what is causing the power reduction.

Is the alignment inadequate? Check the in-lock ccd image.

Is the incident power reduced? (by what?) Use dataviewer.

Is the AOM doing something? Is it active? Then how much power is it eating?

BY THE WAY, how the deflected beam is dumped?
If you don't have anything for blocking the 1st order beam, you have to expect Steve coming to you.

The PMC has been aligned and is all happy happy 

I have installed an  iris to dump the higher order beams deflected by the AOM. After installing the iris, I found that the PMC trans dropped to 0.58V and the PMC misaligned in pitch. So I've touched the 2 steering mirrors before the PMC. Now it is satisfactorily locked with PMC trans at 0.84.

I have also checked the alignment with AOM switched on. PMC trans drops to 0.15 with AOM on and comes back to 0.84 when AOM is switched off without losing lock .

  7501   Mon Oct 8 11:15:53 2012 JenneUpdatePSLPMC and FSS had a weird weekend

Something bizarre-o was going on with the PMC and FSS over the weekend.  On the striptool, PMC's PZT looks like it was doing a sawtooth pattern for several hours.  I opened up the FSS screen, and the FSS SLOWDC had walked itself up to +10.  It's not supposed to get that far from 0. 

Here are some trends, so you can see what was going on.

10 day trend:  This weird behavior began ~Friday evening (FSS_SLOWDC ramps quickly).

PMC_sawtooth_FSSweird_8Oct2012_10dayTrend.png

1 day trend:  You can see the sawtooth pattern in PMC_PZT more clearly here.  It's at the same time as the FSS_SLOWDC is ramping rapidly, and the FSS_FAST is saturated.

PMC_sawtooth_FSSweird_8Oct2012_1dayTrend.png

Attachment 2: PMC_sawtooth_FSSweird_8Oct2012_1dayTrend.png
PMC_sawtooth_FSSweird_8Oct2012_1dayTrend.png
  7590   Mon Oct 22 21:20:36 2012 JenneUpdatePSLBeam attenuation optics in place

[Jenne, Raji (before dinner)]

We put the beam attenuation optics in place.  Before putting any optics down, I centered the IOO QPDs, then adjusted the HWPs and PBS such that we remained centered on those QPDs.

Now, I'm about to unblock the beam and let ~100mW into the vacuum so I can lock the MC.  Steve and Manasa were putting on the light access connector when I left earlier, so I'm excited to use it!

  7766   Fri Nov 30 11:38:35 2012 SteveUpdatePSLfoil removed from enclosure

Aluminum foil replaced by sheet metal on Enclosure and AP table.

Attachment 1: IMG_1822.JPG
IMG_1822.JPG
  7778   Mon Dec 3 17:04:12 2012 AyakaUpdatePSLPMC calibration for MC_F calibration

In order to calibrate MC_F signal, I need to know the calibration value from thorlab's PZT driver to laser frequency.
The calibration value should be ~ 15MHz/V (the PZT driver has 15 gain, and the laser has the calibration value of ~ 1MHz/V according to the laser spec sheet), but I want to confirm it.
This can be measured by sweeping the input voltage of the PZT driver and see the transmission signal from unlocked PMC.
 

1. Response of PMC transmission when the signal is inputted to laser PZT

I inputted 0.2 Hz triangular wave with 5Vamp and 2.5V offset into the PZT driver and see the transmission signal from PMC. After the PZT driver and before the laser, there is an analog low pass filter but its cut off frequency is 1 Hz so I did not take it into consideration. 
DSC_4955.JPGsweep_PZTdriver.png(TEK00000.CSV, TEK00001.CSV in the zip file)

I could not the side-band resonances. I guess it was because the generated signal is not big enough (but still the maximum range of the signal generator.)
Therefore, in order to calibrate the input voltage to the frequency, I need to know finesse or FWHM frequency.
 

2. Responce of PMC transmission when the voltage of PZT on the PMC is swept

In order to measure the finesse and FWHM frequency, I also swept the PMC PZT voltage with the DC offset slider at the FSS.adl and tried to measure the finesse of PMC. (reference: elog #904)
PMC_PZT_FSR.pdftrans_fit.png(PMC-PZTcal_121203.xml in the zip file)

The result of fitting:

V_FSR (the PZT voltage difference between the 2 resonances) ~ 63 +/- 7 V (= 731MHz (given))
V_FWHM (the PZT voltage to sweep FWHM) ~  0.32 +/- 0.04 V (~ 3.7 MHz)
Finesse ~ 200 +/- 30

However, this finesse value is much smaller than the value on the Wiki, 800. (Manasa showed me.)
V_FSR is comparable to the result Rana got at the referenced elog. But I am not sure about the V_FWHM because it is hard to figure out how large the PZT voltage changed from the template file (PMC-PZTcal.xml).
Are those mode wrong? But if so, where is the correct mode resonances? I think they should be visible...
 

3. Calibration value 

When I know the FWHM frequency, I can calibrate the input on the PZT driver into laser frequency.

The results are:

if I take the finesse of 800 and FSR of 731 MHz (the values on the Wiki): ~5.0 MHz/V
if I take the finesse of 200 and FSR of 731 MHz (the measured value): ~20.0 MHz/V

Actually, the measured value is closer to the value calculated from the spec sheet.

Hmm... Does anyone find falses in my measurement?
If not, the finesse can be 4 times smaller than the value which was 5 years ago?

Attachment 5: PMC-PZTcal_121203.zip
  7779   Tue Dec 4 01:43:37 2012 ranaUpdatePSLPMC calibration for MC_F calibration

  If you can't find the PMC sidebands in the transmission, its because the SNR is too small.

It may be a better idea to look at the PMC error signal, since the DC signal there is suppressed by the demodulation.

  7782   Tue Dec 4 11:30:36 2012 ZachUpdatePSLPMC calibration for MC_F calibration

In order to have less unknown, you can calibrate the PMC PZT separately. Lock the PMC and take a transfer function from either the NPRO PZT input or the FSS AOM VCO input to the PMC control signal. The VCO is better, since the calibration should be much better known, but I am not sure what the current setup of the 40m PSL is, so I don't know if the FSS is normally locked.

Since you know the NPRO PZT or VCO actuation coefficients, you can assume the PMC loop (where the OL gain is high enough) is correcting for the frequency fluctuations. So, simply multiply the known coefficient by the transfer function to get the PMC PZT gain.

Then, you can re-do your PMC PZT sweep measurement and be confident of the calibration. The FSR must be right, so you can get the finesse with confidence.

Quote:

Hmm... Does anyone find falses in my measurement?
If not, the finesse can be 4 times smaller than the value which was 5 years ago?

 

  7810   Tue Dec 11 11:40:07 2012 Manasa, AyakaUpdatePSLPMC drift

[Manasa, Ayaka]

I found that MC got unstable this morning. This is caused by the drift of PMC. The transmission of PMC was going down and eventually unlocked PMC.

PMCdrift121211.pdf

We adjusted 'Slow Actuator Adjust' in FSS and now the PMC is locked with transmission of ~ 0.735.
Also we aligned the MC to be locked. Now it is locked with transmission of ~ 0.5 with WFS and MCL on.

  7811   Tue Dec 11 19:51:36 2012 KojiUpdatePSLPMC gain was too low / EPICS alerting value for PMC updated

[Ayaka, Koji]

Ayaka pointed out that the PMC has too low unity gain frequency. We checked the history of "C1:PSL-PMC_GAIN"
and found that the gain was minimum from the Friday night. It was returned to nominal gain of 10.

The PMC screen had the gain status indicator always red. This was because C1:PSL-STAT_PMC_NOM_GAIN was 2 instead of 10.
This was fixed by the following command.

ezcawrite C1:PSL-STAT_PMC_NOM_GAIN 10

This will be recorded by the snapshot in an hour.

Another annoying false alerm on the PMC screen was the PMC transmission monitor.
In order to fix this, the following commands were executed.

ezcawrite C1:PSL-PMC_PMCTRANSPD.LOLO 0.75
ezcawrite C1:PSL-PMC_PMCTRANSPD.LOW 0.8
ezcawrite C1:PSL-PMC_PMCTRANSPD.HIGH 0.9
ezcawrite C1:PSL-PMC_PMCTRANSPD.HIHI 0.95

Also the corresponding EPICS database (/cvs/cds/caltech/target/c1psl/psl.db) has been updated accordingly.

  7823   Thu Dec 13 17:24:53 2012 AyakaUpdatePSLPMC calibration for MC_F calibration

 I calibrated MC_F signal into Hz/rtHz unit using the transfer function from MC_F to PMC feedback signal.

Here is the diagram:
  MC-PMCservo.jpg

n_mcf is MC_F signal we can get at dtt. I measured n_pmc/n'_mcf using SR.

TF_mcf-pmc.png

Other information I used:

G_out = 2.49/123.49 (see the document D980352-E01-C)

Fout has 1 pole at 10 Hz (see the document D980352-E01-C)

A_pzt = 371e+6/63 [Hz/V] (see elog)

F_wt has 1 pole at 100 Hz and 1 zero at 10 Hz.

Then, calibration transfer function of H is fitted as 1e+9/f [Hz/V]:

H.png

Then, the calibrated spectrum of MC_F is below:

 MCF_calib.pdf

This calibration have about 20 % error.
Compared to the spectrum in Jenne's paper (elog), above 20 Hz it seems to be laser frequency noise. But now we have extra unknown noise below 10 Hz.

Note: calibration value of laser's PZT is ~ 1MHz/V. This is reasonable compared to the data sheet of the laser. (This is calculated by combining result of H and transfer function of the circuit box1 and FSS.)

 laser.png

Attachment 6: calib.zip
  7836   Fri Dec 14 17:12:19 2012 Evan HallUpdatePSLPMC yaw tune-up (from Wednesday night)

Wednesday night, there was ~0.4 V on the PMC transmission PD. I adjusted the steering mirrors into the PMC and got the transmission up to 0.81 V.

  7895   Mon Jan 14 09:08:37 2013 SteveUpdatePSLPMC is only ok short term

 

 The PMC PZT voltage slider seemed sticky.  First it would not do anything, than after moving slider back an forth a few times, it had a range of 60V and later it had full range and it locked

Attachment 1: pmc8d.png
pmc8d.png
  7983   Fri Feb 1 12:34:55 2013 JenneUpdatePSLToo much power injected into vacuum

I noticed (while relocking the MC after Jamie and I zeroed the LSC offsets) that the MC refl power was 4.8 V.  Usually we should be ~4.2, so I closed the PSL shutter and went in to measure the power.  We were injecting ~125mW or a little more.  I had adjusted the power the other day, and through yesterday, it looked fine, but overnight it looks like it drifted up.

  8077   Wed Feb 13 16:31:08 2013 JenneUpdatePSLPMC pitch input tuned, MC yaw input tuned

[Jenne, Yuta]

I looked at PMCR camera on the MC1 tv, and tweaked up the beam going into the PMC - it only needed a little bit of pitch.

Yuta and I measured the MC spots, determined (consistent with my measurements this morning) that they were only off in yaw.  We touched the 2nd steering mirror in the zigzag on the PSL table in yaw a small amount (top of knob away from me), realigned the MC, and things were good.  The plot is zoomed in to show only measurements taken today.  2 in the morning, before anything in the IFO room was touched.  1 this afternoon after tweaking PMC.  1st attempt at PSL beam tweaking was successful, 2nd measurement confirms it wasn't a fluke.

MCspots_13Feb2013.png

  8130   Thu Feb 21 16:53:37 2013 ManasaUpdatePSLPSL shutter

[Steve, Jenne, Yuta, Manasa]

We have kept the laser ON at low power through the pump down process. As we pumped down, at around 400torr, we found that the PSL mech shutter closed. Steve explained  that it was due to an interlock with a pressure gauge. To keep the IFO running, we switched the shutter from N.C (normally close) to N.O (normally open). This should be undone after the pumpdown.

In the process of figuring out, we reset the shutter and switched it ON and OFF a couple of times.

  8263   Fri Mar 8 21:00:05 2013 ManasaUpdatePSLPMC fixed

Quote:

  Mystery

1. Filter module (FM1) on PRCL and MICH show significant delay while enabling and disabling.

2. I tried to fix PMC alignment (PMC trans was 0.76). I was not able to get PMC trans more than 0.79.
PMC has been this way since yesterday.

3. MICH is still bright when locked (ASDC_OUT reads 0.08 for dark and 2.0 for bright). We suspect it is because of the AS55_I error offset that persists even after running LSCoffsets script.

4. PRMI shows some dither at 3Hz when locked.

 [Koji, Manasa]

PMC is fixed with 0.84 in transmission. It was misaligned in pitch (fixing this increased PMC_trans to 0.822 from 0.773) and Koji also touched the wave plate and polarizer (changed PMC_trans to 0.845).

  8264   Sat Mar 9 19:29:27 2013 KojiUpdatePSLModulation depth

Last night I measured the modulation depth of the MC incident beam.


Method:

The beam is taken from one of the  PO beam at the wedge plate before the IMC.
After removing the knife edge to dump this beam, the beam is sent to the west side
of the PSL table and put into the OSA cavity.
[The beam dump was returned after the measurement.]

I had some confusion and after all I use the OSA labeled as AS OSA rather than the one on the PSL table.
[The AS OSA was returned to the AP table.]

The transmission was detected by PDA255 and filtered by ITHACO 1201 preamp with G=10, no HPF, 30kHz LPF.
It was confirmed that the peak amplitudes are not reduced by the LPF filter. The resulting time series
was recorded by an oscilloscope.

Three measurements have been taken. The 11MHz peaks are offset by the carrier peak. They appropriately
removed. The ratio of the sideband and carrier peaks is converted to the modulation depth using the following formula.

P_sb / P_ca = [J1(m)/J0(m)]^2


Measurement

The modulation depth for the 11MHz: 0.190 +/- 0.003

The modulation depth for the 55MHz: 0.2564 +/- 0.0003

The three scans showed very similar numbers. That's why the statistical error is such small.
I don't think the systematic error is not such good.

This number is much different form the previous meaurement by Mirko.

http://nodus.ligo.caltech.edu:8080/40m/5519 m=0.14 (11MHz) & 0.17 (55MHz)
but the measured voltages and the modulatio depths are inconsistent.

http://nodus.ligo.caltech.edu:8080/40m/5462 m=0.17 (11MHz) & 0.19 (55MHz)

Probably the modulation depths should be checked by the IMC again.
However, it is certain that the 55MHz modulation exists, and even larger than the 11MHz one.

The next is to confirm that the modulation frequency is matched with the IMC FSR.
It is to make sure that the modulation is transmitted to the main IFO without attenuation.

Attachment 1: mod_depth.pdf
mod_depth.pdf
  8421   Mon Apr 8 08:05:41 2013 SteveUpdatePSLPMC locked

The PMC locked manually. MC  grabbed lock instantaniously

  8422   Mon Apr 8 10:19:46 2013 JenneUpdatePSLLSC left enabled

 

 Note: The TRY PD isn't installed and normalized properly yet, so the IFO OVERVIEW screen indicates lock for the Yarm constantly, which is not true.  Hopefully in the next day or so the screen will be back to telling the truth.

Also, the LSC Locking was left ENABLED (presumably over the weekend).   This is not so good.  It can kick optics around, so we should all take a look when we walk through the control room, and if no one is locking, please disable the LSC master switch. 

  8424   Mon Apr 8 22:43:44 2013 ranaUpdatePSLMC locking troubles: MC/FSS servo unstable

The MC seemed to be losing lock recently quite a bit. I noticed that the PC Drive RMS signal was red.

This means that the high frequency drive to the Pockels cell was too high by a factor of 2-3 and sometimes saturating and breaking the lock.

I fiddled with the gains on the FSS screen until this value went down. It looks like there is some kind of high Q oscillation; it takes a couple minutes for the PC Drive RMS to settle to its new position after changing the gains.

The attached trend plot show the last 2 hours. The mean is now back to ~1 V and seems OK. We should really examine the FSS or MC error point spectra with the RF analyzer while exploring this gain space.

Attachment 1: Untitled.png
Untitled.png
  8429   Tue Apr 9 07:48:10 2013 SteveUpdatePSLPMC locked

Quote:

The PMC locked manually. MC  grabbed lock instantaniously

 PMC locked

Attachment 1: pmc10d.png
pmc10d.png
  8435   Wed Apr 10 07:37:33 2013 SteveUpdatePSLPMC locked

Quote:

Quote:

The PMC locked manually. MC  grabbed lock instantaniously

 PMC locked

 PMC locked.

Attachment 1: pmc4d.png
pmc4d.png
  8460   Thu Apr 18 02:51:52 2013 DenUpdatePSLFSS slow servo

Today Rana pointed out that our FSS slow servo is malfunctioning. It has been for a while that our laser temperature control voltage drifted from 0 to 10.

I looked at FSSSlowServo script that runs at op340m and controls the servo. Script disables the servo when MC transmission is less then FSS_LOCKEDLEVEL. But his value was set to 0.2 probably till reference cavity time.

This means that slow servo was not disabled when MC was unlocked. I changed this value to 7000.

Also I increased integral gain from 0.0350 to 0.215 such that fast control is always in the range 4.5 - 5.5

  8470   Mon Apr 22 12:03:58 2013 KojiUpdatePSLPMC aligned too

PMC aligned. C1:PSL-PMC-PMCTRANSPD improved from 0.72ish to 0.835ish.

  8542   Tue May 7 18:42:20 2013 JamieUpdatePSLPMC not locking

I'm just now realizing that the PMC has also not been locked since noon today, and doesn't seem to be responding to anything right now.

wtf is going on here?

  8545   Tue May 7 20:09:10 2013 Jamie, RanaUpdatePSLPMC problem was FSS slow actuator

Rana showed up and diagnosed the problem as a railed FSS SLOW output.  The SLOW Monitor about was showing ~6V, which is apparently a bad mode-hoppy place for the NPRO.  Reducing the SLOW output brought things back into a good range which allowed the PMC to lock again.

In attempting to diagnose the problem I noticed that there is -100 mV DC coming out of the PMC RFPD RF output.  This is not good, probably indicating a problem, and was what I thought was the PMC lock issue for a while.    Need to look at the PMC RFPD RF output.

  8546   Tue May 7 20:35:15 2013 ranaUpdatePSLPSL database / screen maintenance
  1. Fixed LOCKMC screen to display the SLOWM voltage instead of the ref cav transmission.
  2. PSL Status .db file updated to trigger on correct limits for FSS FAST and the FSS and PMC local oscillator levels.
  3. SETTINGS_SET screen can now take and display screen snapshots.

All of these changes were committed to the SVN.

  8689   Fri Jun 7 21:33:39 2013 ManasaUpdatePSLPSL green to Y- BEAT PD blocked

To allow Annalisa to work on the Y-green alignment as I work with the X-green, the part of the PSL green beam that goes to the Y-green beat PD has been blocked with an iris.

  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
ELOG V3.1.3-