Matteo, Yuhang, Eleonora

We measured the QPD2 electronic noise with spectrum analyzer using 32 dB amplification. 

Pic1: Amplified QPD2 noise compared with 32 dB amplifier noise and spectrum analyzer.

Pic2: Same plot of entry #2121 where we added QPD electronic noise. Note that the data were divided by a factor 40 to subtract the 32 dB amplication used for the measurement. We didn't plot data below 1Hz as we assumed they are dominated by the spectrum analyzer noise.

We verified that the QPD measurement doesn't change when we added a bandpass filter (https://www.minicircuits.com/WebStore/dashboard.html?model=SIF-70%2B) before the 32 dB amplifier.