On Mar. 9. YamaT, Akutsu

Abstract

We succeeded to open the shutter in the PSL room, and input the laser light to IMC; still there are homeworks to be resolved... Now I tuned the laser power 30mW and P-pol (maybe).

Detail

After the inspection of the shutter driver (16208), we took it back to the PSL room. We found that the control signal to open the shutter, 5V, could not be provided from the Dsub-to-BNC circuit board (S1605873) installed at the rack in the PSL room. It seems this Dsub-to-BNC circuit is connected to also the other signals such as PMC heater and PZTs for steering mirrors (IP?) in the PSL room (, plus towrad Mach-Zender-ish one, but this is unused), so this issue should affect wider area... need to be resolved as early as possible.

Anyway, with a power supply that was tentatively lend from the electronics shop in the Mozumi building, we are able to provide 5V to the shutter driver circuit (Fig. 1, and the shutter opened! When the 5VDC was turned on, the display shows 30mA/5VDC.

Using the motorized HWP, I tuned the power to be sent to IMC to 30mW (Fig. 2); when the shutter is closed, the shutter mirror reflects the light beam to the Ophir power meter, and the 30mW is the read of this power meter. So if the shutter opens, this read is lost. This is not so useful for commissioning... how do we improve this?

Finally I put a (non-motorized)HWP to make the output beam to IMC be P-pol, but I forgot to check the polarity.. need to be done later.

• Fig 3: shutter opened, and a non-motorized HWP is inserted in the optical path.
• Fig 4: shutter closed.

As you can see, it is not so easy to just take out the "shutter", which is more complicated mechanism than the one just imaginable with the word's sound.