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R&D (Cryogenic)
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RishabhBajpai - 13:29, Tuesday 07 November 2023 (3333)Get code to link to this report
Nodal Support
I reassembled part of the nodal support system.
I need to fix the electrostatic actuator that came off during assembly.
Since I could not find epoxy in NAOJ, I will bring it from KEK and finish the assembly once the actuator is fixed.
(We can't upload photos to the logbook. We should discuss how to maintain the logbook)
R&D (Cryogenic)
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RishabhBajpai - 06:43, Tuesday 07 November 2023 (3331)Get code to link to this report
Ultrasonic Wash- Nodal Support System
When: 2023/10/11
(log book went down around this time)
(it seems we cannot upload photos to logbook)

I cleaned the nodal support system components with help from Hirata-san.
During this work, the ethanol from one of the containers was used up.
R&D (Speed meter)
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MunetakeOtsuka - 16:53, Thursday 02 November 2023 (3329)Get code to link to this report
Tabletop experiment of speed meter
2023-11-02 1500-1630 @ ATC North bld.txt, NAOJ
Tabletop experiment of speed meter
Yohei Nishino & Munetake Otsuka

-Configuration
1)Laser -> 2)QWP -> 3)HWP -> 4)Convex lens -> 5)BS -> 6)HWP
-> 7)FR -> 8)Rotary Disc Shutter -> 9)HWP -> 10)AOM -> 11)Mirror
-> 12)Mirror -> 13)Convex lens -> 14)EOM -> 15)Convex lens
-> 16)FR

-Polarization mesurement after 15)Convex lens
Horizontal 27,3 uW with background 4.3uW
Vertical 4.7 uW with background 4.3uW
Without polarizer 32.9 uW with background 4.3 uW


-Beam profile after 15)lens
position x-width y-width
875mm 0.42mm 0.53mm
900mm 0.51mm 0.56mm
925mm 0.58mm 0.63mm
950mm 0.68mm 0.71mm
975mm 0.74mm 0.84mm
1000mm 0.82mm 0.84mm
R&D (Speed meter)
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MunetakeOtsuka - 10:39, Thursday 02 November 2023 (3327)Get code to link to this report
Tabletop experiment of speed meter
2023-10-18 10am-3pm @ ATC North bldg, NAOJ
Yohei Nishino & Munetake Otsuka
-Configuration
1)Laser -> 2)QWP -> 3)HWP -> 4)Convex lens -> 5)BS -> 6)HWP
-Optical power measurement
output of 4) : 473mW
output of 4) ->Polarizer @ 90 deg : 1.8 mW
output of 4) ->Polarizer @ 0 deg : 391 mW
output of 5) : 272 mW
output of 6) : 219 mW
-Optical component specifications
Extinction Ratio of Polarizer : 0.46% (=1.8/391)
Transmittance of 5)BS @ polarized light : 69.6% (=272/301)
-Configuration of wave plate
2)QWP : 24 + 0.4
3)HWP : 144 + 0.5
-Confirm 6) is really HWP @ 1064 nm
-Beam profile
-Firstly, tried to measure the beam profile with 2 ND Filters:-
beam profile has terrible modal noise, so change one ND filter to gradient shutter.
-output of 6) : beam diameter 1.0 mm
-output of 6) -> Faraday Rotator : 0.7mm with some modal noise
R&D (Speed meter)
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MunetakeOtsuka - 10:37, Thursday 02 November 2023 (3328)Get code to link to this report
Tabletop experiment of speed meter
2023-11-01 1130-1630 @ ATC North bld.txt, NAOJ
Tabletop experiment of speed meter
Yohei Nishino & Munetake Otsuka
-Configuration
1)Laser -> 2)QWP -> 3)HWP -> 4)Convex lens -> 5)BS -> 6)HWP
-> 7)FR -> 8)Rotary Disc Shutter -> 9)HWP -> 10)AOM -> 11)Mirror
-> 12)Mirror -> 13)Convex lens -> 14)EOM

-Optical power mesurement of 10)AOM
1st diffraction light 1.06 mW
Transmitted light 0.69 mW
while input light 1.81 mW

-Optical component specifications of 10)AOM
Diffraction efficiency : 60% (=1.06/(1.06+0.69)

-Configuration
9)HWP : 51
Function generator for 10)AOM : 40MHz 5V(0 to peak)

-Beam profile after 13)lens
position x-width y-width
700mm 0.29mm 0.38mm
750mm 0.28mm 0.20mm
800mm 0.33mm 0.34mm
850mm 0.49mm 0.60mm

Birefringence mitigation (General)
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MarcEisenmann - 17:48, Monday 30 October 2023 (3326)Get code to link to this report
rotating HWP

Using data from the long polarization states generation of elog3308 I saved all the voltages required to generate a rotating HWP with 0.1deg error in ellipticity.

The 1st column is V1 and second column V2. They are sorted so that the HWP rotates from -90 to +90 deg.

The file is 'rotatingHWP.csv'

General (General)
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RyutaroTakahashi - 17:25, Tuesday 10 October 2023 (3325)Get code to link to this report
Monitor Cam

I set a monotor camera tentatively in the center room of TAMA at the request of the safety office. If the test operation was reasonable, I would set more cameras at some points.

Images attached to this report
3325_20231010102124_monitorcamera.jpg
R&D (Cryogenic)
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RishabhBajpai - 17:36, Friday 06 October 2023 (3324)Get code to link to this report
Diassembling nodal support setup for cleaning
The nodal support system (fig. 1) was delivered to NAOJ this Monday (10/02).
Today, I disassembled the setup for cleaning.
I did not have the CAD drawing, so I winged the disassembly and only broke the electrostatic actuator.
The components are now on the optical table in plastic bags (fig. 2).
I will clean them and reassemble the setup next week (probably Wednesday).

Images attached to this report
3324_20231006103420_1.jpg 3324_20231006103430_2.jpg
R&D (Roberts Linkage)
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KoheiMitsuhashi - 19:10, Wednesday 20 September 2023 (3323)Get code to link to this report
measured the transfer function of double pendulum made by inverted pendulum and Roberts' Linkage

I made double pendulum made by inverted pendulum and Roberts' Linkage.

So I measured the transfer function from IP actuator power to IP displacement and Roberts' Linkage displacement to check how it is.
Each set up pictures are attached(Fig1, Fig2).
IP displacement are measured by LVDT mounted on IP top stage.
Roberts' Linkage displacement are measured by photo displacement sensor.
Each transfer function are attached(Fig3, Fig4).

From Fig3 gain plot, I can realzed that common mode and differrential mode peak and characteristical dip.
I can also realized that points from Fig3 phase plot.
At 400mHz peak is IP yaw motion, and at 1Hz peak is Roberts' Linkage paw motion.

I mentioned about Fig4 lately.

Images attached to this report
3323_20230920114055_fft1.png 3323_20230920114106_fft2.png 3323_20230920115115_12473124631252212540125311247112519124831248820230920185003.png 3323_20230920115125_12473124631252212540125311247112519124831248820230920185036.png
R&D (Roberts Linkage)
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KoheiMitsuhashi - 16:31, Wednesday 20 September 2023 (3321)Get code to link to this report
suspend Roberts' Linkage and measured it' resonant frequency

We suspend Roberts' Linkage from IP top (image: Fig1, picture: Fig2). The parameters were as follows.

high [m] 0.4
weight [kg] 28.73

I also measured the power spectra with using Photo displacement sensor(Fig3). During measuering, we locked IP physically using meal fitting.
I attached the results (Fig4).
I can realized that there are two peak. These peaks are also from resonant frequency.
I thought it from difference between wire lenghts.

Images attached to this report
3321_20230920092133_12473124631252212540125311247112519124831248820230920162110.png 3321_20230920092927_12473124631252212540125311247112519124831248820230920162848.png 3321_20230920094341_12473124631252212540125311247112519124831248820230920164318.png 3321_20230920094453_powerspectraoflrh1scope.png
General (General)
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RishabhBajpai - 10:32, Wednesday 20 September 2023 (3320)Get code to link to this report
Clean Up (folded cavity optical table)
This morning, I cleaned up the folded cavity optical table.
The optics are in the small desiccator (fig.2), and the pedestals and mounts are in a plastic box (fig.3).
I found some mirrors had scratches on them. In hindsight, I should have marked them. (Anyhow, it can be sorted later by the user.)
I will clean up the surrounding area after moving the optical table.
Images attached to this report
3320_20230920032942_1.jpg 3320_20230920032950_2.jpg 3320_20230920033121_3.jpg
Birefringence mitigation (General)
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ShalikaSingh - 16:08, Thursday 14 September 2023 (3319)Get code to link to this report
Labview modifications

The option to choose a specified configuration from a pre-saved file has been added. As a result you can load the list of LC voltages required for any particular scenario. 

Birefringence mitigation (General)
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ShalikaSingh - 16:06, Thursday 14 September 2023 (3318)Get code to link to this report
BS added to the setup

[Shalika, Gabriella]

The setup was modified and two beam splitters were added (before and after LCs). The measurement to calibrate the beam splitters (both reflection & transmission) were taken as well (done without LCs). 

R&D (Roberts Linkage)
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KoheiMitsuhashi - 01:14, Friday 01 September 2023 (3317)Get code to link to this report
Fitting IP's resonant frequency

What I did:
I fited the resuts of IP's resonant frequency to theoretical value.


The equation used for fitting was atttached.
f is IP's resonant frequency.
k_e is spring constant of IP's flex joint .
k is s anti spring constant.
g is gravity constant.
l is length of IP.
m_0 is mass of IP.
M is weight on IP.

From fitting, m_0 is 1.08 kg, k_e is 131 N/m, l is 2.48 m.
 

The results and fitting picture was as follows.
X-axis is weight on IP top, y-axis is IP's resonant frequency.

Images attached to this report
3317_20230831175947_texclip20230901005920.png 3317_20230831180026_fittingofipsresonatfrequency.png
R&D (Roberts Linkage)
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KoheiMitsuhashi - 00:34, Wednesday 30 August 2023 (3316)Get code to link to this report
diagonalization of IP's matrix

What we did:
We diagonalized the matrix of IP, and checked how much diagonalization was.

The matrix's values form LVDTs to imaginally L-axis and T-axis were as follows.

  L T
H1 +0.20 -0.04
H2 -0.07 -0.12
H3 -0.09 +0.13

The matrix's vakues from L-axis and T-axis to actuators were as follows.

  A1 A2 A3
L -2.20 +2.45 +0.46
T +0.45 +3.21 -2.71

I measured the trasfer function from L,T to L,T respectively.
The pictures was attached.
I concluded it was good at some extend.
 

Images attached to this report
3316_20230829173324_30011206871.png 3316_20230829173332_30011206872.png 3316_20230829173337_30011206873.png 3316_20230829173343_30011206874.png 3316_20230829173349_30011206875.png 3316_20230829173355_30011206876.png 3316_20230829173750_30011206877.png
KAGRA MIR (Polarization)
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MarcEisenmann - 09:33, Thursday 24 August 2023 (3314)Get code to link to this report
Comment to spare ETMY measurement started (Click here to view original report: 3311)

The measurement seems to go fine and is mostly finished.

However, because of the new failure of air conditioning the temperature and humidity increased quite a lot in TAMA.

It's about 30deg in main building and quite more inside clean room.

just for safety I turned off PCI laser.

R&D (Roberts Linkage)
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KoheiMitsuhashi - 21:12, Sunday 20 August 2023 (3312)Get code to link to this report
Summary of Roberts' Linkage tabletop experiment.

Mitushahshi

I summarized the tabletop experiments of Roberts' Linkage.

What I did
The followings are what I did.

  • I measured the resonant frequency of Roberts' Linkage with changing COM.
  • I checked the difference of resonant frequencys between x-axis and y-axis(The definitions of these axes are written on below sentence).

Set up
I attached the picture(Fig1).
The Roberts' Linkage was shaked by coil magnet actuator powered by FFT analyzer.
The displacement of it's was detected by photo sensor.
I measured the transfer function from coil magnet actuator voltage to photo sensor read out voltage.

Measurement results
Firstly I mentioned resonat frequency and COM position. I attached the picture(Fig2).
The results says that the resonant frequency get lower and lower when Roberts' Linkage was tuned at hight COM points.
The gap are there between first mesurement and second measuremt. I thought the reasons are some coupling by different tension on wires and by human error with tuning COM(this is most properly).

Secondary, I mentioned the strange peak. I attached the power spectra density plot.
The peak at 71mHz is the resonant, and harmonic of it also are there(rabeled blue).
On the other hands, the strange peak that it is not reasonable by above mention also are there(label green). 
The paper "F. Garoi et al., Passive vibration isolation using a Roberts Linkage, Rev Sci Instrum 74, 3487-3491(2003)" reported that there are cross coupling.
So I measured the x-axis and y-axis resonat frequency. The definition of x-axis is following on the road of 20m interference site(Fig3).
I attached the results. The red one is x-axis, and the blue one is y-axis.
I realized that these axes have a difference resonat frequencys, and conclued that the strange peak is from y-axis' resonant frequency (cross coupling).

Images attached to this report
3312_20230820134736_fig1.png 3312_20230820134829_2.png 3312_20230820134927_3.png 3312_20230820135004_4.png 3312_20230820135048_5.png 3312_20230820135116_6.png
KAGRA MIR (Polarization)
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MarcEisenmann - 16:37, Thursday 10 August 2023 (3311)Get code to link to this report
spare ETMY measurement started

[Aso, Marc, Michael, Rishabh]

We installed spare ETMY with ears up (ie reversed top/down with respect to KAGRA installation) on the translation stage.

It helped a lot to remove the front top right metal support looking from the laser side for the installation.

After small realignment of the 2 photodetectors I checked the mirror center by trying to find the position where the signals drop to 0 (ie edge of the mirror).

X_center = 393.5 mm and Y_center = 155.5 mm.

Then I started measurement with Spol at the input (HWP = 351.2 deg) with maximum AC and DC dynamic range (1V) to take map over 70 mm radius with 1 mm step.

I'll keep these settings during holydays to avoid saturation.

Comments related to this report
MarcEisenmann - 09:33, Thursday 24 August 2023 (3314)

The measurement seems to go fine and is mostly finished.

However, because of the new failure of air conditioning the temperature and humidity increased quite a lot in TAMA.

It's about 30deg in main building and quite more inside clean room.

just for safety I turned off PCI laser.

KAGRA MIR (Polarization)
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MarcEisenmann - 00:25, Wednesday 09 August 2023 (3310)Get code to link to this report
birefringence measurement preparation

I realigned the beam at normal incidence using the razor blades using input power of 1.59mW.

After realignment, I got angle of incidences of 0.009 deg and 0.0059 deg for vertical and horizontal direction respectively.

I tuned the input HWP and QWP to have input s polarized light by minimizing the p polarization component.

With current configuration, 'DC' corresponds to S pol and 'AC' to P pol.

I took 10mn of data with each polarization to finalized the setup calibration.

I was planning to measure the ILM sample birefringence but could not find suitable holder (30mm diameter ; 15 mm thickness).

We plan to start instead with spare ETMY measurement.

Birefringence mitigation (General)
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MarcEisenmann - 00:21, Wednesday 09 August 2023 (3309)Get code to link to this report
HWP birefringence measurement

I reinstalled the output cross-polarizer and also installed a HWP (WPQ-10640-2M from SigmaKoki) just after LC2.

I am now scanning the LCs voltages with various step to measure birefringence in 'electronic Soleil-Babinet' mode.