Since we want to know if the AA diagonalized signals are dominated by PR/BS motion. So we want to use a transfer function to calibrate PR/BS motion into AA diagonalized signals. There is excitation sent to PR/BS p/y when the measurement is done. The excitation is as following:

The measurement of transfer functions are attached as four figures. It is shown in them that there were some coherence between 10~20Hz. We could multiplify this spectrum with PR and BS oplev signal and compare it with the diagonalized AA signal.

After the discussion with Eleonora and Matteo, I modified the filters for AA. For old and new filters, the comparison of AA diagonalized signal is shown in the attached figure. (Blue is the old case, red is the new case)

The new filter configuration is as following:

It was reported that PR/BS local brings noise to AA. However, after the replacement of BS PSD, the AA diagonalized signal shows no difference when PR/BS local control is on or off.

The comparison of the old case (blue curve: local control increase noise around tens of Hz) and the new case (red curve: local control doesn't increase noise) is shown in the attached figrue.

To buy or make a new PSD, the gain of PSD is an important and necessary information. Therefore, I measured it as following.

The wavelength of the used laser is 635nm. I set this wavelength for the laser power meter. Then I checked the 635nm laser power used in PR chamber. It was 0.28mW.

Then I measured the PR PSD sum voltage with oscilloscope, which is 11.4V.

Therefore,the high gain PSD should have gain of 40.7 V/mW.

I forgot to measure the size of PSD, but it seems to be 1 inch. I will confirm.

As reported in elog 2258, the BS PSD showed large noise last Friday. I checked also today, the noise is still present. So we decide to replace it. As also mentioned in elog 2258, we have only a spare low-gain PSD. So we decide to use SR560 to amplify its output.

The only two SR560 could be used are the one used for CCSB lock and the one used for FC length control (feedback to END mirror). So I temporary took them and used to amplify the low-gain PSD. As shown in the first attached figure, there is a comparison of the PSD. It shows that resistors have a ratio of 100,000:500. Therefore, I set the gain of 200 for the two SR560 for PSD's pitch and yaw.

Then I compare the spectrum of this PSD with the old high-gain PSD. This is shown in the attached figure 2. It is clear that the gain of 200 is too much. I adjusted it to 50 and then, as shown in the attached figure 3, old and new spectrums match around several Hz. It is also shown in this figure that the noise floor of new PSD above 10Hz is generally smaller.

Then I checked the local control of BS also works well.

Since we have p/y coupling in AA diagonalized matrix. To remove this coupling, the pitch and yaw singal cannot be separated as before.

I modified the k1fds simulink file and now there is possibility to mix yaw to pitch or mix pitch to yaw. In this way, the pitch yaw coupling could be removed.

The new matix window is shown in the attached figure.

The oplev p/y sensing coupling was optimized long time ago. SInce recently we compare AA diagonalized signal with oplev signal. We decide to check again the oplev p/y coupling again.

The PR and INPUT have not obvious p/y coupling as shown in the attached figure 1 and 2. But there is coupling for end mirror (as shown in the attached figure 3), which was removed by putting PSD rotation angle to be zero (as shown in the attached figure 4).

Long time ago, we had issue of BS PSD pitch which shows large noise at high frequency (see elog1642). Today, we found BS PSD pitch noisy again. And this time, the spectrum is as shown in the attached figure 1, which is even worse.

To make sure it is the problem of PSD, I replaced it with another PSD, which has smaller gain. Then the spectrum is as shown in the attached figure 2. As we can see, the pitch spectrum is fine. Therefore, the old BS PSD really has some problems.

I also discussed with Eleonora, she suggested me to buy/make a new one.

The problem is solved by using directly a long ethernet cable between computer and picomotor box.

Today, when I align filter cavity, I found the output of Input pitch is very large. As shown in the first attached figure, the H3 coil has an output of 30,000. This is reaching the maximum of coil.

So I tried to offload this value with picomotor. However, there is an error coming out when I use labview to move picomotor. The error is shown in the attached figure 1. To fix this problem, I did following check:

1. We tried to move PR picomotor, which worked. Therefore, the Labview should work well. And the network connection of the old PC should be also fine.
2. We checked the ethernet cable connection to the picomotor box. But the cable is connected to a high cable (as shown in the attached figure 2). So it is not very easy to check if the cable is correct or not. But anyway, this cable is connected.
3. We also tried to plug in and out the power cable for picomotor box, which didn't solve the problem.
4. We checked also the IP address of picomotor box, which is consistent with the one used in Labview.

However, the picomotor still didn't work. I have already sent Takahashi-san an email to ask how to solve this problem.

The measurement is the same with the last comparison of AA/oplev except for that the PR/BS local control is off.

But even in this case, the AA signal is still higher than oplev signal.

This coherence check was done between PR/BS oplev singal and AA diagonalized signal. Note that there is no excitation sent to PR/BS, but the PR/BS local control loop was closed.

Note: blue curves are PR/BS local control open, red curves are PR/BS local control closed.

We could see a strong coherence between PR pitch/yaw oplev signal and AA.

Therefore, the PR local control seems to be introducing noise in pitch/yaw from 10 to several tens of Hz.

This coherence check was done between PR/BS oplev singal and AA diagonalized signal. Note that there is no excitation sent to PR/BS, the PR/BS local control loop was open.

It can be seen that there is almost no coherence above 10Hz. I think this is also reasonable, because PR/BS motion at high frequency should be similar.

As reported in elog2245, the AA noise level is in general higher than the noise of oplev from roughly 10Hz to 100Hz (looking at all Input/End pitch/yaw). This noise is suspected to come from PR/BS motion.

Therefore, the coherence check between PR/BS pitch/yaw excitation and AA signal was done. The result is shown in the attached figure 1-4. It can be seen that:

1. Compared with BS pitch excitation, all AA singals have high coherence between 10 and ~30Hz. (Fig 1)

2. Compared with BS yaw excitation, Input yaw shows the most coherence between several Hz to ~30Hz. (Fig 2)

3. Compared with PR pitch excitation, all AA signals have high coherence between ~30Hz to 100Hz. (Fig 3)

4. Compared with PR yaw excitation, Input yaw shows the most coherence between several Hz to ~30Hz. (Fig 4)

Besides, the AA signal with PR/BS local control loop open was also checked. The result is shown in the attached figure 5. It is clear that, the noise floor from ~10Hz to 100Hz becomes generaly lower. But there is no difference in End mirror yaw.

Later on, I found that all the filters disappear in foton.

Eleonora checked that we have archive file in the directory '/opt/rtcds/kamioka/k1/chans/filter_archive/k1fds'. The file used in foton is '/opt/rtcds/kamioka/k1/chans/K1FDS.txt'.

Then Shoda-san helped to check them. 'ls /opt/rtcds/kamioka/k1/chans/filter_archive/k1fds -all' was used to check the date of these files. The latest archived file in that directory was found to be 'K1FDS_201021_164656.txt' However, it was also shown in the terminal that this latest file has size of 3075 (usual size is 107155). We opened the file and found that the latest archived file is actually empty. In the end, we found  'K1FDS_201017_210326.txt' should be the latest useable file.

By using 'cp /opt/rtcds/kamioka/k1/chans/filter_archive/k1fds/K1FDS_201017_210326.txt /opt/rtcds/kamioka/k1/chans/K1FDS.txt', the filters are copied to foton. Now filters also work well!

When the transfer function is measured in diaggui, several choice could be used for measurement. Especially, when performing FFT measurement, there is 'Gaussian' and 'uniform' noise to be chosen. I checked today what is the difference of them.

I used Diaggui to generate these two noise as shown in the first figure. Then the spectrum of them was measured and shown in attached figure 2.

The conclusion is that both of them are white noise. But the 'Gaussian' noise is about twice the amplitude of 'uniform'.

It was figured out that there were two problems happened at the same time and caused this problem.

1. Instead of using 'make install-k1fds', I was using 'make install -k1fds'. By using correct command, the problem was solved.

2. One of the directory was full (/opt/rtcds/kamioka/k1/target/fb/log/old was as large as 18GB) . Then I couldn't make k1fds. By using 'sudo rm -r old', this problem was solved.

Tips:

To check if k1fds is running, command 'lsmod' could be used. After using it, if you see the name k1fds is listed on the left side in a certain column, it means k1fds is running.

To check the space used by different directory, 'du -h --max-depth=2 .' should be used.

Shoda and Yuhang

I found that the driving matrix of AA had large coupling last Friday. So I was thinking to make the driving matrix not seperate in pitch and yaw. It means to make the 2*2 matrix be a 2*4 matrix. For example, to control the yaw motion, there is not only signal coming from yaw but also from pitch.

Then I asked Shoda-san to modify the k1fds code. She helped me make the modification described as above.

But then, later on last Friday. By improving the driving matrix index with the separation of pitch and yaw, the pitch/yaw coupling becomes much better. So I decided by myself to modify it back.

However, after I modified it back. I found I couldn't make k1fds. The problem showed up as

gzip: stdout: Np space left on device.

make: ***[k1fds] Error 1

However, although this issue reased up, I was able to use control loops. So I didn't care about that.

Then, the day after, I found filters in foton disapeared. 

Eleonora and Yuhang

Firstly, we found that all the filters disappeared in foton (as shown in the attached figure 1).

Then we tried to restart standalone computer. However, after that, k1fds stopped working (as shown in the attached figure 2).

At the same time, we found that by using command 'df', /dev/sda1 shows 100% used (as shown in the attahed figure 3).

Eleonora tried to ssh standalone, and used command 'lsmod', and found there was no k1fds. She tried command 'startk1fds'. But it didn't work (see attached figure 4).

So probably the problem is connected with the full of /dev/sda1.

To check how AA affect input/end mirrors, I checked their oplev signals when AA loop is on/off.

From the measurement, the yaw motion of input/end mirrors is actually increased by AA loop.