Manipulation on the 2 AOM set up

I made the design of the set-up, I will use 4 different lenses to pass in the AOM probably, f=-50mm f=50mm f=-100mm f=200mm.


I removed the lens f=100mm and start to install the f=-50mm and f=50mm(not labeled yet) 10cm after the HWP.

optimization of jones matrix

put the condition on jones vector such that matrix is computed only for 2 orthogonal set of jones vector. 

so the dot product is supposed to be 0. I have kept the range to be 85-90 deg. Therefore the dot product is required to be less than 0.2

New manipulation AOM

I use the begining of the set-up of the LCD and after the QWP and the HWP I put a lens f=100mm, and I characterize the beam.

Before the lens, w0 = -47,1 mm ; z0 = 26 μm , after the lens : w0 = 88.8 mm ; z0 = 49.2 μm

I moved the lens f=100mm after the characterization at d = 0.2 m (d = 0 is the same has the previous characterization)

!!!! The zero of reference did not correspond to any optic know, but it's at 101,5cm on the ruler, or the third a hole after the HWP.

DDS2 issues investigation

[Logan, Marc]

Following the reinstallation of the mixers box we could not lock the GRMC.

We found out  it was because the DDS2 was not generating any sidebands but was just outputing some low amplitude broadband noise.

We could see that this issue was somehow related to the 500MHz clock as the software could not recognize it from time to time.

Today we checked the DDS2.

All voltages supply are correct.

All output (filtered or not) are just noise increase.

Then we checked the 500 MHz clock output and got

Channel 1 : -8.6dBm

Channel 2 : -16.7dBm

Channel 3 : -19dBm

Channel 4 : -21 dBm

We checked the output of Wenzel output and got -8dBm.

It seems there are some issues with the splitter (ZFRSC-4-842-S+) that creates the low clock power.

We swapped the clock of DDS2 to channel 1 and got the expected output powers.

We'll check if the remaining amplifier can be used for this clock output or if we have to purchase a new splitter.

Comment to OPO replacement ATC beam setup (Click here to view original report: 3556)

Because the beam profile was normal, I put back the QWP and the HWP and verified if it was s-polarized yesterday. Today, I put the new Faraday Isolator and adjusted it. I measured the intensity without the FI at around 30mW and with at around 27mW. That gives a transmission about 90% and the manufacturer gives 91% of transmission. But because I had trouble adjusting it, I'll do a beam profile tomorrow to check the new FI and the setup.

Comment to OPO replacement ATC beam setup (Click here to view original report: 3556)

Yesterday I prepared a new beam path to measure the beam profile directly from the laser. Today I measured the beam profile and at first it looks normal. So as we thought, the problem seems to be with the Faraday Isolator. I need to finish making the beam profile with all measurements to be sure of that but for now, it looks normal (at least with the W profile values).

Comment to OPO replacement ATC beam setup (Click here to view original report: 3556)

We took a Thorlabs IO-5-1064-HP from a box of miscalleneous optics for KAGRA filter cavity testing (next to Mitsuhashi Roberts linkage experiment, purchased end of FY23).

We put it on a micro tilt adjustment stage and made sure it could be adjusted to the beam height from the Mephisto (72-73 mm). Actually the Faraday isolator that was already there was just put on a pedestal post instead of an adjustment stage, so it is likely that the vertical alignment through the FI was not good, generating a visible higher order mode and causing the improper beam profile.

OPO replacement ATC beam setup

Logan, Michael

We once again found that the beam profile is showing some strange behavior with the asymmetry of the beam divergence. By using the profiler camera we see that it is probably due to misalignment of the Faraday isolator.

Comment to Compensation of BB1EO3 at 0 deg (Click here to view original report: 3544)

Did scans from

LC1, LC1step, LC2, LC2Step, averaging

0-25V, 0.2V, 0-25V, 0.2V

then observed and put a constraint on ell and azi of 2 deg

second scan 

0-1V, 0.01V, 0-25V, 0.1V

15-25V, 0.1V, 0-25V, 0.1V

third scan

0-0.06V, 0.01V, 0-8V, 0.05V

15-25V, 0.01V, 0-5.2V, 0.01V

15-25V, 0.01V, 5.2-8V, 0.05V

0-0.06V, 0.01V, 0-4.3V, 0.01V

4th scan

0-0.04V, 0.005V, 0.83-1.2V, 0.001V

15-25V, 0.005V, 0.83-1.2V, 0.001V

5th scan

14.99-15.02, 0.001, 0-2V, 0.001V

24-25V, 0.001V, 0.95-0.994V, 0.001V

Comment to Compensation of BB1EO3 at 0 deg (Click here to view original report: 3544)

Even though the voltages are being used from the file, it seems there could be a deviation, considering we did the calibration of LC 2 months ago. I can't see a zero crossing in azi and ell, also the file is a bit huge, so it will take longer than expected.

I am going to instead do scan using the voltage range estimated but without using the file, and doing first a rough scan, and then will later do a finer scan.

The voltage range estimated from characterization is 7-8 V for LC 1 and 0-25V for LC2 with condition of 2 degrees on azi and ell. 

So, doing a scan from 6-9V with 0.2V step, and 0-25V, 0,2V step. 

measurement file:

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Coating measurement\BB1-E03\20240417\0 deg\AfterCompensation\Sun, May 5, 2024 2-44-03 PM.txt

(could see zero crossing in labview, still need to plot, measurement finished by the time I finished writing this elog)

Comment to Compensation of BB1EO3 at 0 deg (Click here to view original report: 3544)

Couldn't transfer voltage file , a bit too huge

decreased condition to 20mV, 2mV and 2 degrees.

Also, I had made a mistake in conversion from rad to degree in the previous one , at one instance

voltage file:

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Coating measurement\BB1-E03\20240417\0 deg\CompensationVoltage\voltagecompensating_0.02_0.002_2.txt

measurement file :

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Coating measurement\BB1-E03\20240417\0 deg\AfterCompensation\Sat, May 4, 2024 6-05-39 PM.txt

Comment to Compensation of BB1EO3 at 0 deg (Click here to view original report: 3544)

The measurement stopped because of windows update. I have paused windows update for next 5 weeks.

Started another one with new voltage set of radius 50mV, step 5mV. The condition on ell and azi was 5 degrees.The measurment is being saved with 1 average.

voltage file is here:

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Coating measurement\BB1-E03\20240417\0 deg\CompensationVoltage\voltagecompensating_0.05_0.005.txt

find the measurment file here:

C:\Users\atama\OneDrive\LC-Experiment\Measurement Data\Coating measurement\BB1-E03\20240417\0 deg\AfterCompensation\Sat, May 4, 2024 5-10-32 PM.txt

Comment to ATC OPO input PZT replacement - beam profile characterization (Click here to view original report: 3547)

We tried to calculate the beam profile but it seems that the beam divergence going in does not match the beam divergence going out.

i.e. approaching the beam waist, the beam shrinks ~ 100 um diameter per screw hole, but going past, it increases only ~ 50 um per screw hole.

We will look again for the source of this odd behaviour.

ATC OPO input PZT replacement - beam profile characterization

Logan, Michael

I showed Logan the use of the ATC clean room and the experiment setups we have there.

I showed and supervised the use of the Coherent Beam Master BM-3 UV beam profiler. Although I dropped and broke the included NG9 ND filter (0.5% transmission). The manual says to use below 5 mW and 200 W/mm^2 without the filter so it's fine in this case (3.8 mW).

We measured the beam profile from the s-polarized beam split off in the Taiwan/Korea experiment setups. I thought this beam was to be collimated at 2.3mm over some distance, but it doesn't maintain that size for long and turns out to have a waist of ~ 200 um radius about 30-40in from the PBS. So I also question a bit the Taiwan fiber SHG beam size, but we can look at that later. I tasked Logan with fitting the beam shape and redetermining the mode matching elements for the OPO.

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?