Our previous plan turned out to be ineffective due to the mirror not transmitting all of the P polarization, but only a fraction. We now used the PBS within the faraday isolator (FI) as a pickoff, and rotate the HW plate at the input to control the power reflected. When the HW plate is maximized for transmission through the FI, I measured 13.4 mW into the FI, 12.00 mW at the output and 1.18 mW picked off. I then used a mirror to steer the picked-off beam onto the 1811 new focus photodetector. Using the DC coupled output I maximized the output on an o-scope, which was at the level of 400 mV. The AC output was then connected to the HP4395A analyzer from which the data was taken.
Edit: I have now put a focusing mirror with a focal length of 5cm before the PD, the o-scope now reads 3.41 V. A pdf of the layout with these updates can be found at https://nodus.ligo.caltech.edu:30889/ATFWiki/lib/exe/fetch.php?media=main:experiments:psl:ctn_optical_layout.pdf