Today with Matteo we removed AZTEC #1 and repeated bulk calibration (R = 0.5769 cm/W) which is compatible with before.

Then, I installed a steering mirror to make the pump beam goes to the birefringence imaging unit.

Using the 2 razors blades I measured the beam position on the last steering mirror of the injection unit.

Then I move the razor blade as far as possible in z and place it in either horizontal or vertical where the beam is located on the last steering mirror.

Note that during the horizontal position tuning it is important to make sure that the beam is still aligned into the power-meter.

I then tuned both horizontal (fig 1) and vertical (fig 2) to reach angles of incidence of 0.014 and 0.006 deg respectively.

This is more than a factor 30 below the KAGRA precision requirement on the c-axis orientation so it is fine.

I connected s polarization to AC and p polarization to DC. (ie old lockin amplifier).

I reduced the laser power to about 359 uW so that we have at maximum about 1V on the lockin amplifier.

I tuned QWP and HWP (0.1 deg precision) to inject linear polarization :

hwp = 336.2 deg (s pol)
AC_min = 355/1e6
DC_max = 9.86*1/10

hwp = 21.2 deg (p pol)
AC_max = 746000/1e6
DC_min = 2.98*0.1/10

The PSD is far from saturating so maybe we could increase a bit the pump laser power and add attenuators before the lockin amplifier.

We had some concerns with previous calibration of AZTEC #1 absorption measurements so we repeated the measurements.

With R = 0.5648 cm/W we have about 60 ppm/cm absorption which is compatible with previous estimation.

Abe, Marc

First we realigned the setup and tuned both HWP and QWP to inject s polarization.

With ceiling lights off we got :

hwp = 5.5 deg seems pure s
s = 915mV
p = 9.98 mV
hwp = 320.5 deg
s = 22.2 mV 
p = 805 mV

We installed the Soleil-Babinet compensator and tried to align it with auto-collimation.

However, while acting on the yaw steering screw, the retaining spring jumped outside the mount (even if we didn't felt any resistance or didn't reach the end of the screw range...)

Matteo helped us to reinstall it using the ones of an old mirror mount.

Once it was fixed, we could align the SBC without issue.

Tuning the SBC to reach maximal s polarization at the readout we measured :

s = 20.4 mV
p = 652 mV

We can not reach as pure s polarization as before ...

Next step is to use the detent stop by 45 deg and use the Vernier screw to reach again pure s polarization, press the zero of this Vernier, move it again so to reach the next s polarization.

We measured d  = 13.365 mm and got :

s = 21 mV
p = 673 mV

d is our calibration parameters and we can now use it to start measurements.

The beatnote can be seen with lower reference level (10dBm) as shown in the attached picture.

[Takahashi, Aritomi, Marc]

Since the BS pitch/yaw picomotors didn't move, we opened the BS chamber and checked BS suspension. All magnets are fine, but BS was touching the earthquake stopper so Takahashi-san adjusted the BS suspension. 

However, BS pitch/yaw picomotors still don't move. We can hear the sound of picomotor, but the sound is smaller than usual. We also checked BS X/Y/Z picomotors. BS X/Z picomotors moved with usual large sound, but BS Y picomotor did not move without any sound.

To check if the problem is due to the picomotor itself or not, we disconnected the wire for BS yaw picomotor and connected it with a spare in-vac picomotor. The spare in-vac picomotor can be moved so the problem should be the picomotor itself. We have not checked the BS pitch picomotor, but we guess the problem would be the same. Since we have only one spare in-vac picomotor in TAMA, Takahashi-san will bring some spare in-vac picomotors from KAGRA and replace them next next Monday. 

I couldn't find the p-pol laser and sidebands on the spectrum analyser (figure 1). I made sure the DDS board was reset properly, the lasers had proper current and temperature, and the beam was going into the fiber. I also tried disconnecting and reconnecting p-pol cables that I could see. Maybe something is disconnected elsewhere?

CC seems ok (figure 2)

I changed the root password back to normal. For me it was just Linux paranoia to make the root password different but I guess it doesn't matter here.

Today I moved the clean booth that was in the storage room on the test setup for the Soleil-Babinet.

Indeed we want to install it later on the PCI setup and want to limit possible dust contamination.

All the optics that were below (seems to be TAMA mirrors) and screws, magnets, etc... are now inside the clean booth of the microscope.

The setup is now ready for calibration of the Soleil-Babinet and we plan to use pure s-polarization for this.

Marc Michael

Today we brought 2 SR560 to input oplev (one from the OPO test setup, one from the elec shop).

We reinstalled the shift PSD and a steering mirror on the rail and centered the PSD.

Note that the tilt PSD and its steering mirror are really close to the rail so the newly installed one have barely enough room to move.

Marc, Matteo, Michael

One possible reason for our very low coherence could be that we injected uniform noise with 4000 counts.

To improve both the driving and sensing it is actually better to inject noise through swept sine.

We did so with noise amplitude of 10000 counts and found that the length mechanical resonance at 0.9 Hz was strongly excited in every dof.

Either the noise is too strong, the PSD is at a wrong position or the driving matrix needs to be tweaked.

We are currently taking again this measurement with lower noise amplitude at 4000 counts.

Marc, Michael

We checked the END oplev SR560 and found out that the length oplev one was saturating.

We decreased the gain of all down to 1 and realigned all signals. After that we increased the gain back to 100.

For reference, the tilt PSD sum is about 4500 counts and shift PSD sum is about 3000 counts.

Marc, Michael

Because we are missing some SR560 now to check the input oplev we decided to check the end ones.

We recentered the beam on the PSD and confirmed the good condition by measuring the usual spectrum of the END oplev for pitch and yaw.

We tried to measure the TF between END mirror yaw excitation end the 3 dofs of the oplev.

However, we did not manage to have coherence about 0.1 between yaw excitation and yaw signal from the oplev.

We checked the coils and they are working fine.

We injected white noise from about 500 to 4000 counts amplitude but it did not change the coherence value.

We will try to check with excitation over longer duration.

We also tried to realign the length PSD but could not find proper values from MEDM.

We will try again this alignment removing the SR560 to avoid too large gain of the signal.

This entry reports absorption measurement of AZTEC #3 with R = 0.5793 cm/W and about 7.7 W of incident pump power.

Its absorption is in agreement with KAGRA requirements.

Recently, the C disk is almost full due to large size of windows folder.

This paused several times on-going measurements.

We will try to update windows (maybe to version 11), to see if it solves the issue.

In the meantime, I changed the default folder where the map data are saved to D:\PCI_measurements.

Marc, Michael, Yuhang (remote)

It was reported in elog 2828 that input oplev spectra are similar for pitch and yaw.

First we wanted to realign input oplev but found out that diaggui was timed out.

This can be fixed by restarting the standalone pc.

Before that, we need to take a snapshot of the medm configuration but the disk was almost full (99%). In the past, this prevented proper snapshot (eg in elog 2881) so we deleted the data from the disk beforehand.

We followed procedure from elog 1979 where the delete command is rm -r 13*** to delete all files starting with 13. We removed all trend/second and full data of May that freed 7% of storage.

After that we could investigate the input oplev behavior.

We found out that there is now only one SR560 (the other one is in ATC cleanroom for the new OPO test setup).

In that case, only pitch is increased by a factor of 100 and we guess that the yaw signal is somehow normalized by the sum (effectively pitch) making the 2 signals identical.

When removing the SR560 connection, we could see the expected mechanical resonances of pitch and yaw.

Note that now x is yaw and y is pitch.

Because we will not replace the OPO so soon, we plan to take back the SR560 from ATC to the input oplev.

Marc and Michael

The frontend PC was reinstalled with Debian 11 - we are going to go with the latest software and hardware that will be used in O5 rather than current versions. The frontend was altered with the following manual partition setup (figure 1):
/boot - default size
/ (root file system) - 50 GB (maybe some large things will be installed here...)
/swap - 32 GB - same as RAM size
/tmp - 5 GB
/var - 10 GB
/home - remaining space

Also:
Language - English
Region - Japan
Locales - en_US.UTF-8
Keyboard - American English
hostname - FEcentral
domain name - mtk.nao.ac.jp (default)
Network interface - eno1 Intel Corporation ethernet controller 10G X550T
root password - starts with a 1 instead of 0
ops user 1000 (same password as usual)
controls user 1001 (same password as usual)
package manager - deb.debian.org
HTTP proxy - blank

From the ALIGO respository, we are now using the debian bullseye 1.0.9 cdssoft instead of buster 1.0.6 as in the last entry on this topic.

For the data concentrator Debian 11 installation, I am still not so sure about the partitioning. I still haven't seen any guidelines on it. The preinstalled storage hardware is shown in figure 2, from the BIOS settings. Also, we are using the minimal Debian installer and connect to the internet during the installation. But, the Myrinet controller needs some other firmware to run (figure 3). I remember that LIGO has some link to it but can't put it on their repository. In this case we have two ethernet controllers to choose from (figure 4). But, the first one on the list also didn't work. I skipped that and went to the partitioning. It already threw out the preset partitioning with some filesystem that I don't know of (figure 5), and I'm not entirely sure how to do this one either. So I just stopped there and didn't write anything to the disk, i.e. it still boots CentOS 7

Marc Matteo

We removed FC from the AZTEC #3.

Note that the imaging unit black cover was modified so that we don't need anymore to disconnect the cables.

We checked the bulk reference sample and measured R = 0.5794 cm/W with Pin = 27.67 mW and Pt = 15.06 mW.

It is still consistent with previous estimation so we installed the AZTEC #3 on the translation stage.

We did a long z scan and estimated the 2 surfaces at z = 26.05 and 114.5 mm so that z_center = 70.275 mm

We started XY measurement at Z_center.

From the long z scan, absorption seems promising.

Marc, Matteo

Today we removed AZTEC #2 and installed the bulk reference sample.

We measured R = 0.5780 cm/W which is compatible with previous measurement within 5%.

This is reasonable so AZTEC #2 measurements are fine.

We used again first contact on the AZTEC #3 as there was some remained of the previously applied first contact and peeled.

Note for future to never use the sticky tape given by first contact.

We also applied first contact on the second surface of the 1.5 inch sapphire used for calibration.

We cutted holes in the black box covering the imaging unit in order to avoid to have to remove the cables every time we want to intall/remove KAGRA size substrates.

We started measurement of AZTEC #1 at exactly the same position as before (XY map at Z center).

Measurement is on-going but preliminary results seems compatible with previous measurements meaning that they should be fine.

Report of AZTEC #2 absorption measurements.

For reference the arrow is on top pointing towards the imaging unit.

Absorption is larger than AZTEC #1 and we can also quite clearly see the growing seed on the xy2 map (fig 2 that is measured at the z center of the substrate)

Two photos (under gluing and after gluing) are attached.