 Wed Nov 4 20:16:58 2015, yutaro, Update, Electronics, offset voltage vs. gain of common mode servo
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At 1Y2 rack, I measured offset voltage of the common mode servo (D040180-B) with the gain of it
varied.
For now, all signal cables that come into or go out of the common mode servo are not plugged. |
 Thu Nov 5 10:48:21 2015, yutaro, Update, Electronics, offset voltage vs. gain of common mode servo 
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I report the results of the measurement to know how offset voltage of common mode servo changes when the gain is changed.
- Motivation: If discontinuous change of the offset happens when we change the gain, it could cause saturation somewhere and so make |
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Mon Nov 9 11:34:51 2015, yutaro, Update, LSC, FSR and linewidth measurements with phase tracker
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I fitted the data obtained with the FSR and linewidth measurements and I've got FSR and finesse of y-arm by fitting.
The fitted data and the fitting results are attached.
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Mon Nov 9 14:24:36 2015, yutaro, Update, LSC, FSR and linewidth measurements with phase tracker
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I'd like to add a few calculation results, mode matching ratio for Y arm and modulation depth.
Here I assumed peaks marked in the bottom figure shown in elog 11738 as
resonances of carrier and modulated sidebands and others as resonances of HOM. |
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Tue Nov 10 11:06:02 2015, yutaro, Update, LSC, Updated interpretation of peaks
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Quote:
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Tue Nov 10 16:34:00 2015, yutaro, Update, LSC, Updated interpretation of peaks
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Quote:
What is the uncertainty
of your RoC estimation? |
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Mon Nov 16 11:48:34 2015, yutaro, Update, Optical Levers, Beam centering for the oplev of ETMY
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[yutaro, ericq]
We made the beam spot on QPD for the oplev of ETMY centered by changing the orientation of the mirror just before the QPD. |
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Tue Nov 17 20:40:08 2015, yutaro, Summary, ASC, Loss maps of arm cavities
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In preparation for the measurement of loss maps of arm cavities, I measured the relationship between:
the offset just after the demodulation of dithering loop (C1:ASS-YARM_ETM_PIT_L_DEMOD_I_OFFSET and C1:ASS-YARM_ETM_YAW_L_DEMOD_I_OFFSET)
and |
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Wed Nov 18 11:22:13 2015, yutaro, Update, ASC, Loss maps of arm cavities
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I got linear relation between these. The results and method are below.
Quote:
In preparation for the |
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Wed Nov 18 17:32:36 2015, yutaro, Update, Optical Levers, Beam centering for the oplev of ITMY
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[yutaro, Koji]
We made the beam spot on QPD for
the oplev of ITMY centered by changing the orientation of the mirror just before the QPD. |
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Wed Nov 18 22:26:33 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMY/ETMY
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Based on elog 1403, I calibrated the oplevs for ITMY/ETMY.
Summary of this method is following:
We lock an arm, and slightly misalign one mirror of the arm. Then, the transmission of the arm starts to decrease quadratically as the misalign |
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Thu Nov 19 16:06:54 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMY/ETMY
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I'm sorry. I will be careful about that. And I updated the plots in elog 11785.
Quote:
OMG. Please try to use |
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Tue Nov 24 11:18:47 2015, yutaro, Update, Optical Levers, Beam centering for the oplev of ITMY
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I made the beam spot on QPD for the oplev
of ITMY centered by changing the orientation of the mirror just before the QPD.
Before doing this, I ran dithering |
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Tue Nov 24 14:58:40 2015, yutaro, Update, LSC, ITMX misaligned
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| I misaligned ITMX. The oplev servo for ITMX is now turned off. You can restore ITMX alignment by running "restore". |
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Wed Nov 25 16:40:32 2015, yutaro, Update, LSC, round trip loss of Y arm
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I measured round trip loss of Y arm. The alignment of relevant mirrors was set ideal with dithering (no offset).
Summary:
round trip loss of Y arm: 166.2 +/- 9.3 ppm |
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Wed Nov 25 22:37:12 2015, yutaro, Update, LSC, removal of Gautam's cable in 1Y2 and restoration of POYDC
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[yutaro, Koji]
We disconnected the cable that was connected to CH5 of the whitening filter in 1Y2, then connected POYDC cable to there (CH5). This channel
is where POYDC used to connect. |
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Wed Nov 25 22:59:42 2015, yutaro, Update, LSC, AS table optics realignment
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I slightly changed the orientation of a few mirrors on AS table that are used to make the AS light get into PDs, in order to confirm that
the strange behavior of ASDC (I will report later) is not caused by clipping related to these
mirrors or miscentering on PDs. |
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Wed Nov 25 23:17:34 2015, yutaro, Update, LSC, strange behavior of ASDC
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[yutaro, Koji]
I noticed that ASDC level changes depending on the angle of ITMY when trying to take some data for loss map of YARM. We finally found that
ASDC level behaves strangely when the angle of ITMY in yaw direction is varied, as you can see in Attachment 1. Now, AS port recieved only the reflection |
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Wed Nov 25 23:34:52 2015, yutaro, Update, LSC, round trip loss of Y arm
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[yutaro, Koji]
Due to the strange behavior (elog 11815) of ASDC level, we checked if it is possible
to use POYDC instead of ASDC to measure the power of reflected light of YARM. Attached below is the spectrum of them when the arm is locked. This spectrum |
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Fri Nov 27 03:38:23 2015, yutaro, Summary, LSC, round trip loss of Y arm
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Tonight I measured "loss map" of ETMY. The method to calculate round trip loss is same as written in elog
11810, except that I used POYDC instead of ASDC this time.
How I changed beam spot on ETMY is: elog 11779. |
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Fri Nov 27 22:20:24 2015, yutaro, Update, LSC, round trip loss of Y arm
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Here, I upload data I took last night, including the power of reflected power (locked/misaligned) and transmitted power for each point (attachement 1).
And I would like to write about possible reason why the loss I measured with POYDC and the loss I measured with ASDC are different |
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Sat Nov 28 11:46:40 2015, yutaro, Update, LSC, possible error source of loss map measurement
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I found that TRY level degraded and the beam shape seen with CCD camera at AS port was splitted when the beam spot on ETMY was not close to the center.
This was because dither started not working well. I suspect so because in such a case TRY level went up when I did iteration with
TT1 and TT2 after freezing dither. Splitted beam shape indicates that incident light did not match well with the cavity mode. |
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Mon Nov 30 10:41:45 2015, yutaro, Update, LSC, Does a baffle in front of ETMY have effect on loss map measurement?
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It might have, so I think I need to estimate shift of beam spot more preciely.
According to Steve's drawing, radius of the hole of the baffle is 19.8 mm. |
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Mon Nov 30 12:19:38 2015, yutaro, Update, Computer Scripts / Programs, image capture
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On VIDEO.adl, Image Capture and Video Capture did not seem to work and gave me some errors, so I fixed following two things:
1. just put one side of a USB cable to Pianosa the other side of which was connected to Sensoray; I don't know why but
this was unconnected. |
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Mon Nov 30 17:17:30 2015, yutaro, Update, LSC, Does a baffle in front of ETMY have effect on loss map measurement?
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With captured images of ETMYF, I measured the shift of the beam spot on ETMY.
The conclusions are:
the baffle would have almost no effect on loss map measurement and |
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Tue Dec 1 11:26:23 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMX/ETMX
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With the same method as reported in elog 11785, I calibrated oplevs for ITMX/ETMX.
RESULTS |
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Wed Dec 2 15:52:28 2015, yutaro, Update, LSC, restoration of POXDC
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I disconnected the cable that was connected
to CH6 of the whitening filter in 1Y2, then connected POXDC cable to there (CH6). This channel is where POXDC used to connect.
Then I turned on the whitening |
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Wed Dec 2 17:14:33 2015, yutaro, Update, LSC, Beam on POX11 is possibly not centered well
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I checked how POXDC level changes when the angle of ITMX is varied. ETMX was misaligned.
Then I found that in YAW direction the POXDC level is maximized but it doesnt have plateau, and in PIT direction it is not maximized so that
it is at the slope and it doesnt have plateau, as shown in attached figures. These results indicate that the beam size on POX11 is not small |
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Thu Dec 3 10:05:07 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMX/ETMX
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| I updated the figures. I think it's easier to read now. |
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Thu Dec 3 19:10:28 2015, yutaro, Update, LSC, XARM lock with ITMX actuated and related change on ASS
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To avoid the strange kicking of ETMX, I locked XARM with ITMX actuated instead of ETMX so that I changed elements of C1LSC_OUTPUT_MTRX; before:
XARM=ETMX, after: XARM=ITMX.
And I change C1:LSC-XARM_GAIN from 0.007 to 0.022. |
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Fri Dec 4 10:18:33 2015, yutaro, Update, ASS, Offset in the dither loop of XARM vs beam spot shift on ETMX
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As I did for YARM (elog 11779), I measured the relation between offsets added just after the
demodulation of the dithering loop of XARM and beam spot shift on ETMX. Defferent from YARM, the beam spot on ITMX DOES change because only BS is used
as a steering mirror (TT1&2 are used for the dithering of YARM). Instead, the beam spot on BS DOES NOT change. |
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Fri Dec 4 12:33:52 2015, yutaro, Update, LSC, Beam on POX11 is possibly not centered well
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To focus POX beam on POX11 PD, I added an iris and a lens before POX11 PD as you can see in Attachment 1.
It seemed that the beam is well focused, but the behavior of POXDC has not changed, as shown in Attachments 2 & 3. |
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Fri Dec 4 23:02:13 2015, yutaro, Update, LSC, Beam on POX11 is possibly not centered well
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[yutaro, Koji]
Now, the beam on POX11 PD is well centered and well focused.
We found out why POXDC had behaved as reported in elog 11839. There were a few |
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Sat Dec 5 12:02:25 2015, yutaro, HowTo, Cameras, When image capture does not work...
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Today image capture did not work again, though it had worked 3 days before. I also found that red indicator light on the front pannel of SENSORAY
was not turned on, which had been turned on 3 days before (you can find SENSORAY on the floor near Pianosa). Possible reason that it did not work
again was I restarted Pianosa last night. Anyway, it works now. Here I report what I did to make it work. |
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Sat Dec 5 21:57:32 2015, yutaro, HowTo, Cameras, When image capture does not work...
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I don't know if just running "modprobe" will work or not, because I didn't try it... When the same problem happens again, we
can try just running "modprobe" first. |
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Mon Dec 7 10:40:09 2015, yutaro, Update, Computer Scripts / Programs, Added 1 line to UNFREEZE_DITHER.py
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I added 1 line to one of the ASS scripts, UNFREEZE_DITHER.py like this:
L29> ez.cawrite('C1:ASS-'+dof+'_GAIN', 0)
The reason why I added this is: without this line, C1:ASS-'+dof+'_GAIN become larger |
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Mon Dec 7 11:11:25 2015, yutaro, Summary, LSC, round trip loss of X arm
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On the day before yesterday and in this morning, I measured loss map of ETMX. I reported the method I used to change the beam spot on ETMX below.
Round trip loss was measured for 5 x 5 points. The result is below.
(unit: ppm) |
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Mon Dec 7 15:56:35 2015, yutaro, Update, LSC, XARM lock with ITMX actuated and related change on ASS
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I changed the snapshot file for ASS, /opt/rtcds/caltech/c1/scripts/ASS_DITHER_ON.snap as follows:
L124 > C1:ASS-XARM_ETM_PIT_GAIN 1 -5.000000000000000e-02
=> C1:ASS-XARM_ETM_PIT_GAIN 1 -1.500000000000000e-02 |
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Tue Dec 8 11:24:45 2015, yutaro, Summary, Computer Scripts / Programs, Scripts for loss map measurement
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Here I explain usage of my scripts for loss map measurement. There are 7 script files in a same directory /opt/rtcds/caltech/c1/scripts/lossmap_scripts. With
these scripts, round trip loss of an arm cavity with the beam spot on one mirror shifted to 5x5 (option: 3x3) points is measured. You can choose on
which cavity you measure, the beam spot on which mirror you shift, and maximum shift of the beam spot in vertical and horizontal direction. |
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Tue Dec 8 15:57:16 2015, yutaro, Summary, LSC, Power recycling gain estimation from arm loss measurement
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I estimated power recycling gain with the results of arm loss measurement.
From elog 11818 and 11857,
round trip losses including transmittivity of ETM of Y arm and X arm (let us call them |
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Thu Dec 10 12:33:04 2015, yutaro, Update, LSC, strange behavior of ASDC
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I did additional tests for the strange behavior of ASCD. ETMY, ETMX and ITMY were misaligned so that only light reflected by ITMX went into AS port.
I had done similar measurement before with ITMY YAW varied.
Attachment 1 shows how ASDC level changed when ITMX PIT varied. |
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Thu Dec 10 19:53:22 2015, yutaro, Update, LSC, strange behavior of ASDC
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To check if the strange behavior of ASDC is caused by SR2/SR3 or not, I did the following measurement:
ASDC measures the power of the light reflected by ITMX. POXDC measures the power of the light reflected by ITMX and SRM successively. Then I
varied the angle of ITMX in YAW direction and compared the behaviors of ASDC and POXDC. |
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Fri Dec 11 09:35:44 2015, yutaro, Update, LSC, Power recycling gain estimation from arm loss measurement
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I took PR3 AR reflectivity and calculated PRG (PR3 is flipped and so AR surface is inside PRC).
As shown in attached figure, which shows AR specification of the LaserOptik mirror (PR3 is this mirror), AR reflectivity of PR3 is ~0.5 %.
Since resonant light in PRC goes through AR surface of PR3 4 times per round trip, round trip loss due to this is ~2 %. Then I got |
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Fri Dec 11 15:37:50 2015, yutaro, Update, LSC, Power recycling gain estimation from arm loss measurement
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Attached is the plot of relation between the average arm round trip loss and power recycling gain. 2 % loss due to PR3 AR reflection is taken
into account. |
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Fri Dec 11 16:16:36 2015, yutaro, Update, Optical Levers, Calibration of oplevs for ITMX/ETMX
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Based on calibration measurement I have done (elog 11785, 11831), I
updated calibration factors of oplevs on medm screen as follows. Not to change loop gain oplev servo, I also changed oplev servo gain.
C1:SUS-ETMX_OL_PIT_CALIB, C1:SUS-ETMX_OL_PIT_GAIN |
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Mon Oct 25 20:20:59 2010, yuta, Joe, Update, CDS, DAQ channel number etc
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[U][B]Summary:[/B][/U]
We split the old SDSEN filters to SDSEN, SDSIDE, SDCOIL last week.
Along with this change, the TP channel number changed unfortunately.
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Wed Sep 29 16:56:36 2010, yuta, Update, VAC, 2 doors opened
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(Steve, Koji, Joe, Kiwamu, Yuta)
Background:
The vent was started on Monday, and finished on Tuesday. |
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Wed Sep 29 18:28:32 2010, yuta, Update, Computers, aldabella connects to the wireless network
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Background:
We need laptops that connect to the wireless network to use them in the lab.
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Thu Sep 30 14:09:33 2010, yuta, Update, Computers, mariabella connects to the wireless network
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Background:
We need laptops that connect to the wireless network to use them in the lab.
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Thu Sep 30 18:51:50 2010, yuta, Update, Computers, setting up aldabella and mariabella
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(Kiwamu, Yuta)
Background: |