After the BS istallation, I proceed with the implementation of the local controls as it was done for the PR mirror in July.

OPTICAL LEVER

As a first thing, I restored the opltical lever (see first attaced picture). In order to have the  PSD voltage sum <15, to avoid saturation, I put a filter in the laser path to  reduced the power.

The power reaching the PSD is about 340 mW which corresponds to a voltage sum of 14.8 V.

TRANSFER FUNCTIONS AND CONTROL LOOPS

1) I have measured the mechanical transfer function of the mirror when exciting yaw and pich respectively (plot pag 1 and 2 of the attached document).

2) I have measured the open loop transfer function of the two degree of freedom (plot pag 3).

3) I have closed the two loops and plotted the comparison between the calibrated spectrum when the loops are open and when they are close (plot pag 4 and 5).

CALIBRATION

In order to calibrate the signal I assuemed that the PSD had the same calibration factor measured for the PSD of the same type used for the PR (see entry 276) (maybe this has to be verified..)

I follewed the same procedure explained in entry 276.

n_cal = 0.0071+/- 0.0002  (normalzed calibration)

arm = 0.60 m +/- 0.05 m  

V_sum = 14.8 V

Cal_tot =  n_cal/(2*arm*V_sum) =  (3.04 +/- 0.26 ) e-4 [1/V]  

Last friday I observed that the coil driver (#4) used to control the input mirror was not working properly. It also made the crete produce an alarm sound when connected. We have replaced it with another coild driver (#1). In order to do it, we had to restore the connector number 4 that was missing in that coil driver.

We dispose of 6 coil drivers, originally used in TAMA, which are numbered from 1 to 6. (#2 is actually not numbered)

Here a recap on the coil drivers used for filter cavity and input telescoope mirrors.  (See also attached pictures)

Coil driver #1:  used for the INPUT MIRROR  (connector 4 was missing and had to be replaced)

Coil driver #2:  used for the BS TELESCOPE (it is actually not numbered)

Coil driver #3:  not used  (probably is not working properly, to be checked)

Coil driver #4:  not used (previously used for the INPUT MIRROR but it deesn't work anymore)

Coil driver #5:  used for PR TELESCOPE

Coil driver #6:  used for the END MIRROR

Workers: Tatsumi, Takahashi, Yuefan, Eleonora

This morning the BS mirror has been successfully suspended and the suspension has been installed in the BS chamber.

Coils have been connected as shown in the first attached picture. 

Today I checked the I/O channals that will be needed for the control of the BS suspension (part of the filter cavity injection systems). Here a brief recap of the CPUs and the I/0 ports used for all the controlled suspensions. See also first picture in the attached file.

INPUT MIRROR  (4 input , 4 output)

CPU:   SAS_NM1b (133.40.121.74)  in central room

INPUT : SC1 MOD 6 /ai 4:7

OUTPUT: DEV1 /ao 0:3

TELESCOPE MIRRORS  BS ans PR (4 input, 8 output)

CPU: SAS-NM2b (133.40.121.78) in central room

INPUT: SC1 MOD 3 /ai 0:7   (1, 2 used for PR   5,6 used for BS)  NB: #4 doesn't work!

OUTPUT DEV2 /ao 0:7  (1, 2, 3, 4 used for PR  5, 6, 7, 8 used for BS)

END MIRROR (4 input, 4 output)

CPU: SAS-EM2a (133.40.121.75) in end room

INPUT: SC1 MOD3 /ai0:3

OUTPUT: PXI1 Slot3/ao 0:3

NB: Some days ago I had to change the port in the swtch that was connecting the CPUs in the central room to the network. I found out that the port used previusly (see attached picture 2)  didn't work anymore and that was the reason why I wasn't able to connect the supervisor PC to the remotes targets.

Workers: Tatsumi, Takahashi, Yuefan, Eleonora

During the installation work, one standoff was dropped off from the mirror.

[Glueing work]

Tatsumi made glueing work for standoff at TAMA.

[Next]

We will make installation work on Thursday afternoon.

[GOOD NEWS]   I successfuly hang BS dummy mass with four tungsten wires of 100 micron.

[BAD NEWS]    Dumping mass of the intermediate mass is missing.

Together with this mass, strong magnets and two hanging rods are needed.

[21 Nov.] I found these at bottom of rack for absorption measurement system.

Another missing parts are base plates to sit 10 cm diameter masses for hanging JIG.

I recommend to keep whole parts in one container box.

Worker: Yuefan Guo, Daisuke TATSUMI

We failed to set suspension wire of BS mirror.

We try three times and always break the suspesion wire during the pulling up

the aluminum dummy mirror.

I guess that these failure come from systematic reasons.

Therefore, we stop the work today.

-----------------------------------------------------------------------------------------------------------

I know the safy factor of tensile strength is about 2 for 10cm fused silica mirror.

Because BS mirror has different dimensions, I calculate several parameters.

[[  ]]

It means that for 15cm alumimum dummy mirror,

there is almost no safety factor. If tension balance of four wires is not good,

the wires will break easily.

I decide to change the wire diameter to 100 micron.

P.S.

High wire tensions are needed to reduce its mechanical loss.

For stearing mirror of the filter cavity, we do not take car of thermal noises.

Members: Sakai, Manuel

We improved the VI that makes the absorption maps. Now it can also make Circular maps. We added an elapsed/remaining time and progress indicator. We also cleaned up the Front Panel to make it simpler. Next, we will include the filters.

I finished the glueing work for TAMA BS mirror.

I measured the beam height at TAMA center room.

The beam height is about 1200 mm.

This is consistent with Takahashi-san's answer.

I checked some EOM at TAMA.

I found that Yuefan already installed a custom EOM for SHG.

I know the following things.

1) Custom EOM crystal (producted by DELTRONICS Inc.) was assembed into Newport 4003 housing. And then its resonant frequency was tuned to be 15.235 MHz by New Port Inc.

2) To reduce a power density of the passing beam, the crystal has dimensions of 4 x 4 x 40 mm. In addition, holes on the housing were expanded to 4 mm in diameter. Normal New Port EOM 4003 has 2 mm of its aperture.

3) At TAMA site, we have several EOMs as listed bellow.

I upload a PDF on TAMA RF photodetector.

I upload three PDF files on a system of TAMA Faraday Isolator. I do not have information on Faraday crystal.

Members: Sakai-kun, Manuel,

We made a VI that takes a single input, uploads the array buffer, applies a median and an average filter and returns a filtered output. There are controls for the filter array sizes and switches to enable and disable the filters. We put this VI in the loop of the VI that shows the signals, we filtered the X and Y signals and plot the AC and Phase. The plots show the filtered signals in white and the unfiltered in gray.

I contacted to the company (Japan Laser Coorp. as a japanease agency of Newport). The currect legs can be separated into upper and lower parts. Cheapest way to change the height is to change the lower part of the legs. To get a quotation, about one week is needed. An expected delivering time is about three months.

Minutes of Meeting
November 2nd, 2016
Participants: M. Barsuglia, E. Capocasa, R. Flaminio, Y. Guo, M. Tacca

1. Coating at LMA
Discussion on going.

2. Optical scheme
New optical scheme produced by Matteo and Eleonora.

2a. Which polarization shall we use? The OPO and the SHG seems to work with S-pol (TBC with
Matteo Leonardi). Which polarization one is compatible with the EOM that we have?
Yuefan wil check.

2b. SHG lock. It can be done in transmission. GEO did it in transmission. Virgo is doing
it in reflection. If so we can remove the optics to do the lock-in in reflection.

2c. Share of IR power between SHG path and 1064IMC path? Need to check with Matteo Lombardi
what is the minimum power required for the SHG.

2d. Modulation frequency for the SHG/1064MC: GEO was using 75MHz. Virgo is using 80 MHz.
We are planning to use 15 MHz.

2e. IMC's. Mechanical design received form JP Zendri. Finesse: 500? Polarization: S?
Raffaele will consult with Matteo Lombardi. APC team will consult with people at LKB.

2f. Telescopes. Now that the optical lenght are fixed, telescopes can be studied.
Yuefan is studying the telescope for the SHG. Matteo Tacca will pass to Yuefan
the information about three lenses telescopes.

3. Window on vacuum chamber
Flange size is about 15 cm
KAGRA design received from Akutsu. With KAGRA design max window size will be ~9cm.
Matteo Tacca will ask Virgo design for same type of flange.

4. Optical table height. Tatsumi is investigating possible solutions to ahve the beam height
at the same height as the window on the vacuum chamber.

5. Visit to NAOJ of Matteo Tacca. Goal of visit will be the set-up of the green path
for the filter cavity control and the injection into the OPO. Need to define the list of
components to be bought.