KAGRA Logbook

I put a wind shield to the QPD side, and replaced the light source.

Summary: [WAS] #203246 -> [IS] #228144
I firstly replaced the old one with #228143, but the sum count of the QPD was only doubled (ex. 3000 cnts -> 6500 cnts for the tilt QPD). It was disappointing; actually lower than my expectaion; according to the Yamamoto-san's sum monitor, the sum count of the old tilt QPD was around 8000 at the first time.
Then, I just replaced it with #228144 but the count read was not varied so much.
For some reason, I unpluged the AC power supply of the light source at the wall outlet in the clean booth, and took time to look for the other AC outlet, but I could not find useful ones nearby. So I brought the AC line back the original outlet. (Note that every time I detached the light sources here, I just unpluged the DC connector on the main body of the light souce.)
Then (perhaps occasionally) the count seemed to start recovering gradually... and now it reaches 7800; I am not sure well whether this would happen reproductively...
It might be the timing to use DC power supply for QPDs.

It was so tricky... please be careful if you would like to do re-centering of the QPDs and the PSD inside of it.
So far today, I did not move any optical components on the breadboard at the QPD side.
I put four metal pillars on the breadboard in order to support aluminum foils. The first idea of mine was to put a plastic plate on the pillars as well, but to do so, I needed to do drilling holes to the plastic plate. I tried to avoid the work, and just went ahead to putting aluminum foils somehow without the plastic plate.
By the way, the light-source side had been already done (10537).