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ID Date Author Type Category Subject
  2856   Wed Apr 28 14:15:58 2010 AlbertoUpdateIOOMC alignment


 That's interesting.

Would it be possible to write about the technique on a wiki page as you get measurements and results?

  2855   Wed Apr 28 12:05:44 2010 ZachUpdateIOOMC alignment

I have worked out the first set of adjustments to make on the MC mirrors (all angle figures are in units of the increments on the control screen)

Using the method described in the previous post, I obtained the following matrix relating the angle-to-length coupling and the angular deviations. In the following matrix, Mij corresponds to the contribution of the jth degree of freedom to the ith A-to-L coupling, with the state vector defined as xi = (MC1P, MC2P, MC3P, MC1Y, MC2Y, MC3Y), where each element is understood as the angular deviation of the specific mirror in the specific direction from the ideal position, such that x = 0 when the cavity eigenmode is the correct one and the beams are centered on the mirrors (thus giving no A-to-L coupling regardless of the components of M).


M =

   1.0e+03 *

   -0.2843   -0.4279   -0.1254         0         0         0

   -0.8903   -0.4820   -0.6623         0         0         0

    0.5024    0.0484   -0.0099         0         0         0

         0         0         0         0.1145   -0.1941   -0.3407

         0         0         0         0.0265    1.5601    0.2115

         0         0         0         0.1015    0.1805   -0.0103,

giving an inverse

M-1 =  

    0.0003   -0.0001    0.0020         0         0         0

   -0.0031    0.0006   -0.0007         0         0         0

    0.0018   -0.0018   -0.0022         0         0         0

         0         0         0        -0.0013   -0.0015    0.0117

         0         0         0         0.0005    0.0008   -0.0008

         0         0         0        -0.0037   -0.0010    0.0044

The initial coupling vector is then acted on with this inverse matrix to give an approximate state vector x containing the angular misalignments of each mirror in pitch and yaw. The results are below:


   1P:  0.0223

   2P: -0.0733

   3P:  0.3010

  1Y:  -0.1372

  2Y:   0.0194

  3Y:  -0.0681


  2854   Wed Apr 28 09:21:16 2010 ZachUpdateelogelog restarted

And again.


 Restarted the elog with the script as it was down.


  2853   Wed Apr 28 08:55:19 2010 ZachUpdateelogelog restarted

 Restarted the elog with the script as it was down.

  2852   Tue Apr 27 22:28:58 2010 ZachUpdateIOOMC alignment

Beginning last week, I have been helping Koji with some of the IO work that must be done for the 40m upgrade. The first thing he asked me to do is to help with the alignment of the MC.

As I understand, it became apparent that the IFO beam was not centered on all (or any) of the MC mirrors, which is disadvantageous for obvious reasons. We are trying to correct this, using the following strategy:

  1. Adjust the MC mirrors into rough alignment, isolate a strong TEM00, and lock the cavity
  2. Fine-tune the alignment by minimizing the REFL power when locked (in these first two steps, we adjusted only MC2 & MC3, assuming that the REFL beam was centered on the PD, and wanting to keep it that way). At this point, the cavity is resonating some asymmetric mode, looking something like (not to scale---for illustration only):MC_misaligned.png
  3. Shake all three mirrors (in succession) in pitch and yaw, each time demodulating the error signal at the frequency used for the excitation and recording the magnitude and phase of the response.
  4. Move one mirror's DC orientation, repeat step 3, and then restore the mirror to its original position
  5. Repeat step 4 for both angular degrees of freedom of each mirror

Using the results of these measurements, it is possible to evaluate the components of a block-diagonal matrix M which relates the tilt-to-displacement coupling of each DOF to each mirror's misalignment in that degree, i.e.,

a = M x

with a a 6-dimensional vector containing the coupling of each degree of freedom to the length of the cavity and x a 6-dimensional vector containing the angular misalignments of each. Due to orthogonality of pitch and yaw, M will take the form of a 6x6 matrix with two non-zero 3x3 blocks along the diagonal and zero matrices on the off-diagonal blocks.

The idea is to isolate components of M by moving one mirror at a time, solve for them, then find the inverse M-1 that should give us the required angular adjustments to obtain the beam-centered ideal cavity mode.

In theory, this need only be done once; in practice, our measurement error will compound and M will not be accurate enough to get the beams exactly centered, so we will have to iterate.

NOTE: The fact that we are adjusting the three cavity mirrors to obtain the ideal mode means that we will necessarily tarnish our coupling into the cavity. Once we have adjusted the mirrors once, we will need to re-steer the input beam and center it on the REFL diode. 

Status: This process has been completed once through step 5. I am in the process of trying to construct the matrix for the first adjustment.


  2851   Tue Apr 27 15:29:16 2010 KevinUpdatePSLre: 2W Vertical Beam Profile

I thought that the micrometer I was using to move the razor through the laser beam was metric; however, it is actually english.

After discovering this mistake, I converted my previous measurements to centimeters and fit the data to

w = sqrt(w0^2+lambda^2*(z-z0)^2/(pi*w0)^2) with the following results:

reduced chi squared = 14.94

z0 = (-4.2 ± 1.9) cm

w0 = (0.013 ± 0.001) cm

Attachment 1: vbp.jpg
Attachment 2: vbp_residuals.jpg
  2850   Tue Apr 27 14:18:53 2010 kiwamuUpdateGreen Lockingwaist positon of Gaussian beam in PPKTP crystals

The mode profile of Gaussian beams in our PPKTP crystals was calculated.

I confirmed that the Rayleigh range of the incoming beam (1064 nm) and that of the outgoing beam (532 nm) is the same.

And it turned out that the waist postion for the incoming beam and the outgoing beam should be different by 13.4 mm toward the direction of propagation.

These facts will help us making optical layouts precisely for our green locking.


The result is shown in the attached figure, which is essentially the same as the previous one (see the entry).

The horizontal axis is the length of the propagation direction, the vertical axis is the waist size of Gaussian beams.

Here I put x=0 as the entering surface of the crystal, and x=30 mm as the other surface.

The red and green solid curve represent the incoming beam and the outgoing beam respectively. They are supposed to  propagate in free space.

And the dashed curve represents the beams inside the crystal.

A trick in this calculation is that: we can assume that  the waist size of 532 nm is equal to that of 1064 nm divided by sqrt(2) . 

If you want to know about this treatment in detail,  you can find some descriptions in this paper;

"Third-harmonic generation by use of focused Gaussian beams in an optical super lattice" J.Opt.Soc.Am.B 20,360 (2003)"

Attachment 1: mode_in_PPKTP.png
  2849   Tue Apr 27 11:16:13 2010 josephbConfigurationCDSWiki page with CDS .mdl names, shared memory allocation

I've added a new page in the wiki which describes the current naming scheme for the .mdl model files used for the real time code generator.  Note, that these model names do not necessarily have to be the names of the channels contained within.  Its still possible to make all suspension related channels start with C1:SUS- for example.  I'm also allocating 1024 8 byte channels for shared memory address space for each controller and each simulated plant.

The wiki page is here

Name suggestions, other front end models that are needed long term (HEPI is listed for example, even though we don't have it here, since in the long run we'd like to port the simulated plant work to the sites) are all welcome.

  2848   Mon Apr 26 21:12:53 2010 KojiUpdateSUSPRM/SRM standoffs glued

Kiwamu and Koji

The PRM/SRM were balanced with the standoffs. We glued them to the mirror.

This was the last gluing so far until we get new PRM/ETMs.

  2847   Mon Apr 26 17:34:31 2010 KojiUpdatePSLre: 2W Vertical Beam Profile

Give me the plot of the fit, otherwise I am not convinced.


I tried Koji's suggestions for improving the fit to the vertical beam profile; however, I could not improve the uncertainties in the fit parameters.

  2846   Mon Apr 26 16:51:37 2010 KevinUpdatePSLre: 2W Vertical Beam Profile

I tried Koji's suggestions for improving the fit to the vertical beam profile; however, I could not improve the uncertainties in the fit parameters.

I started retaking the data today with the same laser settings used last time and noticed that the photodiode was saturating. We were using an ND 4.0 neutral density filter on the photodiode. Koji and I noticed that the coating on the filter was reduced in the center and added an additional ND 0.6 filter to the photodiode. This seemed to fix the photodiode saturation.

I think that the photodiode was also saturating to a lesser extent when I took the last set of data. I will take another vertical beam profile tomorrow.

[Edit by KA: Metallic coating started being evaporated and the ND filters reduced their attenuation. We decided to use absorptive one as the first incident filter, and put a thinner one behind. This looked fine.]

  2845   Mon Apr 26 12:24:58 2010 josephbUpdateGeneralDaily Downs update

Talked with Jay briefly this morning.

We are due another 1-U 4 core (8 CPU) machine, which is one of the ones currently in the test stand.  I'm hoping sometime this week I can convince Alex to help me remove it from said test stand.

The megatron machine we have is definitely going to be used in the 40m upgrade (to answer a question of Rana's from last Wednesday's meeting).  Thats apparently the only machine of that class we get, so moving it to the vertex for use as the LSC or SUS vertex machine may make sense.  Overall we'll have the ASS, OMC, Megatron (SUS?), along with the new 4 1-U machines, for LSC, IO, End Y and End X.  We are getting 4 more IO chassis, for a total 5.  ASS and OMC machine will be going without full new chassis.

Speaking of IO chassis, they are still being worked on.  Still need a few cards put in and some wiring work done.  I also didn't see any other adapter boards finished either.

  2844   Mon Apr 26 11:29:37 2010 josephbUpdateComputersUpdated bitwise.pm in RCG SVN plus other fixes

To fix a problem one of the models was having, I checked the CVS version of the Bitwise.pm file into the SVN (located in /home/controls/cds/advLigoRTS/src/epics/util/lib), which adds left and right bit shifting funtionality.  The yec model now builds with the SVN checkout.

Also while trying to get things to work, I discovered the cdsRfmIO piece (used to read and write to the RFM card) now only accepts 8 bit offsets.  This means we're going to have to change virtually all of the RFM memory locations for the various channels, rather than using the values from its previous incarnation, since most were 4 bit numbers.  It also means it going to eat up roughly twice as much space, as far as I can tell.

Turns out the problem we were having getting to compile was nicely answered by Koji's elog post.  The shmem_daq value was not set to be equal to 1.  This caused it to look for myrimnet header files which did not exist, and caused compile time errors.  The model now compiles on megatron.

[Edit by KA: 4 bit and 8 bit would mean "bytes". I don't recall which e-log of mine Joe is referring.]


  2843   Mon Apr 26 11:14:04 2010 KojiUpdateGreen LockingTemperature scan for PPKTP

I scanned the temperature of the crystal oven on Friday night in order that we can find the optimal temperature of the crystal for SHG.

The optimal temperature for this crystal was found to be 36.2 deg.

The crystal is on the PSL table. The incident beam on the crystal is 27.0mW with the Newport power-meter configured for 1064nm.
The outgoing beam had 26.5mW.

The outgoing beam was filtered by Y1-45S to eliminate 1064nm. According to Mott's measurements, Y1-45S has 0.5% transmission for 1064nm, while 90% transmission for 532nm. This means I still had ~100uW after the Y1-45S. This is somewhat consistent with the offset seen in the power-meter reading.

First, I scanned the temperature from 28deg to 40deg with 1deg interval.The temperature was scaned by changing the set point on the temperature controller TC-200.The measurements were done with the temperature were running. So, the crystal may have been thermally non-equilibrium.

Later, I cut the heater output so that the temperature could be falling down slowly for the finer scan. The measurement was done from 38deg to 34deg with interval of 0.1deg with the temperature running.

I clearly see the brightness of the green increase at around 36 deg. The data also shows the peak centered at 36.2deg. We also find two lobes at 30deg and 42deg. I am not sure how significant they are.

Attachment 1: SHG_pow.png
  2842   Mon Apr 26 11:13:28 2010 steveOmnistructurePEMAC on/off is working


Koji and I wanted to turn off the IFO-room AC so the wind would not blow on MC1-3. We could not. The switches were probably bypassed when the power transformer was replaced at the last scheduled power outage.

 There is one three position manual/off/auto switch next to the filter for each unit at CES. They have to be in AUTO position when we want to turn AC on/off from the lab.

  2841   Mon Apr 26 10:21:45 2010 josephbUpdateLSCStarted dev of LSC FE


Joe and I started working on the new LSC FE control today. We made a diagram of the system in Simulink, but were unable to compile it.

Joe checked out the latest CDS software out of their new SVN and put it somewhere (perhaps his home directory).

The SVN checkout was done on megatron.  It is located under /home/controls/cds/advLigoRTS

So, to compile (or at least try to) you need to copy the .mdl file from /cvs/cds/caltech/cds/advLigo/src/epics/simLink to /home/controls/cds/advLigoRTS/src/epics/simLink on megatron, then run make SYS in the advLigoRTS directory on megatron.

The old checkout from CVS exists on megatron under /home/controls/cds/advLigo.

  2840   Sun Apr 25 10:40:21 2010 KojiUpdateLSCStarted dev of LSC FE

Once you made a CDS model, please update the following wiki page. This will eventually help you.



LSC Plant Model. That is all.


  2839   Sun Apr 25 02:56:07 2010 ranaUpdateLSCStarted dev of LSC FE

LSC Plant Model. That is all.

  2838   Sat Apr 24 15:50:47 2010 KojiUpdatePSLre: 2W Vertical Beam Profile

1. The vertical axis should start from zero. The horizontal axis should be extended so that it includes the waist. See Zach's plot http://nodus.ligo.caltech.edu:8080/40m/2818

2. Even if you are measuring only the linear region, you can guess w0 and z0, in principle. w0 is determined by the divergence angle (pi w0/lambda) and z0 is determined by the linear profile and w0. Indeed your data have some fluctuation from the linear line. That could cause the fitting prescision to be worse.

3. Probably the biggest reason of the bad fitting would be that you are fitting with three parameters (w0, z0, zR) instead of two (w0, z0). Use the relation ship zR= pi w0^2/lambda.

  2837   Sat Apr 24 15:05:41 2010 KevinUpdatePSL2W Vertical Beam Profile

The vertical beam profile of the Innolight 2W laser was measured at eight points along the axis of the laser.

These measurements were made with the laser crystal temperature at 25.04°C and the injection current at 2.091A. z is the distance from the razor blade to the flat black face of the front of the laser.

The voltage from a photodiode was measured for the razor at a number of heights. Except for the first two points, one scan was made with the razor moving down and a second scan was made with the razor moving up. This data was fit to

y = a*erf(sqrt(2)*(x-x0)/w) + b with the following results:

z(cm) (±0.1cm) w(mm) chi^2/ndf
3.9 0.085 ± 0.006 77.09
6.4 0.130 ± 0.004 12.93
8.8 down 0.145 ± 0.008 66.57
8.8 up 0.147 ± 0.008 18.47
11.6 down 0.194 ± 0.010 64.16
11,6 up 0.214 ± 0.009 27.23
14.2 down 0.177 ± 0.008 49.95
14.2 up 0.183 ± 0.007 29.85
16.6 down 0.205 ± 0.006 18.35
16.2 up 0.203 ± 0.007 17.16
19.2 down 0.225 ± 0.007 18.92
19.2 up 0.238 ± 0.011 25.56
21.7 down 0.292 ± 0.006 11.30
21.7 up 0.307 ± 0.008 11.85

The values for w and its uncertainty were estimated with a weighted average between the two scans for the last six points and all eight points were fit to

w = w0*sqrt(1+(z-z0)2/zR2) with the following results:

chi^2/ndf = 17.88

w0 = (0.07 ± 0.13) mm

z0 = (-27 ± 121) mm

zR = (65 ± 93) mm

It looks like all of the data points were made in the linear region so it is hard to estimate these parameters with reasonable uncertainty.

Attachment 1: vbp.jpg
  2836   Fri Apr 23 21:02:14 2010 rana, joeUpdateLSCStarted dev of LSC FE

Joe and I started working on the new LSC FE control today. We made a diagram of the system in Simulink, but were unable to compile it.

Joe checked out the latest CDS software out of their new SVN and put it somewhere (perhaps his home directory).

We then copied the directory with the .mdl files and the CDS parts library into our real Simulink Model Directory:


Use this and not someplace in Alex or Rob's home directory !

Joe will put in more details on Monday once he figures out how to build the new stuff. Basically, we decided not to support multiple versions of the CDS real time code here. We'll just stay synced to the latest stable ~versions.

I exported the current version of the LSC FE into our public_html/FE/ area on nodus where we will put all of the self-documenting FE diagrams:


To make a web setup like this, you just use the "Export to Web" feature from the top-level Simulink diagram (e.g. lsc.mdl). Choose the following options:


Note: in order to get the web page to work, I had to change the apache httpd.conf file to allow AddType file overriding. Here's the term cap of the diff:

nodus:etc>diff httpd.conf httpd.conf~
< ServerAdmin jenne@caltech.edu
> ServerAdmin aso@caltech.edu
<     AllowOverride FileInfo

  2835   Fri Apr 23 18:30:49 2010 Aidan, Jenne, KojiSummaryGreen LockingGreen means GO!

Jenne, Koji and I assembled the Covesion Oven today, inserted a PPKTP crystal from Raicol, aligned the crystal to a 50mW focus and
got some green beam coming out.

Covesion Oven assembly

The oven contains a brass clip that can clamp a crystal up to 10mm wide x 0.5mm high x 40mm long (according to the instructions). According to the correspondence from Covesion the clip can accomodate a crystal up to 1.5mm high. Our crystal is 1mm x 1mm x 30mm.

  1. We removed the brass springs from the clip - see Koji's photos
  2. We placed the Raicol PPKTP crystal (#725) into the clamp with the long polished surfaces facing out to the sides and the roughened surfaces facing up and down.
  3. We balanced the 10mm x 40mm x 1mm glass plate on top of the crystal.
  4. We replaced the brass springs in the top of the clip but only tightened the screws a couple of turns so they wouldn't fall out.
  5. Very carefully and slowly, I tightened the screws a few turns in a star-shaped order to distribute the pressure evenly across the glass top
  6. Each time I tightened all eight screws, I jiggled each of the four springs to see if there was any compression in them
  7. Once the springs started to show signs of compression I stopped tightening them and tested the stability of the glass plate - a reasonable amount of pressure was required to move the plate - about the same amount required to push a SR560 across an optical table with your index finger.
  8. We loosely attached the lid and moved the oven to the table

Alignment of the crystal to the focus

The oven was mounted on a 4-axis Newport translation stage. We plonked the assembly onto the table, removed the lid and adjusted the rough position so that a focus of the 1064nm beam, from a 100mm lens, was positioned near the center of the crystal - then it was clamped down to the table. From here we adjusted the alignment of the stage, using an IR card and a viewer to guide us, until we eventually saw some green beam coming out. We were all very excited by this! We optimized the alignment as best we could using the IR card and then we replaced the lid on the oven. At this point the temperature of the PPKTP was around 26.5C and the green beam coming out look quite dim. We turned the oven up to around 36 degC and observed the beam getting much brighter and we approached the optimum phase-matching condition.

We haven't done anyway quantitative measurements yet but we were pleased with how easy this first stage was.


[Edit by Koji] More photos are on Picasa album

Attachment 1: IMG_2405.jpg
Attachment 2: IMG_2417.jpg
  2834   Thu Apr 22 21:42:24 2010 AlbertoUpdatePSLInnolight 2W Vertical Beam Profile


 What kind of fit did you use? How are the uncertainties in the parameters obtained?

  2833   Thu Apr 22 20:28:40 2010 JenneUpdatePEMSeismometer Noise Characteristics

Quote from elog 2237, 11 Nov 2009:

The attached plot shows the spectra of the 3 Z axes of the 3 seismometers we have (this data is from ~20Aug2009, when the Ranger was in the Z orientation) in Magenta, Cyan and Green, and the noise of each of the sensors in Red, Blue and Black.  The noise curves were extracted from the spectra using the Huddle Test / 3 Corner Hat method.  The Blue and Black traces which are just a few points are estimates of the noise from other spectra.  The Blue points come from the Guralp Spec Sheet, and the Black comes from the noise test that Rana and I did the other day with the Ranger (elog 2223).  

I'm not really happy with the black spectra - it looks way too high.  I'm still investigating to see if this is a problem with my calibration/method....

 So, as it turns out (surprise), I'm a spaz and forgot a 2*pi when calibrating the Guralp noise spectra from the spec sheet.  I noticed this when redoing the Huddle Test, and comparing my Spec Sheet Guralp noise with Rana's, which he shows in elog 2689.  When going from m/s^2, the units in the spec sheet, I just tilted the line by a factor of frequency.  Koji pointed out that I needed a factor of 2*pi*f.  That moves the Guralp spec line in the plot in elog 2237 (to which this entry is a reply) down by ~6, so that my measured noise is not, in fact, below the spec.  This makes things much more right with the world.

In other news, I redid the Huddle analysis of the 2 Guralp seismometers, ala Rana's elog 2689. The difference is now we are on the granite slab, with soft rubber feet between the floor and the granite.  We have not yet cut holes in the linoleum (which we'll do so that we're sitting directly on the 40m's slab).

Rana> this seems horrible. Its like there's a monster in there at 6-7 Hz! Either the seismos are not centered or the rubber balls are bad or Steve is dancing on the granite slab again.


Attachment 1: Gur1_Gur2_noise.png
  2832   Thu Apr 22 15:44:34 2010 josephbUpdateComputers 

I updated the default FILTER.adl file located in /home/controls/cds/advLigo/src/epics/util/ on megatron.  I moved the yellow ! button up slightly, and fixed the time string in the upper right.

Attachment 1: New_example_CDS_filter.png
  2831   Thu Apr 22 09:03:54 2010 steveOmnistructurePEMaircondition can not be turned off

Koji and I wanted to turn off the IFO-room AC so the wind would not blow on MC1-3. We could not. The switches were probably bypassed when the power transformer was replaced at the last scheduled power outage.

  2830   Wed Apr 21 23:35:37 2010 KojiUpdatePSLInnolight 2W Vertical Beam Profile

Good fit. I assumed sqrt(x) is a typo of sqrt(2).


Koji and Kevin measured the vertical beam profile of the Innolight 2W laser at one point.

This data was taken with the laser crystal temperature at 25.04°C and the injection current at 2.092A.

The distance from the razor blade to the flat black face on the front of the laser was 13.2cm.

The data was fit to the function y(x)=a*erf(sqrt(x)*(x-x0)/w)+b with the following results.

Reduced chi squared = 14.07

x0 = (1.964 +-  0.002) mm

w = (0.216 +- 0.004) mm

a = (3.39 +- 0.03) V

b = (3.46 +- 0.03) V


  2829   Wed Apr 21 22:11:48 2010 ranaUpdatePSLInnolight 2W Vertical Beam Profile

Back in Gainesville in 1997, I learned how to do this using the chopper wheel. We had to make the assumption that the wheel's blade was moving horizontally during the time of the chop.

One advantage is that the repetitive slices reduces the random errors by a lot - you can trigger the scope and average. Another advantage is that you can download the average scope trace using USB, floppy, or ethernet instead of pencil and paper.

But, I never analyzed it in enough detail to see if there was some kind of nasty systematic error.

  2828   Wed Apr 21 21:56:27 2010 KevinUpdatePSLInnolight 2W Vertical Beam Profile

Koji and Kevin measured the vertical beam profile of the Innolight 2W laser at one point.

This data was taken with the laser crystal temperature at 25.04°C and the injection current at 2.092A.

The distance from the razor blade to the flat black face on the front of the laser was 13.2cm.

The data was fit to the function y(x)=a*erf(sqrt(x)*(x-x0)/w)+b with the following results.

Reduced chi squared = 14.07

x0 = (1.964 +- 0.002) mm

w  = (0.216 +- 0.004) mm

a  = (3.39  +- 0.03) V

b  = (3.46  +- 0.03) V

Attachment 1: bp2.jpg
Attachment 2: bp2.dat
razor height (mm)   Voltage (V)
2.75    6.89
2.50    6.90
2.30    6.89
2.25    6.89
2.20    6.75
2.15    6.47
2.13    6.20
2.10    6.05
2.07    5.88
... 17 more lines ...
  2827   Wed Apr 21 21:46:53 2010 KojiUpdateIOOMC spot diagnosis

Zach and Koji

We measured uncalibrated angle-to-length coupling using tdssine and tdsdmd.
We made a simple shell script to measure the a2l coupling.


- Opened the IMC/OMC light door.

- Saw the large misalignment mostly in pitch. Aligned using MC2 and MC3.

- Locked the MC in the low power mode. (script/MC/mcloopson AND MC length gain 0.3->1.0)

- Further aligned MC2/3. We got the transmission of 0.16, reflection of 0.2

- Tried to detect angle-to-length coupling so that we get the diagnosis of the spot positions.

- Tried to use ezcademod. Failed. They seems excite the mirror  but returned NaN.

- We used tdssine and tdsdmd instead. Succeeded.

- We made simple shell script to measure the a2l coupling. It is so far located users/koji/100421/MCspot

- We blocked the beam on the PSL table. We closed the chamber and left.


  2826   Wed Apr 21 16:48:38 2010 josephbUpdateCDSHardware update

Alberto and myself went to downs and acquired the 3rd 4x processor (Dual core, so 8x cores total) computer.  We also retrieved 6 BIO interface boards (blue front thin boxes), 4 DAC interface boards, and 1 ADC interface boards.  The tops have not been put on yet, but we have the tops and a set of screws for them.  For the moment, these things have been placed behind the 1Y6 rack and under the table behind the 1Y5 rack


The 6 BIO boards have LIGO travelers associated with them: SN LIGO-S1000217 through SN LIGO-S1000222.

  2825   Wed Apr 21 15:53:57 2010 JenneUpdatePEMSeismometers now on the granite slab

The 3 seismometers are now on the granite slab.  The Ranger is now aligned with the Xarm (perpendicular to the Mode Cleaner) since that's the only way all 3 would fit on the slab.

Attachment 1: P4210048.JPG
  2824   Wed Apr 21 11:32:31 2010 josephbUpdateCDS40m CDS hardware update and software requests

This is mostly a reminder to myself about what I discussed with Jay and Alex this morning.

The big black IO chassis are "almost" done.  Except for the missing parts.  We have 2 Dolphin, 1 Large and 1 Small I/O Chassis due to us.  One Dolphin is effectively done and is sitting in the test stand.  However, 2 are missing timing boards, and 3 are missing the boards necessary for the connection to the computer.  The parts were ordered a long time ago, but its possible they were "sucked to one of the sites" by Rolf (remember this is according to Jay).  They need to either track them down in Downs (possibly they're floating around and were just confused by the recent move), get them sent back from the sites, or order new ones (I was told by one person that the place they order from them notoriously takes a long time, sometimes up to 6 weeks.  I don't know if this is exaggeration or not...).  Other than the missing parts, they still need to wire up the fans and install new momentary power switches (apparently the Dolphin boards want momentary on/off buttons).  Otherwise, they're done.

We are due another CPU, just need to figure out which one it was in the test stand.

6 more BIO boards are done.  When I went over the plans with Jay, we realized we needed 7 more, not 6, so they're putting another one together.  Some ADC/DAC interface boards are done.  I promised to do another count here, to determine how many we have, how many we need, and then report that back to Jay before I steal the ones which are complete.  Unfortunately, he did not have a new drawing for the ASC/vertex wiring, so we don't have a solid count of stuff needed for them.  I'll be taking a look at the old drawings and also looking at what we physically have.

I did get Jay to place the new LSC wiring diagram into the DCC (which apparently the old one never was put in or we simply couldn't find it).  Its located at: https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=10985

I talked briefly with Alex, reminded him of feature requests and added a new one:

1) Single part representing a matrix of filter banks

2) Automatic generation of Simulated shared memory locations and an overall on/off switch for ADC/DACs

3) Individual excitation and test point pieces (as opposed to having to use a full filter bank).  He says these already exist, so when I do the CVS checkout, I'll see if they work.


I also asked where the adl default files lived, and he pointed me at ~/cds/advLigo/src/epics/util/

In that directory are FILTER.adl, GDS_TP.adl, MONITOR.adl.  Those are the templates.  We also discovered the timing signal at some point was changed from something like SYS-DCU_ID to FEC-DCU_ID, so I basically just need to modify the .adl files to fix the time stamp channel as well.  I basically need to do a CVS checkout, put the fixes in, then commit back to the CVS.  Hopefully I can do that sometime today.

I also brought over 9 Contec DO-32L-PE boards, which are PCIe isolated digital output boards which do into the IO chassis.  These have been placed above the 2 new computers, behind the 1Y6 rack.


  2823   Wed Apr 21 10:09:23 2010 kiwamuUpdateGreen Lockingwaist positon of Gaussian beam in PPKTP crystals

Theoretically the waist position of a Gaussian beam (1064) in our PPKTP crystal differs by ~6.7 mm from that of the incident Gaussian beam.

So far I have neglected such position change of the beam waist in optical layouts because it is tiny compared with the entire optical path.

But from the point of view of practical experiments, it is better to think about it.

In fact the result suggests the rough positioning of our PPKTP crystals;

we should put our PPKTP crystal so that the center of the crystal is 6.7 mm far from the waist of a Gaussian beam in free space.

(How to)

The calculation is very very simple.

The waist position of a Gaussian beam propagating in a dielectric material should change by a factor of n, where n is the refractive index of the material.

In our case, PPKTP has  n=1.8, so that the waist position from the surface of the crystal becomes longer by n.

Now remember the fact that the maximum conversion efficiency can be achieved if the waist locates at exact center of a crystal.

Therefore the waist position in the crystal should be satisfied this relation; z*n=15 mm, where z is the waist position of the incident beam from the surface and 15 mm is half length of our crystal.

Then we can find z must be ~8.3 mm, which is 6.7 mm shorter than the position in crystal.

The attached figure shows the relation clearly. Note that the waist radius doesn't change.

Attachment 1: focal_positin_edit.png
  2822   Tue Apr 20 20:15:37 2010 KevinUpdatePSLInnolight 2W Output Power vs Injection Current

Koji and Kevin measured the output power vs injection current for the Innolight 2W laser.

The threshold current is 0.75 A.


The following data was taken with the laser crystal temperature at 25.04ºC (dial setting: 0.12).

Injection Current (A) Dial Setting Output Power (mW)
0.000 0.0 1.2
0.744 3.66 1.1
0.753 3.72 4.6
0.851 4.22 102
0.954 4.74 219
1.051 5.22 355
1.151 5.71 512
1.249 6.18 692
1.350 6.64 901
1.451 7.08 1118
1.556 7.52 1352
1.654 7.92 1546
1.761 8.32 1720
1.853 8.67 1855
1.959 9.05 1989
2.098 9.50 2146


Attachment 1: PvsI_2W.jpg
  2821   Tue Apr 20 19:37:02 2010 KojiUpdateGreen Locking1W NPRO output profile

Beautiful fitting.


EDIT: I used an IFIT (inverse fast idiot transform) to change the x-axis of the plot from Hz to m. I think xlabel('Frequency [Hz]') is in my muscle memory now..

I have redone the beam fit, this time omitting the M2, which I believe was superfluous. I have made the requested changes to the plot, save for the error analysis, which I am still trying to work out (the function I used for the least squares fit does not work out standard error in fit parameters). I will figure out a way to do this and amend the plot to have error bars.



  2820   Tue Apr 20 18:02:22 2010 JenneUpdateCOCNew SRM and PRM Hung

[Jenne, Steve]

We removed the old SRM and PRM from their cages, and are temporarily storing them in the rings which we use to hold the optics while baking.  Steve will work on a way to store them more permanently.

We then hung the new SRM (SRMU03) and new PRM (SRMU04) in the cages.  We were careful not to break the wires, so the heights will not have changed from the old heights.

The optics have not been balanced yet.  That will hopefully happen later this week.

  2819   Tue Apr 20 13:37:36 2010 JenneUpdateGreen Locking1W NPRO output profile


I have redone the beam fit, this time omitting the M2, which I believe was superfluous. I have made the requested changes to the plot, save for the error analysis, which I am still trying to work out (the function I used for the least squares fit does not work out standard error in fit parameters). I will figure out a way to do this and amend the plot to have error bars.


 Are you sure about your x-axis label? 

  2818   Tue Apr 20 13:02:14 2010 ZachUpdateGreen Locking1W NPRO output profile

EDIT: I used an IFIT (inverse fast idiot transform) to change the x-axis of the plot from Hz to m. I think xlabel('Frequency [Hz]') is in my muscle memory now..

I have redone the beam fit, this time omitting the M2, which I believe was superfluous. I have made the requested changes to the plot, save for the error analysis, which I am still trying to work out (the function I used for the least squares fit does not work out standard error in fit parameters). I will figure out a way to do this and amend the plot to have error bars.

  2817   Tue Apr 20 13:00:52 2010 ZachUpdateelogelog restarted

 I restarted the elog with the restart script as it was down.

  2816   Tue Apr 20 11:14:31 2010 AidanUpdateGreen LockingRaicol crystals arrived and we investigated them


 Here is Crystal 724 polished side 2 with all photos along the length stitched together

  2815   Tue Apr 20 10:55:10 2010 steveBureaucracySAFETYKevin Kuns received safety training

The 40m's new undergrad Kevin Kuns was introduced to 40m safety hazards. He is new and needs guidance as specially with 2W laser work.

Peter King will train him on Friday to LIGO-laser standard.


  2814   Tue Apr 20 09:15:15 2010 steveSummarySAFETYannual safety audit
Attachment 1: safa.PDF
  2813   Tue Apr 20 08:00:52 2010 steveUpdateSUSETMY damping restored

ETMY sus damping was restored

  2812   Tue Apr 20 07:48:42 2010 steveUpdatePSLion pump HV turned on

We found ref-cavity HV was off yesterday afternoon. It was turned back on.

  2811   Tue Apr 20 00:32:30 2010 JenneUpdatePEMGuralp Breakout Box put back


I pulled the Guralp breakout box from the rack, and it's sitting on the EE bench here.  The game plan is to check out the Gur2X channel.  

Rana and Steve have been investigating, and found that the X channel has been funky (which has been known for ~a month or two) when the seismometer has been plugged in, and also when the seismometers have been unplugged, but the box is left on.  The funkyness goes away when the box is turned off.  Since it's not there when the box is off, it seems that it's not a problem with the cable from the box to the ADC, or in the ADC channel.  Since it is there when the box is on, but the seismometer is unplugged, it's clear that it's probably in the box itself.  

Preliminarily, I've connected a set of BNC clipdoodles to the input testpoints, and another set to the output.  They're both connected to a 'scope (which is on it's battery so it's not connected to any Ground), and when I tap on the circuit board the input trace is totally unchanged, but the output trace goes kind of crazy, and gets more fuzzy, and picks up a DC offset.  Koji is concerned that some of the big capacitors may have an iffy connection to the board. 

Investigations will continue Monday morning. 

 The Guralp Box appears to be back in working order.  It's reinstalled with the 2 seismometers plugged in.

In order:

* Koji suggested retouching the through-board solder joints on the broken channel (EW2 = Gur2X) with a bit of solder to ensure the connections were good.  Check.

* "C7", one of the giant 1uF capacitors on each channel is totally bypassed, and since that was one of the original suspects, Rana removed the (possibly) offending capacitor from EW2.

* Rana and I isolated the craziness to the final differential output stage.  We tried each of the testpoints after the individual gain / filter stages, and found that the signals were all fine, until after the output stage.

* I started to remove the resistors in the output stage (with the plan to go through the resistors, capacitors, and even the amplifier chip if neccessary), and noticed that 2 of the 1k resistors came off too easily, as if they were just barely connected in the first place.  After replacing only the 4 1k resistors, the craziness seemed to be gone.  I poked and gently bent the board, but the output wouldn't go crazy.  I declared victory.

* I reinstalled the box in its normal spot, and put Gur2 (which had been out by the bench for use as a test signal) back next to the other seismometers.  We are in nominal condition, and should be able to do a huddle test this week.


I looked at the time traces of all the seismometer channels, and they all looked good.  I'll put a spectra in in the morning....I'm too impatient to wait around for the low frequency FFTs.


Attached are the before and after pictures of the output stage of EW2 / Gur2X.  The "before" is the one with the OUT+ and OUT- words upsidedown.  The "after" picture has them right side up.

Attachment 1: Gur2X_before_20Apr2010.jpg
Attachment 2: Gur2X_after_replace_100k_resistors_20Apr2010.jpg
  2810   Mon Apr 19 16:31:42 2010 KevinUpdatePSLInnolight 2W Laser

Koji and Kevin

We unpacked the Innolight 2W laser, took an inventory, and scanned the operations manual.

[Edit by KA]

The scanned PDFs are placed on the following wiki page


We will measure the P-I curve, the mode profile, frequency actuator responses, and so on.

  2809   Mon Apr 19 16:27:13 2010 AidanUpdateGreen LockingRaicol crystals arrived and we investigated them

Jenne, Koji and I opened up the package from Raicol and examined the crystals under the microscope. The results were mixed and are summarized below. There are quite a few scratches and there is residue on some of the polished sides. There is a large chip in one and there appear to be gaps or bands in the AR coatings on the sides.

There are two albums on Picassa

1. The package is opened ...

2. The crystals under the microscope.


Crystal Summary
724 Chip in the corner of one end face, Otherwise end faces look clean. Large scratch on one polished side.
725 End faces look good. Moderate scratch on one polished face. Residue on one polished face.
726 Tiny dot on one end face, otherwise look okay. Large bands in one polished face. Moderate scratch on polished face
727 Large, but shallow chip on one polished face. End faces look clean. Bands in one of the polished faces.


  2808   Mon Apr 19 13:23:03 2010 josephbConfigurationComputersyum update fixed on control room machines

I went to Ottavia, and tried running yum update.  It was having dependancy issues with mjpegtools, which was a rpmforge provided package.  In order to get it to update, I moved the rpmforge priority above (a lower number) that of epel ( epel -> 20 from 10, rpmforge -> 10 to 20).  This resolved the problem and the updates proceeded (all 434 of them). yum update on Ottavia now reports nothing needs to be done.

I went to Rosalba and found rpmfusion repositories enabled.  The only one of the 3 repositories in each file enabled was the first one.

I then added priority listing to all the repositories on Rosalba.  I set CentOS-Base and related to priority=1.  I set CentOS-Media.repo priority to 1 (although it is disabled - just to head off future problems). I set all epel related to priorities to 20. I set all rpmforge related priorities to 10.  I set all rpmfusion related priorities to 30, and left the first repo in rpmfusion-free-updates and rpmfusion-nonfree-updates were enabled.  All other rpmfusion testing repositories were disabled by me.

I then had to by hand downgrade expat to expat-1.95.8-8.3.el5_4.2.x86_64 (the rpmforge version).  I also removed and reinstalled x264.x86_64.  Lastly I removed and reinstalled lyx. yum update was then run and completed successfully.

I installed yum-priorities on Allegra and made all CentOS-Base repositories priority 1. I similarly made the still disabled CentOS-Media priority 1.  I made all epel related repos priority 20.  I made all lscsoft repos priority=50 (not sure why its on Allegra and none of the other ones).  I made all rpmforge priorities 10.  I then ran "yum update" which updated 416 packages.


So basically all the Centos control room machines are now using the following order for repositories:

CentOS-Base > rpmforge > epel > (rpmfusion - rosalba only) > lscsoft (allegra only)

I'm not sure if rpmfusion and lscsoft are necessary, but I've left them for now.  This should mean "yum update" will have far fewer problems in the future.


  2807   Mon Apr 19 11:31:04 2010 AidanUpdateGreen Locking1W NPRO output profile


 Koji asked me to take a profile of the output of the 1W NPRO that will be used for green locking. I used the razor-scan method, plotting the voltage output of a PD vs the position of the razor across the beam, both vertically and horizontally. This was done at 6 points along the beam path out of the laser box.

I determined the beam spot size at each point by doing a least-squares fit on the plots above in Matlab (using w as one of the fitting parameters) to the cumulative distribution functions (error functions) they should approximate.

I then did another least-squares fit, fitting the above "measured" beam profiles to the gaussian form for w vs z. Below is a summary.

It seems reasonable, though I know that M2 < 1 is fishy, as it implies less divergence than ideal for that waist size. Also, like Koji feared, the waist is inside the box and thus the scan is almost entirely in the linear regime.


There is a clearly a difference in the divergence angle of the x and y beams - maybe 10-20%. Since the measurements are outside the Rayleigh range and approximately in the linear regime, the slope of the divergence in this plot should be inversely proportional to the waists - meaning the x- and y- waist sizes should differ by about 10-20%. You should check your fitting program for the waist.


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