Update on "The Effect" (The Voltage Noise at the Green PD Difference in my circuit changes depending on whether or not I have light on my IR PDs)

I checked the circuit a little more in detail, and I see the behavior at the output of the transimpedance amplifier for both PDs.

• I am using LT1792
• I short + to ground
• I put a 50 Ohm between - and ground
• The feedback is a 100k resistor, and a 100 pF capacitor
• Again, the behavior is a big noise increase when the IR circuitry is going.
• I unplugged the control signals from their respective destinations (PZT Drive box and AOM driver), but the behavior persists.
• With the box off, and the MZ Locked, this noise is (slightly above) about the same as the "MZ Phase Noise" above 10 Hz
• Below 10Hz the phase noise (or not this noise) is higher
• If I disconnect the IR PDs from my box the effect is gone (I'm using the same power supply for the ISS box and my box - I was worried that I was tugging the ground around somehow)
• I pulled EVERY op amp from the IR paths (including the feedback) - just 6 left. The effect persists.
  • The above op amps are the transimpedance amplifiers for each PD, the balancing op amps, and the sum and difference op amps.
• If I connect either one of the IR PDs (with a terminator on the other input) into either of the inputs, the effect is there