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ID Date Author Type Categoryup Subject
  4836   Mon Jun 20 09:04:13 2011 steveUpdateSUSETMX damping restored

ETMX sus damping restored

  4839   Mon Jun 20 11:04:03 2011 NicoleUpdateSUSWork Plan for Week 2

Here is my work plan for this week:

Current Week Plan (Week 2) (As of 6/17/11)


Setting Up for Horizontal Displacement Measurements

1) Help Steve clean small table for experiment

2) Remove aluminum base from TT suspension

3) Mount shaker onto table base

4) Mount horizontal slider onto table base

5) Connect TT suspension, shaker, and horizontal slider

Begin Assembly of Sensors

1) Begin building circuit for displacement photosensors

2) Calibrate photosensor using linear regions of power versus distance curves

3) Circuit box for photosensors?

  4844   Mon Jun 20 18:12:20 2011 NicoleUpdateSUSSmall Table Cleaned and Levelled


The small optical bench (next to the MC-2 Chamber and the tool box tower) has been cleared of the misc. object previously on it, cleaned, and leveled (after much calibration X___X).

PLEASE, PLEASE, PLEASE do NOT MOVE OR HIT THE TABLE! It was incredibly painful to level.

This is how leveling the table made me feel...


VERY SAD...so do not move please!

The shaker has already been moved to the table and the amplifier for my shaking experiment is located behind the table (not on the table, as to prevent scratching).



  4853   Wed Jun 22 12:24:44 2011 NicoleSummarySUSMidweek 2 Work Summary

I have made my transfer function model and posted it to the suspension wiki. Here is the link to my model!

Bode Plot Model

Please let me know if there need to be any adjustments, but I have posted the bode plots, a model image, and an explanation of why I think it's right! ^ ___^ V

I am currently working on the photo sensor circuit for the displacement detector. So far, I have gotten the infared LED to light up! ^ ___^ V

I am now trying to get a plot of forward voltage versus current for the LED. HOPEFULLY it will match the curve provided in the LED datasheet.

I'm using the bread board circuit box and when I'm not working at the bench, I have signs posted. PLEASE DO NOT REMOVE THE CONNECTIONS! It is

fine to move the bread board circuit box, but please do not disturb the connections > ____<

Here is a photo of the workspace


  4858   Wed Jun 22 18:41:23 2011 NicoleSummarySUSBROKEN bread board circuit box and L9337 LED Current Versus Voltage Curve

NOTE: The potentiometers on the bread board circuit box (the one I have been using with the signal generator, DC power, LED displays, and pulse switches) is BROKEN!

The potential across terminals 1 and 2 (also 2&3) fluctuates wildly and there dial does not affect the potential for the second potentiometer (the one with terminals 4, 5, and 6).

This has been confirmed by Koji and Jaimie.  PS I didn't break it! >____<


NEVERTHELESS, using individual resistors and the 500 ohm trim resistor, I have managed to get the current versus forward voltage plot for the Hamamatsu L9337 Infared LED


  4868   Thu Jun 23 21:35:46 2011 Jamie, Rana, KiwamuUpdateSUSFix calibration for sus sensors

We have fixed the counts-to-micron (cts2um) calibration for the suspension sensor filters. Each suspension sensor filter bank (e.g. ULSEN) has a "cts2um" calibration filter. These have now been set with the following flat gains:

   40 V       10^3 um         um
 -------- *  --------  = .36  --
 2^16 cts     1.7 V           ct

The INMTRX was also fixed with proper element values:

.25 .25 .25 .25 0 POS
1.666 1.666 -1.666


1.666 -1.666 -1.666 1.666 0 YAW
0 0 0 0 1 SIDE

This was done for all core optic suspensions (BS, PRM, SRM, ITMX, ITMY, ETMX, ETMY).


  4869   Thu Jun 23 22:00:22 2011 JamieUpdateSUSburt snapshot

I recorded a burt snapshot of these settings: /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2011/Jun/23/21:40

  4875   Fri Jun 24 01:05:32 2011 NicoleSummarySUSTransfer Function Model Analysis Summary and New Posted LED V vs. I Curve

I have updated the TT suspension wiki to include a new page on my transfer function model. In this new page, an introduction and analysis of my transfer function (including a comparison of the transfer functions for a flexibly- and rigidly-supported damper) are included.  This page contains linear and logarithmic bode plots.  Here is a link to the transfer function page.


I have also updated my photosensor page on the TT suspension wiki so that the experimental data points in my current versus voltage plot are plotted against the curve provided by the Hamamtsu data sheet. I have also included an introduction and analysis for my mini-experiment with the forward voltage and forward current of the LED. Here is link to the photsosensor page.

  4876   Fri Jun 24 07:40:23 2011 steveUpdateSUSPRM damping restored

The PRM sus damping restored. C1:SUS-PRM_SDPD_VAR is still 20-30mV and going up.  Side gain  turned on. This pulled it down to 5-8 mV

Why is the side osem sensing voltage 4.4V ? It can not be higher than ~2.4V.......something is rotten in the state of Denmark?

Edit by KI:

 It's because Valera increased the transimpedance gain of the PRM SIDE OSEM to match the signal level to the new ADC range (#3913 ).

  4879   Fri Jun 24 17:04:25 2011 NicoleUpdateSUSBasic Laser Safety Training; Moved TT Mirror; Horizontal Displacement Mech Plan

Today Ishwita, Sonali, and I completed basic laser safety training with Peter King. I completed the Laser Safety Quiz and have turned in my certificate sheet.

I just need to turn in a signed copy of the Lab Safety Checklist to SFP (which I can now have signed by Koji after completing the course).


Steve and I have removed the TT mirror from the clean box. It is now on the small optical table in the lab that I have been working on.  Thanks to Steve, all of the mechanical components for the horizontal displacement measurement experiment are compiled and on the small optical table. Here is a photo of the small optical table with the gathered components. CompiledParts.JPG

The plan is to attach the slider and the shaker directly to the black mounting plate. On the slider, we we then place the smaller black mounting plate (with the lip). The lip will attach to the shaker. We know exactly where to drill and everything is lined up. The shaker will be placed on the smaller black mounting plate (with the lip).  The assembly will begin on Monday.


Here is a photo of the planned set-up for the shaker and the horizontal slider + mounting base.


  4887   Sun Jun 26 18:35:16 2011 ranaHowToSUSfree swing all optics

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.

Attachment 1: ringdown.png
  4892   Tue Jun 28 01:18:53 2011 ranaHowToSUSfree swing all optics

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.

  4902   Tue Jun 28 21:05:05 2011 JamieUpdateSUSSUS control model updated

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:


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.

  4904   Tue Jun 28 22:36:04 2011 JamieUpdateSUSChecking binary switching of SUS whitening filter

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


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

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

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

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

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

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

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
Attachment 1: botest.py
#!/usr/bin/env python

import sys
import os
import subprocess
import time
import pickle
from numpy import *
import nds
import matplotlib
... 207 more lines ...
  4906   Wed Jun 29 01:23:21 2011 haixingUpdateSUSissues in the current quad maglev system

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.

  4907   Wed Jun 29 11:13:13 2011 JenneUpdateSUSissues in the current quad maglev system


(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.

 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. 

  4908   Wed Jun 29 11:25:07 2011 NicoleSummarySUSWeekly Summary of Work

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.


  4913   Wed Jun 29 22:35:06 2011 NicoleSummarySUSCompleted Quad photodiode Box Circuit Diagrams

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.



  4916   Thu Jun 30 01:50:02 2011 JenneUpdateSUSITMX whitening, ETMX left free swinging

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!

  4921   Thu Jun 30 11:36:54 2011 JamieUpdateSUSRe: ITMX whitening, ETMX left free swinging


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.

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.


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!

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.

  4929   Fri Jul 1 16:01:48 2011 JamieUpdateSUSETM binary whitening switching fixed

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.


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

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.


  • 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.

  4930   Fri Jul 1 18:41:53 2011 JamieUpdateSUSCore optic sus damping controllers normalized

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.


  4931   Fri Jul 1 18:48:13 2011 JamieUpdateSUSETMY sus controller found to be in a bad state

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.

  4932   Fri Jul 1 18:54:34 2011 JamieUpdateSUSETMY binary whitening switching confirmed to be fixed

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:

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

  4933   Fri Jul 1 20:22:24 2011 ranaUpdateSUSETMY sus controller found to be in a bad state

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.

  4934   Fri Jul 1 20:26:29 2011 ranaSummarySUSAll SUS Peaks have been fit

         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.

Attachment 1: Screen_shot_2011-07-01_at_8.17.22_PM.png
  4938   Tue Jul 5 13:35:56 2011 steveUpdateSUSPRM damping restored

The PRM sus damping was restored. It's side rms motion came down from 35 to 4 mV immediately.      Lab   air quality is back to normal.


  4941   Tue Jul 5 18:57:10 2011 JamieUpdateSUSMore normalization of all sus controllers

Based on Rana's comment I have gone through and moved all of the corner frequencies for the high pass filters in the SUS damping controllers to 30 Hz.  I did this for all optics (MC1, MC1, MC3, BS, ITMX, ITMY, PRM, SRM, ETMX, ETMY) all degrees of freedom (POS, PIT, YAW, SIDE).

Rana also suggested I turn off all of the BounceRoll filters until we get a chance to tune those individually for all the suspensions.

Finally, I normalized the MC SUSXXX filter banks to look just like all the other suspensions.

All damping filter banks for all degrees of freedom for all single suspensions should all be the same now (modulo the differences in the BounceRoll filters, which are now turned off).

  4942   Tue Jul 5 21:26:51 2011 ranaUpdateSUSMore normalization of all sus controllers

This is getting closer, but with the whitening left OFF and the cts2um filter also OFF, none of the suspensions are working correctly. I'm shutting down all the watchdogs until someone gets around to setting the damping gains and filters correctly.

I'm attaching a screenshot of some of the problems I see so far with MC3.

I'm going to try to get the MC suspensions working OK for tonight so that we can use them for the PRMI locking work.

Update #1: None of the MC SUS DAQ channels are found by dataviewer....SUS debugging speed reduced by 10x.  Tue Jul 05 21:38:17 2011

Update #2: POS/PIT/YAW BIAS sliders now seem to work, but are ~1000x too weak to do anything.   Tue Jul 05 21:41:38 2011


Attachment 1: Screenshot-1.png
  4943   Wed Jul 6 02:12:36 2011 kiwamuUpdateSUSRe : More normalization of all sus controllers

[Jenne / Rana/ Kiwamu]

 We found the 30 Hz high pass filters had lower gain than what they used to be at low frequcnies.

So we increased the gain of the high pass filters called '30:0.0'  by a factor of 10 to have the same gain as before.

Now all the suspension shows some kind of damping. Needs more optimizations, for example Q-adjustments for all the suspensions...

Quote from #4942

This is getting closer, but with the whitening left OFF and the cts2um filter also OFF, none of the suspensions are working correctly.


  4944   Wed Jul 6 10:35:35 2011 JamieUpdateSUSRe : More normalization of all sus controllers


We found the 30 Hz high pass filters had lower gain than what they used to be at low frequcnies.

So we increased the gain of the high pass filters called '30:0.0'  by a factor of 10 to have the same gain as before.


I'm not convinced that this is what you want to do, or at least I wouldn't do it this way.  The "k" in the zpk filter was set such that the filter had unity gain above the high-pass cut-off frequency.  For a 30 Hz high-pass the k needs to be a factor of 10 smaller than it would be for a 3 Hz high-pass to achieve this high frequency unity gain.

As it is now these HP filters have 20 dB of gain above 30 Hz.  If the open loop transfer function needs to more gain I would have done that by adjusting the overall DC gain of the filter bank, not by increasing the gain in this one filter.  Maybe you guys have been doing it differently, though.  Or maybe I'm just completely off base.

  4945   Wed Jul 6 11:45:20 2011 JamieUpdateSUSMore normalization of all sus controllers


I'm attaching a screenshot of some of the problems I see so far with MC3.

I tried to fix all of the problems that I could identify in this screen shot:

  • Fixed the TO_COIL output filter matrix screen to correctly point to the matrix element filter screens (all SUS)
  • Removed MCL sections from SUS_XXX_POSITION screens, except for MC2.  I also modified the _POSITION screens for the ETMs to refer to ALS instead of MCL.
  • Zeroed out all of the lockin gains in the TO_COIL matrices (MC SUS)
  • Made sure all whitening filter were ON (all SUS)
  • Made sure all cts2um calibration filters were on (all SUS)
  • Made sure all oplev servos were on (all SUS)
  4946   Wed Jul 6 15:32:32 2011 JamieUpdateSUSRe : More normalization of all sus controllers

So after talking to Kiwamu about it, I understand now that since the damping loops need all of this extra gain when the high-pass corner is moved up, it's more convenient to put that gain in the control filter itself, rather than having to crank the overall DC gain up to some inconveniently high value.

  4947   Wed Jul 6 16:44:37 2011 steve, kiwamuUpdateSUSBS oplev spectra

Healthy BS oplev

Attachment 1: BS.jpg
  4948   Wed Jul 6 18:15:26 2011 kiwamuUpdateSUSRe: BS oplev spectra

[Steve / Kiwamu]


 Since the oplevs were the ones we haven't carefully tested, so the oplevs need to be checked.

This checking is also a part of the suspension optimizations (see the minutes of the last 40m meeting).

 In this work Steve will check two things for all the oplevs :

    1. Noise level including the dark noise, electrical noise and ADC noise to just make sure that the noise are blow the signal levels below ~ 30Hz.

    2. The spectra of the signals to make sure there are no funny oscillations and unexpected structures


Measurement :

  To check the things listed above, we take two kinds of oplves' spectra :

     1. "dark noise" when the He-Ne beam is blocked.

     2. "signals" when the optics are damped by only OSEMs

 We did these checks on the BS oplev today (see the last entry).

All of them are fine, for example the dark noise (including electrical noise and ADC noise) are below the signal levels.

And no oscillation peak was found. Steve will go through all of the oplevs in this way.

Quote from #4947

Healthy BS oplev

  4956   Fri Jul 8 09:53:49 2011 Nicole SummarySUSSummer Progress Report 1

A copy of my summer progress report 1 has been uploaded to ligodcc 7/711 and I have just added a copy to the TTsuspension wiki


PDF copy of Summer Progress Report

  4963   Tue Jul 12 17:30:24 2011 steve,UpdateSUSBS oplev spectra


Healthy BS oplev

 I repeated the BS oplev spectrum today and I do not understand why it does look different. I did it as Kiwamu describes it in entry#4948  The oplev servo was left ON!

Attachment 1: BS_oplev.jpg
  4964   Wed Jul 13 12:24:46 2011 NicoleUpdateSUSWeekly Update
This week, I have been working on the photosensor circuit box.  This photosensor box will contain the current-stabilizing power supply and
voltage readout for the two photosensors I plan to build.
Suresh helped to walk me through the design of the photosensor circuit (image below) so I now understand how the circuit works.
Jaimie helped me to reorganize the original circuit layout I had to make it easier to follow. I have now redone half of the circuit (enough for one LED and photodiode pair). I still need to put in the voltage-regulators to provide the + and - 15 V neeCto power the op-amps but I will do that after testing the circuit.

In order to test this preliminary circuit, I need to build the photosensor heads.  Yesterday, Suresh helped me to open one of the professionally-build photosensors in the lab to understand how to arrange my photosensor heads. I now understand that I need to rigidly-mount the PCB to photosensor head box. I plan to use the PCB below. It will be sufficient for the lower-frequency range (below 10Hz) that I am interested in. 


 I would like to use a metal box like the one below to make each photosensor head. I looked in the lab last night for similar boxes but could not find one. Does anyone know where I can find a similar metal box?



I am now working on accelerometer. I am working on attaching these metal wires to the pins of the accelerometer so that I can use clip leads to power and extract voltage measurements from my circuit.


  4966   Thu Jul 14 09:38:50 2011 steve,UpdateSUSBS oplev spectra



Healthy BS oplev

 I repeated the BS oplev spectrum today and I do not understand why it does look different. I did it as Kiwamu describes it in entry#4948  The oplev servo was left ON!

 It is working today! Finally I repeated the BS spectra, that we did with Kiwamu last week

Attachment 1: BS_oplev.jpg
  4967   Thu Jul 14 15:27:08 2011 steve,UpdateSUSSUS oplev spectras




Healthy BS oplev

 I repeated the BS oplev spectrum today and I do not understand why it does look different. I did it as Kiwamu describes it in entry#4948  The oplev servo was left ON!

 It is working today! Finally I repeated the BS spectra, that we did with Kiwamu last week

 The optical levers were centered during these measurements  without the reference of locked cavities.  They have no reference value now.

SRM sus need some help. ITMX is showing pitch/yaw modes of the pendulum .....OSEM damping is weak?

Attachment 1: BS_oplev.jpg
Attachment 2: PRM_oplev.jpg
Attachment 3: ITMX_oplev.jpg
Attachment 4: ETMX_oplev.jpg
Attachment 5: ETMY_oplev.jpg
Attachment 6: SRM_oplev.jpg
Attachment 7: ITMY_oplev_b.jpg
  4969   Thu Jul 14 20:24:32 2011 NicoleSummarySUSPhotosensor Head Lessons

Today I tested the photosensor head combination (2 Hamamatsu S5971 photodiodes and 1 Hamamatsu L9337 LED). I discovered that I had burnt out the LED and the photodiodes when I soldered them to the PCB board.

After looking up soldering information on Hamamatsu photodiodes, I learned that I need to solder at least 2 mm away from the head. I checked the pins of my burnt-out photodiodes and I had soldered 1.5 mm away from the head. To prevent this problem from happening again, Suresh suggested that I clip a lead onto photodiode/LED pin while I solder on connections to help dissipate some of the heat.

Today I was able to get a single photodiode (not attached to the PCB) to measure light emitted from an LED and I observed how voltage fluctuated as I moved the photodiode around the LED.

Suresh and Jamie also helped me to fix my photosensor head design (to make it more electrically-stable). Originally, I had planned to solder the LED and photodiodes onto a PCB and to mount that PCB to the front of a small metal Pomona Electronics box (with a whole cut out for the photodiodes and LED) using spacers, screws, and nuts.  However, the PCB I am using to solder on the LED and photodiodes has metal connections that may cause problems for the LED and photodiodes lying on the surface. Now, the plan is to have the LED and photodiodes mounted to the PCB with an insulatory PCB in between. Below is an explanatory picture.  I will determine the placement of the LED and photodiodes after making screws holes in the two PCBs to attach to the metal face of the box. I want to attach the screw holes first to make sure that the PCBs (and attached photosensor) are centered.



  4970   Fri Jul 15 01:11:21 2011 KojiSummarySUSPhotosensor Head Lessons

Rotate the PDs and the LED so that you can put them as close as possible.
This is to increase the sensitivity of the sensor. Think why the closer the better.

  4971   Fri Jul 15 08:48:36 2011 JamieSummarySUSPhotosensor Head Lessons

Nicole: I thought we had decided to use teflon as the insulator between the PCB (yellow) and the LED/PDs?  I don't think you should use another circuit board with copper on it.  The copper will short the LED/PD heads to the metal box, which might be problematic.

Otherwise the design looks pretty good.  I think the PDs have three leads each, yes?

  4972   Fri Jul 15 09:25:02 2011 ranaUpdateSUSSUS oplev spectras

In addition to the OL quadrants, you need to plot the OPLEV_PERROR and OPLEV_YERROR signals since these are the real signals we use for finding the mirror motion. If they're not in the Dataviewer, Jamie should add them as 256 Hz DAQ channels (using these names so that we have the continuity with the past). These DAQ channels correspond to the IN1 channels for the OL filter banks.

Also JPG are banned from the elog - you should put all of the plots into a single, multipage PDF file in honor of the new Wagonga.

  4974   Fri Jul 15 14:23:30 2011 NicoleSummarySUSPhotosensor Head Lessons


 Ah! I see! Thank you!

I should put the LEDs and photodiodes closer together so that more of the reflected light falls on the photodiodes and the photodiodes have a higher response.

Also the reflectivity of the mirror will be optimized if the incident light is normal to the mirror surface. We will be setting up the photosensor and mirror so that the LEDs

emit light normal to the mirror surfaceDuring displacement, this light may be slightly off-normal but still close to normal incidence. We want the photodiodes to be close to the LED since we want

them to detect light that is close to the path of normal incidence (small angles of reflection). [Thanks to Jenne for helping me figure this one out!]


Thank you for the suggestion ^___^

  4975   Fri Jul 15 14:29:30 2011 NicoleSummarySUSPhotosensor Head Lessons


 You are right Jamie! Thank you for the correction! I will now use the Teflon sheet instead of the PCB piece.

The photodiodes do have three legs, but I imagined the third one lying on a different plane, since it is spaced apart from the two I have drawn.

I should include this third leg in my drawing?

  4976   Fri Jul 15 16:14:00 2011 steveUpdateSUSBS oplev error signal spectra
Attachment 1: BS_opl_ersig.pdf
  4983   Mon Jul 18 15:51:04 2011 steveUpdateSUSETMY spectra of oplev error signal
Attachment 1: ETMYopler.png
  4987   Tue Jul 19 09:19:14 2011 steveUpdateSUSPRM damping restored

The PRM watchdogs were tripped. The side was kicked up to 180mV Damping was restored.

  5000   Wed Jul 20 12:05:08 2011 NicoleSummarySUSWeekly Summary

Since last week Wednesday, I have since found a Pomona Electronics box (thanks to Jenne)

to use for my photosensor head circuit (to house the LED and 2 photodiodes). Suresh has

shown me how to use the 9-pin Dsub connector punch, and I have punched a hole in this box

to attach the Dsub connector. 


Since this past entry regarding my mechanical design for the photosensor head (Photosensor Head Lessons),

I have modified the design to use a Teflon sheet instead of a copper PCB and I have moved the LED

and photodiodes closer together, upon the suggestions of Jamie and Koji.  The distance between

components is now 0.112" instead of the initial 0.28".  Last night, I cut the PCB board for the LED

and photodiodes and I drilled holes onto the PCB board and Teflon sheet so that the two may be

mounted to the metal plate face of the Pomona box.  I still need to cut the viewer hole for and

drill screws into the face plate.


I have also been attempting to debug my photosensor circuit (box and LED/photodiode combination).

Since this last entry (Painful Votlage Regulator and Circuit Lessons), Suresh has helped me to get the parts

that I need from the Downs Electronics lab (15 wire ribbon cable, two 9 pin D-sub connectors M,

one 15 pin D-sub connector M, one 16 pin IDC connector). Upon the suggestion of Jamie, I have

also made additional safety changes to the circuit by fixing some of the soldering connections

so that all connections are done with wires (I had a few immediate lines connected with solder).

I believe the the photosensor circuit box is finally ready for testing. I may just need some help

attaching the IDC connector to the ribbon cable. After this, I would like to resume SAFELY

testing my circuit.


I have also been exploring SimMechanics. Unfortunately, I haven't been able to run the

inverted pendulum model by Sekiguchi Takanori. Everytime I attempt to run it, it says

there is an error and it shuts down Matlab. In the meanwhile, I have been watching

SimMechanics demos and trying to understand how to build a model. I'm thinking that

maybe once I figure out how SimMechanics works, I can use the image of his model

(I can see the model but it will not run) to construct a similar one that will hopefully work.


I have also been attempting to figure out the circuitry for the pre-assembled

accelerometer (made with the LIS3106AL chip).  I have been trying to use a multi-meter

to figure out what the components are (beyond the accelerometer chip, which I have

printed out the datasheet for), but have been unsuccessful at that. I have figured out

that the small 5 pin chip says LAMR and is a voltage regulator. I am hoping that if I can

find the data sheet for this voltage regulator, I can figure out the circuitry. Unfortunately,

I cannot find any datasheets for a LAMR voltage regulator. There is one by LAMAR, but

the ones I have seen are all much larger. Does anyone know what the miniature voltage

regulator below is called and if "LAMR" is short for "LAMAR"?




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