B. Bland, J. Kissel, R. Lane, K. Arai, J. Romie

While connecting the L2 (PUM) OSEMs, we ran into several problems:
(1) The temporary feedthrough connections had failed because of bent casing, so we needed to replace the pin-flipper ribbon cable, and swap the gender changer that connects directly to the in-vacuum cables.

(2) Once turned ON and connected, we immediately noticed that the L2 LR OSEM channel looked strikingly similar to a DuoTone signal (see "duotone" attachment). Through a little bit of investigation in the simulink model, we noticed that the L2 LR OSEM channel is the first ADC's (ADC0) 32nd channel (adc_0_31), in the h2susb478 I/O chassis. HOWEVER, this channel is explicitly reserve for timing tests in all aLIGO I/O Chassis, as defined by the IOP model. Dave Barker informs me that it's possible to turn this "test signal" off, but we should think of a more permanent solution for the long term, as I imagine the DuoTone test signal and the L2 LR OSEM sensor's signal will be used equally as often (i.e. almost never, and never for low-noise control). 

(3) Though L2's UL, LL, and UR appear to be showing physical signals, UR's signal's signal is much lower. However I'm reasonably confident that this is merely because the flag is fully entrenched in the OSEM, blocking all light. (see "spectra" attachment -- forgive me for the lack of calibration).