While at the MC2 table, we noticed that it has some optical problems:
We estimated that the power in the IMC is (1 W)*Finesse/pi = 500 W. The MC2 Transmission spec is < 10 ppm, so the power on the table is probably ~5 mW. Since the PDA255 has a transimpedance of 10 kOhm and a max output power of 10V, it can handle up to ~1 mW. Probably we can get the QPD to handle 4 mW.
Gautam, Steve 3-27
We measured MC2 transmitted power right at the uncoated window ~2.5 mW The beam was just a little bigger than the meter.