KAGRA Logbook

MIF (General)

kazuya.yokogawa - 23:47 Tuesday 11 September 2018 (6082)

Green beam alignment

[Michimura, Enomoto, Takeda, Sugimoto, Yokogawa]

Beam shutter for green laser

We installed beam shutter for green laser. The beam shutter for GRX(Green X) is put on the POP table. However, We could not drive the beam shutter in trigger(remote) mode. (We can drive in manual mode.) We don't know why the beam shutter didn't drive in trigger mode.

As for GRY; we could not install because the POS table has not been installed yet. We only prepared the cable for GRY beam shutter and put on the top of LSC rack. (Attached picture is the cable for GRY beam shutter.)

Alignment of green beam

First we aligned the green beam to hit the center of PR3 using steering mirror in PR2 chember. Then we confirmed the green beam hits the center of ITMX and path through the center of NAB in the IXA chember.

Images attached to this report

Comments to this report:

yuta.michimura - 21:08 Sunday 23 September 2018 (6266)

[Enomoto, Michimura]
The beam shutter (Thorlabs SH1/M; The driver is KSC101) for X green beam worked with trigger mode if the trigger signal was generated using a signal generator.
So the problem is something related to DAC.
We found that the Dsub-BNC Converter (DAC) Chassis (Ser. Num JGW-S1605872) gives an oscillated signal at ~1 MHz with an amplitude of volts, when probed with a cable which has a length of "f1 130 deg" (6.4m I suppose).
To investigate the chassis, we brought it back to the Mozumi office, and found nothing strange so far. Hmm...

Tips on using beam shutter SH1/M with KSC101
- You don't need to connect with PC
- You don't need a special setting. The default is OK.
- You just have to change the mode to "trigger mode" using KSC101. And turn the wheel up once.

kazuya.yokogawa - 0:19 Tuesday 25 September 2018 (6274)

[Michimura, Enomoto, Sugimoto, Yokogawa]

Yesterday, Michimura-san and Enomoto-san found that the DAC chassis (Ser. Num JGW-S1605872 ) gives an oscillated signal at ~1MHz. So, we changed to the new DAC chassis (Ser. Num JGW-S1605870) and used Low Path Filter in order to avoid the oscillation at 1MHz.

However, it was not the real reason why the beam shutter does not work in trigger mode. The point of the real reason was at ground. We found that outside the BNCs of the DAC chassis are not grouded in default. So, we connected the outside of BNC to the ground of DC power supply. (See the attached picture.) By doing so, the beam shutter worked with trigger mode!!

But this is not cool. We will drop the outside of BNC to ground using jumper pin.

Summary

Probably the DAC chassis (S1605872) we used before was not broken.
The beam shutter for green laser is working without problem with trigger mode.
We will drop the outside the BNC of the previous DAC chassis (S1605872) using jumper pin and exchange with S1605870.

Images attached to this comment