Blue line is when ISS is on and Green line is when ISS is off.
By turning on ISS, the intensity noise is suppressed and DARM sensitivity doesn't change.
The reason for this is that the coupling from the intensity noise to the interferometer is small at the current laser power.
--memo--
IMC output power : 1.4W
Out-of-loop PD output : 0.55V (1.75mW)
One is the same as the one I posted yesterday (Green).
The other November 29 data (Black).
Due to the reduced input power of the PD, the intensity noise has been reduced, and the relative intensity noise has also been reduced.
[2019/11/29] Out-of-loop PD input : 1.4 V (4.4 mW)
[2020/02/03] Out-of-loop PD input : 0.55 V (1.8 mW)
I calculated the "relative" intensity noise from the intensity noise.
The plot is shown below.
It can be seen that RIN depend on the power.
As the power increases, the RIN increases below 2 kHz.
[29/11/2019] Out-of-loop PD output : 1.4 V (4.4 mW), IMC output : 3.6 W
[03/02/2020] Out-of-loop PD output : 0.55 V (1.8 mW), IMC output : 1.4 W
