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Birefringence mitigation (LC)
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ShalikaSingh - 16:35, Tuesday 21 November 2023 (3355)Get code to link to this report
LC2 fast axis

[Shalika, Marc]

Measurements of LC2 fast-axis angle were done. The data was taken in cross polarizer setting. 

We measured fast-axis at 73.42°±0.52°. The angle is quite deviated from previous measurement which can be accounted due to the partially unscrewed LC. 

The second LC was then set at -45° from its fast axis, i.e 28.42°.

R&D (FilterCavity)
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MichaelPage - 13:41, Tuesday 21 November 2023 (3354)Get code to link to this report
A quick look at the system after a long time inactive

I took a quick look at the laser system. I let it warm up for about half an hour.

As expected even the first component in the line, the SHG, is quite misaligned. There are no clear reflection peaks in the cavity scan. The error signal looks quite distorted too (EPSOUT2). 815 mW of IR made it to the SHG entrance, so there is no problem with the laser system, although it seems a bit misaligned at the entrance. The SHG servo can be "locked" but it only outputs less than 20 uW of green. I should remember next time to compared reflection and transmission to the previous reference values, though they are a bit lower compared to recent measurements of SHG input and green output:
- IR incident (just before dichroic mirror) - 684 mW
- IR reflect (before ND2 on PD) - 87 mW
- Green output (just before green FI) - 237 mW

During Chien-Ming's last visit it was noted that the temperature of the laser casing was very warm. This time the temperature of the laser didn't do anything strange over an hour or so active.

I turned on some of the things that were powered off, including the squeezer related servo racks and the RF amps on the floor. I left off the filter cavity related electronics and green AOM RF driver.

I took a 6 port multiplug with an on/off switch to use for the homodyne power supply - it was from a box next to the tool area (somehow I can't upload images right now).

Birefringence mitigation (LC)
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MarcEisenmann - 11:03, Tuesday 21 November 2023 (3353)Get code to link to this report
LC1 fast-axis

[Marc,Shalika]

We took measurements of LC1 fast-axis angle.

We installed LC1 and measured the power after a cross-polarizer for various rotation angles while varying the LC1 voltage from 0 to 25V.

What is a bit surprising is that the fast-axis direction seems to be more sensitive to applied voltages compared to previous measurement.

This is visible in the figure with all fits. to be uploaded when logbook is able to.

In any case we measured fast-axis at 45.49 +/- 0.69 deg which is compatible with previous estimation.

Birefringence mitigation (LC)
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ShalikaSingh - 22:35, Thursday 16 November 2023 (3350)Get code to link to this report
LC1 fast axis tuning

[Shalika, Marc]

The ellipticity after BS was ~0.31° and we weren't able to tune it to 0° and simultaneously keep azimuth after BS at 0°. The tuning was being done by Polarizer and HWP+QWP before BS. We finally decided to remove the polarizer. The tuning of ellipticity and azimuth after BS was then done using HWP and QWP (before BS) to have 0° in both ellipticity and azimuth of the light after BS, i.e. linearly polarized light was ensured. 

Now, we had to recheck if our LC's fast axis was in the required position. (The misalignments could have risen from various factors especially, months of non operational temperature control in tama and not using the system)

The final position of LC would be updated in upcoming elogs.

R&D (Cryogenic)
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RishabhBajpai - 17:23, Thursday 16 November 2023 (3351)Get code to link to this report
ATC Cryostat Cabling

I confirmed the wiring of the ATC cryostat on the vacuum and air side. There are 3 Brundy 48-pin ports at the bottom of the cryostat labelled A, B and C. I only checked B, but the terminology and cabling should (hopefully) be the same for the other 2. The cables in air and vacuum are bundeled in sets of 4 labelled B1- B12. The table below shows the pin layout.

 

Name

(wire bundle)

Pins

Wire Order (Pin number to wire color)
In Air Vacuum
B1 A B C D Red
Red-Black
White
White-Black
Red
Black
Blue
Yellow

(I only checked B1 and B2 but it should be same for the rest)
B2 E F G H
B3 J K L M
B4 N P R S
B5 T U V W
B6 X Y Z a
B7 b c d e
B8 f g h i
B9 j k m n
B10 p q r s
B11 t u v w
B12 x y z aa
Birefringence mitigation (LC)
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ShalikaSingh - 19:04, Wednesday 15 November 2023 (3349)Get code to link to this report
BS cal uncertainty
As mentioned in elog 3345, our BS is mounted on a magnetic mount. Therefore to calibrate both faces, I had rotated the mount. Hence, to check the stability of mount and the uncertainty in our calibration due to this rotation, I calibrated both front and back face 3 additional times. The camera was moved everytime I was measuring reflection or transmission. Hence, there can be few discrepancies from camera position. (the camera was only unscrewed and relocated without changing its mount)
 
As a result, the parameters mentioned in the table show that the magnetic mount is quite stable and doesn't affect(a lot) calibration of either the front or back face.  In all the following cases, the beam was always along same path. Additionally, the average order in labview was 10 during data acquisition.
 

 

Front Face

Back Face

Parameters

Position 1 (3345)

   Position 2         

Position 3

Position 4        

Position 1 (3345)

Postition 2         

Position 3             

Position 4

Reflection (%)

56.5 ± 1.1

56.6 ± 1.7

56.5 ± 1.3

52.8 ± 1.4

47.7 ± 0.8

49.5 ± 1.7

52.6 ± 0.9

49.1 ± 1.3

Transmission (%) 

40.8 ± 0.7

40.8 ± 1.5

40.8 ± 0.8              

40.9 ± 1.7

40.7 ± 0.7

40.9 ± 1.1

40.8 ± 0.7

40.9 ± 1.3

Loss (%)

2.7 ±  1.7

2.7 ± 2.8

2.7 ± 1.9

6.2 ± 2.6

 11.6 ± 1.5

9.6 ± 2.5

6.6 ± 1.6

9.9 ± 2.3

Input Azimuth  (°)

 -0.014+/-0.009

-0.0190 ± 0.0017

-0.0316 ± 0.0017

0.0207 ± 0.0021

1.6018 ± 0.0023

0.0190 ± 0.0017

-0.0316 ± 0.0017

0.0207 ± 0.0021

Reflected Azimuth  (°)

1.4154 ±  0.0022

1.3606 ± 0.0019

1.1625 ± 0.0022

1.5322 ± 0.0023

-0.014+/-0.009

1.4733 ± 0.0017

1.2267 ± 0.0017

1.7301 ± 0.0020

Transmitted Azimuth  (°)

-0.060 ±  0.0027

-0.0654 ± 0.0028

-0.0775 ± 0.0017

-0.0226 ± 0.0017

-0.0939 ± 0.0020

-0.1036 ± 0.0018

-0.0658 ± 0.0021

-0.0360 ± 0.0019

Input Ellipticity  (°)

0.008+/-0.008

0.0178 ± 0.0013

0.0150 ± 0.0013

0.0133 ± 0.0019

0.008+/-0.008

0.0178 ± 0.0013

0.0150 ± 0.0013

0.0133 ± 0.0019

Reflected Azimuth Ellipticity(°)

-0.3969 ± -0.3969

-0.3626 ± 0.0015

-0.3650 ± 0.0025

-0.1964 ± 0.0019

 -0.1469 ± 0.0026

-0.1577 ± 0.0017

-0.0142 ± 0.0018

-0.0392 ± 0.0020

Transmitted ellipticity  (°)

0.2928 ±  0.0028

0.2921 ± 0.0033

0.2977 ± 0.0032

0.3175 ± 0.0016

-0.0549 ± 0.0021

-0.0623 ± 0.0014

-0.0602 ± 0.0014

-0.0555 ± 0.0017

 

P.S

1. Front face = where laser is incident on BS in an ideal configuration, and back face means the face opposite to front face.


2. the folders are saved on pc with the corresponding position name as folder name in BS calibration. 

R&D (Cryogenic)
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RishabhBajpai - 13:28, Tuesday 14 November 2023 (3344)Get code to link to this report
Fixing Electrostatic atuator
The electrostatic actuator dislodged during transportation and came off while disassembling the setup.
Yesterday, I fixed it with Epoxy.
I couldn't remove the old Epoxy (not sure what type), so I just bonded on top of it.
The curing time is 7-14 days, but it should be ready to move by tomorrow.
Birefringence mitigation (LC)
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ShalikaSingh - 12:10, Tuesday 14 November 2023 (3345)Get code to link to this report
BS cal (front and back face)

[13/11/2023]

Due to the position of clamp there was trouble calibrating the back face of BS(from 3342). The mount was changed. Previously we had mounted two different BS on two different mounts. So, in brief this is the second BS.

The BS is mounted on a magnetic mount, so just the upper half of mount was rotated such that the actual position of beam on BS doesn't change. This was best suited to calibrate both front and back face of BS. Even though the BS was rotated to calibrate two faces, the path of transmission and reflection doesn't change. The parameters obtained are as follows:

Input azimuth: -0.014+/-0.009
Input ellipticity: 0.008+/-0.008
 

Parameters Front face (center) Back Face (Center)
Reflection (%) 56.5 ± 1.1  47.7 ± 0.8
Transmission (%) 40.8 ± 0.7  40.7 ± 0.7
Loss (%) 2.7 ±  1.7  11.6 ± 1.5
Reflected Azimuth (°) 1.4154 ±  0.0022   1.6018 ± 0.0023
Transmitted Azimuth (°) -0.060 ±  0.0027  -0.0939 ± 0.0020
Reflected ellitpticity (°) -0.3969 ± -0.3969  -0.1469 ± 0.0026
Transmittted ellipticity(°) 0.2928 ±  0.0028  -0.0549 ± 0.0021
5.0 ±  1.1
5.0 ±  1.1

 

41.02 ± 0.33
Birefringence mitigation (LC)
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ShalikaSingh - 12:06, Monday 13 November 2023 (3342)Get code to link to this report
Beam Splitter calibration (front face)

[10/11/2023]


The front face of BS was calibrated and the properties obtained were:

1. Power
Reflection: (55.5 ± 0.7) %
Transmission: (42.8 ± 0.5)% 
Loss: (1.8 ± 1.2)% 
 
2. Azimuth
Input: 0.0119°± 0.0029°
Reflected: 1.7803° ± 0.0032°
Transmitted: 0.0000° ± 0.0032°
 
3. Ellipticity
Input: 0.0076° ± 0.0027°
Reflected: -0.2128° ± 0.0031°
Transmitted: 0.072° ± 0.004°
Reflection % 55.5+/-0.7
Transmission % 42.8+/-0.5
Loss % 1.8+/-1.2
Input azimuth 0.0119+/-0.0029
Reflected azimuth 1.7803+/-0.0032
Transmitted azimuth 0.0000+/-0.0032
Input ellipticity 0.0076+/-0.0027
Reflected ellipticity -0.2128+/-0.0031
Transmitted ellipticity 0.072+/-0.004
General (General)
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MarcEisenmann - 12:04, Monday 13 November 2023 (3341)Get code to link to this report
Comment to Electrical shutdown preparation (Click here to view original report: 3340)

Takahashi-san, Sato-san and Hirata-san recovered vacuum without issue.

I recovered LC, PCI and Filter Cavity mostly without issues.

However, the wifi antenna in TAMA storage seems to be broken.

Also, one of the power supply switch in FC clean room  (mainly used for homodyne power) is making a strange sound if I turn it on.

I will replace it

General (General)
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MarcEisenmann - 20:03, Friday 10 November 2023 (3340)Get code to link to this report
Electrical shutdown preparation

[Marc, Shalika]

Workstation in room 216/217 off

ATC clean room koach filter off

LC : everything's off

PCI : everything should be off. We could not reach the switch of HEPA filter of pre clean room so it is unplugged (accessible from the stairs)

FDS : everything should be off both inside clean room, all oplevs, coil drivers, DGS. End electronics also off. Vacuum was taken care of by Takahashi-san (?)

Also turned off the server/network switch in storage, the new DGS switch, DAC/ADC and network switch

 

Can not upload pictures but I took the reference levels of several components.

Comments related to this report
MarcEisenmann - 12:04, Monday 13 November 2023 (3341)

Takahashi-san, Sato-san and Hirata-san recovered vacuum without issue.

I recovered LC, PCI and Filter Cavity mostly without issues.

However, the wifi antenna in TAMA storage seems to be broken.

Also, one of the power supply switch in FC clean room  (mainly used for homodyne power) is making a strange sound if I turn it on.

I will replace it

Birefringence mitigation (LC)
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ShalikaSingh - 20:06, Thursday 09 November 2023 (3339)Get code to link to this report
Realigning input beam

[Shalika, Marc]

The recent temperature fluctuations led to multiples changes in beam path(tilted), height and input polarization. The mirrors were tuned to make the beam follow one line and at a uniform height of 75 mm all along the table.

The HWP and QWP were tuned to input a polarization of 0°±0.01°(azimuth) and 0°±0.01°(ellipticity)

The input polarizer was then tuned to get 0°±0.02°(azimuth) and 0°±0.02°(ellipticity). The power after the polarizer was 0.832 mW.

KAGRA MIR (General)
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MarcEisenmann - 14:22, Thursday 09 November 2023 (3337)Get code to link to this report
removal of spare ETMY

[Aso, Marc, Rishabh]

We removed the spare ETMY and put it inside its container.

To do it safely we first removed a front supporting pillar that has to be reinstalled.

Maybe because of that, it was first not possible to move the translation stage upwards (the right motor while looking from the input side was not moving).

After some up/down motion it could move slowly without issue.

We could not find the 3 screws to fix the container lid. We  plan to manufacture new ones.

General (General)
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RishabhBajpai - 10:11, Thursday 09 November 2023 (3336)Get code to link to this report
ATC Optical Table


After discussing with Akutsu-san, I disassembled the Al frame on the optical table in front of the AC unit.


The optics (Nikon camera, some beamsplitters and other items) on the other end of the optical table (away from the AC unit) are still there since I have to discuss what to do with them with someone (who?).


Please feel free to use this table.


Birefringence mitigation (LC)
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ShalikaSingh - 10:47, Wednesday 08 November 2023 (3335)Get code to link to this report
Data acquisition updated

In labview, we now have average filtering implemented. So, we can average camera and power meter's data (using average order from 1-10) at the same voltage of LC. 

Also, as a modification of 3319, we can now do several iterations of the same file and even fix the resolution of data that should be used from the file. 

R&D (Cryogenic)
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RishabhBajpai - 09:32, Wednesday 08 November 2023 (3334)Get code to link to this report
Cryostat Work

I removed the FP cavity from the cryostat in ATC in prepration for cabling work.

The folded cavity optical table is now very crowded (being used by Mitsuhashi-kun and myself).

I want to remove the aluminium frame and foil from the optical table in front of the air-conditioning unit. Is it acceptable?

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