I used scripts/SUS/freeswing-all.csh to give the optics a kick and then turn off their watchdogs and collect the free swinging data.  Final script end time = 993173551. Start taking data ~ 993173751

I had to fix up the script a little: it had amateur stuff in there, such as undefined variables.

It still doesn't work that well. On the new Ubuntu workstations, pianosa, it fails by just not setting some of the EPICS variables using the EZCA stuff.

On Allegra, it failed on ~1 out of 10 commands by returning "epicsThreadOnce0sd epicsMutexLock failed" ???

On Pianosa, it sometimes says, instead, "epicsThreadOnceOsd: pthread_mutex_lock returned Invalid argument.".   Ah...now I understand?

So finally, I had to run the script on op340m to get it to actually run all of its commands. That's right; I used a 15 year old Solaris 9 Blade 150 because none of our fancy new Linux machines could do the job reliably.

Fixing our EZCA situation is a pretty high priority; if the locking scripts fail to run ~1 command every hour its going to completely derail the lock acquisition attempts.

If you want to use the IFO tonight, just run the script again on op340m again when you're done.

 Since the MC1 LRSEN channel is not wasn't working, my input matrix diagonalization hasn't worked today wasn't working. So I decided to fix it somehow.

I went to the rack and traced the signal: first at the LEMO monitor on the whitening card, secondly at the 4-pin LEMO cable which goes into the AA chassis.

The signal existed at the input to the AA chassis but not in the screen. So I pressed the jumper wire (used to be AA filter) down for the channel corresponding to the MC1 LRSEN channel.

It now has come back and looks like the other sensors. As you can see from this plot and Joe's entry from a couple weeks ago, this channel has been dead since May 17th.

The ELOG reveals that Kiwamu caught Steve doing some (un-elogged) fooling around there. Burnt Toast -> Steve.

993190663   =      free swinging ringdown restarted again

The slow readback of the ETMX side seems to also have something flaky and bi-stable. This is not an issue for damping, but it disables the SIDE watchdog for ETMX and makes it unsafe if we accidentally use the wrong damping sign.

 Summary for the week ending June 26th.  (Number of elog entries = 53)

He has moved the levitation stuff for his surf student to Jan's lab in W-Bridge.

Chris Wipf tells me that the EPICS Mutex Jumbo Mumbo can be overcome by upgrading our EPICS. We should get one of Jamie's assistants to get this going on one of the Ubuntu workstations.

I have measured / calculated the latest MICH noise budget.  It doesn't really look all that stellar.

As you can see, we are nowhere near being shot noise limited, since there's a huge discrepancy between all of the measured spectra and the teal Shot Noise line. 

One possible suspect is that the analog whitening filters weren't on when I took my measurements.  I didn't actually check to ensure that they were on, so they might not have been.  Right now we're limited by electronics and other boring noises, so I need to make sure we're limited by the noise of the diode itself (we don't have enough light in the IFO to actually be shot noise limited since that takes 2.5mA for AS55 and I only have 1.1mA, but we should be ~within a factor of 2ish).

I measured the power incident on REFL11 and REFL55.  Steve was concerned that it is too high.  If we consider this elog the incident power levels were REFL11: 30 mW and REFL55: 87 mW. (assuming efficiency of ~ 0.8 A/W @1064nm for the C30642 PD).  However, currently there is a combination of Polarising BS and Half-waveplate with which we have attenuated the power incident on the REFL PDs.  We now have (with the PRM misaligned):

REFL11:  Power incident = 7.60 mW ;  DC out = 0.330 V  => efficiency = 0.87 A/W

REFL55:  Power incident = 23 mW ;  DC out = 0.850 V  => efficiency = 0.74 A/W

and with the PRM aligned::

REFL11:  DC out = 0.35 V  => 8 mW is incident

REFL55: DC out = 0.975 V  => 26 mW is incident

These power levels may go up further when everything is working well.

The max rated photo-current is 100mA => max power 125mW @0.8 A/W.

The WFS2  Transimpedance has been measured to determine if it also suffers from the same 200MHz oscillations seen in WFS1 sensor head

The attached plots (pdf attached) show that the 29.5 MHz peak needs tweaking in Q2 and Q1 seems to have a much lower transimpedance than other quadrants.  The table below summarises the resonances and notches of the ckt

The peak at 10MHz is much sharper than the similar peak at 13MHz in the case of WFS1.  Is this a matter for some concern? 

The 200MHz oscillation once again exists in Q2, Q3 and Q4.  This sensor head will also require the same treatment as WFS1.

What is the power level on MC_REFL_ PDs and WFS  when the MC is not locked?

The manual instructions on the 40m wiki for restarting wouldn't work.  I killed the process okay, but then I got an error saying it "couldn't bind to port 8080, please try again using -p to select port".  The automated script worked though.

The measured change in the REFL DC power with and without PRM aligned seems unacceptably small.  Something wrong ?

The difference in the power with and without PRM aligned should be more than a factor of 300.

         [difference in power] = [single bounce from PRM] / [two times of transmission through PRM ]

                                          = (1-T) / T^2 ~ 310,

where T is the transmissivity of PRM and T = 5.5% is assumed in the calculation.

Also the reflectivity of MICH is assumed to be 1 for simplicity.

Here is the result of the measurement of the sensing matrix in the PRMI configuration.

If we believe the resultant matrix, it is somewhat different from what we expected from a finesse simulation (summary of simulated sensing matrix).

(Motivation)

As a part of the DRMI test plan, we wanted to check the sensing matrices and consequently diagonalize the LSC input matrix.

The matrix of the DRMI configuration has been measured (#4857), but it was a bit too complicated as a start point.

So first in order to make sure we are doing a right measurement, we moved onto a simpler configuration, that is PRMI.

(measurement)

The technique I used was the same as before (#4857) except for the fact that SRM wasn't included this time.

   - PRC was locked to the carrier resonant point. The UGF of MICH and PRC were ~ 110 Hz and 200 Hz respectively.

   - Longitudinally shook BS, ITMs and PRM at 283.103 Hz with an amplitude of 1000 counts using the LOCKIN oscillator in C1LSC.

   - Took the I and Q phase signals from the LOCKIN outputs.

The table below is the raw data obtained from this measurement :

(Conversion of matrix)

 With the matrix shown above, we should be able to obtain the sensing matrix which gives the relation between displacements in each DOF to each signal port.

The measured matrix connects two vectors, that is,

       (signal port vector) = [Measured raw matrix] (SUS actuation vector),   -- eq.(1)

where

       (signal port vector) = (AS55_I, AS55_Q, REFL11_I, REFL11_Q)T   in unit of [counts],

    (SUS actuation vector) = (BS, ITMX, ITMY, PRM)T   in units of [counts].

Now we break the SUS actuation vector into two components,

       (SUS actuation vector [counts])  = (actuator response matrix [m/counts])-1 * (MICH, PRM [m] )^T   -- eq.(2)

 where

       (actuator response matrix) =  2.05x10-13 * ( [1   ,  0.217, -0.216,   0  ],

                                                 [ 0.5,  0.109 -0.108, 0.862]  )  in unit of [m/counts]

These values are coming from the actuator calibration measurement.

In the bracket all the values are normalized such that BS has a response of 1 for MICH actuation.

Combining eq.(1) and (2) gives,

     (signal port vector) = (measured raw matrix) * (actuator response matrix)-1 * (MICH, PRM)T

And now we define the sensing matrix by

     (sensing matrix) = (measured raw matrix) * (actuator response matrix)-1

The sensing matrix must be 4x2 matrix.

For convenience I then converted the I and Q signals of each port into the absolute value and phase.

       ABS = sqrt((AAA_I)2 +(AAA_Q)2 ),

       PHASE = atan (AAA_Q / AAA_I),

where AAA is either AS55 or REFL11.

(Resultant matrix)

The table below is the resultant sensing matrix.

ABS represents the strength of the signals in unit of [cnts/m], and PHASE represents the demodulation phases in [deg].

There are several things which I noticed :

   - The demodulation phase of MICH=>AS55 and PRC=>REFL11 are close to 0 or 180 deg as we expected.

      This is a good sign that the measurement is not something crazy.

   - AS55 contains a big contribution from PRC with a separation angle of 152 deg in the demodulation phase.

     In AS55 the signal levels of MICH and PRC were the same order of magnitude but PRC is bigger by a factor of ~4.

     However the finesse simulation (see wiki page) shows a different separation angle of 57 deg and MICH is bigger by factor of ~6.

  - REFL11 is dominated by PRC. The PRC signal is bigger than MICH by a factor of ~100, which agrees with the finesse simulation.

    However the separation angle between PRC and MICH are different. The measurement said only 19 deg, but the simulation said ~ 90 deg.

  - Woops, I forgot to calibrate the outputs from the LOCKIN module.

    The whole values must be off by a certain factor due to the lack of the calibration , but fortunately it doesn't change the demodulation phases.

Our design kits are full again. They are waiting for a new brilliant PD design.

1. Suresh and I completed the alignment of the fibre and the three mirrors on the ETMY table.

2. We managed to get an output beam power of around 60% using the Ophir(Orion/PD) power meter to finetune the alignment. The power of the input beam is 74.4 mW and of the output beam is 38.5 mW.

3. The coupler on the output side of the fibre which had been put there to help in the alignment has been removed.

4. The picture of the ETMY layout as of now has been attached.

5. The labels A stands for the mirror used to turn the beam direction and B and C stand for the three mirrors used in the alignment of the beam into the coupler,D.(attachment 3).

6. The fibre we used is 50m in length which was barely sufficient to reach the PSL table.

7. So, the fibre has been routed to the PSL table using the fibre tray running below the Y-arm tube as this was the shortest route possible(even though it is a rather acccident prone zone).

8. The fibre has been tied down at regular intervals so that it does not get snagged and pulled up inadvertently.

9. We will start with the preparation of the layout of the PSL table to superpose the two beams on Monday.

I have updated the sus_single_control model, adjusting/cleaning up/simplifying the LSC/POS input signals, and routing new signals to the lockins. Notably one of POS inputs to the part ("lockin_in") was eliminated (see below).

The 6 inputs to the TO_COIL output matrix are now:

LSCPOS + OFFSET + ALT_POS_IN
ASCPIT + OFFSET + SUSPIT + OLPIT
ASCYAW +OFFSET + SUSYAW + OLYAW
SIDE
LOCKIN1
LOCKIN2

The ALT_POS input is used only by the ETMs for the green locking. Just outside of the sus_single_control library part in the ETM models are the green locking controls, consisting of the ETM?_ALS filter bank and the ETM?_GLOCKIN lockin, the outputs from which are summed and fed into the aforementioned ALT_POS input.

As for the SUS lockins (LOCKIN1 and LOCKIN2 in the library model), their input matrix now gets the direct inputs from the OSEMS (before filtering) and the outputs to the coils, after all filtering. These will aid in doing binary output switching tests.

All suspension models (c1sus, c1scx, c1scy) have been rebuild and restarted so that they reflect these changes.

IMPORTANT ELECTRONICS SAFETY LESSON TO FOLLOW

Yesterday, I fried the +15 V power supply rail on one of the Eurocrate extender cards while I was checking out the binary switching in the 1X5 rack.  I will describe what I did it in the hopes that everyone else will be less stupid than me.

I wanted to monitor the voltage across a resistor on the suspension OSEM whitening board.  Since I knew that both sides of the resistor would be at non-zero voltage (including possibly at the power-supply rail), I used a battery-operated scope with floating inputs, so that the scope would not try to pull the probe shield to ground.  That should be OK, although not recommended, as you'll see, because you must be very careful to make sure that the scopes inputs are indeed floating.

Let's call the original signal 'A'.  The trouble came when I then connected another signal (B), whose shield was connected to the ground on the whitening board, to the scope.  Apparently the grounds on the scope inputs are connected, or were in the configuration I was using.  When I connected the signal B, B's ground shorted A's shield to ground, which had been sitting at the +15V rail.  That short circuit then fried the +15V supply line on the extender card I was using (escaping magic smoke was detected).  Thankfully this only blew the extender card, and not the Eurocrate or the Eurocrate power supply or the whitening board or the scope etc, all of which would have been much worse.

The moral of the story is to be very careful when connecting power supply voltages to the shield or ground of a scope.  In short, don't do it.  I didn't ultimately need to, since I could have found other ways to measure the same signal.

I have been checking the binary output switching for the SUS whitening filters. It appears that the whitening switching is working for (almost) all the vertex suspensions (BS, ITMX, ITMY, PRM, SRM), but not for the ETMs.

The table below lists the output from my switch-checking script (attached). The script uses the SUS digital lockin to drive one coil and measure the same coil's OSEM response, repeating for each coil/OSEM pair. I used a lockin drive frequency of about 10 Hz, at which the whitening filter should have 10 db of gain.

All but one of the vertex OSEMS show the proper response (~10db gain at 10Hz) when the whitening is switched on from the digital controls. ITMY UL appears to not be switching, which I fear is due to my electronics fail noted in my previous log post.  The ETMs are clearly not switching at all.

I will try to get the ETM switching working tomorrow, as well as try to asses what can be done about the ITMY UL switch.  After that I will work on confirming the coil drive dewhite switching.

lockin settings

freq: 10.123 Hz
amp: 10000
I/Q filters: 0.1 Hz LP, 4-pole butterworth

response

BS
ul : 3.31084503062 = 10.3987770676 db
ll : 3.34162124753 = 10.4791444741 db
sd : 3.43226254574 = 10.7116100229 db
lr : 3.28602651913 = 10.3334212798 db
ur : 3.29361593249 = 10.3534590969 db

ITMX
ul : 3.37499773336 = 10.5654697099 db
ll : 3.2760924572  = 10.3071229966 db
sd : 3.13374799272 =  9.9212813757 db
lr : 3.28133776018 = 10.3210187243 db
ur : 3.37250879937 = 10.5590618297 db

ITMY
ul : 0.99486434364 = -0.0447226830807 db
ll : 3.39420873724 = 10.6147709414 db
sd : 3.88698713176 = 11.7922620572 db
lr : 3.357123865   = 10.5193473069 db
ur : 3.37876008179 = 10.5751470918 db

PRM
ul : 3.26758918055 = 10.2845489876 db
ll : 3.32023820566 = 10.4233848529 db
sd : 3.25205538857 = 10.2431586766 db
lr : 3.24610681962 = 10.227256141  db
ur : 3.31311970305 = 10.4047425446 db

SRM
ul : 3.30506423619 = 10.3835980943 db
ll : 3.28152094133 = 10.3215036019 db
sd : 3.08566647696 =  9.7869796462 db
lr : 3.30298270419 = 10.378125991  db
ur : 3.3012249406  = 10.3735023505 db

ETMX
ul : 0.99903400106 = -0.00839461539757 db
ll : 0.99849991349 = -0.0130393683795 db
sd : 1.00314092883 =  0.0272390056874 db
lr : 1.00046493718 =  0.00403745453682 db
ur : 1.00265600785 =  0.0230392084558 db

ETMY
ul : 1.00223179107 =  0.0193634913327 db
ll : 0.96755532811 = -0.286483823189 db
sd : 1.00861855271 =  0.0745390477589 db
lr : 1.05718545676 =  0.483023602007 db
ur : 0.99777406174 = -0.0193558045143 db

New LSC screen is 80% completed.

It is now accessible from the LSC menu of "sitemap".

Most of the part in the screen is clickable such that it launches another screen depending on the location of the click.

The bottom part of the screen still need some work.

RFPD screen is temporary

LSC control screen is also temporary

DAC overflow indicators are still broken.

Channel assignment of the whitening filters are arbitrary so far.

Here I show several issues that we have encountered in the quad magnetic levitation system. It would be great if you can give
some suggestions and comments (Poor haixing is crying for help)

The current setup is shown by the figure below (I took the photo this morning):

Basically, we have one heavy load which is rigidly connected to a plane that we try to levitate. On corners of the
plane, there are four push-fit permanent magnets. Those magnets are attracted by four other magnets which are
mounted on the four control coils (the DC force is to counteract the DC gravity). By sensing the position of the plane
with four OSEMs (there are four flags attached on the plane), we try to apply feedback control and levitate the plane.
We have made an analog circuit to realize the feedback, but it is not successful. There are the following main issues
that need to be solved:

(1) DC magnetic force is imbalanced, and we found that one pair has a stronger DC force than others. This should
be able to solved simply by replacing them with magnets have comparable strength to others.

(2) The OSEM not only senses the vertical motion, but also the translational motion. One possible fast solution is to
cover the photodiode and only leave a very thin vertical slit so that a small translational motion is not sensed.
Maybe this is too crappy. If you have better ideas, please let me know. Koji suggested to use reflective sensing
instead of OSEM, which can also solve the issue that flags sometimes touche the hole edge of the OSEM and
screw up the sensing.

(3) Cross coupling among different degrees of freedom. Basically, even if the OSEM only senses the vertical motion,
the motion of four flags, which are rigidly connected to the plane, are not independent. In the ideal case, we only
need to control pith, yaw and vertical motion, which only has three degrees of freedom, while we have four sensing outputs
from four OSEMs. This means that we need to work out the right control matrix. Right now, we are in some kind of dilemma.
In order to obtain the control matrix, we first have to get the sensing matrix or calibrate the cross coupling; however, this is
impossible if the system is unstable. This is very different from the case of quad suspension control used in LIGO,
in which the test mass is stable suspended and it is relatively easy to measure the cross coupling by driving the test mass
with coils. Rana suggested to include a mechanical spring between the fixed plane and levitated plane, so that
we can have a stable system to start with. I tried this method today, but I did not figure out a nice way to place the spring,
as we got a hole right in the middle of the fixed plane to let the coil connectors go though. As a first trial, I plan to
replace the stop rubber band (to prevent the plane from getting stuck onto the magnets) shown in the figure with mechanical
springs. In this case, the levitated plane is held by four springs instead of one. This is not as good as one, because
of imbalance among the four, but we can use this setup, at least, to calibrate the cross coupling. Let me know if you come
up better solution.

After those issues are solved, we can then implement Jamie's Cymac digital control, which is now under construction,
to achieve levitation.

 I don't know if this would work, but it might be worth a try:

You've achieved single levitation before, with fairly good stability.  Can you try taking each magnet + coil and finding the DC coil current required to hold a mass at a given position?  If you can hold the same mass at the same place with all the different magnets+coils, then you're exerting the same force against gravity, so your DC forces are balanced. 

Update of Week 3 Work:

-I've finished reading The Art of Electronics Ch 1, 2, and 4.

-The mechanical stage for the horizontal displacement measurements is set up.

-I've opened up the circuit box for the quad photodiode and am currently working on the circuit diagram for the box and for the quad photodiode sensors.

Later this week, I plan to finish the circuit diagrams and figure out how the circuits work with the four inputs. I also plan to start working on my first

progress report.

Photo diodes stored in the east arm cabinet E4:  ALL PDs  meet here, fast  or slow......

Of course I made a mistake in my calculation of the sensing matrix. I will figure out which point I mistook.

The MICH signal must have the demodulation phase of around 90 deg in AS55

because we had adjusted the demodulation phase such that the MICH signal mostly appears on AS55_Q.

LSC model has been updated and running,

- Now the power and signal recycling cavity lengths are named "PRCL" and "SRCL" in stead of three letter names without "L".

- Names for the trigger monitor were fixed. They are now "C1:LSC-DARM_TRIG_MON", etc., instead of "...NORM"

- Channel order of the DC signals for PDDC_MTRX and TRIG_MTRX were changed.

It was "TRX, TRY, REFL, AS, POP, POX, POY" but now "AS, REFL, POP, POX, POY, TRX, TRY".

We should change the locking script to accomodate these changes.

I have finished drawing the circuit diagrams for the quad photodiode boxes. Here are copies of the circuit diagram.

There are three main operation circuits in the quad photdiode box: a summing circuit (summing the contributions from the four inputs),

a Y output circuit (taking the difference between the input sums 3+2 and 1+4), and an X output circuit (taking the difference between the

input sums 3+4 and 1+2). I will complete an mini report on my examination and conclusions of the QPD circuit for the suspension wiki tomorrow.

Today I wanted to investigate the MC Length path situation for obscure reasons.

Jamie has started to revert the "ALTPOS" effect on the MC mirrors. So far, the screens and SLOW channels have been fixed, but the fast channels still say "ALTPOS" in the dataviewer instead of "MCL".

I also noticed that all of our old ADCU channels for diagnosing the PSL, MC, ISS, PMC ,etc. are completely AWOL. Let's blame Joe.

I think that there are probably some ADC channels available and that we'll just have to figure out what Joe intended for this. We certainly need it if we want to diagnose our PMC, ISS, FSS, MC, etc. Kiwamu tells us that the old PSL/IOO AA chassis is being used for some of the GCV signals, so its likely that we just have to do the appropriate channel name mapping in the DAQCONFIG tool.

Forging ahead with no data, I made up some filters in the MC2-MCL filter bank so that there could be a stable crossover between the laser path. I was able to turn it on and get some suppression of the FSS-FAST control signal, but there's no way to be sure without the fast channels. We gotta get Jamie to help us out once he finished the ETM BO mess.

[Jenne, Koji]

We have tested the LSC whitening filters. In summary, they show the transfer functions mostly as expected (15Hz zerox2, 150Hz pole x2).
Only CH26 (related to the slow channel "C1:LSC-PD9_I2_WhiteGain. VAL NMS", which has PD10I label in MEDM) showed different
phase response. Could it be an anti aliasing filter bypassed???

The 32 transfer functions obtained will be fit and summarized by the ZPK parameters.

Method:

The CDS system was used in order to get the transfer functions
- For this purpose, three filter modules ("LSC-XXX_I", "LSC-XXX_Q", "LSC-XXX_DC") were added to c1lsc
in order to allow us to access to the unused ADC channels. Those filter modules have terminated outputs.
The model was built and installed. FB was restarted in order to accomodate the new channels.

- Borrow a channel from ETMY UL coil output mon. Drag the cable from the ETMY rack to the LSC analog rack.
- Use 7 BNC Ts to split the signal in to 8 SMA cables.
- Put those 8 signals into each whitening filter module.

- The excitation signal was injected to C1:SUS-ETMY_ULCOIL_EXC by AWGGUI.
- The transfer functions were measured by DTT.
- The excitation signal was filtered by the filter zpk([150;150],[15;15],1,"n")
   so that the whitened output get flat so as to ensure the S/N of the measurement.

- For the switching, we have connected the CONTEC Binary Output Test board to the BIO adapter module
   in stead of the flat cable from the BIO card. This allow us to switch the individual channels manually.

- The whitening filters of 7 channels were turned on, while the last one is left turned off.
- We believe that the transfer functions are flat and equivalent if the filters are turned off.
- Use the "off" channel as the reference and measure the transfer functions of the other channels.
- This removes the effect of the anti imaging filter at ETMY.

- Once the measurement of the 7 channels are done, switch the role of the channels and take the transfer function for the remaining one channel.

Result:

- We found the following channel assignment

• The ADC channels and the PDs. This was known and just a confirmation. 
• The ADC channels and the WF filter on MEDM (and name of the slow channel)

- We found that the binary IO cable at the back of the whitening filter module for ADC CH00-CH07 were not connected properly.
This was because the pins of the backplane connector were bent. We fixed the pins and the connector has been properly inserted.

- CH26 (related to the slow channel "C1:LSC-PD9_I2_WhiteGain. VAL NMS", which has PD10I label in MEDM) showed different
phase response from the others although the amplitude response is identical.

Summary of the channel assignment (THEY ARE OBSOLETE - SEPT 20, 2011)

ADC                    Whitening Filter
CH  PD                 name in medm   related slow channel name for gain
---------------------------------------------------------------------------
00  POY11I             PD1I           C1:LSC-ASPD1_I_WhiteGain. VAL NMS
01  POY11Q             PD1Q           C1:LSC-ASPD1_Q_WhiteGain. VAL NMS
02  POX11I             PD2I           C1:LSC-SPD1_I_WhiteGain. VAL NMS
03  POX11Q             PD2Q           C1:LSC-SPD1_Q_WhiteGain. VAL NMS
04  REFL11I            PD3I           C1:LSC-POB1_I_WhiteGain. VAL NMS
05  REFL11Q            PD3Q           C1:LSC-POB1_Q_WhiteGain. VAL NMS
06  AS11I              PD4I           C1:LSC-ASPD2_I_WhiteGain. VAL NMS
07  AS11Q              PD4Q           C1:LSC-ASPD2_Q_WhiteGain. VAL NMS
08  AS55I              AS55_I         C1:LSC-ASPD1DC_WhiteGain. VAL NMS
09  AS55Q              AS55_Q         C1:LSC-SPD1DC_WhiteGain. VAL NMS
10  REFL55I            PD3_DC         C1:LSC-POB1DC_WhiteGain. VAL NMS
11  REFL55Q            PD4_DC         C1:LSC-PD4DC_WhiteGain. VAL NMS
12  POP55I             PD5_DC         C1:LSC-PD5DC_WhiteGain. VAL NMS
13  POP55Q             PD7_DC         C1:LSC-PD7DC_WhiteGain. VAL NMS
14  REFL165I           PD9_DC         C1:LSC-PD9DC_WhiteGain. VAL NMS
15  REFL165Q           PD11_DC        C1:LSC-PD11DC_WhiteGain. VAL NMS
16  NC (named XXX_I)   PD5I           C1:LSC-SPD2_I_WhiteGain. VAL NMS
17  NC (named XXX_Q)   PD5Q           C1:LSC-SPD2_Q_WhiteGain. VAL NMS
18  AS165I             PD6I           C1:LSC-SPD3_I_WhiteGain. VAL NMS
19  AS165Q             PD6Q           C1:LSC-SPD3_Q_WhiteGain. VAL NMS
20  REFL33I            PD7I           C1:LSC-POB2_I_WhiteGain. VAL NMS
21  REFL33Q            PD7Q           C1:LSC-POB2_Q_WhiteGain. VAL NMS
22  POP22I             PD8I           C1:LSC-ASPD3_I_WhiteGain. VAL NMS
23  POP22Q             PD8Q           C1:LSC-ASPD3_Q_WhiteGain. VAL NMS
24  POP110I            PD9I           C1:LSC-PD9_I1_WhiteGain. VAL NMS
25  POP110Q            PD9Q           C1:LSC-PD9_Q1_WhiteGain. VAL NMS
26  NC (named XXX_DC)  PD10I          C1:LSC-PD9_I2_WhiteGain. VAL NMS
27  POPDC              PD10Q          C1:LSC-PD9_Q2_WhiteGain. VAL NMS
28  POYDC              PD11I          C1:LSC-PD11_I_WhiteGain. VAL NMS
29  POXDC              PD11Q          C1:LSC-PD11_Q_WhiteGain. VAL NMS
30  REFLDC             PD12I          C1:LSC-PD12_I_WhiteGain. VAL NMS
31  ASDC               ASDC           C1:LSC-PD12_Q_WhiteGain. VAL NMS
---------------------------------------------------------------------------

While closing up the whitening shop for the night, I noticed that the ITMX whitening state (Whitening "On") is opposite that of all other suspensions (they all have Whitening "Off").  I don't know which way is correct, but I assume they should all be the same.  Once all the whitening and BO testing is done, we should make sure that they're all the way we want them to be.

Also, Koji and I are leaving ETMX free swinging.  That's the way we found it, presumably from Jamie's BO testing at the end station today.  We don't know what the optic's story is, so we're leaving it the way we found it.  Jamie (or whomever left it free swinging), can you please restore it when it is okay to do so?  Thanks!

Status update of the absolute length (ABSL) measurement:

 - To accommodate the ABSL stuff, the AS path was relocated on the AP table.

     (In this evening Jenne was able to lock MICH with AS55, so it's working fine.)

 - On the AP table all of the necessary items, including the NPRO, a Faraday, some mirrors and etc., were in place

 - The mode matching was coarsely done. The Rayleigh range looked reasonably long.

 - Fine alignments will be done tomorrow

 - Also a picture of the setup will be uploaded in the morning.

Dave Barker pointed out last week that the webview of our simulink model files, generated from the installed models (i.e. in /opt/rtcds/caltech/c1/target/<system name>/simLink/) was not handling libraries properly.  Essentially the web pages generated couldn't see inside library parts.

This was caused by 2 problems.  The first being the userapps not being in the matlab path when the slwebview call was done, so it couldn't even find the libraries.  The second problem is the slwebview code by default doesn't follow libraries and links, and needs a special command to be told to do so.

I added the following lines to the webview_simlink_update.m file:

addpath('/opt/rtcds/caltech/c1/core/trunk/src/epics/simLink/lib')
for sub = {'cds','isc','isi','sus','psl'}
 for spath = {'common/models','c1/models/lib'}
   addpath(['/opt/rtcds/caltech/c1/userapps/release/' sub{1} '/' spath{1}]);
 end
end

I also changed the following:

temp = slwebview(final_files{x},'viewFile',false);

became

temp = slwebview(final_files{x},'viewFile',false,'FollowLinks','on','FollowModelReference','on');

After confirming these changes worked, I have sent a corrected version to Dave and Keith.

The webview results can be found at: https://nodus.ligo.caltech.edu:30889/FE/

I measured the power in various beams on the AP table to check and see if any beam is having too much power. 

I am uploading two pics one is in the "high power state" and the other is the "low power state".   High power in the MC REFL PD occurs when the MC is unlocked.  In addition the WFS also will see this  hike in power. We wish to make sure that in either state the power levels do not exceed the max power that the PDs can tolerate.

Low Power state: MC locked, PRM not aligned.                                                   High Power state: MC unlocked,  PRM aligned.

As noted before the  resonances had to be tuned to the 29.5 MHz ( or rather 29.485 MHz to match with the Wenzel) and notches to twice that frequency (58.97 MHz). 

I tuned these frequencies and remeasured the transimpedance curves .  These are in the attached pdf file. 

Some notes.

1) The variable inductances on the PCB have a ferrite core which is actually ferrite powder compacted around an iron screw.  The screw serves to provide the adjustability.  However, being iron, it seems to have rusted and so the cores are stuck.  So several of the cores splintered when I tried to adjust the frequencies.

2) The WFS1 had a finger print/smudge on the face of the PD.  I drag wiped it with methanol to get rid of it.

WFS1 is ready to go on the table.  I am going to work on WFS2 today.

This was certainly my fault, probably left over from early debugging of my BO switch check script.  I've turned the ITMX whitening all off, to match the other suspensions.

Again, this was my fault.  Sorry.  I just accidentally left this off when I finished yesterday.  Much apologies.  I've turned the ETMX watchdog back on.

 The framebuilder just needed to be restarted to pull in the fixed channel names.  I restarted the framebuilder and now the channels (C1:SUS-MC2_MCL_*) are showing up properly.

Here is a picture of the latest ABSL setup at the east part of the AP table.

(Some notes )

 - The ABSL laser is injected from the AP port.

  - A 90 % reflection BS was installed just after the NPRO, this is for sampling a 10% of the laser to the PSL table.

    However, I've just realized that this is not a nice way because the 10 % beam doesn't  go through the Faraday. Whoops.

 - A polarzser cell at the input side of the Faraday doesn't let any beam go through it for some reasons (broken ?).

    Therefore instead of having such a bad cell, a cube PBS was installed.

 -  A room was left on the table for the AS165 RFPD (green-dashed rectangular in the picture).

Lightwave M126-1064-700 lasers  sn415  at east end of the Y arm and  sn201 at the AP table  are connected individually  to one each EMERGENCY LASER SHUT OFF SWITCH. 

(Just a quick report)

The fine alignment of the ABSL laser injection was successfully done.

I was able to see the DRMI fringings at the AS camera. The ABSL beam is injected from the AS port, therefore what I saw on the camera was the reflection back from the interferometer.

(Things to be done)

 -  A beat-note setup on the PSL table.

 - Refinement of the mode matching. The beam spot on the AS camera is a bit bigger, so I should more tightly focus the injected beam.

As I recently had trouble getting all of the SUS SENSOR channels at once from NDS2, I asked J.Z. for help. He found that the number of buffers on mafalda was set to only allow a small amount of data to be requested at one time.

He's going to have to figure out a more permanent fix, but for now he's increased the data buffer size to allow somewhat larger chunks to be gotten. I have made a work around in matlab, which gets smaller chunks and then cats them together.

Its in SUS/peakFit/.

This was the WFS whose photodiode was repaced as the old one was found to be damaged. 

I retuned the resonances and the notches of all the quadrant and have attached a pdf file of my measurements.

Some notes:

a)  The variable inductor on WFS2Q2 quadrant may need to be changed. The ferrite code has come of the solinoid and is just held in place due to friction..  It may be easily disturbed.    So though i chose to leave it in place for now,  it will need to be replace in case the Q3 misbahaves..

b) In general the frequencies have shifted a bit when I closed the lid of tne WFS sensor head.

WFS1 and 2 have been installed on the AP table and are functional. I am shifting attention to the software.

What is implicit in Suresh's entry is that we decided to run the WFS with the 10 dB internal attenuation set to ON as the nominal. In the past, we have always had all the attenuation OFF for max gain. The layout of the WFS is such that we get that nasty 200 MHz oscillation due to crosstalk between the 2 MAX4106 opamps for each quadrant. The 10 dB attenuator is able to reduce the positive feedback enough to damp the oscillation.

In principle, this is still OK noise-wise. I think the thermal noise of the resonant circuit should be ~2-3 nV/rHz. Then the first opamp has a gain of 5, then the -10 dB attenuator, then another gain of 5. The noise going to the demod board is then ~10-15 nV.

The real noise issue will be the input noise of the demod board. As you may recall, the output of the AD831 mixer goes to a AD797. The AD797 is a poor choice for this application. It has low noise only at high frequencies. At 10 Hz, it has an input voltage noise of 10 nV/rHz and a current noise of 20 pA/rHz. If we wanted to use the AD797 here, at least the RC filter's resistor should be reduced to ~500 Ohms. Much better is to use an OP27 and then choose the R so as to optimize the noise.

We should also be careful to keep the filter frequency low enough so as not to rate limit the OP27. From the schematic, you can see that this circuit is also missing the 50 Ohm termination on the output. There ought to be the usual high-order LC low pass at the mixer output. The simple RC is just not good enough for this application.

As a quick fix, I recommend that when we next want to up the WFS SNR, we just replace the RC with an RLC (R = 500 Ohms, L = 22 uH, C = 1 uF).

I have fixed the binary whitening switching for the ETMs (ETMX and ETMY).  See below for a description of what some of the issues were.

The ETMX whitening/no-whitening response (same measurements performed in my previous post on checking vertex sus whitening switching) looks as it should.  The ETMY response seems to indicate that the switching is happening, but the measurements are very noise.  I had to up the averaging significantly to get anything sensible.  There's something else going on with ETMY.  I'll follow up on that in another post.

response

ETMX
ul : 3.28258088774 = 10.3243087313 db
ll : 3.31203559803 = 10.4018999194 db
sd : 3.27932572306 = 10.3156911129 db
lr : 3.28189942386 = 10.3225053532 db
ur : 3.31351020008 = 10.4057662366 db

ETMY
ul : 2.9802607099  =  9.4850851468 db
ll : 1.46693103911 =  3.3281939600 db
sd : 2.19178266285 =  6.8159497462 db
lr : 2.2716636118  =  7.1268804285 db
ur : 3.42348315519 = 10.6893639064 db

End rack cable diagrams inconsistent with binary channel mapping

One of the big problems was that the most up-to-date end rack cable diagrams (that I can find) are inconsistent with the actual binary mapping. The diagram says that:

• BO adapter chassis output A (ch 1-16)   --> CAB_1X4_26 --> cross-connect 1X4-B7 (carrying QPD whitening switching signals)
• BO adapter chassis output B (ch 17-32) --> CAB_1X4_27 --> cross-connect 1X4-A6 (carrying OSEM whitening switching signals)

In fact, the binary outputs are switched, such that output A carries the OSEM signals, and output B carries the QPD whitening signals.

I SWITCHED THE CABLES AT THE BINARY OUTPUT ADAPTER CHASSIS so that:

• BO adapter chassis output A (ch 1-16)   --> CAB_1X4_27 --> cross-connect 1X4-A6 (carrying OSEM whitening switching signals)
• BO adapter chassis output B (ch 17-32) --> CAB_1X4_26 --> cross-connect 1X4-B7 (carrying QPD whitening switching signals)

The rest of the wiring remains the same.

I made the same transformation for ETMY as well.

I found many of the core optic (ETMs, ITMs, BS, PRM, SRM) suspension DOF damping controllers (SUSPOS, SUSPIT, SUSYAW, SUSSIDE) to be in various states of disarray:

• Many of the controllers did not have their "Cheby" and "BounceRoll" filters switched on.
• Some of the controllers didn't even have the Cheby or BounceRoll filters at all, or had other different filters in their place.
• ETMY was particularly screwy (I'll make a separate follow-up post about this)
• A bunch of random other unused filters lying around.
• oplev servos not on
• etc.

I went around and tried to clean things up, by "normalizing" all of the DOF damping filter banks, ie. giving them all the same filters and clearing out unused filters, and then turning on all the appropriate filters in all core optic damping filter banks ("3:0.0", "Cheby", "BounceRoll").  I also went sure that all the outputs were properly on, and the oplev servos were on.

A couple of the optics had to have their gains adjusted to compensate for filter changes, but nothing too drastic.

Everything now looks good, and all optics are nicely damped.

I didn't touch the MC sus damping controllers, but they're in a similar state of disarray and could use a once-over as well.

I'm not sure what happened to ETMY SUS, but it was in a pretty bad state.  Bad burt restore, I would guess.

Most egregiously, the inputs to all of the coil output filters were switched off.  This is a bit insidious, since these inputs being off doesn't show up on the overview screen at all.  This explains why ETMY had not been damping for the last couple of day, and why my binary whitening switching measurements were nonsense.

I also found that ETMYs damping filter was a 30 Hz high pass, instead of the 3 Hz high pass in all the other suspension controllers.  Unfortunately a messed up burt restore can't explain that.

I normalized the ETMY controller to match all of the other controllers (ie. gave it a nice new 3 Hz high pass), adjusted gains accordingly, and now ETMY is behaving nicely.

After finally figuring out what was messed up with ETMY I was able to get good measurements of the binary whitening switching on ETMY to determine that it is in fact working now:

ETMY
ul : 3.2937569959  = 10.3538310999 db
ll : 3.28988426634 = 10.3436124066 db
sd : 3.34670033732 = 10.4923365497 db
lr : 3.08727050163 =  9.7914936665 db
ur : 3.27587751842 = 10.3065531117 db

Actually, ETMY was the only good one. They should all have the 30 Hz High pass as the damping filter. I think these details are in the elog entry that we originally made while doing ETMY.

They should all also have a 3:30 in the XXSEN to compensate the whitening. The logic is supposed to be that FM1 is ON when the hardware whitening is ON. This is the opposite of the old logic and its why the damping filter has to be moved from 3 to 30 Hz.

         MC1    MC2    MC3    ETMX   ETMY   ITMX   ITMY   PRM    SRM    BS     mean   std
Pitch   0.671  0.747  0.762  0.909  0.859  0.513  0.601  0.610  0.566  0.747  0.698  0.129
Yaw     0.807  0.819  0.846  0.828  0.894  0.832  0.856  0.832  0.808  0.792  0.831  0.029
Pos     0.968  0.970  0.980  1.038  0.983  0.967  0.988  0.999  0.962  0.958  0.981  0.024
Side    0.995  0.993  0.971  0.951  1.016  0.986  1.004  0.993  0.973  0.995  0.988  0.019

There is a large amount of variation in the frequencies, even though the suspensions are nominally all the same. I leave it to the suspension makers to ponder and explain.

This CSHRC mangling on Feb 4 did more than re-arrange FB binaries.

It broke the path to MEDM for the 32-bit machines in the lab (e.g. mafalda) and stopped the MEDM snapshots from being posted onto our MEDM Status Web Page.

This is because, in addition to the paths mentioned in the above elog, the paths to the EPICS directories were also commented out. I've re-inserted them into our

.cshrc file in the 32-bit section; the statScreen CRON that Yoichi set up is now back in business.

* for some reason, the 'cronjob.sh' script is wiping out its own log file. It would be great if someone who understands stderr output re-direction can fix it so that the log-file from each run is retained until the next time cron runs.

Summary of the week ending July 3rd.  Number of elog entries = 44 

- SUS

- LSC

- MC work

- CDS

- ABSL

- Fiber experiment

- TT characterization

- Configuration and other topics