Participants : Eleonora, Emil, Yuhang

We performed 3 new losses measurements using the "lock-unlock" techique.

The IR reflected power can be seen in fig "23to26.pdf".

To extract the losses value for the measurement made on April 23d 2018  I only extracted the firsts values to avoid the noisy part of the signal.

The April 26th measurement was really noisy. However, 3.69% of the power were coupled to the FC 1st order mode and 2.49% with the 2nd order.

In order to better investigate the source of this noise, we will add a beam splitter and a photodiode on the IR injection path in order to see if there is any coupling between the laser power fluctuations and  the IR reflected power or if we should investigate other sources.

It also seems that the IR reflected power fluctations are higher when the frequency of the AOM is such that the IR 0 order mode is resonant in the FC.

However, if we change slightly this frequency, the fluctuations seems to disappear.

We will install a camera on the IM viewport where a 2" mirror was installed to see if we can extract some informations about the scattered light.

The computation of the 3 measurements can be seen on "23to26meas.png".

The noisy measurement leads to the huge error bar.