Here is a diagram for our intensity noise coupling measurement.
The below is a plot for the intensity noise on the DCPD. (I forgot to take a spectra of the PD dark noise)
For some reason, the RIN spectrum becomes sometimes noisier and sometimes quieter. Note that after 10 pm it's been in the quiet state for most of the time.
An interesting thing is that the structure below 3 Hz looks like excited by motion of the MC when it's in the louder state.
A photo diode and an AOM driver have been newly setup on the PSL table to measure the intensity noise coupling to the beat note signal.
We tried taking a transfer function from the PD to the beat, but the SNR wasn't sufficient on the PD. So we didn't get reasonable data.