NAOJ GW Elog Logbook 3.2
Regarding the Doughnut Baffle, the two promising candidates for a very good absorption/scattering coating have been tested for their ultra-high vacuum compatibility.
The results show that VB has better UHV capabilities then MV. Especially water seems to be highly abundant on the surface of MV.
May 26
Checking condition of the clean booth at 1530-17:00 by Takahashi.
1) Turned on all (16) filters. 4 filters had been working before.
2) Hirose-san measured particles by the large counter. I measured particles by the small counter too. Number of particles was 5/L just after turnung on the filters. Humidity was 80.5%.
3) Hirose-san measured particles continuously during I walk around.
May 27
Replacement of the breadboard (1).
1) Cleaned the floor of the clean booth by the vacuum cleaner and the mope.
2) Opened the chamber.
3) Moved the optical bench into the clean boooth by the jib crane.
4) Extracted the suspension from the chamber and put it on the optical bench.
5) Extracted the breadboard. Up-down movement of the crane (chain block) is very slow.
6) Rapped the breadboard.
May 28
Replacement of the breadboard (2)
1) Cleaned the floor of the clean booth by the mope.
2) Cleaned inside the chamber by the vacuum cleaner, the wet wiper, and the dry cloth.
3) The SUS blocks were stacked after first disassembling. Since the guid rods are inside the MCF chamber, we don't use them. The crane can not move to ransverse direction. This is a problem.
4) Unpacked the renewaled breadboard and installed it into the chamber.
5) The breadboard extracted was enclosed by the wood box.
6) Rapped the suspension with decicant.
7) Closed the chamber.
Now a prototype of the oplev receiver
http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3562
is well assembled. Note that the QPD circuit in the photograph below has a wrong connector, and should be modified soon.
27th-28th May,
Takahashi-san, Mark-san, Ishizaki-san, and Ohishi changed MCE breadboard.
Due to the unexpected stack cleaning work, surface level adjustment of the MCE board was postponed to 11th-12th Jun.
Inside the cleanbooth, humidity was - 80% but cleanness was good -ISO class 4.
Optical bench was carried into the booth.
Attached pictures were taken by Koichiro (an Olympus camera equipped to NAOJ Kamioka branch).
[SURFACE SAMPLE]
Newport FRQ-ND02
Absorption 22.2% at 1064 nm
pump power damage threshold 40mW
------------------------------------------------------------------------------------------------------------------------------------------------
Type UV Fused Silica Metallic ND Filter ---> Inconel coated fused silica substrate
Optical Density 0.2 at 633 nm
Diameter 1.0 in. (25.4 mm)
Thickness 0.118 in. ( 3.0 mm)
Material UV grade fused silica
Surface Quality 60-40 scratch-dig
Surface Flatness less than 1 lambda at 632.8 nm over the clear aperture
Wedge less than 3 arc min
Wavelength Range 350 - 2000 nm
Diameter Tolerance ±0.25 mm
Thickness Tolerance ±0.25 mm
Clear Aperture central 80% of dimensions
Damage Threshold 30 W/cm2 CW, typical;
not recommended for pulsed laser use
Angle of Incidence 0 degree
Transmission 63.1 % at 632.8 nm
Optical Density Tolerance ±7%
Chamfers 0.25-0.76 mm face width
Chamfers Angle/Tolerance 45 ±15 degree
Cleaning Non-abrasive method, acetone or isopropyl alcohol on lens tissue recommended
[BULK SAMPLE]
Schott glass NG-12
Thickness 3.6 mm
Absorption rate 116% /cm
Refractive index 1.48 at 1014 nm
Pump power damage threshold 100 mW
--------------------------------------------------------------------------------------------------------
Absorption = 1.16 /cm * 0.36 cm = 0.418 = 41.8%
Dummy flag and (prototype) flag base were delvered as attached file.
By using these parts I will try to adhere.
Hotplate AsOne ND-1
Radiation thermometer Fluke 62 MAX+
After the delivery, I made operation tests as an attached file.
See (in Japanese)
http://gwclio.icrr.u-tokyo.ac.jp/lcgtsubgroup/inoutoptics/2015/05/category-a-viewport-window-2.html
I made course alignment of the pump beam as shown in the attached file.
Then at final end of the laser I checked the laser power fluctuation.
Within a hour there is no obvious drift.
I wll make calibration test.
I summarized this below;
http://gwclio.icrr.u-tokyo.ac.jp/lcgtsubgroup/vibrationisolation/2015/05/installation-of-finshig-rod-to-kagra-bottom-filter.html
The current status of the flexi circuits for OSEMs are here:
http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3570
Mechanically it appears nice, but no holes for soldering... I'm waiting for the alternatives.
The next step would be measuring the outgassing rate at KEK.
I've seen light proflies of LED candidates for OSEM: OP232 and TSTS7100, and found the latter is better in terms of the uniformity, which would be important parameter for OSEM.
Each LED is set in the LED holder of an OSEM, and I did the check above w/ and w/o the additional lens, which was said to help collimation of light; it looks helping situation somewhat.
When test benches are prepared, I can test them as OSEMs.
Measurement of the laser power stability for optical absorption system.
I found the stability is less than 1% in a hour.
I have written a program to overcome the problems with the Flanagan-Thorne procedure for transfer functions having very strong resonances by using time series of seismic noise.
Still, the results are not as sufficient as without these resonances but better than the procedure from Flanagan and Thorne. I uploaded a graph.
In order to consider the effects of birefringence or double refraction in a uniaxial crystal like sapphire or calcite, I personally wrote a document
http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3519
to follow the discussions in CQG 27 185015 (2010).
In short:
(1) The KAGRA ETM with 0.05-degree wedge at its AR side would not spilt optical beams due to birefringence or such splitting is ignorable even if the c-axis of the sapphire substrate is tilted in no more than 2 degrees to the HR surface; the effect is indeed small, as the difference between ordinary and extraordinary index of refractions of sapphire are small.
(2) I found the CQG paper mentioned above contained at least two typos in its eq. (7), as indicated in my document.
Be careful that I don't mention any effects from polarization mixture. A uniaxial crystal would be used as a wave plate, and that means, it will mix two electric-field vectors in a propagating light beam through the crystal if its c-axis is tilted. The phase modulation in the light could be converted to amplitude modulation and vise versa due to the effects...
Member: Takahashi, Ohishi, Ishizaki, Barton, Doi
[April 23 AM]
- Measured particles (4-10/L@1F, 29/L@2F).
- Removed lapping for the chamber.
- Wiped the floors by a mop.
- Wiped the chamber by wet cloth.
- Measured particles (2-4/L@1F, 11/L@2F)
Member: Takahashi, Ohishi, Ishizaki, Barton
[April 21 AM]
- Checked the status around the MCE chamber.
- Found the alert for oxygen (19.0%).
- Went out of the tunnel.
- Calibrated the sensor.
- Reentered to the tunnel to measure the oxygen density (20.5-20.7%).
[April 21 PM]
- Cover the sheet over the clean booth to avoid drop water.
- Lapped the MCE chamber.
[April 22 AM]
- Wiped the roof of the 2nd floor in the clean booth.
- Wash the 2nd floor by city water using a water gun.
- Dried out the 2nd floor by wiping.
[April 22 PM]
- Wash the 1st floor by city water using the water gun.
- Wiped the roof of the 1st floor.
- Wash the 2nd floor by pure water using the other water gun.
- Wash the 1st floor by pure water using the water gun.
- Dried out the 2nd floor by wiping.
- Dried out the sheet by wiping.
- Measured particles (64900-77800/L@1F, 122200/L@2F)
- Turn on the fan of filters.
Torii-san made another measurement on VB with his improved setup. So I calculated the BRDF according to his result.
I also did a first "real" measurement with the JASMINE scatterometer on a SB plate. I put the results in the attachment.
I was asked by the JASMINE people to tell them how to use the scatterometer. Maybe in the next time I will have to teach it to some of their students.
I upload three drawings.
As Akutsu-san pointed me to this, I should add that the strange curve of PRM(horizontal) is maybe due to the high peak of its transfered vibration noise at around 0.5Hz.
It seems that I first have to dump this peak to become a more realistic result...