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ID Date Authorup Type Category Subject
  8562   Sat May 11 01:11:52 2013 KojiUpdateASCPRC mode stabilization with a shadow sensor at POP

Ah, AWESOME. Indefinite PRMI lock was finally achieved.

POP setup

- Looked at the POP setup. Checked the spot on POP110 PD. Found some misalignment of the beam.
  The beam spot was aligned to the PD with PRMI locked. The value of POP110I almost doubled by the alignment
  and recovered previous value of 400. Therefore previous normalization values of MICH 0.01 / PRCL 100 were restored.

- Placed PDA36A (Si 3.6mmx3.6mm) on the POP path that Jenne prepared. The gain knob was set to 40dB.
  Since the original spot had been too small, a lens with f=50mm was inserted in order to expand the beam.
  Connected the PD output to the SMA feedthrough on the ITMX table enclosure.
  I found the BNC cable labeled "PO DC" hanging. Connected this cable to the enclosure SMA.

- Went to the LSC rack. Found the corresponding PO DC cable. Stole the POPDC channel from POP110I Bias T to this PO DC cable.

- Razor blade setup: Machined a junk Al bracket in order to fix a razor blade on it. Attached the Al bracket to a sliding stage.

Locking

- Locked the PRMI with REFL33I&AS55Q. Cut the beam into half by the razor blade.

- Made a temporary PRM_ASC_YAW filter.
  Zero: 0Hz Pole: 2kHz
  Resonant Gain 3.2Hz Q:2 Height 30dB
  Butterworth 2nd-order 60Hz

  => Expected UGF 0.1Hz&10Hz

- CDS: By the work described in this entry, the POPDC signal was connected to the "MC" bank of the LSC.
            BTW, the 11th row of the LSC output matrix is connected to the PRM_ASC_YAW.

- The "MC" servo input (i.e. the POPDC signal) was normalized by POP110I (without SQRTing).

- Engaged the PRM ASC path. Gradually increased the gain of PRM_ASC_YAW. G=+100 seemed to be the best so far.
  It was visible that the spot on the POP CCD was stablized in yaw.

- The lock lasted for ~40min. Took several measurements, alignment adjustment, etc.

- Tweaking the PRM ASC unlocked the PRMI.

- Locked again. Switched from REFL33I/AS55Q (x1/x1) combination to REFL55I/REFL55Q (x1/x0.3) combination.
  This also kept the lock more than 20min.

Attachment 1: Screenshot.png
Screenshot.png
Attachment 2: 130510_PRMI.pdf
130510_PRMI.pdf
  8566   Mon May 13 23:05:26 2013 KojiConfigurationLSCPRMI locking

- Disabled MCL path in mcdown/mcupscript.

Nominal gain in mcdown/mcup was -50 and -100 respectively.

- Confirmed the stable lock was just because of the quiet seismic of the Friday night.

- Improvement of the PRM ASC servo
RG3.2 (3.2Hz Q=2 Height 30dB)
=>
RG3.2 (3.2Hz Q=10 Height 30dB) +  zero[f, 1, .5] pole[f, 2, 3] zero[f, 4.5, .5] pole[f, 3.5, 3]

Filter shape comparison is found in the second plot attached.

The resulting spectra (freerun vs controlled) is found in the first plot.

Nominal PRM ASC gain is +70

- Openloop TF measurement

OLTF PRCL 250Hz 30deg / MICH 200Hz 45deg

- REFL55/REFL33 phase adjustment (in lock)

REFL55 phase fine tune (95.25deg) (x1,x0.3)
REFL33 phase (-13.0deg) (x1, x2)

Attachment 1: 130513_PRC_ASC.pdf
130513_PRC_ASC.pdf
Attachment 2: 130513_PRC_ASC_servo.pdf
130513_PRC_ASC_servo.pdf
  8570   Tue May 14 02:19:13 2013 KojiUpdateGreen LockingXend Green tweaked

Note that I'm supposed to return one of the two green beat PDs and the power supply.
They are on the REFL path. I'll work on the restoration of the beat configuration.

  8574   Tue May 14 20:27:19 2013 KojiConfigurationLSCOpenloop gain for PRMI lock May 13

The OLTFs for PRCL and MICH for the last night's lock were modelled using Yuta's python script.

Attachment 1: LSCPRCLOLTF.png
LSCPRCLOLTF.png
Attachment 2: LSCMICHOLTF.png
LSCMICHOLTF.png
Attachment 3: 130513.zip
  8591   Thu May 16 11:50:25 2013 KojiConfigurationElectronicsMeasurement and empirical models of the AI board TFs

Yesterday, I pulled out the AI board for the PRM/BS SUSs. (After the investigation it was restored)

Contrary to our expectation, the board D000186 was not Rev. A but Rev. B.

According to Jay's note in D000186 (for Rev.D), the differences of the Revs are as follows

Rev.A: Initial Release (Analog Biquad version, 4dB 4th order elliptic with notches)
Rev.B: Filter implemented by Freq Devices chip
Rev.C: Differential input version with better RF filtering
Rev.D: 3rd order 0.5dB ripple Cheby with notches at 16K&32K, DB25 input version


I went to the WB EE shop and found bunch of AI filter modules. At least I found one Rev.A and six Rev.D.
I found at least one Rev. C.

I took Rev.A and Rev. D to see the difference of the transfer functions.
Rev.A has more ripple but steeper roll-off. Rev. D is flater at the pass band with slower roll-off.
Rev.D has more phase lag, but it will be fine once the entire frequency response is shifted to x4 high frequency.
The notch frequency of the Rev. D looked right.

I made the empirical pole/zero modeling of the transfer functions.
The LISO models are attached as the ZIP file.
I faced an unexplainable phase behavior at around one the notches for Rev.A.
This may suggest there could have been internal saturation is the stage during the sweep.

More importantly, Rev. D has differential inputs although the connector formfactor is different from the current 40pin IDC.
In fact we should not use Rev.A or Rev.B as they have single end inputs.
Currently the inputs of the AI's for the SUSs are single ended while the DACs are differential.
This means that
1) We waste a half of the DAC range.
2) The negative outputs of the DACs are short-circuited. OMG
3) The ground level fluctuation between the DAC and the SUS rack fluctuates the actual actuation voltage.

Now I am looking at the noise performance of the filters as well as the DAC output noise and range.
I hope we can use Rev.D by replacing the connector heads as this will remove many of the problems we currently have.

Attachment 1: D000186AD_TF.pdf
D000186AD_TF.pdf
Attachment 2: D000186AD_TF.zip
  8592   Thu May 16 22:03:16 2013 KojiConfigurationLSCY Green BBPD returned to the PSL table

I borrowed the GTRY BBPD  for the REFL165 trial before.

Now the PD is back on the PSL table.

The PD is intentionally misaligned so that anyone can find it is not aligned.

  8599   Fri May 17 19:56:52 2013 KojiSummaryCDSWeird DAC bit flipping at half integer output values

Let me make a complimentary comment on this effect.

Because of this oscillation feature, we have a 32kHz peak in the DAC spectrum rather than a 64kHz peak.

For advanced LIGO, the universal AI (D070081) was made to have 3rd-order 10kHz LPF with 64kHz notch.
If we have a higher peak at 32kHz (where the rejection is not enough) than at 64kHz, the filter does not provide
enough filtering of the DAC artifacts.

For the 40m, the original filter had the cut off of 7kHz as the sampling rate was 16kHz.
If we want to extend the frequency range by 4times, the correspoding cut off should be 28kHz.
The rejection is again not enough at 32kHz.

If this peak is an avoidable feature by using simple sample&hold the peak freq is pushed up to
64kHz and we can use the AI filters as planned.

  8601   Mon May 20 18:47:47 2013 KojiUpdateLSCPRMI sensing matrix - not high quality data

For now forget about the demodulation phase and assume all of the ports are independent.
I want to know the numbers in the following format.

          PRCL     MICH   (unit: cnt/m)
REFL11I:  x.xxxEx x.xxxEx
REFL11Q:  x.xxxEx x.xxxEx
REFL33I:  x.xxxEx x.xxxEx
REFL33Q:  x.xxxEx x.xxxEx
REFL55I:  x.xxxEx x.xxxEx
REFL55Q:  x.xxxEx x.xxxEx
REFL165I: N/A     N/A
REFL165Q: N/A     N/A
AS55I:    x.xxxEx x.xxxEx
AS55Q:    x.xxxEx x.xxxEx

If you really want to resolve the TF phase difference between the I and Q  demod-signals,
you need to look at the transfer functions between the excitation and these ports.
We can't understand what is happening only from the single point measurement.

  8611   Wed May 22 00:08:19 2013 KojiUpdateLSCSensing matrix scripts modified to include actuator calibration

It was too embarassing to see that the actuation frequency was set at the violin mode frequency in order to avoid designing a new filter!?

I ran Jenne's sensing matrix code and the immitated the same result by manual measurement with DTT.
I noticed that the PRM excitation was not transmitted to the mirror. I tracked down the cause and found that
Jenne is using 628Hz which is the notch frequency of the viloing filter.

There is no way we can measure the precise calibration of the error signal exactly at the violin mode frequency.

Nevertheless I waited for the ringdown of the violin mode to the floor level and ran the code again WITH the violin mode filter OFF
at PRM SUS.

The result was stored in the data file

sensematPRM_2013-05-22.12615.dat

The code spit the message at the end

Sensing Matrix, magnitude only, units = cts/meter
 
            MICH          PRCL         
AS55        5.304E+08     1.716E+09     
REFL11      1.732E+13     2.151E+11     
REFL33      1.616E+11     5.384E+09     
REFL55      1.681E+11     6.950E+09

Now I replicated the same measurement with DTT.

MICH or PRCL were excited with the lockin. In order to aviod the violin mode, I shifted the excitation freq by 1Hz. (i.e. 629.125Hz)

The peaks in REFL33I/Q and RFL55I/Q were observed with PSD and TF. The spectrum was measured with the FLATTOP window with the line resolution of 0.1Hz
DTT suggested that this corresponds to the BW of 0.471271Hz if I correctly understood what DTT plot said. We need this information to convert cnt/rtHz to cnt_pk
if we need. For the TF measurements, I needed to find the excitatin monitor but I could not. Therefore, I set the offset of LSC-LOCKIN1_SIG to be 1000,
so that C1:LSC-LOCKIN1_I_IN1 produce the same signal as the excitation.

Note that during the measurement, 628Hz nothces in the LSC servos were on. I confirmed that this provides the reduction of the feedback by a factor of 76.
As the original openloop gain at 629Hz is lower than the unity more than a factor of 2, this was sufficient attenuation to measure the optical gain with the systematic error of less than a %.

MICH excitation (ITMX -1, ITMY +1)
        PSD (cnt/rtHz)   TF Mag    Phase

REFL33I 0.098590         9.5691e-5 74.4344
REFL33Q 0.019294         1.8665e-5 71.1204
REFL55I 0.016123         1.3890e-5 77.3132
REFL55Q 0.157522         1.5285e-4 91.5594

PRCL excitation (PRM +1)
        PSD (cnt/rtHz)   TF Mag    Phase

REFL33I 15.7565          1.5298e-2 -109.727
REFL33Q  0.171648        1.6310e-4 -141.73
REFL55I 16.2834          1.5809e-2 -109.672
REFL55Q  0.634096        6.1012e-4 -143.169

These measurements are saved in the XML files (for DTT) in
/cvs/cds/caltech/users/koji/130521/
as
130521_MICH_EXC.xml and 130521_PRCL_EXC.xml

As the actuator of the PRM/ITMX/ITMY are {19.6, 4.70, 4.66}/f^2 nm/cnt, the optical gains were calculated from the TF measurements.

MICH excitation (ITMX -1, ITMY +1)
        OPTICAL GAIN
(cnt/m)
REFL33I 4.0e9
REFL33Q 7.9e8
REFL55I 5.9e8
REFL55Q 6.5e9

PRCL excitation (PRM +1)
        OPTICAL GAIN

REFL33I 3.1e11
REFL33Q 3.3e9
REFL55I 3.2e11
REFL55Q 1.2e10

These should be compared with the measurement by the script and we get more information from the script (like AS55, REFL11)

  8612   Wed May 22 00:42:13 2013 KojiSummarySUSviolin Q

While looking at the decay of the violin mode of the PRM, I made a simple measurement of the decay rate.

Error signal: REFL33I

The peak @628Hz became 0.372 to 0.303 in 60 sec.

-> Half life of the amplitude T_{1/2} is 203sec.

Q = 4.53 f0 T_{1/2} = 5.8 x10^5

  8614   Wed May 22 11:21:28 2013 KojiSummaryCDSWeird DAC bit flipping at half integer output values

Is this limit cycle caused by the residual of the digital AI filtering at the half sampling freq and that his the threshold?
Or is this some nonlinear effect? If this is a linear effect associated with the zero-padding, the absolute
value of the DC may affect the amplitude of the oscillation. (Or equivalently the range of the DC where we get this oscillation.)

Anyway, it seems that we should use no-zero-padding.

You pointed out the ringdown of the digital AI filter in the sample-hold case (i.e. no-zero-padding case).
How does it look like in the conventional zero-padding case?

  8616   Wed May 22 15:08:37 2013 KojiSummaryCDSWeird DAC bit flipping at half integer output values

It seems that the effect is from the (linear) residual fluctuation of the digital AI filter for the zero-padded signal.

Namely, if we give the larger constant number, we get more oscillation.

Attachment 1: Screenshot.png
Screenshot.png
  8629   Thu May 23 13:14:34 2013 KojiSummaryLSCXarm beat note search continues

We should consider to hook up the temperature monitors of the NPROs to the ADCs.

  8631   Thu May 23 17:51:39 2013 KojiSummaryLSCMy usual locking procedure

For purpose of the automation and my record, I summarized my locking procedure as a chart.

Attachment 1: PRMI_locking_procedure.pdf
PRMI_locking_procedure.pdf PRMI_locking_procedure.pdf
  8636   Thu May 23 22:13:12 2013 KojiUpdateLSCPRMI sensing matrix measured at 580.1Hz

Can you clarify the definition of the phase "0deg" of your plot?

Is "I" the definition of "0deg"? Or does the demod phase of "0deg" define "0deg"?

I want to know if the demod phase of REFL55 is correctly adjusted or not.

With the decent level of the separation, we should be able to keep the decent lock of PRMI with REFL55.

  8638   Fri May 24 11:38:00 2013 KojiUpdate40m upgradingETMY - Mode Matching for green

I got confused. Is the mode calculation in the cavity correct?
Are you sure the wavelength in the code is 532nm?

The first plot says "the waist radius at ITMY is 2.15mm". This number is already very close to
the waist size of the cavity mode (2.1mm@ITM, 3.7mm@ETM), but the spot radius at ETMY is 6mm.
They are inconsistent.

 

  8641   Fri May 24 14:01:59 2013 KojiUpdateLSCPRMI sensing matrix measured at 580.1Hz

It's hard to believe but is AS55Q really almost insensitive to MICH?

Well, anyway, now it is the time to use the automatic demod phase (and input matrix) adjustment.

  8650   Tue May 28 17:06:04 2013 KojiUpdateLSCPRMI sensing matrix: Got it!

- We want to add POX11/POY11 in the collection. They may indicates some abnormal asymmetry between two arms (for PRMI).

- We also want to PRCL/MICH after the input matrix. This will be useful when we want to adjust the input matrix to give the optimul
demod phase for the two signals from a single port.

  8690   Fri Jun 7 23:44:54 2013 KojiUpdateGeneralProjector - lightbulb replaced

http://nodus.ligo.caltech.edu:8080/40m/7885

  8708   Fri Jun 14 07:06:19 2013 KojiSummaryGreen LockingX arm ALS

It's nice that we are now able to scan the cavity again. We got close to PRMI+one arm one step further.
The calibration of the scan frequency and the evaluation of the in-loop/out-of-loop error signal in terms of (Hz/rtHz) would be necessary.

The beat amplitude looks actually huge aIthough I don't know where you are monitoring.
Talk to Jamie to figure out how much the signal should be at the monitoring point.
If it is more than we are supposed to have, put an attenuator somewhere.

  8716   Tue Jun 18 07:22:20 2013 KojiUpdateLSCSensing Matrix vs. Schnupp Asymmetry

Interesting.
What's the reason why the PRMI/MICH ratio gets worse (larger) for 55MHz and 165MHz for the DRMI compared to the PRMI case?

  8723   Wed Jun 19 04:56:07 2013 KojiUpdateASCmodel name ASS -> ASC ???

Sounds good.
Or we just stuff any angle control things in to Angular Stabilization System without changing the model name.
The process name itself is not a big deal.

  8744   Tue Jun 25 11:39:13 2013 KojiUpdateLSCArm Cavity scan with X-ALS after ALS servo upgrade

My understanding is that that number is an in-loop evaluation of the loop so far (as the first step of the loop evaluation).
This is not what we can directly compare with the number in the paper.

Basically the entry 8741 is telling us that the new filter suppresses the error signal better than before.
That's clearly shown in the attachment 2.

Quote:

Quote:

RMS is now less than 1 kHz or ~50 pm. (in your face, Kiwamu!)

 Isn't this still a factor of 2 away from the limit in the paper?

 

  8783   Fri Jun 28 12:15:09 2013 KojiUpdateLSCNeed to measure sensing matrix at REFL165

There is no sensible REFL165 PD in the lab. I am supposed to prepare a new version of REFL165 using prototype BBPD.

  8797   Wed Jul 3 14:33:46 2013 KojiSummaryLSCTest result for the REFL165 photodetector

P.1 Circuit diagram

Added components are indicated by red symbols.

- The diode on the board is HAMAMATSU S3399. It is a Si PIN diode with φ3.0 mm.

- Based on prototype version of aLIGO BBPD D1002969-v8 (although the board says v7, It is v8.)

- The input impedance of the MAR-6SM amplifier (50Ohm) provides the transimpedance.

- The first notch (Lres and Cresa/b) is actually not notch but a LF rejection with DC block.

- The second and third notches are tuned to 11MHz and 55MHz.

- Another notch is implemented between the RF amps. The 33MHz signal is weak so I expected
to have no saturation at the first amplifier.

- As you see from the DC path, the transimpedance of the DC path is 2k V/A. If this is too high,
  we need to replace R9 and R11 at the same time. TP1 is providing +10V such that the total
  reverse bias becomes 25V without bringing a special power supply.

P.2 Transimpedance

The transimpedance is measured with an amplitude modulated diode laser.

The transimpedance is 1k V/A ish. It is already at the edge of the bandwidth.
If we need more transimpedance at 165MHz, we should replace
the PD with FFD-100 (I have one) and apply 100V of reverse bias.

P.3 Current noise spectrum

The measured dark noise voltage spectrum was converted to the equivalent current noise at the diode.

The measured transimpedance is ~1.2kV/A.
The reduction of the transimpedance above 100MHz has been seen as 165MHz is already at the edge of the bandwidth.
If we need more transimpedance at 165MHz, we should replace the diode with FFD-100 (I have one) and apply 100V of reverse bias.

P.4 Shot-noise intercept current

Shot-noise intercept current was measured with a white light from a light bulb.
This measurement suggests the shot-noise intercept current of 1mA, and transimpedance of 1.5kV/A.

Attachment 1: REFL165_response_130702.pdf
REFL165_response_130702.pdf REFL165_response_130702.pdf REFL165_response_130702.pdf REFL165_response_130702.pdf
  8803   Thu Jul 4 19:37:37 2013 KojiUpdateSUSNew SUS screen

Totally agree. The old suspension screen should be driven away.

  8815   Tue Jul 9 20:09:53 2013 KojiUpdateIOOWFS debugging

The low UGFs of the MC WFS servos made the MC insane thesedays:
The servos are too slow and we kept having significant misalignment left uncompensated.

I increased the total gain of the MC WFS from 0.01 to 0.4 (x40) to make the UGFs of the
WFS paths to ~2Hz. This was too much gain for the QPD path so the gains for the QPD paths
were reduced by a factor of 4 (x10 in total).

The script mcwfsup was also modified accordingly.

  8816   Tue Jul 9 23:27:17 2013 KojiSummaryLSCMICH: ITMX/Y <=> PRM/BS

The MICH actuation with PRM/BS was investigated again.

(ITMX -1 / ITMY +1) is equivalent to (PRM -0.267 and BS +0.50).


- PRMIsb was locked with REFL33I&AS55Q.

- Using the locking module in the LSC model, actuate ITMX (-1) and ITMY (+1) at 580.1Hz. Note that the notch filters in the MICH/PRCL servos were on.

- Look at the peak in the AS55Q spectrum. Tune the BS element in the output matrix of the lock-in to minimize the peak height.
=> The peak was minimized at BS = -0.50.

- Look at the peak in the REFL33I spectrum. Tune the PRM element in the output matrix of the lock-in to minimize the peak height.
=> The peak was minimized at PRM = +0.267

- These measurement leads to the conclusion mentioned above.

  8833   Fri Jul 12 00:12:41 2013 KojiUpdateLSCPRMI + Y arm trial

[Koji, Manasa, Annalisa]

I made several trials to scan the arm on the IR TEM00 resonance while the PRMI was held with REFL165I&Q.
It was so hectic to keep multiple systems running correctly. We talked about how it should be automated.
We'll gradually offload the switching works on scripts.

In a good alignment condition, when I swept on the resonance, everytime the PRMI lost the lock. It reacquired
once the arm passed the resonance.

Lately I got difficulty to acquire lock of the PRMI while the arm is waiting at its off resonance.
If I change the ALS offset I got a stable lock in a certain offset, and did not get in another offset
so there could be something systematic. (The arm was in between the carrier resonance and the next sideband (55MHz) resonance).

-----

Procedure

[Preparation]

- Run LSCoffset script.

- Misalign PRM. Lock and align the arms with ASS.

- Go into the tables. Align the oplevs for ETMX/Y, ITMX/Y, and BS. (Very important for alignment stability)

- Align PRMI and lock PRMI. Unlock once.

- Go into the BS/PRM table. Align the oplev for PRM.

[ALS]

- Misalign PRM by -0.2

- Find the beat note at around 50MHz by changing the Yarm SLOW control. Today the PSL SLOW was ~0.24, and the Yarm SLOW was -10981.

- Reset Phase Tracker History (Important)

- Engage Yarm ALS with FM5. Tested the sign of the servo by giving 0.01 or -0.01. In my case, the negative number worked fine.
  Gradually increase the gain up to -10. Turn on FM2/3/6/7/10.

- Use Filter module "C1ALS-OFFSETTER2" to give the ALS sweep. I used FM1 (30mHz LPF). Change the offset while looking at the IR TRY and POY11 error signal.

- Once the resonance is found, shift the beat note by giving +10 or -10 offset.

[PRMI]

- While the arm is kept off resonance, align PRM.

- Lock PRMI with REFL33I and AS55Q. Turn on PRM ASC.

- Once the stable lock is obtained, switch the input signals to REFL165I&Q. I used REF33I x1.0->REFL165I x0.8 and AS55Q x1.0 -> REFL165Q x0.5

[PRMI + one arm]

- Revert the ALS offset by 10 to bring the arm on the resonance the see what happens.

 

  8838   Fri Jul 12 13:15:43 2013 KojiUpdateISSRMS Noise from PMC Transmission

It would be better to measure the power spectrum density of the fluctuation.
The RMS does not tell enough information how the servo should be.
In deed, the power spctrum density gives you how much the RMS is in the entire or a specific frequency range.

  8843   Sun Jul 14 17:47:28 2013 KojiUpdateIOOMC WFS maintenance

Annalisa notified me that the MC autolocker could not keep the MC locked.

I found the initial alignment was not good and the MC was too much excited when the WFS kicked in.

There might have been the WFS offset issue due to the miscentering of the spots on the WFS diodes.

I used the usual procedure of the maintenance and it looked OK if I followed the switching procedure the mc autolocker suppoed to do.
http://nodus.ligo.caltech.edu:8080/40m/7452

I still could not get the autolocker running smoothly. I opened mcup script and compared what was the difference
between my manual sequence and what the script did. The only difference was the lines related to MCL.
It was still turning on the filter module. I checked the MCL path and found that the gain was not zero but 1.0.
So now the MCL gain is set to zero. This solved all the remaining issue.

  8846   Mon Jul 15 13:51:17 2013 KojiConfigurationendtable upgradeDAC at 1Y4-Max Output and Power Spectrum

We need the unit of the voltage power spectrum density to be V/sqrt(Hz).
Otherwise we don't understand anything / any number from the plot.

  8855   Tue Jul 16 10:16:23 2013 KojiUpdate Beatbox XARM whitening modified

The X arm whitening filters of the beatbox were modified.
Now we have about 10 times better floor level above 100Hz and ~3 better at 1Hz.


- The previous whitening was zero@1Hz, pole@10Hz, and the DC gain of the unity.
  When the Marconi signal (~30MHz -25dBm) was given to the beatbox (via ZFL-1000LN),
  the DC output of the beatbox was only 140mV (lame). This corresponded to 220 counts in
  the CDS.
(BTW the signals were calibrated by giving frequency deviation of 1kHz is applied at 125Hz.)

- If you compare the analog measurement of the beatbox output and what we see in the I phase signal,
  you can see that we were completely dominated by the ADC noise (attachment 2, blue and red).

- The new whitening is zero@5.2Hz, pole@159Hz, and the DC gain of 10.

- This improved the sensing noise by a factor of ten above 100Hz.

- We are stil llimited by the digitizing noise between 3Hz to 100Hz.
  We need steeper whitening like 2nd order from 1Hz to 100Hz. (and probably at DC too).
  Now the DC amplitude is about 1.4V (and 2200 counts in the CDS).
  So, it is interesting to see how the sensing limit changes by increasing
  the overall gain by a factor of 3, and have (zeros@1Hz & poles@10Hz)^2.

  This can be implemented on a proto-daughter board.

- By the way, the performance below 2Hz is now better than the analog one with the previous whitening.
  This improvement might have come from the replacement of the thick film resistors by thin-film resistors.
  (See the circuit diagram)


About the nominal power of the beatbox input.

- Marconi (-20dBm 30MHz) was directly connected to the beatbox. The RF output of -15dBm was observed at the delayline output.
- According to the beatbox schematic, the mixer LO and RF inputs were expected to be -9dBm and -19dBm.
- The nominal mixer LO level is supposed to be 7dBm. Therefore the nominal beatbox input should be -4dBm.

- Assuming 23dB gain of the preamp, the PD output is expected to be -27dBm.

- When the PD out is -27dBm, the RF mon is expected to be -5dBm. This is the level of the RF power expected to be seen in the control room.

- The output of the beatbox was measured as the function of the input to the preamp (before the beatbox input).
  With the nominal gain, we should have observed amplitude of ~170. And it is now 1700 because of the whitening modification.
 

Attachment 1: Beatbox_mod.pdf
Beatbox_mod.pdf
Attachment 2: ALS_whitening.pdf
ALS_whitening.pdf
Attachment 3: Beatbox_input_dependence.pdf
Beatbox_input_dependence.pdf
  8864   Wed Jul 17 22:49:37 2013 KojiUpdateGreen LockingALS Y whitening filter change

[Koji Annalisa]

We did the same mod of the beatbox for the Y arm too. See
http://nodus.ligo.caltech.edu:8080/40m/8855

  8865   Wed Jul 17 22:51:50 2013 KojiUpdateGreen LockingALS Y performance with the new whitening filter

[Manasa Koji]

Summary:
The new whitening filters improved the out-of-loop ALS stability of the Y arm down to 300Hz (20pm_rms in displacement).


- After modifying the whitening filters, the out-of-loop stability of the arms were tested with the IR PDH signals.

- The X arm showed non-stationarity and it made the ALS servo frequenctly fell out of lock.

- For now we decided to use the Y arm for the PRMI+one arm trial.

- The performance of the ALS was tested with several measurements. (attachment 1)

Cyan: Stability of the beatnote frequency with the MC and the arm freely running. The RMS of the day was ~6MHz.

Blue: Sensing limit of the beat box was tested by giving a signal from Marconi. The same amplitude as the X arm beat was given as the test signal.
This yielded the DC output of ~1200 counts.

Green: Out-of-loop estimation of the beatbox performance. This beat note stability was measured by controlling the arm with the IR PDH signal.
Assuming the PDH signal has better SNR than the beat signal, this gives us the out-of-loop estimation of the stability below 150Hz, which is the
unity gain frequency of the ALS loop.
Above 150Hz the loop does not force this noise to the suspension. Just the noise is injected via a residual control gain (<1).

Black: In-loop evaluation of the ALS loop. This becomes the left over noise for the true stability of the arm (for the IR beam).

Red: The arm was brought to the IR resonance using the ALS offset. The out-of-loop stability was evaluated by the IR PDH signal.
This indeed agreed with the evaluation with the other out-of-loop evaluation above (Green) below 150Hz.


Attachment 2 shows the time series data to show how the arm is brought to the resonance.
1 count of the offset corresponds to ~20kHz. So the arm started from 200kHz away from the resonance
and brought to the middle of the resonance.

(Manasa downloaded the 2k sampled data so that we can use this for presentations.)

Attachment 1: ALS_Y_130717.pdf
ALS_Y_130717.pdf
Attachment 2: ALS_Y2_StripTool.png
ALS_Y2_StripTool.png
  8867   Thu Jul 18 02:21:41 2013 KojiUpdateLSCPRMI+Y arm ALS success!

[Koji, Jenne, Manasa, Annalisa, Rana, Nic]

PRMI locked using 3f signals and Y arm brought to resonance using ALS


<<Procedure>>

Preparation:

- After we checked the functionarity of the Yarm ALS, both arms were locked with the IR, and aligned by ASS.

- Disengaged the LSC feedback. Approximately aligned the PRM.

- Recorded the current alignment biases. Turned off all of the oplevs.

- Went into the lab, aligned all of the oplevs on the QPDs (except for the SRM).

- Check the locking of the PRMI.

- Once it is locked, go into the lab again and align the POP QPD.

- Check everything of the PRMI LSC/ASC works.

- Misalign PRM by 0.2

- Lock the arm again. Run ASS again.

- Miaslign ETMX.

ALS:

- Lock the Xarm with green. Adjust the beat freq between 30-50MHz.

- Reset Phase Tracker history.

- Check if there is any offset for the ALS. If there is, adjust it to zero.

- Stabilize the arm with the ALS. We should check the sign of the servo before it is cranked up to the nominal.

- Confirm if the offset FM has LPF (30mHz LPF).

- Run excastep for the ALS offset until we find the TEM00 resonance of the IR

- Record the offset at the resonance.

- Step back by 5 count (=100kHz)

PRMI+ALS:

- Started from the offset of -5.

- Aligned the PRM and the PRMI was locked by REFL165I(x0.8)nadQ(x0.2).

- PRM ASC engaged

- Moved the offset to -4 by ezcastep C1:ALS-OFFSETTER2_OFFSET +0.01,100 -s 0.1

- Moved to -3, -2, -1.5, -1. During the sweep PRCL/MICH gain was tweaked so that the gain is reduced.
  Nominal locking gain was PRCL x+2.5/MICH -30 . During the sweep they were +2.2 / -12
  PRCL FM2/4/5 ON, Later FM3/6 turned on and no problem.

- Moved to -0.9, .... , and finally to 0.


NEXT STEP

- Automation of the PRMI+one arm

- PRMI locking with BS/PRM

- Better sensing matrix

- PRMI+two arms

- Use of the DC signals form the transmission monitors. (High power /low power transmon).

 

 

Attachment 1: Screenshot-Untitled_Window1.png
Screenshot-Untitled_Window1.png
Attachment 2: PRMI_Yarm.pdf
PRMI_Yarm.pdf
  8872   Thu Jul 18 16:30:08 2013 KojiUpdateLSCPRMI+Y arm ALS Sensing Matrices

Hmm. I agree that something was funny.
Let's take the matrix without the arms and confirm the measurement is correct.

  8881   Fri Jul 19 14:04:24 2013 KojiUpdateCDSCDS FE not happy

daqd was restarted.


- tried telnet fb 8088 on rossa => same error as manasa had

- tried telnet fb 8087 on rossa => same result

- sshed into fb ssh fb

- tried to find daqpd by ps -def | grep daqd => not found

- looked at wiki https://wiki-40m.ligo.caltech.edu/New_Computer_Restart_Procedures?highlight=%28daqd%29

- the wiki page suggested the following command to run daqd /opt/rtcds/caltech/c1/target/fb/daqd -c ./daqdrc &

- ran ps -def | grep nds => already exist. Left untouched.

- Left fb.

- tried telnet fb 8087 on rossa => now it works

  8882   Fri Jul 19 22:35:06 2013 KojiSummaryLSCVarious Arm signal (Yarm)

The StripTool plot attached below shows various arm signals measured with the Y arm cavity swept using ALS.

Yellow: TRY

Blue: ALS additive OFFSET to the error signal

Red: Raw PDH error signal (POY11I)

Purple: Linearized PDH error (POY11/TRY)

Green: 1/Sqrt(TRY)-5 (No normalization)

Inverse Sqrt of the TRY had been implemented when this LSC controller was first coded.
It is confirmed that the calculation is working correctly.

Attachment 1: various_arm_signal.png
various_arm_signal.png
  8885   Fri Jul 19 23:35:52 2013 KojiSummaryLSCTRY DC locking

The Y arm was locked with the TRY DC signal.

The handing off process is too complicated because there is no path from ALS to the LSC error.


 The TRY DC error signal & the gain determination

- The error signal was produced by the operation 1/SQRT(TRY) - OFFSET. The initial offset was -5.

- The sign of the TRY DC error signal depends on which side of the resonance the arm is.
  By looking at the strip chart, I determined that the sign is opposite of the ALS.
  The ALS had the gain of -25, so the TRY control gain was to be positive.

- From the strip chart on the previous entry , the slope difference between the PDH error and the TRY DC error was x500.
  The arm control with POY11 PDH had the gain of 0.2. So the target gain for the TRY DC was determined to be +100.

Handing off

- The arm was stabilized by ALS. The ALS gain was -25 with FM2/3/5/6/7/10

- YARM configuration: no trigger / no FM trigger / gain =+0 / FM5 ON / OFFSET -5

- Start handing off:
  YARM: Turned up the gain to +50

- ALS: Turned off FM6/7

- YARM: Turned on FM6/7

- ALS: Turned off FM2

- YARM: Turned on FM4

- ALS: Turned off FM3/10

- YARM: Turned on FM2/3/8/9 ON

- ALS: Reduced the gain to -15

- YARM: Increased the gain to +70

- ALS: Reduced the gain to 0

- YARM: Increased the gain to +100

HANDING OFF - DONE

Changing the offset

The offset of -5 gave the TRY of <0.1.

The detuning was reduced by giving the offset of -4. TRY went up to ~.1

The offset of -3 made TRY 0.13

The offset of -2 made TRY 0.25

The offset of -1.5 made TRY 0.4. And the arm could not be held by this error signal anymore.

 

 

Attachment 1: TRY_locking.png
TRY_locking.png
  8889   Mon Jul 22 16:30:31 2013 KojiUpdateGeneralVent preparation

[Annalisa, Manasa, Jenne, Koji]

We are working on the vent preparation.

First of all, there was no light in the interferometer.
Obviously there were lots of IFO activity in the weekend. Some were elogged, some were not.
Annalisa took her responsibility to restore the alignment and the arms recovered their flashes.

The odd thing was that the ASS got instable after we turned down the TRY PD gain from +20dB to +10dB (0dB original).
We increased the TRY gain by factor of 10 (that's the "10dB" of this PDA520. See the spec sheet) to compensate this change.
This made the ASS instable. Anyway we reduced the gain of TRY PD to 0dB. This restored the ASS.

Jenne took some more data for the QPD spectrum calibration.

Link to the vent plan

  8895   Mon Jul 22 22:06:18 2013 KojiUpdateCDSFE Web view was fixed

FE Web view was broken for a long time. It was fixed now.

The problem was that path names were not fixed when we moved the models from the old local place to the SVN structure.

The auto updating script (/cvs/cds/rtcds/caltech/c1/scripts/AutoUpdate/update_webview.cron) is running on Mafalda.

Link to the web view: https://nodus.ligo.caltech.edu:30889/FE/

  8896   Tue Jul 23 00:51:46 2013 KojiUpdateendtable upgradeEnd table picture

The spot on the IPANG QPD was checked. The spot is higher than the center and South side of the lens.
Some photos are found below.

The spot on the IPANG steering mirrors in the ETMY chamber was also checked.
It is clipped at the top of the steering mirror. (See attachment 4)
So basically the spot is about 1" above the center of the mirror.

Attachment 1: P7224222.JPG
P7224222.JPG
Attachment 2: P7224223.JPG
P7224223.JPG
Attachment 3: P7224224.JPG
P7224224.JPG
Attachment 4: P7224238.JPG
P7224238.JPG
  8898   Tue Jul 23 03:10:57 2013 KojiUpdateGeneralVent preparation - In progress

Centering of the oplev beams: done

Recording the OSEM values: done

Attachment 1: OSEM_RECORD.png
OSEM_RECORD.png
Attachment 2: OPLEVS.png
OPLEVS.png
  8901   Tue Jul 23 04:22:03 2013 KojiUpdateGeneralVent preparation - In progress

[Koji Jenne]

Low power MC locking

- Rotated HWP right after the laser

- Put a knife edge beam dump at the output of the PBS after the HWP.

- Replaced the PO mirror for the MC refl by an HR mirror.

- PMC:
Input offset from 0 to 0.29
Servo Gain from 10 to 30
=> Transmission 0.84 (1.2W at the MC input) to 0.069 (100mW)

- MC:

VCO Gain from 25 to 31
MC REFL: Unlocked 3.6 Locked 0.38-0.40

  8905   Tue Jul 23 13:29:58 2013 KojiSummaryGeneral 

record of the initial state

Attachment 1: initial_state_130723.png
initial_state_130723.png
  8906   Tue Jul 23 13:55:08 2013 KojiUpdateIOOMC manually aligned

The MC was manually aligned. The spot positions were measured and it is consistent with the measurements done yesterday.

Attachment 1: MCalignment.png
MCalignment.png
Attachment 2: MCspot.png
MCspot.png
  8908   Tue Jul 23 16:39:31 2013 KojiUpdateGeneralFull IFO alignment recovered

[Annnalisa Koji]

Full alignment of the IFO was recovered. The arms were locked with the green beams first, and then locked with the IR.

In order to use the ASS with lower power, C1:LSC-OUTPUT_MTRX_9_6 and C1:LSC-OUTPUT_MTRX_10_7 were reduced to 0.05.
This compensates the gain imbalance between TRX/Y siganls and the A2L component in the arm feedback signals.

Despite the IFO was aligned, we don't touch the OPLEVs and green beams to the vented IFO.

Attachment 1: alignment.png
alignment.png
  8913   Tue Jul 23 21:32:43 2013 KojiUpdateIOOFound the cause of mysterious MC motion

Thesedays we were continuously annoyed by unELOGGED activities of the interferometer.

MC2 LOCKIN was left on and has continuously injected frequency noise and beam pointing modulation
during all of the comissioning / vent preparation.

C1:SUS-MC2_LOCKIN2_OSC_FREQ was 0.075
C1:SUS-MC2_LOCKIN2_OSC_CLKGAIN was 99

For more than a week ago we noticed that the curve of the MC WFS stripchart suddenly got THICKER.
MC WFS, arm transmission, beam pointing... everything was modulated.
It was not WFS instability, and it was not the cavity mirrors.

Today I made the investigation and finally tracked down the cause of this issue to be on MC2 suspension.
Then it was found that this LOCKIN was ON.

There is no direct record of this lockin in the frame files.
From the recorded channel "C1:IOO-WFS2-YAW_OUT16" (which is the trace on the StripTool chart on the wall)
It was turned on at July 10th, 2:00UTC (July 9th, 7PM PDT)

  8918   Wed Jul 24 15:07:54 2013 KojiUpdateSUSSR2 flipped

After the first flipping, X/Y arms were aligned and locked. Then the ASS aligned the arms.

ELOG V3.1.3-