you asked for: diff 2008/07/21,13:00 2008/07/22,2:44:16 utc '.*FSS.*|.*MC.*'
LIGO controls: differences, 2008 07/21 13:00:00 utc vs. 2008 07/22 02:44:16 utc
__Epics_Channel_Name______ __Description__________ __value1____ __value2____
C1:IOO-MC_REFL_GAIN 22.000000 19.000000
C1:IOO-MC_REFL_OFFSET 0.818380 0.818100
C1:PSL-FSS_MGAIN 10.000000 30.000000
C1:PSL-FSS_PHCON 2.073170 1.413170
27.0924 27.0934 [m]
I was notified by Rob and Rana that there were many measurements of the MC abs length (i.e. modulation
frequencies for the IFO.) between 2002 and now.
So, I dig the new and old e-logs and collected the measured values of the MC length, as shown below.
I checked the presence of the vent for two big steps in the MC length. Each actually has a vent.
The elog said that the tilt of the table was changed at the OMC installation in 2006 Oct.
It is told that the MC mirrors were moved a lot during the vent in 2007 Nov.
o The current modulation freq setting is the highest ever.
o Rob commented that the Marconi may drift in a long time.
o Apparently we need another measurement as we had the big earthquake.
My curiosity is now satified so far.
Local Time 3xFSR[MHz] 5xFSR[MHz] MC round trip[m] Measured by
2002/09/12 33.195400 165.977000 27.09343 Osamu
2002/10/16 33.194871 165.974355 27.09387 Osamu
2003/10/10 33.194929 165.974645 27.09382 Osamu
2004/12/14 33.194609 165.973045 27.09408 Osamu
2005/02/11 33.195123 165.975615 27.09366 Osamu
2005/02/14 33.195152 165.975760 27.09364 Osamu
2006/08/08 33.194700 165.973500 27.09401 Sam
2006/09/07 33.194490 165.972450 27.09418 Sam/Rana
2006/09/08 33.194550 165.972750 27.09413 Sam/Rana
----2006/10 VENT OMC installation
2006/10/26 33.192985 165.964925 27.09541 Kirk/Sam
2006/10/27 33.192955 165.964775 27.09543 Kirk/Sam
2007/01/17 33.192833 165.964165 27.09553 Tobin/Kirk
2007/08/29 33.192120 165.960600 27.09611 Keita/Andrey/Rana
----2007/11 VENT Cleaning of the MC mirrors
2007/11/06 33.195439 165.977195 27.09340 Rob/Tobin
2008/07/29 33.196629 165.983145 27.09243 Rob/Yoichi
We centerd the input of WFS QPD.
We found that the MC REFL image was no longer round and that the MCWFS DC quadrant spots were mostly
in one quadrant. So we re-centered the MCWFS beams in the following way:
1) We unlocked the MZ and adjusted the PZT voltage to keep the beam on the WFS from saturating.
2) Re-aligned the black hole beam dump to center its beam in its aperture.
3) centered the beam on the MCWFS optics and MCWFS QPD displays.
4) Relocked MC.
Below is the image of the IOO Strip tool. You can see that the MC REFL DC is now more flat. The
MC pointing has also been changed (see the MC TRANS HOR & VERT channels). The MC transmitted
light is also now more stable and higher.
We tried to center the QPD, and we found that there were a few hundred mV of dark offset for each
quadrant of QPD. We adjusted them with this scripts:
The power supply of a lock-in amp, which is on the Y-arm side of PSL clean room, was pulled out by my mistake.
Then I reconnected it, but I don't know whether it is re-adjusted properly.
I'm sorry about this. If you are using that amp, it should be checked.
On Monday evening, I ran this command: trianglewave C1:IOO-MC_REFL_OFFSET 0 4 120 600;ezcawrite C1:IOO-MC_REFL_OFFSET 1.76
trianglewave C1:IOO-MC_REFL_OFFSET 0 4 120 600;ezcawrite C1:IOO-MC_REFL_OFFSET 1.76
which I thought (from the syntax help) would move that offset slider with a period of 120 seconds for 600 seconds. In actuality, the last argument is the
run time in number of periods. So the offset slider has been changing by 8 Vpp for most of the last day. Oops. The attached image shows what effect
this had in the MC transmitted power (not negligible). This would also make the locking pretty difficult.
In the second plot you can see the zoom in view for ~30 minutes. During the first part, the MCWFS are on and there are large fluctuations
in the transmitted power as the WFS offset changes. This implies that the large TEM00 carrier offset we induce with the slider couples into
the WFS signals because of imbalances in the quadrant gains - we need someone to balance the RF gains in the WFS quadrants by injecting
an AM laser signal and adjusting the digital gains.
Since there is still a modulation of the MC RFPD DC with the WFS on, we can use this to optimize the REFL OFFSET slider. The third plot
shows a 8 minute second trend of this. Looks like the slider offset of zero would be pretty good.
This morning, MC alignment was gone and MC wasn't lock.
We checked old value of pitch, yaw, and position offset of each MC mirror, and found they were jumped.
We don't know the reason of this jump, but we restore each offset value and MC backed to lock.
Kakeru and Kiwamu
We placed a QPD on the PSL bench for PSL angle monitor.
I checked a broken QPD, which was placed for PSL angle monitor, and finally I cocluded one segment of the quadrant diode was broken.
The broken segment has a offset voltage of -0.7V after 1st I-V amplifier. It means the diode segment has a current offset without any injection of light.
Tomorrow I will check a new QPD for replacement.
As we mentioned before, old QPD which used to be placed is broken.
And we put broken QPD into the "photodiodes" box under the soldering table.