ELOG 40m

SAFETY

safety glasses required

I just opened the MOPA shutter so PA is warming up.

High power beam path is cleared and laser safety glasses required.

865

Thu Aug 21 10:24:20 2008

laser safe mode condition

SAFETY

The MOPA and PSL shutters are closed.
Manual beam blocks are in place.
Enclosure interlock is enabled.
No other high power laser is in operation.

We are in laser safe of operation for visiting students from Japan

NO safety glasses required

864

Wed Aug 20 18:09:48 2008

Being suspicious of FSS PC path as the culprit of the MC unlocks, I opened the FSS box and connected a probe to the TP7,
which is a test point in the PC path (before high voltage amplifier).
The signal is routed to an unused fast DAQ channel in the IOO rack. It is named C1:IOO-MC_TMP1 and recorded by the frame
builder. You can use this channel as a generic test DAQ channel later.

By looking at the attachment, the PC path (C1:IOO-MC_TMP1) goes crazy at the same time as other channels. So probably
it is not the trigger for the MC unlock.

Then I noticed the WFS signals drift away just before the unlock as shown in the attached plot. So now the WFS is the
main suspect.
Rob tweaked MC1 pitch to center the WFS QPDs while the MC is not locked. It improved the shape of the MC reflection.
However, the sudden MC unlock still happens. We then lowered the WFS gain from 0.5 to 0.3. Did not change the situation.
It looks like the MC length loop starts oscillating after the WFS signals drift away.
We will measure the WFS and MC OPLTF to see the stability of the loops tomorrow.

Attachment 1: MC-unlock.png

863

Wed Aug 20 17:02:01 2008

More FIR to IIR

I tested another method for converting from FIR to IIR other than the 2 mentioned in post 841.
I got this one from Yoichi, called poles fitting, you can read about it more if you want at: http://www.rssd.esa.int/SP/LISAPATHFINDER/docs/Data_Analysis/DA_Six/Heinzel.pdf.

Seems it's not doing much good for us though.

I am attaching a PDF file with the plots, which have N=50,100,600,1000, respectivaly.

Attachment 1: polefit1.pdf

862

Wed Aug 20 13:23:32 2008

I was able to lock the DRMI this afternoon. All the optical levers have been centered.

861

Wed Aug 20 12:39:11 2008

I attempted to model the noise produced by the mirror defects in the ETMX images, in order to better assure that the fit to the beam Gaussian in these images is actually accurate. My first attempt involved treating the defects as random Gaussians which were scaled by the power of the beam's Gaussian. This didn't work at all (it didn't really look like the noise on the ETMX), and resulted in very different behavior from the fitting software (it fit to one of the noise peaks, instead of the beam Gaussian). I'll try some other models another time.

I made a copy of the ezcaservo source code and added options to it that allow the addition of minimum value, maximum value, and slew rate limits. This should allow the camera code to servo on ITMX without accidently driving the mirror too far or too fast. In order to get the code to recompile, I had to strip out part of the servo that changed the step value based on the amount of time that had elapsed (it relied on some GDS libraries and header files). Since the amount of time that passes is reasonably constant (about 2-3 steps per second) and the required accuracy for this particular purpose isn't extremely high, I didn't think it would matter very much.

I put together two MATLAB functions that attempt to convert pixel position in an image to actual position in real space. The first function takes four points that have known locations in real space (with respect to some origin which the camera is pointing at) and compares them to where those 4 points fall in the image. From the distortion of the four points, it calculates the three rotational angles of the the camera, as well as a scaling factor that converts pixels to real spatial dimensions. The second function takes these 4 parameters and 'unrotates' the image, yielding the positions of other features in the image (though they must be on the same flat plane) in real space. The purpose of this is to allow the cameras to provide positions in terms of physically meaningful units. It should also decouple the x and y axes so that the two dimensions can be servo'd on independently. Some results are attached; the 'original' image is the image as it came out of the camera (units in pixels), while the 'modified' image is the result of running the two functions in succession. The four points were the corners of the 'restricted access' sign and of the TV screen, while the origin was taken as the center of the sign or the TV. The accuracy of the transformation is reasonably good, but seems to depend considerably on assuring that the origin chosen in real space matches the origin in the image. To make these the same, they will be calculated by taking the intersections of the 2 lines defined by 2 sets diagonal points in each image. The first function will remain in MATLAB, since it only needs to be run once each time the camera is moved. The second function must be ported to C since the transformation must be done in realtime during the servo.

Joe and I attempted another scan of the PMC this morning. We turned the laser power down by a factor of ~50 (reflection off of the unlocked PMC went from ~118 to ~2.2) and blocked one beam in the MZ. We scanned from 40 V to 185 V ( -1 to -4.25 on the PZT ramp channel) with periods of 60 seconds and 10 seconds. In both cases, thermal effects were still clearly visible. We turned the laser power down by another factor of 2 (~1 on the PMC reflection channel), and did a long scan of 300 seconds and a short scan of 10 seconds. The 10 second scan produced what may be clean peaks, although there was clear digitization noise, while the peaks in the 300 second scan showed thermal effects. I've yet to actually analyze the data closely, however.

Attachment 1: OriginalSignImage.png

Attachment 2: ModifiedSignImage.png

Attachment 3: OriginalTVImage.png

Attachment 4: ModifiedTVImage.png

860

Wed Aug 20 12:04:47 2008

Better diagonalization of PRM input matrix

The values here should replace those in entry #851 from yesterday.

After checking the results of the input matrix diagonalization, I have determined that Sonia's method (described in LIGO-T070168) is more effective at isolating the eigenmodes than Shihori's method (LIGO-T040054).

So, the actual new PRM input matrices are as follows:

	POS	PIT	YAW
UL	0.9678	1.000	0.7321
UR	1.000	0.8025	-0.9993
LR	0.7235	-1.1230	-1.0129
LL	0.6648	-1.0452	1.0000

Attached are plots of the spectra of the eigenmodes, using both Shihori's and Sonia's methods. Note that there isn't a good way to get the side peak out of the eigenmodes.

I've put these into the SUS-PRM MEDM screen.

Attachment 1: PRM_Eigmodes_shihori.png

Attachment 2: PRM_Eigmodes_sonia.png

859

Wed Aug 20 11:50:10 2008

To restart the striptools on op540m:

cd /cvs/cds/caltech/scripts/general/

./startstrip.csh

858

Wed Aug 20 11:42:49 2008

I've installed pdftk on all the control room machines.

http://www.pdfhacks.com/pdftk/

857

Tue Aug 19 19:14:17 2008

DAQ

Fixed C1:IOO-MC_RFAMPDDC

Yoichi, Rob

C1:IOO-MC_RFAMPDDC, which is a PD at the transmission port of the MC, was not recording sensible values.
So I tracked down the problem starting from the centering of the beam on the PD.
The beam was hitting the PD properly. The DC output BNC on the PD provided +1.25V output when the light was
falling on the PD. The PD is fine.
The flat cable from the PD runs to the IOO rack and fed into the LSC PD interface card.
The output from the interface card is connected to a VMIC3113A DAQ card, through cross connects.
The voltages on the cross connects were ok.
The VMIC3113A was controlled by an EPICS machine (c1iool0). So it provides only a slow channel.
By looking at C1IOOF.ini and tpchn_C1.par, I figured that C1:IOO-MC_RFAMPDDC is using chnnum=13639 in the RFM
network and it is named C1:IOO-ICS_CHAN_15 in the .par file. So it is reading values from the ICS DAQ board.
Actually nothing was connected to the channel 15 of the ICS board and that was why C1:IOO-MC_RFAMPDDC was reading
nothing. So I took the PD signal from the cross connect and hooked it up to the Ch15 of the ICS DAQ through
the large black break out box with 4-pin LEMOs. Now C1:IOO-MC_RFAMPDDC reads the DC output of the PD.
I also put an ND filter in front of the RFAMPD to avoid the saturation of the ADC. The attenuation should have been done
electronically, but I was too lazy. Since the ND filter changes the Stochmon values, someone should remove it and reduce the
gain of the LSC PD interface accordingly.

856

Tue Aug 19 18:55:41 2008

IOO

MC unlock study update

In entry 849, I reported that the MC transmitted power drops before the sudden unlocks.
However, because C1:IOO-MC_TRANS_SUM is a slow channel, we were not sure if we can believe the timing.
So I wanted to use C1:IOO-MC_RFAMPDDC, which is a fast channel, to monitor the transmitted light power.
However, this channel was broken. So I fixed it. Details of the fixing work is reported in another entry.
The attached plot shows a recent unlock event. It is clear that in the fast channel (i.e. C1:IOO-MC_RFAMPDDC),
there is no delay between the drop of the MC power and the crazy behavior of control signals.
So it was concluded that the apparent precedence of the MC power drop in the slow channels (i.e. C1:IOO-MC_TRANS_SUM)
is just an artifact of timing inaccuracy/offset of the slow epics channels.

Sometime around 5PM, the MC started to be unwilling to even lock. It turned out that the PC drive of the FSS was going
crazy continuously. So I changed the normal values of the common gain and the fast gain, which the mcup script uses.
Now with this new setting, the MC locks happily, but still keeps unlocking.

Attachment 1: MC-unlock.png

855

Tue Aug 19 17:15:34 2008

MEDM

I plugged in the gains I got for the accelerometers in the accelerometers' filters in the PEM screen of the adaptive filter

854

Tue Aug 19 17:00:19 2008

Wiener TF calibration - update

This is an update for post 814

I added the calibration gains I got for the accelerometers (I realize I am just calibrating the accelerometers to themselves and this is not m/m exactly since we don't really know which accelerometer is doing exactly what we want it to do. However, since we are talking on relative small numbers, this shouldn't really change much).

I also added another missing gain for the seismometer. Rana has previously installed a 4300 ohm resistor in the seismometer, which changed the gain to 4300/(4300+5000) = 0.46 (this is from the manual). Moreover, there is a gain of 100 on the SR560. This comes up to an extra gain of 46, meaning multiplying the seismometer's counts by 1/46.

Attachment 1: m_per_m.png

853

Tue Aug 19 14:25:38 2008

Accelerometer's calibration - update

Goal - Make sure the accelerometers are calibrated among themselves (have the same power spectrum when they are all together reading the same movements).

What I did - took the accelerometers off their usual X Y Z setting and set the 3 MC2's and 3 MC1's next to each other covered by a box.
Then I brought MC2 X to MC1 X and placed them in a box so I have a referance between the 2 groups.

Result - Seems MC1 accelerometers are much alike and have the same power spectrum when placed together for all frequencies. MC2 accelerometers seem to do the same until approximately 30 Hz. (decided not to correct for that since we don't really care about the accelerometers in such high frequencies).

When comparing the 2 X's, they also seemed to be almost perfectly correlated. I chose the gain by dividing the two and finding the mean of that in the range of 2 to 30 Hz. After correcting for all the accelerometers, I matched the gains of each group to its X accelerometer.

You can see the plots, taking into consideration that the groups were never together (pretty messy getting the cables all around).

Here are the numbers, when the MC2 and MC1 gains are calculated by comparing them to their X direction.

gain MC1 X_over_MC2 X=

1.0870

gain_MC2_Y =

0.9944

gain_MC2_Z =

0.9479

gain_MC1_Y =

1.0394

gain_MC1_Z =

0.9149

Attachment 1: acccalibafter.png

Attachment 2: acccalibbefore.png

852

Tue Aug 19 13:34:58 2008

Switched c1pem1, c0daqawg, c0daqctrl over to new switches

Moved the Ethernet connections for c1pem1, c0daqawg, and c0daqctrl over to the Netgear Prosafe switch in 1Y6, using new cat6 cables.

851

Tue Aug 19 13:12:55 2008

Diagonalized PRM Input Matrix

NOTE: Use the values in elog #860 instead (20Aug2008)

Using the method described in LIGO-T040054-03-R (Shihori's "Diagonalization of the Input Matrix of the Suspension System"), I have diagonalized the input matrices for the PRM.

Notes about the method in the document:

Must define the peak-to-peak voltage (measured via DataViewer) to be NEGATIVE for PitLR, PitLL, YawUR, YawLR, and POSITIVE for all others
As Osamu noted in his 3 Aug 2005 elog entry, all of the negative signs in equations 4-9 should all be plus.

New PRM Input Matrices:

	POS	PIT	YAW
UL	1.000	1.000	1.000
UR	1.1877	1.0075	-1.0135
LR	0.8439	-0.9425	-0.9653
LL	0.9684	-1.0500	1.0216

850

Tue Aug 19 10:36:34 2008

Calibrating accelerometers

I took apart the accelerometers near MC1 and MC2.
The 2 sets of 3 accelerometers are now covered by a box on the floor. Please try not to move them... I will place it all back once I am done calibrating.

849

Mon Aug 18 22:47:12 2008

As rob noted, the MC keeps unlocking in a few minutes period.
I plotted time series of several signals before unlocks.
It looks like the MC alignment goes wrong a few hundred msec before the unlock (the attached plot is only one example, but all unlocks
I've looked so far show the same behavior).
I will look for the cause of this tomorrow.

The horizontal axis of the plot is sec. The data values are scaled and offset-removed appropriately so that all curves are shown
in a single plot. Therefore, the vertical axis is in arbitrary units.

Attachment 1: MC-Unlock.png

848

Mon Aug 18 17:37:14 2008

I removed the beam block after the PSL periscope and opened the PSL shutter.

There was no MC Refl beam on the camera, so I decided to trust the PSL launch
and aligned the MC to the PSL beam. Here are the old and new values for
the MC angle biases:

 __Epics_Channel_Name______   __OLD_____    ___New___
 C1:SUS-MC1_PIT_COMM          4.490900        3.246900 
 C1:SUS-MC1_YAW_COMM          0.105500	      -0.912500
 C1:SUS-MC2_PIT_COMM          3.809700	      3.658600 
 C1:SUS-MC2_YAW_COMM          -1.837100	      -1.217100
 C1:SUS-MC3_PIT_COMM          -0.614200	      -0.812200
 C1:SUS-MC3_YAW_COMM          -3.696800	      -3.303800

After this, the beam looks a *little low* going into the Faraday Isolator.
Nonetheless, after turning on the IFO input steering PZTs, I was able to
quickly steer the PRM get a beam on the REFL camera and into the REFL OSA.
The PRM optical lever beam is also striking the quad.

I then used the ETMX optical lever as a reference for realigning. After
steering around the input PZTs and ITMX, I saw some flashes in Xarm trans, then got
it locked and ran the alignment script ~5 times. The arm power went
up to 0.9, so I tweaked the MC1 to put the MC refl beam back on MCWFS.
The XARM power then went up to .96. Good enough for now.

Then I started to try and re-align the YARM. Since the oplevs for both ITMY
and the BS are untrustworthy, I first tried to get the beam bouncing off ITMX
and the BS back into the AS OSA, to try and recover some BS alignment. This
didn't work, as the AS OSA may not be a good reference anyways. After
wandering around in the dark for a little while, I decided to try an automated
scan of the alignment space. I used the trianglewave script to scan
the angle biases of BS, ITMY, & ETMY, then looked at the trend of the transmitted
power to find the gps time when there were flashes. I then used
time_machine_conlog to restore the biases to that time. This was close
enough to easily recover the alignment. After several rounds of aligning &
centering oplevs, things look good.

Also locked a PRM. Will work on the DRM tomorrow.

I'm leaving the optics in their "aligned" states over night, so they can
start their "training."

Note: The MC is not staying locked. Needs investigation.

For tomorrow:

lock up the DRM
fix the mode cleaner
re-align mode cleaner to optimize beam through Faraday
re-align all optics again (will be much easier than today)
re-align beam onto all PDs after good alignment of suspended optics is established.

Attachment 1: flatlissa.png

847

Mon Aug 18 15:32:18 2008

How to multicast with gstreamer and Gige Cameras

In order to get multicasting to work, one simply needs to understand the address scheme.

In general, the address range 224.0.0.0 - 239.255.255.255 are reserved for multicasting. Within in this address space, there are some base level operations in the 224.0.0.x range which shouldn't be interfered with.

For a single site, the address range between 239.252.0.0 and 239.255.255.255 is probably best.

Gstreamer and the current 40m network hubs are designed to handle this kind of communication already, so one merely needs to point them at the correct addresses.

While in /cvs/cds/caltech/target/Prosilica/40mCode/SnapCode type:

CamServe -F 'Mono8' -c 44058 -E 20000 -X 0 -Y 0 -H 480 -W 752 -l 0 -m 300 | gst-launch-0.10 fdsrc fd=0 blocksize=360960 ! video/x-raw-gray, height=480, width=752, bpp=8,depth=8,framerate=60/1 ! ffmpegcolorspace ! queue ! smokeenc keyframe=8 qmax=40 ! udpsink host=239.255.1.1 port=5000

This will multicast to the 239.255.1.1 address, using port 5000.

On the machine you wish to subscribe type:

gst-launch udpsrc multicast-group=239.255.1.1 port=5000 ! smokedec ! ffmpegcolorspace ! ximagesink sync=false

846

Mon Aug 18 11:50:29 2008

In vacuum free swinging results

The first attachment is the results of the free swinging spectra measurement performed in vacuum this morning.
They are freely swinging, but the suspensions in the BS chamber got even more extra peaks.
Especially, the SRM spectrum looks like a forest.
If those extra peaks are inter-modulations of the primary suspension modes, the heights of them should be
enhanced (compared to the in-the-air case) by the increased quality factors of the primary modes (due to the less air friction).
This might explain the observed increase in the extra peaks.

While doing the free swinging, we had two big spikes in the OSEM signals of the ETMs and only in ETMs.
Those spikes screwed up the spectra of the ETMs. So the ETM spectra were calculated using the time series
after the spikes.
The second attachment shows one of those spikes. It looks like a computer glitch.

Attachment 1: 2008-8-18.pdf

Attachment 2: spike.pdf

845

Mon Aug 18 09:19:55 2008

It took 11 days to fix earth quake triggered sus problems of ITMX, SRM and PRM
Only ITMX north and BSC north vac doors were removed.

The PRM sus had to be removed form the vac envelope for "hip replacement"-new wire stand off was
epoxied in place.
Note: the PRM has no guide rod on the other side

ITMX, SRM and BS osems were optimized in place.
No crosscoupling optimization was performed.
Beam block was removed from ITMXC, it was too close to the main beam.

POX pick off mirror and mount will be replaced next vent.

Vac viewports were inspected from the inside.

Attachment 1: ventprm.jpg

844

Mon Aug 18 08:07:10 2008

Suspension free swinging

I've started a free swinging measurement of OSEM spectra now. Please leave the watchdogs untouched.

843

Fri Aug 15 19:32:49 2008

I have just reached vacuum normal. The maglev peaked at 49.8C body temp with aux fan on at 3.2 Torr
cc1 1e-4Torr

note: pumpdown was put on hold for Koji's goodby lunch

Attachment 1: pdprm.jpg

842

Fri Aug 15 17:38:41 2008

OSEM free swinging spectra before the pump down

I ran an overnight measurement of the free swinging OSEM spectra.
The attm1 shows the results. Everything look ok except for the ITMY UL OSEM.
The time series from that OSEM was very noisy and had many spikes.
We suspected the cable from the satellite box to the computer rack because we disconnected the cable
when we tested a spare cable which was used to connect the spare OSEMs to the PRM suspension in the clean room.
Janne remembered when she put the cable back, she trusted the latch on the connector and did not push it in too hard.
However, Rob suggested the latch does not work well. So she pushed the connector again. Then the signal from
the ITMY UL OSEM got back to normal.
The second attachment shows the ITMY spectra after the cable push.
We decided to pump down after confirming this.

There are still a lot of extra peaks especially in the suspensions in the BS chamber.
These may be inter modulations (by the non-linearities of the OSEMs) of the modes of the multiple
suspensions sitting on the same stack.

Attachment 1: 2008-8-15.pdf

Attachment 2: ITMY2.pdf

841

Fri Aug 15 16:45:43 2008

Converting from FIR to IIR

I have been looking into different techniques to convert from FIR to IIR. This is so we can see how effective the adaptive FIR filter is in comparison to an IIR one with fewer taps.
For now I tried 2 matlab functions: Prony and stmcb (which works on LMS method).
I used the FIR wiener code, MC1_X, (c1wino) and applied the FIR to IIR algorithm.
Seems like the stmcb one works a bit better, and that there isn't much effect for having 1000 and not 400 taps.

Will keep updating on more results I have, and hopefully have the MC in time to actually check this live.

Attachment 1: fir2iir50.png

Attachment 2: fir2iir400.png

Attachment 3: fir2iir1000.png

840

Fri Aug 15 14:12:31 2008

Bureaucracy

SAFETY

safety glasses required

The MOPA shutter is opened,
the PSL enclosure is switched to bypass mode,
manual block removed from PMC,

the PSL output is still blocked and the mechanical shutter is still closed.

Pumpdown is at 300 Torr continuing

Laser safety glasses are required!

839

Fri Aug 15 11:52:32 2008

Multi-computer display and recording of digital camera output

Through the magic of gstreamer, I've been able to live play on one machine, compress the image, send it to another machine via udp, and also display it there. The "tee" function also allows one to save at the same images at time as well.

The command line used on the "server", say Rosalba or Mafalda is:

CamServe -F 'Mono8' -c 44058 -E 20000 -X 0 -Y 0 -H 480 -W 752 -l 0 -m 100 | gst-launch-0.10 fdsrc fd=0 blocksize=360960 ! video/x-raw-gray, height=480, width=752, bpp=8,depth=8,framerate=60/1 ! tee name=t1 t1. ! video/x-raw-gray, height=480, width=752, bpp=8,depth=8,framerate=60/1 ! ffmpegcolorspace ! ximagesink t1. ! video/x-raw-gray, height=480, width=752, bpp=8,depth=8,framerate=60/1 ! ffmpegcolorspace ! queue ! smokeenc keyframe=8 qmax=40 ! udpsink host="131.215.113.103" port=5000

This both displays the image and sends it to the host 131.215.113.103 in this case.

I've written a primitive shell script that does most of this.

It requires at the minimum an IP address. You can also give it a number of images (the -m number) and also the exposure value (-E 20000).

Currently in /cvs/cds/caltech/target/Prosilica/40mCode/SnapCode/ there is a script called CameraServerScript.

Typing in "CameraServerScript 131.215.113.107" would send it to that IP address.

Typing in "CameraServerScript 131.215.113.107 500 40000" would run for 500 images at an exposure value of 40000.

To actually receive, you need gstreamer installed and run the following command:

gst-launch udpsrc port=5000 ! smokedec ! queue ! ffmpegcolorspace ! ximagesink sync=false

Make sure you have the right IP address to send to.

Still working on multicasting (basically a server is constantly sending out images, and the client subscribes to the multicast).

838

Thu Aug 14 21:52:51 2008

Koji

Abs. Len. Meas. ~ summary of my Summer

General

I have made the summary of the absolute length measurement.
It is attached here. The file is a bit big (~8.6MB).

Attachment 1: mode_spacing_measurement_080816_v2.pdf

837

Thu Aug 14 19:35:54 2008

PRM in the chamber, ready to pump!

IOO

Rob, Yoichi, Jenne, Steve

Summary: Everything is back in the chamber, we just need to put on the big doors, and start pumping in the morning.

After letting the PRM's standoff epoxy cure overnight, it was time to put the optic back in the BS Chamber. Rob put the optic cage back in the chamber, as close to the guide points that Rana had placed as possible. A handy technique was discovered for pushing the cage into place: put a long screw into the table, leaving an inch or so above the table, then use that as a push-off point so that you can push the base of the cage with your thumb. According to Rob, this is probably just about as effective as using a pusher-screw.

The guides were helpful in getting the PRM back to its original position, but one of them was placed in such a way that it could move when pushed against. The clamp that was used as a guide point was placed with one of the screws half on the edge of a hole, so that when the cage was pushed against the guide point, that screw could wiggle around, causing the clamp to rotate thus no longer being a definite guide point.

Just after putting the PRM in place, Rob found the standoff that had gone missing. (see elog #835)

Once the PRM was back in place, we put the OSEMs back, and reinstalled the satellite boxes that had been removed (PRM's, which Ben has fixed - an op-amp was blown, and BS's, which we used over in the clean room with the spare OSEMs). We found a problem with the LR PRM OSEM reading on Dataviewer. It was saturating when the OSEM was just sitting on the table, with nothing between the LED and the sensor. We measured the output from the satellite box with the octopus cables, and measured 2.3 volts, which is too much for the DAQ. It seems fine when we install it in the cage, and the magnet is blocking part of the light. We should investigate the gain of the satellite box when convenient. This is not something that needs to be done prior to pump-down. Also, when we put an allen wrench to block the light while checking which OSEM was which, we noticed that the Dataviewer reading would go down to -2V, then come back to 0V when the light was completely blocked. This may be some incorrect compensation for some whitening. Again, we should look into this, but it is not terribly time-sensitive.

Once the OSEMs were centered, we tried to turn on the damping for the PRM. This was successful, so we are confident that we have put all of the OSEMs back in their correct places.

We found that we were easily able to get the PRM's oplev back on the QPD, so we ~centered the oplev, and then centered all of the PRM's OSEMs. This assumes that the oplev was in a good place, but I think we've determined that this is the case.

We did the same thing for the SRM and the BS, to check the OSEM values before we close up for good. We found that some of the SRM OSEMs were reading low (magnet too far in), and that all of the BS OSEMs were low, perhaps as if the table were tilted a tiny bit after removing and replacing the weight of the PRM. We recentered all of the OSEMs for both of these optics.

We checked that all of the pigtails for the PRM OSEMs were anchored to the PRM cage using some copper wire as tie-downs.

We checked that all of the earthquake stops were within 1mm or so of each of the 3 optics in the BS chamber. The SRM's earthquake stops were fairly far out. One of the bottom ones was far enough that when Yoichi turned it the wrong way (accidentally), it fell out. He put it back in, and adjusted all of the earthquake stops appropriately. This 1mm distance comes from Seji, and the specs for the optics' cages.

We did a look-through of the chamber, and took out all of the tools, and other things that were not bolted down to the table.

We have left the damping of the PRM off for the night.

To do: put the doors back on, and start the pump down.

836

Thu Aug 14 19:08:14 2008

Free swing measurement going on

I started free swinging spectra measurement of all the suspensions now Aug 14 19:05 (PDT).
The watch dogs are all shutdown. Please do not turn them back on until tomorrow morning.

835

Thu Aug 14 15:51:35 2008

FOUND! The Missing Standoff!

We used a zoom lens on the GC750 to take this picture of the standoff while inside a plastic rubber-glove bag. The standoff with bag is currently scotch-taped to the periodic table of the elements.

Attachment 1: standoff.png

834

Thu Aug 14 11:39:06 2008

particle counter is out of order

The 40m ifo paricle counter sensor failed last night.

833

Thu Aug 14 10:26:45 2008

HowTo

sus cable pin cheater for out of vac damping

The 40m D25 vacuum feed troughs give you a mirror image pin count.

Sus damping outside of the vacuum envelope require this cheater cable where
on the male D pin 1 is connected to female D 13 and so on
and male D pin 14 is connected to female D 25 and so on

Attachment 1: suscabmin.png

832

Wed Aug 13 20:13:35 2008

PRM stand-off is glued

Steve, Janne, Rob, Bob, Koji, Yoichi

We finally managed to balance the PRM and the stand-off is now glued.

The whole procedure was something like this:

(1) Measure the levelness of the optical table. It was done by a bubble level claiming that
the sensitivity is 60 arcsec (roughly 0.3 mrad).
There was no noticeable tilt along the longitudinal direction of the table.

(2) We put a He-Ne laser on one end of the table. Mounted a QPD on a X-Y-Z stage. Put the QPD very
close to the laser and centered it by moving the QPD.
Then we moved the QPD far away from the laser and centered the beam spot in vertical direction
by changing the tilt of the laser mount.
We then moved the QPD close to the laser again and adjusted the height to center it. By repeating
the centering at two locations (near and far) several times, we aligned the laser beam parallel to
the table.

(3) The PRM suspension tower was put on the other end of the optical table, i.e. far from the laser.
The QPD was moved next to the laser to form an optical lever. The height of the QPD is preserved from
the previous step.

(4) A stand-off was picked by a pair of tweezers. By gently lifting the mirror by the bottom earthquake stops,
the tension of the wire was relieved. Then the stand off was slid in below the guide rod.

(5) Using the microscope, it was confirmed that the wire is in the grooves on both sides.

(6) Without damping, it was too much pain to balance the mirror. So we put spare OSEMs in the suspension and
pulled a long cable from the suspension rack to the clean room with a satellite amp.

(7) It turned out that the pinout of the cable is flipped because of the vacuum feed through. So we asked Ben for help.
He made conversion cables. We also found UR OSEM was not responding. Ben opened the satellite box, and we found an op-amp was burnt.
Probably it was because we connected OSEMs wrongly at first and the LED current driver was shorted. We switched the satellite box
from the PRM one to the BS one. Ben will fix the PRM box.
Bob cleaned up some D-Sub converters for the interface with the clean OSEM pigtails.

(8) While waiting for Ben, we also tried to short the OSEM coils for inductive damping. We saw no noticeable change in the Q.

(9) After the OSEMs were connected to the digital control system, Rob tweaked the damping gains a bit to make it work efficiently.

(10) I pushed the stand-off back and forth to make the reflected beam spot centered on the QPD. I used the PZT buzzer to gently move the stand-off.
For fine tune, just touching it is enough. I found it useful to touch it without clamping the mirror, because if it is clamped, we can easily push
it too hard. When the mirror is freely hanging, once the tip of the buzzer touches the stand-off, the mirror escapes immediately. If the mirror
swings wildly by your touch, you pushed it too hard.

(11) After about an hour of struggle, I was able to level the mirror. We used about 1.5m optical lever arm. A rough calibration tells us that the
beam spot is within 0.6mm of the center of the QPD. So the reflected light is deflected by 0.4mrad. That means the mirror
is rotated by 0.2mrad. The OSEMs should have about 30mrad of actuation range. So this should be fine.

(12) We mixed the Vac Seal epoxy and put it under vacuum for 15min to remove bubbles. Actually 15min was not enough for removing bubbles completely. But
stopped there because we did not want the epoxy to be too stiff.
I dipped a thin copper wire into the epoxy and applied it on the top of the stand-off. I found the epoxy is already not fluid enough, so Steve made
another Vac Seal mixture. This time we put it under vacuum for only 3 min.
I also applied the epoxy to the sides of the stand-off.
While working on this, I accidentally touched the side of the PRM. Now there is a drop of epoxy sitting there (upper left of the attached picture).
We decided not to wipe it out because we did not want to screw up the levelness.

(13) We put an incandescent light about 1m away from the suspension to gently warm up the epoxy but not too much. We will leave it overnight to cure the
epoxy.

Attachment 1: img1.jpg

831

Wed Aug 13 17:00:59 2008

The PRM sat amp is broken. Ben is working on it.
The BS sat amp was removed from the BS sus and it is used with the PRM in
order to damp it for wire stand-off alignment.

830

Tue Aug 12 21:38:19 2008

John

Accidental higher order mode resonances in the arms

LSC

Recently we had been having some trouble locking the full IFO in the spring configuration (SRC on +166).
It was thought that an accidental higher order mode resonance in the arms may have been causing problems.

I previously calculated the locations of the resonances using rough arm cavity parameters(Elog #690). Thanks to Koji
and Alberto I have been able to update this work with measured arm length and g factors for the y arm (Elog #801,#802).
I have also included the splitting of the modes caused by the astigmatic ETM. Code is attached.

I don't see any evidence of +166MHz resonances in the y arm.

In the attached plot different colours denote different frequencies +33, -33, +166, -166 & CR.
The numbers above each line are the mn of TEMmn.
Solid black line is the carrier resonance.

Attachment 1: HOMresonances.png

Attachment 2: HOMarms2.m

%Check for accidental resonances of HOM in the arms (maybe due to
%sidebands). At the moment there is only data for the y arm.

clear all
close all
clc


%Stuff one might change often
modeorder = 0:5;          % Look for TEMmn modes where m,n run over modeorder

... 157 more lines ...

829

Tue Aug 12 19:48:24 2008

PRM standoff is in....mostly

IOO

Yoichi, Jenne

The missing PRM standoff is now partially installed. The standoff is in, and the wire is in the groove, but we have not finished adjusting its position to make the PRM stand up straight. It turns out to be pretty tricky to get the position of the standoff just right.

We have set up a HeNe laser as an oplev on the flow bench (which we checked was level) in the clean assembly room, and are using it to check the pitch of the mirror. We set a QPD at the height of the laser, and are looking at the single-reflected light. When the single-reflected light is at the same height as the center of the QPD, then the mirror is correctly aligned in pitch. (Actually, right now we're just trying to get the single-reflected light to hit the diode at all...one step at a time here).

We'll continue trying to align the PRM's standoff in the morning.

828

Tue Aug 12 12:21:13 2008

Variation in fit over 140 images for GC650 and GC750

Used matlab to calculate Gaussian fits on 145 GC650 images and 142 GC750 images. These were individual images (no averaging) looking at the PSL output from May 29th 2008. The GC650 and GC750 were looking at a split, but had different exposure values, slightly different distances to the nominal waist of the beam, and were not centered on the beam identically. Mostly this is a test of the fluctuations in the fit from image to image.

Note the mm refer to the size or position on the CCD or CMOS detector itself.

GC650

Mean
Amplitude  X center       Y center       X waist  Y waist  Background offset from zero
           position (mm)  position (mm)  (mm)     (mm)
0.3743     1.7378         2.6220         0.7901   0.8650  0.0047

Standard Deviation
Amplitude  X center       Y center       X waist  Y waist  Background offset from zero
           position (mm)  position (mm)  (mm)     (mm)
0.0024     0.0006         0.0005         0.0005   0.0003  0.00001

Std/Mean x100 (percent)
Amplitude  X center       Y center       X waist  Y waist  Background offset from zero
           position (mm)  position (mm)  (mm)     (mm)
0.6%       0.03%          0.02%          0.06%    0.04%    0.29%


GC750

Mean
Amplitude  X center       Y center       X waist  Y waist  Background offset from zero
           position (mm)  position (mm)  (mm)     (mm)
0.2024     2.5967         1.4458         0.8245   0.9194  0.0418

Standard Deviation
Amplitude  X center       Y center       X waist  Y waist  Background offset from zero
           position (mm)  position (mm)  (mm)     (mm)
0.0011     0.0005         0.0005         0.0003   0.0005  0.00003

Std/Mean x100 (percent)
Amplitude  X center       Y center       X waist  Y waist  Background offset from zero
           position (mm)  position (mm)  (mm)     (mm)
0.6%       0.02%          0.04%          0.04%    0.05%    0.07%

827

Tue Aug 12 12:05:36 2008

HP color printer is back

I restarted the HP printer server (a little box connected to the HP color laser) so that we can use the HP LaserJet 2550.
After this treatment, the printer spat out a bunch of pages from suspended jobs, many of these were black and white.
I think people should use the black-and-white printer for these kind of jobs, because the color printer is slow and troublesome.

826

Mon Aug 11 19:09:28 2008

DAQ

Seismometer DAQ is being funny

While looking at the Ranger seismometer's output to figure out what our max typical ground motion is, Rana and I saw that the DAQ output is at a weird level. It looks like even though the input to the DAQ channel is being saturated, the channel isn't outputing as many counts as expected to Dataviewer.

Sharon and I checked that the output of the seismometer looks reasonable - sinusoidal when I tap on the seismometer, and the the output of the SR560 (preamp) is also fine, and not clipping. If I stomp on the floor, the output of the SR560 goes above 2V (to about 3V ish), so we should be saturating the DAQ, and getting the max number of counts out. However, as you can see in the first figure, taken when I was tapping the seismometer, the number of counts at saturation is well beneath 32768counts. (16 bit machine, so the +-2V of the DAQ should have a total range of 65536. +2V should correspond to +32768counts.) The second figure shows 40 days of seismometer data. It looks like we saturate the DAQ regularly.

I did a check of the DAQ using an HP6236B power supply. I sent in 1V, 2V and 2.2V (measuring the output of the power supply with a 'scope), and measured the number of counts output on the DAQ.

Input Voltage [V]	Counts on Dataviewer	Expected counts from 16 bit machine
1	18983	16384
2	29331	32768
2.2	29347	32768

I'm not sure why the +1V output more than the expected number of counts (unless I mis-measured the output from the power supply).

Moral of the story is...when the DAQ is saturated, it is not outputting the expected number of counts. To be explored further tomorrow...

Attachment 1: SeisDAQ.png

Attachment 2: SeisData.png

825

Mon Aug 11 15:07:49 2008

Procyon aka fb40m switched to new switch

I've connected Procyon to the Prosafe 24 port switch with a new, labeled Cat6 cable. Quick tests with dataviewer shows that its working.

824

Mon Aug 11 13:59:23 2008

While poking around the crate, I noticed an error light on one of the c1susvme2 related boards was lit, while the corresponding light on the c1susvme1 was not. This confuses me as the c1susvme1 is the one having problems.

As a quick sanity check, I unplugged the ethernet connection from the c1susvme1 labeled board, and confirmed I couldn't log into it, and then plugged it back in, restarted it, and re-ran the startup script. This time c1susvme1 seemed to come up fine. Re-enabling the watchdogs doesn't seem to kick anything, and in fact seems to be bringing everything into line properly.

Although the error light on the c1susvme2 clk drvr board is still on. So I'm not sure what thats trying to tell us. Open to suggestions.

823

Mon Aug 11 12:42:04 2008

Continuing saga of c1susvme1

Coming back after lunch around 12:30pm, c1susvme1's status was again red. After switching off watchdogs, a reboot (ssh, su, reboot) and restarting startup.cmd, c1susvme1 is still reporting a max sync value (16384), occassionally dropping down to about 16377. The error light cycles between green and red as well.

At this point, I'm under the impression further reboots are not going to solve the problem.

Currently leaving the watchdogs associated with c1susvme1 off for the moment, at least until I get an idea of how to proceed.

822

Mon Aug 11 11:36:11 2008

josephb, Steve

c1susvme1 minor problems

Around 11 am c1susvme1 start having issues. Namely C1:SUS-PRM_FE_SYNC was railing at some large value like 16384 (2^14). I presume this means the computer was running catastophically late.

I turned off the BS and ITM watch dogs (the PRM was already off), tried hitting reset and sshing in, and running startup, but this didn't help. I then turned off the c1susvme2 associated watch dogs (MC1-3, SRM) and went out to do a hard reboot by switching the crate power off. c1susvme2 came back up fine, was restarted and associated watch dogs turned back on. However, c1susvme1 came back up without mounting /cvs/cds/.

As a test, I replaced the ethernet connection with a CAT6 cable to the Prosafe switch in 1Y6, and then ran reboot on c1susvme1. When it came back up, it had mounted properly, and I was able to run the ./startup.cmd file. At this point it seems to be happy. The new cable is in the trays coming in from the top of the 1Y4 and 1Y6 and approriately labeled.

Edit: Apparently ITMX and ITMY became excited after the reboot (perhaps I turned the watchdogs back on too early? Although that was after the DAQ light was listed as green for c1susvme). Steve noticed this when the alarms went off again (I had turned them off after the reboot seemed successful), and he damped them. Interestingly, the BS remained unexcited.

821

Mon Aug 11 09:39:29 2008

rana

2 years of temperature trend

Steve and I went around and inspected and then adjusted the thermostats and humidostats.

All the thermostats were set at 70F in 2005 by Steve. We adjusted the ones on the arms up to 72F
and set the one on the wall west of the framebuilder up to 74F (this area was consistently colder
than all the others and so we're over-correcting intentionally).

820

Mon Aug 11 00:58:31 2008

rana

2 years of temperature trend

The PSL RMTEMP alarmed again because it says the room temperature is 19.5 C. Steve said in
an earlier log entry that this is a false alarm but he didn't say why he thought so...

I say that either the calibration of the RMTEMP channel has drifted, the setpoint of the HVAC
has shifted, or there's a drift in the RMTEMP channel. I don't know what electronics exactly
are used for this channel so not sure if its susceptible to so much drift.

However, since the Dust Monitor (count_temp) shows a similar temperature decline in the
last two years I am inclined to blame the HVAC system.

The attached plot shows 2 years of hour-mean trend.

Attachment 1: Untitled.png

819

Sun Aug 10 16:57:02 2008

rana

Photos from Vent 8/4 - 8/8

Photos

http://www.ligo.caltech.edu/~rana/40m/VentAug08/

I've added the D40 pictures from last week to this web page. I have done some cropping and
rotating to make things look better.

On page 3, there are some over head shots of the Michelson area so that one can use screw holes
to judge what the spacing between the suspensions is and also possibly the cavity lengths. Lets
also remember to measure the ITM-BS distance accurately using a tape measure or ruler while we
have the thing open.

818

Fri Aug 8 17:54:52 2008

Standoffs and Guide Rods

After closer inspection of other small optics, it is clear that the guide rods should be above the standoffs on our small optics. Yoichi took a picture of the SRM that shows this clearly. This makes sense since the tension of the wire will make the standoff 'want' to go up during pre-epoxy adjustment, so the guide rod prevents the standoff from popping up and out.

Looking at the side of the PRM without the groove, it looks like there is lots of space between the guide rod and the alignment etch in the glass, so we can just place a standoff directly under the guide rod that is present.

A spare standoff is being shipped tomorrow morning, so we should have it by Monday for installation on the PRM.

Attachment 1: SRM_Standoff_and_guide.JPG

817

Fri Aug 8 15:10:35 2008