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KAGRA AOS (General)
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SimonZeidler - 22:52, Tuesday 08 December 2015 (206)Get code to link to this report
Offset in back-scatterometer?

A gap between the data of VB measured with our back-scatterometer and the data provided by SurreyNanoSystems made me curious about a possible offset in our data (our data were constantly 10 x higher). So I searched for systematical errors and ended up on the beam-splitter. It seems that by illuminating it with the laser, the PD gets a signal of 0.252nA even when the backscattering is cut of.

My interpretation is that this additional signal is actually scattering from the beam-splitter.

I am now thinking how we can get rid of this influence without violating the SNR too much severely.

R&D (FilterCavity)
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EleonoraCapocasa - 20:41, Friday 27 November 2015 (205)Get code to link to this report
Change of double pendulum suspension

Workers: Eleonora and Tatsumi

 

Today we replaced the double pendulum installed in NM2 vacuum tank with the one used to suspend the TAMA power recycling mirror (placed In RM vacuum chamber)

Power recycling mirror was still suspended and we succeded in moving the suspension with the mirrorr hanged. In the next days we planned to take a spectrum of the mirror motion to check the effectiveness of the stack and suspension system.

We also started preparing an optical lever needed to measure this spectrum.

Images attached to this report
205_20151127123741_1.png 205_20151127123759_2.png
R&D (FilterCavity)
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EleonoraCapocasa - 19:18, Tuesday 17 November 2015 (204)Get code to link to this report
Vibration isolation system installation

Workers: Eleonora, Tatsumi, Takahashi

Today we completed the installation of the vibration isolation system needed to suspend the filter cavity input mirror in the NM2 vacuum tank.

Such a system is composed by (from bottom to top):

  1. A baseplate (see picture 1)
  2. A three layer stack made of rubber and metal blocks (see picture 2)
  3. A top-plate
  4. A double pendulum system

In picture 3 the empty bottom of the vacuum tank is showed while in picture 4 the complete system can be seen.

Some test of vibration isolation are planned for the next days.

Images attached to this report
204_20151117111300_1.png 204_20151117111304_2.png 204_20151117111310_3.png 204_20151117111315_4.png
R&D (FilterCavity)
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EleonoraCapocasa - 17:34, Monday 16 November 2015 (203)Get code to link to this report
TAMA SAS system removed from NM2 vacuum tank

Workers: Eleonora and Tatsumi

Today current TAMA SAS system has been safely removed from NM2 vacuum tank. The vibration isolation system to be installed at its place is currently placed in PD vacuum tank ( e-log 201) and can be now moved in NM2 vacuum tank.

KAGRA AOS (General)
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SimonZeidler - 20:00, Friday 13 November 2015 (202)Get code to link to this report
VB measurements

I have measured the new VB-S sample and again the original VB-plate in order to compare these two.
Surprisingly, the VB-S sample is more "black" than the original sample although the other way around should have been occured. Also, it seems that the VB-plate-blackness altered when comparing this with a measurement from January...

In all these, I have to add that the data in the measurement from January may be not comparable as the system was still under reconstruction at that time. Also, as it is the first time for me to use Torii-sans setup, I am not sure whether there is still a mistake in the absolute values...

Images attached to this report
202_20151113120031_beamdumper.jpg
R&D (FilterCavity)
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EleonoraCapocasa - 14:37, Friday 13 November 2015 (201)Get code to link to this report
Preparation for vibration isolation system installation in NM2 vacuum tank.
Workers: Tatsumi and Eleonora


We star by checked the double-pendulum system which were moved form warehouse to TAMA central room.
We found that coil mass and electric cable were missing (fig 1-2).

We opened PD vacuum chamber and we found a completely assembled isolator stack with a double-pendulum system (fig 3).
(It was meant to be used to suspend a signal recycling mirror in TAMA.)

We checked this system too and we found that just the electric connectig cable was missing.

Since this vibration isolation system (both double pendulum and stack isolator) is in a better condition than the one stored in the warehouse,
we planned to use this one for suspending filter cavity input mirror in NM2 vacuum tank.

In order to do that, we checked that system dimensions were compatible with the ones needed for NM2 tank (fig 4-5).

Next week we will remove current TAMA SAS system from NM2 vacuum tank and we will replace it with the vibration isolation system at present placed in PD vacuum chamber.
Images attached to this report
201_20151113063125_1.jpg 201_20151113063133_2.jpg 201_20151113063146_3.jpg 201_20151113063153_4.jpg 201_20151113063200_5.jpg
R&D (FilterCavity)
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DaisukeTatsumi - 17:35, Wednesday 11 November 2015 (200)Get code to link to this report
Preparations for TAMA SAS system removal

On 11 November, we finished the following works.

 
[Workers] Eleonora, Ishizaki, Tatsumi
[WORKERS] Eleonora, Ishizaki, and Tatsumi

1)  fixing the TAMA SAS system,

2)  unscrewing TAMA SAS system from the bottom of the vacuum tank. and

3)  we found a hanging frame for TAMA SAS system at TAMA west-end room.

      Ishizaki-san will move it to TAMA center room.

4)  a double-pendulum system and bottom plate of the stack isolator

      were moved from warehouse to TAMA center room.

Now TAMA SAS system is ready to remove.

Non-image files attached to this report
R&D (FilterCavity)
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DaisukeTatsumi - 19:07, Monday 09 November 2015 (199)Get code to link to this report
Preparation work for TAMA SAS from NM2 vacuum tank

Workers: Eleonora, Tatsumi

Non-image files attached to this report
R&D (FilterCavity)
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DaisukeTatsumi - 16:56, Wednesday 04 November 2015 (198)Get code to link to this report
TAMA NM2 vacuum tank exposure

[ WORKERS ] Tatsumi and Takahashi

We opened the tank and then check TAMA SAS system

to remove from the tank.

 

You can find the procedure to air explosure of NM2 tank

bellow.

Non-image files attached to this report
KAGRA AOS (General)
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SimonZeidler - 18:47, Monday 02 November 2015 (197)Get code to link to this report
SiC Surface Measurements

I did again measurements on the surfaces of some new SiC samples.
The number of samples this time was 6 from two companies: 3 samples from "NihonFineCeramics" and 3 samples from "Coorstek".

The average surace height distribution (Sa) has been found with Zygos NewView instrument to be 10 ~ 12 nm, for all samples. The measured window has been chosen to be 3x3 mm (2.5x mag.). Thus, the resolution is not particular high. Therefore, and also as we found some irregularities in the measured Sa values at higher resolutions (50x mag.), we made an additional measurement with the AFM in ATC on a randomly chosen spot of the third sample from "Croostek". The determined value of Sa with the AFM is 16.2 nm.

Attached to this report are the taken pictures of the height profiles. The first three are from "Croostek", the other three from "NihonFineCeramics". In black/white, the AFM picture is shown.

Images attached to this report
197_20151102104638_siccoorstek1.bmp 197_20151102104643_siccoorstek2.bmp 197_20151102104648_siccoorstek3.bmp 197_20151102104654_sicjgw1.bmp 197_20151102104659_sicjgw2.bmp 197_20151102104704_sicjgw3.bmp 197_20151102104720_sic.jpg
KAGRA MIR (Absorption)
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ManuelMarchio - 18:27, Tuesday 20 October 2015 (196)Get code to link to this report
Comment to GaAs absorption measurement at Spectrophotometer (Click here to view original report: 193)

I used the Fresnel laws to determine wether or not the angle 12° would affect the Reflection measurement.

If the light was polarized the difference between 12° and 0° would be 2.5%

But the spectrophotometer SolidSpec-3700 have unpolarized light, and the difference between 12° and 0° is a factor of 1.5e-5 (0.0015%).

Not enough to affect the measurement, unless the light was polarized for some reason.

KAGRA VIS (Mirror Assemble)
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ManuelMarchio - 15:02, Monday 19 October 2015 (195)Get code to link to this report
PR3 glueing work at Kashiwa

Members: Tatsumi-san, Manuel

Before making the glueing work it is necessary to pour First Contact polymer on the central area of mirror surface. We tried to do that but we had some troubles. I attach the pictures to show the problem. If the flow from the bottle is not continuous, the liquid splatters around and so we got some droplets in the area which is not to be covered by FirstContact. So we had to add FirstContact on the droplets and peel it up to clean them. The droplets went also on the edge and we had to apply the FirstContact with a brush. and using a smaller bottle. 

Images attached to this report
195_20151019074309_newpa160174.jpg 195_20151019074327_newpa160175.jpg 195_20151019074351_newpa160176.jpg 195_20151019075255_newpa160177b.jpg 195_20151019075333_newpa160182.jpg 195_20151019075434_newpa160183b.jpg 195_20151019075528_newpa160184b.jpg 195_20151019075635_newpa160185b.jpg 195_20151019075728_newpa160186b.jpg 195_20151019075815_newpa160188b.jpg 195_20151019075924_newpa160190b.jpg 195_20151019080029_newpa180192b.jpg 195_20151019080057_newpa180191.jpg 195_20151019080107_newpa180193.jpg
KAGRA MIR (Absorption)
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ManuelMarchio - 12:05, Monday 19 October 2015 (194)Get code to link to this report
Comment to GaAs simulation: correction factor between bulk and surface absorption (Click here to view original report: 177)

I plot the same thing in a wider range, up to 5cm or radius to see how the graph goes to zero.

In the second figure I take the second derivative of the optical path with respect to the radius. The second derivative should de proportional to the focusing power, hence, to the signal of the absorption system.

It is the same for the bulk and for the surface absorption

Images attached to this comment
194_20151019050514_gaascfr5cm.png 194_20151019050522_gaascfr2ndderivative.png
KAGRA MIR (Absorption)
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ManuelMarchio - 00:17, Saturday 17 October 2015 (193)Get code to link to this report
GaAs absorption measurement at Spectrophotometer

I measured 3 samples of GaAs wafer from LMA.

Reflection measurement is taken at 12°.

Light is not polarized.

Plots show the spectrum of Transmission, Reflection and Absorption ( A = 100% - T - R ).

At 1064nm the absorption is about 4%. After 1300nm absorption becomes negative, down to -2%.

Images attached to this report
193_20151016171144_screenshotfrom20151016232044.png 193_20151016171200_screenshotfrom20151016232001.png 193_20151016171211_screenshotfrom20151016231917.png
Comments related to this report
ManuelMarchio - 18:27, Tuesday 20 October 2015 (196)

I used the Fresnel laws to determine wether or not the angle 12° would affect the Reflection measurement.

If the light was polarized the difference between 12° and 0° would be 2.5%

But the spectrophotometer SolidSpec-3700 have unpolarized light, and the difference between 12° and 0° is a factor of 1.5e-5 (0.0015%).

Not enough to affect the measurement, unless the light was polarized for some reason.

KAGRA VIS (Mirror Assemble)
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DaisukeTatsumi - 08:04, Friday 16 October 2015 (192)Get code to link to this report
Cross-checking for Shoda-san's measurements

I made cross-checkings for Shoda-san's measuremets of "SPARE MIRROR" at Kagra site.

 

1) OSEM flag position on mirror

Within the accuracy of 1mm, these measurements are almost consistent with the design.

Only a measured value of the upper edge of the mirror was wrong.

 

2) Relative position of OSEM flag respect to the through-hole

After the hanging, it seems that the mirror is placed on 6mm upside from the mirror box.

I confirm it by making a drawing as attached.

Non-image files attached to this report
KAGRA VIS (OSEM)
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TomotadaAkutsu - 22:17, Saturday 10 October 2015 (182)Get code to link to this report
Comment to Fixing coil wires to OSEM coil bodies by a vac seal (Click here to view original report: 137)


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.




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182_20150922133514_img0111.jpg
KAGRA MIR (Absorption)
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ManuelMarchio - 23:30, Tuesday 06 October 2015 (191)Get code to link to this report
Tama-sized mirror mount drawing

I draw on Inventor the mirror mount for the tama-sized mirrors (d100 x 60).

The picture shows the transation stage part where the mount have to be fixed.

I attach a pdf of the drawing (actually, the top view shouldn't be red, it's a problem of the conversion to pdf, so I also attach the bitmap of the topview). 

The yellow part is peek plastic, which is in contact with the mirror.

The red part is the part that have to be fixed permanently to the translation stage.

I put a precision pin, to attach the mirror mount always in the same position.

Images attached to this report
191_20151006161436_topview.bmp 191_20151006163032_btsplate.jpg
Non-image files attached to this report
KAGRA AOS (General)
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SimonZeidler - 17:58, Friday 02 October 2015 (190)Get code to link to this report
Simulations regarding light-scattering of BS recoil mass

I finished the (final?) simulations regarding the scattering of the BS recoil mass with the revised model of the BS, which I got from Fabian.

Basically, as expected, no significant effect could be found on KAGRAs sensitivity.

However, I have widen the previous model with the view on the clear-aperture of 195mm. Additionally, I found a way how to add a quasi-elliptical light-source for the mirrors surface, which is of great advantage for increasing the resolution of the results and to minimize the statistical error. 

Right now, the error for the maximum values is ca. 10% but further decreasing it is no problem because of the mentioned reasons. Maybe, I will make another simulation run on Monday with increased resolution, also because of having better results for my paper.

KAGRA VIS (General)
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AyakaShoda - 19:39, Thursday 01 October 2015 (189)Get code to link to this report
2nd IM almost assembled

2nd IM was almost assembled and shipped to Kamioka together with the 1st IM.

In the 2nd IM, one of the screw was stucked when assembling the side wall (spring side).
I think shorter screw can be inserted, but the long screw cannot be screwed fully now.
Anyway, it works without that screw.

And the heat shrink tube is running out.
So I did not connected the top picomotor cable.

Images attached to this report
189_20151001095303_20150930060927660ios.jpg 189_20151001095317_20150930060946639ios.jpg
KAGRA VIS (OSEM)
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TomotadaAkutsu - 23:29, Wednesday 30 September 2015 (187)Get code to link to this report
Comment to Fixing coil wires to OSEM coil bodies by a vac seal (Click here to view original report: 137)

Plus 5 OSEM coil bodies are washed (by ethanol), and then 67+5 = 72 OSEM coil bodies will be available in the end.