Kakeru and Kiwamu
We placed a QPD on the PSL bench for PSL angle monitor.
I checked a broken QPD, which was placed for PSL angle monitor, and finally I cocluded one segment of the quadrant diode was broken.
The broken segment has a offset voltage of -0.7V after 1st I-V amplifier. It means the diode segment has a current offset without any injection of light.
Tomorrow I will check a new QPD for replacement.
As we mentioned before, old QPD which used to be placed is broken.
And we put broken QPD into the "photodiodes" box under the soldering table.