Comment to Compensation of BB!EO3 at 0 deg (Click here to view original report: 3544)

File is being saved here after setting up new voltages

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Coating measurement\BB1-E03\20240417\0 deg\AfterCompensation\Thu, May 2, 2024 12-12-22 PM.txt

Comment to Compensation of BB!EO3 at 0 deg (Click here to view original report: 3544)

The voltages for compensation can be found here:

foldername='C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Coating measurement\BB1-E03\20240417\0 deg\CompensationVoltage'

filename='voltagecompensating_0.02_0.002.txt'

Compensation of BB1EO3 at 0 deg

The Jones matrix of the coating BB1EO3 was measured at 3 position 0,14,62 deg. This matrix alongwith BS was used to combine with the input polarization states to find the optimum voltages for compenstion. The desired voltage afterwards were saved in the format where there were range of other voltages obatined using the first set of voltage as locus to create a square of half edge 20mV with step size 2mV.

The coating was moved to 0 deg.

The voltage file was fed to the labview "Complete Integration-File Choice"

The measurement will be started after stable temperature of LC is attained. (warm up time is ususally 30mins)

The laser will be kept on till next week. So, kindly don't turn it off.

recabling and DDS2 issue

[Logan,Marc,Michael]

We took time to check all electronic connections and are now preparing a summary scheme.

During this activity, we also reconnected the 2 missing GRMC/CCFC cables.

We also replaced the broken CC PLL MON cable that was previously broken.

We could lock SHG in similar condition as before (large HOM) but could not lock GRMC despite relatively reasonable alignment.

THe issue is that DDS2 is not detecting the 500MHz clock signal while it is fine for DDS1 and 3.

We are now sending -20.5dBm clock to DDS2. To be further investigated

Comment to issue with LC pc python (Click here to view original report: 3541)

[Hugo,Logan,Marc]

We resetted the previous spyder environnement.

The unloadable libraries issues was solve by doing the appropriate pip install directly in the spyder console.

All usual python codes are working fine now.

issue with LC pc python

There were issues to properly load python libraries on the pc so I resetted spyder settings to default.

Might be an issue for cv2?

Reconnecting after cable management operation

Logan, Michael

I introduced Logan to the squeezer clean room and mostly introduced FP cavity, FSR mode spectrum and PDH locking in the context of the green path.

I realigned the green mode cleaner/Mach Zender assembly to 92% mode matching. But the GRMC PD is not connected to the Cable Management Box. It's a bit hard to find in the giant mess of cables (seems to be unlabelled) so we will try next time.

Labview modification

The labview "Complete Integration for Camera" was modified to save data properly. The issue now was that the VI was too fast with averging of 1st order and there were same points being repeated in the dataset. Some changes were done as follows:

1. Added clear buffer for the averaging filter which is triggered when the number of iterations of averaging loop equals the averging order.

2. Added timer inside the averaging loop to make it a bit slower depending on what averging order you do. So, for different order you have different speed. Because the data saving was fine with averging order of 10, but was saving same data 4 times for averging order 1.

Comment to Manipulation 2D polarization (Click here to view original report: 3537)

1 LCD à 0° : Thu, Apr 18, 2024 11-14-30 AM.txt
1 LCD à 90° : Wed, Apr 24, 2024 3-40-14 PM.txt
1st 45° 2nd 0° : Wed, Apr 24, 2024 6-57-43 PM

Manipulation 2D polarization

After I've finished colimate my beam in the camera, I changed the orientation of my HWP and QWP to get 90° for the azymuthal angle and 0° for my elipticity.

Then, I made measurement with only 1 LCD of the polarization when we put a video on the LCD (video = all the 256 RGB value).
I did the same with 1 LCD oriented at 90°.

After doing this, I put the two different LCD and adapt my setup in order to get two different video, which allows you to combine the 256*256 different combinations.

All the setups seems to work.

Note : The camera is not synchronized with the 2 video make with a python.

HWP measurement at different positions

Mounted HWP on roator mount and measured the transmission using polcam. The measurement was taken at the following mentioned positions of the rotator mount.

The LC voltage was scanned from 0-3.5V with 0.1V step.

0deg:

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Retarder\HWP\0 deg

Tue, Apr 23, 2024 4-45-43 PM.txt

38 deg:

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Retarder\HWP\38 deg

Tue, Apr 23, 2024 5-10-09 PM.txt

The choice of position of rotator mount is random. The measurement is being taken to check if I can reconstruct rotation using the same method as being used for coating.

Mesurement of QWP at different positions

Mounted QWP on roator mount and measured the transmission using polcam. The measurement was taken at the following mentioned positions of the rotator mount.

The LC voltage was scanned from 0-3.5V with 0.1V step.

0deg:

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Retarder\QWP\0 deg

Tue, Apr 23, 2024 11-43-44 AM.txt

62 deg:

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Retarder\QWP\62 deg

Tue, Apr 23, 2024 11-57-20 AM.txt

Comment to Vacuum Pumping (Click here to view original report: 3529)

The pressure at 8:00 was 4.7*10^-4 Pa. Looking at previous logs, the final pressure is consistent with past values.

I plan to start cooling on Thursday.

I also checked the valves for water supply to compressor are open. So I might not have to worry about cleaning up the water lines. I heard the water is supplied by ATC, but do I need to turn on the water chiller?

Mesurement of coating at different positions

It seems there could be some issue with previous data, as there is some issue with reconstructing rotation of the coating. I took measurement at several position of coating today. The coating BB1EO3 is mounted on a rotator and hence the rotator is rotated at 0 deg, 14deg and 62deg. The voltage scanned was from 0 to 3.5V with 0.1V resolution and averaging of 10th order is implemented.

Also the rotator mount was changed. previoulsy we were using rotator alone and hence it was quite difficult to have finely tuned alignment between the incident and reflected beam. The rotator is now mounted like this and now we could perfectly align the reflected beam with incident beam after the BS

path = "C:/Users/atama/OneDrive/LC-Experiment/Measurement Data/"

0 deg

14 deg

Comment to Vacuum Pumping (Click here to view original report: 3529)

I turned on the TMP at 12:54. The pressure at that time was 3.58*10¹ Pa.

The pressure at 13:05 was 8.1*10^-2 Pa.

I will continue pumping for a while (until Monday).

Note: The TMP is in "local" mode and can only  be operated using the front control panel.

Comment to Rotating coating and measuring at 2 position (Click here to view original report: 3502)

The voltage of 0-3.5V was chosen in contrast to previous choice of 0-5V or 0-25V. It is because most of changes induced in azimuth and ellipticity due to LC is around this range of voltage.

Rotating coating and measuring at 2 position

An old elog that I forgot to post and was in my drafts.

The LC were scanned from 0-3..5V with 0.1V resolution

Measurements were taken at coating position of 0 and 28deg

All the measurement were saved with the the labview where we can even save std on each parameter.

Input_foldername=os.path.join(path, 'Polarization states/20240401')
input_filename= 'Mon, Apr 1, 2024 9-59-08 AM.txt'

for 0 deg
Output_foldername = os.path.join(path, 'Coating measurement/BB1-E03/20240401/0 deg')
output_filename ='Mon, Apr 1, 2024 3-52-42 PM.txt'

for 28 deg
Output_foldername = os.path.join(path, 'Coating measurement/BB1-E03/20240401/28 deg')
 output_filename ='Mon, Apr 1, 2024 9-25-18 AM.txt'

Measurement

I've made 4 different measurements with the single LCD (monitor screen). I measure the elepticity and the azimuthal of the polarization beam after passing throw the LC of the monitor. On the monitor I put a video which gradually changes from black to white.
4 different video for : fast or low video and different power of the initial beam.

Vacuum Pumping

I turned on the scroll pump today for chamber evacuation. I did not notice any issue with the scroll pump operation.

• Turned on Scroll Pump at 8:03
• Opened right angle valve between TMP and scroll pump at 8:08
• Opened gate valve between chamber and TMP at 8:15 (fully open at 8:18)
• Turned on Vacuum guage at 8:23 (The pressure was 3.75*10³ Pa)

Manipulation 2D polarization

After raising the beam with the help of the mirrors at angle, I have characterized the beam obtained with the Beam profiler and a lens f=30mm.
I find z0 = 31cm et w0 = 9.1μm, (z=0 : Corresponds to the characterization lens --> 79,7cm on the meter of the table).
So I found the characteristics of the initial beam : z0 = -9.915m et w0 = 272μm (z=0 still the same).

After that I rebuilt a telescope with two lenses : F= 500mm Bi-Convexe et F=-25,4 Plano-Concave, second one place at 500 mm because the focal seems to be at 525mm...
I put the single pixel Camera at the end, just after the second lens.

Finally, I put the first LCD in front of the large beam just after the mirrors, and I have a control of the monitor, and it seems to work but several remarks :
-There is an important diffraction of the light due to the array of the LCD ---> important power losses
-I remark that we still have color on the LCD, so we don't only have the LC on the screen...
-We need a second computer to put the image on the screen because we have no idea what we put on the screen except when you use two polarizers and a flashlight to see what is on the screen.