NAOJ GW Elog Logbook 3.2
I learned using COMSOL Multiphysics 5.1. I made a model of the sample in 2D with axisimmetric revolution around the pump beam axis. I built a thin rectangle for the absorbing coating (10 micron) and a thick rectangle for the substrate (3mm). The mesh is fine (1micron) near the heat source and in the coating, and coarse (0.5mm) far from the center (see the picture mesh.png). The heat source is a gaussian beam of size 70micron and power 1W. The absorption ratio is 12ppm. Chopper frequency is 430Hz but the waveform is a sine, because I'm going to compare this solution with the analitic solution which has a sine waveform instead of a square one. I attach the plot of the temperature of the point (r,z)=(0,0) as a function of time for 100 ms. And an animation of the temperature distribution. with the color scale in kelvin. I cannot upload the file and I don't understand why. It is a gif file and it's less than 10Mb. this is the link to my dropbox: https://www.dropbox.com/s/gd28tb1zc7gxdob/movie.gif?dl=0
Two viewport windows on the gate valve (GVs) between the MCF and IFI chambers are changed with new glasses with AR-coated as planned.
With this work, AOS has finished to change all the windows on the exsiting GVs in KAGRA to the AR-coated ones (10 pieces of windows in total).
This is a small milestone for AOS.
The details of the AR-coated windows are fonud in
http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2926
We brought the IM parts into the clean room.
The parts are on the green rack where the bottom filters sit below.
Two sets of the IM parts are brought inside except for the picomotors and bottom mass compensation parts.
And the some of the wire clamping do not have the same numbers on them because the clamping parts are not packed with same numbers.
We can assemble one set of IM with the parts inside, but please check the numbers on the clamping parts when you assemble the second IM.
Since the laser, which is currently used for the JASMINE scatterometer, features a far too high spreading of its width, I installed a lens to refocus the beam toward the sample.
This focussing had to be measured and compared with the theoretical development of the width (the beam should be Gaussian).
The result is satisfying as the theoretical curves mach the measured values within averaged errors of less than 5%.
It should be noted that the beam has two different width distrubutions, perpendicular to each other, which I denominate X and Y.
In the attached figure the development along a lenght-axis (the way of the laser) is shown with indicated positions of the laser, a mirror (this is the point zero, for practical reasons), and the used lens (f=200mm).
On the left side of the lens, the measured values of the laser widths as the laser produces them are shown (dots). They were fitted with the respective Gaussian beam development w(z) (lines).
On the right side of the lens, the measured values of the focussed laser widths are shown (again in dots), together with the theoretical development (lines), calculated out of the parameters as given by the fits of the left-side beams.
For the scatterometer itself, the sample is located approximately 27 - 28 cm away from the lens. The width should, thus, be in the range of 0.13 - 0.17 mm.
Installation movies on 28th July 2015 are linked from the following page.
http://gwclio.icrr.u-tokyo.ac.jp/lcgtsubgroup/inoutoptics/2015/07/installation-of-a-laser-guidance-duct.html
http://gwclio.icrr.u-tokyo.ac.jp/lcgtsubgroup/inoutoptics/2015/07/start-installation-of-a-laser-guidance-duct.html
Installation movies on 28th July 2015 are linked from the following page.
http://gwclio.icrr.u-tokyo.ac.jp/lcgtsubgroup/inoutoptics/2015/07/installation-of-a-laser-guidance-duct.html
By Sakakibara-kun.
Locations of the iKAGRA beam dumps, so far around MCF and MCE, or rather ghost beams, are described here.
http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3900
Recently, Hirose-san gave me the measured surface maps of the PR3, PR2, SR3, and SR2 mirrors.
Since there were no PSD calculations yet, I did these with a scilab program that I have written for this purpose.
The results can be seen in the picture that is attached, together with the PSD of the beam splitter as comparison.
Obviously, all PSDs are not so different from each other which might be a good sign.
I did some measurements with a new device in the ATC for creating surface maps together with Ezaki-san and Flaminio-san.
We measured the roughnesses of surfaces of SiO2-glass, a sapphire plate and a GaAs-wafer.
The results are still in a raw-data format and I need some calculations first to give an overview.
I made maps of the LMA surface sample with
High resolution 70 micron of spacing (as the dimension of the pump beam).
Calibration factor used R=13 1/W.
Scan areas are 4mm x 3mm.
LMA sample 15034
nominal absorption = 0.65ppm
pump power = 6.3W
map mean = 5ppm (including very high spiky noise or dust or scratch)
most of area value = 0.85ppm
LMA sample 15032
nominal absorption = 4.5ppm
pump power = 3.36W
map mean = 17ppm (including very high spiky noise or dust or scratch)
most of area value = 5.4ppm
LMA sample 15033
nominal absorption = 12.8ppm
pump power = 1.18W
map mean = 20ppm (including very high spiky noise or dust or scratch)
most of area value = 14ppm
I made again a map of the same area of the LMA sample 15034. In the same conditions. I didn't unmount the sample from the holder, but I noticed that after one week it was dusty. So I cleaned it again with the first contact polymer. I show the picture of before and after cleaning. I show the comparison of the same measurement in the same conditions but after a week and a cleaning.
The 30 pieces of the coil bodies are "doubly" packed into clean polyethylene packs (made in a class-100 room, the provider said) in the ATC ISO-1 clean booth. Will be sent to KEK soon.
I found the solution to the heat equation in this article and I calculated numerically using Matlab.
I show the solution of the heat equation for an absorbing fused silica medium.
- oscillating pump gaussian beam size 70micron
- oscillation frequency 430Hz
- absorbing thickness 10micron
- absorbed power 0.1mW
- fused silica thermal parameters
- scale in Kelvin
I made two resolved maps of the entire surface of the reference sample (200micron scan step) where the surface is behind the pump (flipped sample). One scanning along X axis (left in the image) and one scanning along Y axis. It shows that there are little fluctuations and they are a bit larger perpendicular to the scan axis. This happens for both maps. This means there are some long time power fluctuations. Maybe it shows more clear in the second attached image where there is only a 2D map.
There is also a relevant difference between the center of the sample and near the edge, the maximum is near the center, and the difference depends on the map. Still to be understood.
Four 30 out of 36 washed pieces of the OSEMs, the coil wires are fixed to their bodies by a vac seal, and now being cured (for one or two days) in the ATC ISO-1 clean booth. I need more vac seals.
I use nozzles but the viscosity of the vac seal is so high that my grip now reduces forces..
The 30 pieces of the coil bodies are "doubly" packed into clean polyethylene packs (made in a class-100 room, the provider said) in the ATC ISO-1 clean booth. Will be sent to KEK soon.
The Remaining 37 OSEMs are now being cured in the ISO-1 clean booth in the ATC multipurpose experimental room!
Don't touch them for a couple of days.
Previously I did this 30 OSEM coils, and today 37coils, that means there will be 67 OSEMs in total. The number is sufficient for iKAGRA, but not for bKAGRA, as at least 70 OSEMs will be required for the bKAGRA (PRM, PR2, PR3, BS, SRM, SR2, SR3).
There are some OSEM coils washed or unwashed and used for trials of several process for the assembly, and they should be added to the number to fulfill the required numbers.
37 OSEM coil bodies are now packed into clean bags. (Akutsu, Fujii)
Plus 5 OSEM coil bodies are washed (by ethanol), and then 67+5 = 72 OSEM coil bodies will be available in the end.
I measured some maps of the Surface reference sample.
I order to compare and join different areas of the sample and in order to process datas I wrote a matlab script that read the .txt file the program uses to store measurements datas.
The map is made scanning many lines, the scan direction used here is the X axis. In the plot we can see some fluctuations that are bigger alog the Y axis. My guess is that long time fluctuations of the pump power cause this. We can also recognize the edge of the sample by the lowest signal at (x,y)=(36,30.5)
I made two resolved maps of the entire surface of the reference sample (200micron scan step) where the surface is behind the pump (flipped sample). One scanning along X axis (left in the image) and one scanning along Y axis. It shows that there are little fluctuations and they are a bit larger perpendicular to the scan axis. This happens for both maps. This means there are some long time power fluctuations. Maybe it shows more clear in the second attached image where there is only a 2D map.
There is also a relevant difference between the center of the sample and near the edge, the maximum is near the center, and the difference depends on the map. Still to be understood.
I wanted to understand the big difference between the absorption peak in the configuration where the pump is entering in the sample by the absorbing surface and the other configuration where the pump is entering the sample by the not absorbing surface (flipped sample). So I made again a calibration and also a calibration with the flipped surface reference sample and I found a calibration factor R=17 1/W (flipped) and R=13 1/W (not flipped). For the not flipped sample I made a calibration history in this post and I found a mean calibration factor R=11 1/W with fluctuatoins of 10%. I don't understand why R changes so much.
If we calculate the LMA15033 absorption with those R factors we get 22ppm for the flipped surface and 14ppm for the not flipped surface.
I conclude that the recommended wedge angle is 20m rad.
Akutsu and Takahashi washed 36 pieces of OSEM coil bodies with acetone in a ultrasonic bath. They are now located at the ATC ISO-1 clean booth to dry. Later, Akutsu will put vac seals to the coil to fix the wire edges, and pack into clean bags, and send to KEK for baking.
The number is just determined by the fact (1) PR2, 3, BS OSEMs are urgent, so 30 pieces are needed, (2) the ultrasonic bath can contain 12 pieces at once.
- Five pieces of the OSEM coil bodies (wires are wounded) are washed with acetone in a ultrasonic bath (40degC, 20mins). The wires' edges are not fixed to the coil body because Takahashi-san pointed out that the vac seal could be removed by acetone.
- A PD(S1223-01) and a LED (TSTS7100) are also washed in the same manner. I'll check if their performance would decrease (increase?) or not.
Results
Conditions:
- The washed and non-washed PDs are different ones.
- The same LED's intensity noises are measured before and after the wash.
The attached graph shows the washing would not affect the performance; it's only one sample, so we still lack a statistics, but we can probably say they can tolerate the ultrasonic washing.
About the PDs, noises with PDs are the same level as the 35670A at their inpur ranges. The mechanism why the input ranges are different for the two measurements are unknown, but one thing: the Okt circuit and LEDs and PDs are connected by crocodile clips (alligator clip, whatever), and the noise level is very senstive to the arrangement of these wires!
According to the graph, it appears the washed one becomes better than unwashed one, but the measurement are the same level as the measurement noises, so we cannot say such things.
