[Michimura, Enomoto]

We checked the operation of the DC QPDs on OMC breadboard, and they seem to work properly.

= How we checked =
First we checked the diode drop at the outside of the feedthrough, and it was fine.
Then we illuminated the QPDs by a handy flash light, connected the feedthrough pins to an oscilloscope, and saw the signals.
The settings of the input impedance were 1 MOhm.

For QPD1, we were able to identify which quadrant corresponds to which pins of the feedthrough.
The results were:
TOP
A4 A3
A1 A2
BOTTOM
(looking at the QPD surface).

For QPD2, we could not identify which one corrsoponds to which, since it was almost impossible to have an access to the QPD; we could not cover the QPD surface.
We just confirmed that all the quadrants gave us currents when there were lights on them.

= A temporary QPD driver =
I hope this topic be reported by Michimura-san