ND filter ND3 (which is at the REFL port to the REFL OSA) is removed. Don't forget to put it back when you restore PRM!!!

AS55Q and AS55I signals. AS55Q is around zero while AS55I has a large offset which is about the signal amplitude. It is likely because of the RAM?

keiko, kiwamu

[Keiko / Kiwamu]

 Update on the MICH characterization:

• The OSAs weren't so great because the 11 MHz sidebands were covered by the carrier's tail
  • It seemed that the frequency resolution depended on the mode matching. We will try improving the mode matching tomorrow.
• The noise budget looked very bad
  • There were huge peaks at 1 Hz, 3 Hz, 16.5 Hz and 23 Hz. Something is crazy in the vertex suspensions.
  • Keiko will post the calibrated noise budget.
• The MICH response at AS55Q was measured and we will calibrate it into watts / meter.

 On the right figure, you see the non-zero operation points even when RAM mod index = 0. Apparently they come from non-zero loss of the model.  (Each mirror of 50ppm loss was assumed).

 As par Kiwamu's request, RF filters for POP22 and POP110 were installed. They are not really nice. We need to replace it with more fancy electronics.
More to come later.

The RF separator installed comprises of the Minicircuits filters cascaded as in the figure below.
This has one input and 4 output ports for 11, 22, 30-60, and 110MHz signal.
As seen in this entry #6167, we have 22 and 110MHz signals together with 11, 44, 66MHz signals.
They may be demodulated via a harmonic characteristic of the mixers. (Remeber mixers are not multipliers.)

 Of course the big concern is the impedance matching for those signals as usual.
The 2nd attachment shows measured impedance of the circuits with all of the ports terminated.
From the complex impedance, we can calculate the reflection coefficient. The 44 and 110MHz
components look correctly matched while the others seems largely reflected.
This certainly is not a nice situation, as the reflection can make the amplifier next to the PD unhappy
(although the reflected power is tiny in our case).

In our case more eminent problem is that the amplitude of the 22MHz signal can vary depending on the cable length by
factor of 10 in amplitude. (c.f. VSWR on the 2nd attachment.)

The transmission to each port was measured. The separation of the signals looks good. But the attenuation of the
targetted signals (i.e. insertion losses) are qulitatively consistent with the impedance. Again these losses are depend
on the cable length.

 I swap an OSA at PSL and OSA at REFL. It was because the PSL-OSA had a better resolution, so we place this better one at REFL. The ND filter (ND3) which was on the way to REFL OSA was replaced by two BSs, because it was producing dirty multiple spots after transmitting.

 This is the calibrated MICH noise budget on Mar 5. There was a sharp peak at 1Hz and a blob on 3 Hz. The demod phase was adjusted for AS55Q.

Just a quick report on the REFL OSA.

The attached plot below shows the raw signal from the REFL OSA which Keiko installed in this afternoon.

When the data was taken the beam on the REFL OSA was a direct reflection from PRM with the rest of the suspended mirrors misaligned.

One of the upper and lower 11 MHz sidebands is resolved (it is shown at 0.12 sec in the plot) while the other one is still covered by the carrier tail.

The 55 MHz upper and lower sidebands are well resolved (they are at 0.06 and 0.2 sec in the plot).

One of the oscilloscopes monitoring the OSA signals in the control room has a USB interface so that we can record the data into a USB flash memory and plot it like this.

I'm puzzled why the 11MHz peak can be such high considering 1.7~2 times smaller the modulation depth.

This is the MICH noise budget on 6th March. 1Hz peak got a bit better as the BS sus control gain was increased.

I was also wondering about the same thing, comparing with what Mirko obtained before with the same OSA ( #5519).

 kiwamu, keiko

We measure the REFL OSA spectrum when (1) direct reflection from the PRM (2) CR lock at PRC (3) SB lock at PRC. When CR lock, both SBs are reflected from the PRC and when SB lock (ref line), some SB is sucked by PRM and looked lower than the other two lines.

Here is the recent two noise budgets of MICH, with the old measurement by Jenne. The most latest Mar 6 data is quite close to the old data, even better around 20-30 Hz. Probably some scattering source was improved?

[Keiko / Kiwamu]

 Some updates on the locking activity:

• Started summarizing the data of the Michelson lock in a wiki page:
  • https://wiki-40m.ligo.caltech.edu/Interferometer_Characterization/Michelson_Noise_Budget
  • Some careful analysis of the OSA signals are missing
    • Besides the analysis we need to work on the mode matching to get a better resolution as Mirko achieved.
• Gradually moving on to the PRMI lock
  • The lock stays for reasonably a long time (~20 min or more)
  • POP22/110 demod signals seemed just ADC noise.
  • A first noise budget is in process
    • The glitches make the noise level worse above 40 Hz or so in both the MICH and PRCL budgets.
  • Sensing matrix will be measured tomorrow
  • The data will be also summarized in a wiki page

We tried to measure the sensing matrix for MICH and PRCL last night. They look too much mixed as we expect... the matrix may be posted later. We suspect the IX and IY of the MICH excitation is not balanced very well, although Kiwamu adjusted that about two weeks ago, and it is mixing the dof. We'll try to balance it again, ans see the matrix. 

Keiko, Kiwamu

ITMX and ITMY balance for the MICH excitation (lockin) is adjusted again. Now it's ITMx = -0.992, ITMy = 1 for MICH (lockin output matrix values).

RA: what were the old values? Does this change make any difference for the signal mixing noticed before?

 I calculated the DRMI RAM LSC matrix with RAM and the operation point offsets.

• configuration: C1 DRMI
• RAM is added by an Mach-Zehnder ifo placed before the PRM
• demodulation phases are optimised for each DoF
• the operation points offset from the PDH signals are calculated and added to the optical configuration as mirror position offsets
• Then the matrix is calculated with the offsets and the RAM
• The set of the scrips are found as RAMmatrix.m, normMAT.m, newGetMAT.m,  on CVS/ifomodeling/40m/fullIFO_Optickle. They are a bit messy scripts at this moment.

Results:

(1) No RAM LSC matrix

(2) With 1% RAM mod index of PM (normalised by (1) )

(3) With 5% RAM mod index of PM (normalised by (1) )

Adding some more results with more realistic RAM level assumption.

(4) With 0.1% RAM mod index of PM (normalized by (1) )

(5) With 0.5% RAM mod index of  PM (normalized by (1) )

The punch line is -- the sensing matrix still looks strange in the PRMI configuration.

I have been measuring the sensing matrix of the PRMI configuration because it didn't make sense (#6283).

One strange thing I have noticed before was that all the I-phase signals showed a weird behavior -- they fluctuate too much in time series.

Tonight I measured the sensing matrix again but this time I recorded them as a function of time using the realtime LOCKINs in the LSC front end.

The attached plots are the responses (optical gains) of PRCL and MICH in watts / meter at various sensors in time series.

I will explain some more details about how I measured and calibrated the data in another elog entry.

Here I describe the measurement of the sensing matrix.

Motivations

  There were two reasons why I have been measuring the sensing matrix :

1.  I wanted to know how much each element in the sensing matrix drifted as a function of time because the sensing matrix didn't agree with what Optickle predicted (#6283).
2.  I needed to estimate the MICH responses in the 3f demodulated signals, so that I can decide which 3f signal I should use for holding MICH.

 I will report #2 later because it needs another careful noise estimation.

Measurement

 In order to measure the sensing matrix, the basic steps are something like this:

1. Excite one of the DOF at a certain frequency, where a notch filter is applied in the LSC servos so that the servos won't suppress the excitation signal.
2. Demodulate the LSC signals (e.g. C1:LSC-REFL11_I_ERR and etc.,) by the realtime LOCKINs (#6152) at the same frequency.
3. Calibrate the obtained LOCKIN outputs to watts/meter.

LOCKIN detection

• The LOCKIN oscillator excites ITMs differentially
  • In order to purely excites the MICH DOF, the actuation coefficients were precisely adjusted (#6398).
  • Currently ITMY has a gain of 1, and ITMX has a gain of -0.992 for the pure MICH excitation. Those numbers were put in the output matrix of the LOCKIN oscillator.
• The demodulation phase of the LOCKIN system was adjusted to be -22 deg at the digital phase rotator.
  • This number maximizes the in-phase signals while the quadrature-phase signals give almost zero.
  • This number was adjusted when the simple MICH configuration was applied.
• In the demodulations, the LO signals have amplitude of 100 counts to just make the demodulated signals readable numbers.

Calibration of the LOCKINs

Calibration of the responses to watts/meter

Settings and parameters

•  LSC RF demodulation phases
  
  •  AS55 = 17.05 deg (minimizing the PRCL sensitivity in the Q-phase)
  •  REFL11 = -41.05 deg (maximizing the PRCL sensitivity in the I-phase)
  • REFL33 = -25.85 deg (maximizing the PRCL sensitivity in the I-phase)
  • REFL55 = 4 deg (maximizing the PRCL sensitivity in the I-phase)
  • REFL165 = 39 deg (random number)
•  Whitening filters
  • AS55 = 30 dB
  • REFL11 = 0 dB
  • REFL33 = 42 dB
  • REFL55 = 30 dB
  • REFL165 = 45 dB
• MICH servo
  • AS55_Q for the sensor
  • G = -5 in the digital gain
  • FM2, FM3, FM5 and FM9 actiavted
  • UGF ~ 100 Hz
  • Feedback to ITMs differentially
• PRCL servo
  • REFL33_I for the sensor
  • G = 1 in the digital gain
  • FM2, FM3, FM4, FM5 and FM9 activated
  • UGF ~ 100 Hz
  • Feedback to PRM

Next steps:

• Compare the obtained sensing matrix with an Optickle model. Particularly I am interested in the absolute strengths in watts/meter
• Noise estimation of the REFL33_Q as a MICH sensor to see if this sensor is usable for holding MICH.

A feasibility study of the REFL33Q as a MICH sensor was coarsely performed from the point view of the noise performance.

The answer is that :

  the REFL33Q can be BARELY used as a MICH sensor in the PRMI configuration, but the noise level will be at only sub-nano meter level.

  Tonight I will try to use the REFL33Q to control the MICH DOF to see what happens.

(Background)

(Noise analysis)

  I did a coarse noise analysis for the REFL33Q signal as shown in the attached plot below while making some assumptions as follows.

•  Optical gain for MICH = 0.8  W/m (#6403)
  • In the plot below, I plotted a unsuppressed MICH motion which had been measured the other day with a different sensor. This is for a comparison.
•  Shot noise due to DC light on the REFL33 photo diode
  •  With a power of 5.0 mW (#6355)
  • Assume that the responsivity is 0.75 A/W, this DC light creates the shot noise in the photo current at a level of 35 pA/sqrtHz.
  • Then I estimated the contribution of this shot noise in terms of the MICH displacement by calibrating the number with the optical gain and responsivity.
  • It is estimated to be at 60 pm/sqrtHz
• Dark current
  • I assumed that the dark current is 0.52 mA. (see the wiki)
  • In the same manner as that for the shot noise, the dark current is estimated to be at 20 pm/sqrtHz in terms of the displacement
• Whitening filter input referred noise
  • I assumed that it is flat with a level of 54 nV/sqrtHz based on a rough measurement by looking at the spectrum of the LSC input signals.
  • The contribution was estimated by applying some gain corrections from the conversion efficiency of the demod board, transimpedance gain, responsivity and the optical gain.
  • This noise is currently the limiting factor over a frequency range from DC to 1 kHz.
• ADC noise
  • I did the same thing as that for the whitening filter noise.
  • I assumed the noise level is at 6 uV/sqrtHz and it is flat (I know this not true particularly at mHz region the noise becomes bigger by some factors)
  • Then I applied the transfer function of the whitening filter to roll off the noise above 15 Hz.

(Some thoughts)

•   Obviously the limiting noises are that of ADC and the whitening filter.
  • These noise can be easily mitigated by installing an RF amplifier to amplify the RF signals from the REFL33Q RFPD.
  • Therefore this is not the real issue
• The real issue is that the shot noise is already at a level of 60 pm/sqrtHz, and we can't suppress the MICH motion less than that.
  • In order to decrease it, one possibility is to increase the modulation depth. But it is already at the maximum.
  • If the REFL165 RFPD is healthy, it is supposed to give us a bigger MICH signal. But it didn't look healthy ... (#6403)

 I tried the REFL33Q for controlling MICH in the PRMI configuration (#6407)

The result was --

 It was barely able to lock MICH in a short moment but didn't stay locked for more than 10 sec. Not good.

(Tricks)

A correction on the previous elog about the REFL33Q noise:

In the last post, I showed that SRCL element in the MICH sensor (AS55I-mich) is chaned 1% due to RAM.

Here I calculated how is this 1% residual in MICH sensor (AS55 I-mich) shown in MICH sensitivity. The senario is:

(1) we assume we are canceling SRCL in MICH by feed forward first (original matrix (2,3) element).

(2) SRCL in MICH (matrix(2,3) is changed 1% due to RAM, but you keep the same feed forward with the same feedforward gain

(3) You get 1% SRCL residual motion in MICH sensor. This motion depends on how SRCL is quiet/loud. The assumed level is

Pollution level = SRCL shot noise level in SRCL sensor  x  SRCL closed loop TF  x  1% residual .... the following plot.

AS sensor = AS55I-mich  --- SN level 2.4e-11 W/rtHz ------- MICH SN level 6e-17 m/rtHz

SRCL sensor = AS55 I-SRCL --- SN level 2e-11 W/rtHz ---  SRCL SN level 5e-14 m/rtHz

This is the simulated signals to compare with the original post #6403

Kiwamu and Koji

The target is to realize DRMI or PRMI + one arm with ALS.

The focus of the night is to achive stable lock of the PRMI (SB resonant) with 3f signals.
Particularly, REFL165 is back now, we are aiming to see if any of the 165 signals is useful.

We made a comparison between  REFL33Q/REFL165Q/AS55Q to find any good source of MICH.
However, none of them showed a reasonable shape of the spectra. They don't have reasonable coherence between them.

Nonetheless, we have tried to lock the IFO with those REFL signals. But any of them were useful to keep the PRMI (SB resonant).
The only kind of stable signal for MICH was AS55Q as we could keep the PRMI locked.

Yesterday I and Kiwamu connected two amplifiers (mini-circuit, ZFL-1000LNB+) for POP22/110. Dataviewer can see some signals. I'll test the signal levels and freq components before the rack just in case. [Kiwamu, Keiko]

Adding two amplifiers on POP22/110, I checked the signals going to the dmod board of 22 and 110.

The signal flows: Photodetector of POP --> Amp1 --> Amp2 --> RF splotter --> bandpass filter for 22MHz / 110MHz --> 22MHz / 110MHz demod board.

 Here is the picture of RF spectrum just after the bandpass filter of 22MHz going to the 22MHz demod board. The signal peak at 22MHz is about -40dBm. There is a structure slightly lower than 22MHz.

The below is the RF spectrum for 110MHz branch. The peak at 110MHz is about -15dBm. The peak on the left of 110MHz is 66MHz peak.

I was trying to make the DRMI lock more robust.

Increasing the gains of the oplev on SRM helped a lot, but the lock is still not solid enough for measurements.

According to some line injection tests, the SRCL and MICH signals show up in AS55Q with almost the same amplitudes.

I tried to diagonalize the input matrix (particularly MICH-SRCL in AS55) based on the result of the line injection tests, but I ran out the time.

Work continues.

I have measured the sensing matrix of the DRMI although the lock still doesn't stay for a long time.

As for the noise budget, it looks very tough as there are more glitches than that in the PRMI.

In this weekend I will take some more trials in the DRMI lock until I am satisfied.

 I extended my RAM script from DRMI (3DoF) to the full IFO (5DoF).

Again, it calculates the operation point offsets for each DoF from the opt model with RAM. Then the position offsets are added to the model, and calculates the LSC matrix. RAM level is assumed as 0.1% of the PM modulation level, as usual, and lossless for a simple model.

Original matrix without RAM:

REFL f1 : 1.000000    0.000000    0.000008    -0.000005    0.000003 

  AS f2 : 0.000001    1.000000    0.000005    -0.003523    -0.000001 

 POP f1 : -3956.958708    -0.000183    1.000000    0.019064    0.000055 

 POP f2 : -32.766392    -0.154433    -0.072624    1.000000    0.024289 

 POP f2 : 922.415913    -0.006625    1.488912    0.042962    1.000000 

(MICH and SRCL uses the same sensor, with optimised demodulation phase for each DoF.) 

Operation position offsets are:

PRCL   -3.9125e-11 m

SRCL    9.1250e-12 m

CARM  5.0000e-15 m  

and no position offsets for DARM and MICH (because they are differential sensor and not affected by RAM offsets).

Resulting matrix with RAM + RAM offsets, normalised by the original matrix:  

REFL f1 : 0.001663    -0.000000    0.003519    0.000005    -0.000003 

  AS f2 : 0.000004    0.514424    0.000004    -0.001676    -0.000001 

 POP f1 : 7.140984    -0.001205    15.051807    0.019254    0.000417 

 POP f2 : 0.029112    -0.319792    0.042583    1.000460    0.024298 

 POP f2 : -0.310318    -0.014385    -1.761519    0.043005    0.999819 

As you can see in the second matrix, the CARM and DARM rows are completely destroyed by the RAM offsets! The signals are half reduced in the DARM case, so the mixture between DARM and MICH are about 50% degraded.

 I also would like to extend this script to use the DC readout, but don't know how to calculate the postion offset for AS_DC because the error signal is not zero-crossing for AS_DC anymore. Do you have any suggestions for me?

 I don't think I understand the question. AS_DC should not have a zero crossing, correct?

 That's right. I calculate the offset of the operation point (when you have RAM) from the zero-crossing point of the PDH signals. I don't know how to do that for AS_DC, because it doesn't cross zero anymore anytime.

I add a flow-chart drawing what the scripts do and how the scripts calculate the LSC matrix.

(1) First, you calculate the LSC matrix WITHOUT RAM or anything, just for a reference. This is the first matrix shown in the quoted post.

(2) The script calculates the LSC matrix with RAM. Also, the heterodyne signals for all 5 DoF are calculated. The signals have offsets due to the RAM effect. The operating position offsets are saved for the next round.

(3) The script calculates the LSC matrix again, with RAM plus the offset of the operation points. The matrix is shown in the last part of the quoted post.

Now I am going to check (A) LSC matrices (matrix 2, the second matrix of above chart) with different RAM levels (B) Are pos-offsets degrade the CARM and DARM so much (See, the quated result below), is that true?

Oops, Yesterday's results for DARM was wrong!

I got more convincing results now. 

> (B) Are pos-offsets degrade the CARM and DARM so much (See, the quoted result below), is that true? 

• CARM got a small position offset which degrades CARM signal 2 orders of mag (still the biggest signal in the sensor, though).
• DARM was not so bad, and probably the change of the DoF mixture is mostly not changed.
• Matrices don't change only with 1e-4 RAM. It changes with position offsets.
• I'll see how the matrix changes without position offsets but only with RAM effects, changing RAM levels.
• Again, above is C1 configuration, 1e-4 RAM level of PM level.

Koji and Jamie suggested me to include the coupling between DoFs when I calculate the last matrix. So far, I just add all the pos-offsets of 5 DoFs and re-calculate the matrix again. However, once I add one DoF pos-offset, it could already change the LSC matrix therefore different pos-offset to the other four DoF, we must iterate this process until we get the equilibrium pos-offsets for 5 DoFs.

I also noticed an error in the optical configuration file. AM mod levels were smaller than that supposed to be because of the hald power going through the AM-EOMs in the MZI paths. Also I have put PM-Mods in the MZT path which gives the smaller mod indexes. So, smaller mod levels were applied both for PM and AM. As PM-AM ratio is still kept in this, so the matrices were not very wrong, I assume. I'll modify that and post the results again.

 I'm still wondering whether iteration version or simple version is closer approximation to the real situation. Sorry for few explanations here. I will try to present those on Friday.

Anyway, here is the results for both:

%*.*.*. Original matrix w/o RAM .*.*.*

REFL f1 : 1.000000        0.000000    -0.000003    -0.000005    0.000007 

  AS f2 : 0.000002        1.000000    0.000009    -0.003522    -0.000002 

 POP f1 : -3954.521443    -0.000965    1.000000    0.019081    -0.000152 

 POP f2 : -32.770726    -0.154433    -0.072594    1.000000    0.024284 

 POP f2 : 922.393978    -0.006608    1.488319    0.042948    1.000000 

*** Iteration *** 

%*.*.*. Resulting matrix w/ RAM .*.*.*

REFL f1 : 0.039125    -0.000000    0.003665       0.000005    -0.000007 

  AS f2 : 0.000010    1.000431    0.000009       -0.003500    -0.000002 

 POP f1 : 156.420221    -0.000246    15.586838    0.019406    -0.000154 

 POP f2 : 1.255806    -0.154275    0.047313       1.000008    0.024285 

 POP f2 : -34.814720    -0.006600    -1.884850    0.042950    1.000000 

Offsets converged to:

PRCL =  2.1e-15, MICH = 1.1e-17, SRCL = -3.8e-15, CARM = 2.2e-16, DARM = 0 

(POP CARMs became so much smaller compared with the other matrix below, because the offsets are added al of 5 DoFsl at once here.)

*** no iteration, offsets added for each DoF separately ***

REFL f1 : 0.020611        -0.000000    0.003600    0.000005    -0.000007 

AS f2   : 0.000002        1.000000    0.000009    -0.003522    -0.000002 

POP f1  : 1842.776419    -0.000198    21.533358    0.019404    -0.000132 

POP f2  : -32.700639    -0.153095    -0.072481    0.999995    0.024360 

 POP f2 : 922.393862    -0.006435    1.488298    0.042949    0.999982 

Added offsets:

PRCL =  7.5e-15, MICH = 6.25e-16, SRCL = -1.4e-14, CARM = 4.5e-16, DARM = 0

* So far, I used to add all the offsets at once. This time I add CARM and get the CARM row, add PRCL and get the PRCL row... and so on.

I 

[Jenne / Kiwamu]

 We have installed a broad band PD in the AS path in order to monitor the 110 MHz signal associated with the SRC.

The PD is currently connected to the POP110 demodulation board and it seems working fine.

I know this is confusing but right now the signal appears as "POP110" in the LSC front end model.

• Installed a 50% BS at the AS path
  
  • The AS beam is split to two path - one goes to AS55 and the other goes to the OSA.
  • The new BS is installed on the way of the OSA branch therefore AS55 isn't affected by the new BS.
• Installed a PDA10A
  
  • This is a silicon diode with a bandwidth of 150 MHz, and is fast enough to detect the 110 MHz signals.
  • The 110 MHz signal seems going up to approximately -40 dBm according to a coarse measurement with an RF spectrum analyzer.
  • Also a SMA-style high pass filter, HPF-100, was attached to the output to cut off unnecessary sidebands (e.g. 11, 22 MHz and etc.)
• Put a long BNC cable, which goes from the PD to LSC rack.
  • The end of the cable at the LSC rack was directly connected to the POP110 demod board.
  • The actual POP110 signal path is currently terminated by a 50 Ohm load and therefore this signal  is unavailable.
• Adjustment of the demodulation phase
  • The demod phase was adjusted to be 7 deg in the EPICS screen. This phase minimize the Q-signal.
  • Locking PRMI with sidebands resonating makes the AS110 signal ~ a few counts and this level is still noticeable.
  • Perhaps we may need to put an RF amplifier to get the signal bigger.

 I tried locking the DRMI to the signal-extraction condition with the new trigger by AS110.

A first thing I tried was : flipping the control sign of the SRCL while keeping the same control setups for the PRCL and MICH.

Occasionally the DRMI was "sort of" locked and hence I believe this setup must be a good starting point.

As a next step I will try some different gains and demodulation phase to make it more lockable.

(Time series)

• REFL33I => PRCL  G = -0.2
• AS55Q => MICH    G = -6
• AS55I => SRCL     G = 1   (G = -50 for the signal recycling condition)
• AS55 demod phase = 17 deg

I didn't understand how CARM can be decreased 2 orderes of magnitude and PRCL can be INCREASED by such small offsets (see the matrix quoted).

Apparently it was because of an optical-spring ish effect from the "detuning" (which is actually RAM position offsets). I put two plots which are CARM and PRCL tranfer functions to REFL f1 or POP f1, when there is a slight PRCL offset (0, 1e-14m, and 1e-15m cases are plotted). Looking at these plots, it was not a good idea to calculate the LSC matrix in DC because they are affected by this detuning a lot. I'll try f = 150 Hz for the matrix.

It wasn't a dream or illusion -- I was locking the DRMI to the right condition last Wednesday (#6489).

Here is a snap shot of the AS-OSA signal taken today when the DRMI was locked with the same control settings (#6489).

The blue curve is data taken when the PRMI was locked for comparison.

You can see that both the upper and lower 55 MHz sideband are amplified by the SRC.

(Some notes)

Currently SRM is slightly misaligned such that the MICH optical gain at AS55Q doesn't increase so much with the presence of SRM.

With this condition I was able to acquire the lock more frequently than how it used to be on the Wednesday.

The next step is to gradually align SRM, to optimize the controls and to repeat this process several times until SRM is fully aligned.

Somehow I lost the good alignment, where the lock can be frequently acquired and hence I didn't go further ahead.

I will try locking the DRMI during the weekend again. My goal is to take time series when the DRMI is being locked and sensing matrix.

I was going to try some locking, but things are a little too noisy. 

Just so Kiwamu knows what I did today, in case he comes back....

I ran LSCoffsets, and aligned both X and Y arms and saved their positions, and aligned MICH, and saved the BS position. 

I'll play with it more later, when there aren't trucks driving around outside that I can hear / feel in the control room.

 After giving up on locking, the MC is getting unlocked every now and again (2 times so far in the last few minutes) from transient seismic stuff.

Here is a time series when the DRMI is being locked.

You can see that the AS110 goes up because the SRCL is engaged and amplifies the 55 MHz sidebands.

   I have worked out the fibers we need to get for the following distribution scheme:

1) We have a laser placed at the 1Y1 rack.  A part of the power is split off for monitoring the laser output and sent to a broadband PD also placed in the same rack.  The RF excitation applied to the laser is split and sent to LSC rack (1Y2) and used to calibrate the full PD+Demod board system for each RFPD.

2) A single fiber goes from the laser to a 11+ way switch located in the OMC electronics cabinet next to the AP table.  From here the fibers branch out to three different tables.

Cable for the laser source to the OMC table:

We also require a cable going from PSL table to the ETMY table:   This is not a part of the RFPD characterisation.  It is a part of the PSL to Y-end Aux laser lock  which is a part of the green locking scheme.  But it is  fiber we need and might as well order it now along with the rest.

If you would like to add anything to this layout / scheme, please comment.  On Monday Eric is going to take a look at this and place orders for the fibers.

(I have included the lengths required for routing the fibers and added another 20% to that ) 

[Jenne/Den/Koji]

We saw some white boxes on the LSC screens.
We found c1iscaux2 is not running.

Once the target was power-cycled, these epics channels are back.
Then c1iscaux2 were burtrestored using the snapshot at 5:07 on 4/16, a day before the power glitch.

I made some modifications to the c1lsc model in order to extract both the error and control signals.

I added pick-offs for the error signals right before IFO DOF filter modules.  These are then sent with GOTOs to outputs.

I also modified things on the control side.  The OAF stuff was picking off control signals before feedforward in/outs.  After discussing with Jenne we decided that it would make sense for the OAF to be looking at the control signals after feedforward.  It also makes sense to define the control signal after the feedforward.  These control signals are then sent with GOTOs to another set of outputs.

Finally, I moved the triggers to after the control signal pickoffs, and right before the output matrix.  The final chain looks like (see attachment):

input matrix --> power norm --> ERR pickoff --> DOF filters --> FF out --> FF in --> CTRL pickoff --> trigger --> output matrix

The error pickoff outputs in the top level of the model are left terminated for the moment.  Eventually I will be hooking these into the new c1cal calibration model.

The model was recompiled, installed, and restarted.  Everything came up fine.